Simplifying Enzymatic Biofuel Cells: Immobilized Naphthoquinone as a Biocathodic Orientational Moiety and Bioanodic Electron Mediator

An elegant method to perform bioelectocatalysis with different oxidoreductases at the cathode and at the anode of an enzymatic biofuel cell is presented. Noncovalent functionalization of multiwalled carbon nanotubes (MWCNTs) was accomplished via pi-pi interactions of pyrene derivatives. 1-[Bis(2-naphthoquinonyl)aminomethyl]pyrene was synthesized and successfully immobilized on MWCNTs. The incorporation of the quinone-modified MWCNTs within enzymatic bioelectrocatalytic applications was evaluated. The hydrophobic nature of the naphthoquinone aided orientation of laccase and bilirubin oxidase toward the electrode, which enhanced their ability to undergo the direct bioelectrocatalysis of oxygen. In contrast, the electrochemical properties of the quinone were used at the bioanode to mediate electrons from the bioelectrocatalytic oxidation of glucose by pyrroloquinoline quinone-dependent glucose dehydrogenase. This method demonstrates how the smart modification of MWCNTs can develop materials, which can be used simultaneously at both electrodes of enzymatic biofuel cells.