A reagentless amperometric biosensor based on the coimmobilization of horseradish peroxidase and methylene green in a modified zeolite matrix

A new biosensor for the amperometric detection of hydrogen peroxide was dev eloped based on the coimmobilization of horseradish peroxidase (POD) and me thylene green on a zeolite modified glassy carbon electrode without the com monly used bovine serum albumin - glutaraldehyde. The large specific surfac e area of such a zeolite matrix resulted in high enzyme and mediator loadin g. The intermolecular interaction between the enzyme and the zeolite was in vestigated using FT-IR Cyclic voltammetry and amperometric measurement demo nstrated that methylene green coimmobilized with POD in this way displayed good stability and could efficiently shuttle electrons between immobilized enzyme and the electrode. Due to the hydrophilic character of the zeolite t he soluble enzyme and methylene green can be retained in the zeolite film, greatly improving the stability of the sensor. Electrocatalytic reduction o f H2O2 at the electrode was evaluated with respect to solution pH, temperat ure and operating potential. The sensor exhibited high sensitivity and coul d be used for more than two months. (C) 1999 Elsevier Science B.V. All righ ts reserved.