Used as a fluorescent probe in biological imaging due to its ability to emit strong red fluorescence in aqueous environments. Particularly effective for staining cell membranes and tracking membrane dynamics in live cells. Its carboxylic acid group allows for conjugation with biomolecules such as proteins and peptides, making it useful in immunoassays and receptor labeling. Also applied in photodynamic therapy research owing to its light-responsive properties and stability under physiological conditions.