A simple and portable fiberoptic instrument for fluorimetric bioassays is described. The instrument is designed to be readily adaptable to commercially available biotesting wells on microplates. The microwells can also be used as interchangeable sensor heads. The utility of the fiberoptic biosensor is illustrated with a model enzyme-linked immunosorbent assay (ELISA) used to measure varying amounts of rabbit immunoglobulin G from 10 pg to 1 μg. The detection method utilizes an enzyme-amplified immunoassay of 4-methylumbelliferone phosphate as the enzyme substrate. The sensitivity of this assay is three orders of magnitude better than that obtained with a conventional ELISA absorption spectrometric assay using a commercially available reader.
T. Vo-Dinh, G. D. Griffin, and K. R. Ambrose, "A Portable Fiberoptic Monitor for Fluorimetric Bioassays," Appl. Spectrosc. 40, 696-700 (1986)