Bioelectrochemical Research Based On Zinc Surlfide Nanomaterials And Its Composites

Biosensors recently have attracted greatly attention. Biosensors are one of the mostactive areas among the electrochemical analysis and bio-technological research whichpossess a couple of advantages, such as high sensitivity and accuracy, low detectionlimit, cheap, satisfactory stability, fast online monitoring in a complex system and so on.The biosensors are widely used in the basic research, biotechnology, chemistry and inthe field of diagnostics, agricultural, chemical analysis, environmental monitoring andprotection. Direct electron transfer (DET) of the enzyme could hardly achieve on thebare electrode surface. This is because the active centers of the enzyme are deeplyembedded in an insulated protective protein shell, which increased the distance betweenthe centers and the electrode surface. The introduction of innovative nanomaterials,such as metal nanoparticles, carbon nanotube and quantum dots, could effectivelyimmobilize the biological molecules and boost the DET between the redox centers andthe electrode. Nanomaterials substantially improve the catalytic activity of theimmobilized enzyme and increase the current response sensitivity. This thesis concernstwo research sections:First section, ZnS nanoparticles are electrodeposited on the ITO surface and theScan Electron Microscope (SEM), Electrochemical Impedance Spectroscopy (EIS) andCyclic Voltammetry (CV) are employed to characterize the resulting ZnS. Glucoseoxidase (GOD) is then immobilized on the modified electrode surface by the sol-gel(SG) technology. The electrochemical behaviors of GOD-SG/ZnS/ITO andGOD-SG/CdS/ITO are compared. The results indicated that the GOD-SG/ZnS/ITOelectrode was more sensitive to glucose and the linear range was0.2-5.5mM. It suggeststhat ZnS nanoparticles seem to be a promising platform in the fabrication of novelbiosensors for substituent of toxic CdE.Second section, electrodeposition is applied to prepare the ZnS–Au core-shellstructure. AuNPs are firstly deposited on the ITO surface and then ZnS (shell) are further deposited on AuNPs-modified ITO. Glucose oxidase (GOD) is then immobilizedon the modified electrode surface by the sol-gel (SG) technology. The SEM, EIS andCV are employed to characterize ZnS/AuNPs composites. The existence of thesynergistic in the ZnS/AuNPs modified electrode increases the redox peak current,which is higher than that of the individual ZnS and AuNPs nanoparticls and even largerthan the sum of the two. The linear range of GOD-SG/AuNPs/ZnS/ITO electrode is0.1-8.0mM. More important, the ZnS-AuNPs synergies can be applied to otherbiosensors.