Organic interlayers for oxygen reducing electrodes based on bilirubin oxidase and MWCNT modified gold

Electrochemical properties of bilirubin oxidase (BOD) and multi-walled carbon nanotubes (MWCNT) modified gold electrodes were characterised by linear sweep voltammetry. For enhancement of the direct electron transfer of BOD an interlayer of different aromatic compounds was introduced between the adsorbed or covalently bound enzyme and the MWCNTs. By usage of pyrroloquinoline quinone (PQQ) an increased catalytic oxygen current was observed. The reduction process starts at a potential of +500 mV vs. Ag/AgCl, 1 M KCl. The peak current density in unstirred solution could be determined with about 500 μA/cm2. A reduction of the diffusion layer thickness by stirring enhances the current density up to 1600 μA/cm2 (at +250 mV).