•An ultrasensitive SPR sensor of femtomolar-level DNA detection was developed with triple-dual amplification.•CuNPs could be in situ synthesized with the templates of poly-T sequences in dsDNA origami individuals.•Catechol violet was selected as a real-time initiator for mass reply by labeled CuNPs@dsDNA.For the efficient surface plasmon resonance (SPR)-based DNA assay researching, signal amplification tactics were absolutely necessary. In this work, a sensitive SPR-DNA sensor was developed by employing in situ synthesis of copper nanoparticles (CuNPs) templated by poly-T sequences DNA from terminal deoxynucleotidyl transferase (TdT)-mediated extension, and synergistically with nano-effect deposition as the mass relay. The objective of this strategy was manifold: firstly, tDNA hybridized with the optimal designed probes to active the TdT-mediated DNA extension onto the surface of SPR chip, resulted a long poly-T sequences ssDNA chain in dsDNA terminal onto surface of gold chip and characterized by SPR signal amplitudes. Secondly, copper ion (Cu2+) adsorbed into the skeleton of poly-T sequences DNA, with the aid of ascorbic acid (VC) to achieve the Cu2+ reduction, copper nanostructures (CuNPs) was synchronously generated onto the single nucleotide chain anchoring in dsDNA derivatives and the formation was featured by transmission electron micrographs (TEM) and electrochemistry. Lastly, dsDNA-complexed CuNPs (CuNPs@dsDNA) triggered the final signal amplification via real-time conversion of the additive catechol violet (CV) into oligomer or chelation precipitation by CuNPs-tagged reporters. With the proposed setups, a precise and replicable DNA sensing platform for specific target oligo was obtained with a detection limit down to 3.21 femtomolar, demonstrating a beneficial overlapping exploitation of nanomaterials and biochemical reaction as unique SPR infrastructure. Such triple-amplification strategic setups, the possibility of various methods abutment and biocompatibility weight reactor was amassed and adapted to more biological detection field.

•A femtomolar SPR-DNA sensing was developed by synergizing dual amplifiers.•Graphene-supported pyrenyls were on-chip assembled in favor of a captor forest.•Mass effect of real-time biocatalytic polymerization jointly sensitized SPR output.A highly efficient surface plasmon resonance (SPR)-based DNA assay was developed, by employing noncovalently functionalized graphene nanosheets as a substrate, and enzymatic catalysis-induced polymerization as mass relay. The objective of this strategy was manifold: first of all, to sensitize the overall SPR output by in situ optimized electrogeneration of graphene thin-film, which was characterized by atomic force microscopic topography; secondly, to regulate the self-assembly and orientation of biotinylated capture probes on nickel-chelated nitrilotriacetic acid (NTA) scaffolds, that anchored onto graphene-supported pyrenyl derivatives; and lastly, to synergize the signal amplification via real-time conversion of the additive aniline into polyaniline precipitation by horseradish peroxidase-tagged reporters. With this setup, a precise and replicable DNA sensing platform for specific targets was achieved with a detection limit down to femtomolar, thus demonstrating a beneficial exploration and exploitation of two-dimensional nanomaterials as unique SPR infrastructure. The possibility of such ″bottom-up″ architecture mounted with ″top-down″ weight reactor would be most likely extensible and adaptable to protein determinations.

A Zr-based metal–organic framework with zinc tetrakis(carboxyphenyl)-porphyrin (ZnTCPP) groups (MOF-525-Zn) was utilized to develop a novel electrochemiluminescence (ECL) biosensor for highly sensitive protein kinase activity assay. In this work, in terms of ECL measurements and cyclic voltammetry, the cathodic ECL behaviors of MOF-525-Zn in aqueous media were thoroughly investigated for the first time. The photoelectric active groups ZnTCPP on the MOF-525-Zn frameworks could promote the generation of singlet oxygen (1O2) via a series of electrochemical and chemical reactions, resulting in a strong and stable red irradiation at 634 nm. Additionally, the surfactant tetraoctylammonium bromide (TOAB) further facilitated dissolved oxygen to interact with the active sites ZnTCPP of MOF-525-Zn. Furthermore, the inorganic Zr–O clusters of MOF-525-Zn were simultaneously served as the recognition sites of phosphate groups. And then, an ultrasensitive ECL sensor was proposed for protein kinase A (PKA) activity detection with a linear range from 0.01 to 20 U mL−1 and a sensitive detection limit of 0.005 U mL−1. This biosensor can also be applied for quantitative kinase inhibitor screening. Finally, it exhibits good performance with high stability and acceptable fabrication reproducibility, which provide a valuable strategy for clinic diagnostics and therapeutics.

