Bioelectrocatalysis by Microperoxidase‐11 in a Multilayer Architecture of Chitosan Embedded Gold Nanoparticles

Abstract

Abstract We report on the redox behaviour of the microperoxidase‐11 (MP‐11) which has been electrostatically immobilized in a matrix of chitosan‐embedded gold nanoparticles on the surface of a glassy carbon electrode. MP‐11 contains a covalently bound heme c as the redox active group that exchanges electrons with the electrode via the gold nanoparticles. Electroactive surface concentration of MP‐11 at high scan rate is between 350±50 pmol cm −2 , which reflects a multilayer process. The formal potential ( E °′) of MP‐11 in the gold nanoparticles‐chitosan film was estimated to be −(267.7±2.9) mV at pH 7.0. The heterogeneous electron transfer rate constant ( k s ) starts at 1.21 s −1 and levels off at 6.45 s −1 in the scan rate range from 0.1 to 2.0 V s −1 . Oxidation and reduction of MP‐11 by hydrogen peroxide and superoxide, respectively have been coupled to the direct electron transfer of MP‐11.