A PHENAZINE METHOSULFATE-MEDIATED SENSOR SENSITIVE TO LACTATE BASED ON ENTRAPMENT OF LACTATE OXIDASE AND HORSERADISH-PEROXIDASE IN COMPOSITE MEMBRANE OF POLY(VINYL ALCOHOL) AND REGENERATED SILK FIBROIN

An amperometric phenazine methosulphate-mediated sensor sensitive to l actate was fabricated, which was based on immobilization of lactate ox idase and horseradish peroxidase in a novel composite membrane of poly (vinyl alcohol) and regenerated silk fibroin. The water absorbability and mechanical properties of the composite membrane were investigated. Horseradish peroxidase (HRP) was employed in the catalytic reduction of hydrogen peroxide, formed by the lactate oxidase reaction, to ampli fy the amperometric response of the lactate sensor. In this bienzyme c onfiguration, phenazine methosulphate was used as an electron transfer mediator between immobilized HRP and a glassy carbon electrode. Effec ts of pH, temperature, applied potential and concentration of phenazin e methosulphate on the steady-state bioelectrocatalytic oxidation of l actate at the sensor were evaluated. Dependence of Michaelis-Menten co nstant K-m(app) on the concentration of phenazine methosulphate and ap plied potential was also investigated. The response of the sensor to l actate reached 95% steady-state current within 20 s. Copyright (C) 199 6 Elsevier Science Ltd