Direct Electron Transfer Reactivity of Glucose Oxidase on Electrodes Modified With Zirconium Dioxide Nanoparticles

The direct electron transfer between electrodes and glucose oxidase (GOD) immobilized in a matrix containing zirconium dioxide nanoparticles (ZrO₂) is described. The protein-nanoparticle assembly is stabilized by charged and uncharged compounds and the direct electron transfer is enhanced. The effects of different compositions on the electrochemical parameters, formal potential, surface loading, and constant heterogeneous electron transfer rate are characterized with cyclic voltammetry. The fastest electron transfer rate with the smallest deviation of the is obtained when GOD is immobilized with ZrO₂ nanoparticles, colloidal platinum and poly-Lysine (PLL). Incorporation of charged compounds for immobilization of GOD causes a larger positive shift of the formal potential. Electrochemical and spectroscopic measurements show that the GOD entrapped in ZrO₂/Pt-PLL or ZrO₂/Pt-PVA film retains its bioactivity efficiently and exhibits excellent electrocatalytic behavior towards glucose. No enzymatic activity of the immobilized GOD can be observed on ZrO₂/DMSO and ZrO₂/DDAB film.