Used in bioconjugation processes to link biomolecules, such as proteins or peptides, with other molecules or surfaces. The PEG spacer enhances solubility and reduces immunogenicity, making it valuable in drug delivery systems and therapeutic applications. The NHS ester group facilitates efficient and stable amide bond formation with primary amines, often employed in antibody-drug conjugates, diagnostic assays, and biotechnological research. Its hydrophilic properties also improve biocompatibility and stability in aqueous environments.