High Redox Potential Cathode Based on Laccase Covalently Attached to Gold Electrode

A new strategy for oriented covalent immobilization of Trametes hirsuta laccase on gold electrodes is presented. The strategy is based on the gold surface modification with a mixed monolayer of an aromatic diazonium salt derivative and 6-mercapto-1-hexanol for further use as scaffold for the enzyme's covalent linkage. This strategy offers a variety of advantages such as high stability and laccase-friendly support morphology, which turns it into a suitable metal enzyme interface. Conditions aiming at optimum orientation for direct electron transfer (DET) via the T1 copper site were studied. Current density values up to 40 mu A.cm(-2) were measured for the electrocatalytic reduction of O-2 in the absence of redox mediators. This strategy is a big step forward in the development of laccase-modified gold electrodes for bioelectrocatalytic reduction of O-2.