S-4FB Linker (DMF Soluble), 10 mg. S-4FB heterobifunctional crosslinker is fundamental to SoluLINK bioconjugation technology. S-4FB reacts with primary amines on proteins (through lysine amino acids) or amino-modified oligonucleotides or surfaces, introducing a 4FB linker that forms stable covalent conjugates with biomolecules possessing HyNic linkers.