In this study, nitrogen-rich carbon dots decorated graphene oxide (N-Cdots/GO) hybrid, as a metal-free electrocatalyst for oxygen reduction reaction (ORR), is synthesized by a facile and low-cost hydrothermal treatment for the first time. Specifically, as a nitrogen-rich bridge-molecule, urea can trap free citric acid on planar planes, edges, and wrinkle sections of GO through amidation reaction in the initial stage. Then, polymer-like intermediates are in situ formed and carbonized to N-Cdots on GO. Owing to the simultaneous N-doping into both Cdots and GO characterized by XPS, as well as the formation of defective graphitic structures analyzed by Raman spectra, the as-prepared hybrid displays a remarkable electrocatalytic performance with more positive onset potential (0.13 V vs. Ag/AgCl) and high kinetic current density (up to 18.4 mA cm−2 at −0.70 V) comparable to commercial Pt/C catalyst. Furthermore, it demonstrates significantly higher catalytic efficiency (nearly 100% of four-electron ORR pathway) than those of N-Cdots or N-Cdots/GO mixture with an outstanding cyclic stability and superior methanol tolerance capability in alkaline solution.

A simple and rapid photoelectrochemical (PEC) sensor was developed for the label-free detection of a phosphoprotein (α-casein) based on a zirconium based porphyrinic metal–organic framework (MOF), PCN-222, which exhibited an enhanced photocurrent response toward dopamine under the O2-saturated aqueous media. In this work, in terms of PEC measurements and cyclic voltammetry, the PEC behaviors of PCN-222 in aqueous media were thoroughly investigated for the first time. Additionally, in the virtue of the steric hindrance effect from the coordination of the phosphate groups and inorganic Zr–O clusters as binding sites in PCN-222, this biosensor showed high sensitivity for detecting α-casein and the limit of detection (LOD) was estimated to be 0.13 μg mL–1. Moreover, the proposed method provides a promising platform for clinic diagnostic and therapeutics.

•Laponite worked as a cation exchanger for the intercalation/absorption of Co2+ ions.•Laponite-Co2+ immobilized on the surface electrode provided available Co sources for electrogenerated CoHCFe by SWV.•ITO/laponite/CoHCFe is highly stable, cost-effective and little artificial deviation.•ITO/laponite/CoHCFe showed potential in the enhanced sensing application.In this work, Co2+ ions were initially intercalated into the layers of laponite and then cobalt hexacyanoferrates (CoHCFe) were electrogenerated on the surface of laponite-Co2+ modified ITO via square wave voltammetry (SWV). At scan rate of 10 mV s−1, the electrochemical response of the ITO/laponite/CoHCFe showed two pairs of well-defined redox peaks located about 0.44 and 0.672 V vs.SCE, attributed to the redox reaction of CoII/CoIII and FeII/FeIII, respectively. The modified electrode was highly electrocatalytic to the captopril oxidation. Moreover, the ITO/laponite/CoHCFe exhibited an enhanced analytical performance for amperometric detection of captopril with two enlarged linear ranges from 3.0 × 10−7 to 1.27 × 10−4 M and 1.63 × 10−4 to 3.76 × 10−4 M and a low detection limit (0.29 μM). The modified electrode was used for electrocatalytic determination of captopril in some real samples.

A highly efficient biomimetic catalyst was fabricated based on ultrathin carbon nitride nanosheets (C3N4)-supported cobalt(II) proto-porphyrin IX (CoPPIX). The periodical pyridinic nitrogen units in C3N4 backbone could serve as electron donors for great affinity with Co2+ in PPIX, which resembled the local electronic structure as vitamin B12 and heme cofactor of hemoglobin. UV–vis kinetics and electrochemistry revealed its competitive (electro)catalysis with conventional peroxidase, while X-ray photoelectron spectroscopy and theoretical calculations suggest that the rehybridization of Co 3d with N orbitals from the backside can result in significant changes in enthalpy and charge density, which greatly promoted the activity of CoPPIX. The prepared nanocatalyst was further conjugated with streptavidin via multiple amines on the edge plane of C3N4 for facile tagging. Using biotinylated molecular beacon as the capture probe, a sensitive electrochemiluminescence-based DNA assay was developed via the electroreduction of H2O2 as the coreactant after the hairpin unfolded by the target, exhibiting linearity from 1.0 fM to 0.1 nM and a detection limit of 0.37 fM. Our results demonstrate a new paradigm to rationally design inexpensive and durable biomimics for electrochemiluminescence quenching strategy, showing great promise in bioanalytical applications.Keywords: biomimetic catalyst; carbon nitride; cobalt porphyrin; electrocatalysis; electrochemiluminescence; hydrogen peroxide

