MAX-Fluor™ Calcein-AM Cell Viability Assay Kit is a fluorescence assay that allows cell viability testing to be performed at a high level of sensitivity comparable to isotopic labeling. The specially designed Calcein cannot penetrate the cell membrane, but Calcein-AM, which is an acetoxymethyl ester bond derivative, freely passes through the cell membrane. The fluorescent Calcein is then separated by intracellular esterase and stays inside the cell. It is measured by fluorescence microscope and FACS (Ex/Em = 490nm/515nm). At this time, the amount of fluorescence measured is determined by the membrane permeability of living cells and the activity of esterase, thus reflecting the activity of the cells. MAX-Fluor™ can be analyzed with much higher sensitivity (30~30,000 cells) than MTZ, MTS, WST and other tetrazolium salt methods. .