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Proceedings Paper

Fiber Optic Chemical Sensors Using Immobilized Bioreceptors
Author(s): David R. Walt; Shufang Luo; Christiane Munkholm
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Paper Abstract

Optrodes employing immobilized enzymes were developed using covalent attachment of sensor reagents. This development is an extension of the original application of this sensor technology in which a pH sensor was constructed with the pH sensitive dye fluorescein incorporated into a polymer covalently attached to the fiber tip. This sensor displayed significantly improved response times over previous fiber optic sensors because of reduced diffusion limitations. In addition, the signal intensities were greatly enhanced by the high concentration of fluorescent dye localized at the fiber tip. With the anticipation that these qualities would be preserved, a class of sensors based on the immobilization of biomolecules in the polymer matrix became the next goal. This paper will first describe a fiber optic probe prepared by immobilizing esterase in a crosslinked polyacrylamide matrix. The immobilized esterase converts the nonfluorescent fluoresceindiacetate into fluorescein. Both the steady state level and kinetic generation of fluorescence can be related to the concentration of fluoresceindiacetate. A fiber optic sensor for penicillin has been made by coimmobili zing penicillinase with a pH sensitive fluorescent dye. Penicillinase converts penicillin to penicilloic acid which produces a microenvironmental pH change in the dye-containing polymer matrix resulting in a concommitant change in fluorescence. The change in fluorescence is proportional to the concentration of penicillin and a 95% response is reached in 40-60 seconds. The sensor has a detection limit of 2.5 x 10-4 M. Another class of sensors using immobilized bioreceptors will be based on the principles of fluoroimmunoassay. This paper will discuss some basic principles and problems of 1) fluorescence quenching immunoassays, 2) fluorescence excitation transfer immunoassays, and 3) energy transfer immunoassays for digoxin. Both advantages and inherent problems for these sensor preparations will be addressed.

Paper Details

Date Published: 21 June 1988
PDF: 5 pages
Proc. SPIE 0906, Optical Fibers in Medicine III, (21 June 1988); doi: 10.1117/12.945256
Show Author Affiliations
David R. Walt, Tufts University (United States)
Shufang Luo, Tufts University (United States)
Christiane Munkholm, Tufts University (United States)

Published in SPIE Proceedings Vol. 0906:
Optical Fibers in Medicine III
Abraham Katzir, Editor(s)

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