Used as a crosslinking agent in bioconjugation, particularly for coupling antibodies or proteins to fluorescent dyes, enzymes, or other labeling molecules. Its NHS ester group reacts efficiently with primary amines on biomolecules, forming stable amide bonds. The 2,4-dinitroaniline moiety acts as a chromophore, allowing for spectrophotometric monitoring of the conjugation reaction. Commonly applied in the development of immunoassays, diagnostic probes, and targeted imaging agents. The hexanoate spacer provides flexibility and helps reduce steric hindrance, improving reaction efficiency and preserving the biological activity of the conjugated molecules.