Propargyl-PEG7-acid is widely used in bioconjugation and click chemistry applications due to its terminal alkyne group and polyethylene glycol (PEG) spacer. The alkyne group enables efficient coupling with azide-containing molecules via copper-catalyzed azide-alkyne cycloaddition (CuAAC), making it valuable for labeling biomolecules such as proteins, peptides, and nucleic acids. The PEG7 spacer enhances solubility and reduces steric hindrance, improving reaction efficiency and biocompatibility. This compound is particularly useful in drug delivery systems, where it facilitates the attachment of therapeutic agents to targeting moieties. It is also employed in the development of biosensors, diagnostic tools, and materials science for surface modification and functionalization. Its versatility and water solubility make it a key reagent in pharmaceutical research and biotechnology.