Cell Counting Kit-8 (CCK-8 kit) is a kit for detecting cell proliferation and cytotoxicity developed by Japan Dojindo Chemical Research Institute (Dojindo). It is an alternative to the MTT method. CCK- 8 The kit uses the tetrazolium salt developed by Japan Dojindo Chemical Research Institute (Dojindo) - WST-8 (2-(2-methoxy-4-niphenyl)-3-(4-niphenyl)- 5-(2,4-disulfobenzene)-2H-tetrazole monosodium salt), holds patents in Japan, the United States, Europe and other countries and regions. Tongren Chemical Research Institute obtained WST registration in China in 2006 trademark.

WST-8 can be reduced to water-soluble formazan dye in the presence of the electron carrier 1-Methoxy PMS. CCK-8 solution can be added directly to cell samples without pre-preparing various ingredients. The CCK-8 method is a highly sensitive, non-radioactive, colorimetric detection method used to determine the number of viable cells in cell proliferation or cytotoxicity tests. The orange formazan dye generated after CCK-8 is bioreduced by intracellular dehydrogenase can be dissolved in tissue culture medium, and the amount of formazan generated is proportional to the number of viable cells. The WST-8 method is more sensitive than other tetrazolium salts such as MTT, XTT, MTS or WST-1 for detecting cell proliferation and cytotoxicity. Since the CCK-8 solution is quite stable and non-toxic to cells, it can be incubated for long periods of time.

Compared with the ordinary MTT method, the CCK-8 method has significant characteristics:

★High sensitivity, reliable data, and good reproducibility

Easy to operate , saving time and effort

★Water-soluble, no need to change the medium, especially suitable for suspended cells

★No need for radioactive isotopes and organic solvents, low toxicity to cells

★One bottle of solution, no pre-preparation required, ready to use

★Suitable for high-throughput drug screening