A BIOSENSOR THAT USES ION-CHANNEL SWITCHES

Biosensors are molecular sensors that combine a biological recognition mechanism with a physical transduction technique. They provide a new class of inexpensive, portable instrument that permit sophisticated an alytical measurements to be undertaken rapidly at decentralized locati ons(1). However, the adoption of biosensors for practical applications other than the measurement of blood glucose is currently limited by t he expense, insensitivity and inflexibility of the available transduct ion methods. Here we describe the development of a biosensing techniqu e in which the conductance of a population of molecular ion channels i s switched by the recognition event. The approach mimics biological se nsory functions(2,3) and can be used with most types of receptor, incl uding antibodies and nucleotides. The technique is very flexible and e ven in its simplest form it is sensitive to picomolar concentrations o f proteins. The sensor is essentially an impedance element whose dimen sions can readily be reduced to become an integral component of a micr oelectronic circuit. It may be used in a wide range of applications an d in complex media, including blood. These uses might include cell typ ing, the detection of large proteins, viruses, antibodies, DNA, electr olytes, drugs, pesticides and other low-molecular-weight compounds.