Widely used in bioconjugation, this compound enables site-specific modification of peptides, proteins, and antibodies by reacting with free thiol groups (-SH) on cysteine residues. Its long PEG chain enhances water solubility and reduces aggregation, making it ideal for improving the pharmacokinetic properties of therapeutic molecules. Commonly applied in the development of antibody-drug conjugates (ADCs), it serves as a linker to attach payloads selectively while maintaining biological activity. Also used in surface functionalization of nanoparticles and hydrogels for drug delivery and diagnostic applications. The extended PEG spacer minimizes steric hindrance, allowing better binding efficiency in complex biological environments.