Azido-PEG3-PFP ester is widely used in bioconjugation for linking molecules in a controlled and efficient manner. Its primary application lies in protein labeling and modification, where the PFP ester group reacts selectively with primary amines on proteins or peptides to form stable amide bonds. The azide group enables downstream click chemistry reactions, such as copper-catalyzed azide-alkyne cycloaddition (CuAAC), allowing attachment of fluorescent tags, biotin, or other functional moieties. The PEG3 spacer improves solubility in aqueous systems and reduces steric hindrance, enhancing reaction efficiency and accessibility to target sites. This makes the reagent valuable in developing bioconjugates for diagnostics, targeted drug delivery, and surface immobilization in biosensors. It is also used in constructing complex biomolecular architectures in chemical biology and pharmaceutical research.