Azido-PEG9-amine is widely used in bioconjugation and click chemistry applications due to its azide functional group, which allows for efficient and selective reactions with alkynes. It serves as a linker molecule in the development of drug delivery systems, enabling the attachment of therapeutic agents to targeting molecules or nanoparticles. This chemical is also employed in the modification of biomolecules, such as proteins and peptides, to enhance their stability, solubility, or functionality. Additionally, it plays a role in surface functionalization for materials science, where it helps create bioactive coatings on medical devices or sensors. Its PEG (polyethylene glycol) spacer provides water solubility and reduces immunogenicity, making it suitable for biomedical and pharmaceutical research.