Used as a bifunctional linker in bioconjugation, particularly in antibody-drug conjugates (ADCs) and peptide coupling. Its terminal carboxylic acid group allows for easy activation and amide bond formation with amines, while the maleimide ring selectively reacts with thiol groups (-SH) in cysteine residues under mild conditions. This enables precise attachment of drugs, labels, or polymers to proteins and biomolecules. Commonly applied in pharmaceutical development for targeted therapies, where controlled and stable linkage is critical. Also utilized in surface functionalization of nanoparticles and hydrogels for drug delivery and diagnostic applications.