Development of a new amperometric biosensor based on polyphenoloxidase and polyethersulphone membrane*

An amperometric biosensor based on the enzyme polyphenoloxidase (PPO), which makes the bioelectrocatalysis of phenolic compounds, was developed and optimized using cathecol as substrate. Polyethersulphone membranes were used for enzyme immobilization. Polyphenoloxidase oxidizes monophenols (cresolase activity) and diphenols (catecholase activity) into the corresponding o-quinones; the o-quinones formed in the enzymatic catalysis are then reduced back to cathecol at –200 mV (vs. Ag, AgCl) at a platinum electrode. The polyphenoloxidase immobilized was from commercial origin or extracted from mushrooms. p-Cresol and phenol substrates were also tested. Reproducibility, response time, linearity, sensitivity, and stability of the biosensor were studied.