Monitoring alterations in cell viability is an essential tool for the evaluation of cell health and proliferation. The Xpert Blue Cell Viability Assay offers a simple, fast and sensitive method for the detection of cellular metabolic activity. This assay is based on the irreversible reduction of the blue, nonfluorescent and nontoxic dye Resazurin into pink and highly-fluorescent Resorufin by diaphorase-type enzymes or other reductases present in mitochondria and cytosol of metabolically active cells.
The fluorescence emission wavelength (λmax=590nm) is proportional to the cellular metabolic activity over a wide concentration range, allowing for quantitative measurement of cell viability, and is thus a reliable indicator of cell health or death. The conversion of Resazurin into Resorufin also results in an easily distinguishable color change that may be measured by absorbance, albeit with some loss of sensitivity. Hence, the assay may be carried out with either a standard spectrofluorometer or a spectrophotometric microtiter well plate reader.
As Resazurin is nontoxic and the assay does not require cell lysis, after measurement, the solution can be removed and replaced with other media and cells can be cultured further for follow-up assays. Moreover, the Xpert Blue Cell Viability Assay may be carried out simultaneously with other assays, such as the determination of caspase activity, enabling obtaining more information about mechanisms that lead to cytotoxicity. Resazurin can be used for measuring cell viability and proliferation with a wide range of organisms including animal cell lines, bacteria, fungi and plants.