Co-reporter:Wanwan Cui;Yanyan Wang;Dandan Yang
Microchimica Acta 2017 Volume 184( Issue 12) pp:4749-4755
Publication Date(Web):26 September 2017
DOI:10.1007/s00604-017-2525-4
Nanosheets of cobalt oxyhydroxide (CoOOH) are found to exhibit oxidase–like activity and can catalyze the oxidation of the substrate 3,3′,5,5′–tetramethylbenzidine (TMB) by oxygen in weakly acidic solution even in the absence of hydrogen peroxide. On the basis of this property, a fluorometric assay was designed in which the blue oxidation product of TMB (oxTMB) reduces the intensity of the fluorescence of albumin–stabilized gold nanoclusters (BSA–AuNCs). The fluorescence of the AuNCs under 502 nm photoexcitation has a peak at 620 nm which overlaps the absorption band of oxTMB. As a result, fluorescence is reduced. The findings were used to develop a method for the fluorometric quantitation of ascorbic acid. Ascorbic acid is capable of destroying some of the CoOOH nanosheets, and hence catalytic oxidation is retarded and fluorescence will be less strongly reduced (i.e., reabsorbed). Fluorescence intensity increases in the 0.75 to 20 μM ascorbic acid concentration range, and the detection limit is 0.2 μM. The method is well reproducible (the relative standard deviation of 1.6% for 11 replicates at a 10 μM ascorbic acid level). The practicability of the method was demonstrated by the analysis of ascorbic acid in tablets and juices.
Co-reporter:Wanwan Cui;Haiyan Qin;Yang Zhou
Microchimica Acta 2017 Volume 184( Issue 4) pp:1103-1108
Publication Date(Web):2017 April
DOI:10.1007/s00604-017-2110-x
The authors describe a rapid and sensitive method for the determination of the activity of scavenging hydrogen peroxide in which glucose oxidase–stabilized gold nanoclusters (AuNCs) were employed as a fluorescent nanoprobe. The AuNCs are synthesized by a biomineralization process and display an intense blue fluorescence peaking at 450 nm and a quantum yield of 1.1% under 360–nm excitation. The Fenton reaction induces quenching of fluorescence, and this effect can be used to determine H2O2 in the 0.5 to 10 μmol⋅L−1 concentration range. The substances displaying H2O2 scavenging activity prevent quenching and thus restore fluorescence. The intensity of restored fluorescence is directly related to the H2O2 scavenging activity of the antioxidant. The method was applied to the determination of the H2O2 scavenging activity of the model antioxidants ascorbic acid and tartaric acid which gave IC50 values of 7.4 and 19.1 μmol⋅L−1, respectively.
Co-reporter:Lufeng Zhang, Haiyan Qin, Wanwan Cui, Yang Zhou, Jianxiu Du
Talanta 2016 Volume 161() pp:535-540
Publication Date(Web):1 December 2016
DOI:10.1016/j.talanta.2016.09.011
•A simple, label–free and turn–on fluorescent sensor for trypsin was fabricated.•Cytochrome c was selected as the natural substance of trypsin.•Trypsin cleaved cytochrome c into heme–peptide fragment.•Heme–peptide fragment catalyzed H2O2 oxidizing thiamine to fluorescent thiochrome.•The method was applied to screen the inhibitor of trypsin.The development of new detection methods for proteases activity assay is important in clinical diagnostics and drug development. In this work, a simple, label–free, and turn–on fluorescent sensor was fabricated for trypsin, a protease produced in the pancreas. Cytochrome c, a natural substance of trypsin, could be selectively cleaved by trypsin into heme–peptide fragment. The produced heme–peptide fragment exhibited an intensive catalytic role on the H2O2–mediated the oxidation of thiamine to form strong fluorescent thiochrome. The fluorescence intensity was closely dependent on the amount of trypsin presented. The procedure allowed the measurement of trypsin over the range of 0.5–20.0 μg/mL with a detection limit of 0.125 μg/mL. The sensor showed better precision with a relative standard deviation of 1.6% for the measurement of 1.0 μg/mL trypsin solution (n=11). This sensing system was applied to screen the inhibitor of trypsin, the IC50 values were calculated to be 12.71 ng/mL for the trypsin inhibitor from soybean and 2.0 μg/mL for benzamidine hydrochloride, respectively, demonstrating its potential application in drug development and related diseases treatment.
