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Proceedings Paper

Fiber Optic-Based Immunosensors: A Progress Report
Author(s): Suresh K. Bhatia; Richard B. Thompson; Lisa C. Shriver-Lake; Michael Levine; Frances S. Ligler
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Paper Abstract

Immobilization of functional antibodies on optical fibers at high density and configuration of optical components so as to maximize the signal/noise (S/N) are key elements in the development of fiber optic-based immunosensors. Functional antibodies were immobilized on silica substrates using thiol-terminal silanes and heterobifunctional crosslinkers. Anti-IgG antibody was routinely immobilized on glass cover slips at 0.66 ng/mm2 and on silica fibers at 0.96 ng/mm2 using this procedure. The immobilized antibody bound 0.37-to-0.55 moles IgG antigen per mole antibody. In addition, the amount of protein nonspecifically adsorbed to the antibody-coated surface was only 2-6% of the total antigen binding. Initial assessments of antibody immobilization and function were performed using radiolabelled proteins. In order to convert the system to fluorescence, antigens were labelled with a variety of fluorophores and optical components were tested in a variety of configurations. Problems with background fluorescence were identified stemming from fluorescence of the glass substrates, stickiness of fluorescent proteins, and fluorescence from optical components. The latter problem was addressed by testing a variety of components and configurations in a sensor testbed to determine which provided the greatest sensitivity. Using this iterative approach, we were able to identify factors which degrade sensitivity and to detect 100 pM fluorophor in a distal cuvette configuration with S/N of 14.

Paper Details

Date Published: 17 May 1989
PDF: 7 pages
Proc. SPIE 1054, Fluorescence Detection III, (17 May 1989); doi: 10.1117/12.951556
Show Author Affiliations
Suresh K. Bhatia, Geo-Centers, Inc. (United States)
Richard B. Thompson, Naval Research Laboratory (United States)
Lisa C. Shriver-Lake, Naval Research Laboratory (United States)
Michael Levine, Naval Research Laboratory (United States)
Frances S. Ligler, Naval Research Laboratory (United States)

Published in SPIE Proceedings Vol. 1054:
Fluorescence Detection III
E. Roland Menzel, Editor(s)

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