5-Carboxyfluorescein dipivaloate

5-Carboxyfluorescein dipivalate is a cell-permeable, non-fluorescent fluorescein derivative that becomes fluorescent inside live cells upon enzymatic cleavage. Once inside the cell, intracellular esterases cleave the pivaloyl groups, releasing fluorescent 5-carboxyfluorescein, which is negatively charged and becomes trapped in the cell. It can be used in viability assays, enzyme activity studies, and cell tracking, especially where selective intracellular fluorescence is required. Spectral data: Ex ~492nm, Em ~517nm (after hydrolysis to 5-carboxyfluorescein). Carboxyfluorescein dipivalates are also useful as synthetic intermediates.