Immobilization of Two Enzyme System of Glucoamylase and Glucoseoxidase onto Platinum Electrode and its Characteristics as Maltose Sensor

Amino groups were attached to a platinized platinum electrode through alkylamine-silanization. Glucoamylase (GA) and glucoseoxidase (GOD) were then immobilized directly onto the platinum electrode. The immobilized two enzyme electrode (GA-GOD-Pt) was coupled with a Ag/AgCl electrode as its counter electrode and its characteristics as a maltose sensor were investigated. An increased linearity was observed as the pH value of the ambient solution increased. Its tendency of increased linearity with increased pH value toward 7.5 was examined through the aid of theoretical analysis of the relation between electrode current and maltose concentration and the use of the GA-GOD-Pt electrode under conditions of somewhat depressed GA activity was recommended. The dynamic response of the GA-GOD-Pt to the stepwise change of maltose concentration was found to be expressed by a first order response model without time delay.