Steroids fluorescence immunoassay

B2. Barnard, G., and Kohen, E., Monitoring ovarian function by the simultaneous time-resolved fluorescence immunoassay of two urinary steroid metabolites. Clin. Chem. 44,1520-1528 (1998). 

In this assay, marker-labeled antigen itself acts as substrate. Kohen et al. (K9) developed a homogeneous immunoassay for steroid using a steroid-fluorescent dye conjugate that yields fluorescent products upon hydrolysis with enzyme. The steroid-fluorescent dye conjugate is inactive as a substrate when bound to the antibody to steroid [F-Ag Ab]. But when unlabeled steroid [Ag] is added, it binds competitively to the antibody [Ab Ag],. and the free form of steroid-fluorescent dye conjugate [F-Ag], which is... 

Antibody-Enhanced Hydrolysis of Steroid-Fluorescent Dye Conjugate Immunoassay... 

Depending on the manner of labeling, various kinds of immunoassays are used in the analysis of steroid hormones RIA, enzyme immunoassay, fluorescence immunoassay, fluorescence polarization immunoassay, and luminescence immunoassay. 

K6. Kobayashi, Y., Miyai, K., Tsubota, N., and Watanabe, F., Direct fluorescence polarization immunoassay of serum cortisol. Steroid 34, 829-834 (1979). 

Tsuji A, Maeda M, Arakawa H, Shimizu S, Ikegami T, Sudo Y, et al. Fluorescence and chemiluminescence enzyme immunoassays of 17a-hydroxyprogesterone in dried blood spotted on filter paper. J Steroid Biochem 1987 28 33-40. 

A fluorescence-quenching immunoassay for cortisol, based upon the use of a tracer comprising fluorescein linked to the steroid via a 21-amino-group, claims a good correlation with radioimmunoassay results. Separation of free and bound fractions is unnecessary with this system.141... 

Fluorescein-labelled oestradiol has been used as a probe for anti-oestradiol antibody. The probe material was prepared by condensing the 6-carboxy-methyloximino-derivative of oestradiol with fluorescein amine . It had a fluorescence emission spectrum similar to that of fluorescein, and permitted a sensitive immunoassay of oestradiol. A system suitable for spin-immunoassay of steroids, using nitroxides for spin-labelling, is described on p. 264. 

The interaction of artificial metal ions/complexes with peptides/proteins [11], nucleic acids/DNA [12,13], enzymes [14], steroids [15] and carbohydrates [16] forms a bridge between natural and artificial macromolecular metal complexes. Biometal-organie chemistry concentrates on such complexes [17]. The reason for the increasing interest in this field lies in medical applications of metal complexes (cancer, photodynamic therapy of cancer, immunoassays, fluorescence markers, enantioselective catalysis, template orientated synthesis of peptides, etc.). Figure 2-4 presents an overview of metals in medicine [18]. Some examples are given below. 

Other variants of immunoassay methods used in the analysis of steroid hormones are the fluorescence polarization immunoassay, where the label is fluorescein, coupled to the steroid, and luminescence immunoassay, where the steroid is bound to amino-alkylethylluminol. The basis of the luminescence assay is the luminescence generated by the action of hydrogen peroxide/peroxidase, which is measured by a luminometer (LIA, CELIA). 

The Allen-Doisy test was a biological test for E., in which the response of ovarectomized mice to urinary or plasma E. was observed. It was replaced in clinical practice by a colorimetrie test, the Korber method, in which the E. are treated with HjSOj and hydroqui-none to produce intensely fluorescing derivatives. However, the development of Immunoassays (see) for the steroid hormones has made the Korber method obsolete for routine clinical assays. 

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