The S-HyNic heterobifunctional crosslinker is fundamental to SoluLink® bioconjugation technology. Sulfo-S-HyNic reacts with primary amines on proteins (through lysine amino acids) or amino-modified oligonucleotides or surfaces, introducing a HyNic linker that forms stable covalent conjugates with biomolecules possessing 4FB linkers. Sulfo-S-HyNic contains a Sulfo-NHS ester, which makes this linker water soluble. No DMF or other organic solvents are necessary to dissolve the linker prior to use.