Patent ID: 8664396

Claim:
A method of staining a poly(amino acid), comprising contacting the poly(amino acid) with a metal complex comprising: (i) at least one metal ion; and (ii) a plurality of donor ligands each fully coordinated to the metal ion and each independently selected from the group consisting of a nitrogen donor ligand and a cyclometalated donor ligand, wherein at least one of the donor ligands is a cyclometalated donor ligand; wherein: each nitrogen donor ligand comprises a heteroaryl ring system having from 10 to 40 ring atoms, wherein from 2 to 8 ring atoms are each independently selected from the group consisting of N, O and S, wherein at least two ring atoms are N, and wherein each nitrogen donor ligand is substituted with from 0 to 4 R 1 groups; each cyclometalated donor ligand is a member selected from the group consisting of: each R 1 is independently selected from the group consisting of C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, C 1-6 alkoxy, halogen, C 1-6 haloalkyl, —OR 2 , —NR 2 R 3 , —CN, —C(O)R 2 , —OC(O)R 2 , —C(O)NR 2 R 3 , —N(R 2 )C(O)R 3 , —OC(O)NR 2 R 3 , —NR 2 C(O)NR 3 R 4 , —NR 2 C(S)NR 3 R 4 , —NO 2 , ═O, aryl, heteroaryl, cycloalkyl and heterocycloalkyl; and each R 2 , R 3 and R 4 are independently selected from the group consisting of H and C 1-12 alkyl; wherein the poly(amino acid) is present in a sample mixture on or in an SDS-PAGE gel, and wherein said metal complex is cationic in overall electronic charge, to achieve non-covalent association of said metal complex with the poly(amino acid) and to thereby stain the poly(amino acid).