Glucose-sensitive ion-sensitive field-effect transistor-based biosensor with additional positively charged membrane. Dynamic range extension and reduction of buffer concentration influence on the sensor response

Glucose-sensitive sensors based on ion-sensitive field-effect transistors were prepared by cross-linking a mixture of glucose oxidase and bovine serum albumin in saturated glutaraldehyde vapour on the sensitive area of the transducer. After this procedure, 4-vinylpyridine-styrene copolymer membranes were deposited on top of the sensors by drop-coating of 0.5% polymer solution in ethanol. The use of this additional membrane resulted in substantial extension of the dynamic range of the sensor (up to 20 mM of glucose) and reduction of buffer concentration dependence of the sensor response. Also the effects of pH and ionic strength were examined for the sensors with and without additional membranes.