Yizhe Wang

A sensitive NADH and glucose biosensor tuned by visible light based on thionine bridged carbon nanotubes and gold nanoparticles multilayer

A NADH and glucose biosensor based on thionine cross-linked multiwalled carbon nanotubes (MWNTs) and Au nanoparticles (Au NPs) multilayer functionalized indium-doped tin oxide (ITO) electrode were presented in this paper. The effect of light irradiation on the enhancement of bioelectrocatalytic processes of the biocatalytic systems by the photovoltaic effect was investigated. This bioelectrode exhibited excellent catalytic activity of the oxidation towards dihydronicotinamide adenine dinucleotide (NADH). Most interesting, the performance of this NADH sensor could be tuned by the visible light. When the biosensor was performed in the dark, the anodic current increased linearly with NADH concentration over the range from 0.5 to 237 microM with detection limit 0.1 microM and sensitivity 17 nA microM(-1). The sensitivity became 115 nA microM(-1) with detection limit 0.05 microM with the light irradiation. Compared with the reaction in dark, the sensitivity increased around 7 folds while the detection limit decreased 2 folds. The glucose biosensor also exhibited the same behavior. The linear range was from 10 microM to 2.56 mM with the sensitivity of 7.8 microAmM(-1) and detection limit 5.0 microM in the dark. After the light irradiation, the linear range was from 1 microM to 3.25 mM with the sensitivity of 18.5 microA mM(-1) and detection limit 0.7 microM. It indicated a potential to provide an operational access to develop new kinds of photocontrolled dehydrogenase enzyme-based bioelectronics.

Bifunctional nanocatalyst of bimetallic nanoparticle/TiO2 with enhanced performance in electrochemical and photoelectrochemical applications.

A novel metal/semiconductor hybrid nanostructure with enhanced catalytic functions has been prepared by a simple self-assembly approach. This new bifunctional nanocatalyst consists of evenly dispersed Au/Pt hybrid nanoparticles (Au/Pt NPs) assembled on NH(2) group functionalized anatase TiO(2) colloid spheres with nanoporous surface (f-TiO(2)). The resulting bimetallic nanoparticles/TiO(2) (noted as f-TiO(2)-Au/Pt NPs) hybrid nanostructure is characterized by various methods and expected as a promising catalyst in electrochemical and photoelectrochemical applications because of its satisfactory or even enhanced catalytic properties from both TiO(2) and Au/Pt NPs. Compared with the f-TiO(2), the electrochemical results indicate that the as-prepared f-TiO(2)-Au/Pt NPs exhibited more prominent electrocatalytic reduction toward hydrogen peroxide at low potential, which was then used as a sensitive sensor with a detection limit of 75 nM. Most importantly, the present hybrid material has the better photocatalytic property, as demonstrated by the photoelectrochemical catalysis of glucose.

Surface plasmon resonance and electrochemistry characterization of layer-by-layer self-assembled DNA and Zr4+ thin films, and their interaction with cytochrome c

Through electrostatic layer-by-layer (LbL) assembly, negatively charged calf thymus double stranded DNA (CTds-DNA), and positively charged Zr4+ ions were alternately deposited on gold substrate modified with chemisorbed cysteamine. Thus-prepared three-dimensional DNA networks were characterized by surface plasmon resonance (SPR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and infrared reflection-absorption spectroscopy (IR-RAS). SPR spectroscopy indicates that the effective thickness of DNA monolayer in the (DNA/Zr4+)(1) bilayer was 1.5+/-0.1 nm, which corresponds to the surface coverage of 79% of its full packed monolayer. At the same time, a linear increase of film thickness with increasing number of layers was also confirmed by SPR characterizations. The data of XPS and IR-RAS show that Zr4+ ions interact with both the phosphate groups and nitrogenous bases of DNA and load into the framework of DNA. Furthermore, the interactions between this composite film and heme protein cytochrome c (Cyt c) were investigated by SPR spectroscopy and electrochemistry. Compared with the adsorption of Cyt c on DNA monolayer, this composite multilayer film can obviously enhance the amount of immobilized Cyt c confirmed by SPR reflectivity-incident angle (R-theta) curves. Cyclic voltammetry (CV) indicates the Cyt c adsorbed on the composite film is electroactive, and the enhancement of peak current in CV indirectly verifies the increase of the amount of immobilized Cyt c.

Toxicity detection in water containing heavy metal ions with a self-powered microbial fuel cell-based biosensor

In this work, a self-powered microbial fuel cell (MFC)-based biosensor was developed for detecting toxicity in water containing heavy metal ions. Experimental conditions containing concentration of potassium ferricyanide, load resistor and glucose concentration were optimized. Six heavy metal ions (2mg/L, Cu2+, Hg2+, Zn2+, Cd2+, Pb2+ and Cr3+) were tested by this biosensor and the inhibition ratios obtained were 12.56%, 13.99%, 8.81%, 9.29%, 5.59% and 1.95%, respectively. The inhibition ratios of 28.13% was also obtained for detecting the laboratory wastewater containing several heavy metal ions. The experimental results exhibited the feasibility and potential of the self-powered biosensor in detecting toxicities in water containing heavy metal ions.

Small Microbial Three-Electrode Cell Based Biosensor for Online Detection of Acute Water Toxicity

The monitoring of toxicity of water is very important to estimate the safety of drinking water and the level of water pollution. Herein, a small microbial three-electrode cell (M3C) biosensor filled with polystyrene particles was proposed for online monitoring of the acute water toxicity. The peak current of the biosensor related with the performance of the bioanode was regarded as the toxicity indicator, and thus the acute water toxicity could be determined in terms of inhibition ratio by comparing the peak current obtained with water sample to that obtained with nontoxic standard water. The incorporation of polystyrene particles in the electrochemical cell not only reduced the volume of the samples used, but also improved the sensitivity of the biosensor. Experimental conditions including washing time with PBS and the concentration of sodium acetate solution were optimized. The stability of the M3C biosensor under optimal conditions was also investigated. The M3C biosensor was further examined by formaldehyde at the concentration of 0.01%, 0.03%, and 0.05% (v/v), and the corresponding inhibition ratios were 14.6%, 21.6%, and 36.4%, respectively. This work provides a new insight into the development of an online toxicity detector based on M3C biosensor.