Alamar Blue

The dye incorporates an oxidation-reduction (REDOX) indicator that both fluoresces and changes color in response to the chemical reduction of growth medium due to cell growth. The Alamar Blue (resazurin) dye in its oxidized form is blue in color and non-fluorescent. In the Alamar Blue assay the growing cells cause a chemical reduction of the Alamar Blue dye from non-fluorescent blue to red fluorescent. The continued growth of viable cells maintain a reducing environment (fluorescent, red) and inhibition of growth maintains an oxidized environment (non-fluorescent, blue), which can be detected using a fluorescence or absorbance detector.