Cell Counting Kit-8 or CCK-8 is an assay kit used to determine cell viability in cell proliferation and cytotoxicity processes. It is color sensitive in nature. Water-soluble tetrazolium salt and WST-8 is changed by dehydrogenase activities inside the cells to give a yellow-colored formazan dye.
This dye is soluble and used in tissue culture media. The quantity of this dye, generated by dehydrogenases inside the cells, is equal to the number of living cells present inside the given sample. The sensitivity of the cell counting kit (CCK-8) is higher than the other tetrazolium salts such as WST-1 when concerned with detection.
CCK-8 allows assays to be convenient using WST-8 which produces a water-soluble dye. This dye is formed by the biological reduction or bio-reduction in the presence of an electron carrier. Then, the CCK-8 solution is added directly to the cells, without mixing of components prior to the test.
WST-8 is biologically reduced by the process called cellular dehydrogenases in which an orange-colored product is formed that is soluble in nature. The amount of formazan product produced is proportional to the number of living cells. Since the CCK-8 mixture is very stable and has little cytotoxicity, a prolonged incubation for 24 to 48 hours is possible.
CCK8 is a single kit that requires no premixing before the test. Its sensitiveness to colorimetric assay provides correct live cell counting in a cell proliferation application. CCK8 based assay provides excellent relation results of traditional radioactive named thymidine incorporation assay.