Co-reporter:Shuzhen Lv, Yi Li, Kangyao Zhang, Zhenzhen Lin, and Dianping Tang
ACS Applied Materials & Interfaces November 8, 2017 Volume 9(Issue 44) pp:38336-38336
Publication Date(Web):October 13, 2017
DOI:10.1021/acsami.7b13272
A class of 0-dimensional/2-dimensional (0D/2D) nanoheterostructures based on carbon quantum dots (CQDs) and graphitic carbon nitride (g-C3N4) was designed as the signal-generation tags for the sensitive photoelectrochemical (PEC) immunoassay of prostate-specific antigen (PSA) coupling with the copper nanoclusters (CuNCs). Combination of CQDs with g-C3N4 promoted the photoexcited electron/hole separation and largely increased the photocurrents of the nanoheterostructures. Initially, a sandwich-type immunoreaction was carried out on monoclonal anti-PSA antibody-coated microplate by using PSA aptamer linked with CuNCs as the tracer. Accompanying the immunocomplex, the carried CuNCs were dissolved under acidic conditions. The as-released copper ions from the CuNCs could be captured onto the CQDs/g-C3N4 nanoheterostructures via the amino-group on the CQD surface as well as the −NHx (x = 1, 2, 3) of g-C3N4 nanosheets. The strong coordination of the Lewis basic sites on the CQDs/g-C3N4 with Cu2+ decreased the photocurrent of the nanoheterostructures. Under optimal conditions, CQDs/g-C3N4 nanoheterostructures displayed good photocurrent responses for the detection of PSA within the dynamic linear range of 0.02–100 ng mL–1 and a limit of detection (LOD) of 5.0 pg mL–1. This method was also evaluated for quantitative screening of human PSA serum specimens by using the referenced electrochemiluminescent enzyme-linked immunoassay (ECL-ELIA) and gave good matched results between two methods. Additionally, this system was beneficial to explore the charge-separation and photoinduced electron transfer mechanism in the photoelectrochemical sensing protocols.Keywords: carbon quantum dots; copper nanoclusters; graphitic carbon nitride; nanoheterostructures; photoelectrochemical immunoassay;
Co-reporter:Youxiu Lin, Qian Zhou, and Dianping Tang
Analytical Chemistry November 7, 2017 Volume 89(Issue 21) pp:11803-11803
Publication Date(Web):October 6, 2017
DOI:10.1021/acs.analchem.7b03451
A novel signal-amplified strategy based on dopamine-loaded liposome (DLL) was developed for competitive-type nonenzymatic photoelectrochemical (PEC) immunoassay of small- molecular aflatoxin B1 (AFB1) in foodstuff, using Mn2+-doped Zn3(OH)2V2O7·2H2O nanobelts. The signal was amplified by high-loaded capacity of liposome and the highly efficient dopamine molecule to enhance photocurrent of Mn2+-doped Zn3(OH)2V2O7·2H2O nanobelts. The loaded dopamine in the liposome was used as an electron donor to scavenge the hole and inhibit the charge recombination. To design such an immunoassay system, a AFB1–bovine serum albumin (AFB1–BSA) conjugate was covalently bound with the multifunctional liposome via the cross-linkage glutaraldehyde, whereas monoclonal anti-AFB1 antibody was labeled onto a magnetic bead by typical carbodiimide coupling. Upon addition of target AFB1, a competitive immunoreaction was carried out between the analyte and the AFB1–BSA–DLL for the conjugated antibody on the magnetic bead. Followed by magnetic separation, the carried DLL on the magnetic bead was lysed by using Triton X-100 to release the encapsulated dopamine. The as-produced dopamine (as an elector donor) increased the photocurrent of the Mn2+-doped Zn3(OH)2V2O7·2H2O nanobelts. The photocurrent depended on the as-released amount of the dopamine. The change in the photocurrent enhanced with the increasing AFB1 concentration. Under the optimal conditions, Mn2+-doped Zn3(OH)2V2O7·2H2O nanobelts exhibited good photoelectrochemical responses for the detection of AFB1 and allowed the detection of AFB1 at a concentration as low as 0.3 pg mL–1 within a linear range from 0.5 pg mL–1 to 10 ng mL–1. Importantly, this system provided an ideal PEC immune sensing platform based on Mn2+-doped Zn3(OH)2V2O7·2H2O nanobelts and the high-loaded liposome for the detection of small molecules.
Co-reporter:Zhenzhong Yu;Shuzhen Lv;Rongrong Ren;Guoneng Cai
Microchimica Acta 2017 Volume 184( Issue 3) pp:799-806
Publication Date(Web):2017 March
DOI:10.1007/s00604-016-2071-5
The authors describe a highly efficient photoelectrochemical (PEC) scheme for the determination of hydrogen peroxide (H2O2). BiVO4 microrods were hydrothermally synthesized and deposited on fluorine - doped tin oxide (FTO) glass which acts as the working electrode. Scanning electron microscopy, X-ray powder diffraction and Raman spectroscopy were utilized for the characterization of the microrods. On irradiation with visible light, the holes generated in the microrods are capturing electrons from H2O2 to produce a photocurrent at an operating potential of 0 V vs. Ag/AgCl. Under optimal conditions, the photocurrent increases with the concentration of H2O2 in the range from 50 μmol·L−1 to 1.5 mmol·L−1, and the limit of detection is 8.5 μmol·L−1 (at 3σ). A repeatability and intermediate precision of ≤6.6% was accomplished at H2O2 levels of 0.1, 0.5 and 1.0 mmol·L−1. The method was applied to the determination of H2O2 in spiked sterilized milk samples and gave satisfactory results. As the method works at zero potential, the photocurrent can be measured with simple instrumentation such as digital multimeters, and this will enable expensive electrochemical workstations to be replaced in future.
Co-reporter:Zhenli Qiu, Jian Shu, Yu He, Zhenzhen Lin, Kangyao Zhang, Shuzhen Lv, Dianping Tang
Biosensors and Bioelectronics 2017 Volume 87() pp:18-24
Publication Date(Web):15 January 2017
DOI:10.1016/j.bios.2016.08.003
•We designed a fluorescent aptasensor for sensitive detection of lysozyme.•CdTe/CdSe quantum dots were used as the donors.•The assembly of quantum dots and hemin/G-quadruplex was used for signal amplification.•Rolling circle amplification and strand hybridization was utilized.Lysozyme with a small monomeric globular enzymatic protein is part of the innate immune system, and its deficiency can cause the increased incidence of disease. Herein, we devise a new signal-enhanced fluorescence aptasensing platform for quantitative screening of lysozyme by coupling with rolling circle amplification (RCA) and strand hybridization reaction, accompanying the assembly of CdTe/CdSe quantum dots (QDs) and hemin/G-quadruplex DNzyme. Initially, target–triggered release of the primer was carried out from DNA duplex via the reaction of the aptamer with the analyte, and the released primer could be then utilized as the template to produce numerous repeated oligonucleotide sequences by the RCA reaction. Following that, the formed long-stranded DNA simultaneously hybridized with the CdTe/CdSe QD-labeled probe and hemin/G-quadruplex DNzyme strand in the system, thereby resulting in the quenching of QD fluorescent signal through the proximity hemin/G-quadruplex DNzyme on the basis of transferring photoexcited conduction band electrons of quantum dots to Fe(III)/Fe(II)-protoporphyrin IX (hemin) complex. Under optimal conditions, the fluorescent signal decreased with the increasing target lysozyme within the dynamic range from 5.0 to 500 nM with a detection limit (LOD) of 2.6 nM at the 3sblank criterion. Intra-assay and interassay coefficients of variation (CVs) were below 8.5% and 11.5%, respectively. Finally, the system was applied to analyze spiked human serum samples, and the recoveries in all cases were 85–111.9%.
Co-reporter:Ying Tang;Wenqiang Lai;Jin Zhang
Microchimica Acta 2017 Volume 184( Issue 7) pp:2387-2394
Publication Date(Web):27 April 2017
DOI:10.1007/s00604-017-2268-2
This work reports on a sensitive colorimetric immunoassay for aflatoxin B1 (AFB1) in foodstuff. The reagent L-ascorbic acid 2-phosphate (AAP) is added to the system, and alkaline phosphatase (ALP) hydrolyzes AAP under formation of ascorbic acid and phosphate. The ascorbic acid produced reduces chloroauric acid to form zero-valent gold (in the form of nanoparticles). Hence, Au(III) is no longer available to oxidize 2,2′-azinobis(3-ethylbenzthiazoline-6-sulfonate) (ABTS) to form a green product. Rather, the solution remains colorless. By using ALP-labelled monoclonal anti-AFB1 antibody, a competitive enzyme-label immunoassay was developed for AFB1 in a microplate coated with the AFB1-BSA conjugate. Under optimal conditions, the absorbance of the solution at 415 nm increases linearly with increasing AFB1 concentration in range from 10 pg·mL−1 to 100 ng·mL−1 (while the color gradually turns to green), and the detection limit is 7.8 pg·mL−1. The precision of the method (expressed as RSD) is ±9.7%. The accuracy was validated by analyzing both naturally contaminated and spiked food samples, and the results matched the results obtained by ELISA very well.
Co-reporter:Kangyao Zhang, Shuzhen Lv, Zhenzhen Lin, Dianping Tang
Biosensors and Bioelectronics 2017 Volume 95(Volume 95) pp:
Publication Date(Web):15 September 2017
DOI:10.1016/j.bios.2017.04.005
•CdS:Mn QDs-functionalized g-C3N4 nanohybrids was designed for detecting biomarker.•Hemin/G-quadruplex-based DNAzyme was introduced in this system.•Signal amplification was achieved by DNAzyme concatamers and enzymatic biocatalytic precipitation.A new photoelectrochemical (PEC) immunosensor based on Mn-doped CdS quantum dots (CdS:Mn QDs) on g-C3N4 nanosheets was developed for the sensitive detection of prostate specific antibody (PSA) in biological fluids. The signal derived from the as-synthesized Cd:Mn QDs-functionalized g-C3N4 nanohybrids via a hydrothermal method and was amplified through DNAzyme concatamers on gold nanoparticles accompanying enzymatic biocatalytic precipitation. Experimental results by UV–vis absorption spectra and photoluminescence revealed that CdS:Mn QDs/g-C3N4 nanohybrids exhibited higher photocurrent than those of CdS:Mn QDs and g-C3N4 alone. Upon addition of target PSA, a sandwich-type immunoreaction was carried out between capture antibodies and the labeled detection antibodies. Accompanying introduction of gold nanoparticles, the labeled initiator strands on the AuNPs triggered hybridization chain reaction and the formation of DNAzyme concatamers in the presence of hemin. The formed DNAzyme catalyzed 4-chloro-1-naphthol (4-CN) to produce an insoluble/insulating precipitate on the Mn:CdS QDs/g-C3N4, and blocked the light harvesting of Mn:CdS QDs/g-C3N4, thus resulting in the decreasing photocurrent. Under optimal conditions, the immunosensor exhibited good photocurrent responses for determination of target PSA, and allowed detection of PSA at a concentration as low as 3.8 pg mL−1. The specificity, reproducibility and precision of this system were acceptable. Significantly, this methodology was further evaluated for analyzing human serum samples, giving well-matched results with referenced PSA enzyme-linked immunosorbent assay (ELISA) method.
Co-reporter:Shuzhen Lv, Kangyao Zhang, Zhenzhen Lin, Dianping Tang
Biosensors and Bioelectronics 2017 Volume 96(Volume 96) pp:
Publication Date(Web):15 October 2017
DOI:10.1016/j.bios.2017.05.027
•A new photoelectrochemical immunosensor was designed for detecting biomarker.•Hemin/G-quadruplex-based DNAzyme was used for signal amplification.•Hemin was acted as a hole-trapping reagent for p-CuBi2O4 nanocrystals.•Nanogold/p-CuBi2O4 was utilized to enhance the efficiency of charge separation.A novel p-type semiconductor material (p-CuBi2O4) is designed for the construction of split-type photoelectrochemical (PEC) immunosensor for alpha-fetoprotein (AFP) with the hemin assistant to enhance the cathodic photocurrent. Initially, the photocathode of PEC immunosensor is fabricated by p-CuBi2O4 on a layer of gold nanoparticles (AuNPs, as a front contact of p-CuBi2O4) to enhance the efficiency of charge separation. In the presence of target AFP, a sandwich-type immunoreaction was carried out in capture antibody-coated microplate by using detection antibody and hemin-based G-quadruplex (labeled on the AuNP) as the signal probe. Upon exonuclease I (Exo I) introduction, the enzyme digested the hemin/G-quadruplex-based DNAzyme to release the hemin[Fe(III)], which captured the generated electrons of p-CuBi2O4-based photocathode to enhance photocurrent via the reduction of hemin[Fe(III)] to hemin[Fe(II)] in PEC detection system. Under the optimal conditions, the split-type photocathodic immunosensor showed a wide linear dynamic range from 50 pg mL−1 to 20 ng mL−1 at a limit of detection (LOD) of 14.7 pg mL−1 toward target AFP. Moreover, the PEC immunosensor also displayed high specificity and good reproducibility. Favorably, method accuracy was evaluated to analyze human serum specimens, and gave matched-well results in comparison with commercially available enzyme-linked immunosorbent assay (ELISA) method.
Co-reporter:Shuzhen Lv, Zhenzhen Lin, Kangyao Zhang, Minghua Lu, Dianping Tang
Analytica Chimica Acta 2017 Volume 964(Volume 964) pp:
Publication Date(Web):29 April 2017
DOI:10.1016/j.aca.2017.02.004
•We designed an in-situ amplified potentiometric immunosensor for detecting prostate-specific antigen.•Polyion oligonucleotide-decorated gold nanoparticles were used as the signal-generation tags.•Oligonucleotides were favorable for tunable surface charge density.Methods based on nanostructures have been developed for potentiometric immunosensors, but most involve low sensitivity or weak signal output and are unsuitable for routine use in diagnosis. Herein, we devise an in-situ signal-amplification strategy for enhanced electrical readout of potentiometric immunosensor toward target prostate-specific antigen (PSA, one kind of cancer biomarkers), based on polyion oligonucleotide-labeled gold nanoparticles (AuNPs). To decrease the background signal, monoclonal anti-human PSA capture antibody was covalently conjugated onto an activated glassy carbon electrode via typical carbodiimide coupling. AuNPs heavily functionalized with the polyion oligonucleotides and polyclonal anti-PSA detection antibodies (pAb2-AuNP-DNA) were utilized as the signal-generation nanotags. In the presence of target PSA, a sandwich-type immunoreaction was executed between capture antibody and detection antibody on the electrode. The detectable signal derived from the shift in the electric potential as a result of the change in the surface charge before and after the antigen-antibody reaction. With target PSA increased, the captured pAb2-AuNP-DNA to the electrode accompanying detection antibody increased, thereby resulting in the change of the electrode potential. Due to numerous polyion oligonucleotides with the negative charge, the signal readout amplified. Under the optimal conditions, the shift in the output potential was proportional to the logarithm of target PSA concentration and displayed a dynamic linear range from 0.05 to 20 ng mL−1 with a detection limit of 13.6 pg mL−1. An intermediate precision of ≤13.2% was accomplished with the batch-to-batch identification. The selectivity was acceptable. The method accuracy was evaluated for human serum specimens, and gave the consistent results between the potentiometric immunosensor and the referenced enzyme-linked immunosorbent assay (ELISA).Download high-res image (257KB)Download full-size image
Co-reporter:Zhenzhen Lin;Shuzhen Lv;Kangyao Zhang
Journal of Materials Chemistry B 2017 vol. 5(Issue 4) pp:826-833
Publication Date(Web):2017/01/25
DOI:10.1039/C6TB03042D
This work designs a simple low-cost visual fluorescence immunoassay for disease-related biomarkers (carcinoembryonic antigen, CEA, used as a model protein) in biological fluids, based on the structural and optical transformation of CdTe quantum dots (QDs) immobilized on paper induced by dissolved silver ions (Ag+) from silver nanoparticles (AgNPs) via a cation-exchange reaction. A sandwich-type immunoreaction was initially carried out in a removable polystyrene high-binding microplate coated with monoclonal anti-CEA capture antibody by using AgNP-labeled polyclonal anti-CEA antibody as the detection antibody. Thereafter, the carried AgNPs accompanying the sandwiched immunocomplexes were dissolved by acid to release numerous silver ions, which induced the ion-exchange reaction with the immobilized CdTe QDs on the paper (attached onto the microplate lid) for the Cd-to-Ag transformation, thus resulting in the quenching of the visual fluorescence from the CdTe QDs owing to Ag2Te formation. Under optimal conditions, the fluorescence intensity decreased with the increasing CEA concentration from 0.02 to 50 ng mL−1 with a detection limit of 5.6 pg mL−1. Further, a visual assay based on a CdTe QD-based paper sensor was developed for CEA detection, and 5.0 pg mL−1 CEA could be discriminated with the naked eye. In addition, our strategy displayed high specificity, good reproducibility and acceptable accuracy for analyzing human serum specimens with consistent results obtained using the commercialized enzyme-linked immunosorbent assay (ELISA) method.
Co-reporter:Guang-Zhou Li
Journal of Materials Chemistry B 2017 vol. 5(Issue 28) pp:5573-5579
Publication Date(Web):2017/07/19
DOI:10.1039/C7TB00670E
Herein, we design a simple and portable biosensing platform for the quantitative detection of cocaine based on target-triggered glucose release from a TiO2 nanotube array (TiNTA) with a glucometer readout. Initially, single-stranded DNA1 and DNA2 were covalently conjugated to the TiNTA and gold nanoparticle (AuNP), respectively. In the presence of cocaine aptamer and glucose, the immobilized DNA1 on the TiNTA and the labeled DNA2 on the AuNP simultaneously hybridized with the adjacent area of the aptamer, and gated the glucose molecules in the nanotubes. Upon the introduction of cocaine, the aptamer specifically reacted with an analyte to form the target–aptamer complex, thus resulting in the dissociation of DNA1–TiNTA and DNA2–AuNP to release glucose molecules from the nanotubes. The as-released glucose molecules could be determined on a personal glucometer (PGM). The experimental results revealed that the PGM signal increased with increasing cocaine concentration, and exhibited a wide linear range of 10–600 nM with a detection limit of 5.2 nM. Intra- and inter-assay relative standard deviations with identical batches were less than 9.3% and 12.7%, respectively. The specificity, reproducibility, and stability of our strategy were acceptable. Importantly, this concept offers promise for a rapid, simple, low-cost, and user-friendly analysis of small-molecular cocaine.
Co-reporter:Qian Zhou;Youxiu Lin;Minghua Lu
Journal of Materials Chemistry B 2017 vol. 5(Issue 48) pp:9600-9607
Publication Date(Web):2017/12/14
DOI:10.1039/C7TB02354E
This work designs a new photoelectrochemical (PEC) sensing system for the detection of carcinoembryonic antigens (CEAs) using bismuth ferrite (BiFeO3) nanostructures as photoactive materials, accompanied by the target-controlled release of glucose from multifunctional mesoporous silica nanoparticles (MSNs) for signal amplification. Glucose molecules were gated in the pores via the hybridization of a CEA aptamer with anchor DNA (aDNA, modified on the mesoporous silica nanoparticles). Upon the addition of the target CEA, the analyte competitively reacted with the aptamer to open the gate, thus resulting in the release of glucose molecules from the MSNs. Based on the oxidization of glucose in the presence of glucose oxidase, the as-generated enzymatic product (H2O2) served as an electron acceptor to enhance the photocurrent generated by the BiFeO3 nanostructures under visible light irradiation. In this way, an in situ amplified photocurrent could be achieved in that the low-concentration target CEA could cause the release of numerous glucose molecules. Experimental results suggested that the photocurrent obtained from the BiFeO3-based photoactive materials increased with increasing CEA concentration and showed a good linear dependence on the logarithm of the CEA level from 5.0 pg mL−1 to 50 ng mL−1 under optimal conditions. Additionally, the BiFeO3-based PEC sensing platform also showed good stability and favorable selectivity, and satisfactory accuracy for CEA detection in human serum specimens in comparison with a reference CEA ELISA kit. The good analytical performance of the BiFeO3-based PEC sensing method makes it a promising tool for the efficient, low-cost and convenient detection of CEAs in disease diagnosis.
Co-reporter:Jing Lv;Ying Tang;Dianyong Tang;Jin Zhang
Analytical Methods (2009-Present) 2017 vol. 9(Issue 1) pp:117-123
Publication Date(Web):2016/12/22
DOI:10.1039/C6AY02806C
Herein, a new electrochemical sensing protocol was designed for ultrasensitive detection of copper(II) (Cu2+) at the attomolar level based on target-induced click conjugation using horseradish peroxidase (HRP) as an indicator and gold nanoparticle (AuNP) as an enhancer. The click conjugation was carried out between the immobilized azido-DNA on the electrode and alkynyl-DNA/HRP-labeled AuNP. With the help of sodium ascorbate, target Cu2+ ion was initially reduced into Cu+, and the as-produced Cu+ could catalyze the azide–alkyne click reaction. Accompanying gold nanoparticles, the carried HRP molecules could electrochemically reduce the substrate (H2O2); this resulted in a strong electronic signal. The digital readout was relative to the amount of the peroxidase and indirectly reflected the Cu2+ concentration in the testing media. Under optimal conditions, the as-prepared sensor exhibited good electrochemical response towards Cu2+ in the 1.0 aM to 10 μM dynamic working range with a 0.38 aM detection limit. This methodology also displayed a high selectivity for Cu2+ relative to other potentially interfering ions due to the specific Cu+-induced azide–alkyne click reaction, and was applicable for monitoring Cu2+ in real river samples. Our strategy has a good potential for use in environmental surveys.
Co-reporter:Zhuangqiang Gao;Shuzhen Lv;Mingdi Xu
Analyst (1876-Present) 2017 vol. 142(Issue 6) pp:911-917
Publication Date(Web):2017/03/13
DOI:10.1039/C6AN02722A
Developing simple, high-efficiency non-enzyme bioassays is of great importance for modern analytical systems, but remains a significant challenge. One promising route is to utilize highly efficient nanocatalysts with the exposure of active crystal facets. Herein, we for the first time propose a novel colorimetric immunoassay for the ultrasensitive detection of the human prostate-specific antigen (PSA) based on using a unique type of nanolabel – high-index {hk0} faceted platinum concave nanocubes (HIF-Pt-CNCs). The proposed HIF-Pt-CNCs exhibit superior peroxidase-like catalytic activity that is ∼1500- and ∼4-fold higher than that of natural horseradish peroxidase and Pt nanospheres, respectively, and thereby can provide powerful signal amplification by catalyzing the oxidation of peroxidase substrates in the presence of hydrogen peroxide. Using the HIF-Pt-CNC-labelled anti-PSA detection antibody as a signal probe, the immunoassay is carried out in anti-PSA capture antibody-immobilized microplate wells in a sandwich-type detection mode. Under optimal conditions, the developed immunoassay is able to achieve high sensitivity and specificity for PSA detection in a linear range of 20–2000 pg mL−1 and with an ultralow detection limit of 0.8 pg mL−1, which is much lower than that of conventional enzyme-linked immunosorbent assay (ELISA). Moreover, the method is validated for the analysis of 10 PSA clinical serum specimens, and the results agree very well with those obtained by using a commercialized ELISA kit. Therefore, this new, facile and efficient immunoassay is a promising technique with potential applications in medical science research and clinical diagnosis.
Co-reporter:Dianping Tang;Jingjing Ren;Minghua Lu
Analyst (1876-Present) 2017 vol. 142(Issue 24) pp:4794-4800
Publication Date(Web):2017/12/04
DOI:10.1039/C7AN01459G
Herein, a simple and feasible electrochemical immunosensing method for simultaneous voltammetric detection of two immunoglobulin proteins, human IgG (HIgG) and rabbit IgG (RIgG), was developed using two distinguishable signal-generation tags on the same electrode. The immunosensor was prepared by immobilizing two Fab antibody fragments on a gold electrode. After this, Cu and Cd nanocrystals, as nanotags, were synthesized and functionalized with identical detection antibodies. Transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR) were employed to characterize the Cu and Cd nanocrystals. The covalently modified electrode with the Fab antibody fragments through the Au-thiolate bond (to dispel the non-specific adsorption) was investigated via scanning electron microscopy (SEM). After the sandwiched immunoreaction, the antibody-modified nanocrystals were captured on the immunosensor, which could be interrogated in pH 3.5 HCl using square-wave anodic stripping voltammetry. Experimental results also indicated that the multiplexed immunoassay enabled the simultaneous detection of HIgG and RIgG in a single run with the similar linear range from 0.01 to 10 ng mL−1, and the limits of detection (LODs) towards two analytes could be as low as 3.4 pg mL−1 (at 3σ). Acceptable assay results on precision, reproducibility, specificity, and method accuracy were also acquired. Importantly, the newly designed strategy avoided cross-talk and enzymatic introduction as compared to conventional electrochemical immunoassays, thus exhibiting a promising potential in clinical applications.
Co-reporter:Qian Zhou, Youxiu Lin, Jian Shu, Kangyao Zhang, Zhenzhong Yu, Dianping Tang
Biosensors and Bioelectronics 2017 Volume 98(Volume 98) pp:
Publication Date(Web):15 December 2017
DOI:10.1016/j.bios.2017.06.033
•A photoelectrochemical sensing platform was designed for PSA detection.•Reduced graphene oxide-functionalized FeOOH is used as the photoactive material.•Bioresponsive controlled glucose release from mesoporous silica is utilized for the signal amplification.A new and signal-on photoelectrochemical (PEC) sensing platform was successfully designed for the sensitive detection of prostate-specific antigen (PSA), using reduced graphene oxide- functionalized iron oxyhydroxide (FeOOH-rGO) as the photoactive material, accompanying target-responsive controlled release system to achieve the signal amplification. Introduction of rGO as electron mediator greatly facilitated the electron transfer from FeOOH to electrode under visible light, which inhibited the electron-hole recombination to enhance the photo-activity of FeOOH-rGO. Additionally, the bioresponsive release system was controlled via the reaction of target PSA with the aptamer capped glucose-loading mesoporous silica nanoparticle (MSN) to release numerous glucose molecules (as the electron donors) for the amplification of the photocurrent generated from FeOOH-rGO. Thus, more glucose molecules could be released and enhanced photocurrents could be obtained with the increasing PSA concentrations. Experimental results showed that the photocurrents of the PEC sensing platform were linearly dependent on the logarithm of PSA concentrations from 1.0 pg/mL to 100 ng/mL. Moreover, the PEC sensing system afforded good stability and specificity, and its accuracy matched well with the commercial PSA enzyme-linked immunosorbent assay (ELISA) kit. The excellent performance of the PEC sensing platform indicated its promising prospect as a useful tool for PSA detection in practical application.
Co-reporter:Wenqiang Lai, Qiaohua Wei, Mingdi Xu, Junyang Zhuang, Dianping Tang
Biosensors and Bioelectronics 2017 Volume 89(Part 1) pp:645-651
Publication Date(Web):15 March 2017
DOI:10.1016/j.bios.2015.12.035
•We developed a new colorimetric immunoassay for aflatoxin B1.•Two-dimensional MnO2 nanoflakes were used as enzymatic mimics.•Enzyme cascade amplification strategy was utilized for immunoassay development.A new colorimetric immunosensing platform accompanying enzyme cascade amplification strategy was fabricated for quantitative screening of small-molecular mycotoxins (aflatoxin B1, AFB1 used in this case) coupling with enzyme-controlled dissolution of MnO2 nanoflakes. The visual colored assay was executed by high-efficient MnO2–3,3′,5,5′-tetramethylbenzidine (TMB) system (blue). In the presence of ascorbic acid, MnO2 nanoflakes were dissolved into Mn2+ ions, thus resulting in a perceptible color change from blue to colorless. The reaction could be weakened through ascorbate oxidase to catalyze ascorbic acid into dehydroascorbic acid, which indirectly depended on the concentration of ascorbate oxidase. By using ascorbate oxidase/ anti-AFB1 antibody-labeled gold nanoparticles, a novel competitive-type colorimetric enzyme immunoassay was developed for detection of AFB1 on AFB1-bovine serum albumin (BSA)-conjugated magnetic beads. Upon addition of target AFB1, the analyte competed with the conjugated AFB1-BSA on the magnetic beads for the labeled anti-AFB1 antibody on the gold nanoparticles. Under optimal conditions, the absorbance decreased with increasing target AFB1 within the dynamic range of 0.05–150 ng mL−1 with a detection limit of 6.5 pg mL−1 at the 3Sblank level. The precision and specificity of the MnO2–TMB-based immunosensing system were acceptable. In addition, method accuracy was further validated for monitoring spiked peanut samples, giving results matched well with those obtained from commercialized AFB1 ELISA kit.
Co-reporter:Youxiu Lin, Qian Zhou, Juan Li, Jian Shu, Zhenli Qiu, Yuping Lin, and Dianping Tang
Analytical Chemistry 2016 Volume 88(Issue 1) pp:1030
Publication Date(Web):November 26, 2015
DOI:10.1021/acs.analchem.5b04005
A novel flow-through microfluidic device based on a magneto-controlled graphene sensing platform was designed for homogeneous electronic monitoring of pyrophosphatase (PPase) activity; enzymatic hydrolysate-induced release of inorganic copper ion (Cu2+) from the Cu2+-coordinated pyrophosphate ions (Cu2+–PPi) complex was assessed to determine enzyme activity. Magnetic graphene nanosheets (MGNS) functionalized with negatively charged Nafion were synthesized by using the wet-chemistry method. The Cu2+–PPi complexes were prepared on the basis of the coordination reaction between copper ion and inorganic pyrophosphate ions. Upon target PPase introduction into the detection system, the analyte initially hydrolyzed pyrophosphate ions into phosphate ions and released the electroactive copper ions from Cu2+–PPi complexes. The released copper ions could be readily captured through the negatively charged Nafion on the magnetic graphene nanosheets, which could be quantitatively monitored by using the stripping voltammetry on the flow-through detection cell with an external magnet. Under optimal conditions, the obtained electrochemical signal exhibited a high dependence on PPase activity within a dynamic range from 0.1 to 20 mU mL–1 and allowed the detection at a concentration as low as 0.05 mU mL–1. Coefficients of variation for reproducibility of the intra-assay and interassay were below 7.6 and 9.8%, respectively. The inhibition efficiency of sodium fluoride (NaF) also received good results in pyrophosphatase inhibitor screening research. In addition, the methodology afforded good specificity and selectivity, simplification, and low cost without the need of sample separations and multiple washing steps, thus representing a user-friendly protocol for practical utilization in a quantitative PPase activity.
