Characteristics of ISFET-type [beta]-Glucosidic Glucoside Sensor Using Thermophilic Enzymes [beta]-Glucosidase and Glucokinase

An ion sensitive field-effect transistor (ISFET) combined with immobilized thermophilic enzymes was applied to the determination of β-D-glucosidic glycosides. In order to improve the stability of the biosensor, the pH-sensing gate of ISFET was covered with the thermostable enzyme layer using thermophilic β-D-glucosidase and glucokinase. The characteristics of the developed bienzyme ISFET sensor were studied using the samples of β-glucosidic glycosides such as salicin and esculin. The dynamic range from 0.3 mM to 30 mM (1 M=1 mol dm-3) was obtained for salicin at pH 7.0. The responses were enhanced in the temperature range from 40 to °C.