Used as a heterobifunctional crosslinking agent in bioconjugation, particularly for linking proteins, peptides, or antibodies to other molecules such as enzymes, fluorescent dyes, or biotin. The maleimide group reacts selectively with thiol groups (-SH), while the NHS ester reacts efficiently with primary amines (-NH2), enabling stable linkage between two biomolecules. Commonly applied in the development of antibody-drug conjugates (ADCs), immunoassays, and labeling of proteins for detection or purification. Its water-soluble properties make it suitable for reactions in aqueous buffers without organic solvents, improving compatibility with biological systems.