Co-reporter:Youxiu Lin, Qian Zhou, Dianping Tang, Reinhard Niessner, Huanghao Yang, and Dietmar Knopp
Analytical Chemistry 2016 Volume 88(Issue 15) pp:7858
Publication Date(Web):June 27, 2016
DOI:10.1021/acs.analchem.6b02124
Mycotoxins, highly toxic secondary metabolites produced by many invading species of filamentous fungi, contaminate different agricultural commodities under favorable temperature and humidity conditions. Herein, we successfully devised a novel signal-on photoelectrochemical immunosensing platform for the quantitative monitoring of mycotoxins (aflatoxin B1, AFB1, used as a model) in foodstuffs on the basis of silver nanolabels-assisted ion-exchange reaction with CdTe quantum dots (QDs) mediated hole-trapping. Initially, a competitive-type immunoreaction was carried out on a high-binding microplate by using silver nanoparticle (AgNP)-labeled AFB1–bovine serum albumin (AFB1–BSA) conjugates as the tags. Then, the carried AgNPs with AFB1–BSA were dissolved by acid to release numerous silver ions, which could induce ion-exchange reaction with the CdTe QDs immobilized on the electrode, thus resulting in formation of surface exciton trapping. Relative to pure CdTe QDs, the formed exciton trapping decreased the photocurrent of the modified electrode. In contrast, the detectable photocurrent increased with the increase of target AFB1 in a dynamic working range from 10 pg mL–1 to 15 ng mL–1 at a low limit of detection (LOD) of 3.0 pg mL–1 under optimal conditions. In addition, the as-prepared photoelectrochemical immunosensing platform also displayed high specificity, good reproducibility, and acceptable method accuracy for detecting naturally contaminated/spiked blank peanut samples with consistent results obtained from the referenced enzyme-linked immunosorbent assay (ELISA) method.
Co-reporter:Qian Zhou, Youxiu Lin, Mingdi Xu, Zhuangqiang Gao, Huanghao Yang, and Dianping Tang
Analytical Chemistry 2016 Volume 88(Issue 17) pp:8886
Publication Date(Web):August 1, 2016
DOI:10.1021/acs.analchem.6b02543
Herein, gold–silver bimetallic nanoclusters (Au–Ag NCs) with the high fluorescent intensity were first synthesized successfully and utilized for the fabrication of sensitive and specific sensing probes toward inorganic pyrophosphatase (PPase) activity with the help of copper ion (Cu2+) and inorganic pyrophosphate ion (PPi). Cu2+ was used as the quencher of fluorescent Au–Ag NC, while PPi was employed as the hydrolytic substrate of PPase. The system consisted of PPi, Cu2+ ion, and bovine serum albumin (BSA)-stabilized Au–Ag NC. The detection was carried out by enzyme-induced hydrolysis of PPi to liberate copper ion from the Cu2+-PPi complex. In the absence of target PPase, free copper ions were initially chelated with inorganic pyrophosphate ions to form the Cu2+-PPi complexes via the coordination chemistry, thus preserving the natural fluorescent intensity of the Au–Ag NCs. Upon addition of target PPase into the detection system, the analyte hydrolyzed PPi into phosphate ions and released Cu2+ ion from the Cu2+-PPi complex. The dissociated copper ions readily quenched the fluorescent signal of Au–Ag NCs, thereby resulting in the decrease of fluorescent intensity. Under optimal conditions, the detectable fluorescent intensity of the as-prepared Au–Ag NCs was linearly dependent on the activity of PPase within a dynamic linear range of 0.1–30 mU/mL and allowed the detection at a concentration as low as 0.03 mU/mL at the 3sblank criterion. Good reproducibility (CV < 8.5% for the intra-assay and interassay), high specificity, and long-term stability (90.1% of the initial signal after a storage period of 48 days) were also received by using our system toward target PPase activity. In addition, good results with the inhibition efficiency of sodium fluoride were obtained in the inhibitor screening research of pyrophosphatase. Importantly, this system based on highly enhanced fluorescent Au–Ag NCs offer promise for simple and cost-effective screening of target PPase activity without the needs of sample separation and multiple washing steps.
Co-reporter:Jian Shu, Zhenli Qiu, Qian Zhou, Youxiu Lin, Minghua Lu, and Dianping Tang
Analytical Chemistry 2016 Volume 88(Issue 5) pp:2958
Publication Date(Web):January 29, 2016
DOI:10.1021/acs.analchem.6b00262
Herein a novel split-type photoelectrochemical (PEC) immunosensing platform was designed for sensitive detection of low-abundance biomarkers (prostate-specific antigen, PSA, used in this case) by coupling a peroxyoxalate chemiluminescence (PO-CL) self-illuminated system with digital multimeter (DMM) readout. The PEC detection device consisted of a capacitor/DMM-joined electronic circuit and a PO-CL-based self-illuminated cell. Initially, reduced graphene oxide-doped BiVO4 (BiVO4-rGO) photovoltaic materials with good photoelectric properties was integrated into the capacitor/DMM-joined circuit for photocurrent generation in the presence of hydrogen peroxide (H2O2, as the hole-trapping reagent). A sandwich-type immunoreaction with target PSA was carried out in capture antibody-coated microplates by using glucose oxidase/detection antibody-conjugating gold nanoparticle (pAb2-AuNP-GOx). Accompanying the sandwiched immunocomplex, the labeled GOx could oxidize glucose to produce H2O2. The as-generated H2O2 could act as the coreaction reagent to trigger the chemiluminescence of the peroxyoxalate system and the PEC reaction of the BiVO4-rGO. Meanwhile, the self-illuminated light could induce photovoltaic material (BiVO4-rGO) to produce a voltage that was utilized to charge an external capacitor. With the switch closed, the capacitor could discharge through the DMM and provide an instantaneous current. Different from conventional PEC immunoassays, the as-generated photoelectron was stored in the capacitor and released instantaneously to amplify the photocurrent. Under the optimal conditions, the transient current increased with the increasing target PSA concentration in the dynamic working range from 10 pg mL–1 to 80 ng mL–1 with a detection limit (LOD) of 3 pg mL–1. This work demonstrated for the first time that the peroxyoxalate CL system could be used as a suitable substitute of physical light source to apply in PEC immunoassay. In addition, this methodology afforded good reproducibility, precision, and high specificity, and the method accuracy matched well with the commercial PSA ELISA kit. Importantly, the developed split-type photoelectrochemical immunoassay could not only avoid the interfering of the biomolecules relative to the photovoltaic materials but also eliminate the need of an exciting light source and expensive instrumentation, thus representing a user-friendly and low-cost assay protocol for practical utilization in quantitative low-abundance proteins.
Co-reporter:Jiashi Lin and Dianping Tang
Analytical Methods 2016 vol. 8(Issue 20) pp:4069-4074
Publication Date(Web):20 Apr 2016
DOI:10.1039/C6AY00897F
A simple and low-cost electrochemical immunosensing platform with a personal glucometer (PGM)-based signal readout device was developed for the quantitative detection of human carbohydrate antigen 125 (CA 125) using invertase for the hydrolysis of sucrose. To achieve a high sensitivity, branched platinum nanowires (BPtNWs) synthesized by a wet-chemistry method were utilized for the conjugation of invertase and anti-CA 125 secondary antibody. The immuno-reaction was carried out on an anti-CA 125 capture antibody-coated polystyrene microtiter plate with a sandwich-type assay mode, using the biofunctionalized BPtNWs as signal-generation tags. Accompanying the formation of the sandwiched immuno complexes, the carried invertase with the BPtNWs hydrolyzed sucrose into glucose and fructose. The glucose produced could be determined for quantification using a portable personal glucometer. By integrating the secondary antibody and invertase with branched platinum nanowires, this method displayed an excellent sensitivity with a detection limit of 23 mU mL−1 CA 125. The selective experiments revealed that the developed system was specific for the target CA 125, even coexisting with a high concentration of other biomarkers. Finally, analysis of human serum samples was also performed, showing that our strategy was reliable and had great potential application in early clinical diagnostics.
Co-reporter:Qian Zhou, Youxiu Lin, Yuping Lin, Qiaohua Wei, Guonan Chen, Dianping Tang
Biosensors and Bioelectronics 2016 Volume 78() pp:236-243
Publication Date(Web):15 April 2016
DOI:10.1016/j.bios.2015.11.055
•We designed an electrochemical biosensor for lead ion.•Hemin/G-quadruplex was used as NADH oxidase and HRP-mimicking DNAzyme.•Porous Au–Pd bimetallic nanostructures were employed as nanocarriers.In this work, a sensitive and specific electrochemical biosensor for lead ion (Pb2+) detection was developed by coupling with synergetic catalysis of porous Au–Pd bimetallic nanoparticles and hemin/G-quadruplex-based DNAzyme. In the presence of target Pb2+, the substrate strand was cleaved and the enzyme strand was released. Subsequently, G-rich DNA-labeled Au–Pd bimetallic nanoparticle was linked with the released enzyme strand through the helper DNA. Upon addition of hemin, a large number of hemin/G-quadruplex-based DNAzyme molecules were formed on the electrode to serve as nicotinamide adenine dinucleotide hydrogen (NADH) oxidase and peroxidase mimics. DNAzyme could catalyzed the reduction of H2O2, generated from NADH in the presence of O2, to produce an electrochemical signal when using thionine as the electron mediator. Introduction of porors Au–Pd bimetallic nanoparticles could enhance the detectable signal and cause the increase in the sensitivity. Experimental results showed that the variations (∆I) in the cathodic peak currents of the biosensor were linearly dependent on target Pb2+ concentrations from 1.0 pM to 100 nM with a detection limit (LOD) of 0.34 pM. The excellent performance of the sensing platform indicated its promising prospect as a valuable tool for simple and cost-effective Pb2+ detection in practical application.
Co-reporter:Zhenli Qiu, Jian Shu, Guixiao Jin, Mingdi Xu, Qiaohua Wei, Guonan Chen, Dianping Tang
Biosensors and Bioelectronics 2016 Volume 77() pp:681-686
Publication Date(Web):15 March 2016
DOI:10.1016/j.bios.2015.10.044
•We designed a simple sensor for Hg2+ detection with glucometer readout.•The assay was carried out based on thymine–Hg2+–thymine coordination chemistry.•Invertase-labeling gold-dendrimer nanostructures were utilized for signal amplification.A simple, low-cost transducer with glucometer readout was designed for sensitive detection of mercury(II) (Hg2+), coupling with thymine–Hg2+–thymine (T–Hg2+–T) coordination chemistry and invertase-functionalized gold-dendrimer nanospheres for the signal amplification. Initially, nanogold-encapsulated poly(amidoamine) dendrimers (Au DENs) were synthesized by in-situ reduction of gold(III). Thereafter, the as-prepared Au DENs were utilized for the labeling of invertase and T-rich signal DNA probe. In the presence of target Hg2+, the functionalized Au DENs were conjugated to capture DNA probe-modified electrode via T–Hg2+–T coordination chemistry. Accompanying the Au DENs, the labeled invertase could hydrolyze sucrose into glucose, which could be quantitatively monitored by an external personal glucometer (PGM). The PGM signal increased with the increasing target Hg2+ in the sample. Under the optimal conditions, our designed sensing platform exhibited good PGM responses toward target Hg2+, and allowed the detection of Hg2+ at a concentration as low as 4.2 pM. This sensing system also displayed remarkable specificity relative to target Hg2+ against other competing ions, and could be applied for reliable monitoring of spiked Hg2+ into the environmental water samples with satisfactory results. With the advantages of cost-effectiveness, simplicity, portability, and convenience, our strategy provides a tremendous potential to be a promising candidate for point-of-use monitoring of non-glucose targets by the public.
Co-reporter:Zhenli Qiu, Dianyong Tang, Jian Shu, Guonan Chen, Dianping Tang
Biosensors and Bioelectronics 2016 Volume 75() pp:108-115
Publication Date(Web):15 January 2016
DOI:10.1016/j.bios.2015.08.026
•We designed a new impedimetric sensor for Hg2+ detection.•The signal was amplified by enzyme-triggered formation of enzyme-tyramine concatamer.•Enzymatic biocatalytic precipitation was utilized for impedimetric detection.•Nanogold-functionalized dendrimer was used as the affinity support.A new impedimetric sensing strategy based on enzyme-triggered formation of enzyme-tyramine concatamers on the nanogold-functionalized poly(amidoamine) (PAMAM) dendrimer was designed for sensitive detection of mercury(II) (Hg2+) ion, coupling with enzymatic biocatalytic precipitation towards 4-choloro-1-naphthol (4-CN) on thymine (T)-rich single-stranded DNA1-modified electrode. Initially, nanogold–decorated PAMAM dendrimer (AuNP–PAMAM) was synthesized by the in-situ reduction method, and then functionalized with horseradish peroxidase (HRP) and another T-rich oligomer (DNA2). Upon target Hg2+ introduction, probe DNA2 on the AuNP–PAMAM bound to the DNA1 on the electrode owing to the T–Hg2+–T coordination chemistry between the two DNA strands. Accompanying the AuNP–PAMAM, the carried HRP could trigger the formation of HRP–tyramine concatamer via the classical tyramine signal amplification strategy in the presence of HRP–tyramine conjugates and hydrogen peroxide. The concatenated HRP molecules in the concatamer catalyzed the 4-CN oxidation to produce an insoluble precipitation on the electrode, thereby resulting in the local alteration in the conductivity. Under optimal conditions, two signal-generation tags including HRP–AuNP–DNA2 and HRP–AuNP–PAMAM–DNA2 with or without tyramine signal amplification strategy (i.e., four schemes) were used for impedimetric detection of target Hg2+ on the basis of the same assay format. A low detection limit (LOD) of 0.4 pM and a wide dynamic working range of 0.001–100 nM Hg2+ by using HRP–AuNP–PAMAM–DNA2 with tyramine signal amplification strategy were obtained in comparison with those of other strategies. The assay had a good repeatability and showed an intermediate precision of down to 9.6%. In addition, the methodology also exhibited high specificity and selectivity towards target Hg2+ against other metal ions, and was applicable for monitoring Hg2+ in the spiked drinking water samples.
Co-reporter:Juan Tang, Yapei Huang, Cengceng Zhang, Huiqiong Liu, Dianping Tang
Biosensors and Bioelectronics 2016 Volume 86() pp:386-392
Publication Date(Web):15 December 2016
DOI:10.1016/j.bios.2016.06.080
•An facile impedimetric immunoassay was developed for OTA based on instant catalyst.•The instant catalyst can be formed on the immunosensing platform in 1 min.•The instant catalyst could catalyze the 4-CN oxidation without H2O2.•The PAMAM can load with multiple Mn2+ ions.A new impedimetric immunosensor for the fast determination of ochratoxin A (OTA) in food samples was developed based on the instant catalyst as enhancer. Initially, the signal tags were prepared via co-immobilization of anti-OTA antibody and amine-terminated dendrimer (PAMAM) on the graphene oxide nanosheets through the covalent interaction, which were utilized as a good platform for combining manganese ion (anti-OTA-GO-PAMAM-Mn2+). Upon target OTA introduction, a competitive-type immunoreaction was implemented between the analyte and the immobilized OTA-BSA on the electrode for the anti-OTA antibody on the graphene oxide nanosheets labels. After a competitive immunoassay format, the anti-OTA-GO-PAMAM-Mn2+ were captured onto the electrode surface, which could induce the in situ formation of MnO2via classical redox reaction between Mn2+ and KMnO4 on the immunesensing platform. Moreover, the generated MnO2 nanoparticles act as efficient catalyst could catalyze the 4-chloro-1-naphthol (4-CN) oxidation without H2O2 to generate an insoluble precipitation on the platform. Under the optimal conditions, the instant catalyst based impedimetric immunosensor displayed a wide dynamic working range between 0.1 pg mL−1 and 30 ng mL−1. The detection limit (LOD) of the assay was 0.055 pg mL−1. The developed method exhibited high selectivity and can be used for the determination of OTA in real red wine samples.
Co-reporter:Juan Tang, Yapei Huang, Huiqiong Liu, Cengceng Zhang, Dianping Tang
Biosensors and Bioelectronics 2016 Volume 79() pp:508-514
Publication Date(Web):15 May 2016
DOI:10.1016/j.bios.2015.12.097
•We designed a new glucometer-based immunoassay for detection of aflatoxin B1.•Glucose-encapsulated nanoliposomes were used as the labels.•Surfactant-responsive glucose release was utilized for the signal generation.Methods based on surfactant-responsive controlled release systems of cargoes from nanocontainers have been developed for bioanalytical applications, but most were utilized for drug delivery and a few reports were focused on immunoassays. Herein we design an in situ amplified immunoassay protocol for high-efficient detection of aflatoxins (aflatoxin B1, AFB1 used in this case) based on surfactant-responsive cargo release from glucose-encapsulated liposome nanocarriers with sensitivity enhancement. Initially, biotinylated liposome nanocarrier encapsulated with glucose was synthesized using a reverse-phase evaporation method. Thereafter, the nanocarrier was utilized as the signal-generation tag on capture antibody-coating microplate through classical biotin-avidin linkage after reaction with biotinylated detection antibody. Upon addition of buffered surfactant (1X PBS-Tween 20 buffer) into the medium, the surfactant immediately hydrolyzed the conjugated liposome, and released the encapsulated glucose from the nanocarriers, which could be quantitatively determined by using a low-cost personal glucometer (PGM). The detectable signal increased with the increment of target analyte. Under the optimal conditions, the assay could allow PGM detection toward target AFB1 as low as 0.6 pg mL−1 (0.6 ppt). Moreover, the methodology also showed good reproducibility and high specificity toward target AFB1 against other mycotoxins and proteins, and was applicable for quantitatively monitoring target AFB1 in the complex systems, e.g., naturally contaminated/spiked peanut samples and serum specimens, with the acceptable results. Taking these advantages of simplification, low cost, universality and sensitivity, our design provides a new horizon for development of advanced immunoassays in future point-of-care testing.
Co-reporter:Dianping Tang;Li Hou
Microchimica Acta 2016 Volume 183( Issue 10) pp:2705-2711
Publication Date(Web):2016 October
DOI:10.1007/s00604-016-1916-2
The authors report on a new electrochemical aptasensing strategy for the determination of adenosine - 5’-triphosphate (ATP) at picomolar levels. First, manganese dioxide (MnO2) nanosheets with an average size of ~70 nm were synthesized via a hot-injection method on the basis of reaction between potassium permanganate and the cationic detergent cetyltrimethylammonium bromide. The resulting MnO2 nanosheets were then immobilized onto a pretreated screen-printed carbon electrode which readily binds the ferrocene-labeled ATP aptamer through the van der Waals force between the nucleobases and the basal plane of the nanoflakes. The immobilized ferrocene-aptamer conjugates activates the electrical contact with the electrode and produces a strong signal in the potentials scanned (0.0 to 1.0 V vs. Ag/AgCl). Upon addition of ATP, it will react with the aptamer and cause the dissociation of the ferrocene-aptamer from the nanosheets, this resulting in a decrease in the electrical signal. Under optimal conditions, this platform exhibits a detection limit as low as 0.32 nM of ATP. The repeatability and intermediate precision is below 10.7 % at a 10 nM concentration level. The method was applied to analyze blank fetal calf serum spiked with ATP, and the recoveries (at 3 concentration levels) ranged between 91.3 and 118 %. This detection scheme is rapid, simple, cost-effective, and does not require extensive sample preparation or multiple washing steps.
Co-reporter:Jian Shu, Zhenli Qiu, Zhenzhen Lin, Guoneng Cai, Huanghao Yang, and Dianping Tang
Analytical Chemistry 2016 Volume 88(Issue 24) pp:
Publication Date(Web):November 23, 2016
DOI:10.1021/acs.analchem.6b04461
Photoelectrochemical (PEC) measurement has been developed rapidly for bioanalysis in recent years. However, the actual application for most existed PEC bioanalytical systems is still a challenge because the perfect solutions for sensing surface design, high-throughput detection, and portability are lacked. To successfully overcome these limitations and realize accurate, continuous screening and assessing on prognostic indicator of early stage cancer on the spot, an innovative and portable semiautomated support power-free photoelectrochemical (SP-PEC) immunosensing platform consisted with a miniature semiautomatic injection system and digital multimeter (DMM) readout is designed (prostate specific antigen, PSA, was used as the proof-of-concept analyte). Decahedral BiVO4 that decorated with Au nanocrystal on {010} facets (Au-BiVO4) by photodeposition is used as the photoanode materials to produce photocurrent signal under irradiation of micro laser light (5.0 w, λ ≥ 380 nm). The monoclonal anti-PSA capture antibody (mAb1)-functionalized Fe3O4 magnetic nanobeads (mAb1-MN) and glucose oxidase (GOx)/monoclonal detection antibody (mAb2)-conjugated gold nanoparticle (GOx-AuNP-mAb2) are employed as immunosensing probe and signal probe, respectively. The H2O2 as an excellent holes scavenger that in suit generated from GOx oxidization glucose substrate significantly amplifies the photocurrent. The variation of instantaneous current value that registered as the signal of the immunoassay increases linearly with the logarithm of target PSA concentration increasing in a wide range from 10 pg mL–1 to 100 ng mL–1 with a low detection limit (LOD) of 4.0 pg mL–1. The SP-PEC immunosensing platform not only simplifies the assay process, but also improves detecting efficiency. The semiautomatic and portable SP-PEC analysis device allows analysis on spot and high-throughput continuous detection. Additional, we also gain deep insight into the relations between the specific shape as well as Au nanocrystal decoration and PEC activity and speculate the possible enhancement mechanisms of Au-BiVO4. Therefore, the present work not only develops a flexible SP-PEC biosensor platform for rapid and continuous detection, but also provides a possible route for designing high performance photoelectric materials.
Co-reporter:Qian Zhou, Youxiu Lin, Yuping Lin, Qiaohua Wei, Guonan Chen, Dianping Tang
Talanta 2016 Volume 146() pp:23-28
Publication Date(Web):1 January 2016
DOI:10.1016/j.talanta.2015.08.035
•We design a new and label-free electrochemical aptasensor for quantitative detection of ATP.•Homogeneous reaction between target and aptamer was constructed.•Target-induced hybridization chain reaction was use for signal amplification.•Silver nanotags were employed to generate the detectable electronic signal.Biomolecular immobilization and construction of the sensing platform are usually crucial for the successful development of a high-efficiency detection system. Herein we report on a novel and label-free signal-amplified aptasensing for sensitive electrochemical detection of small molecules (adenosine triphosphate, ATP, used in this case) by coupling with target-induced hybridization chain reaction (HCR) and the assembly of electroactive silver nanotags. The system mainly consisted of two alternating hairpin probes, a partial-pairing trigger-aptamer duplex DNA and a capture probe immobilized on the electrode. Upon target ATP introduction, the analyte attacked the aptamer and released the trigger DNA, which was captured by capture DNA immobilized on the electrode to form a newly partial-pairing double-stranded DNA. Thereafter, the exposed domain at trigger DNA could be utilized as the initator strand to open the hairpin probes in sequence, and propagated a chain reaction of hybridization events between two alternating hairpins to form a long nicked double-helix. The electrochemical signal derived from the assembled silver nanotags on the nicked double-helix. Under optimal conditions, the electrochemical aptasensor could exhibit a high sensitivity and a low detection limit, and allowed the detection of ATP at a concentration as low as 0.03 pM. Our design showed a high selectivity for target ATP against its analogs because of the high-specificity ATP-aptamer reaction, and its applicable for monitoring ATP in the spiking serum samples. Improtantly, the distinct advantages of the developed aptasensor make it hold a great potential for the development of simple and robust sensing strategies for the detection of other small molecules by controlling the apatmer sequence.Schematic illustration of in situ amplified electrochemical aptasensor for sensitive monitoring of target ATP by coupling with target-induced hybridization chain reaction and the assembly of electroactive silver nanotags on capture DNA-modified gold electrode.
Co-reporter:Jian Shu, Zhenli Qiu, Junyang Zhuang, Mingdi Xu, and Dianping Tang
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 42) pp:23812
Publication Date(Web):October 9, 2015
DOI:10.1021/acsami.5b08742
An ultrasensitive photoelectrochemical (PEC) immunoassay protocol for quantitative detection of low-abundant proteins at a low potential was designed by utilizing porphyrin-sensitized titanium dioxide (TiO2) nanostructures. Experimental results demonstrated that the water-soluble 5,10,15,20-tetra(4-sulfophenyl)-21H,23H-porphyrin (TSPP) could be bound onto titanium dioxide via the sulfonic group. TSPP-sensitized TiO2 nanostructures exhibited better photoelectrochemical responses and stability in comparison with TiO2 nanoparticles alone under continuous illumination. Using carcinoembryonic antigen (CEA) as a model analyte, a typical PEC immunosensor by using TSPP-TiO2 as the affinity support of anti-CEA capture antibody (Ab1) to facilitate the improvement of photocurrent response was developed. Bioconjugates of secondary antibody and glucose oxidase with gold nanoparticles (Ab2/GOx-AuNPs) was introduced by an antigen–antibody immunoreaction. AuNP acted as a powerful scaffold to bind with bioactive molecules, while GOx catalyzed glucose to in situ generate hydrogen peroxide (H2O2). The generated H2O2 as a sacrificial electron donor could be oxidized by the photogenerated holes to assist the signal amplification at a low potential under light excitation, thus eliminating interference from other species coexisting in the samples. Under optimal conditions, the PEC immunosensor showed a good linear relationship ranging from 0.02 to 40 ng mL–1 with a low detection limit of 6 pg mL–1 CEA. The precision, reproducibility, and specificity were acceptable. In addition, the method accuracy was also evaluated for quantitatively monitoring human serum samples, giving results matching with the referenced CEA ELISA kit.Keywords: carcinoembryonic antigen; hybrid nanostructures; photocurrent; photoelectrochemical immunoassay; porphyrins; titanium dioxide nanostructures
Co-reporter:Junyang Zhuang, Wenqiang Lai, Mingdi Xu, Qian Zhou, and Dianping Tang
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 15) pp:8330
Publication Date(Web):April 2, 2015
DOI:10.1021/acsami.5b01923
A convenient and feasible photoelectrochemical (PEC) sensing platform based on gold nanoparticles-decorated g-C3N4 nanosheets (AuNP/g-C3N4) was designed for highly sensitive monitoring of T4 polynucleotide kinase (PNK) activity, using DNAzyme-mediated catalytic precipitation amplification. To realize our design, the AuNP/g-C3N4 nanohybrid was initially synthesized through in situ reduction of Au(III) on the g-C3N4 nanosheets, which was utilized for the immobilization of hairpin DNA1 (HP1) on the sensing interface. Thereafter, a target-induced isothermal amplification was automatically carried out on hairpin DNA2 (HP2) in the solution phase through PNK-catalyzed 5′-phosphorylation accompanying formation of numerous trigger DNA fragments, which could induce generation of hemin/G-quadruplex-based DNAzyme on hairpin DNA1. Subsequently, the DNAzyme could catalyze the 4-chloro-1-naphthol (4-CN) oxidation to produce an insoluble precipitation on the AuNP/g-C3N4 surface, thereby resulting in the local alternation of the photocurrent. Experimental results revealed that introduction of AuNP on the g-C3N4 could cause a ∼100% increase in the photocurrent because of surface plasmon resonance-enhanced light harvesting and separation of photogenerated e–/h+ pairs. Under the optimal conditions, the percentage of photocurrent decrement (ΔI/I0, relative to background signal) increased with the increasing PNK activity in a dynamic working range from 2 to 100 mU mL–1 with a low detection limit (LOD) of 1.0 mU mL–1. The inhibition effect of adenosine diphosphate also received a good performance in PNK inhibitor screening research, thereby providing a useful scheme for practical use in quantitative PNK activity assay for life science and biological research.Keywords: gold-decorated g-C3N4 nanosheets; isothermal amplification; photoelectrochemistry; surface plasmon resonance; T4 polynucleotide kinase;
Co-reporter:Youxiu Lin, Qian Zhou, Yuping Lin, Dianping Tang, Reinhard Niessner, and Dietmar Knopp
Analytical Chemistry 2015 Volume 87(Issue 16) pp:8531
Publication Date(Web):July 16, 2015
DOI:10.1021/acs.analchem.5b02253
A novel (invertase) enzymatic hydrolysate-triggered displacement reaction strategy with multifunctional silica beads, doped with horseradish peroxidase–thionine (HRP–Thi) conjugate, was developed for competitive-type electrochemical immunoassay of small molecular aflatoxin B1 (AFB1). The competitive-type displacement reaction was carried out on the basis of the affinity difference between enzymatic hydrolysate (glucose) and its analogue (dextran) for concanavalin A (Con A) binding sites. Initially, thionine–HRP conjugates were doped into nanometer-sized silica beads using the reverse micelle method. Then monoclonal anti-AFB1 antibody and Con A were covalently conjugated to the silica beads. The immunosensor was prepared by means of immobilizing the multifunctional silica beads on a dextran-modified sensing interface via the dextran–Con A binding reaction. Gold nanoparticles functionalized with AFB1–bovine serum albumin conjugate (AFB1–BSA) and invertase were utilized as the trace tag. Upon target AFB1 introduction, a competitive-type immunoreaction was implemented between the analyte and the labeled AFB1–BSA on the nanogold particles for the immobilized anti-AFB1 antibody on the electrode. The invertase followed by gold nanoparticles hydrolyzed sucrose into glucose and fructose. The produced glucose displaced the multifunctional silica beads from the electrode based on the classical dextran–Con A–glucose system, thus decreasing the catalytic efficiency of the immobilized HRP on the electrode relative to that of the H2O2–thionine system. Under optimal conditions, the detectable electrochemical signal increased with the increasing target AFB1 in a dynamic working range from 3.0 pg mL–1 to 20 ng mL–1 with a detection limit of 2.7 pg mL–1. The strong bioconjugation with two nanostructures also resulted in a good repeatability and interassay precision down to 9.3%. Finally, the methodology was further validated for analysis of naturally contaminated or spiked AFB1 peanut samples, giving results matched well with those from a commercialized AFB1 enzyme-linked immunosorbent assay kit. Importantly, the system provides a signal-on competitive-type immunosensing platform for ultrasensitive detection of small molecules.
