Used as a heterobifunctional crosslinking agent in bioconjugation, particularly for coupling proteins or peptides with thiol-containing molecules. One end of the molecule features an NHS ester that reacts efficiently with primary amines (e.g., lysine residues), while the disulfide-linked pyridyl group acts as a thiol-reactive moiety, enabling selective conjugation with cysteine residues or other thiol compounds. The sulfonate group enhances water solubility, making it suitable for use in aqueous reaction buffers without organic solvents. Commonly applied in the development of antibody-drug conjugates (ADCs), immobilization of biomolecules on surfaces, and labeling of proteins with fluorophores or biotin. Its cleavable disulfide bond allows for controlled release of conjugated payloads under reducing conditions, which is beneficial in drug delivery and intracellular release applications.