Novel multifunctional magnetic zirconium hexacyanoferrate nanoparticles (ZrHCF MNPs) were prepared, which consisted of magnetic beads (MBs) inner core and zirconium hexacyanoferrate(II) (ZrHCF) outer shell. As an artificial peroxidase, the ZrHCF MNPs exhibited remarkable electrocatalytic properties in the reduction of H2O2 at 0.2 V vs saturated calomel electrode (SCE). On the basis of the bonding interaction between Zr (IV) of the shell ZrHCF framework and phosphonate groups, the 5′-phosphorylated ssDNA probes with a consecutive stretch of guanines as a spacer could be incorporated in ZrHCF MNPs easily. Thus, DNA-grafted ZrHCF MNPs could be simply obtained by magnetic separation. The prepared nanoelectrocatalyst was further used as signal nanoprobe for the ultrasensitive electrochemical DNA assay. Under optimal conditions, the proposed biosensor presents high sensitivity for detecting target DNA with a linear range from 1.0 fM to 1.0 nM and a low detection limit of 0.43 fM. Moreover, it exhibits good performance with excellent selectivity, high stability, and acceptable fabrication reproducibility.

Early growth response protein 1 (EGR1), as a characteristic example of zinc finger proteins, acts as a transcription factor in eukaryotic cells, mediating protein–protein interactions. Here, a novel electrochemiluminescence (ECL)-based protocol for EGR1 assay was developed with a new eco-friendly emitter: singlet oxygen produced in the vicinity of nanoclay-supported zinc proto-porphyrin IX (ZnPPIX). Its electrochemical reduction stimulates an intense monochromic CL irradiation at 644 nm from the dissolved oxygen as endogenous coreactant in the aqueous solution. This ECL derivation was rationalized via hyphenated spectroscopy and theoretical calculation. To promote hydrophilicity and solid-state immobilization of porphyrins, the lamellar artificial laponite was employed as a nanocarrier owning to its large specific area without the blackbody effect. The facile exfoliation of laponite produced quality monolayered nanosheets and facilitated the adsorption and flattening of PPIX upon the surface, resulting in a highly efficient ECL emission. Based on the release of Zn2+ in zinc finger domains of EGR1 upon contact with the ECL-inactive PPIX, which was monitored by circular dichroism and UV-absorption, a sensitive Zn2+-selective electrode for the “signal-on” detection of EGR1 was prepared with a detection limit down to 0.48 pg mL–1 and a linearity over 6 orders of magnitude. The proposed porphyrin-based ECL system thus infused fresh blood into the traditional ECL family, showing great promise in bioassays of structural Zn(II) proteins and zinc finger-binding nucleotides.

Here we report a novel solid-state ECL sensor for ultrasensitive sensing of glutathione (GSH) based on ferrocyanide-ferricyanide redox couple (Fe(CN)63–/4–) induced electrochemiluminescence (ECL) amplification of carbon dots (C-dots). The electropolymerization of C-dots and (11-pyrrolyl-1-yl-undecyl) triethylammonium tetrafluoroborate (A2) enabled immobilization of the hydrophilic C-dots on the surface of glassy carbon electrode (GCE) perfectly, while the excellent conductivity of polypyrrole was exploited to accelerate electron transfer between them. The Fe(CN)63–/4– can expeditiously convert the C-dots and S2O82– to C-dot•– and SO4•–, respectively. High yields of the excited state C-dots (C-dots*) were obtained, and a ∼10-fold ECL amplification was realized. The C-dots* obtained through the recombination of electron-injected and hole-injected processes may be impeded due to the interference of GSH to K2S2O8. Therefore, the constructed sensor for GSH showed a detection limit down to 54.3 nM (S/N = 3) and a wide linear range from 0.1–1.0 μM with a correlation coefficient of 0.997.

