Used extensively as a fluorescent labeling reagent in biochemical and cellular research. It is particularly effective for labeling proteins, peptides, and antibodies due to its reactive succinimidyl ester group, which forms stable amide bonds with primary amines. Its bright fluorescence and photostability make it ideal for fluorescence microscopy, flow cytometry, and other imaging techniques. Commonly applied in tracking cellular processes, protein localization, and molecular interactions. Its high sensitivity allows for detailed visualization in complex biological systems.