If the answer is yes, you still use MTT or WST-1 to count cells,  I am sure you’ll be interested to learn more about WST-8 and our Cell Counting Kit-8 (CCK-8). If the answer is no, and you’ve already switched to WST-8, just have a look at our price list… you might be surprised!

CK04_fig1CCK-8 allows sensitive colorimetric assays for the determination of cell viability in cell proliferation and cytotoxicity assays. Dojindo’s highly water-soluble tetrazolium salt, WST-8, is reduced by dehydrogenase activities in cells to give a yellow-color formazan dye, which is soluble in the tissue culture media. The amount of the formazan dye, generated by the activities of dehydrogenases in cells, is directly proportional to the number of living cells. The detection sensitivity of CCK-8 is higher than the other tetrazolium salts such as MTT, XTT, MTS or WST-1.

What are the 4 main benefits for you? (to keep it short!)

  • No toxicity to cells
  • More sensitive than MTT, MTS, or WST-1
  • 3 simple steps (no thawing necessary): Add – Incubate – Measure
  • More stable than MTT, MTS or WST-1

Keep on reading for more details about each of these benefits…

Count cells in 3 steps with CCK-8


The handling time of CCK-8 is the shortest compared to its competitors. You’ll only need 15 minutes of handling time with CCK-8, whereas longer handling time is required for both MTS and MTT assays.


Unlike MTT assays, since there is no need to lyse the cells, you don’t have to worry about data variation.


CCK-8 is a ready-to-use solution and it’s also stable at 4ºC for 1 year. Your assay can be done anytime without thawing and freezing.


CCK-8 is the highest sensitive dye for cell based assays.


Only in CCK-8 is continuous culture possible without killing cells. Below are illustrations observing Cytotoxicity after incubation with each reagent. HeLa cells were incubated with WST-8 (CCK-8 ), WST-1, or MTS and observed at 24 hours after addition of these reagents.


Well, since you’ve read this post right through to the end, I’m pleased to share this short cartoon about the Cell Counting Kit-8 (CCK-8) with you!

Written by Jean-François Têtu, PhD
Jean-François Têtu is Sales & Marketing Manager at Tebubio. He also fervently defends and promotes anything from his home territory, the north of France!