Development of a (PQQ)-GDH-anode based on MWCNT-modified gold and its application in a glucose/O2-biofuel cell

In this study a biofuel cell anode is developed on the basis of multi-walled carbon nanotubes (MWCNTs). Recombinant pyrroloquinoline quinone (PQQ) dependent glucose dehydrogenase (GDH) is covalently coupled to a PQQ-layer which is adsorbed onto thiol-modified MWCNTs at a gold electrode. In the presence of glucose a catalytic current starts at a potential of -80 mV vs. Ag/AgCl, 1M KCl. Under substrate saturation current densities of 170-200 μA/cm2 can be achieved. The operation is based on mediated electron transfer of the enzyme. This (PQQ)-GDH-MWCNT-electrode is combined with a MWCNT-modified electrode to which bilirubin oxidase (BOD) is covalently coupled. The resulting membrane-free biofuel cell has an open cell potential of 600 mV and can achieve a power density in the range of 23 μW/cm2.