alamarBlue™ HS Cell Viability Reagent (Invitrogen™)

alamarBlue HS Cell Viability Reagent is a ready-to-use resazurin-based solution that functions as a cell health indicator by using the reducing power of living cells to quantitatively measure viability. Upon entering living cells, resazurin is reduced to resorufin, a compound that is red in color and highly fluorescent. High background fluorescence caused by various contaminants reduces the performance of resazurin-based reagents. To improve the performance, an innovative purification process was developed that removes these contaminants. This highly purified, non-toxic resazurin was used in the standard alamarBlue formulation, creating the multiple-component alamarBlue HS Cell Viability Reagent. Changes in viability can be easily detected using either an absorbance- or fluorescence-based plate reader. The alamarBlue HS Cell Viability Reagent has broad applicability and can be used with various human and animal cell lines, bacteria, plant, and fungi.

alamarBlue HS Cell Viability Reagent features include:
• Removal of contaminants from resazurin—displays a >50% reduction in background fluorescence
• Signal-to-background ratio increased by >100%—results in large assay signal window
• Highly sensitive reagent with a linear response—detects as few as 20 cells per well
• Convenient add-and-read format—no mixing, no washing, no cell lysis, and compatible with either fluorescence- or absorbance-based instrumentation
• Measures viability from many diverse cell types—including mammalian cells, bacteria, plant, and fungi

Measuring changes in cell viability is a fundamental method for assessing cell health, determining genotoxicity, and evaluating anti-cancer drugs. Cell health can be monitored by detecting changes in several key indicators, including changes to plasma membrane integrity, DNA synthesis, DNA content, enzyme activity, presence of ATP, and cellular reducing environment.

Monitoring changes to the cellular reducing environment or metabolic activity by using resazurin-based reagents is a well-established and reliable indicator of cell viability or death. Upon entering living cells, the cellular reducing environment reduces resazurin to resorufin, a compound that is red in color and highly fluorescent. Viable cells continuously convert resazurin to resorufin, increasing the overall fluorescence of the medium surrounding the cells. Additionally, the conversion of resazurin to resorufin results in a pronounced color change, thus cell viability can also be detected using absorbance-based plate readers.

As a consequence of the synthesis and manufacturing processes, all resazurin-based reagents contain a detectable amount of resorufin contamination. The amount of contamination can vary greatly between sources of the material and manufacturing conditions, contributing to differences in detectable background fluorescence. More importantly, the contaminating resorufin reduces the signal to background ratio and dynamic range of the assay. An innovative process was developed that removes the contaminating resorufin, resulting in the highly pure resazurin used in alamarBlue HS Cell Viability Reagent.

alamarBlue HS Cell Viability Reagent is a complete add-and-read, non-toxic reagent that does not require cell lysis. The highly purified resazurin used for alamarBlue HS reagent results in a >50% decrease in background fluorescence and a >100% increase in the signal-to-background ratio. Since no lysis is required, the diluted alamarBlue HS solution can be removed and replaced with complete growth medium for further culturing of the cells. Similar to alamarBlue reagent, alamarBlue HS reagent displays an extended viability detection time window for a wide variety of organisms and thus can be used with various human and animal cell lines, bacteria, plant, and fungi, resulting in quantitative measurement of cell viability and proliferation.