Co-reporter:Lufeng Zhang, Jianxiu Du
Biosensors and Bioelectronics 2016 Volume 79() pp:347-352
Publication Date(Web):15 May 2016
DOI:10.1016/j.bios.2015.12.070
•A trypsin colorimetric sensor was developed with cytochrome c as substrate.•The hydrolysate of cytochrome c by trypsin intensely catalyzes the TMB-H2O2 reaction.•The sensor is low cost, label-free and highly sensitive.•As low as 50 ng/mL trypsin can be visually perceived with the naked eyes.•It was successfully used for detecting trypsin in urine and screening the inhibitor.The development of simple and sensitive methods for protease sensing plays important roles in clinical diagnostics and drug development. Here a simple, rapid, label-free, and sensitive trypsin colorimetric sensor was developed by employing cytochrome c (cyt c) as an enzyme substrate and 3,3´,5,5´-tetramethylbenzidine (TMB) as a chromogenic reagent. It was found that cyt c hardly catalyzes H2O2-mediated TMB oxidation to produce a blue solution. But the hydrolysate of cyt c by trypsin displays an intense catalytic effect on the aforementioned reaction, resulting in the formation of a blue solution immediately. The detection process allows visually perceiving as low as 50 ng/mL trypsin with the naked eyes. With the aid of a spectrophotometer, the absorbance at 652 nm was proportional to the concentration of trypsin in the range from 5.0 ng/mL to 2.0 μg/mL with a detection limit of 4.5 ng/mL. The sensor showed better precision with relative standard deviation of 2.5% and 1.7% for eleven repetitive measurements of 50.0 ng/mL and 1.0 μg/mL trypsin solution, respectively. The procedure has been successfully applied to the determination of trypsin in human urines and for inhibitor screening, demonstrating its potential application in clinic diagnosis and drug development.
Co-reporter:Xuemei Yang, Jianxiu Du, Yang Zhou
Sensors and Actuators B: Chemical 2016 Volume 232() pp:738-743
Publication Date(Web):September 2016
DOI:10.1016/j.snb.2016.04.036
•Sulfide photometer with integrating gas separation/paper enrichment was fabricated.•The bubble of gas promotes the mixing and the liberation of H2S.•H2S was captured and enriched on methyl green-impregnated paper filter.•Defoaming agent SE-15 effectively prevents the frothing during aeration.•Serum sulfide can be accurately measured in 2.5 min.Hydrogen sulfide (H2S) has recently been recognized as the third important physiologically gasotransmitter after carbon monoxide and nitrogen monoxide. The challenge of accurate measurement of H2S at micromolar levels in biological samples represents a major impediment to the investigation of H2S. Here a light emitting diode-based photometer was fabricated for the rapid and point of care measurement of sulfide in human serum samples via marriage of gas separation with paper enrichment. Sulfide in the sample was converted into H2S by the addition of diluted H3PO4 and liberated from the sample matrix by the bubble of nitrogen gas (N2). The liberated H2S was subsequently captured by a methyl green-impregnated paper filter placed at front of the detector. Upon reaction with H2S, the paper filter decolorized that was real-time monitored in transmission mode. With 0.2 mL sample, serum sulfide level within the range 10.0–200.0 μmol/L can be accurately measured in less than 2.5 min. The bubble of N2 into the matrix promotes the mixing of sample with the added acid and helps the liberation of H2S. The addition of defoaming agent SE-15 into the matrix effectively prevented the frothing during aeration. The device was applied to the determination of sulfide in human serum and compared satisfactory with that of methylene blue method implemented on a commercial spectrophotometer.
