Syntheses and properties of luminescent lanthanide chelate labels and labeled haptenic antigens for homogeneous immunoassays.

Lanthanide chelate labels containing substituted 4-(arylethynyl)pyridine as the chromogenic moiety and iminobis(acetic acid) groups as the chelating part were synthesized. N-Succinimidyl esters of the carboxy derivatives of thyroxine and progesterone were prepared and coupled to the aliphatic amino groups of the synthesized lanthanide chelates. The luminescence properties of the chelates and labeled haptenic antigens were measured in ethanol and in an aqueous buffer containing either albumin or detergents as luminescence-modulating compounds. The energy transfer enhanced ion luminescence of the derivatives containing a para-amino-substituted phenyl ring showed particularly strong dependence on environmental changes, which makes these derivatives well suited for homogeneous time-resolved fluoroimmunoassay based on the use of external luminescence modulators.