Used in bioconjugation for linking molecules in drug delivery systems, particularly in the development of antibody-drug conjugates (ADCs) and targeted therapies. The azide group enables click chemistry reactions, especially copper-catalyzed azide-alkyne cycloaddition (CuAAC), allowing efficient and selective coupling with alkyne-containing compounds. The PEG2 spacer improves solubility, reduces aggregation, and enhances the pharmacokinetic properties of conjugated molecules. Commonly employed in labeling biomolecules with fluorescent dyes, biotin, or other functional probes for diagnostic and research applications. Also utilized in surface modification of nanoparticles and biosensors due to its ability to form stable, covalent linkages under mild conditions.