BioIntersect’s Calcein AM Cell Viability Assay is a very sensitive (~50 cells detection limit) fluorometric assay for assessing cell viability, cytotoxity and proliferation. Calcein AM is a non-fluorescent, hydrophobic compound that penetrates intact and live cells. Intracellular esterase hydrolyzes Calcein AM dye and produces a hydrophilic, strongly fluorescent compound that is retained in the cell cytoplasm and can be measured at Ex/Em = 485/530 nm. The measured fluorescence intensity is proportional to the number of viable cells. BioIntersect’s Calcein AM Cell Viability Assay Kit provides a sensitive, easy-to-do, one-step, non-radioactive and high-throughput assay that takes less than 30 minutes.