Fluorescence immunoassays using fluorescent dyes free of aggregation and serum binding

A fluorescent probe comprising a marker component linked to a target analyte or a analog thereof, wherein:

• (a) said marker component comprises a fluorophore moiety comprising a luminescent substantially planar molecular structure coupled to two polyoxyhydrocarbyl moieties, one located on either side of the planar molecular structure;
• (i) wherein said luminescent substantially planar molecular structure comprises a substantially planar macrocylic multidentate ligand which coordinates to a central atom,
• (ii) wherein said central atom coordinates to said polyoxyhydrocarbyl moieties,
• (iii) wherein said multidentate ligand comprises an optionally substituted nitrogen containing macrocycle selected from the group consisting of a porphyrin and an azaporphyrin derivative and
• (b) said planar molecular structure is linked at adjacent sites of the periphery of said structure to a carboxyl group and said target analyte or said analog thereof, wherein said target analyte is selected from the group consisting of an antigen, a hapten, an antibody, a drug selected from the group consisting of a steroid, a hormone, an antiasthmatic, an antineoplastic, an antiarrhythmic, an anticonvulsant, an antiarthritic, an antidepressant, and a cardiac glycoside, a metabolite of the drug, and a peptide and wherein said target analyte comprises a free primary or secondary amino group or a free carboxyl group.