Direct electron transfer of PQQ-glucose dehydrogenase at modified carbon nanotubes electrodes

In order to establish efficient enzyme-electrode-contacts for the pyrroloquinoline quinone dependent glucose dehydrogenase (PQQ-GDH) different immobilisation strategies are investigated. Multi-walled carbon nanotubes (MWCNT) on gold electrodes are modified by chemical treatment and by (poly)-aniline derivatives. The electropolymerisation of methoxy-m-anilinesulfonic acid and m-aminobenzoic acid on the MWCNTs allows the covalent coupling of the PQQ-GDH. Such a poly-[ASA-ABA]/MWCNT/Au electrode can achieve current densities of up to 500 μA/cm² at a potential of 100 mV vs. Ag/AgCl. Furthermore investigations with small amounts of free PQQ indicate direct electron transfer between enzyme and electrode.