Fiberoptic immunosensors with continuous analyte response

Fiberoptic fluorescence signal transmission has several advantages for immunosensor design: physical flexibility for remote sensing, no risk of electrical interference, high signal-to-noise ratio with little attenuation over distance, and the capacity to both measure several analytes with fluorescence from a single fiber and bundle fibers without significant crosstalk. For many immunosensors these possibilities have offered little advantage because they have been designed for single use, or they have required regeneration that usually can not be accomplished in situ. The sensor described here, developed by Anderson and Miller (1 ), is self-contained and completely reversible because the antibody has a sufficiently fast effective dissociation rate constant (k _dis ). The sensor can be used for hours to days depending on the application. It has been calibrated and used in blood to measure therapeutic concentrations of free phenytoin (PHT) (2 ), and the design can be modified for use with other haptens, such as theophylline (THEO) (3 ). Here we present general instructions for preparation of reversible fiberoptic immunosensors, as well as specific details for construction of sensors to phenytoin and theophylline.