Screen Quest™ Fura-2 No Wash Calcium Assay Kit monitors intracellular calcium changes using the ratiometric indicator Fura-2. The cell-permeable acetoxymethyl (AM) ester enters cells, where intracellular esterases cleave the AM groups to generate a charged calcium-responsive indicator. Calcium binding shifts the excitation spectrum toward shorter wavelengths, increasing fluorescence with 340 nm excitation and decreasing fluorescence with 380 nm excitation. The resulting 340/380 fluorescence ratio provides a readout of intracellular calcium changes.

The homogeneous no-wash format supports 96-well and 384-well microplates and automated detection, with recommended excitation settings of 340 and 380 nm and emission detection at 510 nm. The kit supports high-throughput screening of calcium-coupled GPCRs and functional studies of calcium channels.