Operation stability of chitosan and nafion-chitosan coatings on bioelectrodes in enzymatic glucose biofuel cells.

The performance of bioelectrodes in enzymatic glucose biofuel cell is not only dependent on the enzyme immobilization schemes but it is greatly influenced by the ability of the enzyme to exhibit favorable orientation for a direct electron transfer (DET) between the enzyme and the current collector. The electrochemical investigation of chitosan and nafion-chitosan coatings on multi-walled carbon nanotubes (MWCNTs) immobilized with pyrroloquinoline quinone dependent glucose dehydrogenase (PQQ-GDH) and bilirubin oxidase (BOD) at the bioanode and biocathode, respectively revealed interesting operational stability performance for the enzymatic biofuel cells. The bioelectrodes operated in DET mode and the chitosan coated biofuel cell system overall demonstrated higher power (156 μW) output. The stability of PQQ-GDH bioanodes varied based on the enzyme concentrations, wherein a concentration of 2.5 mg/ml resulted in a significant enhancement in stability and the maximum power density of 1.6 mW/cm2 compared to enzyme concentrations of 5 mg/ml PQQ-GDH or higher.