Thyroxine fluorescence immunoassay

Figure 14.16. Dose-response curves for a phase fluorescence immunoassay of thyroxine at modulation frequencies of 49.5 MHz ( ), 64.8 MHz (a), and 99.1 MHz (o). (From Ref. 34 with permission.)...

M5. Miyai, K., Endo, Y., and Hata, N., Fluorescence immunoassay of thyroxine with clonotype antibody fractionated by ehromatofoeusing. Proc. Int. Fed. Clin. Chem., 12th, in press (1985). 

A. J. Ozinskas, H. Malak, J. Joshi, H. Szmacinski, J. Britz, R. B. Thompson, P. A. Koen, and J. R. Lakowicz, Homogeneous model immunoassay of thyroxine by phase-modulation fluorescence spectroscopy, Anal. Biochem. 213, 264-270(1993). 

Homogeneous TR-FIAs have been reported in which proprietary lanthanide chelates are used. In a homogeneous immunoassay for T4, a fluorescent europium chelate coupled to thyroxine is quenched by antibody binding. 90 A similar approach is used for estrone-3-glucuronide. 91 TRFIAs based on homogeneous methods have not yet become widely used. 

Fig. 6. Comparison of immunoassays using clonotype antibodies. The EDso values (thyroxine concentration corresponding to 50% of bound form at zero concentration of thyroxine) in thyroxine immunoassays using clonotype antithyroxine antibody prepared by fast protein liquid chromatography (FPLC). RIA, double-antibody radioimmunoassay FLA, fluorescence polarization immunoassay EIA, enzyme immunoassay. [Cited from Miyai et al. (M5).]...

Symons RG, Vining RF. An evaluation of a fluorescence polarization immunoassay of thyroxin and thyroxin-uptake. CLin Chem 1985 31 1342-8. 

H Arakawa, M Maeda, A Tsuji. Chemiluminescence enzyme immunoassay for thyroxin with the use of glucose oxidase and a bis(2,4,6-trichlorophenyl) oxalate-fluorescent dye system. Clin Chem 31 430, 1985. 

A fifth group of procedures includes the use of an array format. The usual 96-well plate for immunoassay measures the fluorescence in liquid phase either by determining the unbound fraction or by dissolving the bound reporter molecules to overcome problems related to autofluorescence, scattering, and back-reflection, although the selection of an appropriate solid support allows for the measurement of the fluorescence directly on the solid surface. For example, a heterogeneous fluoroimmunoassay using fluorescein-labeled antibodies for total thyroxin in serum uses this procedure. 

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