Europium and terbium chelators for time-resolved fluorometric assays

Abstract

Fluorogenic chelators for Eu.sup.3+ and Tb.sup.3+ are provided, they form highly fluorescent complexes with Eu.sup.3+ and Tb.sup.3+. In all cases, the fluorescence observed was lanthanide-specific, long-lived and it was monitored by microsecond time-resolved fluorometry. The fluorogenic chelators could be quantified, in the presence of excess lanthanide, at levels <10.sup.-8 mol/L. Two new fluorogenic chelators can form ternary complexes with Eu.sup.3+ and Tb.sup.3+, in the presence of EDTA. The structures of the identified chelators is such that enzyme substrates can be used for enzyme-labelled time-resolved fluorometric immunoassays. The chelator 4-methylumbelliferyl phosphate which forms fluorescent, long-lived complexes with Eu.sup.3+, can be split by alkaline phosphatase to phosphate and 4-methylumbelli-ferone which does not form fluorescent complexes with Eu.sup.3+. Highly sensitive immunoassays for thyrotropin and thyroxine in human serum are demonstrated.

Dependencies are inferred from the claim text.