Département de chimie moléculaire

The fabrication of a tyrosinase bioelectrode by mech. compression of a MWCNT enzyme mixt. is reported. Cyclic voltammetry of the nanostructured bioelectrode demonstrated a direct electron transfer (DET) process between tyrosinase, a copper enzyme, and MWCNT. The latter led to an enzyme redox potential of + 0.30 V vs. SCE, close to the redox potential described for the T3 binuclear copper center. Furthermore, a bioelectrocatalytic redn. of oxygen performed by tyrosinase directly wired within the MWCNT disk was demonstrated for the first time. A max. c.d. of 0.55 mA cm- 2 was recorded by chronoamperometric measurements at 0 V vs. SCE. The bioelectrode exhibits excellent stability over time, conserving more than 50{%} of its activity after one week. DET between MWCNTs and the T3 binuclear copper centers have been further investigated by studying the influence of two tyrosinase inhibitors: benzoic acid and cyanide. As previously reported for blue multi-copper oxidases, such as bilirubin oxidase and laccase, tyrosinase can achieve oxygen redn. via DET between MWCNT and its T3 binuclear copper center, representing an alternative in the design of oxygen biocathodes for biofuel cells. [on SciFinder(R)]