Monomeric phthalocyanine reagents

Abstract

Fluorescent and/or chromogenic reagents in which a phthalocyanine derivative is monomerically conjugated with an antigen, antibody, oligonucleotide, or nucleic acid. Methods are presented in in which greater than 90% of the phthalocyanine dyes are monomeric when conjugated. This greatly enhances their performance as detectable markers in immunoassays, nucleic acid probe assays, immunoblotting, hybridization assays, microscopy, imaging, flow cytometry, DNA sequencing, and photodynamic therapy. For use as fluorophores, the free base phthalocyanine may or may not be metallated. Metals for fluorescent phthalocyanine include aluminum, silicon, phosphorus, gallium, germanium, cadmium, scandium, magnesium, tin, and zinc. For use as chromogens, the phthalocyanine may or may not be metallated. For use in aqueous solution, the phthalocyanine macrocycle should be derivatized with water-solubilizing substituents such as sulfonic acid, phosphate, phosphonate, hydroxy, phenoxy, amino, ammonium, or pyridinium groups. To promote disaggregation, metallation with an atom of +3 valence or higher is recommended, so that the monomer will take on an axial ligand in aqueous solution. For use in enzymatic immunoassays and enzymatically enhanced nucleic acid probe assays, the monomeric phthalocyanine derivative is conjugated via an enzyme-cleavable linkage with the antigen, antibody, oligonucleotide, or nucleic acid. Reversibly quenched embodiments are also provided in which a cleavable linkage joins a fluorescent phthalocyanine monomer with another phthalocyanine, a heavy metal, or a paramagnetic species.