Co-reporter:Zhuangqiang Gao, Dianyong Tang, Dianping Tang, Reinhard Niessner, and Dietmar Knopp
Analytical Chemistry 2015 Volume 87(Issue 19) pp:10153
Publication Date(Web):September 1, 2015
DOI:10.1021/acs.analchem.5b03008
Colorimetric assay platforms for dissolved hydrogen sulfide (H2S) have been developed for more than 100 years, but most still suffer from relatively low sensitivity. One promising route out of this predicament relies on the design of efficient signal amplification methods. Herein, we rationally designed an unprecedented H2S-induced deactivation of (gold core)@(ultrathin platinum shell) nanocatalysts (Au@TPt-NCs) as a highly efficient signal amplification method for ultrasensitive headspace-colorimetric assay of dissolved H2S. Upon target introduction, Au@TPt-NCs were deactivated to different degrees dependent on H2S levels, and the degrees could be indicated by using a Au@TPt-NCs-triggered catalytic system as a signal amplifier, thus paving a way for H2S sensing. The combination of experimental studies and density functional theory (DFT) studies revealed that the Au@TPt-NCs with only 2-monolayer equivalents of Pt (θPt = 2) were superior for H2S-induced nanocatalyst deactivation owing to their enhanced peroxidase-like catalytic activity and deactivation efficiency stemmed from the unique synergistic structural/electronic effects between Au nanocores and ultrathin Pt nanoshells. Importantly, our analytical results showed that the designed method was indeed highly sensitive for sensing H2S with a wide linear range of 10–100 nM, a slope of 0.013 in the regression equation, and a low detection limit of 7.5 nM. Also the selectivity, reproducibility, and precision were excellent. Furthermore, the method was validated for the analysis of H2S-spiked real samples, and the recovery in all cases was 91.6–106.7%. With the merits of high sensitivity and selectivity, simplification, low cost, and visual readout with the naked eye, the colorimetric method has the potential to be utilized as an effective detection kit for point-of-care testing.
Co-reporter:Junyang Zhuang, Dianyong Tang, Wenqiang Lai, Mingdi Xu, and Dianping Tang
Analytical Chemistry 2015 Volume 87(Issue 18) pp:9473
Publication Date(Web):August 20, 2015
DOI:10.1021/acs.analchem.5b02676
Photoelectrochemical (PEC) detection is an emerging and promising analytical tool. However, its actual application still faces some challenges like potential damage of biomolecules (caused by itself system) and intrinsic low-throughput detection. To solve the problems, herein we design a novel split-type photoelectrochemical immunoassay (STPIA) for ultrasensitive detection of prostate specific antigen (PSA). Initially, the immunoreaction was performed on a microplate using a secondary antibody/primer-circular DNA-labeled gold nanoparticle as the detection tag. Then, numerously repeated oligonucleotide sequences with many biotin moieties were in situ synthesized on the nanogold tag via RCA reaction. The formed biotin concatamers acted as a powerful scaffold to bind with avidin-alkaline phosphatase (ALP) conjugates and construct a nanoenzyme reactor. By this means, enzymatic hydrolysate (ascorbic acid) was generated to capture the photogenerated holes in the CdS quantum dot-sensitized TiO2 nanotube arrays, resulting in amplification of the photocurrent signal. To elaborate, the microplate-based immunoassay and the high-throughput detection system, a semiautomatic detection cell (installed with a three-electrode system), was employed. Under optimal conditions, the photocurrent increased with the increasing PSA concentration in a dynamic working range from 0.001 to 3 ng mL–1, with a low detection limit (LOD) of 0.32 pg mL–1. Meanwhile, the developed split-type photoelectrochemical immunoassay exhibited high specificity and acceptable accuracy for analysis of human serum specimens in comparison with referenced electrochemiluminescence immunoassay method. Importantly, the system was not only suitable for the sandwich-type immunoassay mode, but also utilized for the detection of small molecules (e.g., aflatoxin B1) with a competitive-type assay format.
Co-reporter:Youxiu Lin, Qian Zhou, Yuping Lin, Minghua Lu, Dianping Tang
Analytica Chimica Acta 2015 Volume 887() pp:67-74
Publication Date(Web):5 August 2015
DOI:10.1016/j.aca.2015.06.010
•We report on a new enzyme-free electrochemical immunoassay of marine toxin.•Mesoporous carbon was utilized as the substrate for assembly of palladium nanomaterial.•Mesoporous carbon-enriched palladium nanostructures were used as the peroxidase mimics.A new signal amplification strategy based on mesoporous carbon-enriched palladium nanostructure (MSC-PdNS) was designed for enzyme-free electrochemical immunoassay of brevetoxin B (BTB) in marine toxins. The assay was carried out on a BTB-bovine serum albumin-functionalized electrode by using monoclonal mouse anti-BTB-labeling MSC-PdNS as the signal-transduction tag. A competitive-type assay protocol was successfully introduced to develop a high-efficiency enzyme-free immunoassay accompanying the doped palladium nanostructure into MSC-PdNS toward reduction of H2O2. Under the optimal conditions, the catalytic current decreased with the increment of BTB concentration in the range from 0.01 to 10 ng mL−1 with a detection limit (LOD) of 5.0 pg mL−1 BTB at the 3sblank criterion. The selectivity and precision were acceptable. In addition, the methodology was further validated for assaying spiked seafood samples, and consistent results between the electrochemical immunoassay and the referenced enzyme immunoassay were obtained. Importantly, the enzyme-free electrochemical immunoassay provides a promising approach for rapid screening of marine toxin because of its simplicity, low cost, sensitivity, specificity and without the need of sample pretreatment.
Co-reporter:Wenqiang Lai, Junyang Zhuang, and Dianping Tang
Journal of Agricultural and Food Chemistry 2015 Volume 63(Issue 7) pp:1982-1989
Publication Date(Web):February 7, 2015
DOI:10.1021/acs.jafc.5b00425
A simple colorimetric immunoassay for quantitative monitoring of brevetoxin B on a functionalized magnetic bead by using glucose oxidase (GOx)/antibrevetoxin antibody-labeled gold nanoparticle as the signal transduction tag was developed. The assay was carried out on the basis of GOx-controlled sulfite-to-sulfate chemical conversion with a silver(I)–3,3′,5,5′-tetramethylbenzidine [Ag(I)–TMB] system. Initially, the sulfite was used as an inhibitor of Ag(I) to hinder the color development of TMB due to the formation of insoluble silver sulfite. Accompanying H2O2 generation with GOx-catalyzed glucose, the sulfite was converted into the sulfate, thus resulting in the colorless-to-blue change. Under the optimal conditions, the absorbance decreased with increasing brevetoxin B from 0.5 to 200 ng/kg with a detection limit of 0.1 ng/kg (ppt). The precision and specificity were acceptable. Furthermore, the methodology gave results matching well with the referenced brevetoxin ELISA kit for monitoring of spiked Musculista senhousia samples.
Co-reporter:Juan Tang
Microchimica Acta 2015 Volume 182( Issue 13-14) pp:2077-2089
Publication Date(Web):2015 October
DOI:10.1007/s00604-015-1567-8
Electrochemical immunodetection has attracted considerable attention due to its high sensitivity, low cost and simplicity. Large efforts have recently made in order to design ultrasensitive assays. Noble metal nanoparticles (NM-NPs) offer advantages such as high conductivity and large surface-to-volume ratio. NM-NPs therefore are excellent candidates for developing electrochemical platforms for immunodetection and as signal tags. The use of biofunctionalized NM-NPs often results in amplified recognition via stronger loading of signal tags, and also in enhanced signal. This review (with 87 references) gives an overview on the current state in the use of NM-NPs in Non-enzymatic electrochemical immunosensing. We discuss the application of NM-NPs as electrode matrices and as electroactive labels (either as a carrier or as electrocatalytic labels), and compare the materials (mainly nanoparticles of gold, platinum, or of bimetallic materials) in terms of performance (for example by increasing sensitivity via label amplification or via high densities of capture molecules). A conclusion covers current challenges and gives an outlook. Rather than being exhaustive, the review focuses on representative examples that illustrate novel concepts and promising applications. NM-NPs based immunosensing opens a series of concepts for basic research and offers new tools for determination of trace amounts of protein-related analytes in environment and clinical applications.
Co-reporter:Youxiu Lin, Qian zhou, Yuping Lin, Dianyong Tang, Guonan Chen, Dianping Tang
Biosensors and Bioelectronics 2015 Volume 74() pp:680-686
Publication Date(Web):15 December 2015
DOI:10.1016/j.bios.2015.07.029
•We designed a new non-conventional competitive-type electrochemical immunoassay.•Target-induced displacement reaction mode was adopted for AFB1 detection.•The assay could be carried out within five minute.•Thionine-decorated mesoporous carbon nanostructure was used as the signal-generation tag.A novel competitive-type immunosensing strategy based on target-induced displacement reaction with antibody-functionalized mesoporous carbon (MSC) nanoparticles was designed for sensitive and rapid electrochemical detection of aflatoxin B1 (AFB1, used as a model) on the Nafion-functionalized sensing interface. Electroactive thionine molecules were initially decorated to the mesoporous carbon, and polyclonal anti-AFB1 antibody was then covalently conjugated to the nanostructures. The immunosensor was simply prepared via the electrostatic interaction between negatively charged Nafion film and positively charged anti-AFB1 antibody accompanying the nanostructures. The electrochemical signal originated from the carried thionine to mesoporous carbon. Upon target AFB1 introduction, the analyte reacted with the labeled anti-AFB1 antibody on the MSC based on specific antigen–antibody reaction and induced the dissociation of thionine–MSN nanostructures from the sensing interface, thus decreasing the cathodic current of the carried thionine molecules. Under optimal conditions, the immunosensor exhibited good electrochemical responses for determination of target AFB1 at a concentration as low as 3.0 pg mL−1 (3.0 ppt). Importantly, the non-conventional sensing system provides a promising immunosensing strategy for rapid screening of small molecules because of its simplicity, low cost and sensitivity without the needs of sample separation and washing step.
Co-reporter:Jin Zhang, Ying Tang, Liumei Teng, Minghua Lu, Dianping Tang
Biosensors and Bioelectronics 2015 Volume 68() pp:232-238
Publication Date(Web):15 June 2015
DOI:10.1016/j.bios.2015.01.001
•We designed a low-cost and highly efficient DNA biosensor for Pb2+ detection.•Pb2+-specific DNAzyme-modified microplate was used as the detection cell.•A personal glucometer was utilized as the readout device.•The signal was amplified by the labeled invertase on gold nanoparticles.A simple and low-cost DNA sensing platform based on Pb2+-specific DNAzyme-modified microplate was successfully developed for highly sensitive monitoring of lead ion (Pb2+, one kind of toxic heavy metal ion) in the environmental samples coupling with a portable personal glucometer (PGM)-based detection mode. The detection cell was first prepared simply by means of immobilizing the DNAzyme on the streptavidin-modified microplate. Gold nanoparticle labeled with single-stranded DNA and invertase (Enz-AuNP-DNA) was utilized as the signal-transduction tag to produce PGM substrate (glucose). Upon addition of lead ion into the microplate, the substrate strand of the immobilized DNAzyme was catalytically cleaved by target Pb2+, and the newly generated single-strand DNA in the microplate could hybridize again with the single-stranded DNA on the Enz-AuNP-DNA. Accompanying with the Enz-AuNP-DNA, the carried invertase could convert sucrose into glucose. The as-produced glucose could be monitored by using a widely accessible PGM for in situ amplified digital readout. Based on Enz-AuNP-DNA amplification strategy, as low as 1.0 pM Pb2+ could be detected under the optimal conditions. Moreover, the methodology also showed good reproducibility and high selectivity toward target Pb2+ against other metal ions because of highly specific Pb2+-dependent DNAzyme, and was applicable for monitoring Pb2+ in the naturally contaminated sewage and spiked drinking water samples.
Co-reporter:Li Hou, Xiaoping Wu, Guonan Chen, Huanghao Yang, Minghua Lu, Dianping Tang
Biosensors and Bioelectronics 2015 Volume 68() pp:487-493
Publication Date(Web):15 June 2015
DOI:10.1016/j.bios.2015.01.043
•We devise a new impedimetric immunoassay for sensitive detection of low-abundance protein.•HCR-stimulated formation of DNAzyme concatamers on gold nanoparticle are used as molecular tags.•Using the enzymatic biocatalytic precipitation method can reach the aim of signal amplification.A novel signal-amplified impedimetric immunosensing strategy was successfully developed for ultrasensitive detection of low-abundance proteins (carcinoembryonic antigen, CEA, used as a model) based on hybridization chain reaction (HCR)-stimulated formation of DNAzyme concatamers on nanogold particle accompanying enzyme-triggered biocatalytic precipitation. The assay was carried out on capture antibody-modified electrode by using gold nanoparticle heavily functionalized with initiator strand and detection antibody as the signal-transduction tag with a sandwich-type immunosensing format. In the presence of target CEA, the formed immunocomplex underwent an unbiased strand-displacement reaction by the initiator strand on the gold nanoparticle between two auxiliary single-stranded DNA with the hemin aptamer. Upon hemin introduction, numerous DNAzyme molecules were formed on the concatamers and nanogold particle, which could catalyze 4-chloro-1-naphthol to produce an insoluble precipitation on the electrode, thereby resulting in the amplification of impedimetric signal. Under the optimal conditions, the immuno-HCR assay exhibited good impedimetric responses for the detection of target CEA in the working range from 1.0 pg mL−1 to 20 ng mL−1 with a detection limit of 0.42 pg mL−1. In addition, the immuno-HCR assay was validated by measuring six human serum specimens for target CEA, receiving a highly matched correction between the obtained results by the immuno-HCR assay and the commercialized ELC-based immunoassay method.
Co-reporter:Bingqian Liu, Jinfeng Chen, Qiaohua Wei, Bing Zhang, Lan Zhang, Dianping Tang
Biosensors and Bioelectronics 2015 Volume 69() pp:241-248
Publication Date(Web):15 July 2015
DOI:10.1016/j.bios.2015.02.040
•We designed a new signal-amplification for electrochemical monitoring of marine biotoxins.•Target-regulated DNA proximity hybridization reaction was used as the initiator.•The signal was induced through a three-way DNA junction.•The signal was amplified based on an isothermal cycling strategy.A new signal amplification strategy based on target-regulated DNA proximity hybridization (TRPH) reaction accompanying formation of three-way DNA junction was designed for electronic detection of Microcystin-LR (MC-LR used in this case), coupling with junction-induced isothermal cycling signal amplification. Initially, a sandwiched-type immunoreaction was carried out in a low-cost PCR tube between anti-MC-LR mAb1 antibody-labeled DNA1 (mAb1-DNA1) and anti-MC-LR mAb2-labeled DNA2 (mAb2-DNA2) in the presence of target to form a three-way DNA junction. Then, the junction could undergo an unbiased strand displacement reaction on an h-like DNA nanostructure-modified electrode (labeled with methylene blue redox tag on the short DNA strand), thereby resulting in the dissociation of methylene blue-labeled signal DNA from the electrode. The newly formed double-stranded DNA could be cleaved again by exonuclease III, and the released three-way DNA junction retriggered the strand-displacement reaction with h-like DNA nanostructures for junction recycling. During the strand-displacement reaction, numerous methylene blue-labeled DNA strands were far away from the electrode, thus decreasing the detectable electrochemical signal within the applied potentials. Under optimal conditions, the TRPH-based immunosensing system exhibited good electrochemical responses for detecting target MC-LR at a concentration as low as 1.0 ng kg−1 (1.0 ppt). Additionally, the precision, reproducibility, specificity and method accuracy were also investigated with acceptable results.
Co-reporter:Bing Zhang, Jinfeng Chen, Bingqian Liu, Dianping Tang
Biosensors and Bioelectronics 2015 Volume 69() pp:230-234
Publication Date(Web):15 July 2015
DOI:10.1016/j.bios.2015.02.041
•We designed an in-situ amplified electronic monitoring system for determination of lead ion.•The amplified system was carried out by target-induced Pb2+-dependent DNAzyme.•Hybridization chain reaction was used for DNA self-assembly.•The detectable signal was amplified by DNAzyme-catalyzed polymerization of aniline.Lead ion (Pb2+, a heavy metal ion existed every aspect of life) is one of the most important hazards for environment and human health. Herein we design an in-situ amplified electronic monitoring system for sensitive determination of Pb2+ on Pb2+-specific DNAzyme-modified sensing interface. The assay consists of target-triggered cleavage of Pb2+-specific DNAzyme, initiator strand-induced DNA hybridization chain reaction, formation of hemin/G-quadruplex -based DNAzyme and its automatically catalyzed polymerization of aniline monomer along the double-stranded DNA. Experimental results indicated that the catalytic currents of the as-produced polyaniline were linearly dependent on target Pb2+ concentrations from 0.05 to 50 nM with a detection limit (LOD) of 32 pM. Such a synergistic effect of hybridization chain reaction with DNAzyme-catalyzed polymerization provided a universal platform for sensitive screening of target Pb2+, thereby holding great promise for application in practice.
Co-reporter:Zhuangqiang Gao, Mingdi Xu, Minghua Lu, Guonan Chen, Dianping Tang
Biosensors and Bioelectronics 2015 70() pp: 194-201
Publication Date(Web):
DOI:10.1016/j.bios.2015.03.039
Co-reporter:Bing Zhang, Bingqian Liu, Guonan Chen, Dianping Tang
Biosensors and Bioelectronics 2015 Volume 64() pp:6-12
Publication Date(Web):15 February 2015
DOI:10.1016/j.bios.2014.08.024
•We introduced a new electrochemical immunoassay for detection of low-abundance protein.•Redox and catalysis ‘all-in-one’ infinite coordination polymer was used as molecular tag.•The assay was carried out on polyamidoamine dendrimer-based sensing platform.Prostate-specific antigen (PSA), as a glycoprotein enzyme encoded in humans by the KLK3 gene, is one of the most important biomarkers for the diagnosis and prognosis of prostate cancer. Herein, a new electrochemical immunosensor for sensitive determination of PSA was designed by using redox and catalysis ‘all-in-one’ infinite coordination polymer (PtNP@ICP) as signal tag on the polyamidoamine dendrimers modified electrode interface. To construct such ‘all-in-one’ PtNP@ICP nanostructures, the coordination polymerization was fully carried between metal ions and polydentate bridging ligands, and the PtNP was encapsulated into the ICP in the process of polymerization. The prepared PtNP@ICP nanocatalyst was characterized by transmission electron microscope (TEM), energy dispersive X-ray spectrometry (EDX), ultraviolet and visible (UV–vis) spectrophotometry and Fourier transform infrared spectroscope (FTIR). And the synthesized PtNP@ICP was utilized as signal tag for the label of PSA. With a sandwich-type immunoassay format, the conjugated signal tag on the transducer increased with the increasing PSA concentration in the sample thus enhancing the signal of the electrochemical immunosensor due to the catalytic reduction toward H2O2 of the enveloped PtNP. Under optimal conditions, the current was proportional to the logarithm of PSA concentration ranging from 0.001 to 60 ng/mL. The detection limit (LOD) was 0.3 pg/mL at 3sB. The immunosensor displayed an acceptable reproducibility, stability and selectivity. In addition, the methodology was evaluated with human serum specimens receiving good correlation with results from commercialized enzyme-linked immunosorbent assay (ELISA) method.
Co-reporter:Zhuangqiang Gao, Dianping Tang, Mingdi Xu, Guonan Chen and Huanghao Yang
Chemical Communications 2014 vol. 50(Issue 47) pp:6256-6258
Publication Date(Web):23 Apr 2014
DOI:10.1039/C4CC01511H
A novel homogeneous immunoassay method is developed for sensitive monitoring of small molecular biotoxin by using a portable personal glucose meter (PGM) based on the target-responsive release of cargo (glucose) from a polystyrene microsphere-gated magnetic mesoporous nanocontainer.
Co-reporter:Junyang Zhuang, Wenqiang Lai, Guonan Chen and Dianping Tang
Chemical Communications 2014 vol. 50(Issue 22) pp:2935-2938
Publication Date(Web):27 Jan 2014
DOI:10.1039/C3CC49873E
A novel DNA nanomachine based on the linear rolling circle amplification strategy was designed for sensitive screening of microRNA (miRNA) at an ultralow concentration coupling catalytic hairpin assembly (CHA) with DNAzyme formation.
Co-reporter:Bingqian Liu, Bing Zhang, Guonan Chen and Dianping Tang
Chemical Communications 2014 vol. 50(Issue 15) pp:1900-1902
Publication Date(Web):09 Dec 2013
DOI:10.1039/C3CC49005J
An omega (Ω)-like DNA nanostructure was for the first time utilized for homogenous electrochemical monitoring of small molecules (ATP used in this case) based on target-induced formation of DNAzyme–aptamer conjugates without the need for sample separation and washing.
Co-reporter:Li Hou, Chunling Zhu, Xiaoping Wu, Guonan Chen and Dianping Tang
Chemical Communications 2014 vol. 50(Issue 12) pp:1441-1443
Publication Date(Web):25 Nov 2013
DOI:10.1039/C3CC48453J
A novel sensing platform for monitoring small molecules without the need for sample separation and washing is developed by using a commercialized personal glucose meter based on bioresponsive controlled release of glucose from aptamer-gated mesoporous silica nanocontainers.
Co-reporter:Zhuangqiang Gao, Kaichao Deng, Xu-Dong Wang, Manuel Miró, and Dianping Tang
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 20) pp:18243
Publication Date(Web):September 22, 2014
DOI:10.1021/am505342r
Nanostructure-based visual assay has been developed for determination of enzymatic activity, but most involve in poor visible color resolution and are not suitable for routine utilization. Herein, we designed a high-resolution colorimetric protocol based on gold/silver core/shell nanorod for visual readout of alkaline phosphatase (ALP) activity by using bare-eyes. The method relied on enzymatic reaction-assisted silver deposition on gold nanorod to generate significant color change, which was strongly dependent on ALP activity. Upon target ALP introduction into the substrate, the ascorbic acid 2-phosphate was hydrolyzed to form ascorbic acid, and then, the generated ascorbic acid reduced silver ion to metal silver and coated on the gold nanorod, thereby resulting in the blue shift of longitudinal localized surface plasmon resonance peak of gold nanorod accompanying a perceptible color change from red to orange to yellow to green to cyan to blue and to violet. Under optimal conditions, the designed method exhibited the wide linear range 5–100 mU mL–1 ALP with a detection limit of 3.3 mU mL–1. Moreover, it could be used for the semiquantitative detection of ALP from 20 to 500 mU mL–1 by using the bare-eyes. The coefficients of variation for intra- and interassay were below 3.5% and 6.2%, respectively. Finally, this method was validated for the analysis of real-life serum samples, giving results matched well with those from the 4-nitrophenyl phosphate disodium salt hexahydrate (pNPP)-based standard method. In addition, the system could even be utilized in the enzyme-linked immunosorbent assay (ELISA) to detect IgG at picomol concentration. With the merits of simplification, low cost, user-friendliness, and sensitive readout, the gold nanorod-based colorimetric assay has the potential to be utilized by the public and opens a new horizon for bioassays.Keywords: alkaline phosphatase; bare-eyes; gold nanorod; high-resolution colorimetric assay; localized surface plasmon resonance
Co-reporter:Wenqiang Lai, Dianping Tang, Junyang Zhuang, Guonan Chen, and Huanghao Yang
Analytical Chemistry 2014 Volume 86(Issue 10) pp:5061
Publication Date(Web):April 30, 2014
DOI:10.1021/ac500738a
This work reports on a simple and feasible colorimetric immunoassay with signal amplification for sensitive determination of prostate-specific antigen (PSA, used as a model) at an ultralow concentration by using a new enzyme-chromogenic substrate system. We discovered that glucose oxidase (GOx), the enzyme broadly used in enzyme-linked immunosorbent assay (ELISA), has the ability to stimulate in situ formation of squaric acid (SQA)-iron(III) chelate. GOx-catalyzed oxidization of glucose leads to the formation of gluconic acid and hydrogen peroxide (H2O2). The latter can catalytically oxidize iron(II) to iron(III), which can rapidly (<1 min) coordinate with the SQA. Formation of the iron-squarate complex causes the color of the solution to change from bluish purple to bluish red accompanying the increasing absorbance with the increment of iron(III) concentration. On the basis of the SQA-iron(III) system, a new immunoassay protocol with GOx-labeled anti-PSA detection antibody can be designed for the detection of target PSA on capture antibody-functionalized magnetic immunosensing probe, monitored by recording the color or absorbance (λ = 468 nm) of the generated SQA-iron(III) chelate. The absorbance intensity shows to be dependent on the concentration of target PSA. A linear dependence between the absorbance and target PSA concentration is obtained under optimal conditions in the range from 1.0 pg mL–1 to 30 ng mL–1 with a detection limit (LOD) of 0.5 pg mL–1 (0.5 ppt) estimated at the 3Sblank level. The sensitivity displays to be 3–5 orders of magnitude better than those of most commercialized human PSA ELISA kits. In addition, the developed colorimetric immunoassay was validated by assaying 12 human serum samples, receiving in good accordance with those obtained by the commercialized PSA ELISA kit. Importantly, the SQA-based immunosensing system can be further extended for the detection of other low-abundance proteins or biomarkers by controlling the target antibody.
Co-reporter:Bingqian Liu, Bing Zhang, Guonan Chen, Huanghao Yang, and Dianping Tang
Analytical Chemistry 2014 Volume 86(Issue 15) pp:7773
Publication Date(Web):July 1, 2014
DOI:10.1021/ac501690v
A new signal amplification strategy based on target-induced proximity ligation assay accompanying three-way junction-based rolling chain amplification was designed for ultrasensitive detection of concanavalin A (Con A) by coupling with a sequential injection mode. To construct such a proximity ligation assay system, two types of magnetic sensing probes including glucosamine/DNA1-conjugated magnetic bead (GA-MB-DNA1) and glucosamine/DNA2-labeled magnetic bead (GA-MB-DNA2) were first synthesized and prepared through a typical carbodiimide coupling. In the presence of target Con A, GA-MB-DNA1 and GA-MB-DNA2 were ligated together based on the interaction between Con A and the conjugated glucosamine on the MB, thereby resulting in the formation of a three-way DNA junction because of partial base pairing on the DNA1/DNA2. With the aid of ligase and polymerase, the formed three-way DNA junction could be used as the primer to produce numerous repeated oligonucleotide sequences through rolling circle amplification (RCA) reaction. The formed long oligonucleotide strand could cause the intercalation of numerous positively charged methylene blue molecules with a negatively charged DNA backbone. During the electrochemical measurement, each of the intercalated indicators could produce an electrochemical signal within the applied potentials, resulting in the amplification of detectable electronic signal. By monitoring the change in the signal, we could indirectly determine the concentration of target Con A in the sample. Under the optimal conditions, the developed sensing platform exhibited high sensitivity for detection of Con A with a wide dynamic range of 1.96 pM to 98 nM and a low limit of detection (LOD) of 1.5 pM at the 3sB level. Intra-assay and interassay coefficients of variation were less than 8.9% and 9.7%, respectively. In addition, the methodology was validated by assaying Con A spiked samples including newborn cattle serum and peanuts, and the recovery in all cases was 88.8–134.7%.
Co-reporter:Junyang Zhuang, Dianping Tang, Wenqiang Lai, Guonan Chen, and Huanghao Yang
Analytical Chemistry 2014 Volume 86(Issue 16) pp:8400
Publication Date(Web):August 1, 2014
DOI:10.1021/ac501986k
This work designs a novel programmable hairpin probe (PHP) for the immobilization-free electrochemical detection of nucleic acid by coupling polymerase/nicking-induced isothermal signal amplification strategy with a biphasic reaction mode for the first time. The designed PHP (including a target-recognition region, a template sequence for enzymatic reaction and an inactivated anti-streptavidin aptamer) could program multiple isothermal reactions in the solution phase accompanying in situ amplified detectable signal at the electrode surface by the labeled ferrocene tag on the PHP. Upon addition of target analyte into the detection solution, target DNA initially hybridized with the recognition region on the PHP. Replication-induced strand-displacement generated an activated anti-streptavidin aptamer with the assistance of polymerase. Then, the polymerase/nicking enzymes could cleave and polymerize repeatedly the replication product, thus resulting in the formation of numerous template-complementary DNA initiator strands. The released initiator strands could retrigger the programmable hairpin probe to produce a large number of activated anti-streptavidin aptamers, which could be captured by the immobilized streptavidin on the electrode, thus activating the electrical contact between the labeled ferrocene and the electrode. Going after the aptamers, the carried ferrocene could produce the in situ amplified electronic signal within the applied potentials. Under optimal conditions, the electrochemical signal increased with the increasing target DNA concentration in the dynamic range from 5 fM to 10 pM with a detection limit (LOD) of 2.56 fM at the 3sblank criterion. Importantly, the methodology with high specificity was also validated and evaluated by assaying 6 target DNA-spiked human serum and calf thymus DNA samples, and the recoveries were 95–110%. Further work for the programmable hairpin probe could be even utilized in a real world sample to detect miRNA-21 at femtomol level.