•CuNPs are prepared by in situ electrochemical reduction of the chelated copper ions.•Electrodeposited PCV works as chelating agent for the preconcentration of Cu2+.•Electrodeposited PCV remains the redox properties.•Enhanced electrocatalysis of H2O2 is achieved due to the synergic effect.Copper nanoparticles (CuNPs) form by in situ electrochemical reduction of chelated copper ions on the electrode with pyrocatechol violet (PCV) and single walled carbon nanotubes (SWCNTs). The electrodeposited PCV is used as chelating agent for copper ions as well as the redox mediator during the electrocatalysis of H2O2. Due to the synergic effect of SWCNTs/PCV/CuNPs, the modified electrode gives enhanced analytical performance for detection of H2O2 at −0.2 V vs. SCE with an enlarged linear response as a function of peroxide concentration spanning 2 × 10−6 to 1.2 × 10−2 M.

•Amphiphilic surfactant derived from pyrrole was used to construct a special microheterogeneous system incorporated with SWCNTs by electropolymerization.•Common redox probe, Fe(CN)63−/4−, was captured into this microheterogeneous system due to the cooperation interactions of electrostatic and π-π stacking.•A dramatically negative shift in the half wave potential compared to Fe(CN)63−/4− in aqueous solution can be obtained due to the unusual Fe(CN)63−/4− partitioning.•The entrapped Fe(CN)63−/4− was applied in the construction of the enhanced electrochemical sensor to paracetamol.An enhanced paracetamol sensor was developed based on the integrative system of single walled carbon nanotubes (SWCNTs) and the pyrrolic surfactant, (11-pyrrolyl-1-yl-undecyl)triethylammonium tetrafluoroborate (A2), in which confined the redox probe, Fe(CN)63−/4−. A well-defined redox peaks of the firmly confined Fe(CN)63−/4− with dramatically negative shift in the half-wave potential compared to Fe(CN)63−/4− in aqueous solution was observed at GCE/polyA2-Fe(CN)63−/4−/SWCNTs. To understand the unusual Fe(CN)63−/4− partitioning in this microheterogeneous system, the responses of the Fe(CN)63−/4− at the electrodes modified by SWCNTs, polyA2, SWCNTs/polyA2, and polyA2/SWCNTs were investigated, respectively. The results of cyclic voltammetry (CV) and differential pulse voltammetry (DPV) indicated that the proposed electrode exhibiting efficient electrocatalytic capability towards the paracetamol oxidation. Thereafter, an amperometric assay for paracetamol at GCE/polyA2-Fe(CN)63−/4−/SWCNTs was developed at 0.4 V with an enhanced linear range from 3.4×10−7∼7.98 × 10−4 M.

The pursuit of more specific and sensitive response is a perpetual goal for modern bioassays. This work proposed a novel label-free strategy about redox-related mass effect based on the surface plasmon resonance (SPR) technique for ultrasensitive determination of DNA. The protocol starts with the modification of SPR gilded disk with the capture DNA (cDNA). After the conjugation of immobilized cDNA with the target DNA (tDNA), the hybridization chain reaction was triggered by the introduction of mutual partial complementary primers to elongate the terminal into a nanoscale duplex. As it is reported that porphyrin could intercalate into the grooves of the double-stranded DNA (dsDNA) scaffold, multiple positive-charged FeIIImeso-tetra(N-methyl-4-pyridyl) porphine (FeTMPyP) with symmetric structure were uptaken for in situ formation of porphyrin-dsDNA complex. Given FeTMPyP a highly efficient catalysis for the peroxide reduction, its presence as a biomimetic cofactor was validated via circular dichroism and UV–vis spectroscopy, demonstrating a tight binding as well as high catalytic activity and stability. Using 4-chloro-1-naphthol as a proton donor, the catalytic reduction of H2O2 would oxidize it into insoluble benzo-4-chloro-hexadienone, which simultaneously deposited on the heterogeneous interface, leading to a significant amplification in both SPR response and topological height profile. The signal increment was proportional to the concentration of tDNA, thus an ultrasensitive SPR-based DNA assay was developed with a linear range over four orders of magnitudes and a sub-femtomolar detection limit of 0.73 fM. The developed methodology exemplifies a different way of thinking about mass-sensing modes, extending conventional SPR-based DNA analysis to relevant biomedical applications.

