Bioelectrocatalytic reduction of O2 at a supramolecularly associated laccase electrode

In order to improve the bioelectrocatalytic reduction of dioxygen, a method for the supramolecular immobilization of Trametes versicolor laccase is reported. The immobilization support consisted of a self-assembled monolayer (SAM) of mercaptoundecanoic acid tyrosine amide on gold electrodes. To mediate the electron transfer between the enzyme and the electrode surface, ferrocenehexanethiol was introduced into the SAM as a second component. The resulting system was studied by cyclic voltammetry. Reduction of dioxygen started at 0.80 V, with a reduction peak at 0.52 V and a decrease in its intensity was observed when the solution was deaerated. The achieved current density for dioxygen reduction (23 mu A cm(-2), open to air) suggests a high surface density of active enzyme prone to bioelectrocatalytic activity. This system offers new insights into the supramolecular design of biofuel cells.