Digoxigenin NHS Ester is an activated ester reagent designed for covalent attachment of digoxigenin (DIG) to amino-containing biomolecules. Digoxigenin is a highly antigenic hapten used in biological detection workflows, similar to other small-molecule tags such as 2,4-dinitrophenol (DNP) and biotin. The NHS ester group reacts with primary amines under mild conditions, enabling DIG labeling of proteins, peptides, amino-modified oligonucleotides, and related biomolecules.

DIG-labeled biomolecules are commonly detected using anti-digoxigenin antibodies with fluorescent, enzyme, or other reporter labels. This labeling strategy is useful for preparing tagged probes or conjugates for immunoassays, nucleic acid detection, hybridization-based assays, and other biological detection applications where anti-DIG antibody recognition provides signal generation.