Biotin-PEG2-Azide is widely used in bioconjugation and labeling applications due to its dual functional groups. The biotin moiety allows strong binding to streptavidin or avidin, which is useful in detection, purification, and immobilization of biomolecules. The azide group enables site-specific conjugation via copper-catalyzed or strain-promoted azide-alkyne cycloaddition (click chemistry), making it ideal for labeling biomolecules in complex biological environments. The PEG2 (short polyethylene glycol) spacer improves solubility, reduces nonspecific binding, and enhances stability in aqueous and biological systems. It is commonly used in proteomics, cell surface labeling, and the development of diagnostic assays and targeted therapeutics.