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Proceedings Paper

Homogeneous model immunoassay of thyroxine by phase-modulation fluorescense spectroscopy
Author(s): Alvydas J. Ozinskas; Henryk M. Malak; Judy Britz; Richard B. Thompson; Peter A. Koen; Joseph R. Lakowicz
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Paper Abstract

We describe a homogeneous competitive model immunoassay for determination of thyroxine by multi-frequency phase-modulation fluorescence. Using a non-radiative energy transfer transduction mechanism, B-phycoerythrin conjugated to thyroxine is the energy donor and a carboxymethylindocyanine dye conjugated to anti-thyroxine antibody is the energy acceptor. Energy transfer from B-phycoerythrin to the acceptor results in a decreased lifetime and/or phase angle. The fluorescence lifetime change reflects the extent of energy transfer. In the competitive immunoassay format, the donor-thyroxine conjugate and an analytical sample of thyroxine compete for acceptor-antibody binding sites, resulting in a phase angle change which is dependent on the amount of thyroxine in the sample. Dose response curves of phase angle versus thyroxine concentration demonstrate a broader dynamic range than comparable steady state intensity curves. Since phase-modulation lifetime measurements are largely independent of total signal intensity, sources of optical interference are minimized. The potential for whole blood measurements exists since the energy transfer lifetime method can be extended to longer wavelengths.

Paper Details

Date Published: 18 May 1993
PDF: 9 pages
Proc. SPIE 1885, Advances in Fluorescence Sensing Technology, (18 May 1993); doi: 10.1117/12.144697
Show Author Affiliations
Alvydas J. Ozinskas, Becton Dickinson Advanced Diagnostics (United States)
Henryk M. Malak, Univ. of Maryland School of Medicine (United States)
Judy Britz, Becton Dickinson Advanced Diagnostics (United States)
Richard B. Thompson, Univ. of Maryland School of Medicine (United States)
Peter A. Koen, Becton Dickinson Vacutainer Systems (United States)
Joseph R. Lakowicz, Univ. of Maryland School of Medicine (United States)


Published in SPIE Proceedings Vol. 1885:
Advances in Fluorescence Sensing Technology
Joseph R. Lakowicz; Richard B. Thompson, Editor(s)

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