Aluminum phthalocyanine-streptavidin: new, sensitive fluorescent tracer for immunoassay.
A new fluorescent reagent based on aluminum phthalocyanine has been developed for general application to immunoassay. This highly sensitive fluorophore, Ultralite 680, may be covalently attached to a variety of biological entities for use as a tracer. We report the use of an Ultralite 680-streptavidin-digoxin conjugate as a tracer in a direct, competitive, heterogeneous, fluorescent immunoassay of digoxin. The assay is performed manually with 50 microL of serum and no sample pre-treatment. Primary anti-digoxin antibody is incubated with a serum sample containing digoxin and Ultralite 680-streptavidin-digoxin. Bound and free tracer are separated, and the bound fluorescence is released and quantified with a commercially available spectrofluorometer. Assay precision was good (CV = 7.05% at a digoxin concentration of 2.00 micrograms/L) and results by our method correlated well with those by a conventional RIA (r = 0.9650, n = 24).
Kelly
T A
TA
Ultra Diagnostics Corp., Seattle, WA 98105.
Hunter
C A
CA
Schindele
D C
DC
Pepich
B V
BV
D000535:Aluminum; D000911:Antibodies, Monoclonal; D001426:Bacterial Proteins; D004077:Digoxin / Q000097:blood*; D005455:Fluorescent Antibody Technique; D005456:Fluorescent Dyes; D006801:Humans; D007211:Indoles; D009942:Organometallic Compounds
D000911:Antibodies, Monoclonal; D001426:Bacterial Proteins; D005456:Fluorescent Dyes; D007211:Indoles; D009942:Organometallic Compounds; C070041:aluminum phthalocyanine-streptavidin complex; D004077:Digoxin; D000535:Aluminum