Fluo-Forte Calcium Assay Kits detect mobilization of intracellular calcium utilizing a fluorogenic calcium-binding dye optimized for superior cell-permeability and retention. The self-quenching dye undergoes an electronic change upon binding of calcium, resulting in a several order of magnitude greater fluorescence. Mechanism of Action The fluorogenic calcium-binding dye is provided to the cells as an acetoxymethyl (AM) ester, which is cell-permeable. Once inside the cells, the dye is hydrolyzed by intracellular esterases, which leads to generation of a cell membrane impermeable negatively charged form. In the absence of calcium, the calcium-binding moiety portion of the probe quenches the fluorescence of the fluorophore portion of the probe by photo-induced electron transfer. Applications: Flow Cytometry, Fluorescence microscopy, Fluorescent detection, HTS .