Laccase cathode approaches to physiological conditions by local pH acidification

Abstract

A new conceptual approach to improve the performance of a laccase--based cathode at neutral pH is presented. The working pH of Trametes hirsuta laccase, typically acidic, can be achieved by oxidation of biological compounds such as glucose catalyzed by a second enzyme immobilized in the vicinity of the laccase electrode.

Comprehensive Study of the Enzymatic Catalysis of the Electrochemical Oxygen Reduction Reaction (ORR) by Immobilized Copper Efflux Oxidase (CueO) From Escherichia coli

“…The change of the onset potential as a function of the solution pH for both modified and unmodified gold electrodes is reported in Figures 6D,E . According to this figure, the onset potential of both electrodes moves to lower values with an average of 54 mV per pH unit when pH increases from 3.0 to 7.0, in accordance with previous studies of this or similar enzymes (Otsuka et al, 2007 ; Weigel et al, 2007 ; Tsujimura et al, 2008 ; Miura et al, 2009 ; Clot et al, 2012 ; Filip and Tkac, 2014 ). However, the diminution of the onset potential becomes < 54 mV per pH unit for pH values higher than 6.0.…”

One-year stability for a glucose/oxygen biofuel cell combined with pH reactivation of the laccase/carbon nanotube biocathode

“…Despite the need of a laccase reactivation step at low pH, this work demonstrates the accessibility to a significant amount of power from a glucose/oxygen biofuel cell during one year. The continuous research, that especially involves the finding of novel stable enzymes for oxygen reduction at neutral pH in physiological conditions [21] or the use of local pH modification techniques [22], will certainly extend power delivery under continuous operation for in vivo applications.…”

O2Reduction in Enzymatic Biofuel Cells

“…All these engineered enzymes have yet to be tested in electrochemistry. Pita, De Lacey et al 171 proposed a different approach. By locally acidifying the pH at pH 5 near a modified electrode with Th-laccase, the authors succeeded in keeping the enzyme active while the pH of the bulk solution was 6.5.…”