Azidoacetic acid NHS ester is widely used in bioconjugation chemistry due to its reactive NHS ester group, which enables efficient coupling with primary amines in proteins, peptides, and other biomolecules. This compound is particularly valuable in click chemistry applications, where the azide group can participate in copper-catalyzed azide-alkyne cycloaddition (CuAAC) reactions. This allows for the labeling, modification, or crosslinking of biomolecules with high specificity and efficiency. It is commonly employed in the development of antibody-drug conjugates, fluorescent probes, and biotinylation of proteins for various research and diagnostic purposes. Additionally, its stability and reactivity make it a preferred choice for creating functionalized surfaces in material science and bioengineering.