Azido-PEG3-MS is widely used in bioconjugation and click chemistry applications due to its azide functional group, which enables efficient and selective reactions with alkyne-containing compounds via copper-catalyzed azide-alkyne cycloaddition (CuAAC). It is particularly valuable in the modification of biomolecules, such as proteins, peptides, and antibodies, for labeling, imaging, or drug delivery purposes. The PEG3 spacer enhances solubility and reduces steric hindrance, improving the efficiency of the conjugation process. Additionally, it is employed in the development of bioconjugates for targeted therapies, diagnostics, and research tools in fields like molecular biology, biochemistry, and material science.