Towards a high potential biocathode based on direct bioelectrochemistry between horseradish peroxidase and hierarchically structured carbon nanotubes.

Adsorption of horseradish peroxidase (HRP) on graphite rod electrodes sequentially modified with carbon microfibers (CMF) carrying carbon nanotubes in a hierarchically structured arrangement and finally pyrene hexanoic acid (PHA) for improving hydrophilicity of the electrode surface is the basis for the direct bioelectrocatalytic reduction of H(2)O(2) at potentials as high as about +600 mV. The high-potential direct bioelectrocatalytic reduction of H(2)O(2) is implying a direct bioelectrochemical communication between the Fe(IV)=O,P(+*) redox state known as compound I. The HRP loading was optimized leading to a current of 800 microA at a potential of 300 mV.