What is the principle of the MTT assay for detecting cell viability?

MTT assay is a commonly used method for detecting cell viability. Its principle involves the use of MTT fluorescent dye, which enters cells and is reduced by intracellular metabolic products into purple formazan crystals. The cell survival rate and metabolic activity can then be determined by measuring the absorbance spectrum of this formazan product. The procedure typically includes steps such as cell treatment, addition of MTT dye, cellular reduction of the dye, cell lysis, and absorbance measurement.

1. Cell treatment: Cultivate the target cells in culture medium containing the test substance, or treat cells under different experimental conditions separately.

2. Addition of MTT dye: Add a certain concentration of MTT fluorescent dye to the cell culture medium. The MTT dye penetrates the cell membrane and enters the cells.

3. Cellular reduction of MTT dye: Inside the cells, the MTT dye is reduced by metabolic enzymes into purple formazan crystals.

4. Cell lysis: Add a solvent to lyse the cells and dissolve the resulting purple formazan crystals into the culture medium.

5. Absorbance measurement: Use a microplate reader to measure the absorbance of the solution. The absorbance value of the purple formazan product is directly proportional to the cell viability and metabolic activity. By measuring the absorbance of the reduced MTT product within the wavelength range of 570–630 nm, cell viability and survival rate can be calculated.

The MTT assay infers cell viability and metabolic activity by measuring the absorbance spectrum of the purple formazan product. It is a convenient, straightforward, and rapid method in cell biology research. Patients are advised to undergo this test at正规 medical institutions.