Used primarily as a coupling agent in bioconjugation chemistry, this compound enables efficient attachment of biomolecules such as peptides, proteins, or antibodies to other functional molecules or surfaces. Its activated ester group reacts selectively with primary amines under mild conditions, forming stable amide bonds. The presence of a nitrophenyl diazenyl chromophore provides a visible color change, allowing for real-time monitoring of conjugation reactions. This feature is particularly useful in diagnostic assays and labeling applications where confirmation of coupling is essential. It is commonly employed in the development of immunoassays, biosensors, and targeted drug delivery systems.