Used as a bifunctional crosslinking agent in bioconjugation, particularly for coupling proteins, peptides, or other biomolecules. Its dual NHS ester groups react efficiently with primary amines (e.g., lysine residues) under mild aqueous conditions, enabling stable amide bond formation. The central disulfide linker provides cleavability under reducing conditions, making it useful in drug delivery systems where intracellular release is desired, such as in antibody-drug conjugates (ADCs). Also applied in immobilizing biomolecules onto surfaces for biosensors or diagnostic assays due to its water solubility and controlled reactivity.