Calcein AM is a cell-permeable dye that can be used to determine the viability of most eukaryotic cells. In living cells, non-fluorescent calcein AM is converted into green fluorescent calcein after intracellular esterase hydrolyzes acetoxymethyl ester. We also offer this dye as a 1 mg solid (C-1430) and a resuspended solution in DMSO (C-3099). This dye is also available in models with longer wavelengths. For detailed information, please view the latest CellTrace calcein red-orange AM (C-34851).