Used in bioconjugation and click chemistry applications, particularly for site-specific protein or peptide modification. Its bis-sulfone group reacts selectively with thiol groups on cysteine residues, enabling stable linkage to biomolecules. The PEG3 spacer improves solubility and provides flexibility, reducing steric hindrance in conjugates. The azide group allows downstream coupling via copper-catalyzed or strain-promoted azide-alkyne cycloaddition (CuAAC or SPAAC), making it useful in labeling, drug delivery systems, and the construction of antibody-drug conjugates (ADCs). Also applied in surface functionalization of nanoparticles and biosensors where controlled orientation and spacing of biomolecules are required.