Used in bioconjugation and chemical synthesis, it serves as a linker to attach functional groups or molecules to biomolecules like proteins, peptides, or antibodies. Its azide group enables click chemistry reactions, particularly with alkyne-containing compounds, facilitating efficient and selective modifications. The PEG spacer enhances solubility and reduces steric hindrance, making it suitable for applications in drug delivery, diagnostics, and material science. The reactive ester group allows for covalent attachment to amine-containing molecules, enabling the creation of stable conjugates. Commonly employed in the development of targeted therapeutics, biosensors, and advanced polymer materials.