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

Abstract

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 µA·cm -2 were measured for the electrocatalytic reduction of O 2 in 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 .

Controlling Redox Enzyme Orientation at Planar Electrodes

“…It should be noted that a mixed layer of aromatic diazonium salt and thiol can be advantageously used, as demonstrated in the case of LAC on gold electrodes. A submonolayer of aryl groups was formed to minimize multilayer formation by aryl radical attack, while full electrode coverage was achieved by further thiol adsorption [114].…”

Biohydrogen for a New Generation of H2/O2 Biofuel Cells: A Sustainable Energy Perspective

“…[187] SAM-functionalized gold electrodes and gold nanoparticles (NPs) with anthracenethiol derivatives, [188] or phenyl groups ending either with amino or carboxyl functions were also evaluated as platforms for efficient orientation of Trametes versicolor (Tv), Tt and Trametes hirsute (Th) LACs. [189][190][191] PMIRRAS, QCM, and electrochemistry were coupled and allowed a specific orientation linked to a different activity of the enzyme depending on the functionality borne by the SAM to be demonstrated. [189] The authors also demonstrated a clear correlation between the orientation of LAC with a b-sheet tilted with respect to the electrode surface and the electrocatalytic activity.…”

Laccase cathode approaches to physiological conditions by local pH acidification

“…[7] Immobilization of Lc on electrodes has allowed measuring high current densities of O2 reduction at low overpotentials under optimum conditions of its enzymatic activity, overcoming the classic chloride inhibition limitation. [8,9] Besides chloride reversible inhibition, the main drawback when considering ThLc as an appropriate cathodic biocatalyst is its acidic pH optima (which ranges from 3 to 5), being almost completely inhibited at physiological pH. To overcome that limitation several approaches can be tested.…”