MTT cell proliferation assays require cellular metabolism to turn over the reagent, and thus only live cells will be counted. Is this true for CyQUANT Direct as well?
This is true for MTT (as well as XTT, AlamarBlue Cell Viability Reagent, and PrestoBlue Cell Viability Reagent). CyQUANT Direct will also only count live cells, but for a different reason. The dye is a green-fluorescent nucleic acid stain, which will bind to DNA in all cells, live or dead, without the need for cellular metabolism. However, there is a cell impermeant quenching reagent in the kit which will quench both extracellular fluorescence (and thus this is a no-wash assay) and the fluorescence in dead cells (but not live cells).
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If I used XTT (Cat. No. X6493) with an electron coupling reagent, would I get the same results as if I used the CyQUANT XTT Cell Viability Assay kit (Cat. No. X12223)?
Both products use the same reagent, XTT. In theory, the results of any optimized assay using XTT (Cat. No. X6493) may be comparable to using the CyQUANT XTT Cell Viability Assay kit (Cat. No. X12223). Variations may arise due to the type of electron coupling reagent used, the final concentration of XTT, and any assay-specific requirements of the solutions used in resolubilizing the reagents.
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When should I use the XTT reagent alone (Cat No. X6493) versus the CyQUANT XTT Cell Viability Assay (Cat No. X12223)?
For the CyQUANT XTT Cell Viability Assay kit (Cat No. X12223), the amount of reagents, the formulation of the solutions, and the identity of the Electron Coupling Reagent are proprietary information. On the other hand, XTT (Cat. No. X6493) may be resolubilized in either water, buffer, media, or DMSO to a desired stock concentration. We would recommend using XTT, Cat No. X6493 if you need to optimize the final working concentration, if the type of buffer/solvent used to resolubilize the reagent is critical to the study, if you elect not to use an electron coupling reagent, or if you'd like to use a known electron coupling reagent of a defined concentration.
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What is the difference between XTT (Cat No. X6493) and CyQUANT XTT Cell Viability Assay (Cat No. X12223)?
XTT (Cat No. X6493) is 100 mg of XTT in solid form; you must resolubilize this into an aqueous solution or DMSO prior to use.
CyQUANT XTT Cell Viability Assay (Cat No. X12223) is a kit that provides two components: 10 vials each of the XTT Reagent and Electron Coupling Reagent. Both kit components are in solution in a ready-to-use format; mix 1 vial of the XTT Reagent and 1 vial of the Electron Coupling Reagent immediately before use.
Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.
