Laccase–gold nanoparticle assisted bioelectrocatalytic reduction of oxygen

It was found that homogeneous activity of Trametes hirsuta laccase is considerably diminished in the presence of gold nanoparticles (Au-NPs). Heterogeneous electron transfer studies revealed that Au-NPs facilitate direct electron transfer (DET) between the T1 copper site of the laccase and the surface of Au-NP modified electrodes. DET was characterized by the standard heterogeneous ET constant of 0.5 ± 0.6 s−1 at Au-NPs with an average diameter of 50 nm. As a consequence of this a well pronounced DET based bioelectrocatalytic oxygen reduction with current densities of 5–30 µA cm−2 has been achieved at the laccase–Au-NP modified electrodes.