Co-reporter:Li Hou, Yun Tang, Mingdi Xu, Zhuangqiang Gao, and Dianping Tang
Analytical Chemistry 2014 Volume 86(Issue 16) pp:8352
Publication Date(Web):August 4, 2014
DOI:10.1021/ac501898t
A new impedimetric immunoassay protocol based on enzyme-triggered formation of tyramine-enzyme repeats on gold nanoparticle (AuNP) was designed for highly sensitive detection of carcinoembryonic antigen (CEA, as a model) by virtue of utilizing enzymatic biocatalytic precipitation toward 4-chloro-1-naphthol (4-CN) on anti-CEA antibody (Ab1)-modified immunosensor. Initially, AuNP was functionalized with horseradish peroxidase and detection antibody (HRP-AuNP-Ab2), and then HRP–tyramine conjugate was utilized for the formation of tyramine–HRP repeats through the triggering of the immobilized HRP on the AuNP with the aid of H2O2. In the presence of target CEA, the carried HRP–tyramine repeats accompanying the sandwiched immunocomplex catalyzed the 4-CN oxidation to produce an insoluble precipitation on the immunosensor, thus causing a local alteration of the conductivity. Three signal-transduction tags including HRP-Ab2, HRP-AuNP-Ab2, and HRP-AuNP-Ab2 with HRP–tyramine repeats were employed for target CEA evaluation, and improved analytical properties were achieved by HRP-AuNP-Ab2 with HRP–tyramine repeats. Using the unique signal-transduction tag, the analytical performance of the impedimetric immunoassay was studied in detail. Under the optimal conditions, the impedimetric immunosensor displayed a wide dynamic working range of between 0.5 pg mL–1 and 40 ng mL–1 with a detection limit (LOD) of 0.38 pg mL–1 relative to target CEA. The coefficients of variation (CVs) were ≤9.3% and 13.3% for the intra-assay and interassay, respectively. The levels of CEA in eight clinical serum specimens were measured by using the developed impedimetric immunosensor. The obtained results correlated well with those from the electrochemiluminescent (ECL)-based immunoassay with a correlation coefficient of 0.998.
Co-reporter:Dianping Tang, Youxiu Lin, Qian Zhou, Yuping Lin, Peiwu Li, Reinhard Niessner, and Dietmar Knopp
Analytical Chemistry 2014 Volume 86(Issue 22) pp:11451
Publication Date(Web):October 20, 2014
DOI:10.1021/ac503616d
Aflatoxins are highly toxic secondary metabolites produced by a number of different fungi and present in a wide range of food and feed commodities. Herein, we designed a simple and low-cost immunosensing platform for highly sensitive detection of mycotoxins (aflatoxin B1, AFB1, used as a model) on polyethylenimine (PEI)-coated mesoporous silica nanocontainers (PEI-MSN). The assay was carried out by using a portable personal glucometer (PGM) as the readout based on a competitive displacement reaction mode between target AFB1 and its pseudo-hapten (PEI-MSN) for monoclonal anti-AFB1 antibody (mAb). To construct such an assay protocol, two nanostructures including mAb-labeled gold nanoparticle (mAb-AuNP) and PEI-MSN were initially synthesized, and then numerous glucose molecules were gated into the pores based on the interaction between negatively charged mAb-AuNP and positively charged PEI-MSN. In the presence of target AFB1, a competitive-type displacement reaction was implemented between mAb-AuNP and PEI-MSN by target AFB1 through the specific antigen–antibody reaction. Accompanying the reaction, target AFB1 could displace the mAb-AuNP from the surface of PEI-MSN, resulting in the release of the loading glucose from the pores due to the gate opened. The released glucose molecules could be quantitatively determined by using a portable PGM. Under optimal conditions, the PGM signal increased with the increment of AFB1 concentration in the range from 0.01 to 15 μg/kg (ppb) with a detection limit (LOD) of 5 ng/kg (5 ppt) at the 3sblank criterion. The selectivity and precision were acceptable. Importantly, the methodology was further validated for assaying naturally contaminated or spiked blank peanut samples, and consistent results between the PGM-based immunoassay and the referenced enzyme-linked immunosorbent assay (ELISA) were obtained. Therefore, the developed immunoassay provides a promising approach for rapid screening of organic pollutants because it is simple, low-cost, sensitive, specific, and without the need of multiple separation and washing steps.
Co-reporter:Bing Zhang, Yu He, Bingqian Liu, Dianping Tang
Analytica Chimica Acta 2014 Volume 851() pp:49-56
Publication Date(Web):3 December 2014
DOI:10.1016/j.aca.2014.08.026
•We report a new oxidase mimetic system for highly efficient electrochemical immunoassay.•NiCoBP-doped carbon nanotube hybrids were used as the nanocatalysts.•NiCoBP-doped carbon nanotube hybrids were used as the mimic oxidase.NiCoBP-doped multi-walled carbon nanotube (NiCoBP–MWCNT) was first synthesized by using induced electroless-plating method and functionalized with the biomolecules for highly efficient electrochemical immunoassay of prostate-specific antigen (PSA, used as a model analyte). We discovered that the as-synthesized NiCoBP–MWCNT had the ability to catalyze the glucose oxidization with a stable and well-defined redox peak. The catalytic current increased with the increment of the immobilized NiCoBP–MWCNT on the electrode. Transmission electron microscope (TEM) and energy dispersive X-ray spectrometry (EDX) were employed to characterize the as-prepared NiCoBP–MWCNT. Using the NiCoBP–MWCNT-conjugated anti-PSA antibody as the signal-transduction tag, a new enzyme-free electrochemical immunoassay protocol could be designed for the detection of target PSA on the capture antibody-functionalized immunosensing interface. Experimental results revealed that the designed immunoassay system could exhibit good electrochemical responses toward target PSA, and allowed the detection of PSA at a concentration as low as 0.035 ng mL−1. More importantly, the NiCoBP-MWCNT-based oxidase mimetic system could be further extended for the monitoring of other low-abundance proteins or disease-related biomarkers by tuning the target antibody.
Co-reporter:Junyang Zhuang, Yu He, Guonan Chen, Dianping Tang
Electrochemistry Communications 2014 Volume 47() pp:25-28
Publication Date(Web):October 2014
DOI:10.1016/j.elecom.2014.07.021
•A universal electrochemical aptasensor fabrication strategy was developed.•Binding-induced internal-displacement of inverted aptamer beacon•Signal-on electrochemical aptasensor•Sensitive detection of thrombin•The aptasensor is regenerable and reusable.In this paper, we reported a novel electrochemical aptasensor based on an inverted aptamer beacon (IAB). The IAB architecture with a hairpin structure consisted of an aptamer arm and a ferrocene (Fc)-labeling signal arm, and was inverted on the electrode through a thiol-linker on the middle site of its loop. The inverted immobilization strategy prevented the end-labeling of ferrocene tag from approaching the electrode, thus resulting in a weak electrochemical signal. In the presence of thrombin, binding of target with the aptamer arm displaced the signaling arm, producing a flexible single-stranded element, i.e. internal-displacement which allowed Fc tag to collide with the electrode, thereby producing a relatively strong electrochemical signal. By monitoring the increased signal, thrombin could be readily detected in the signal-on mode with a detection limit (LOD) of 0.21 nM. Inspiringly, the IAB-based strategy required no auxiliary strands and did not depend on structure-switching of specific aptamer/target couple, thus presenting as a generalized method for fabrication of other electrochemical aptasensors.
Co-reporter:Wenqiang Lai, Junyang Zhuang, Xiaohua Que, Libing Fu and Dianping Tang
Biomaterials Science 2014 vol. 2(Issue 8) pp:1073-1079
Publication Date(Web):10 Mar 2014
DOI:10.1039/C3BM60284B
A new electrochemical immunosensor was designed for the determination of carcinoembryonic antigen (CEA) with sensitivity enhanced by using nanogold–poly(o-phenylenediamine)–manganese dioxide organic–inorganic hybrid nanostructures (GNPM) as nanotags and peroxidase mimics. Initially, mesoporous poly(o-phenylenediamine)–manganese dioxide (PPD–MnO2) hollow microspheres were synthesized by an inorganic/organic interfacial polymerization technique. Then gold nanoparticles were assembled onto the surface of PPD–MnO2, which were used for the labelling of the anti-CEA detection antibody (pAb2). The prepared GNPM nanotags were characterized using transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), UV-vis absorption spectroscopy, N2 adsorption–desorption isotherm measurements and Fourier transform infrared spectroscopy (FTIR). The assay was carried out with a sandwich-type immunoassay format in pH 5.5 acetic acid-buffered saline solution containing 2.5 mmol L−1 H2O2. Experimental results indicated that the electrochemical immunosensor exhibited a wide dynamic range from 0.01 to 80 ng mL−1 towards the target CEA with a detection limit (LOD) of 6.0 pg mL−1. The immunosensor also displayed a good stability and acceptable reproducibility and selectivity. In addition, the methodology was evaluated by assaying 10 clinical serum samples, providing a good relationship between the electrochemical immunosensor and the commercialized electrochemiluminescent (ECL) method for determination of CEA.
Co-reporter:Juan Tang, Minghua Lu and Dianping Tang
Analyst 2014 vol. 139(Issue 12) pp:2998-3001
Publication Date(Web):14 Apr 2014
DOI:10.1039/C4AN00523F
A target-initiated proximity ligation assay (PLA) protocol accompanying DNAzyme formation was for the first time designed for ultrasensitive impedimetric monitoring of heavy metal ions (silver ions were used in this case) by coupling with enzymatic biocatalytic precipitation.
Co-reporter:Qunfang Li, Fangming Lou and Dianping Tang
Analytical Methods 2014 vol. 6(Issue 10) pp:3442-3448
Publication Date(Web):03 Mar 2014
DOI:10.1039/C4AY00086B
A novel signal-amplified strategy for sensitive electrochemical immunoassay of cancer marker (human tissue polypeptide antigen, TPA, used in this case) is developed by using Prussian blue nanoparticles-doped nanogold microsphere (AuPB) as the promoter. To construct such an immunoassay, the AuPB was initially synthesized by using the reverse micelle method, and the as-synthesized AuPB was then heavily functionalized with horseradish peroxidase (HRP) and anti-TPA antibody. Based on a specific sandwich-type immunoassay format, target TPA was monitored on anti-TPA-functionalized glassy carbon electrode by using the biofunctional AuPB as the signal tag. Compared with conventional nanogold labeling, the as-prepared AuPB possessed good redox activity, which could be employed as an electron mediator for improvement of catalytic efficiency of the labeled HRP. Under optimal conditions, the electrochemical immunoassay presents good electrochemical responses toward target TPA, and allowed the detection of TPA at a concentration as low as 5 pg mL−1. The precision, reproducibility, specificity and stability of the electrochemical immunoassay are acceptable. In addition, the methodology is validated for the analysis of 8 clinic human serum specimens and 8 spiked serum samples, receiving in good accordance with the results obtained from the referenced enzyme-linked immunosorbent assay (ELISA) method.
Co-reporter:Dr. Qunfang Li; Dianping Tang;Dr. Fangming Lou; Ximei Yang; Guonan Chen
ChemElectroChem 2014 Volume 1( Issue 2) pp:441-447
Publication Date(Web):
DOI:10.1002/celc.201300039
Abstract
A sensitive and feasible multiplexed immunoassay protocol for simultaneous electrochemical determination of carcinoembryonic antigen (CEA) and alpha-fetoprotein (AFP) was developed using multifunctionalized graphene nanotags on a cyclodextrin-modified immunosensor. The sensor was fabricated via the guest–host chemistry between the immobilized cyclodextrin and anti-CEA/anti-AFP antibodies. Two nanotags including cyclodextrin-thionine-graphene and cyclodextrin-ferrocene-graphene nanostructures were synthesized based on a wet chemistry method. The synthesized nanotags were employed for the labelling of horseradish peroxidase (HRP)–anti-AFP and HRP–anti-CEA conjugates, respectively. With a sandwich-type assay format, the signal was monitored through the labelling of HRP toward catalytic reduction of H2O2 at various peak potentials in the presence of thionine and ferrocene, respectively. Under optimal conditions, the multiplexed immunoassay enabled the simultaneous determination of CEA and AFP with wide working ranges of 0.001–60 ng mL−1 for AFP and 0.003–40 ng mL−1 for CEA. The detection limits were 0.5 pg ml−1 for AFP and 0.8 pg ml−1 for CEA (at 3 sB). No obvious nonspecific adsorption and cross-talk were observed during a series of analyses to detect target analytes. Intra- and inter-assay coefficients of variation (CV) were below 9.5 %. Importantly, the methodology was also evaluated for the analysis of AFP and CEA in the clinical human serum specimens, receiving a good relationship between the developed immunoassay and a commercialized electrochemiluminescence enzyme-linked immunoassay.
Co-reporter:Jinfeng Chen, Juan Tang, Jun Zhou, Lan Zhang, Guonan Chen, Dianping Tang
Analytica Chimica Acta 2014 810() pp: 10-16
Publication Date(Web):31 January 2014
DOI:10.1016/j.aca.2013.12.010
•We report a new electrochemical sensing protocol for the detection of mercury ion.•Gold amalgamation on DNA-based sensing platform was used as nanocatalyst.•The signal was amplified by cycling signal amplification strategy.Heavy metal ion pollution poses severe risks in human health and environmental pollutant, because of the likelihood of bioaccumulation and toxicity. Driven by the requirement to monitor trace-level mercury ion (Hg2+), herein we construct a new DNA-based sensor for sensitive electrochemical monitoring of Hg2+ by coupling target-induced formation of gold amalgamation on DNA-based sensing platform with gold amalgamation-catalyzed cycling signal amplification strategy. The sensor was simply prepared by covalent conjugation of aminated poly-T(25) oligonucleotide onto the glassy carbon electrode by typical carbodiimide coupling. Upon introduction of target analyte, Hg2+ ion was intercalated into the DNA polyion complex membrane based on T–Hg2+–T coordination chemistry. The chelated Hg2+ ion could induce the formation of gold amalgamation, which could catalyze the p-nitrophenol with the aid of NaBH4 and Ru(NH3)63+ for cycling signal amplification. Experimental results indicated that the electronic signal of our system increased with the increasing Hg2+ level in the sample, and has a detection limit of 0.02 nM with a dynamic range of up to 1000 nM Hg2+. The strategy afforded exquisite selectivity for Hg2+ against other environmentally related metal ions. In addition, the methodology was evaluated for the analysis of Hg2+ in spiked tap-water samples, and the recovery was 87.9–113.8%.
Co-reporter:Xiaohua Que, Dianyong Tang, Biyun Xia, Minghua Lu, Dianping Tang
Analytica Chimica Acta 2014 830() pp: 42-48
Publication Date(Web):9 June 2014
DOI:10.1016/j.aca.2014.04.051
•We report a new competitive-type immunoassay protocol for the detection of antibiotic residue.•Gold nanoparticles are used as nanotags and nanocatalysts for signal amplification.•The assay is implemented by catalytic reduction of gold nanocatalysts toward 4-nitropheneol.A new competitive-type immunosensing system based on gold nanoparticles toward catalytic reduction of 4-nitrophenol (4-NP) was developed for sensitive monitoring of antibiotic residue (chloramphenicol, CAP, used in this case) by using ultraviolet–visible (UV–vis) spectrometry. Gold nanoparticle (AuNP) with 16 nm in diameter was initially synthesized and functionalized with CAP–bovine serum albumin (CAP–BSA) conjugate, which were used as the competitor on monoclonal anti-CAP antibody-coated polystyrene microtiter plate (MTP). In the presence of target CAP, the labeled CAP–BSA on the AuNP competed with target CAP for the immobilized antibody on the MTP. The conjugated amount of CAP–BSA–AuNP on the MTP decreased with the increase of target CAP in the sample. Upon addition of 4-NP and NaBH4 into the MTP, the carried AuNP could catalytically reduce 4-NP to 4-aminophenol (4-AP), and the as-produced 4-AP could be monitored by using UV–vis absorption spectroscopy. Experimental results indicated that the absorbance at 403 nm increased with the increment of target CAP concentration in the sample, and exhibited a dynamic range from 0.1 to 100 ng mL−1 with a detection limit (LOD) of 0.03 ng mL−1 at the 3sblank level. Intra- and inter-assay coefficients of variation were lower than 5.5% and 8.0%, respectively. In addition, the methodology was evaluated for CAP spiked honey and milk samples, respectively. The recovery was 92–112%.
Co-reporter:Bingqian Liu, Bing Zhang, Guonan Chen, Huanghao Yang, Dianping Tang
Biosensors and Bioelectronics 2014 Volume 53() pp:390-398
Publication Date(Web):15 March 2014
DOI:10.1016/j.bios.2013.10.022
•A new aptasensor is designed for sensitive electronic monitoring of ATP.•CdS-DNA concatamers were used for the amplification of electronic signal.•Programmable capillary was utilized for the design of the aptasensor.A new flow-through electrochemical aptasensor was designed for ultrasensitive monitoring of adenosine triphosphate (ATP) by coupling microvalve-programmable capillary column with CdS-functionalized DNA concatamer for signal amplification. Initially, a layer of primary DNA-conjugated polyacrylamide hydrogel was covalently linked onto the internal surface of capillary column, and then an automated sequenctial injection format with a syringe pump was employed for development of the programmable capillary-based aptasensor. In the presence of target DNA aptamer, the immobilized primary DNA hybridized with partial bases of the aptamer. The excess aptamer fregment could trigger the formation of DNA concatamer between auxiliary DNA1 and CdS-labeled auxiliary DNA2. Upon target ATP introduction, a specific ATP-aptamer reaction was excuated, thereby resulting in the release of CdS-functionalized DNA concatamer from the capillary. Subsenquent anodic stripping voltammetric detection of cadmium released under acidic conditions from the released CdS nanoparticles could be conducted in a homemade detection cell. Under optimal conditions, the dynamic concentration range spanned from 0.1 pM to 10 nM ATP with a detection limit of 0.06 pM ATP. The electrochemical aptasensor showed good reproducibility, selectivity, and stability. In addition, the methodology was evaluated for the analysis of ATP spiked serum samples, and the recoveries was 81–140%.
Co-reporter:Bing Zhang, Bingqian Liu, Guonan Chen, Dianping Tang
Biosensors and Bioelectronics 2014 Volume 53() pp:465-471
Publication Date(Web):15 March 2014
DOI:10.1016/j.bios.2013.10.027
•We introduced a new homogeneous immunoassay for detection of low-abundance protein.•Competitive-type displacement reaction was utilized during the measurement.•The assay was carried out on an electrostatic reaction-based sensing platform.Prostate-specific antigen (PSA), one of the indications of possible prostate malignancy, is used as a biomarker for the diagnosis and prognosis of prostate cancer. Herein, we develop a new homogeneous potentiometric immunoassay for sensitive detection of low-concentration PSA without the need of sample separation and washing step. Two nanostructures including positively charged polyethyleneimine-poly(styrene-co-acrylic acid) (PEI-PSAA) nanospheres and negatively charged gold nanoparticles conjugated with anti-PSA antibody (Ab-AuNP) were first synthesized by using mulsifier-free emulsion copolymerization and wet chemistry method, respectively. Thereafter, the as-prepared PEI-PSAA was used as a pseudo hapten for the construction of immunosensing probe based on an electrostatic interaction between PEI-PSAA and Ab-AuNP. Upon target introduction, the added PSA competed with PEI-PASS for Ab-AuNP based on a specific antigen–antibody interaction, and displaced Ab-AuNP from PEI-PASS. The dissociated PEI-PASS was captured through the negatively charged Nafion- modified electrode, thereby resulting in the change of membrane potential. The fabrication process was characterized by using high-resolution transmission electron microscope (HRTEM), scanning electron microscope with energy-dispersive X-ray spectroscopy (SEM-EDX), surface plasmon resonance (SPR) and dynamic laser scattering (DLS) technique. Under optimal conditions, the output signal was indirectly proportional to the concentration of target PSA in the sample and exhibited a dynamic range from 0.1 to 50 ng/mL with a detection limit (LOD) of 0.04 ng/mL. Intra- and inter-assay coefficients of variation (CVs) were 6.8 and 7.5%, respectively. In addition, the methodology was evaluated for analysis of 12 clinical serum samples and showed good accordance between the results obtained by the developed immunosensing protocol and a commercialized enzyme-linked immunosorbent assay (ELISA) method.
Co-reporter:Dianping Tang, Bing Zhang, Bingqian Liu, Guonan Chen, Minghua Lu
Biosensors and Bioelectronics 2014 Volume 55() pp:255-258
Publication Date(Web):15 May 2014
DOI:10.1016/j.bios.2013.12.022
•We introduce a new digital multimeter-based immunoassay for detection of biomarker.•Digital multimeter was used for signal readout.•Enzyme immunoassay was utilized for signal amplification.A new digital multimeter (DMM)-based immunosensing system was designed for quantitative monitoring of biomarker (prostate-specific antigen, PSA used in this case) by coupling with an external capacitor and an enzymatic catalytic reaction. The system consisted of a salt bridge-linked reaction cell and a capacitor/DMM-joined electronic circuit. A sandwich-type immunoreaction with target PSA between the immobilized primary antibody and glucose oxidase (GOx)-labeled detection antibody was initially carried out in one of the two half-cells. Accompanying the sandwiched immunocomplex, the conjugated GOx could catalyze the oxidation of glucose, simultaneously resulting in the conversion of [Fe(CN)6]3− to [Fe(CN)6]4−. The difference in the concentrations of [Fe(CN)6]3−/[Fe(CN)6]4− in two half-cells automatically produced a voltage that was utilized to charge an external capacitor. With the closing circuit switch, the capacitor discharged through the DMM, which could provide a high instantaneous current. Under the optimal conditions, the resulting currents was indirectly proportional to the concentration of target PSA in the dynamic range of 0.05–7 ng mL−1 with a detection limit (LOD) of 6 pg mL−1. The reproducibility, precision, and selectivity were acceptable. In addition, the methodology was validated by analyzing 12 clinical serum specimens, receiving a good accordance with the referenced values for the detection of PSA.
Co-reporter:Li Hou, Zhuangqiang Gao, Mingdi Xu, Xia Cao, Xiaoping Wu, Guonan Chen, Dianping Tang
Biosensors and Bioelectronics 2014 Volume 54() pp:365-371
Publication Date(Web):15 April 2014
DOI:10.1016/j.bios.2013.11.014
•We construct a new impedimetric immunosensor for sensitive detection of low-abundance protein.•DNAzyme-functionalized gold–palladium hybrid nanostructures are used as molecular tags.•The nanotag-based catalytic precipitation method exhibits triple signal amplification.A highly sensitive and selective impedimetric immunosensor with triple signal amplification was designed for ultrasensitive detection of prostate-specific antigen (PSA) by using anti-PSA antibody and DNAzyme-functionalized gold–palladium hybrid nanotags (Ab2–AuPd–DNA). The signal was amplified based on the Ab2–AuPd–DNA toward the catalytic precipitation of 4-choloro-1-naphthol (4-CN). DNAzyme (as a kind of peroxidase mimic) could catalyze the oxidation of 4-CN, whilst AuPd hybrid nanostructures could not only provide a large surface coverage for immobilization of biomolecules but also promote 4-CN oxidation to some extent. The produced insoluble benzo-4-chlorohexadienone via 4-CN was coated on the electrode surface, and hindered the electron transfer between the solution and the electrode, thereby increasing the Faradaic impedance of the base electrode. Three labeling strategies including Ab2–AuNP, Ab2–AuPd and Ab2–AuPd–DNA were investigated for determination of PSA, and improved analytical features were obtained with the Ab2–AuPd–DNA strategy. Under optimal conditions, the dynamic concentration range of the impedimetric immunosensor spanned from 1.0 pg mL−1 to 50 ng mL−1 PSA with a detection limit of 0.73 pg mL−1. Intra- and inter-assay coefficients of variation were below 8.5% and 9.5%, respectively. Importantly, no significant differences at the 0.05 significance level were encountered in the analysis of 6 clinical serum specimens and 6 diluted standards between the impedimetric immunosensor and the commercialized electrochemiluminescent method for PSA detection.
Co-reporter:Jun Zhou, Juan Tang, Guonan Chen, Dianping Tang
Biosensors and Bioelectronics 2014 Volume 54() pp:323-328
Publication Date(Web):15 April 2014
DOI:10.1016/j.bios.2013.11.032
•A new immunoassay protocol is designed for electronic monitoring of biomarker.•Nanosilver-doped bovine serum albumin microspheres were used for the labeling of detection antibody.•The assay was implemented based on tyramine signal amplification strategy.A new sandwich-type electrochemical immunosensor based on nanosilver-doped bovine serum albumin microspheres (Ag@BSA) with a high ratio of horseradish peroxidase (HRP) and detection antibody was developed for quantitative monitoring of biomarkers (carcinoembryonic antigen, CEA, used in this case) by coupling enzymatic biocatalytic precipitation with tyramine signal amplification strategy on capture antibody-modified glassy carbon electrode. Two immunosensing protocols (with and without tyramine signal amplification) were also investigated for the detection of CEA and improved analytical features were acquired with tyramine signal amplification strategy. With the labeling method, the performance and factors influencing the electrochemical immunoassay were studied and evaluated in detail. Under the optimal conditions, the electrochemical immunosensor exhibited a wide dynamic range of 0.005–80 ng mL−1 toward CEA standards with a low detection limit of 5.0 pg mL−1. Intra- and inter-assay coefficients of variation were below 11%. No significant differences at the 0.05 significance level were encountered in the analysis of 6 clinical serum specimens and 6 spiked new-born cattle serum samples between the electrochemical immunoassay and the commercialized electrochemiluminescent immunoassay method for the detection of CEA.
Co-reporter:Libing Fu, Junyang Zhuang, Wenqiang Lai, Xiaohua Que, Minghua Lu and Dianping Tang
Journal of Materials Chemistry A 2013 vol. 1(Issue 44) pp:6123-6128
Publication Date(Web):17 Sep 2013
DOI:10.1039/C3TB21155J
A portable and quantitative monitoring protocol for sensitive detection of lead ions is designed, based on target-responsive cargo release from Pb2+-specific DNAzyme-capped mesoporous silica nanoparticles (MSNs), by coupling with a widely accessible personal glucose meter (PGM). Initially, glucose molecules are loaded into the pores of the MSNs, the pores are then capped with Pb2+-specific DNAzymes. Upon target introduction, the molecular gates open, resulting in release of the cargo from the pores. The released glucose can be quantitatively monitored using a portable PGM. Under optimal conditions, the as-prepared sensing platform presents good analytical properties for the determination of the target Pb2+ ions, and allows detection of Pb2+ at concentrations as low as 1.0 pM. Importantly, the portable sensing platform has the advantages of simple, on-site, user-friendly and low-cost assessment and has tremendous potential for quantitative detection of non-glucose targets by the public.
Co-reporter:Junyang Zhuang, Libing Fu, Wenqiang Lai, Dianping Tang and Guonan Chen
Chemical Communications 2013 vol. 49(Issue 95) pp:11200-11202
Publication Date(Web):08 Oct 2013
DOI:10.1039/C3CC46869K
Target-stimulated metallic HgS nanostructures formed on the DNA-based polyion complex (PIC) membrane were for the first time utilized as an efficient scheme for impedimetric detection of hydrogen sulfide (H2S) by coupling insoluble precipitation with sensitivity enhancement.
Co-reporter:Wenqiang Lai, Dianping Tang, Libing Fu, Xiaohua Que, Junyang Zhuang and Guonan Chen
Chemical Communications 2013 vol. 49(Issue 42) pp:4761-4763
Publication Date(Web):05 Apr 2013
DOI:10.1039/C3CC41708E
Squaric acid, a 2-dimensional planar structure of squarate C4O4 units linked by protons in a layered sheet, was utilized for the first time as a catalytic substrate for ultrasensitive electronic determination of low-abundance proteins by coupling a target-induced electrocatalytic reaction with the in situ cycling signal amplification strategy.
Co-reporter:Juan Tang, Jun Zhou, Qunfang Li, Dianping Tang, Guonan Chen and Huanghao Yang
Chemical Communications 2013 vol. 49(Issue 15) pp:1530-1532
Publication Date(Web):03 Jan 2013
DOI:10.1039/C2CC38493K
Platinum–cerium oxide hybrid nanocatalysts (CeO2–Pt) were for the first time designed as bionanolabels for highly efficient electrochemical immunosensing of low-abundance proteins coupling nanocatalyst-based redox cycling with in situ signal amplification strategy.
