Used primarily in bioconjugation and protein modification, it serves as a linker to attach polyethylene glycol (PEG) chains to biomolecules like proteins, peptides, or antibodies. This process, known as PEGylation, enhances the stability, solubility, and half-life of therapeutic proteins in the body, reducing immunogenicity and improving drug delivery efficiency. It is also applied in the development of diagnostic tools and research reagents, where controlled and specific conjugation is required. Its NHS ester group ensures efficient and selective reactions with amine-containing molecules under mild conditions.