Description
The CellTiter-Blue® Cell Viability Assay provides a homogeneous, fl uorometric method for estimating the number
of viable cells present in multiwell plates. It uses the indicator dye resazurin to measure the metabolic capacity of
cells—an indicator of cell viability. Viable cells retain the ability to reduce resazurin into resorufi n, which is highly
fl uorescent (Figure 1). Nonviable cells rapidly lose metabolic capacity, do not reduce the indicator dye, and thus
do not generate a fl uorescent signal.
The CellTiter-Blue® Reagent is a buff ered solution containing highly purifi ed resazurin. The ingredients have been
optimized for use as a cell viability assay. The spectral properties of CellTiter-Blue® Reagent change upon
reduction of resazurin to resorufi n (Figure 2). Resazurin is dark blue in color and has little intrinsic fl uorescence
until it is reduced to resorufi n, which is pink and highly fl uorescent (579Ex/584Em).
The visible light absorbance properties of CellTiter-Blue® Reagent undergo a “blue shift” upon reduction of
resazurin to resorufi n. The absorbance maximum of resazurin is 605nm and that of resorufi n is 573nm. Either
fl uorescence or absorbance may be used to record results; however, fl uorescence is the preferred method because
it is more sensitive and involves fewer data calculations.