Widely used in bioconjugation, this fluorescent dye is ideal for labeling proteins, antibodies, peptides, and other biomolecules containing primary amines. Its near-infrared emission allows deep tissue imaging with minimal background autofluorescence, making it highly suitable for in vivo imaging, small animal studies, and fluorescence-based assays. Commonly applied in flow cytometry, immunohistochemistry, and Western blotting, it enables sensitive detection and multiplexing when combined with other fluorophores. The NHS ester group ensures efficient and stable amide bond formation under mild reaction conditions, enhancing labeling consistency and performance in downstream applications.