Used extensively in biological research for labeling proteins, peptides, and other biomolecules. It serves as a fluorescent marker in fluorescence microscopy, flow cytometry, and immunoassays, enabling visualization and tracking of cellular processes. The succinimidyl ester group facilitates covalent bonding with primary amines, ensuring stable conjugation. It is particularly useful in studying cell viability, membrane integrity, and intracellular pH due to its pH-sensitive fluorescence. Additionally, it aids in monitoring enzyme activity and protein interactions in real-time assays.