Used as a hydrophilic linker in bioconjugation, particularly in the development of peptide and protein therapeutics. Its long polyethylene glycol (PEG) chain provides high water solubility and flexibility, improving the pharmacokinetic properties of conjugated molecules. Commonly employed in solid-phase peptide synthesis where the tosyl (Tos) group acts as a protecting group that can be selectively removed. Also utilized in creating spacers between functional groups in assay probes and drug delivery systems to reduce steric hindrance and enhance binding efficiency.