Co-reporter:Lufeng Zhang, Jianxiu Du
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2016 Volume 158() pp:24-28
Publication Date(Web):5 April 2016
DOI:10.1016/j.saa.2016.01.012
•A colorimetric method was developed for the determination of Fe(III).•Fe(III) directly oxidized 3,3,′5,5′-tetramethylbenzidine to produce blue solution.•The method benefited the characteristics of low cost, sensitivity and selectivity.•As low as 1.0 μmol/L Fe(III) could be perceived by the naked eyes.•Iron content in milks was successfully determined.The development of highly selective and sensitive method for iron(III) detection is of great importance both from human health as well as environmental point of view. We herein reported a simple, selective and sensitive colorimetric method for the detection of Fe(III) at submicromolar level with 3,3,′5,5′-tetramethylbenzidine (TMB) as a chromogenic probe. It was observed that Fe(III) could directly oxidize TMB to form a blue solution without adding any extra oxidants. The reaction has a stoichiometric ratio of 1:1 (Fe(III)/TMB) as determined by a molar ratio method. The resultant color change can be perceived by the naked eye or monitored the absorbance change at 652 nm. The method allowed the measurement of Fe(III) in the range 1.0 × 10− 7–1.5 × 10− 4 mol L− 1 with a detection limit of 5.5 × 10− 8 mol L− 1. The relative standard deviation was 0.9% for eleven replicate measurements of 2.5 × 10− 5 mol L− 1 Fe(III) solution. The chemistry showed high selectivity for Fe(III) in contrast to other common cation ions. The practically of the method was evaluated by the determination of Fe in milk samples; good consistency was obtained between the results of this method and atomic absorption spectrophotometry as indicated by statistical analysis.
Co-reporter:Fang Lu, Qingqing Mao, Rui Wu, Shenghai Zhang, Jianxiu Du and Jiagen Lv
Lab on a Chip 2015 vol. 15(Issue 2) pp:495-503
Publication Date(Web):06 Nov 2014
DOI:10.1039/C4LC01248H
For pump-free, material abundant, portable, and easy-to-operate low-cost microfluidics, a siphonage flow microfluidic thread-based analytical device (S-μTAD) platform enabling quantitative and sensitive assays was designed. Renewable and continuous siphonage flow allowed replicate sampling and detection on one channel/device, obviating some possible inconsistencies among channels or devices. Y-shaped channels were fabricated with polyester cotton blend thread, due to its greater chemiluminescent sensitivity in comparison with that of cotton and polyester threads. S-μTAD sensors for glucose and uric acid were fabricated by using oxidase-immobilized cotton thread as the sample arm of the channels. The acceptable reproducibility and high sensitivity, demonstrated by the relative standard deviations of less than 5% in all cases and the detection limits of 4 × 10−8 mol L−1 for hydrogen peroxide, 1 × 10−7 mol L−1 for glucose, and 3 × 10−6 mol L−1 for uric acid, demonstrated the feasibility of the S-μTAD for quantitative assays. Good agreements between S-μTAD/sensor results and hospital results for blood glucose and uric acid assays indicated the capability of S-μTAD/sensors for the analysis of real samples. These findings proved the utility of siphonage for low-cost microfluidics and the suitability of our S-μTAD design for quantitative assays.
Co-reporter:Xuemei Yang, Jianxiu Du, Yinhuan Li
Talanta 2015 Volume 141() pp:207-211
Publication Date(Web):15 August 2015
DOI:10.1016/j.talanta.2015.04.003
•A cost-efficient and portable sulfide device was fabricated.•Gas-permeable isolation and long path absorbance detection was in situ integrated.•Submicromolar level of sulfide was determined in 1.5 min by the device.•With 0.2 mL sample, sulfide in human serum can be measured.A cost-efficient and portable device for detecting sulfide at submicromolar level was fabricated by in situ integrating gas-permeable porous tube isolation and long path absorbance detection. The device consisted of a pair of petri dish, having a diametrically strung porous membrane tube in the top cover. The ends of the tube were terminated by a light emitting diode and a photodiode via plugging acrylic optical fiber into the light input/output of tees. Sulfide put in the bottom dish was liberated by addition of diluted acid through a port on the cover. The liberated hydrogen sulfide diffused into the porous membrane tube and reacted with alkaline nitroprusside acceptor in the tube. The color change in the long path porous membrane tube cell was real-time monitored in the transmission mode. The device responded linearly to sulfide concentration over the range of 0.5–150.0 μmol/L with relative standard deviations less than 5% in all cases. The limits of detection for sulfide were within the range 0.2–1.5 μmol/L in aqueous standard and newborn calf serum. The device was successfully applied to the determination of sulfide in human serum samples.
