Fluorescence cell viability assay

Haugland, R. R MacCoubrey, I. C. Moore, P. L. Dual-fluorescence cell viability assay using ethidium homodimer and calcein AM. U.S. Patent 5314805, 1994 Chem. Abstr. 1994, 121, 53487. 

The modem ATP assay has become the HTS method of choice to measure cell viability. It is the fastest and most sensitive assay and is less prone to artifacts than fluorescent methods. A growing list... 

This same procedure can also be used in microscopy or FACS analysis coupled with a nuclear dye such as ethidium homodimer-1, a red fluorescent nucleic acid stain (ex/em 495/ 635 nm) that is only able to pass through the compromised membranes of dead cells, and indicates the proportion of live vs. dead cells. (The viability assay kit including calcein-AM and ethidium homodimer-1 is sold by Molecular Probes, Cat. L-3224.)... 

This assay is used to measure cell viability. It is a two-color fluorescence assay that simultaneously determines live (viable) and dead (nonviable) cells Live cells have intracellular esterases that convert nonfluorescent, cell-permeable fluorescein di-O-acetate to the intensely fluorescent fluorescein (green). Cleaved fluorescein is retained within cells. Dead cells have damaged membranes propidium iodide enters damaged cells and is fluorescent when bound to nucleic acids. It produces a bright red fluorescence in damaged or dead cells. 

Live/dead cell cytotoxicity assay A measurement technique to quantify cell viability though the amount of live and dead cells within the culture. Only live cells uptake calcein which is hydrolyzed by intracellular esterases to fluoresce green. Only cells with a compromised cell membrane (dead or dying cells) can uptake ethidium which binds to DNA to fluoresce red... 

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