Cell Counting Kit-8 (CCK-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.
Cell Viability Detection Mechanism with CCK-8
Cell Counting Kit-8 requires 3 simple steps:
The handling time of Cell Counting Kit-8 is the shortest among its competitors. Only 15 minutes of handling time is needed for Cell Counting Kit-8, whereas longer handling time is required for both MTS and MTT assay.
Unlike MTT assay, there is no need to lyse cells, so you don’t have to worry about the data variation.
CCK-8 (WST-8) is the highest sensitive dye for the cell based assay.
MTT Users, Click Here for differences between CCK-8 and MTT
Sensitivity Comparison using Tetrazolium Dye
Cytotoxicity of Reagents
Only in CCK-8, continuous culture is possible without killing cells.
Observation of Cytotoxicity after incubation with each reagent.
HeLa cells were incubated with WST-8 (CCK-8), WST-1, or MTS at 24 hours from addition of those reagents.
Cell Counting Kit-8 is a ready-to-use solution stable at 4ºC for 1 year. Assays can be completed anytime without thawing and freezing.
Simultaneous usage of CCK-8 and Cytotoxicity LDH Assay Kit-WST
Since Cell Counting Kit-8 measures the metabolic activity of living cells, the data does not specifically verify cell death. To ensure the data is reflecting the cell death instead of decreased metabolic activity, Cytotoxicity LDH Assay Kit-WST (CK12) is used to increase the data reliability by measuring LDH released from dead cells.
Example Data using Cell Counting Kit-8
Data for Cell Proliferation and Cytotoxicity Assay
Cell Viability Determination
Data was kindly provided by Reaction Biology Corporation.
Absorption property of WST-8
The microplate reader with a 450-490 nm filter is applicable for the measurement.
Absorption spectrum of WST-8 formazan dye
Cell Counting Kit-8 (CCK-8) used for Viral Research
1. CCK-8 is used to evaluate antiviral activity of potent compounds against virus infection. In Dr. Xia’s research work, each virus (SARS-CoV-2, MERS-CoV, HCoV-OC43, HCoV-229E and HCoV-NL63) was treated with the optimized peptide and then the mixture was added to the cells. They used the CCK-8 to assess the antiviral activity of the peptide. Also, cytotoxicity of the peptide to the cells was measured by the CCK-8*1. The CCK-8 is a useful tool to support developing antiviral agent against virus infection.
“Inhibition of SARS-CoV-2 (previously 2019-nCoV) infection by a highly potent pan-coronavirus fusion inhibitor targeting its spike protein that harbors a high capacity to mediate membrane fusion” , S. Xia, et al., Cell Research, 2020, 30, 343–355
2. It has been reported that the extracts of S. baicalensis have anti-viral activities.
Dr. Liu et.al, determined the cytotoxicity of baicalensis extract and baicalein on Vero cells using CCK-8 in order to evaluate the antiviral efficiency of them against SARS-COV-2 virus.
“Scutellaria baicalensis extract and baicalein inhibit replication of SARS-CoV-2 and its 3C-like protease in vitro” , H. Liu, et al., bioRxiv, 2020.
3. Dr. Chen et al., evaluated the cytotoxicities and inhibitory activities of antiviral compounds (lycorine and brequinar) in Vero, A549 and Huh7 cells using CCK-8 in Zika virus research.
“ Antiviral activity of lycorine against Zika virus in vivo and in vitro” , H. Chen, et al., Virology, 2020, 546, 88-97.
4. Dr. Abdull et. al used AI-based platform to develop combination therapy for infection disease. They choose multiple drugs. CCK-8 was used to evaluate drug-induced cytotoxicity in A549 cells.
“Project IDentif.AI: Harnessing Artificial Intelligence to Rapidly Optimize Combination Therapy Development for Infectious Disease Intervention” , A. Abdulla et.al, Adv. Ther., 2020, doi.org/10.1002/adtp.202000034
5. Dr. Wu et al., aimed to identify Single-Domain Antibodies against SARS-CoV-2. Vero E6 cells was used in the evaluation of viral cytopathic effect (CPE)-based neutralization.CCK-8 was used to assess cell viability.
“Identification of Human Single-Domain Antibodies Against SARS-CoV-2” , Y.Wu et.al, Cell Host Microbe., 2020, doi: 10.1016/j.chom.2020.04.023