Co-reporter:Bing Zhang, Bingqian Liu, Jun Zhou, Juan Tang, and Dianping Tang
ACS Applied Materials & Interfaces 2013 Volume 5(Issue 10) pp:4479
Publication Date(Web):April 17, 2013
DOI:10.1021/am401027w
A new signal-on immunoassay protocol for sensitive electronic detection of alpha-fetoprotein (AFP) was developed by coupling with metal sulfide nanolabels and a silver nanocluster (AgNC)-based rolling circle amplification (RCA) strategy. Initially, a sandwiched immunocomplex was formed on a primary antibody-coated microplate using a PbS nanoparticle-labeled polyclonal anti-AFP antibody (PbS-pAb2) as the detection antibody, and then the carried PbS-pAb2 was dissolved by acid to release a large number of lead ions, which could induce the cleavage of lead-specific DNAzyme immobilized on the electrode. The residual single-stranded DNA on the electrode could be used as the primer to produce numerous repeated oligonucleotide sequences via the RCA reaction for the hybridization with many AgNC-labeled detection probes, resulting in the amplification of the electronic signal due to the unique properties of silver nanoclusters. Under optimal conditions, the developed immunoassay exhibited high sensitivity for the detection of AFP with a dynamic range of 0.001–200 ng mL–1 and a detection limit (LOD) of 0.8 pg mL–1. Intra-assay and interassay coefficients of variation were below 8.0% and 10%, respectively. Importantly, the methodology was evaluated by analyzing 12 clinical serum specimens, and no significant differences were encountered in comparison with the conventional enzyme-linked immunosorbent assay (ELISA) method.Keywords: electrochemical immunoassay; low-abundance protein; metal sulfide nanoparticles; rolling circle amplification; silver nanoclusters;
Co-reporter:Jun Zhou, Wenqiang Lai, Junyang Zhuang, Juan Tang, and Dianping Tang
ACS Applied Materials & Interfaces 2013 Volume 5(Issue 7) pp:2773
Publication Date(Web):March 14, 2013
DOI:10.1021/am400652g
A novel and in situ amplified immunoassay strategy with quadruple signal amplification was designed for highly efficient electrochemical detection of low-abundance proteins (carcinoembryonic antigen, CEA, as a model) by using nanogold-functionalized DNAzyme concatamers with redox-active intercalators. To construct such an in situ amplification system, streptavidin-labeled gold nanoparticles (AuNP-SA) were initially used for the labelling of initiator strands (S0) and detection antibody (mAb2) with a large ratio (mAb2–AuNP–S0), and then two auxiliary DNA strands S1 and S2 were designed for in situ propagation of DNAzyme concatamers with the hemin/G-quadruplex format. The quadruple signal amplification was implemented by using the avidin–biotin chemistry, nanogold labels, DNA concatamers, and DNAzymes. In the presence of target CEA, the sandwiched immunocomplex was formed between the immobilized primary antibodies on the electrode and the conjugated detection antibodies on the mAb2–AuNP–S0. The carried S0 initiator strands could progress a chain reaction of hybridization events between alternating S1/S2 DNA strands to form a nicked double-helix. Upon addition of hemin, the hemin-binding aptamers could be bound to form the hemin/G-quadruplex-based DNAzymes. The formed double-helix DNA polymers could cause the intercalation of numerous electroactive methylene blue molecules. During the electrochemical measurement, the formed DNAzymes could catalyze the reduction of H2O2 in the solution to amplify the electrochemical signal of the intercalated methylene blue. Under optimal conditions, the electrochemical immunoassay exhibited a wide dynamic range of 1.0 fg mL–1 to 20 ng mL–1 toward CEA standards with a low detection limit of 0.5 fg mL–1. Intra-assay and inter-assay coefficients of variation (CV) were less than 8.5% and 11.5%, respectively. No significant differences at the 0.05 significance level were encountered in the analysis of 14 clinical serum specimens between the developed immunoassay and commercialized electrochemiluminescent (ECL) method for detection of CEA.Keywords: DNAzyme concatamers; electrochemical immunoassay; gold nanoparticles; quadruple single amplification;
Co-reporter:Mingdi Xu, Junyang Zhuang, Xian Chen, Guonan Chen and Dianping Tang
Chemical Communications 2013 vol. 49(Issue 66) pp:7304-7306
Publication Date(Web):24 Jun 2013
DOI:10.1039/C3CC43205J
A novel difunctional DNA–nanogold (AuNP) dendrimer with a hemin–G-quadruplex was for the first time utilized as the nanotag for the in situ amplified electronic signal for nucleic acid detection by coupling high-efficiency DNAzyme with the intercalated methylene blue (MB).
Co-reporter:Dianping Tang, Bing Zhang, Juan Tang, Li Hou, and Guonan Chen
Analytical Chemistry 2013 Volume 85(Issue 14) pp:6958
Publication Date(Web):June 21, 2013
DOI:10.1021/ac401599t
A novel displacement-type quartz crystal microbalance (QCM) immunosensing strategy, based on glucose and its analogue dextran for concanavalin A (ConA) binding sites, was designed for ultrasensitive monitoring of small molecular biotoxins (brevetoxin B, PbTx-2, used as a model) with signal amplification on a graphene-functionalized sensing interface. To construct such a QCM immunosensing platform, phenoxy-functionalized dextran (DexP) was initially assembled onto the surface of graphene-coated QCM probe via the π-stacking interaction, and ConA-labeled monoclonal mouse anti-PbTx-2 capture antibody was then immobilized on the DexP-modified probe by dextran–ConA binding. Gold nanoparticle heavily functionalized with glucoamylase and bovine serum albumin–PbTx-2 (PbTx-2–BSA) conjugate was employed as the trace tag. A competitive-type immunoassay format was adopted for the online monitoring of PbTx-2 between anti-PbTx-2 antibody immobilized on the QCM probe and PbTx-2–BSA labeled on the gold nanoparticle. Accompanying the gold nanoparticle, the carried glucoamylase could hydrolyze amylopectin in glucose. The produced glucose competed with dextran for ConA and displaced the ConA–streptavidin–anti-PbTx-2 complex from the QCM probe, resulting in the frequency change. Under optimal conditions, the frequency of the QCM immunosensor was indirectly proportional to the concentration of target PbTx-2 in the sample and exhibited a dynamic range from 1.0 pg·mL–1 to 10 ng·mL–1 with a detection limit (LOD) of 0.6 pg·mL–1 at the 3Sblank level. Intra- and interassay coefficients of variation were below 7.5% and 9.5%, respectively. In addition, the methodology was evaluated for analysis of PbTx-2 in 15 spiked seafood samples and showed good accordance between results obtained by the displacement-type QCM immunosensor and a commercialized enzyme-linked immunosorbent assay (ELISA) method.
Co-reporter:Zhuangqiang Gao, Mingdi Xu, Li Hou, Guonan Chen, and Dianping Tang
Analytical Chemistry 2013 Volume 85(Issue 14) pp:6945
Publication Date(Web):June 14, 2013
DOI:10.1021/ac401433p
A novel reverse colorimetric immunoassay (RCIA) strategy was for the first time designed and utilized for sensitive detection of low-abundance protein (prostate-specific antigen, PSA, used in this case) in biological fluids by coupling highly catalytic efficient catalase with magnetic bead-based peroxidase mimics. To construct such a RCIA system, two nanostructures including magnetic beads and gold nanoparticles were first synthesized and functionalized with anti-PSA capture antibody and catalase/anti-PSA detection antibody, respectively. Thereafter, a specific sandwich-type immunoassay format was employed for determination of PSA by using functional gold nanoparticles as enzymatic bioreactors and anti-PSA-conjugated magnetic beads as a colorimetric developer. The carried catalase, followed by the sandwiched immunocomplex, partially consumed the added hydrogen peroxide in the detection solution, which slowed down the catalytic efficiency of magnetic bead-based peroxidase mimics toward TMB/H2O2, thereby weakening the visible color and decreasing the colorimetric density. Different from conventional colorimetric immunoassay, the RCIA method determined the residual hydrogen peroxide in the substrate after consumption. Under the optimal conditions, the developed RCIA exhibited a wide dynamic range of 0.05–20 ng mL–1 toward PSA with a detection limit of 0.03 ng mL–1 at the 3Sblank level. Intra- and interassay coefficients of variation were below 6.1% and 9.3%, respectively. Additionally, the methodology was further validated for the analysis of 12 PSA clinical serum specimens, giving results in good accordance with those obtained by the commercially available enzyme-linked immunosorbent assay (ELISA) method.
Co-reporter:Bing Zhang, Bingqian Liu, Jiayao Liao, Guonan Chen, and Dianping Tang
Analytical Chemistry 2013 Volume 85(Issue 19) pp:9245
Publication Date(Web):September 2, 2013
DOI:10.1021/ac4019878
A novel homogeneous immunoassay protocol was designed for quantitative monitoring of small molecular biotoxin (brevetoxin B, PbTx-2, as a model) by using target-responsive cargo release from polystyrene microsphere-gated mesoporous silica nanocontainer (MSN). Initially, monoclonal mouse anti-PbTx-2 capture antibody was covalently conjugated onto the surface of MSN (mAb-MSN), and the electroactive cargo (methylene blue, MB) was then trapped in the pores of mAb-MSN by using aminated polystyrene microspheres (APSM) based on the electrostatic interaction. Upon addition of target PbTx-2, the positively charged APSM was displaced from the negatively charged mAb-MSN because of the specific antigen–antibody reaction. Thereafter, the molecular gate was opened, and the trapped methylene blue was released from the pores. The released methylene blue could be monitored by using a square wave voltammetry (SWV) in a homemade microelectrochemical detection cell. Under optimal conditions, the SWV peak current increased with the increasing of PbTx-2 concentration in the range from 0.01 to 3.5 ng mL–1 with a detection limit (LOD) of 6 pg mL–1 PbTx-2 at the 3Sblank criterion. Intra- and interassay coefficients of variation with identical batches were ≤6% and 9.5%, respectively. The specificity and sample matrix interfering effects were acceptable. The analysis in 12 spiked seafood samples showed good accordance between results obtained by the developed immunoassay and a commercialized enzyme-linked immunosorbent assay (ELISA) method. Importantly, the target-responsive controlled release system-based electrochemical immunoassay (CRECIA) offers a promising scheme for the development of advanced homogeneous immunoassay without the sample separation and washing procedure.
Co-reporter:Dianping Tang, Bingqian Liu, Reinhard Niessner, Peiwu Li, and Dietmar Knopp
Analytical Chemistry 2013 Volume 85(Issue 21) pp:10589
Publication Date(Web):September 26, 2013
DOI:10.1021/ac402713a
A new fluorescence immunoassay strategy based on a target-induced displacement reaction with cargo release from protein-gated carbohydrate-functionalized magnetic mesoporous silica nanoparticles (MMSN) was developed for sensitive detection of small molecular mycotoxins (aflatoxin B1, AFB1 used in this case). To construct such an assay system, MMSN was initially functionalized with mannose-terminated silanes, then capped with biotinylated concanavalin A (Con A) entrapped rhodamine B (RB) within the pores through the carbohydrate–protein interaction, and then biotinylated monoclonal anti-AFB1 capture antibody was conjugated to Con A-functionalized MMSN by the streptavidin–biotin chemistry. Gold nanoparticles (AuNP) heavily functionalized with invertase and bovine serum albumin–AFB1 conjugate were utilized as the trace tag. With AFB1 introduction, a competitive immunoreaction for the immobilized anti-AFB1 antibody on the MMSN was started between target analyte and the labeled AFB1 on the AuNP. Accompanied by AuNP, the carried invertase hydrolyzed sucrose in glucose and fructose. The generated glucose competed with the mannose for Con A and displaced the Con A–antibody complex from the MMSN, resulting in the opening of molecular gates owing to the uncapping of MMSN, thereby the entrapped RB could release from the pores. The released RB could be quantitatively determined by a fluorometer. Under optimal conditions, the fluorescence intensity decreased with the increasing AFB1 concentration in the range from 0.01 to 5 ng mL–1 with a detection limit (LOD) of 8 pg mL–1 at the 3sblank criterion. Intra- and interbatch assay precisions were lower than 9 and 9.5% (CV), respectively. The method featured unbiased identification of negative (blank) and positive samples. No significant differences at the 0.05 significance level were encountered in the analysis of naturally contaminated peanut samples between the fluorescence immunoassay and a commercialized enzyme-linked immunosorbent assay (ELISA) method.
Co-reporter:Bing Zhang, Bingqian Liu, Junyang Zhuang, and Dianping Tang
Bioconjugate Chemistry 2013 Volume 24(Issue 4) pp:678
Publication Date(Web):March 4, 2013
DOI:10.1021/bc3006557
This work reports a novel electrochemical immunoassay protocol with signal amplification for determination of low-abundance protein (free prostate-specific antigen, PSA, used as a model) with high sensitivity and high selectivity by coupling metal sulfide (PbS)-based nanolabels with cleavage of the corresponding lead ion-induced DNAzymes. The assay mainly consists of an antigen–antibody immunoreaction with metal nanolabel in a transparent 96-well polystyrene microplate, the release of metal ions from the nanolabel, and cleavage of metal ion-induced DNAzyme. The signal is amplified by the labeled redox tag (ferrocene) on the DNAzyme-based sensor. In the presence of target analyte, the sandwiched immunocomplex can be formed between the primary antibody on the microplate and the corresponding metal sulfide nanolabel. The carried nanolabel can release numerous metal ions by acid, and induce the cleavage of the corresponding DNAzyme, thus resulting in the change of electrochemical signal. Under optimal conditions, the DNAzyme-based immunoassay presents an obvious electrochemical response for the detection of PSA, and allows detection of PSA at a concentration as low as 0.1 pg mL–1. Intra-assay and interassay coefficients of variation (CV) were less than 9.5% and 10%, respectively. No significant differences at the 0.05 significance level were encountered in the analysis of 12 clinical serum specimens between the developed immunoassay and a commercially available enzyme-linked immunosorbent assay (ELISA).
Co-reporter:Xiaomei Pei, Bing Zhang, Juan Tang, Bingqian Liu, Wenqiang Lai, Dianping Tang
Analytica Chimica Acta 2013 Volume 758() pp:1-18
Publication Date(Web):3 January 2013
DOI:10.1016/j.aca.2012.10.060
Methods based on sandwich-type immunosensors and immunoassays have been developed for detection of multivalent antigens/analytes with more than one eptiope due to the use of two matched antibodies. High-affinity antibodies and appropriate labels are usually employed for the amplification of detectable signal. Recent research has looked to develop innovative and powerful novel nanoparticle labels, controlling and tailoring their properties in a very predictable manner to meet the requirements of specific applications. This articles reviews recent advances, exploiting nanoparticle labels, in the sandwich-type immunosensors and immunoassays. Routine approaches involve noble metal nanoparticles, carbon nanomaterials, semiconductor nanoparticles, metal oxide nanostructures, and hybrid nanostructures. The enormous signal enhancement associated with the use of nanoparticle labels and with the formation of nanoparticle-antibody-antigen assemblies provides the basis for sensitive detection of disease-related proteins or biomolecules. Techniques commonly rely on the use of biofunctionalized nanoparticles, inorganic-biological hybrid nanoparticles, and signal tag-doped nanoparticles. Rather than being exhaustive, this review focuses on selected examples to illustrate novel concepts and promising applications. Approaches described include the biofunctionalized nanoparticles, inorganic-biological hybrid nanoparticles, and signal tage-doped nanoparticles. Further, promising application in electrochemical, mass-sensitive, optical and multianalyte detection are discussed in detail.Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Sandwich-type immunosensors and immunoassays exploiting nanostructure labels. ► Nanolabel-based electrochemical immunosensing and immunoassay. ► Nanolabel-based optical immunosensors and immunoassays. ► Nanolabel-based mass-sensitive immunosensing. ► Nanolabel-based multianalyte immunoassays.
Co-reporter:Junyang Zhuang, Libing Fu, Mingdi Xu, Huanghao Yang, Guonan Chen, Dianping Tang
Analytica Chimica Acta 2013 Volume 783() pp:17-23
Publication Date(Web):14 June 2013
DOI:10.1016/j.aca.2013.04.049
•A new signal-on metallobioassay was developed for detection of nucleic acids.•Target-triggered long-range self-assembled DNA nanostructures are used for amplification of electronic signal.•Hybridization chain reaction is utilized for construction of long-range DNA nanostructures.Methods based on metal nanotags have been developed for metallobioassay of nucleic acids, but most involve complicated labeling or stripping procedures and are unsuitable for routine use. Herein, we report the proof-of-concept of a novel and label-free metallobioassay for ultrasensitive electronic determination of human immunodeficiency virus (HIV)-related gene fragments at an ultralow concentration based on target-triggered long-range self-assembled DNA nanostructures and DNA-based hybridization chain reaction (HCR). The signal is amplified by silver nanotags on the DNA duplex. The assay mainly consists of capture probe, detection probe, and two different DNA hairpins. In the presence of target DNA, the capture probe immobilized on the sensor sandwiches target DNA with the 3′ end of detection probe. Another exposed part of detection probe at the 5′ end opens two alternating DNA hairpins in turn, and propagates a chain reaction of hybridization events to form a nicked double-helix. Finally, numerous silver nanotags are immobilized onto the long-range DNA nanostructures, each of which produces a strong electronic signal within the applied potentials. Under optimal conditions, the target-triggered long-range DNA nanostructures present good electrochemical behaviors for the detection of HIV DNA at a concentration as low as 0.5 fM. Importantly, the outstanding sensitivity can make this approach a promising scheme for development of next-generation DNA sensors without the need of enzyme labeling or fluorophore labeling.
Co-reporter:Zhuangqiang Gao, Mingdi Xu, Li Hou, Guonan Chen, Dianping Tang
Analytica Chimica Acta 2013 Volume 776() pp:79-86
Publication Date(Web):7 May 2013
DOI:10.1016/j.aca.2013.03.034
•We report a new colorimetric immunoassay of rabbit IgG.•Irregular-shaped platinum nanostructures were used as peroxidase mimics.•The assay was implemented based on nanocatalysts.Enzyme-linked immunosorbent assay (ELISA) methods based on natural enzyme-labeled probes have been applied in the immunoassays, but most have some inevitable limitations (e.g. harsh preparation, purification and storage) and are unsuitable for routine use. Herein we synthesized a new class of irregular-shaped platinum nanoparticles (ISPtNP) with a mean length of 7.0 nm and a narrowing width from 2.0 to 5.0 nm along the longitudinal axes, which were utilized as peroxidase-like mimics for the development of colorimetric immunoassays. Compared with bioactive horseradish peroxidase (HRP), the synthesized ISPtNP exhibited a low Km value (~0.12 mM) and a high Kcat value (~2.27 × 104 s−1) for 3,3′,5,5′-tetramethylbenzidine (TMB) with strong thermal stability and pH tolerance. The catalytic mechanism of the ISPtNP toward TMB/H2O2 was for the first time discussed and deliberated in this work. Based on a sandwich-type assay format, two types of colorimetric immunoassay protocols were designed and developed for the detection of rabbit IgG (RIgG, as a model) by using the synthesized ISPtNP and conventional HRP as the labeling of detection antibodies, respectively. Similar detection limits (LODs) of 2.5 ng mL−1 vs. 1.0 ng mL−1 were obtained toward RIgG with the ISPtNP labeling compared to HRP format. Intra- and inter-assay coefficients of variation were less than 13%. Importantly, the ISPtNP-based assay system could be suitable for use in a mass production of miniaturized lab-on-a-chip devices and open new opportunities for protein diagnostics and biosecurity.
Co-reporter:Juan Tang, Xian Chen, Jun Zhou, Qunfang Li, Guonan Chen and Dianping Tang
Analyst 2013 vol. 138(Issue 15) pp:4327-4333
Publication Date(Web):13 May 2013
DOI:10.1039/C3AN00706E
Multifunctionalized thionine-modified cerium oxide (Thi–CeO2) nanostructures with redox ability and catalytic activity were designed as the bionanolabels for in situ amplified electronic signal of low-abundance protein (carcinoembryonic antigen, CEA, used as a model) based on a cerium oxide-triggered ‘one-to-many’ catalytic cycling strategy. Initially, the carried CeO2 nanoparticles autocatalytically hydrolyzed the phosphate ester bond of L-ascorbic acid 2-phosphate (AAP) to produce a new reactant (L-ascorbic acid, AA), then the generated AA was electrochemically oxidized by the assembled thionine on the Thi–CeO2, and the resultant product was then reduced back to AA by the added tris(2-carboxyethy)phosphine (TCEP). The catalytic cycling could be re-triggered by the thionine and TCEP, resulting in amplification of the electrochemical signal. Under the optimized conditions, the electrochemical immunosensor exhibited a wide linear range of 0.1 pg mL−1 to 80 ng mL−1 with a low detection limit of 0.08 pg mL−1 CEA at the 3σblank level. In addition, the methodology was evaluated for the analysis of clinical serum samples, and was in good accordance with values obtained using the commercialized enzyme-linked immunosorbent assay (ELISA) method.
Co-reporter:Dianping Tang, Yuling Cui and Guonan Chen
Analyst 2013 vol. 138(Issue 4) pp:981-990
Publication Date(Web):12 Dec 2012
DOI:10.1039/C2AN36500F
Recent research has looked to develop innovative, powerful and novel biofunctionalized nanoparticles, controlling and tailoring their properties in a very predictable manner to meet the needs of clinic immunoassays in the biomedical field. This minireview briefly summarizes recent advances covering the last 3 years, exploiting nanoparticle-based electrochemical, optical, mass-sensitive, colorimetric and immunodipstick assays. The enormous signal enhancement associated with the use of nanoparticles and formation of nanoparticle–antibody–antigen assemblies provide the basis for sensitive detection of disease-related proteins or biomarkers. Rather than being exhaustive, this minireview focuses on selected examples to illustrate novel concepts and promising applications. Finally, a small amount of speculation of possible future developments in nanoparticle-based immunoassays is provided.
Co-reporter:Xiaohua Que, Xian Chen, Libing Fu, Wenqiang Lai, Junyang Zhuang, Guonan Chen, Dianping Tang
Journal of Electroanalytical Chemistry 2013 Volume 704() pp:111-117
Publication Date(Web):1 September 2013
DOI:10.1016/j.jelechem.2013.06.023
•A sensitive electrochemical immunoassay is developed for detection of tetracycline residues.•Platinum-catalyzed hydrogen evolution reaction is used for signal amplification.•Graphene-enriched platinum nanoparticles is used for the labeling of biomolecules.A new signal amplification strategy for sensitive electrochemical determination of tetracycline (TC) was developed by using platinum-catalyzed hydrogen evolution reaction (HER) on an anti-TC antibody-modified immunosensor. To construct such a HER, platinum nanoparticles were initially deposited to graphene nanosheets, and the as-synthesized platinum/graphene nanosheets (PtGN) were then used for the labeling of tetracycline-bovine serum albumin conjugates (TC–BSA). With a competitive immunoassay format, the resulting immunosensor was immersed into a platinum developer solution containing 1.0 mM PtCl42-, 0.1 M formate (reductant) and 0.5% Tween 80 (pH 6.5) to promote the platinum growth. The amplified electrochemical signal mainly derived from the platinum-catalyzed HER in an acidic medium containing 10 mM HCl and 1.0 M KCl. Two labeling methods and assay protocols including Pt-labeled TC–BSA and PtGN-labeled TC–BSA with or without the platinum enhancement were investigated for determination of target TC, respectively, and improved analytical features were obtained with graphene nanosheets and platinum growth mechanism. With PtGN-labeled TC–BSA, the effects of incubation time for antigen–antibody reaction and deposition time of platinum on the currents of the immunosensors were also studied. The strong attachment of TC–BSA to the PtGN resulted in a good repeatability and intermediate precision down to 9.8%. The dynamic concentration range spanned from 0.05 ng/mL to 100 ng/mL tetracycline with a low detection limit of 6 pg/mL at the 3sblank level. In addition, the methodology was further validated with tetracycline spiked samples including honey, milk and peanut, and the recoveries were 86–118%.
Co-reporter:Dr. Bing Zhang; Dianping Tang; Irina Yu. Goryacheva; Reinhard Niessner; Dietmar Knopp
Chemistry - A European Journal 2013 Volume 19( Issue 7) pp:2496-2503
Publication Date(Web):
DOI:10.1002/chem.201203131
Abstract
A new anodic-stripping voltammetric immunoassay protocol for detection of IgG1, as a model protein, was designed by using CdS quantum dot (QD) layer-by-layer assembled hollow microspheres (QDHMS) as molecular tags. Initially, monoclonal anti-human IgG1 specific antibodies were anchored on amorphous magnetic beads preferably selective to capture Fab of IgG1 analyte from the sample. For detection, monoclonal anti-human IgG1 (Fc-specific) antibodies were covalently coupled to the synthesized QDHMS. In a sandwich-type immunoassay format, subsequent anodic-stripping voltammetric detection of cadmium released under acidic conditions from the coupled QDs was conducted at an in situ prepared mercury film electrode. The immunoassay combines highly efficient magnetic separation with signal amplification by the multilayered QD labels. The dynamic concentration range spanned from 1.0 fg mL−1 to 1.0 μg mL−1 of IgG1 with a detection limit of 0.1 fg mL−1. The electrochemical immunoassay showed good reproducibility, selectivity, and stability. The analysis of clinical serum specimens revealed good accordance with the results obtained by an enzyme-linked immunosorbent assay method. The new immunoassay is promising for enzyme-free, and cost-effective analysis of low-abundance biomarkers.
Co-reporter:Dianping Tang, Li Hou, Reinhard Niessner, Mingdi Xu, Zhuangqiang Gao, Dietmar Knopp
Biosensors and Bioelectronics 2013 Volume 46() pp:37-43
Publication Date(Web):15 August 2013
DOI:10.1016/j.bios.2013.02.027
A novel multiplexed stripping voltammetric immunoassay protocol was designed for the simultaneous detection of multiple biomarkers (CA 125, CA 15-3, and CA 19-9 used as models) using PAMAM dendrimer-metal sulfide quantum dot (QD) nanolabels as distinguishable signal tags and trifunctionalized magnetic beads as an immunosensing probe. The probe was prepared by means of co-immobilization of primary monoclonal anti-CA 125, anti-CA 15-3 and anti-CA 19-9 antibodies on a single magnetic bead. The PAMAM dendrimer-metal sulfide QD nanolabels containing CdS, ZnS and PbS were synthesized by using in situ synthesis method, which were utilized for the labeling of polyclonal rabbit anti-CA 125, anti-CA 15-3 and anti-CA 19-9 detection antibodies, respectively. A sandwich-type immunoassay format was adopted for the simultaneous determination of target biomarkers in a low-binding microtiter plate. The subsequent anodic stripping voltammetric analysis of cadmium, zinc, and lead components released by acid from the corresponding QD nanolabels was conducted at an in situ prepared mercury film electrode based on the difference of peak potentials. Experimental results indicated that the multiplexed immunoassay enabled the simultaneous detection of three cancer biomarkers in a single run with wide dynamic ranges of 0.01–50 U mL−1 and detection limits (LODs) of 0.005 U mL−1. Intra-assay and inter-assay coefficients of variation (CVs) were less than 7.2% and 10.4%, respectively. No significant differences at the 0.05 significance level were encountered in the analysis of 10 clinical serum specimens between the multiplexed immunoassay and a commercially available enzyme-linked immunosorbent assay (ELISA).Highlights► We introduce a new multiplexed voltammetric immunoassay protocol for simultaneous detection of multiple biomarkers. ► PAMAM dendrimer-metal sulfide quantum dot (QD) nanolabels were used as distinguishable molecular tags. ► Trifunctionalized magnetic beads were used as immunosensing probes.
Co-reporter:Huafeng Chen, Zhuangqiang Gao, Yuling Cui, Guonan Chen, Dianping Tang
Biosensors and Bioelectronics 2013 Volume 44() pp:108-114
Publication Date(Web):15 June 2013
DOI:10.1016/j.bios.2012.12.054
A new electrochemical immunosensing protocol was designed for detection of carcinoembryonic antigen (CEA, as a model protein) by using graphene-carried poly(o-phenylenediamine)/gold hybrid nanosheets (GNPGs) as signal tags on the hierarchical dendritic gold microstructures (HDGMs)-modified glassy carbon electrode. To prepare the signal tags, poly(o-phenylenediamine) molecules were initially immobilized on the surface of graphene nanosheets via the π-stacking interaction. Then gold nanoparticles were assembled onto the poly(o-phenylenediamine)-modified graphene nanosheets, which were used for the labeling of anti-CEA detection antibodies and horseradish peroxidase (HRP). The as-prepared GNPGs were characterized by using atomic force microscopy (AFM), transmission electron microscopy (TEM) and UV–vis absorption spectroscopy. The assay was carried out with a sandwich-type immunoassay format in pH 5.5acetic acid-buffered saline solutions containing 2.5 mmol L−1 H2O2. Under optimal conditions, the electrochemical immunoassay exhibited a wide dynamic range of 0.005–80 ng mL−1 toward CEA standards with a low detection limit of 5.0 pg mL−1. Intra- and inter-assay coefficients of variation were less than 11.5%. No significant difference at the 0.05 significance level was encountered in the analysis of 6clinical serum specimens and 6spiked blank new born cattle serum specimens between the developed immunoassay and commercially available electrochemiluminescent (ECL) method for the detection ofCEA.Highlights► We introduce a new electrochemical immunoassay protocol for sensitive detection of low-abundance proteins. ► Using graphene-carried poly(o-phenylenediamine)/gold hybrid nanosheets as molecular tags. ► Design of redox-active nanolabels.
