N-Succinimidyl-(3-(2-Pyridyldithio)propionate) Hexanate is a heterobifunctional crosslinking agent widely used in bioconjugation and protein labeling applications. The N-hydroxysuccinimide (NHS) ester reacts specifically with primary amine groups on proteins, peptides, or antibodies (e.g., lysine residues), thereby installing a pyridyldithio (PDT) group. The PDT group then enables selective conjugation of thiol-containing molecules to these amine-modified biomolecules or surfaces through reversible disulfide bond formation under reducing conditions. This reversibility is particularly useful in drug delivery systems, where controlled release of therapeutic agents is required. Additionally, it is employed in the development of diagnostic assays, where precise labeling of biomolecules is essential for detection and analysis. Its stability and reactivity make it a valuable tool in biochemical research and therapeutic development.