Herein, a special microheterogeneous system for Fe(CN)63–/4– capture was constructed based on graphene (GN) and the electropolymeric cationic surfactant, an amphiphilic pyrrole derivative, (11-pyrrolyl-1-yl-undecyl) triethylammonium tetrafluoroborate (A2). The morphology of the system was characterized by scanning electron microscope. The redox properties of the entrapped Fe(CN)63–/4– were investigated by cyclic voltammetry and UV–visible spectrometry. The entrapped Fe(CN)63–/4– exhibited highly electroactive with stable and symmetrical cyclic voltammetric signal. A dramatic negative shift in the half wave potential can be obtained due to the unusual Fe(CN)63–/4– partitioning in in this microheterogeneous system based on poly(A2+GN). Finally, the entrapped Fe(CN)63–/4– was applied in the construction of the enhanced biosensors to hydrogen peroxide and sulfide.Keywords: amphiphilic pyrrole derivative; Fe(CN)63−/4− partitioning; graphene; inhibition; sulfide

•The interfacial properties were studied by three different electrochemical methods.•The grafted gallic acid induced the enhanced chelating ability.•Cu anodic stripping behavior depended on the coordination environment•“Prussian blue” analogues deposited on Cu2+-chelated electrode during EIS measurements.Biocompatible gallic acid (GA) was conjugated on the shell of γ-Fe2O3 encapsulated with bio-inspired polydopamine (PDA) to form novel environment friendly magnetic nanoparticles, γ-Fe2O3/PDA/GA. To elucidate the effect of the grafted GA, γ-Fe2O3/PDA and γ-Fe2O3/PDA/GA were used to modified electrodes. Cyclic voltammetry (CV), square wave anodic stripping voltammetry (SWASV) and electrochemical impedance spectroscopy (EIS) were adopted to comparatively study their interfacial properties, their chelating abilities and their electrochemical responses to Cu2+ and Pb2+.

A novel QD with near-infrared (NIR) electrochemiluminescence (ECL) emission was prepared electrolytically by hydrodynamic chronopotentiometry, using Unithiol, a clinically-known metalantidote, as the capping agent for the fabrication of an ultrasensitive ion-selective microchip. The proposed synthetic route as well as the optical properties of QD was clarified with both morphological and spectroscopic characterization. In air-saturated pH 8.0 phosphate buffer with dissolved oxygen as the endogenous coreactant, an intensive NIR-ECL emission at 692 nm arose which was ascribed to the unique surface states of multidentate-chelated QDs. By tuning electrolytes, a low-potential ECL peaking at −0.79 V (vs. Ag/AgCl) could further be achieved. Based on the validated competition of heavy metallic cations with the stabilizer Unithiol as it stabilizes the aqueous dispersion of QDs, the ECL emission could be significantly quenched and a home-made ECL ion-selective chip was manufactured. It was further found that capping with a cation exchange membrane enabled accelerated adsorption of metal ions and sensitized the ECL signal. Using cupric cations as a model analyte, the devised sensor showed a linear range from 10.0 pM to 1.0 mM with a detection limit down to 6.7 pM, and was successfully used in the direct detection of a Bordeaux mixture with an inorganic pesticide residue on the grape skin with high accuracy and selectivity. The proposed strategy could also be extended to quantify Hg2+ and Pb2+ with stronger thiol-bonding capability than Cd2+. The developed microsensing system with replicable one-step synthesis should facilitate portable and integrated QD-based NIR-ECL applications for food hygiene inspection and environmental monitoring.

A novel self-assembled glucose biosensor based on graphene oxide (GO) was constructed by using 1-pyrenebutyric acid–N-hydroxysuccinimide ester (PANHS) as linking molecular. The stepwise self-assembly process was performed for PANHS anchoring in N,N-dimethylformamide (DMF) solvent and the further glucose oxidase (GOD) binding in aqueous solution, respectively. The molecular interactions and the morphologic properties were characterized by Fourier transform infrared spectroscopy (FTIR), field emission scanning electronic microscopy (FESEM), and atomic force microscopy (AFM). In addition, the quantitative loadings of anchored PANHS and GOD were well elucidated by surface plasmon resonance (SPR) measurements. The obtained novel glucose sensor exhibited satisfactory analytical performance to glucose: wide linear range (4.0 × 10−6 to 4.4 × 10−3 M), fast response (10 s), high sensitivity (40.5 ± 0.4 mA M−1 cm−2), and low detection limit (2 μM, S/N = 3). Furthermore, the biosensor exhibited excellent long-term stability and satisfactory reproducibility.

