SENSORS BASED ON FIELD-EFFECT TRANSISTORS

Three models of biosensors based on field-effect transistors are prese nted: a microbial biosensor for glucose determination, a sensor for th e detection of the human immunoglobulin G, and a chemical sensor for t he determination of ammonium ion concentration. A method for immobiliz ation of microbe cells on the surface of field-effect transistors is d eveloped. The possibilities of horseradish peroxidase as a marker enzy me were studied. A chemical sensor design based on a chemically sensit ive membrane generating photoelectromotive force was studied. A high s ensitivity of sensors was shown for the determination of glucose (10(- 4)-10(-3) M) and immunoglobulin G (10-(10)-10(-8) M) in model solution s. The glucose sensor showed high selectivity and stability. It was sh own that sensors based on a polymeric matrix containing a spirobenzopy rane analog and modified by a Nonactin ionophore (ammonium ion sensiti vity from 10(-5) to 10(-3) M) are promising for developing cell and en zymatic biosensors and for detecting a wide range of biologically acti ve compounds.