Folic acid PEG Maleimide, also called Folate PEG Maleimide, is one of Nanocs sulfhydryl (thiol) reactive folic acid PEG derivatives. Maleimide group reacts with sulfhdyl (-SH) in pH 6.5-7.5 quickly and efficiently. This reaction allows attachment of folic acid ligand to proteins, antibodies, peptides or particle surfaces. Pegylated folic acid has relatively good water solubility and bioactivity. Folic acid functionalized substrates have been used for targeted drug delivery, imaging, and bioassay development.