Co-reporter:Weimin Zhang, Diao Ma, Jianxiu Du
Talanta 2014 Volume 120() pp:362-367
Publication Date(Web):March 2014
DOI:10.1016/j.talanta.2013.12.028
•Prussian blue nanoparticles were demonstrated to exhibits intrinsic peroxidase-like catalytic activity.•Prussian blue nanoparticles was successfully used as a peroxidase mimetics for highly sensitive colorimetric detection of H2O2 and glucose.•The method can be applied to the determination of glucose in human serum samples.Prussian blue nanoparticles (PB NPs) exhibits an intrinsic peroxidase-like catalytic activity towards the hydrogen peroxide (H2O2)-mediated oxidation of classical peroxidase substrate 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt to produce a colored product. The catalysis follows Michaelis–Menen kinetics and shows strong affinity for H2O2. Using PB NPs as a peroxidase mimetics, a colorimetric method was developed for the detection of 0.05–50.0 μM H2O2, with a detection limit of 0.031 μM. When the catalytic reaction of PB NPs was coupled with the reaction of glucose oxidation catalyzed by glucose oxidase, a sensitive and selective colorimetric method for the detection of glucose was realized. The limit of detection for glucose was determined to be as low as 0.03 μM and the linear range was from 0.1 μM to 50.0 μM. The method was successfully applied to the determination of glucose in human serum. Compared with other nanomaterials-based peroxidase mimetics, PB NPs provides 10–100 times higher sensitivity toward the detection of H2O2 and glucose. The detection platform developed showed great potential applications in varieties of physiological importance substances when merged with appropriate H2O2-producing oxidases.Prussian blue nanoparticles exhibit intrinsic peroxidase-like activity, providing a highly sensitive colorimetric detection method for H2O2 and glucose.
Co-reporter:Jiao Li, Jie Quan, Jianxiu Du, Mei Liu
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2013 Volume 114() pp:33-37
Publication Date(Web):October 2013
DOI:10.1016/j.saa.2013.04.097
•A simple and sensitive CL method was developed for the determination of trimetazidine.•Trimetazidine enhanced the CL signal of N-bromosuccinimide-luminol reaction in the presence of gold nanoparticles.•The method was successfully applied to the determination of trimetazidine in tablets and in spiked serum samples.•A possible CL reaction mechanism was suggested.A simple, rapid and sensitive chemiluminescence (CL) method combined with flow injection analysis was developed for the determination of trimetazidine. Trimetazidine was found to significantly increase the CL signal arising from N-bromosuccinimide-luminol reaction in the presence of gold nanoparticles. The enhanced CL intensity was proportional to trimetazidine concentration in the range of 0.01–5.0 μg/mL, with a limit of detection (3sb) of 6.7 ng/mL. The relative standard deviation was 2.8% for 11 repetitive measurements of 0.1 μg/mL trimetazidine solution. The practicality of the method was evaluated by determining trimetazidine in pharmaceutical formulations and in spiked human serum samples. Moreover, the possible CL reaction mechanism was also discussed.Graphical abstractTrimetazidine induced the aggregation of gold nanoparticles (AuNPs), resulting in signal amplification in luminol-N-bromosuccinimide-AuNPs chemiluminescence system, providing a simple and sensitive detection method for trimetazidine.
Co-reporter:Dr. Jianxiu Du;Yadi Wang ;Weimin Zhang
Chemistry - A European Journal 2012 Volume 18( Issue 27) pp:8540-8546
Publication Date(Web):
DOI:10.1002/chem.201200013
Abstract
A label-free, non-derivatization chemiluminescence resonance energy transfer (CRET) detection platform has been developed for the detection of the non-fluorescent small molecule 6-mercaptopurine. This CRET process arose from a chemiluminescent (CL) donor–acceptor system in which the reaction of bis(2,4,6-trichlorophenyl)oxalate (TCPO)–H2O2–fluorescein (maximum emission at 521.6 nm) served as the donor and gold nanoparticles (AuNPs, maximum absorption at 520.0 nm) served as the acceptor. This process caused a significant decrease in the CL signal of the TCPO–H2O2–fluorescein reaction. The presence of 6-mercaptopurine induced an aggregation of AuNPs with the assistance of Cu2+ ions through cooperative metal–ligand interactions that was accompanied by a distinct change in color and optical properties. The maximum absorption band of the AuNPs was red-shifted to 721.0 nm and no longer overlapped with the CL spectrum of the reaction; as a result, the CL signal was restored. This CRET system exhibited a wide linear range, from 9.0 nmol L−1 to 18.0 μmol L−1, and a low detection limit (0.62 nmol L−1) for 6-mercaptopurine. The applicability of the proposed CRET system was evaluated by analysis of 6-mercaptopurine in spiked human plasma samples.
