(393c) Enzyme Immobilization and Stabilization Into Polyaniline Nanofibers for Biofuel Cells
A model enzyme, glucose oxidase (GOx), was immobilized and stabilized into polyaniline nanofibers (PANFs) via a three-step process, consisting of enzyme adsorption, precipitation, and crosslinking (EAPC). EAPC of GOx showed 9.6 and 4.2 times higher enzyme activities per unit weight of PANFs than those of enzyme adsorption (EA) and enzyme adsorption/crosslinking (EAC), respectively. Under rigorous shaking at room temperature for 56 days, the relative activities of EA, EAC and EAPC, defined as the percentage of residual activity to the initial activity, were 22%, 19% and 91%, respectively. The potential application of EAPC-GOx in enzyme-based biofuel cells was checked by preparing the enzyme anode via Nafion-entrapment of EAPC-GOx/PANFs onto the carbon paper. The two critical problems of biofuel cells, low power densities and short lifetime, could be solved in part by using highly-loaded and stable EAPC-GOx. The maximum power density could be maintained without any loss even after incubation for 2 months or thermal treatment at 60°C for 4 hours, suggesting the good performance stability of the EAPC anode. It is anticipated that highly-stable EAPCs/PANFs will be employed in various other enzyme applications such as bioconversion and bioremediation as well as electrochemical biocatalysis.