Used as a bifunctional crosslinking agent in bioconjugation, particularly for coupling proteins, peptides, or other biomolecules. The NHS ester group reacts efficiently with primary amines (e.g., lysine residues) to form stable amide bonds, while the tert-butyl carbamate (Boc) protected amine can be deprotected under mild acidic conditions and then used for further conjugation or labeling. Commonly applied in the development of antibody-drug conjugates (ADCs), immobilization of biomolecules on surfaces, and synthesis of functionalized polymers or nanoparticles. Its spacer arm provides flexibility and helps reduce steric hindrance, improving reaction efficiency in complex biological systems.