Enzymatic Electrocatalysis: Controlled Potential Electrolysis and Cosubstrate Regeneration with Immobilized Enzyme Modified Electrode

Abstract

Catalytic currents obtained by coupling between electrochemical reaction and enzymatic catalysis are studied under two configurations: with the enzyme in solution, or with the enzyme immobilized onto the electrode surface. The corresponding set of differential equations, describing electrolyzing currents as a function of time, cannot be solved analytically, and a numerical method is applied to give approximate solutions. Example simulations are made with parameter values suitable for glucose oxidase as a catalyst and benzoquinone/hydroquinone as the cosubstrate redox couple. In each configuration, a quasi‐steady‐state current is obtained as the consequence of the rate balance between the enzymatic and electrochemical reactions. A comparison of efficiency between the two situations proves that direct immobilization of the catalyst on the electrode surface (enzymatic electrocatalysis) gives the best results. For example, it is shown that catalytic current is independent of mass transfer in such a case. Experimental results obtained with a reticulated vitreous carbon electrode modified (or not) by a glucose oxidase monolayer confirm this theoretical analysis.