Co-reporter:Jianxiu Du, Jie Quan, Yadi Wang
Talanta 2012 Volume 90() pp:117-122
Publication Date(Web):15 February 2012
DOI:10.1016/j.talanta.2012.01.014
A new chemiluminescence (CL) method combined with flow injection technique was developed for the determination of timolol maleate. Gold nanoparticles was found to catalyze the CL reaction of luminol with N-bromosuccinimide in an alkaline condition. The CL signal was furtherly enhanced significantly when timolol maleate was presented in the reaction system. But timolol maleate alone inhibited the CL signal from luminol–N-bromosuccinimide reaction slightly. Under the selected conditions, the enhanced CL intensity was linearly related to timolol maleate concentration in the range of 0.01–5.0 mg/L with a detection limit of 7.6 μg/L. The relative standard deviation was 2.7% for 11 repeated measurements of 0.1 mg/L timolol maleate solution. The proposed method was applied to the determination of timolol maleate in eye drops and in spiked human urine. A discussion on the possible CL reaction mechanism was also presented.Highlights► A new flow injection CL method was developed for timolol maleate. ► AuNPs with the sizes in the range of 6–99 nm was found to catalyze the CL reaction of luminol with N-bromosuccinimide. ► The CL signal was furtherly increased by timolol maleate significantly. ► A thorough discussion on CL reaction mechanism was presented.
Co-reporter:Jianxiu Du;Dongdong Li ;Jiuru Lu
Luminescence 2010 Volume 25( Issue 1) pp:76-80
Publication Date(Web):
DOI:10.1002/bio.1148
Abstract
A simple and sensitive chemiluminescence (CL) method combined with flow injection technique was developed for the determination of naproxen. It was based upon the weak CL signal arising from the reaction of KIO4 with H2O2 being significantly increased by naproxen in the presence of europium(III) ion. The experimental conditions that affected the CL signal were carefully optimized and the CL reaction mechanism was briefly discussed. Under the optimum conditions, the increment of CL intensity was proportional to the concentration of naproxen ranging from 5.0 × 10−8 to 5.0 × 10−6 g/mL. The detection limit was 1 × 10−8 g/mL naproxen and the relative standard deviation for 5.0 × 10−7 g/mL naproxen solution was 2.1% (n = 11). The proposed method was applied to the determination of naproxen in tablets and in spiked human urine samples with satisfactory results. Copyright © 2009 John Wiley & Sons, Ltd.
Co-reporter:Dongdong Li;Jiuru Lu
Microchimica Acta 2008 Volume 161( Issue 1-2) pp:169-173
Publication Date(Web):2008 April
DOI:10.1007/s00604-007-0931-8
A simple flow injection chemiluminescence (CL) method was developed for the determination of atenolol using Eu3+ as the probe. It was found that the weak CL generated by the KMnO4-Na2SO3 reaction can be significantly enhanced by the atenolol-Eu3+ complex. The experimental conditions were optimized. The CL intensity was linearly related to atenolol concentration in the range from 8.0 × 10−9 to 1.0 × 10−5 g mL−1. The detection limit (3sb) was 3 × 10−9 g mL−1 and the relative standard deviation for 1.0 × 10−7 g mL−1 atenolol solution was 2.4% (n = 11). The method has high sensitivity, wide linear range, inexpensive instrumentation, and has been applied to the determination of atenolol in spiked human urine and plasma samples with recoveries within the range 95.5–104.0%.
