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 transist ors were prepared by cross-linking a mixture of glucose oxidase and bo vine 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-coat ing of 0.5% polymer solution in ethanol. The use of this additional me mbrane resulted in substantial extension of the dynamic range of the s ensor (up to 20 mM of glucose) and reduction of buffer concentration d ependence of the sensor response. Also the effects of pH and ionic str ength were examined for the sensors with and without additional membra nes.