Effect of both electrode material and polymer configuration on the performance of the electro-chemical sensor based immobilized enzyme electrode

Surfaces of glassy carbon (GC), platinum (Pt), and gold (Au) rotating-disc electrodes have been modified to study the activity of the entrapped enzyme in special environments. The modification process involved oxidative electro-polymerization of N-methyl pyrrole, N-methyl aniline, and 8-Hydroxyquinaldine monomers in 0.2 M phosphate buffer (pH=7) containing glucose oxidase (GOx). The catalytic reactions between the electrode material and/or the entrapped enzyme in the modified electrode assembly and DL-glucose were monitored by means of a potentiostatic current-time technique in an air-saturated phosphate buffer. A linear relationship between the current and the concentration of DL-glucose, within the concentration range studied, up to approximate to 1.2 mM, was obtained. A modified GC electrode showed less sensitivity than those of metallic Au and Pt. Immobilization of GOx, which altered electrode sensitivity, improved the electrode responses at higher glucose concentrations. These results suggest that the observed electrochemical signals of the modified metallic electrodes were not only due to immobilized GOx.