NutriCulture Live-Dead Cell (Calcein AM/PI) Staining Kit can be used to distinguish dead cells and living cells in mammals with esterase activity. NutriCulture Calcein AM itself has no fluorescence. After entering the cell, it is hydrolyzed by endogenous esterase in the cell to produce Calcein, a polar molecule with strong negative charge and cannot be retained in the cell through the cell membrane, while Calcein can emit strong green fluorescence (Ex/Em = 494nm/517nm). Due to the lack of esterase, dead cells cannot or rarely produce Calcein, so only living cells are stained with strong green fluorescence, and dead cells cannot be stained or stained very weakly. The selective membrane permeability of dead cells is lost, and Propidium Iodide (PI) can enter the cell to specifically bind to double-stranded DNA and produce strong red fluorescence (Ex/Em = 535nm/617nm) to label dead cells. Therefore, the combination of Calcein AM and PI can perform double fluorescence staining on living cells and dead cells at the same time, which can be used for the detection of cell activity and cytotoxicity.