– ‘O’-(carboxymethyl)fluoresceinamide is a multifunctional dye used in biological experiments to observe and analyze cell structures, track biomolecules, evaluate cell functions, distinguish cell types, detect biomolecules, study tissue pathology, and monitor microorganisms. It has applications in basic research, clinical diagnostics, textile dyeing, functional textile processing, food pigments, and dye-sensitized solar cells.