EQCM Studies on Enzymatic Specific Activities of Glucose Oxidase Adsorbed on Au-electroplated and Carbon Nanotubes-modified Au Electrodes

Abstract

The electrochemical quartz crystal microbalance (EQCM) technique was employed to monitor in situ the adsorption of glucose oxidase (GOD) onto bare Au, Au-electroplated, and carbon nanotubes(CNTs)-modified Au electrodes. The enzymatic specific activities (ESAi) for GOD adsorbed on various surfaces were measured from the mass of adsorbed GOD obtained via EQCM characterization and the charge for oxidation of enzymatically generated H2O2. The results showed that GOD could adsorb on the investigated surfaces with different adsorption amounts, and the adsorbed GOD was enzymatically active to some degree; the modification of CNTs increased the adsorption amount of GOD and the response current to glucose, but the ESAi decreased with the increase of the amount of modified CNTs; the Au electroplating on Au electrode also increased the response current to glucose, but the ESAi changed little after the electroplating.