FIBER OPTIC IMMUNODETECTORS: SENSORS OR DOSIMETERS? .
Biosensors based on specific interaction of the analyte of interest (ligand) with a biochemical agent (receptor) which specifically and tightly binds the analyte are being developed by many groups, agencies, and institutions using a variety of detection technologies. We are studying fluorescent methods using evanescent wave excitation on the surface of planar and cylindrical (fiber optic) optical waveguides. A relatively low ligand-receptor binding constant results in reversibility but low sensitivity. Most biological receptors bind very strongly and specifically - almost irreversibly - which provides an 'irreversible' means of detection. Means to regulate ligand-receptor binding constants are discussed in order to provide semi-reversible, sensitive, specific sensors, rather than 'one-shot' detectors or dosimeters.