WST-8

WST-8 (2-(2-methoxy-4-nitrophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H tetrazolium, monosodium salt), a highly stable and water-soluble WST, is utilized incell Counting Kit-8 (CCK-8).It is more sensitive than WST-1 particularly at neutralpH. Because of the electron mediator, 1-methoxy PMSin this kit is highly stable, and CCK-8 is stable for at least six months at the room temperature and for one year at 0-5°C (asshown in Figure 1).

Advantages: WST-8 is not cell permeable, which results in low cytotoxicity. Therefore,after the assay, it is possible to continue further experiments using the same cells.Furthermore, it produces the water-soluble formazan upon cellular reduction，which would provide an additional advantage to the method by allowing a simpler assay procedure and not required an extra step to dissolve the formazan.
Disadvantages: An important consideration is that reduction of assay substrates isimpacted by changes in intracellular metabolic activity that has no direct effect on over-all cell viability.

Cell Counting Kit-8 (CCK-8) allows very convenient assays by utilizing the highly water-soluble tetrazolium salt WST-8 [2-(2-methoxy-4-nitrophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2Htetrazolium,monosodium salt] (Patent No. WO97/38985) produces a water-soluble formazan dye upon reduction in the presence of an electron carrier. Cell Counting Kit-8 is a onebottle solution; no premixing of components is required. Cell Counting Kit-8, being nonradioactive, allows sensitive colorimetric assays for the determination of the number of viable cells in cell proliferation and cytotoxicity assays. WST-8 is reduced by dehydrogenases in cells to give a yellowcolored product (formazan), which is soluble in the tissue culture medium. The amount of the formazan dye generated by the activity of dehydrogenases in cells is directly proportional to the number of living cells. The detection sensitivity of CCK-8 is higher than other tetrazolium salts such as MTT, XTT, MTS or WST-1.

A highly sensitive tetrazolium reagent that produces a water-soluble formazan (orange color that absorbs at 460 nm) in NADH. It is newer generation formazan-based dyes which release the converted prod uct into the medium in a soluble form allowing for a non-destructive determination of viability enabling the cells to be subject to further investigations.

WST-8 is a next generation tetrazolium reagent that serves as a sensitive chromogenic indicator for NADH.

WST-8 is a next generation tetrazolium reagent that serves as a sensitive chromogenic indicator for NADH. It is reduced by NADH at neutral pHs in the presence of 1-methoxy PMS to produce the corresponding formazan dye that absorbs at 460 nM. Useful as a cell viability indicator in cell proliferation assays.