Comparison of the direct electrochemistry of glucose oxidase immobilized on the surface of Au, CdS and ZnS nanostructures.

A comparison of the electrochemical and photoelectrochemical behaviors of three biosensors, based on the use of Au, CdS, and ZnS nanoparticles-glucose oxidase (GOD) system, is discussed. All the nanoparticles were electrodeposited onto the indium tin oxide (ITO) thin film coated glass surface. GOD was then immobilized on the nanoparticles-modified electrodes surface with the sol-gel technique. The deposited nanoparticles on ITO electrodes were characterized by scanning electron microscopy, UV-vis spectroscopy and electrochemical impedance spectra. The direct electrochemistry of GOD, analytical performance of glucose calibration curves and the kinetic parameters of the enzyme reaction were compared for all the electrochemical biosensors. Furthermore, the current response of the quantum dots-GOD system biosensor can be increased after illumination. The electrochemical and photoelectrochemical biosensors based on ZnS nanostructures exhibited higher sensitivity than that of Au or CdS nanostructures. Considering ZnS is nontoxic to human and environment, the results suggest that ZnS nanoparticles-GOD system seems to be a promising platform for fabrication of novel electrochemical and photoelectrochemical biosensors.