Construction And Application, No Enzyme Sensor Based On Gold And Silver Metal Nanomaterials

With the rapid application and development of novel nanomaterials in electro- chemical biosensors, nano-metal electrochemical biosensor without the involvement of enzyme is becoming a hot topic. As well known, Enzyme analysis is the widely used electrochemical method to detect biological molecules, with the virtue of quick response and high specificity. In 1962, Prof.Clark(USA)firstly designed the biological chemical sensors based on modified glucose oxidase. Through more than 40 years development, its'some disadvantages (such as, the used enzyme is strongly affected by temperature leading to easy inactivation; the influence of oxygen in the sample) greatly limited the practical applications. To address these problems, metal nanomaterials fabricated electrochemical sensors without enzyme are attracting more and more attention.Employing the size effect, interface effect and quantum effect of metallic nanomaterials, one could develop novel biological electrochemical sensors based on them. On one hand, due to the large specific area and plenty of functional groups, nanomaterials could give rise to particular electrochemical catalytic effects on biological molecules; On the other hand, nanomaterials could also bring down potential in order to enhance the rate of electrochemical reaction, and the electrode selectivity and sensitivity, etc. According to the above-mentioned characteristics, in this work, we fabricated metal nanomaterials free-enzyme sensors based on gold and silver nanoparticles, mainly discussed the detection on nitrite and hydrogen peroxide, and explored the separation and detection of dopamine and ascorbic acid.1 Layer-by-layer construction of multi-walled carbon nanotubes, zinc oxide, and gold nanoparticles integrated composite electrode for nitrite detection.we have successfully fabricated an electrochemical nitrite sensor based on layer- by-layer electrodeposition of Au nanoparticles and ZnO thin film onto GC supported MWCNTs electrode. Prior deposition of ZnO thin film onto MWCNTs provides the effective substrate for uniform deposition of Au nanoparticles. The synergy effect of Au nanoparticles, ZnO thin film and MWCNTs contributed to the excellent electrochemical response towards the nitrite oxidation. The as-prepared electrode in one hand demonstrated its high stability, good reproducibility and high selectivity for the nitrite detection, while in the other hand showed its promising potential to be used for field measurements in authentic sample matrices.2 Selective detection of dopamine based on the unique property of Au– Ni alloy electrode.In this experience,the Au–Ni alloy modified GCE was prepared by Circulation voltammetric method,Differential pulse voltammetry (DPV) techniques were used to investigate the electrochemical behavior of DA in the presence of ascorbic acid (AA) . We investigated the electrochemical behavior of AA and DA on the surface of the electrode.Founded that the obtained electrode was applied in selective detection of dopamine (DA) in the presence of ascorbic acid (AA) at near neutral pH. The linear range for DA was5×10^-7—1×10^-4M. The electrode also shows good stability during detection.3 Electroderoughened silver nanodendrites DVD electrode with strongly enh- anced electrocatalytic activity toward hydrogen peroxidewe demonstrate a facile Multi-Potential steps method on the surface of DVD toward dendritic silver nanostructures directly in 0.2M pH = 7 PBS solution in the absence of protective agents. This kind of tree-like structures showed maximal electrocatalytic ability for the reduction of H₂O₂. The resulting sensor exhibited an extremely fast amperometric response, a low detection limit, and a wide linear range of detection for H₂O₂. In conclusion, we have used a simple and rapid electrochemical route to prepare a fast, low-cost and throwaway sensor for detecting hydrogen peroxide.