Used in bioconjugation for targeted drug delivery, particularly in antibody-drug conjugates (ADCs). The BCN group enables strain-promoted click chemistry with azide-functionalized biomolecules, allowing efficient and selective coupling without catalysts. The PEG3 spacer improves solubility and reduces aggregation, enhancing conjugation efficiency and stability in biological environments. The VC linker is protease-cleavable, enabling controlled release of the payload inside target cells, especially in cancer therapy. The PFP ester reacts with primary amines on proteins or antibodies, forming stable amide bonds, making it ideal for constructing homogeneous ADCs with high therapeutic index.