Co-reporter:Bingqian Liu, Dianping Tang, Bing Zhang, Xiaohua Que, Huanghao Yang, Guonan Chen
Biosensors and Bioelectronics 2013 Volume 41() pp:551-556
Publication Date(Web):15 March 2013
DOI:10.1016/j.bios.2012.09.021
Redox-active magnetic molecularly imprinted polymer (mMIP) nanospheres were first synthesized and functionalized with streptomycin templates for highly efficient electrochemical determination of streptomycin residues (STR) in food by coupling with bioelectrocatalytic reaction of enzymes for signal amplification. The mMIP nanospheres were synthesized by using Au(III)-promoted molecularly imprinted polymerization with STR templates on magnetic beads. Based on extraction of template molecules from the mMIP surface, the imprints toward STR templates were formed. The assay was implemented with a competitive-type assay format. Upon addition of streptomycin, the analyte competed with glucose oxidase-labeled streptomycin (GOX-STR) for molecular imprints on the mMIP nanospheres. With the increasing streptomycin in the sample, the conjugation amount of GOX-STR on the mMIP nanospheres decreased, leading to the change in the bioelectrocatalytic current relative to glucose system. Under optimal conditions, the catalytic current was proportional to STR level in the sample, and exhibited a dynamic range of 0.05–20 ng mL−1 with a detection limit of 10 pg mL−1 STR (at 3sB). Intra- and inter-assay coefficients of variation were below 12%. The assayed results for STR spiked samples including milk and honey with the mMIP-based sensor were received a good accordance with the results obtained from the referenced high-performance liquid chromatography (HPLC) method.Highlights► Au(III)-promoted magnetic molecularly imprinted polymer nanospheres. ► Magneto-controlled electrochemical sensor. ► Hybrid nanostructures-based assay for small molecules. ► Bioelectrocatalytic reaction of enzymes for signal amplification.
Co-reporter:Libing Fu, Dianping Tang, Junyang Zhuang, Wenqiang Lai, Xiaohua Que, Guonan Chen
Biosensors and Bioelectronics 2013 Volume 47() pp:106-112
Publication Date(Web):15 September 2013
DOI:10.1016/j.bios.2013.03.008
•A novel signal-on electrochemical DNA detection method has been developed.•Isothermal circular strand-displacement polymerization is utilized.•Hybridization-induced recycling is integrated for signal amplification.This works reports a new signal-on amplification strategy for sensitive electronic detection of nucleic acid based on the isothermal circular strand-displacement polymerization (ICSDP) reaction. The assay mainly involves a hybridization of ferrocene-labeled hairpin DNA with blocker DNA, a strand-displacement process with target DNA, and an ICSDP-based polymerization reaction. The signal is amplified by the labeled ferrocene on the hairpin probe with target recycling. Upon addition of target analyte, the blocker DNA is initially displaced by target DNA from the hairpin/blocker DNA duplex owing to the difference of the folding free energy, then the newly formed target/blocker DNA duplex causes the ICSDP reaction with the aid of the primer and polymerase, and then the released target DNA retriggers the strand-displacement for target recycling. Numerous ferrocene molecules are close to the electrode surface due to the reformation of hairpin DNA, each of which produces an electronic signal within the applied potentials, thereby resulting in the amplification of electrochemical signal. Under the optimal conditions, the ICSDP-based amplification method displays good electrochemical responses for detection of target DNA at a concentration as low as 0.03 pM.
Co-reporter:Junyang Zhuang, Libing Fu, Mingdi Xu, Qian Zhou, Guonan Chen, Dianping Tang
Biosensors and Bioelectronics 2013 Volume 45() pp:52-57
Publication Date(Web):15 July 2013
DOI:10.1016/j.bios.2013.01.039
A novel magneto-controlled electrochemical DNA biosensor is designed for the ultrasensitive detection of lead coupling a lead-specific DNAzyme with DNA-based hybridization chain reaction (HCR). To construct such a magnetic lead sensor, DNAzyme-based molecular beacons, selective to cleavage in the presence of Pb2+, are initially immobilized onto magnetic beads, which were used as the recognition elements. Upon addition of target lead, catalytic cleavage of substrate DNA segments in the double-stranded DNAzymes results in the capture of the initiator strands via the conjugated catalytic strands on magnetic beads. The captured DNA initiator strands trigger the hybridization chain reaction between two alternating hairpin DNA structures labeled with ferrocene to form a nicked double-helix on the magnetic beads. Numerous ferrocene molecules are formed on the neighboring probes, each of which produces an electrochemical signal within the applied potential. Under optimal conditions, the electrochemical signal of the magnetic lead sensor increases with the increasing lead level in the sample, and exhibits a linear response over a Pb2+ concentration range of 0.1–75 nM with a detection limit of 37 pM. Quantitative measurement of Pb2+ in the complex sample demonstrates the selectivity of the sensor scheme and points favorably to the application of such technologies to the analysis of environmental samples. The unique combination of a DNAzyme with hybridization chain reaction makes it possible to change the DNAzyme to select for other compounds of interest. This work represents the initial steps toward the creation of a robust field sensor for lead in groundwater or drinking water.Highlights► DNAzyme-based electrochemical sensor was developed for picomolar detection of lead (II). ► Hybridization chain reaction was used for the amplification of detectable signal. ► Magnetic bead-functionalized probe was employed as magneto-controlled electronic switch.
Co-reporter:Junyang Zhuang, Libing Fu, Dianping Tang, Mingdi Xu, Guonan Chen, Huanghao Yang
Biosensors and Bioelectronics 2013 Volume 39(Issue 1) pp:315-319
Publication Date(Web):15 January 2013
DOI:10.1016/j.bios.2012.07.015
A simple, sensitive and reusable electrochemical sensor was designed for determination of mercury (II) (Hg2+) by coupling target-induced conformational switch of DNA hairpins with thymine–Hg2+–thymine (T–Hg2+–T) coordination chemistry. The hairpin probe consisted of a stem of 6 base pairs enclosing a 14 nucleotide (nt) loop and an additional 12 nt sticky end at the 3′ end. Each hairpin was labeled with ferrocene (Fc) redox tag in the middle of the loop, which was immobilized on the electrode via self-assembly of the terminal thiol moiety at the 5′ end. In the presence of target analyte, Hg2+-mediated base pairs induced the conformational change from the sticky end to open the hairpins, resulting in the ferrocene tags close to the electrode for the increasing redox current. The strong coordination reaction of T–Hg2+–T resulted in a good repeatability and intermediate precision down to 10%. The dynamic concentration range spanned from 5.0 nM to 1.0 μM Hg2+ with a detection limit of 2.5 nM at the 3sblank level. The strategy afforded exquisite selectivity for Hg2+ against other environmentally related metal ions. Inspiringly, the developed sensor could be reused by introduction of iodide (I−).Highlights► DNA hairpins-based sensor for sensitive electrochemical determination of mercury (II). ► One-step electrochemical sensing of mercury (II). ► Signal-on electrochemical sensor. ► Target-induced conformational switch.
Co-reporter:Li Hou, Yuling Cui, Mingdi Xu, Zhuangqiang Gao, Jianxin Huang, Dianping Tang
Biosensors and Bioelectronics 2013 Volume 47() pp:149-156
Publication Date(Web):15 September 2013
DOI:10.1016/j.bios.2013.02.035
•We introduced a new impedimetric immunoassay for the detection of low-abundance proteins.•Enzymatic biocatalytic precipitation of insoluble products was formed.•Graphene oxide nanosheets were used as labels.A new sandwich-type impedimetric immunosensor based on functionalized graphene oxide nanosheets with a high ratio of horseradish peroxidase (HRP) and detection antibody was developed for the detection of carcinoembryonic antigen (CEA) by coupling with enzymatic biocatalytic precipitation of 4-chloro-1-naphthol (4-CN) on the captured antibody-modified glassy carbon electrode. Two molecular tags (with and without the graphene oxide nanosheets) were investigated for the detection of CEA and improved analytical features were acquired with the graphene-based labeling. With the labeling method, the performance and factors influencing the properties of the impedimetric immunosensors were also studied and evaluated. Under the optimal conditions, the dynamic concentration range of the impedimetric immunosensors spanned from 1.0 pg mL−1 to 80 ng mL−1 CEA with a detection limit (LOD) of 0.64 pg mL−1. Intra- and inter-assay coefficients of variation were less than 7.5% and 11%, respectively. Additionally, the methodology was evaluated for CEA analysis of 10 clinical serum samples and 5 diluted serum samples, receiving in a good accordance with the results obtained by the impedimetric immunoassay and the commercialized electrochemiluminescent method.
Co-reporter:Jun Zhou, Mingdi Xu, Dianping Tang, Zhuangqiang Gao, Juan Tang and Guonan Chen
Chemical Communications 2012 vol. 48(Issue 100) pp:12207-12209
Publication Date(Web):01 Nov 2012
DOI:10.1039/C2CC36820J
A label-free, non-enzyme immunosensing strategy is designed for ultrasensitive electronic detection of disease-related proteins (carcinoembryonic antigen as a model) by using gold nanoparticle-based bio-bar codes and an in situ amplified DNA-based hybridization chain reaction.
Co-reporter:Yuling Cui, Huafeng Chen, Dianping Tang, Huanghao Yang and Guonan Chen
Chemical Communications 2012 vol. 48(Issue 83) pp:10307-10309
Publication Date(Web):04 Sep 2012
DOI:10.1039/C2CC35351B
A novel and redox-active nanocatalyst, Au(III)-promoted polyaniline gold nanosphere (GPANG), was designed as the nanolabel for highly efficient electrochemical immunoassay of human IgG by coupling with electrocatalytic recycling of self-produced reactants.
Co-reporter:Juan Tang, Li Hou, Dianping Tang, Bing Zhang, Jun Zhou and Guonan Chen
Chemical Communications 2012 vol. 48(Issue 66) pp:8180-8182
Publication Date(Web):07 Jun 2012
DOI:10.1039/C2CC33390B
Hemin/G-quadruplex-based DNAzyme concatamers were utilized as electrocatalysts and biolabels to construct a sandwich-type electrochemical immunosensor for sensitive detection of IgG1 (as a model analyte).
Co-reporter:Juan Tang, Dianping Tang, Jun Zhou, Huanghao Yang and Guonan Chen
Chemical Communications 2012 vol. 48(Issue 20) pp:2627-2629
Publication Date(Web):16 Jan 2012
DOI:10.1039/C2CC17536C
A simple, novel, label-free impedimetric aptasensor with signal amplification is developed for ultrasensitive detection of small molecules on a carbon nanotubes-based sensing platform by combining target-induced release of the aptamers and nuclease cleavage-assisted target recycling.
Co-reporter:Bingqian Liu, Yuling Cui, Dianping Tang, Huanghao Yang and Guonan Chen
Chemical Communications 2012 vol. 48(Issue 20) pp:2624-2626
Publication Date(Web):16 Jan 2012
DOI:10.1039/C2CC17790K
A redox-active Au(III)-assisted core–shell iron oxide@poly(o-phenylenediamine) nanostructure was designed as a sensing platform for ultrasensitive electrochemical detection of small molecules (ATP, used as a model here) by coupling with DNase I-catalyzed target recycling.
Co-reporter:Bing Zhang, Bingqian Liu, Dianping Tang, Reinhard Niessner, Guonan Chen, and Dietmar Knopp
Analytical Chemistry 2012 Volume 84(Issue 12) pp:5392
Publication Date(Web):May 24, 2012
DOI:10.1021/ac3009065
This work reports a novel electrochemical immunoassay protocol with signal amplification for determination of proteins (human IgG here used as a model target analyte) at an ultralow concentration using DNA-based hybridization chain reaction (HCR). The immuno-HCR assay consists of magnetic immunosensing probes, nanogold-labeled signal probes conjugated with the DNA initiator strands, and two different hairpin DNA molecules. The signal is amplified by the labeled ferrocene on the hairpin probes. In the presence of target IgG, the sandwiched immunocomplex can be formed between the immobilized antibodies on the magnetic beads and the signal antibodies on the gold nanoparticles. The carried DNA initiator strands open the hairpin DNA structures in sequence and propagate a chain reaction of hybridization events between two alternating hairpins to form a nicked double-helix. Numerous ferrocene molecules are formed on the neighboring probe, each of which produces an electrochemical signal within the applied potentials. Under optimal conditions, the immuno-HCR assay presents good electrochemical responses for determination of target IgG at a concentration as low as 0.1 fg mL–1. Importantly, the methodology can be further extended to the detection of other proteins or biomarkers.
Co-reporter:Bing Zhang, Dianping Tang, Bingqian Liu, Yuling Cui, Huafeng Chen, Guonan Chen
Analytica Chimica Acta 2012 Volume 711() pp:17-23
Publication Date(Web):20 January 2012
DOI:10.1016/j.aca.2011.10.049
A new electrochemical immunosensor for sensitive determination of thyroid-stimulating hormone (TSH) was designed by using redox-active nanogold-functionalized magnetic beads (GoldMag) as signal tags on the nanogold–graphene interface. To construct such GoldMag nanostructures, polyethyleneimine-functionalized magnetic beads (PEI-MBs) were initially prepared by using a wet chemical method, and the electroactive thionine molecules and gold nanoparticles were then alternately immobilized on the surface of PEI-MBs by using an opposite-charged adsorption technique and an in situ synthesis method, respectively. The synthesized GoldMag nanostructures were utilized as signal tags for the label of horseradish peroxidase-anti-TSH conjugates (HRP-anti-TSH). With a sandwich-type immunoassay format, the conjugated signal tags on the transducer were increased with the increasing TSH concentration in the sample, thus enhancing the signal of the electrochemical immunosensor due to the labeled HRP toward the catalytic reduction of H2O2. Under optimal conditions, the current was proportional to the logarithm of TSH concentration ranging from 0.01 to 20 μIU mL−1 in pH 6.0 HAc–NaAc containing 6 mM H2O2. The detection limit (LOD) was 0.005 μIU mL−1 TSH at 3sB. The immunosensor displayed an acceptable reproducibility, stability and selectivity. In addition, the methodology was evaluated with human serum specimens, receiving good correlation with results from commercially available electrochemiluminescent analyzer.Graphical abstractHighlights► We designed an electrochemical immunoassay of thyroid-stimulating hormone with signal amplification. ► A new signal tag with biofunctionalized organic–inorganic GoldMag nanostructures. ► A well-dispersive gold nanoparticles on graphene nanosheets. ► Redox-active GoldMag nanolabels.
Co-reporter:Jun Zhou, Dianping Tang, Li Hou, Yuling Cui, Huafeng Chen, Guonan Chen
Analytica Chimica Acta 2012 Volume 751() pp:52-58
Publication Date(Web):2 November 2012
DOI:10.1016/j.aca.2012.09.004
Here we designed a new electrochemical immunoassay protocol for determination of carcinoembryonic antigen (CEA) using nanoplatinum-enclosed gold nanocores (Pt@Au) as catalytically promoted nanolabels on the carbon nanospheres and graphene-modified immunosensor. The Pt@Au nanolabels were synthesized and functionalized with monoclonal anti-CEA antibodies and glucose oxidase (GOx). Using the functional Pt@Au nanolabels as molecular tags, the assay was implemented relative to glucose–hydroquinone system with a sandwich-type immunoassay. Initially, the added glucose was oxidized to gluconolactone and H2O2 by the labeled GOx, and then the generated H2O2 was reduced with the help of platinum nanoparticles, leading to the production of oxygen. The self-produced oxygen could promote the re-oxidation of the glucose, thus resulting in the dual amplification of the electrochemical signal. Several nanolabels, such as multiarmed star-like platinum nanowires, hollow platinum nanospheres and Pt@Au nanostructures, were investigated for CEA detection and improved analytical features were obtained with the Pt@Au nanostructures. Under optimal conditions, the Pt@Au-based immunoassay displayed a wide working range from 0.001 to 120 ng mL−1 with a low detection limit of 0.5 pg mL−1 CEA at 3sB. Intra- and inter-assay coefficients of variation were <10.9%. The system was evaluated with 10 clinical serum samples, receiving good accordance with results from enzyme-linked immunosorbent assay method.Graphical abstractHighlights► We report a new sandwich-type electrochemical immunoassay of biomarkers. ► Nanoplatinum-enclosed gold nanocores as catalytically promoted nanolabels. ► Dual amplification of electrochemical signal. ► The catalytic reaction of the products.
Co-reporter:Yuling Cui, Huafeng Chen, Li Hou, Bing Zhang, Bingqian Liu, Guonan Chen, Dianping Tang
Analytica Chimica Acta 2012 Volume 738() pp:76-84
Publication Date(Web):13 August 2012
DOI:10.1016/j.aca.2012.06.013
Methods based on nanomaterial labels have been developed for electrochemical immunosensors and immunoassays, but most involved low sensitivity. Herein a novel class of molecular tags, nanogold–polyaniline–nanogold microspheres (GPGs), was first synthesized and functionalized with horseradish peroxidase-conjugated thyroid-stimulating hormone antibody (HRP-Ab2) for sensitive electrochemical immunoassay of thyroid-stimulating hormone (TSH). X-ray diffraction, confocal Raman spectroscopy, scanning electron microscope and transmission electron microscope were employed to characterize the prepared GPGs. Based on a sandwich-type immunoassay format, the assay was performed in pH 5.0 acetate buffer containing 6.0 mmol L−1 H2O2 by using GPG-labeled HRP-Ab2 as molecular tags. Compared with pure polyaniline nanospheres and gold nanoparticles alone, the GPG hybrid nanostructures increased the surface area of the nanomaterials, and enhanced the immobilized amount of HRP-Ab2. Several labeling protocols comprising HRP-Ab2, nanogold particle-labeled HRP-Ab2, and polyaniline nanospheres-labeled HRP-Ab2, were also investigated for determination of TSH and improved analytical features were obtained by using the GPG-labeled HRP-Ab2. With the GPG labeling method, the effects of incubation time and pH of acetate buffer on the current responses of the immunosensors were also studied. The strong attachment of HRP-Ab2 to the GPGs resulted in a good repeatability and intermediate precision down to 7%. The dynamic concentration range spanned from 0.01 to 20 μIU mL−1 with a detection limit (LOD) of 0.005 μIU mL−1 TSH at the 3sB criterion. Significantly, no significant differences at the 0.05 significance level were encountered in the analysis of 15 spiking serum samples between the developed electrochemical immunoassay and the commercially available enzyme-linked immunosorbent assay (ELISA) method for determination of TSH.Graphical abstract.Highlights► A novel immunosensing strategy was designed for detection of thyroid-stimulating hormone. ► Using nanogold–polyaniline–nanogold microspheres as molecular tags. ► Improvement of electrochemical activity of nanolabels. ► Combination enzyme labels with nanolabels for signal amplification.
Co-reporter:Huafeng Chen, Yuling Cui, Bing Zhang, Bingqian Liu, Guonan Chen, Dianping Tang
Analytica Chimica Acta 2012 Volume 728() pp:18-25
Publication Date(Web):30 May 2012
DOI:10.1016/j.aca.2012.03.052
A novel class of redox-active molecular tags, poly(o-phenylenediamine)-carried nanogold particles (GPPDs), was first synthesized and functionalized with horseradish peroxidase-anti-prolactin conjugates (HRP-anti-PRL). Thereafter, a specific sandwich-type electrochemical immunoassay was designed for determination of prolactin (PRL) by using GPPD-labeled HRP-anti-PRL conjugates as molecular tags on anti-PRL antibody-modified glassy carbon electrode. Compared with pure gold nanoparticles and poly(o-phenylenediamine) microspheres, the as-prepared GPPDs increased the surface coverage of the nanostructures, and enhanced the immobilization amount of biomolecules. Several labeling protocols compromising GPPD-labeled HRP-anti-PRL, nanogold particles-labeled HRP-anti-PRL and poly(o-phenylenediamine) microspheres-labeled HRP-anti-PRL, were investigated for detection of PRL, and improved analytical features were obtained with the GPPD-based strategy. With the GPPD labeling method, dependence of the electrochemical signals on the incubation time and pH of the assay solution were also studied. The strong attachment of HRP-anti-PRL to the GPPDs resulted in a good repeatability and intermediate reproducibility down to 9.8%. The dynamic concentration range spanned from 0.5 to 180 ng mL−1 PRL with a detection limit of 0.1 ng mL−1 at the 3Sblank level. No significant differences at the 95% confidence level were encountered in the analysis of 10 spiked blank cattle serum samples between the developed immunoassay and enzyme-linked immunosorbent assay method for determination of PRL.Graphical abstractHighlights► This work designs a sensitive and feasible sandwich-type electrochemical immunoassay system for determination of prolactin. ► A novel class of redox-active molecular tags, poly(o-phenylenediamine)-carried nanogold particles. ► A lower detection limit of the electrochemical immunosensor than that of commercially available ELISAs.
Co-reporter:Wenqiang Lai, Dianping Tang, Xiaohua Que, Junyang Zhuang, Libing Fu, Guonan Chen
Analytica Chimica Acta 2012 Volume 755() pp:62-68
Publication Date(Web):28 November 2012
DOI:10.1016/j.aca.2012.10.028
A new and disposable electrochemical immunosensor was designed for detection of alpha-fetoprotein (AFP), as a model analyte, with sensitivity enhancement based on enzyme-catalyzed silver deposition onto irregular-shaped gold nanoparticles (ISGNPs). The assay was carried out with a sandwich-type immunoassay protocol by using ISGNP-labeled anti-AFP antibodies conjugated with alkaline phosphatase (ALP–Ab2) as detection antibodies. The enzymatically catalytic deposition of silver on the electrode could be measured by stripping analysis in KCl solution due to the Ag/AgCl solid-state voltammetric process. Several labeling protocols including spherical gold nanoparticle-labeled ALP–Ab2 and ISGNP-labeled ALP–Ab2 were investigated for determination of AFP, and improved analytical properties were achieved with the ISGNP labeling. With the ISGNP labeling method, the effects of incubation time and incubation temperature for antigen-antibody reaction, and deposition time of silver on the current responses of the electrochemical immunosensors were also monitored. Under optimal conditions, the electrochemical immunosensor exhibited a wide dynamic range from 0.01 ng mL−1 to 200 ng mL−1 with a detection limit of 5.0 pg mL−1 AFP. The immunosensor displayed a good stability and acceptable reproducibility and accuracy. No significant differences at the 95% confidence level were encountered in the analysis of 10 clinical serum samples between the developed immunoassay and the commercially available electrochemiluminescent method for determination of AFP.Graphical abstractHighlights► We report a new sandwich-type electrochemical immunoassay of biomarkers. ► Enzyme-catalyzed silver deposition. ► Irregular-shaped gold nanoparticles. ► Nanosilver molecular tags.
Co-reporter:Yuling Cui, Dianping Tang, Bingqian Liu, Huafeng Chen, Bing Zhang and Guonan Chen
Analyst 2012 vol. 137(Issue 7) pp:1656-1662
Publication Date(Web):22 Feb 2012
DOI:10.1039/C2AN15848E
Multi-armed dendritic polyaniline nanofibers (MPANFs) were first synthesized and functionalized with horseradish peroxidase (HRP) and carcinoembryonic antibody (anti-CEA) for highly efficient electrochemical immunoassay of carcinoembryonic antigen (CEA, as a model analyte here) in this work. Transmission electron microscope (TEM) and scanning electron microscope (SEM) techniques were employed to characterize the synthesized MPANFs. By using anti-CEA-conjugated core–shell gold–Fe3O4 nanocomposites (GoldMag) as immunosensing probes and biofunctionalized MPANFs as molecular tags, a new sandwich-type homogeneous immunoassay strategy was developed for the determination of CEA by coupling with a home-made flow-through magneto-controlled microfluidic device. Under optimal conditions, the electrochemical immunoassay exhibited a wide dynamic range of four orders of magnitude from 1.0 pg mL−1 to 50 ng mL−1 with a low detection limit of 0.1 pg mL−1 CEA at 3σ. Intra- and inter-assay coefficients of variation were below 10%. The assayed results for clinical serum specimens with the electrochemical immunoassay were received in good accordance with the results obtained from the referenced enzyme-linked immunosorbent assay (ELISA) method.
Co-reporter:Libing Fu, Junyang Zhuang, Dianping Tang, Xiaohua Que, Wenqiang Lai and Guonan Chen
Analyst 2012 vol. 137(Issue 19) pp:4425-4427
Publication Date(Web):25 Jul 2012
DOI:10.1039/C2AN35662G
A novel, simple, signal-enhanced electrochemical sensor was designed for sensitive and selective determination of mercury ions by using target-triggered conformational change of DNA pseudoknots with the assistance of auxiliary DNA strands.
Co-reporter:Bing Zhang, Li Hou, Dianping Tang, Bingqian Liu, Jianrong Li, and Guonan Chen
Journal of Agricultural and Food Chemistry 2012 Volume 60(Issue 36) pp:8974-8982
Publication Date(Web):August 20, 2012
DOI:10.1021/jf302051k
Marine toxins from microscopic algae can accumulate through the food chain and cause various neurological and gastrointestinal illnesses for human health. Herein, we designed a new ultrasensitive multiplexed immunoassay protocol for simultaneous electrochemical determination of brevetoxin B (BTX-2) and dinophysistoxin-1 (DTX-1) in seafood using distinguishable metal nanocluster-labeled molecular tags as traces on bifunctionalized magnetic capture probes. To construct such a bifunctionalized probe, monoclonal mouse anti-BTX-2 (mAb1) and anti-DTX-1 (mAb2) antibodies were co-immobilized on a magnetic bead (MB–mAb1,2). The distinguishable metal nanoclusters including cadmium nanoclusters (CdNC) and copper nanoclusters (CuNC) were synthesized using the artificial peptides with amino acid sequence CCCYYY, which were used as distinguishable signal tags for the label of the corresponding bovine serum albumin–BTX-2 and bovine serum albumin–DTX-1 conjugates. A competitive-type immunoassay format was adopted for the online simultaneous monitoring of BTX-2 and DTX-1 on a homemade flow-through magnetic detection cell. The assay was based on the stripping voltammetric behaviors of the labeled CdNC and CuNC at the various peak potentials in pH 2.5 HCl containing 0.01 M KCl using square wave anodic stripping voltammetry (SWASV). Under optimal conditions, the multiplexed immunoassays enabled simultaneous detection of BTX-2 and DTX-1 in a single run with wide working ranges of 0.005–5 ng mL–1 for two marine toxins. The limit of detection (LOD) and limit of quantification (LOQ) were 1.8 and 6.0 pg mL–1 for BTX-2, while those for DTX-1 were 2.2 and 7.3 pg mL–1, respectively. No non-specific adsorption and electrochemical cross-talk between neighboring sites were observed during a series of procedures to detect target analytes. The covalent conjugation of biomolecules onto the nanoclusters and magnetic beads resulted in good repeatability and intermediate precision down to 9.5%. The method featured unbiased identification of negative (blank) and positive samples. No significant differences at the 0.05 significance level were encountered in the analysis of 12 spiked samples, including Sinonovacula constricta, Musculista senhousia, and Tegillarca granosa, between the multiplexed immunoassay and commercially available enzyme-linked immunosorbent assay (ELISA) for analysis of BTX-2 and DTX-1.
Co-reporter:Juan Tang, Li Hou, Dianping Tang, Jun Zhou, Zhouping Wang, Jianrong Li, Guonan Chen
Biosensors and Bioelectronics 2012 Volume 38(Issue 1) pp:86-93
Publication Date(Web):October–December 2012
DOI:10.1016/j.bios.2012.05.006
A facile and feasible magneto-controlled immunosensing platform was designed for sensitive electrochemical immunoassay of brevetoxin B (BTX-2) in seafood by using guanine-assembled graphene nanoribbons (GGNRs) as molecular tags on a home-made magnetic carbon paste electrode. Initially, monoclonal mouse anti-BTX-2 antibodies were covalently immobilized on the surface of magnetic beads, which were used as the immunosensing probes for the capture of BTX-2. The recognition elements were prepared by chemical modification of bovine serum albumin-BTX-2 conjugates (BTX-2-BSA) with the GGNRs. Based on a competitive-type immunoassay format, the formed magnetic immunocomplex was integrated on the electrode with an external magnet, followed by determination in pH 6.5 phosphate-buffered solution containing 2 μM Ru(bpy)3Cl2. Under optimal conditions, the electrochemical signals decreased with the increasing BTX-2 concentrations in the sample. The dynamic concentration range spanned from 1.0 pg mL−1 to 10 ng mL−1 with a detection limit of 1.0 pg mL−1 BTX-2. Inter- and intra-batch assay precisions were substantially improved by resorting to the GGNR manifold. The method featured unbiased identification of negative (blank) and positive samples. No significant differences at the 95% confidence level were encountered in the analysis of 12 spiked samples including S. constricta, M. senhousia and T. granosa between the electrochemical immunoassay and commercially available enzyme-linked immunosorbent assay (ELISA) for determination of BTX-2.Highlights► We devise a magneto-controlled immunosensor for electrochemical detection of brevetoxin B. ► Antibody-functionalized magnetic beads as immunosensing probes. ► Biomolecules-functionalized graphene nanoribbons assembled guanine as molecular tags. ► Analysis of real samples and evaluation of method trueness.
