Development of alcohol dehydrogenase–polypyrrole electrodes by adsorption and crosslinking for ethanol oxidation

Enzymatic-polymeric electrodes are prepared by immobilizing the enzyme alcohol dehydrogenase from Saccharomyces cerevisiae in polypyrrole, potentiostatically electrodeposited onto carbon paper. The applied enzymatic immobilization procedures are direct adsorption and crosslinking with glutaraldehyde. Electrodes are characterized by cyclic voltammetry, showing that ethanol oxidation occurs at around 0 V (versus calomel) for the enzymatic electrodes. Recorded current values due to ethanol oxidation in enzymatic polymeric electrodes are higher by two orders of magnitude, than those recorded for ethanol oxidation in carbon enzyme electrodes. The polymeric enzymatic electrodes crosslinked with glutaraldehyde show higher current values than those with adsorbed enzyme, reflecting a better retention of the protein in the electrode, and preserve catalytic activity for longer times. Spectrophotometric measurements are performed in order to determinate enzymatic activity. Fuel cell test show better performance for the crosslinked enzymatic electrode.