Electrode processes on an enzyme embodied electrode

Abstract

An enzyme embodied electrode (EEE) is an electrochemical biosensing device fabricated by direct immobilization of enzyme on a platinized electrode. In order to elucidate the reaction scheme of an EEE, the pulse voltammetric technique was employed, in which a potentiostatic pulse was applied after the preoxidation pulse and the following open circuit period, sequentially. A reaction scheme was proposed by taking substrate and product diffusion in the micropores of platinum black into account, besides the enzymatic and electrochemical reactions. During the open circuit period the concentration profile of hydrogen peroxide was assumed to reach a steady state when the production of hydrogen peroxide equilibrated with the diffusion at the microporous electrode. Assuming a steady state concentration profile at the balanced state, an appropriate solution was deduced for a differential equation that expresses enzymatic production, electrochemical oxidation and diffusion of hydrogen peroxide to bulk solution. This expression explained well the observed transient current that decayed exponentially and the proportionality to the glucose concentration.