Cell counting Kit-8 or CCK-8 is used to determine the viability of a cell in cell proliferation cytotoxicity assays. It utilizes a water-soluble tetrazolium salt know as WST-8 which gives a water-soluble dye after shrinking in the presence of an electron. This kit is a single-bottle solution.
It does not require any premixing of components. This kit is nonradioactive in nature which allows sensitive colorimetric assays to help in determining the viability of a cell. WST-8 is extracted from dehydrogenase activities in the cells to provide a colored formazan dye, which can be used as a soluble in the study of tissue culture. This kit is the highest sensitive dye.
The amount of this formazan dye is directly proportional to the number of cells living. As CCK-8 measures the metabolic activity of living cells, the data provided by this kit does not verify the death of a cell. To get the data about cell death instead of metabolic activity, CK-12 is used that measures the level of LDH released by dead cells.
There are various advantages of CCK-8 which makes it easy to use. It is a ready-to-use solution that does not require any organic solvents or isotopes. It does not require any harvesting or washing as the cells are non-toxic in nature. It is more sensitive than WST-1. But, requires a few precautions that need to be taken when using this kit.
It includes beware of introducing bubbles into the wells as it may interfere with the readings. You need to sterilize the kit with filtration of the membrane. Neutral red or crystal violet is used after the CCK-8 assay. So, you can buy this highly sensitive kit to determine the number of viable cells.