Multivalent fluorescent probes

A multivalent fluorescent probe having the structure:

• wherein X and Y are O, S, Se or CR15R16;
• n is 0 to 3;
• R1 to R11 and R13-16 are hydrogen, alkyl having 1 to 20 carbons, alkoxy having 1 to 20 carbons, trifluoromethyl, halogen, methylthio, sulfonyl, carbonyl, hydroxy, amino and thiol;
• wherein R represents a targeting moiety and the four targeting moieties are linked to X, Y, N and N+ via the L1, L2, L3 and L4, wherein L1, L2, L3 and L4 comprise 10 to 50 linear atoms selected from carbon, nitrogen, oxygen, phosphorus and sulfur that are further substituted by hydrogen, alkyl having from 1 to 20 carbons, alkoxy having from 1 to 20 carbons, trifluoromethyl, halogen, methylthio, sulfonyl, carbonyl, hydroxy, amino, thiol, amino acid residues RGD, zinc (Zn) or a ligand that binds to a cell surface receptor;
• wherein the probe emits light having a wavelength of 550 to 1200 nm and wherein the targeting moiety is a molecule that specifically targets the multivalent fluorescent probe to a specific cell.