Fmoc-aminooxy-PEG-NHS ester is a compound that belongs to the family of polyethylene glycol (PEG) derivatives. It contains functional groups such as aminooxy and NHS ester, which make it highly reactive and versatile for a range of applications. In pharmaceutical research and development, Fmoc-aminooxy-PEG-NHS ester is used as a linker or spacer molecule for the conjugation of drugs to various carriers such as antibodies, peptides, and proteins. It enables controlled drug release and improves drug efficacy and bioavailability. The Fmoc-protecting group in Fmoc-aminooxy-PEG-NHS ester provides stability during synthesis and purification, and can be easily removed under mild conditions to reveal the aminooxy functional group.