•A novel NADH and ethanol sensor was constructed based on PCV electrodeposited on SWCNTs modified GCE.•The electrochemical detection of NADH and ethanol was applied at low potential.•The synergic effect of PCV and SWCNTs resulted in the sensor surface of high hydrophilicity and the fast electron transfer.•Three-dimensional network of SWCNTs improves the surface coverage of PCV.In this work, the electrodeposition of pyrocatechol violet (PCV) was initially investigated by the electrochemical surface plasmon resonance (ESPR) technique. Subsequently, PCV was used as redox-mediator and was electrodeposited on the surface of pencil graphite electrode (PGE) modified with single-wall carbon nanotubes (SWCNTs). Owing to the remarkable synergistic effect of SWCNTs and PCV, PGE/SWCNTs/PCV exhibited excellent electrocatalytic activity towards dihydronicotinamide adenine dinucleotide (NADH) oxidation at low potential (0.2 V vs. SCE) with fast amperometric response (<10 s), broad linear range (1.3–280 μM), good sensitivity (146.2 μA mM−1 cm−2) and low detection limit (1.3 μM) at signal-to-noise ratio of 3. Thus, this PGE/SWCNTs/PCV could be further used to fabricate a sensitive and economic ethanol biosensor using alcohol dehydrogenase (ADH) via a glutaraldehyde/BSA cross-linking procedure.

A glassy carbon electrode (GCE) was modified with pyrocatechol violet (PCV) that was electrodeposited on single walled carbon nanotubes (SWCNTs) via continuous cycling between 0 and 0.9 V (vs. SCE). The resulting electrode exhibits excellent electrocatalytic activity towards the oxidation of hydrazine at 0.3 V. The apparent surface coverage of the electrode is at least 24 times higher (2.7 × 10−10 mol cm−2) than that obtained with a bare GCE (1.1 × 10−11 mol cm−2). This is attributed to a remarkably strong synergistic effect between the acid-pretreated SWCNTs and the electrodeposited PCV coating. Response is fast (2 s) and sensitive (281 mA M−1 cm−2). Other features include a wide linear range (150 nM to 0.4 mM) and a low detection limit (150 nM at an SNR of 3). The sensor has been successfully applied to the determination of hydrazine in water and cigarette samples with good accuracy and precision. In addition, the morphology and the wetting properties of the coating were studied by scanning electromicroscopy and contact angle measurements.

•The reduction and surface function of graphene oxide were simultaneously achieved by dopamine.•The bioinspired surface was further used as a support to anchor active gold nanoparticles.•The residue moiety of catechol in hybrid system can efficiently accelerate the electron transfer.•The hybrid system is of simple ingredients and possesses high catalytic properties to NADH and results in high performance ethanol biosensor.We report here an efficient approach to enhance the performance of biosensing platform based on graphene or graphene derivate. Initially, graphene oxides (GO) nanosheets were reduced and surface functionalized by one-step oxidative polymerization of dopamine in basic solution at environment friendly condition to obtain the polydopamine (Pdop) modified reduced graphene oxides (PDRGO). The bioinspired surface was further used as a support to anchor active gold nanoparticles (AuNPs). The morphology and structure of the as-prepared AuNPs/PDRGO nanocomposite were investigated by field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Fourier transform-infrared spectroscopy (FT-IR). Electrochemical studies demonstrate that the as-prepared AuNPs/PDRGO hybrid materials possess excellent electrochemical properties and electrocatalytic activity toward the oxidation of NADH at low potential (0.1 V vs. SCE) with the fast response (15 s) and the broad linear range (5.0×10−8–4.2×10−5 M). Thus, this AuNPs/PDRGO nanocomposite can be further used to fabricate a sensitive alcohol biosensor using alcohol dehydrogenase (ADH), by simply incorporating the specific enzyme within the composite matrix with the aid of chitosan (Chit).

In this work, three protocols were performed to incorporate gold nanoparticles (AuNPs) into electrospun nanofibers of poly(acrylonitrile-co-acrylic acid) (PAN-co-PAA), namely, (1) direct electrospinning AuNPs/PAN-co-PAA/DMF colloid solution, (2) in situ reduction of the chelated Au ions in the electrospun gold salt/PAN-co-PAA nanofibers by NaBH4, and (3) further electroless-plating of the in situ reduced AuNPs-loaded nanofibers. The morphologies of the AuNPs-loaded nanofibers were characterized by the field emission scanning electron microscopy (FE-SEM) and the transmission electron microscopy (TEM). As prepared AuNPs-loaded nanofibers were used to immobilize tris(2,2′-bipyridyl)ruthenium(II) [Ru(bpy)3]2+, to form the ECL sensors. The results demonstrated that the dramatically enhanced solid-state electrochemical and ECL performance could be feasibly achieved by the incorporation of AuNPs into the nanofibers. Moreover, the enhanced effect depended on the AuNPs assembly method, which resulted in the different electroconductive and catalytic abilities.