Co-reporter:Juan Tang, Dianping Tang, Reinhard Niessner, Dietmar Knopp, Guonan Chen
Analytica Chimica Acta 2012 720() pp: 1-8
Publication Date(Web):
DOI:10.1016/j.aca.2011.12.070
Co-reporter:Huafeng Chen, Dianping Tang, Bing Zhang, Bingqian Liu, Yuling Cui, Guonan Chen
Talanta 2012 Volume 91() pp:95-102
Publication Date(Web):15 March 2012
DOI:10.1016/j.talanta.2012.01.025
Co-reporter:Jun Zhou, Junyang Zhuang, Manuel Miró, Zhuangqian Gao, Guonan Chen, Dianping Tang
Biosensors and Bioelectronics 2012 Volume 35(Issue 1) pp:394-400
Publication Date(Web):15 May 2012
DOI:10.1016/j.bios.2012.03.025
Two nanostructures including carbon nanospheres-graphene hybrid nanosheets (CNS-GNS) and hollow platinum nanospheres (HPtNS) were first synthesized by using direct electrolytic reduction and wet chemistry methods, respectively. Thereafter, a specific sandwich-type electrochemical immunoassay was designed for determination of carcinoembryonic antigen (CEA) by using HPtNS-labeled horseradish peroxidase-anti-CEA conjugates (HRP-anti-CEA) as molecular tags and anti-CEA-assembled CNS-GPS as sensing probes. Compared with pure graphene nanosheets, the presence of carbon nanospheres on the graphene increased the surface coverage of the substrate, and enhanced the immobilized amount of primary antibodies. Several labeling protocols, such as HRP-anti-CEA, solid platinum nanoparticle-labeled HRP-anti-CEA, and hollow platinum nanospheres-labeled HRP-anti-CEA, were investigated for determination of CEA and improved analytical features were obtained with hollow platinum nanosphere labeling. With the HPtNS labeling method, the effects of incubation time and pH on the current responses of the immunosensors were also studied. The strong attachment of biomolecules to the CNS-GPS and HPtNS resulted in a good repeatability and intermediate precision down to 10.2%. The dynamic concentration range spanned from 0.001 ng mL−1 to 100 ng mL−1 CEA with a detection limit of 1.0 pg mL−1 at the 3Sblank level. No significant differences at the 0.05 significance level were encountered in the analysis of 10 clinical serum samples between the developed immunoassay and the commercially available electrochemiluminescent method for determination of CEA.Highlights► We introduce a new electrochemical immunoassay protocol for sensitive detection of cancer markers. ► Carbon nanospheres-graphene hybrid nanosheets as matrices. ► Hollow platinum nanolabels.
Co-reporter:Bing Zhang, Yuling Cui, Bingqian Liu, Huafeng Chen, Guonan Chen, Dianping Tang
Biosensors and Bioelectronics 2012 Volume 35(Issue 1) pp:461-465
Publication Date(Web):15 May 2012
DOI:10.1016/j.bios.2012.02.051
A novel class of molecular tags, cadmium ion-doped magnetic poly(styrene-acrylic acid) nanospheres (Cd-MPSA), was first synthesized and functionalized with polyclonal rabbit anti-human luteinizing hormone antibodies (PAb2) for highly efficient electrochemical immunoassay of luteinizing hormone (LH). Transmission electron microscope (TEM) and Fourier transform infrared spectroscope (FTIR) were employed to characterize the prepared Cd-MPSA. By using Cd-MPSA-labeled PAb2 as molecular tags, a novel sandwich-type immunoassay protocol was built for determination of LH on monoclonal mouse anti-human luteinizing hormone antibody (MAb1)-functionalized gold electrode. The assay was carried out in pH 5.3 HAc-NaAc buffer solution by square wave voltammetry (SWV). The signal was obtained by the reduction of the doped cadmium ions in the Cd-MPSA. Under optimal conditions, the currents increased with the increasing LH level in the sample, and exhibited a linear range from 0.25 to 240 mIU mL−1 with a detection limit of 0.08 mIU mL−1 LH at 3sB. The precision, reproducibility, and specificity were acceptable. No obvious difference was encountered in the analysis of spiking LH samples into newborn calf serum with the referenced values.Highlights► Cadmium ion-doped magnetic poly(styrene-acrylic acid) nanospheres as molecular tags. ► Enzyme-free electrochemical immunoassay. ► Mediator-free sandwich-type immunoassay. ► Amplification of electrochemical signal and noise reduction.
Co-reporter:Bingqian Liu, Qunfang Li, Bing Zhang, Yuling Cui, Huafeng Chen, Guonan Chen and Dianping Tang
Nanoscale 2011 vol. 3(Issue 5) pp:2220-2226
Publication Date(Web):04 Apr 2011
DOI:10.1039/C1NR10069F
Herein, we describe a facile and feasible synthesis method for patterning nanogold particles onto magnetic mesoporous CoFe2O4 nanostructures (Au-MMNs) by using poly(vinyl pyrrolidone) (PVP) as cross-linker. Initially, mesoporous CoFe2O4 nanoparticles were initially synthesized with a thermal decomposition method by using mesoporous silica nanoparticles as templates, and then nanometre-sized gold particles were produced through the in situ reduction of the AuIII on the PVP-functionalized CoFe2O4. The as-prepared Au-MMNs were characterized by transmission electron microscopy (TEM), N2 adsorption-desorption isotherms, UV-visible adsorption spectrometer, vibrating sample magnetometer (VSM) and X-ray photoelectron spectroscopy (XPS). Furthermore, we also demonstrate the conjugation capacity of the synthesized Au-MMNs toward biomolecules by using quartz crystal microbalance (QCM), and the possible application in the electrochemical immunoassays. Experimental results indicated that the resulting Au-MMNs display good conjugation capability toward the biomolecules, and excellent analytical properties for determination of target molecules.
Co-reporter:Dianping Tang, Juan Tang, Biling Su, Qunfang Li and Guonan Chen
Chemical Communications 2011 vol. 47(Issue 33) pp:9477-9479
Publication Date(Web):22 Jul 2011
DOI:10.1039/C1CC13340C
A novel electrochemical method to detect hepatitis C virus was developed based on site-specific cleavage of BamHI endonuclease and enzymatic signal amplification with horseradish peroxidase-encapsulated nanogold hollow spheres.
Co-reporter:Qunfang Li, Lingxing Zeng, Jinchao Wang, Dianping Tang, Bingqian Liu, Guonan Chen, and Mingdeng Wei
ACS Applied Materials & Interfaces 2011 Volume 3(Issue 4) pp:1366
Publication Date(Web):March 30, 2011
DOI:10.1021/am200228k
This study demonstrates a facile and feasible strategy toward the development of advanced electrochemical immunosensors based on chemically functionalized magnetic mesoporous organic−inorganic hybrid nanomaterials, and the preparation, characterization, and measurement of relevant properties of the immunosensor for detection of carcinoembryonic antigen (CEA, as a model analyte) in clinical immunoassays. The as-prepared nanomaterials composed of a magnetic mesoporous NiCo2O4 nanosheet, an interlayer of Nafion/thionine organic molecules and a nanogold layer show good adsorption properties for the attachment of horseradish peroxidase-labeled secondary anti-CEA antibody (HRP-anti-CEA). With a sandwich-type immunoassay format, the functional bionanomaterials present good analytical properties to facilitate and modulate the way it was integrated onto the electrochemical immunosensors, and allows the detection of CEA at a concentration as low as 0.5 pg/mL. Significantly, the immunosensor could be easily regenerated by only using an external magnet without the need of any dissociated reagents. Importantly, the as-synthesized magnetic mesoporous NiCo2O4 nanomaterials could be further extended for detection of other biomarkers or biocompounds.Keywords: carcinoembryonic antigen; electrochemical immunosensor; magnetic organic−inorganic hybrid nanomaterials; mesoporous NiCo2O4 nanosheets
Co-reporter:Bingqian Liu, Bing Zhang, Yuling Cui, Huafeng Chen, Zhuangqiang Gao, and Dianping Tang
ACS Applied Materials & Interfaces 2011 Volume 3(Issue 12) pp:4668
Publication Date(Web):November 7, 2011
DOI:10.1021/am201087r
A facile and simple electrochemical immunoassay for ultrasensitive determination of streptomycin residues (STR) in food was designed by using nanogold-assembled mesoporous silica (GMSNs) as bionanolabels on a three-dimensional redox-active organosilica-functionalized sensing interface. To construct such a sensing interface, we initially synthesized organosilica colloids by using wet chemical method, and then utilized the prepared colloidal organosilica nanocomposites for the immobilization of monoclonal anti-STR antibodies on a glassy carbon electrode based on a sol–gel method. The bionanolabels were prepared based on coimmobilization of horseradish peroxidase (HRP) and STR-bovine serum albumin conjugates (STR-BSA) on the GMSNs. With a competitive-type immunoassay format, the assay toward STR analyte was carried out in pH 5.5 acetate acid buffer (ABS) by using redox-active organosilica nanocomposites as electron mediators, biofunctionalized GMSNs as traces, and hydrogen peroxide (H2O2) as enzyme substrate. Under optimal conditions, the reduction current of the electrochemical immunosensor decreased with the increase in STR level in the sample, and displayed a wide dynamic range of 0.05–50 ng mL–1 with a low detection limit (LOD) of 5 pg mL–1 at 3sB. Intra- and interassay coefficients of variation were less than 8.7 and 9.3% for STR detection, respectively. In addition, the methodology was validated with STR spiked samples including honey, milk, kidney, and muscle, receiving a good correspondence with the results obtained from high-performance liquid chromatography (HPLC).Keywords: electrochemical immunoassay; food; immune-biosensor; streptomycin residues;
Co-reporter:Juan Tang, Dianping Tang, Reinhard Niessner, Guonan Chen, and Dietmar Knopp
Analytical Chemistry 2011 Volume 83(Issue 13) pp:5407
Publication Date(Web):June 3, 2011
DOI:10.1021/ac200969w
A novel flow-through multiplexed immunoassay protocol for simultaneous electrochemical determination of carcinoembryonic (CEA) and alpha-fetoprotein (AFP) in biological fluids was designed using biofunctionalized magnetic graphene nanosheets (MGO) as immunosensing probes and multifunctional nanogold hollow microspheres (GHS) as distinguishable signal tags. The probes were fabricated by means of co-immobilization of primary anti-CEA (Ab1) and anti-AFP (Ab2) antibodies on the Fe3O4 nanoparticle-coated graphene nanosheets (MGO-Ab1,2). The reverse-micelle method was used for the synthesis of distinguishable signal tags by encapsulation of horseradish peroxide (HRP)-thionine and HRP-ferrocene into nanogold hollow microspheres, respectively, which were utilized as labels of the corresponding GHS-Ab1 and GHS-Ab2. A sandwich-type immunoassay format was employed for the online detection of CEA and AFP by coupling a flow-through detection cell with an external magnet. The assay was based on the catalytic reduction of H2O2 at the various peak potentials in the presence of the corresponding mediators. Experimental results revealed that the multiplexed electrochemical immunoassay enabled the simultaneous monitoring of AFP and CEA in a single run with wide working ranges of 0.01–200 ng mL–1 for AFP and 0.01–80 ng mL–1 for CEA. The detection limits (LODs) for both analytes at 1.0 pg mL–1 (at 3sB) were very low. No obvious nonspecific adsorption and cross-talk were observed during a series of analyses to detect target analytes. Intraassay and interassay coefficients of variation were <10%. Importantly, the methodology was evaluated for the analysis of clinical serum specimens, receiving a good correlation between the flow-through multiplexed electrochemical immunoassay and an electrochemiluminescence method as a reference.
Co-reporter:Dianping Tang, Juan Tang, Qunfang Li, Biling Su, and Guonan Chen
Analytical Chemistry 2011 Volume 83(Issue 19) pp:7255
Publication Date(Web):August 30, 2011
DOI:10.1021/ac201891w
This work reports an aptamer-based, disposable, and multiplexed sensing platform for simultaneous electrochemical determination of small molecules, employing adenosine triphosphate (ATP) and cocaine as the model target analytes. The multiplexed sensing strategy is based on target-induced release of distinguishable redox tag-conjugated aptamers from a magnetic graphene platform. The electronic signal of the aptasensors could be further amplified by coupling DNase I with catalytic recycling of self-produced reactants. The assay was based on the change in the current at the various peak potentials in the presence of the corresponding signal tags. Experimental results revealed that the multiplexed electrochemical aptasensor enabled the simultaneous monitoring of ATP and cocaine in a single run with wide working ranges and low detection limits (LODs: 0.1 pM for ATP and 1.5 pM for cocaine). This concept offers promise for rapid, simple, and cost-effective analysis of biological samples.
Co-reporter:Juan Tang, Dianping Tang, Biling Su, Qunfang Li, Bing Qiu, Guonan Chen
Electrochimica Acta 2011 Volume 56(Issue 24) pp:8168-8175
Publication Date(Web):1 October 2011
DOI:10.1016/j.electacta.2011.05.128
A facile and sensitive mediator-free electrochemical immunoassay was developed for determination of alpha-fetoprotein (AFP) in human serum with a sandwich-type mode by using silver nanowire–graphene hybrid nanocomposites (AgNW–GPs) as label. One-pot hydrothermal method was used for the synthesis of the AgNW–GPs with the aid of trisodium citrate. The as-prepared AgNW–GP was not only utilized for the label of horseradish peroxidase-conjugated anti-AFP (HRP-anti-AFP) with highly loading capacity, but also displayed good electrochemical behaviors. Compared with the conventional HRP-anti-AFP-based electrochemical immunoassay, the sensitivity of the proposed immunoassay by using the synthesized nanolabels was greatly improved. Under optimal conditions, the electrochemical immunosensor exhibited a wide linear range of 0.05–400 ng/mL with a low detection limit (LOD) of 5 pg/mL AFP (at 3sB). Intra- and inter-assay coefficients of variation were below 10% and 8.5%, respectively. The selectivity and stability of the immunosensor were acceptable. In addition, the methodology was also validated by assaying 16 positive serum samples and 7 negative serum samples, receiving a good correlation with the results obtained from the referenced electrochemiluminescence method.Highlights► We design a facile and sensitive mediator-free electrochemical immunoassay of biomarkers. ► Silver nanowires–graphene hybrid nanocomposites as labels. ► Hybrid graphene nanosheets with redox activity. ► In situ electrodeposited nanogold-chitosan membrane. ► Screening of real samples and intralaboratory validation.
Co-reporter:Juan Tang, Dianping Tang, Biling Su, Qunfang Li, Bin Qiu, Guonan Chen
Electrochimica Acta 2011 Volume 56(Issue 11) pp:3773-3780
Publication Date(Web):15 April 2011
DOI:10.1016/j.electacta.2011.02.059
A facile and sensitive mediator-free electrochemical immunosensor for detection of alpha-fetoprotein (AFP) was designed by using nanosilver-coated silica nanoparticles (Ag-SiO2) as bionanolabels. To construct such an electrochemical immunosensor, silver ions/single-stranded DNA/graphene nanosheets were initially immobilized on a gold electrode in turn, then silver ions were in situ reduced to silver nanoparticles with the aid of NaBH4, and anti-AFP antibodies conjugated to silver nanoparticles were used. In the presence of AFP analyte, the sandwiched immunocomplex was formed on the electrode surface by using horseradish peroxidase-anti-AFP conjugate-labeled Ag-SiO2 (HRP-anti-AFP-Ag-SiO2) as secondary antibodies. Compared with pure silver nanoparticles, Ag-SiO2 nanocomposites could provide a large room for the immobilization of HRP-anti-AFP, and improve the electrochemical responses of the immunosensor. Meanwhile, the presence of highly conductive graphene nanosheets and silver nanoparticles provided a good pathway for electron transfer. Under optimal conditions, the immunosensor exhibited good electrochemical responses toward AFP ranging from 0.3 to 200 ng/mL with a detection limit (LOD) of 0.05 ng/mL (at 3σ) in pH 6.0 PBS-H2O2 system. Intra- and inter-assay displayed good precisions with coefficient of variation below 9.5%. In addition, the method was evaluated with 23 clinical serum samples, receiving good correlation with results from commercially available electrochemiluminescent analyzer.Research highlights► We fabricate a polyion graphene complex membrane-based immunosensing platform for sensitive electrochemical immunoassay of alpha-fetoprotein. ► Nanosilver-coated silica nanocomposites as bionanolabels. ► Graphene nanosheets, single-stranded DNA and silver nanoparticles as matrices. ► Direct electron transfer without electron mediator. ► Analysis of real samples and method comparison.
Co-reporter:Dianping Tang, Qunfang Li, Juan Tang, Biling Su, Guonan Chen
Analytica Chimica Acta 2011 Volume 686(1–2) pp:144-149
Publication Date(Web):7 February 2011
DOI:10.1016/j.aca.2010.11.054
A sensitive and facile quartz crystal microbalance (QCM) biosensor for glucose detection in biological fluids was developed by means of a displacement-type assay mode between glucose and its analogy dextran for concanavalin A (ConA) binding sites on a graphene-based sensing platform. To construct such a displacement-based sensor, phenoxy-derived dextran (DexP) molecules were initially assembled onto the surface of graphene-coated QCM probe via π–π stacking interaction, and ConA molecules were then immobilized on the dextran through the dextran-ConA interaction. Upon addition of glucose, the analyte competed with the dextran for the ConA, and displaced it from the QCM probe, leading to a change in the frequency. Under optimal conditions, the frequency change relative to the basic resonant frequency was proportional to glucose concentration, and exhibited a dynamic range from 0.01 to 7.5 mM with a low detection limit (LOD) of 5.0 μM glucose (at 3σ). The relative standard deviations (RSDs) were below 6.2% and 9.0% for the reproducibility and selectivity of the QCM glucose sensors, respectively. In addition, the assay system was evaluated with glucose spiking samples into the distilled water and blank cattle serum, receiving in excellent correlation with the referenced values.
Co-reporter:Juan Tang, Dianping Tang, Qunfang Li, Biling Su, Bin Qiu, Guonan Chen
Analytica Chimica Acta 2011 Volume 697(1–2) pp:16-22
Publication Date(Web):4 July 2011
DOI:10.1016/j.aca.2011.04.022
A new dual-amplification strategy of electrochemical signal based on the catalytic recycling of the product was developed for the antigen–antibody interaction by glucose oxidase (GOD)- conjugated gold–silver hollow microspheres (AuAgHSs) coupled with an artificial catalase, Prussian blue nanoparticles (PB), on a graphene-based immunosensing platform. The first signal amplification introduced in this study was based on the labeled GOD on the AuAgHSs toward the catalytic oxidation of glucose. The generated H2O2 was catalytically reduced by the immobilized PB on the graphene nanosheets with the second amplification. With a sandwich-type immunoassay format, carcinoembryonic antigen (CEA) was monitored as a model analyte by using the synthesized AuAgHSs as labels in pH 6.0 phosphate buffer containing 10 mM glucose. Under optimal conditions, the electrochemical immunosensor exhibited a wide dynamic range of 0.005–50 ng mL−1 with a low detection limit (LOD) of 1.0 pg mL−1 CEA (at 3σ). Both the intra- and inter-assay coefficients of variation (CVs) were lower than 10%. The specificity and stability of the immunosensor were acceptable. In addition, the assay was evaluated for clinical serum specimens, and received a good correlation with those obtained by the referenced electrochemiluminescent (ECL).Graphical abstractA new dual-amplification strategy of electrochemical signal based on the catalytic recycling of the product was developed for the antigen–antibody interaction by glucose oxidase-conjugated gold–silver hollow microspheres coupled with an artificial catalase, Prussian blue nanoparticles, on a graphene-based immunosensing platform.Highlights► We designed an electrochemical immunoassay of carcinoembryonic antigen with signal dual-amplification. ► A new signal tag with glucose oxidase-conjugated gold–silver hollow microspheres. ► An artificial catalase, Prussian blue nanoparticles, on a graphene-based sensing platform. ► Comparative study of the electrochemical immunoassay by using various signal tags and sensing platforms.
Co-reporter:Biling Su, Dianping Tang, Qunfang Li, Juan Tang, Guonan Chen
Analytica Chimica Acta 2011 Volume 692(1–2) pp:116-124
Publication Date(Web):29 April 2011
DOI:10.1016/j.aca.2011.02.061
A new sandwich-type electrochemical immunosensor with enhanced sensitivity was developed for detection of alpha-fetoprotein (AFP, as a model analyte) in biological fluids by using nanogold-enclosed titania nanoparticle (AuTi)-labeled secondary antibody on a gold–silver–graphene hybrid nanosheet (AuAgGP)-functionalized glassy carbon electrode (GCE). The presence of the AuAgGP nanosheets not only enhanced the immobilized amount of biomolecules, but also improved the electrochemical properties of the immunosensor. With the aid of AuTi nanolabels, the electrochemical signal was greatly amplified in comparison with pure nanogold or titania-based labels. Under optimal conditions, the sensitivity and dynamic range of the immunosensor were evaluated by using the labeled horseradish peroxidase on the AuTi as trace and H2O2 as enzyme substrate, and exhibited a wide dynamic range of 0.001–200 ng mL−1 with a low detection limit (LOD) of 0.5 pg mL−1 AFP (at 3σ). Both the intra- and inter-assay coefficients of variation were less than 10%. The current of the immunosensor at 13th day was as much as 90% of the initial current. In addition, the methodology was evaluated for 8 positive serum specimens obtained from hepatocarcinoma patients and 19 negative sera, and validated with the commercially available Roche 2010 Electrochemiluminescent (ECL) Automatic Analyzer. No significant differences at the 95% confidence level were encountered between two methods.
Co-reporter:Juan Tang, Dianping Tang, Biling Su, Qunfang Li, Bin Qiu and Guonan Chen
Analyst 2011 vol. 136(Issue 19) pp:3869-3871
Publication Date(Web):10 Aug 2011
DOI:10.1039/C1AN15443E
A simple and facile impedance immunoassay strategy for sensitive detection of alpha-fetoprotein (AFP), as a model cancer marker, was developed by using target-induced release of nanogold particle-labelled anti-AFP antibodies from polyvinylpyrrolidone-coated magnetic carbon nanotubes.
Co-reporter:Bingqian Liu, Dianping Tang, Juan Tang, Biling Su, Qunfang Li and Guonan Chen
Analyst 2011 vol. 136(Issue 11) pp:2218-2220
Publication Date(Web):07 Mar 2011
DOI:10.1039/C0AN00921K
A novel, enzyme-free amperometric immunoassay of biomarkers with sensitive enhancement was designed by using gold nanoflower-labeled detection antibodies toward the catalytic reduction of p-nitrophenol and redox cycling of p-aminophenol on a graphene-based Au(111) platform.
Co-reporter:Dianping Tang, Juan Tang, Qunfang Li, Bingqian Liu, Huanghao Yang and Guonan Chen
RSC Advances 2011 vol. 1(Issue 1) pp:40-43
Publication Date(Web):26 Jul 2011
DOI:10.1039/C1RA00114K
A novel magneto-controlled electrochemical sensing strategy for simple, sensitive and rapid determination of small molecules was designed by using target-induced release of ferrocene-labeled aptamers from a magnetic graphene platform.
Co-reporter:Biling Su, Dianping Tang, Juan Tang, Qunfang Li, Guonan Chen
Analytical Biochemistry 2011 Volume 417(Issue 1) pp:89-96
Publication Date(Web):1 October 2011
DOI:10.1016/j.ab.2011.06.001
A new electrochemical immunoassay of alpha-fetoprotein (AFP) was developed on an organic–inorganic hybrid nanostructure-functionalized carbon electrode by coupling with magnetic bionanolabels. Multi-walled carbon nanotubes (CNTs), single-stranded DNA, thionine and AFP were utilized for the construction of the immunosensor, while the core–shell Fe3O4-silver nanocomposites were employed for the label of horseradish peroxidase-anti-AFP conjugates (HRP-anti-AFP-AgFe). Electrochemical measurement toward AFP was carried out by using magnetic bionanolabels as traces and H2O2 as enzyme substrate with a competitive-type immunoassay mode. Experimental results indicated that the immunosensors with carbon nanotubes and DNA exhibited better electrochemical responses than those of without carbon nanotubes or DNA. Under optimal conditions, the electrochemical immunosensor by using HRP-anti-AFP-AgFe as signal antibodies exhibited a linear range of 0.001–200 ng mL−1 AFP with a low detection limit of 0.5 pg mL−1 at 3sB. Both intra- and inter-assay coefficients of variation were 7.3%, 9.4%, 8.7% and 10.2%, 7.8%, 9.4% toward 0.01, 30, 120 ng mL−1 AFP, respectively. The specificity and stability of the electrochemical immunoassay were acceptable. In addition, the methodology was validated for 12 clinical serum specimens including 9 positive specimens and 3 normal specimens, receiving a good correlation with the results obtained from the referenced electrochemiluminescence assay.
Co-reporter:Huafeng Chen, Bing Zhang, Yuling Cui, Bingqian Liu, Guonan Chen and Dianping Tang
Analytical Methods 2011 vol. 3(Issue 7) pp:1615-1621
Publication Date(Web):21 Jun 2011
DOI:10.1039/C1AY05172E
A rapid and sensitive one-step electrochemical immunoassay for the determination of α-fetoprotein (AFP, as a model biomarker) was developed by immobilizing anti-AFP antibody on a nanogold-functionalized graphene interface. Initially, thionine molecules as electron mediators were conjugated onto the surface of graphene nanosheets, then gold nanoparticles were sandwiched onto the graphene, and then horseradish peroxidase-anti-AFP (HRP-anti-AFP) conjugates were immobilized on the nanogold surface. The presence of two-dimensional graphene nanosheets with high conductivity not only increased the surface coverage of the electrode, but also enhanced the immobilized amount of biomolecules. With the AFP analyte, the formed antigen–antibody complex was coated on the electrode surface, which partially hindered the immobilized HRP toward the catalytic reduction of H2O2 in the solution. Under optimal conditions, the electrochemical immunosensor displayed a wide dynamic range of 0.1–200 ng mL−1 with a detection limit (LOD) of 0.05 ng mL−1 AFP at 3sB. The reproducibility, selectivity and stability of the immunosensor were investigated with the acceptable results. In addition, the one-step immunoassay was evaluated and validated by assaying 5 positive and 5 negative serum specimens, and the obtained results were compared with those by the referenced electrochemiluminescent, receiving a good correlation between the two methods.
Co-reporter:Biling Su, Dianping Tang, Juan Tang, Yuling Cui, Guonan Chen
Biosensors and Bioelectronics 2011 30(1) pp: 229-234
Publication Date(Web):
DOI:10.1016/j.bios.2011.09.017
Co-reporter:Dianping Tang, Juan Tang, Biling Su, Guonan Chen
Biosensors and Bioelectronics 2011 Volume 26(Issue 5) pp:2090-2096
Publication Date(Web):15 January 2011
DOI:10.1016/j.bios.2010.09.012
A sensitive electrochemical immunosensor for the fast screening of brevetoxin B (BTX-2) in food samples was developed by means of immobilizing BTX-2–bovine serum albumin conjugate (BTX-2–BSA) on the gold nanoparticles-decorated amine-terminated poly(amidoamine) dendrimers (AuNP–PAADs). The presence of gold nanoparticles greatly improved the conductivity of the PAADs, and three-dimensional PAADs increased the surface coverage of the biomolecules on the electrode. Under optimal conditions, three types of immunosensor, i.e. with AuNPs, PAADs, or AuNP–PAADs, were used for the determination of BTX-2 in a competitive-type immunoassay format using horseradish peroxidase-labeled anti-BTX antibodies (HRP–anti-BTX-2) as trace in the H2O2–o-phenylenediamine (o-PD) system. A low detection limit (LOD) of 0.01 ng/mL and a wide dynamic working linear range of 0.03–8 ng/mL BTX-2 using AuNP–PAADs as matrices were obtained in comparison with those of only using AuNP or PAADs. Intra-batch assay precision was substantially improved by resorting to the AuNP–PAADs manifold. The proposed method features unbiased identification of negative (blank) and positive samples. No significant differences were encountered in the analysis of the spiking real samples between the electrochemical immunosensor and liquid chromatography for the determination of BTX-2. Importantly, this method provided a biocompatible immobilization and a promising immunosensing platform for analytes with small molecules in the analysis and detection of food safety.
Co-reporter:Yuling Cui;Bing Zhang;Bingqian Liu;Huafeng Chen;Guonan Chen
Microchimica Acta 2011 Volume 174( Issue 1-2) pp:
Publication Date(Web):2011 July
DOI:10.1007/s00604-011-0608-1
We report on a new electrochemical biosensing strategy for the sensitive detection of hydrogen peroxide (H2O2) in foodstuff samples. It is based on a gold electrode modified with layer of graphene patterned with a multilayer made from an organic–inorganic hybrid nanomaterial. Initially, a layer of thionine (Th) was assembled on the surface of the graphene nanosheets, and these were then cast on the surface of the electrode for the alternate assembly of gold nanoparticles and horseradish peroxidase. The large surface-to-volume ratio and high conductivity of the nanosheets provides a benign microenvironment for the construction of the biosensor. The use of such a multilayer not only shortens the electron transfer pathway of the active center of the enzyme due to the presence of gold nanoparticles, but also enhances the electrocatalytic efficiency of the biosensor toward the reduction of H2O2. The electrochemical characteristics of the biosensor were studied by cyclic voltammetry and chronoamperometry. The number of layers, the operating potential, and the pH of the supporting electrolyte were optimized. Linear response is obtained for the range from 0.5 μM to 1.8 mM of H2O2, the detection limit is 10 nM (at S/N = 3), and 95% of the steady-state current is reached within 2 s. The method was applied to sense H2O2 in spiked sterilized milk and correlated excellently with the permanganate titration method.
Co-reporter:Bing Zhang, Dianping Tang, Bingqian Liu, Huafeng Chen, Yuling Cui, Guonan Chen
Biosensors and Bioelectronics 2011 Volume 28(Issue 1) pp:174-180
Publication Date(Web):15 October 2011
DOI:10.1016/j.bios.2011.07.016
A new flow-through electrochemical immunosensor was designed for sensitive detection of alpha-fetoprotein (AFP) in human serum by using nanogold-functionalized magnetic graphene nanosheets as immunosensing probes. Initially, amino functionalized magnetic beads were covalently immobilized on the surface of graphene oxide nanosheets (MGPs), then nanogold particles were adsorbed on the amino groups of the MGPs to construct GoldMag nanocomposites functionalized graphene nanosheets (GMGPs), and then horseradish peroxidase-anti-AFP conjugates (HRP-anti-AFP) were assembled onto the surface of nanogold particles (bio-GMGP). With the aid of an external magnet, the formed bio-GMGPs were attached onto the base electrode in the flow system. With a non-competitive immunoassay format, the injected sample containing AFP antigens was produced transparent immunoaffinity reaction with the immobilized HRP-anti-AFP on the bio-GMGPs. The formed immunocomplex inhibited partly the active center of HRP, and decreased the labeled HRP toward the reduction of H2O2. The performance and factors influencing the performance of the immunosensor were investigated in detail. Under optimal conditions, the electrochemical immunosensor displayed a wide working range of 0.01–200 ng mL−1 with a low detection limit (LOD) of 1.0 pg mL−1 AFP (at 3sB). Intra- and inter-assay coefficients of variation (CV) were below 10%. In addition, the methodology was validated with real serum samples, receiving a good correlation with the results obtained from commercially available electrochemiluminescence automated analyzer.