Co-reporter:Jianxiu Du, Liang Hao, Yinhuan Li, Jiuru Lu
Analytica Chimica Acta 2007 Volume 582(Issue 1) pp:98-102
Publication Date(Web):16 January 2007
DOI:10.1016/j.aca.2006.08.058
A simple flow injection chemiluminescence (FI-CL) method was proposed for the determination of nitrofurazone. Strong CL signal was generated during the reaction of nitrofurazone with H2O2 and N-bromosuccinimide (NBS) in alkaline condition. The CL signal was proportional to the nitrofurazone concentration in the range 1.0 × 10−7 to 1.0 × 10−5 g mL−1. The detection limit was 2 × 10−8 g mL−1 nitrofurazone and the relative standard deviation was less than 4% (6.0 × 10−6 g mL−1 nitrofurazone, n = 11). The proposed method was successfully applied to the determination of nitrofurazone in compound furacillin nasal drops, human plasma and urine samples. The CL reaction mechanism was also discussed briefly. Singlet oxygen generated in the reaction between H2O2 and NBS was suggested to be participated in the CL reaction.
Co-reporter:Jian-Xiu Du;Yin-Huan Li;Rong Guan
Microchimica Acta 2007 Volume 158( Issue 1-2) pp:145-150
Publication Date(Web):2007 April
DOI:10.1007/s00604-006-0681-z
A new chemiluminescence (CL) method combined with flow injection technique is described for the determination of Cr(III) and total Cr. It is found that a strong CL signal is generated from the reaction of Cr(III), lucigenin and KIO4 in alkaline condition. The determination of total Cr is performed by pre-reduction of Cr(VI) to Cr(III) by using H2SO3. The CL intensity is linearly related to the concentration of Cr in the range 4.0 × 10−10–1.0 × 10−6 g mL−1. The detection limit (3sb) is 1 × 10−10 g mL−1 Cr and the relative standard deviation is 1.9% (5.0 × 10−8 g mL−1 of Cr(III) solution, n = 11). The method was applied to the determination of Cr(III) and total Cr in water samples and compared satisfactorily with the official method.
Co-reporter:Jianxiu Du;Jiuru Lu
Luminescence 2006 Volume 21(Issue 1) pp:26-30
Publication Date(Web):15 AUG 2005
DOI:10.1002/bio.878
A weak chemiluminescence (CL) signal was observed during the mixing of isoniazid with lucigenin in alkaline aqueous solution. The CL signal was enhanced more than 100 times in the presence of potassium periodate. This CL system was developed for the determination of isoniazid using a flow injection mode. The CL intensity is proportional to the concentration of isoniazid in the range 0.005–1.0 mg/L. The limit of detection is 0.0034 mg/L and the relative standard deviation is 2.0% for 0.2 mg/L isoniazid solution in 11 repeated measurements. The method was applied to the determination of isoniazid in pharmaceutical preparations and satisfactory results were obtained. Copyright © 2005 John Wiley & Sons, Ltd.
Co-reporter:Jianxiu Du;Yinhuan Li;Jiuru Lu
Luminescence 2005 Volume 20(Issue 1) pp:30-35
Publication Date(Web):31 JAN 2005
DOI:10.1002/bio.798
The reaction of soluble manganese (IV) with sulphite in acidic condition was found to elicit weak chemiluminescence (CL). The CL signal was remarkably enhanced in the presence of three fluoroquinolones, viz. norfloxacin, ofloxacin and ciprofloxacin. Based on these observations, a new flow-injection CL method was developed for the determination of these fluoroquinolones. The method allows determination in the range 5.0 × 10−8–1.0 × 10−6 mol[sol ]L for norfloxacin, 1.0 × 10−7–8.0 × 10−6 mol[sol ]L for ofloxacin and 1.0 × 10−7–3.0 × 10−5 mol[sol ]L for ciprofloxacin, with detection limits of 3 × 10−8 mol[sol ]L, 5 × 10−8 mol[sol ]L and 3 × 10−8 mol[sol ]L, respectively. The method was applied to the determination of fluoroquinolones in pharmaceutical preparations. Copyright © 2005 John Wiley & Sons, Ltd.
![3',6'-Dihydroxy-3H-spiro[isobenzofuran-1,9'-xanthen]-3-one](http://img.cochemist.com/ccimg/2400/2321-07-5.png)
![3',6'-Dihydroxy-3H-spiro[isobenzofuran-1,9'-xanthen]-3-one](http://img.cochemist.com/ccimg/2400/2321-07-5_b.png)
