Fura-2, AM ester is an intracellular fluorescent calcium indicator, and the preferred dye for ratiometric imaging microscopy. The membrane-permeant AM ester can be loaded into cells via incubation, but due to limited water solubility, a mild detergent Pluronic F-127 is often used to facilitate cell loading. Fura-2, AM ester itself does not bind Ca2, but intracellular esterases readily hydrolyze it to Fura-2. Upon calcium binding, the excitation maximum of Fura-2 undergoes a blue-shift from 363 nm (no Ca2) to 335 nm (high Ca2) while the emission maximum is relatively unchanged. Measure by flow cytometry, fluorescence microscopy, or certain fluoresence microplate readers. Properties: Light yellow solid soluble in DMSO; Store at -20°C, protect from light, especially in solution; Kd: 145 nM (22°C, pH 7.2 buffer); Ex/Em = 363/512 nm, e = 27,000 M-1cm-1 (no Ca2); Ex/Em 335/505 nm, e = 35,000 M-1cm-1 (high Ca2); C44H47N3O24; MW: 1001.9; [108964-32-5].