REAGENTLESS AMPEROMETRIC BIOSENSOR HIGHLY SENSITIVE TO HYDROGEN-PEROXIDE BASED ON THE INCORPORATION OF MELDOLA-BLUE, FUMED SILICA AND HORSERADISH-PEROXIDASE INTO CARBON-PASTE

A reagentless amperometric sensor highly sensitive to H2O2 has been pr epared by incorporating fumed silica, horseradish peroxidase (HRP) and Meldola Blue into carbon paste. The efficient mediating ability to sh ift electrons between HRP and the carbon paste electrode via Meldola B lue was investigated by cyclic voltammetric and amperometric measureme nts. Reproducibility, response time, detection limit, selectivity and effects of applied potential, temperature and pH on the response of th e sensor are reported. The high sensitivity of the sensor with a detec tion limit of 0.1 mu mol/l arose from the high efficiency of the bioel ectrocatalytic reduction of hydrogen peroxide via HRP and Meldola Blue . The dependence of the Michaelis-Menten constant on the applied poten tial and the mediator concentration has been investigated and the resu lts are presented.