Used as a fluorescent probe in biological imaging and sensing applications due to its strong fluorescence and pH sensitivity. Its carboxyl group allows for easy conjugation to biomolecules such as proteins, antibodies, and nucleic acids, making it useful in immunoassays and fluorescence labeling. Also employed in the development of fluorescent sensors for metal ions and in monitoring enzymatic activity, particularly esterases and proteases, where changes in fluorescence signal indicate reaction progress. Commonly used in microscopy and flow cytometry for cell tracking and viability studies.