Used in bioconjugation to link molecules via alkyne-amine reactions, particularly in click chemistry applications. The PEG4 spacer enhances solubility and reduces steric hindrance, improving reaction efficiency. Commonly employed in labeling peptides, proteins, and antibodies with fluorescent dyes, biotin, or other detection tags. Suitable for creating stable amide bonds with primary amines under mild conditions, making it ideal for sensitive biomolecules. Frequently used in drug discovery, diagnostic assays, and development of bioconjugates for research and therapeutic purposes.