Co-reporter:Qunfang Li, Dianping Tang, Juan Tang, Biling Su, Jianxin Huang, Guonan Chen
Talanta 2011 Volume 84(Issue 2) pp:538-546
Publication Date(Web):15 April 2011
DOI:10.1016/j.talanta.2011.01.063
A feasible and practicable amperometric immunoassay strategy for sensitive screening of carcinoembryonic antigen (CEA) in human serum was developed using carbon nanotube (CNT)-based symbiotic coaxial nanocables as labels. To construct such a nanocable, a thin layer of silica nanoparticles was coated on the CNT surface by sonication and sol–gel methods, and then colloidal gold nanoparticles were assembled on the amino-functionalized SiO2/CNTs, which were used for the label of horseradish peroxidase-anti-CEA conjugates (HRP-anti-CEA-Au/SiO2/CNT). In the presence of analyte CEA, the sandwich-type immunocomplex was formed on an anti-CEA/Au/thionine/Nafion-modified glassy carbon electrode by using HRP-anti-CEA-Au/SiO2/CNTs as detection antibodies. To embody the advantages of the protocol, the analytical properties of variously modified electrodes were compared in detail on the basis of different nanolabels. Under optimal conditions, the cathodic peak currents of the electrochemical immunosensor were proportional to the logarithm of CEA concentration over the range from 0.01 to 12 ng mL−1 in pH 5.5 HAc-NaAc containing 5 mM H2O2. At a signal-to-noise ratio of 3, the detection limit (LOD) is 5 pg mL−1 CEA. Intra- and inter-assay coefficients of variation were below 9.5%. Meanwhile, the selectivity and stability of the immunosensor were acceptable. In addition, the technique was evaluated by spiking CEA standards in pH 7.4 PBS and with 35 clinical serum specimens, receiving excellent accordance with results from commercially available electrochemiluminescent enzyme-linked immunoassay.
Co-reporter:Jingjing Ren, Dianping Tang, Biling Su, Juan Tang and Guonan Chen
Nanoscale 2010 vol. 2(Issue 7) pp:1244-1249
Publication Date(Web):20 Apr 2010
DOI:10.1039/B9NR00416E
Herein, we report a novel glucose oxidase (GOD)-doped magnetic silica nanostructure and its possible application in the clinical immunoassays. The doped nanostructures were initially synthesized using the reverse micelle method, and ferritin antibodies (anti-Ft) were then labeled to the surface of the nanostructures, which were employed as signal antibodies for ultrasensitive detection of ferritin (Ft) in the sandwich-type electrochemical enzyme immunoassays. The doped nanostructures were characterized using transmission electron microscopy (TEM), UV-vis absorption spectrometry and vibrating sample magnetometer (VSM). The advantages of the doped nanostructures as labels were investigated in comparison with the conventional label method. Under the optimal conditions, the nanostructures-based immunoassay toward ferritin standards displays a wide dynamic range from 0.1 to 400 ng mL−1 with a low detection limit of 10 pg mL−1 ferritin (at 3σ), which is three-fold higher in the sensitivity than that of directly using GOD-labeled antibodies. The assay results for clinical serum samples with the developed method received in excellent accordance with results obtained from the referenced standard enzyme-linked immunosorbent assay (ELISA) method.
Co-reporter:Dianping Tang, Biling Su, Juan Tang, Jingjing Ren and Guonan Chen
Analytical Chemistry 2010 Volume 82(Issue 4) pp:1527
Publication Date(Web):January 22, 2010
DOI:10.1021/ac902768f
A novel nanoparticle-based electrochemical immunoassay of carbohydrate antigen 125 (CA125) as a model was designed to couple with a microfluidic strategy using anti-CA125-functionalized magnetic beads as immunosensing probes. To construct the immunoassay, thionine−horseradish peroxidase conjugation (TH−HRP) was initially doped into nanosilica particles using the reverse micelle method, and then HRP-labeled anti-CA125 antibodies (HRP−anti-CA125) were bound onto the surface of the synthesized nanoparticles, which were used as recognition elements. Different from conventional nanoparticle-based electrochemical immunoassays, the recognition elements of the immunoassay simultaneously contained electron mediator and enzyme labels and simplified the electrochemical measurement process. The sandwich-type immunoassay format was used for the online formation of the immunocomplex in an incubation cell and captured in the detection cell with an external magnet. The electrochemical signals derived from the carried HRP toward the reduction of H2O2 using the doped thionine as electron mediator. Under optimal conditions, the electrochemical immunoassay exhibited a wide working range from 0.1 to 450 U/mL with a detection limit of 0.1 U/mL CA125. The precision, reproducibility, and stability of the immunoassay were acceptable. The assay was evaluated for clinical serum samples, receiving in excellent accordance with results obtained from the standard enzyme-linked immunosorbent assay (ELISA) method. Concluding, the nanoparticle-based assay format provides a promising approach in clinical application and thus represents a versatile detection method.
Co-reporter:Dianping Tang, Juan Tang, Biling Su, and Guonan Chen
Journal of Agricultural and Food Chemistry 2010 Volume 58(Issue 20) pp:10824-10830
Publication Date(Web):September 28, 2010
DOI:10.1021/jf102326m
A new sandwich-type electrochemical immunoassay for ultrasensitive detection of staphylococcal enterotoxin B (SEB) in food was developed using horseradish peroxidase-nanosilica-doped multiwalled carbon nanotubes (HRPSiCNTs) for signal amplification. Rabbit polyclonal anti-SEB antibodies immobilized on the screen-printed carbon electrode (SPCE) and covalently bound to the HRPSiCNTs were used as capture antibodies and detection antibodies, respectively. In the presence of SEB analyte, the sandwich-type immunocomplex could be formed between the immobilized anti-SEB on the SPCE and anti-SEB-labeled HRPSiCNTs, and the carried HRP could catalyze the electrochemical reduction of H2O2 with the help of thionine. The high content of HRP in the HRPSiCNTs could greatly amplify the electrochemical signal. Under optimal conditions, the reduction current increased with the increase of SEB in the sample, and exhibited a dynamic range of 0.05−15 ng/mL with a low detection limit (LOD) of 10 pg/mL SEB (at 3σ). Intra- and interassay coefficients of variation were below 10%. In addition, the assay was evaluated with SEB spiked samples including watermelon juice, soymilk, apple juice, and pork food, receiving excellent correlation with results from commercially available enzyme-linked immunosorbent assay (ELISA).
Co-reporter:Biling Su, Juan Tang, Huafeng Chen, Jianxin Huang, Guonan Chen and Dianping Tang
Analytical Methods 2010 vol. 2(Issue 11) pp:1702-1709
Publication Date(Web):30 Sep 2010
DOI:10.1039/C0AY00468E
A simple and sensitive electrochemical immunoassay method was developed for the detection of alpha-fetoprotein (AFP) in human serum. The immunoassay is based on the use of an AFP-functionalized thionine/nanogold multilayer film ({Thi/AuNP}n) on a single-walled carbon nanotubes (CNT)-coated gold electrode and double-codified gold nanoparticles with horseradish peroxidase-labelled anti-AFP antibodies (HRP-anti-AFP-AuNPs). With a competitive immunoassay format, the assay was performed using HRP-anti-AFP-AuNP as trace and H2O2 as enzyme substrate. The electrochemical behavior of the multilayer {Thi/AuNP}n films was studied. The maximal signal was obtained at n = 3 (i.e. {Thi/AuNP}3). Under optimal conditions, the obtained electrochemical responses were proportional to the AFP levels in the sample. The dynamic range for AFP quantification was 0.25–45 ng mL−1. Both the intra- and inter-assay coefficients of variation were less than 9.5%. The proposed assay had a detection limit of 0.05 ng mL−1, which was 20-fold vs. 10-fold lower than that obtained using monolayer Thi/AuNP film vs. conventional HRP-labelled anti-AFP antibodies. Importantly, no significant differences at the 0.05 confidence level were encountered in the analysis of clinical serum samples between the proposed immunoassay and the commercially available Roche 2010 Electrochemiluminescent (ECL) Automatic Analyzer for AFP determination.
Co-reporter:Juan Tang, Biling Su, Dianping Tang, Guonan Chen
Biosensors and Bioelectronics 2010 Volume 25(Issue 12) pp:2657-2662
Publication Date(Web):15 August 2010
DOI:10.1016/j.bios.2010.04.039
A new electrochemical immunoassay protocol for sensitive detection of α-fetoprotein (AFP, as a model) is designed using carbon nanoparticles (CNPs)-functionalized biomimetic interface as immunosensing probe and irregular-shaped gold nanoparticles (ISNGs)-labeled horseradish peroxidase-anti-AFP conjugates (HRP-anti-AFP-ISNG) as trace label. The low-toxic and high-conductive CNPs provided a high capacity nanoparticulate immobilization surface and a facile pathway for electron transfer. In comparison with conventional label methods, i.e. spherical gold nanoparticles-labeled HRP-anti-AFP and HRP-labeled anti-AFP, the electrochemical immunosensor using HRP-anti-AFP-ISNGs as trace labels exhibited high bioelectrocatalytic response toward enzyme substrate and a wide dynamic range from 0.02 to 4.0 ng/mL with a low detection limit of 10 pg/mL toward AFP (at 3σ). The developed immunoassay method showed good selectivity and acceptable reproducibility. Clinical serum samples with various AFP concentrations were evaluated by using the electrochemical immunosensor and the referenced enzyme-linked immunosorbent assay (ELISA), respectively, and received in good accordance with results obtained from these two methods.
Co-reporter:Zhuangqiang Gao, Zhenli Qiu, Minghua Lu, Jian Shu, Dianping Tang
Biosensors and Bioelectronics (15 March 2017) Volume 89(Part 2) pp:
Publication Date(Web):15 March 2017
DOI:10.1016/j.bios.2016.10.043
•We devise a new colorimetric detection protocol for target ATP.•Unmodified gold nanoparticles were used as the signal-generation tags.•Hybridization chain reaction was utilized for signal amplification.•Label-free hairpin probes were employed for ATP recognition.This work designs a new label-free aptasensor for the colorimetric determination of small molecules (adenosine 5′-triphosphate, ATP) by using visible gold nanoparticles as the signal-generation tags, based on target-triggered hybridization chain reaction (HCR) between two hairpin DNA probes. The assay is carried out referring to the change in the color/absorbance by salt-induced aggregation of gold nanoparticles after the interaction with hairpins, gold nanoparticles and ATP. To construct such an assay system, two hairpin DNA probes with a short single-stranded DNA at the sticky end are utilized for interaction with gold nanoparticles. In the absence of target ATP, the hairpin DNA probes can prevent gold nanoparticles from the salt-induced aggregation through the interaction of the single-stranded DNA at the sticky end with gold nanoparticles. Upon target ATP introduction, the aptamer-based hairpin probe is opened to expose a new sticky end for the strand-displacement reaction with another complementary hairpin, thus resulting in the decreasing single-stranded DNA because of the consumption of hairpins. In this case, gold nanoparticles are uncovered owing to the formation of double-stranded DNA, which causes their aggregation upon addition of the salt, thereby leading to the change in the red-to-blue color. Under the optimal conditions, the HCR-based colorimetric assay presents good visible color or absorbance responses for the determination of target ATP at a concentration as low as 1.0 nM. Importantly, the methodology can be further extended to quantitatively or qualitatively monitor other small molecules or biotoxins by changing the sequence of the corresponding aptamer.
Co-reporter:Guang-Zhou Li and Dianping Tang
Journal of Materials Chemistry A 2017 - vol. 5(Issue 28) pp:NaN5579-5579
Publication Date(Web):2017/06/15
DOI:10.1039/C7TB00670E
Herein, we design a simple and portable biosensing platform for the quantitative detection of cocaine based on target-triggered glucose release from a TiO2 nanotube array (TiNTA) with a glucometer readout. Initially, single-stranded DNA1 and DNA2 were covalently conjugated to the TiNTA and gold nanoparticle (AuNP), respectively. In the presence of cocaine aptamer and glucose, the immobilized DNA1 on the TiNTA and the labeled DNA2 on the AuNP simultaneously hybridized with the adjacent area of the aptamer, and gated the glucose molecules in the nanotubes. Upon the introduction of cocaine, the aptamer specifically reacted with an analyte to form the target–aptamer complex, thus resulting in the dissociation of DNA1–TiNTA and DNA2–AuNP to release glucose molecules from the nanotubes. The as-released glucose molecules could be determined on a personal glucometer (PGM). The experimental results revealed that the PGM signal increased with increasing cocaine concentration, and exhibited a wide linear range of 10–600 nM with a detection limit of 5.2 nM. Intra- and inter-assay relative standard deviations with identical batches were less than 9.3% and 12.7%, respectively. The specificity, reproducibility, and stability of our strategy were acceptable. Importantly, this concept offers promise for a rapid, simple, low-cost, and user-friendly analysis of small-molecular cocaine.
Co-reporter:Li Hou, Chunling Zhu, Xiaoping Wu, Guonan Chen and Dianping Tang
Chemical Communications 2014 - vol. 50(Issue 12) pp:NaN1443-1443
Publication Date(Web):2013/11/25
DOI:10.1039/C3CC48453J
A novel sensing platform for monitoring small molecules without the need for sample separation and washing is developed by using a commercialized personal glucose meter based on bioresponsive controlled release of glucose from aptamer-gated mesoporous silica nanocontainers.
Co-reporter:Bingqian Liu, Bing Zhang, Guonan Chen and Dianping Tang
Chemical Communications 2014 - vol. 50(Issue 15) pp:NaN1902-1902
Publication Date(Web):2013/12/09
DOI:10.1039/C3CC49005J
An omega (Ω)-like DNA nanostructure was for the first time utilized for homogenous electrochemical monitoring of small molecules (ATP used in this case) based on target-induced formation of DNAzyme–aptamer conjugates without the need for sample separation and washing.
Co-reporter:Zhuangqiang Gao, Dianping Tang, Mingdi Xu, Guonan Chen and Huanghao Yang
Chemical Communications 2014 - vol. 50(Issue 47) pp:NaN6258-6258
Publication Date(Web):2014/04/23
DOI:10.1039/C4CC01511H
A novel homogeneous immunoassay method is developed for sensitive monitoring of small molecular biotoxin by using a portable personal glucose meter (PGM) based on the target-responsive release of cargo (glucose) from a polystyrene microsphere-gated magnetic mesoporous nanocontainer.
Co-reporter:Junyang Zhuang, Libing Fu, Wenqiang Lai, Dianping Tang and Guonan Chen
Chemical Communications 2013 - vol. 49(Issue 95) pp:NaN11202-11202
Publication Date(Web):2013/10/08
DOI:10.1039/C3CC46869K
Target-stimulated metallic HgS nanostructures formed on the DNA-based polyion complex (PIC) membrane were for the first time utilized as an efficient scheme for impedimetric detection of hydrogen sulfide (H2S) by coupling insoluble precipitation with sensitivity enhancement.
Co-reporter:Juan Tang, Li Hou, Dianping Tang, Bing Zhang, Jun Zhou and Guonan Chen
Chemical Communications 2012 - vol. 48(Issue 66) pp:NaN8182-8182
Publication Date(Web):2012/06/07
DOI:10.1039/C2CC33390B
Hemin/G-quadruplex-based DNAzyme concatamers were utilized as electrocatalysts and biolabels to construct a sandwich-type electrochemical immunosensor for sensitive detection of IgG1 (as a model analyte).
Co-reporter:Libing Fu, Junyang Zhuang, Wenqiang Lai, Xiaohua Que, Minghua Lu and Dianping Tang
Journal of Materials Chemistry A 2013 - vol. 1(Issue 44) pp:NaN6128-6128
Publication Date(Web):2013/09/17
DOI:10.1039/C3TB21155J
A portable and quantitative monitoring protocol for sensitive detection of lead ions is designed, based on target-responsive cargo release from Pb2+-specific DNAzyme-capped mesoporous silica nanoparticles (MSNs), by coupling with a widely accessible personal glucose meter (PGM). Initially, glucose molecules are loaded into the pores of the MSNs, the pores are then capped with Pb2+-specific DNAzymes. Upon target introduction, the molecular gates open, resulting in release of the cargo from the pores. The released glucose can be quantitatively monitored using a portable PGM. Under optimal conditions, the as-prepared sensing platform presents good analytical properties for the determination of the target Pb2+ ions, and allows detection of Pb2+ at concentrations as low as 1.0 pM. Importantly, the portable sensing platform has the advantages of simple, on-site, user-friendly and low-cost assessment and has tremendous potential for quantitative detection of non-glucose targets by the public.
Co-reporter:Dianping Tang, Juan Tang, Biling Su, Qunfang Li and Guonan Chen
Chemical Communications 2011 - vol. 47(Issue 33) pp:NaN9479-9479
Publication Date(Web):2011/07/22
DOI:10.1039/C1CC13340C
A novel electrochemical method to detect hepatitis C virus was developed based on site-specific cleavage of BamHI endonuclease and enzymatic signal amplification with horseradish peroxidase-encapsulated nanogold hollow spheres.
Co-reporter:Yuling Cui, Huafeng Chen, Dianping Tang, Huanghao Yang and Guonan Chen
Chemical Communications 2012 - vol. 48(Issue 83) pp:NaN10309-10309
Publication Date(Web):2012/09/04
DOI:10.1039/C2CC35351B
A novel and redox-active nanocatalyst, Au(III)-promoted polyaniline gold nanosphere (GPANG), was designed as the nanolabel for highly efficient electrochemical immunoassay of human IgG by coupling with electrocatalytic recycling of self-produced reactants.
Co-reporter:Juan Tang, Dianping Tang, Jun Zhou, Huanghao Yang and Guonan Chen
Chemical Communications 2012 - vol. 48(Issue 20) pp:NaN2629-2629
Publication Date(Web):2012/01/16
DOI:10.1039/C2CC17536C
A simple, novel, label-free impedimetric aptasensor with signal amplification is developed for ultrasensitive detection of small molecules on a carbon nanotubes-based sensing platform by combining target-induced release of the aptamers and nuclease cleavage-assisted target recycling.
Co-reporter:Bingqian Liu, Yuling Cui, Dianping Tang, Huanghao Yang and Guonan Chen
Chemical Communications 2012 - vol. 48(Issue 20) pp:NaN2626-2626
Publication Date(Web):2012/01/16
DOI:10.1039/C2CC17790K
A redox-active Au(III)-assisted core–shell iron oxide@poly(o-phenylenediamine) nanostructure was designed as a sensing platform for ultrasensitive electrochemical detection of small molecules (ATP, used as a model here) by coupling with DNase I-catalyzed target recycling.
Co-reporter:Mingdi Xu, Junyang Zhuang, Xian Chen, Guonan Chen and Dianping Tang
Chemical Communications 2013 - vol. 49(Issue 66) pp:NaN7306-7306
Publication Date(Web):2013/06/24
DOI:10.1039/C3CC43205J
A novel difunctional DNA–nanogold (AuNP) dendrimer with a hemin–G-quadruplex was for the first time utilized as the nanotag for the in situ amplified electronic signal for nucleic acid detection by coupling high-efficiency DNAzyme with the intercalated methylene blue (MB).
Co-reporter:Jun Zhou, Mingdi Xu, Dianping Tang, Zhuangqiang Gao, Juan Tang and Guonan Chen
Chemical Communications 2012 - vol. 48(Issue 100) pp:NaN12209-12209
Publication Date(Web):2012/11/01
DOI:10.1039/C2CC36820J
A label-free, non-enzyme immunosensing strategy is designed for ultrasensitive electronic detection of disease-related proteins (carcinoembryonic antigen as a model) by using gold nanoparticle-based bio-bar codes and an in situ amplified DNA-based hybridization chain reaction.
Co-reporter:Juan Tang, Jun Zhou, Qunfang Li, Dianping Tang, Guonan Chen and Huanghao Yang
Chemical Communications 2013 - vol. 49(Issue 15) pp:NaN1532-1532
Publication Date(Web):2013/01/03
DOI:10.1039/C2CC38493K
Platinum–cerium oxide hybrid nanocatalysts (CeO2–Pt) were for the first time designed as bionanolabels for highly efficient electrochemical immunosensing of low-abundance proteins coupling nanocatalyst-based redox cycling with in situ signal amplification strategy.
Co-reporter:Junyang Zhuang, Wenqiang Lai, Guonan Chen and Dianping Tang
Chemical Communications 2014 - vol. 50(Issue 22) pp:NaN2938-2938
Publication Date(Web):2014/01/27
DOI:10.1039/C3CC49873E
A novel DNA nanomachine based on the linear rolling circle amplification strategy was designed for sensitive screening of microRNA (miRNA) at an ultralow concentration coupling catalytic hairpin assembly (CHA) with DNAzyme formation.
Co-reporter:Wenqiang Lai, Dianping Tang, Libing Fu, Xiaohua Que, Junyang Zhuang and Guonan Chen
Chemical Communications 2013 - vol. 49(Issue 42) pp:NaN4763-4763
Publication Date(Web):2013/04/05
DOI:10.1039/C3CC41708E
Squaric acid, a 2-dimensional planar structure of squarate C4O4 units linked by protons in a layered sheet, was utilized for the first time as a catalytic substrate for ultrasensitive electronic determination of low-abundance proteins by coupling a target-induced electrocatalytic reaction with the in situ cycling signal amplification strategy.
Co-reporter:Wenqiang Lai, Junyang Zhuang, Xiaohua Que, Libing Fu and Dianping Tang
Biomaterials Science (2013-Present) 2014 - vol. 2(Issue 8) pp:NaN1079-1079
Publication Date(Web):2014/03/10
DOI:10.1039/C3BM60284B
A new electrochemical immunosensor was designed for the determination of carcinoembryonic antigen (CEA) with sensitivity enhanced by using nanogold–poly(o-phenylenediamine)–manganese dioxide organic–inorganic hybrid nanostructures (GNPM) as nanotags and peroxidase mimics. Initially, mesoporous poly(o-phenylenediamine)–manganese dioxide (PPD–MnO2) hollow microspheres were synthesized by an inorganic/organic interfacial polymerization technique. Then gold nanoparticles were assembled onto the surface of PPD–MnO2, which were used for the labelling of the anti-CEA detection antibody (pAb2). The prepared GNPM nanotags were characterized using transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), UV-vis absorption spectroscopy, N2 adsorption–desorption isotherm measurements and Fourier transform infrared spectroscopy (FTIR). The assay was carried out with a sandwich-type immunoassay format in pH 5.5 acetic acid-buffered saline solution containing 2.5 mmol L−1 H2O2. Experimental results indicated that the electrochemical immunosensor exhibited a wide dynamic range from 0.01 to 80 ng mL−1 towards the target CEA with a detection limit (LOD) of 6.0 pg mL−1. The immunosensor also displayed a good stability and acceptable reproducibility and selectivity. In addition, the methodology was evaluated by assaying 10 clinical serum samples, providing a good relationship between the electrochemical immunosensor and the commercialized electrochemiluminescent (ECL) method for determination of CEA.
Co-reporter:Biling Su, Juan Tang, Huafeng Chen, Jianxin Huang, Guonan Chen and Dianping Tang
Analytical Methods (2009-Present) 2010 - vol. 2(Issue 11) pp:NaN1709-1709
Publication Date(Web):2010/09/30
DOI:10.1039/C0AY00468E
A simple and sensitive electrochemical immunoassay method was developed for the detection of alpha-fetoprotein (AFP) in human serum. The immunoassay is based on the use of an AFP-functionalized thionine/nanogold multilayer film ({Thi/AuNP}n) on a single-walled carbon nanotubes (CNT)-coated gold electrode and double-codified gold nanoparticles with horseradish peroxidase-labelled anti-AFP antibodies (HRP-anti-AFP-AuNPs). With a competitive immunoassay format, the assay was performed using HRP-anti-AFP-AuNP as trace and H2O2 as enzyme substrate. The electrochemical behavior of the multilayer {Thi/AuNP}n films was studied. The maximal signal was obtained at n = 3 (i.e. {Thi/AuNP}3). Under optimal conditions, the obtained electrochemical responses were proportional to the AFP levels in the sample. The dynamic range for AFP quantification was 0.25–45 ng mL−1. Both the intra- and inter-assay coefficients of variation were less than 9.5%. The proposed assay had a detection limit of 0.05 ng mL−1, which was 20-fold vs. 10-fold lower than that obtained using monolayer Thi/AuNP film vs. conventional HRP-labelled anti-AFP antibodies. Importantly, no significant differences at the 0.05 confidence level were encountered in the analysis of clinical serum samples between the proposed immunoassay and the commercially available Roche 2010 Electrochemiluminescent (ECL) Automatic Analyzer for AFP determination.
Co-reporter:Huafeng Chen, Bing Zhang, Yuling Cui, Bingqian Liu, Guonan Chen and Dianping Tang
Analytical Methods (2009-Present) 2011 - vol. 3(Issue 7) pp:NaN1621-1621
Publication Date(Web):2011/06/21
DOI:10.1039/C1AY05172E
A rapid and sensitive one-step electrochemical immunoassay for the determination of α-fetoprotein (AFP, as a model biomarker) was developed by immobilizing anti-AFP antibody on a nanogold-functionalized graphene interface. Initially, thionine molecules as electron mediators were conjugated onto the surface of graphene nanosheets, then gold nanoparticles were sandwiched onto the graphene, and then horseradish peroxidase-anti-AFP (HRP-anti-AFP) conjugates were immobilized on the nanogold surface. The presence of two-dimensional graphene nanosheets with high conductivity not only increased the surface coverage of the electrode, but also enhanced the immobilized amount of biomolecules. With the AFP analyte, the formed antigen–antibody complex was coated on the electrode surface, which partially hindered the immobilized HRP toward the catalytic reduction of H2O2 in the solution. Under optimal conditions, the electrochemical immunosensor displayed a wide dynamic range of 0.1–200 ng mL−1 with a detection limit (LOD) of 0.05 ng mL−1 AFP at 3sB. The reproducibility, selectivity and stability of the immunosensor were investigated with the acceptable results. In addition, the one-step immunoassay was evaluated and validated by assaying 5 positive and 5 negative serum specimens, and the obtained results were compared with those by the referenced electrochemiluminescent, receiving a good correlation between the two methods.
Co-reporter:
Analytical Methods (2009-Present) 2014 - vol. 6(Issue 10) pp:
Publication Date(Web):
DOI:10.1039/C4AY00086B
A novel signal-amplified strategy for sensitive electrochemical immunoassay of cancer marker (human tissue polypeptide antigen, TPA, used in this case) is developed by using Prussian blue nanoparticles-doped nanogold microsphere (AuPB) as the promoter. To construct such an immunoassay, the AuPB was initially synthesized by using the reverse micelle method, and the as-synthesized AuPB was then heavily functionalized with horseradish peroxidase (HRP) and anti-TPA antibody. Based on a specific sandwich-type immunoassay format, target TPA was monitored on anti-TPA-functionalized glassy carbon electrode by using the biofunctional AuPB as the signal tag. Compared with conventional nanogold labeling, the as-prepared AuPB possessed good redox activity, which could be employed as an electron mediator for improvement of catalytic efficiency of the labeled HRP. Under optimal conditions, the electrochemical immunoassay presents good electrochemical responses toward target TPA, and allowed the detection of TPA at a concentration as low as 5 pg mL−1. The precision, reproducibility, specificity and stability of the electrochemical immunoassay are acceptable. In addition, the methodology is validated for the analysis of 8 clinic human serum specimens and 8 spiked serum samples, receiving in good accordance with the results obtained from the referenced enzyme-linked immunosorbent assay (ELISA) method.
Co-reporter:Zhenzhen Lin, Shuzhen Lv, Kangyao Zhang and Dianping Tang
Journal of Materials Chemistry A 2017 - vol. 5(Issue 4) pp:NaN833-833
Publication Date(Web):2016/12/29
DOI:10.1039/C6TB03042D
This work designs a simple low-cost visual fluorescence immunoassay for disease-related biomarkers (carcinoembryonic antigen, CEA, used as a model protein) in biological fluids, based on the structural and optical transformation of CdTe quantum dots (QDs) immobilized on paper induced by dissolved silver ions (Ag+) from silver nanoparticles (AgNPs) via a cation-exchange reaction. A sandwich-type immunoreaction was initially carried out in a removable polystyrene high-binding microplate coated with monoclonal anti-CEA capture antibody by using AgNP-labeled polyclonal anti-CEA antibody as the detection antibody. Thereafter, the carried AgNPs accompanying the sandwiched immunocomplexes were dissolved by acid to release numerous silver ions, which induced the ion-exchange reaction with the immobilized CdTe QDs on the paper (attached onto the microplate lid) for the Cd-to-Ag transformation, thus resulting in the quenching of the visual fluorescence from the CdTe QDs owing to Ag2Te formation. Under optimal conditions, the fluorescence intensity decreased with the increasing CEA concentration from 0.02 to 50 ng mL−1 with a detection limit of 5.6 pg mL−1. Further, a visual assay based on a CdTe QD-based paper sensor was developed for CEA detection, and 5.0 pg mL−1 CEA could be discriminated with the naked eye. In addition, our strategy displayed high specificity, good reproducibility and acceptable accuracy for analyzing human serum specimens with consistent results obtained using the commercialized enzyme-linked immunosorbent assay (ELISA) method.
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