Propargyl-PEG7-NHS ester is widely used in bioconjugation and chemical biology for attaching biomolecules to various surfaces or other molecules. Its propargyl group enables click chemistry reactions, particularly copper-catalyzed azide-alkyne cycloaddition (CuAAC), allowing for efficient and selective coupling with azide-containing compounds. The NHS ester moiety facilitates the covalent attachment to primary amines, making it ideal for labeling proteins, peptides, or antibodies. This compound is valuable in drug delivery systems, where it helps create targeted conjugates for improved therapeutic efficacy. It is also utilized in the development of biosensors, diagnostic tools, and functionalized nanoparticles, enhancing their specificity and performance. Additionally, its PEG spacer improves solubility and reduces immunogenicity, making it suitable for in vivo applications.