Since its creation in 1983 (1), the MTT assay has been widely used for assaying cell viability, proliferation, and measuring the cytotoxicity of test compounds. MTT is one of several tetrazolium salts that have been used for assessing metabolic activity of cells, however it is the only one that is positively charged and therefore can readily be taken up by eukaryotic cells.
The MTT assay is a colorimetric assay that utilizes the reduction of MTT by NADH (and presumably other reducing molecules) to form an insoluble formazan product, resulting in a color shift from yellow to purple. Formazan accumulates both inside cells and on the cell surface and must be solubilized before the concentration of formazan in samples can be determined by reading OD values at 570 nm. For cells in log phase growth, the formazan concentration is directly proportional to the number of metabolically active (viable) cells in the sample, since dead cells are unable to reduce MTT to formazan. The amount of formazan produced in any given assay depends on a few variables, including: concentration of MTT, incubation period length, the metabolic activity of specific cell types, and the number of viable cells. These factors should be considered when optimizing the assay for your unique purposes.
Since the reduction of MTT to formazan requires active cell metabolism, Chondrex, Inc.’s MTT Cell Proliferation and Viability Assay Kit is ideal for determining the cytotoxicity of test compounds and the viability of cells within a sample. Please see our protocol for more information.
If you would like to try our MTT Cell Proliferation and Viability Assay Kit, please do not forget to ask about our 50% trial discount!