the culture medium and MTT formazan crystals from each well using 100 µL of acidified isopropanol (0.04 N HCl in 70% isopropanol). Gently shake the plate for 1 min and aspirate the contents completely using a multichannel pipettor. 4. Transfer the plate to a new 96-well plate containing 100 µL of 0.1 N NaOH per well and gently shake for 15 min on an orbital shaker platform set at low speed (<100 rpm). 5. Aspirate the contents of each well completely and transfer 50 µL of the solution from each well to a new 96 well plates. 6. Read the absorbance at 550nm. 7. The amount of formazan produced is directly proportional to the number of living cells present in the culture and can be used to calculate cell viability. This assay has several advantages over other methods of measuring cell viability including its simplicity, speed, and sensitivity. Additionally, the MTT assay can be easily adapted for high-throughput screening applications. Observation The Optical Density (OD) at 550nm will be used to calculate the percentage of viability results using the following equation: Viability % = 100 x OD550e/OD 550b Where, OD550e – Mean value of the measured optical density of the test item. OD550b – Mean value of the measured optical density of the negative control. See also Tetrazolium chloride Formazan References Further reading External links MTT assay Protocol Biochemistry detection reactions