A pyrroloquinolinequinone-dependent glucose dehydrogenase (PQQ-GDH)-electrode with direct electron transfer based on polyaniline modified carbon nanotubes for biofuel cell application

Abstract

In this study we present a pyrroloquinolinequinone-dependent glucose dehydrogenase [(PQQ)-GDH] electrode with direct electron transfer between the enzyme and electrode. Soluble pyrroloquinolinequinone-dependent glucose dehydrogenase from Acinetobacter calcoaceticus is covalently bound to an electropolymerized polyaniline copolymer film on a multi-walled carbon nanotube (MWCNT)-modified gold electrode. The pulsed electropolymerization of 2-methoxyaniline-5-sulfonic acid (MASA) and m-aminobenzoic acid (ABA) is optimized with respect to the efficiency of the bioelectrocatalytic conversion of glucose. The glucose oxidation starts at −0.1V vs. Ag/AgCl and current densities up to 500μA/cm2 at low potential of +0.1V vs. Ag/AgCl can be achieved. The electrode shows a glucose sensitivity in the range from 0.1mM to 5mM at a potential of +0.1V vs. Ag/Ag/Cl. The dynamic range is extended to 100mM at +0.4V vs. Ag/AgCl. The electron transfer mechanism is studied and buffer effects are investigated.The developed enzyme electrode is examined for bioenergetic application by assembling of a membrane-less biofuel cell. For the cathode a bilirubin oxidase (BOD) based MWCNT-modified gold electrode with direct electron transfer (DET) is used. The biofuel cell exhibits a cell potential of 680±20mV and a maximum power density of up to 65μW/cm2 at 350mV vs. Ag/AgCl.