Difluorocarboxyfluorescein-488 NHS Ester 5-isome

2‘,7‘-Difluorofluorescein-5-carboxy-NHS ester 488 (DFCF-488, NHS), is an amine-reactive fluorescent dye with a high molar extinction coefficient (ε = 72,000 M⁻¹cm⁻¹), enabling efficient covalent conjugation to antibodies, peptides, proteins, and nucleic acid tracers at pH 7.5-8.5 or lower. With a pKa of ~4.7 and λₑₓ/λₑₘ ~ 490/520 nm, DFCF-488 offers high quantum yield, photostability, and pH-independent fluorescence in physiological conditions, making it ideal for calcium monitoring and pH tracking in acidic organelles and pathways. DFCF-488 conjugates support diverse applications, including live-cell imaging, FRET-based biosensing, high-throughput screening, and immunofluorescence, ensuring reliable performance for cellular labeling and detection.