Used as an activated ester in bioconjugation reactions, particularly in the development of antibody-drug conjugates (ADCs). It reacts efficiently with primary amines on proteins or antibodies to form stable amide bonds, enabling the site-specific attachment of payloads such as cytotoxic drugs or imaging agents. The disulfide linker provides a controlled release mechanism under reducing conditions, making it suitable for targeted intracellular delivery. Commonly employed in pharmaceutical research for constructing cleavable conjugates with improved therapeutic index.