Used in bioconjugation and bioorthogonal chemistry, this compound enables selective labeling and detection of biomolecules in complex biological environments. Its azide group participates in copper-catalyzed or strain-promoted azide-alkyne cycloaddition (click chemistry), allowing efficient attachment to alkyne-modified targets such as proteins, peptides, or nucleic acids. The polyethylene glycol (PEG) linker enhances solubility and reduces non-specific binding, improving performance in aqueous systems. The carboxylic acid group, often activated, facilitates covalent coupling to amine-containing molecules. The terminal amino group on the ethyl chain provides additional versatility for conjugation, such as with activated esters or other electrophiles. Commonly applied in the development of diagnostic probes, targeted therapeutics, and fluorescent labeling strategies, especially in live-cell imaging and proteomics research. The sodium salt form improves stability and handling in laboratory settings.