Fangxin Hu

Electrochemical sensing of hydrogen peroxide using metal nanoparticles: a review

AbstractWe are reviewing the state of electrochemical sensing of H2O2 based on the use of metal nanoparticles. The article is divided into subsections on sensors based on nanoparticles made from Ag, Pt, Pd, Cu, bimetallic nanoparticles and other metals. Some sensors display high sensitivity, fast response, and good stability. The review is subdivided into sections on sensors based on heme proteins and on nonenzymatic sensors. We also discussed the challenges of nanoscaled sensors and their future aspects. FigureSensing mechanism of (A) mediator-based enzyme biosensor, (B) mediator-less enzyme biosensor and (C) nonenzymatic sensors with metal nanoparticles for the electrocatalytic reduction toward H2O2

Study on the application of reduced graphene oxide and multiwall carbon nanotubes hybrid materials for simultaneous determination of catechol, hydroquinone, p-cresol and nitrite

In this paper, the reduced graphene oxide and multiwall carbon nanotubes hybrid materials (RGO-MWNTs) were prepared and a strategy for detecting environmental contaminations was proposed on the basis of RGO-MWNTs modified electrode. The hybrid materials were characterized by the scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and N(2) sorption-desorption isotherms. Due to the excellent catalytic activity, enhanced electrical conductivity and high surface area of the RGO-MWNTs, the simultaneous measurement of hydroquinone (HQ), catechol (CC), p-cresol (PC) and nitrite (NO(2)(-)) with four well-separate peaks was achieved at the RGO-MWNTs modified electrode. The linear response ranges for HQ, CC, PC and NO(2)(-) were 8.0-391.0 μM, 5.5-540.0 μM, 5.0-430.0 μM and 75.0-6060.0 μM, correspondingly, and the detection limits (S/N=3) were 2.6 μM, 1.8 μM, 1.6 μM and 25.0 μM, respectively. The outstanding film forming ability of RGO-MWNTs hybrid materials endowed the modified electrode enhanced stability. Furthermore, the fabricated sensor was applied for the simultaneous determination of HQ, CC, PC and NO(2)(-) in the river water sample.

Simultaneous determination of ascorbic acid, dopamine, uric acid and tryptophan on gold nanoparticles/overoxidized-polyimidazole composite modified glassy carbon electrode

A novel electrode was developed through electrodepositing gold nanoparticles (GNPs) on overoxidized-polyimidazole (PImox) film modified glassy carbon electrode (GCE). The combination of GNPs and the PImox film endowed the GNPs/PImox/GCE with good biological compatibility, high selectivity and sensitivity and excellent electrochemical catalytic activities towards ascorbic acid (AA), dopamine (DA), uric acid (UA) and tryptophan (Trp). In the fourfold co-existence system, the peak separations between AA-DA, DA-UA and UA-Trp were large up to 186, 165 and 285 mV, respectively. The calibration curves for AA, DA and UA were obtained in the range of 210.0-1010.0 μM, 5.0-268.0 μM and 6.0-486.0 μM with detection limits (S/N=3) of 2.0 μM, 0.08 μM and 0.5 μM, respectively. Two linear calibrations for Trp were obtained over ranges of 3.0-34.0 μM and 84.0-464.0 μM with detection limit (S/N=3) of 0.7 μM. In addition, the modified electrode was applied to detect AA, DA, UA and Trp in samples using standard addition method with satisfactory results.

Au-nanoclusters incorporated 3-amino-5-mercapto-1,2,4-triazole film modified electrode for the simultaneous determination of ascorbic acid, dopamine, uric acid and nitrite.

A novel biosensor has been constructed by the electrodeposition of Au-nanoclusters (nano-Au) on poly(3-amino-5-mercapto-1,2,4-triazole) (p-TA) film modified glassy carbon electrode (GCE) and employed for the simultaneous determination of dopamine (DA), ascorbic acid (AA), uric acid (UA) and nitrite (NO(2)(-)). NH(2) and SH groups exposed to the p-TA layer are helpful for the electrodeposition of nano-Au. The combination of nano-Au and p-TA endow the biosensor with large surface area, good biological compatibility, electricity and stability, high selectivity and sensitivity and flexible and controllable electrodeposition process. In the fourfold co-existence system, the linear calibration plots for AA, DA, UA and NO(2)(-) were obtained over the range of 2.1-50.1 μM, 0.6-340.0 μM, 1.6-110.0 μM and 15.9-277.0 μM with detection limits of 1.1×10(-6) M, 5.0×10(-8) M, 8.0×10(-8) M and 8.9×10(-7) M, respectively. In addition, the modified biosensor was applied to the determination of AA, DA, UA and NO(2)(-) in urine and serum samples by using standard adding method with satisfactory results.

Multi-wall carbon nanotube-polyaniline biosensor based on lectin-carbohydrate affinity for ultrasensitive detection of Con A.

In this paper, a novel method for detecting concanavalin A (Con A) was developed based on lectin-carbohydrate biospecific interactions. Multi-wall carbon nanotube-polyaniline (MWNT-PANI) nanocomposites, synthesized by in situ polymerization, were chosen to immobilize d-glucose through the Schiff-base reaction. The immobilized D-glucose showed high binding sensitivity and excellent selectivity to its target lectin, Con A. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), transmission electron microscopy (TEM) and atomic force microscopy (AFM) were applied to characterize the assembly process of the modified electrode. Due to the high affinity of Con A for D-glucose and high stability of the propounded sensing platform, the fabricated biosensor achieved ultrasensitive detection of Con A with good sensitivity, acceptable reproducibility and stability. The changes of response current were proportional to the Con A concentrations from 3.3 pM to 9.3 nM, with a detection limit of 1.0 pM. Therefore, the combination of MWNT-PANI nanocomposites and the special binding force between lectin and carbohydrate provides an efficient and promising platform for the fabrication of bioelectrochemical devices.

Highly-sensitive cholesterol biosensor based on platinum–gold hybrid functionalized ZnO nanorods

A novel scheme for the fabrication of gold/platinum hybrid functionalized ZnO nanorods (Pt-Au@ZnONRs) and multiwalled carbon nanotubes (MWCNTs) modified electrode is presented and its application for cholesterol biosensor is investigated. Firstly, Pt-Au@ZnONRs was prepared by the method of chemical synthesis. Then, the Pt-Au@ZnONRs suspension was dropped on the MWCNTs modified glass carbon electrode, and followed with cholesterol oxidase (ChOx) immobilization by the adsorbing interaction between the nano-material and ChOx as well as the electrostatic interaction between ZnONRs and ChOx molecules. The combination of MWCNTs and Pt-Au@ZnONRs provided a favorable environment for ChOx and resulted in the enhanced analytical response of the biosensor. The resulted biosensor exhibited a linear response to cholesterol in the wide range of 0.1-759.3 μM with a low detection limit of 0.03 μM and a high sensitivity of 26.8 μA mM(-1). The calculated apparent Michaelis constant K(M)(app) was 1.84 mM, indicating a high affinity between ChOx and cholesterol.

Simultaneous determination of hydroquinone, catechol, resorcinol and nitrite using gold nanoparticles loaded on poly-3-amino-5-mercapto-1,2,4-triazole-MWNTs film modified electrode

A simple and highly sensitive electrochemical method has been developed for the simultaneous determination of hydroquinone (HQ), catechol (CC), resorcinol (RC) and nitrite (NO2−). The electrode in this study exhibited high selectivity, well stability and reproducibility and good compatibility.