Hydrogen peroxide biosensor based on a polyion complex membrane containing peroxidase and toluidine blue, and its application to the fabrication of a glucose sensor

A polyion complex membrane containing peroxidase and toluidine blue (PIC-POx-TB) was prepared by mixing polystyrene sulfonate, POx, TB, and poly-l-lysine solutions on the glassy carbon electrode. Current response to hydrogen peroxide on PIC-POx-TB electrode was measured at a potential of −0.25 V vs. Ag/AgCl: the response time was ca. 2 min, and the response current was proportional to the hydrogen peroxide concentration up to 50 μM. The lower detection limit was 1 μM (signal-to-noise ratio, S/N = 3). Current ratio between l-ascorbate and hydrogen peroxide at the same concentration was determined to be several percent. The PIC-POx-TB electrode was used as a hydrogen peroxide sensor. On the PIC-POx-TB electrode, glucose oxidase (GOx) was attached by the glutaraldehyde method. The GOx-PIC-POx-TB electrode was used for glucose detection. Response to glucose was proportional to the glucose concentration up to 100 μM, and lower detection limit was 5 μM (S/N = 3). The response current was not affected by l-ascorbate.