Aminooxy-PEG3-propargyl is widely used in bioconjugation and chemical biology for labeling and modifying biomolecules. Its aminooxy group reacts selectively with carbonyl compounds, such as aldehydes and ketones, enabling the attachment of molecules to proteins, peptides, or other biomolecules. The propargyl group allows for further functionalization via click chemistry, particularly copper-catalyzed azide-alkyne cycloaddition (CuAAC), making it a versatile linker in drug delivery systems, antibody-drug conjugates, and fluorescent labeling applications. Its PEG spacer enhances solubility and reduces steric hindrance, improving the efficiency of conjugation reactions. This compound is also employed in the development of targeted therapeutics and diagnostic probes, facilitating precise and controlled modifications in complex biological systems.