Azido-PEG3-aldehyde is widely used in bioconjugation and chemical biology due to its reactive azide and aldehyde functional groups. The azide group allows for click chemistry reactions, particularly copper-catalyzed azide-alkyne cycloaddition (CuAAC), enabling the attachment of biomolecules or probes. The aldehyde group facilitates Schiff base formation with amines, making it useful for labeling proteins, peptides, or other amine-containing molecules. This compound is particularly valuable in the development of drug delivery systems, where it acts as a linker to conjugate therapeutic agents to targeting moieties. It is also employed in surface modification, enabling the functionalization of materials for biosensors or biomedical devices. Additionally, its PEG spacer enhances solubility and reduces steric hindrance, improving the efficiency of conjugation reactions.