NSP offers heterobifunctional Folate-PEG-Amine (Folate-PEG-NH2, Folic acid-PEG-NH2) with high quality. Folic acid, or vitamin B9, can selectively bind to folate receptor, while Primary amine can react with a variety of functional groups such as succinimidyl ester (NHS), carboxylic acids (COOH), anhydride and many others. The PEG moiety in the heterofunctional PEG derivatives provides water solubility, biocompatibility, and flexibility. This reaction allows attachment of folic acid ligand to proteins, antibodies, peptides or particle surfaces. Folic acid functionalized substrates have been used for targeted drug delivery, imaging, and bioassay development.