STREPTAVIDIN-BASED MACROMOLECULAR COMPLEX LABELED WITH A EUROPIUM CHELATOR SUITABLE FOR TIME-RESOLVED FLUORESCENCE IMMUNOASSAY APPLICATIONS

We found that when we Incubate SA-TG-(BCPDA)150 (a conjugate of streptavidin (SA) with thyroglobulin (TG), which is labeled with the europium chelator 4,7-bis(chlorosulfophenyl)-1,10-phenanthroline-2,9-dlcarboxylic acid (BCPDA)), with BCPDA-labeled thyroglobulln [TG-(BCPDA)150], In the presence of a suitable amount of Eu3+, a new macromolecular complex is formed with a molecular weight of about 3 x 106. This macromolecular complex is stable and can be used as a streptavidin-based universal detection system for devising time-resolved fluorescence immunoassays. This new reagent yields an 8–26-fold Improvement in the detection limits of seven different Immunofluorometric assays In comparison to the reagent SA-TG-(BCPDA)150, which we have recently described (Anal. Chem. 1989, 61, 48–53). © 1990, American Chemical Society. All rights reserved.