Mtt solution

Cells of the exponential growth phase were trypsinized, followed by seeding into 96-well plates (2000 cells/well). After adding 20 µl of 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) solution (5 mg/ml, GenView, USA) at 24, 48, 72, and 96 h, cells were incubated for another 4 h and then treated with 100 µl of DMSO solution. Cell survival was calculated by measuring optical density (OD) at 490 nm with a microplate reader (Tecan, Switzerland).

An MTT assay was performed to measure cell growth. The cells were seeded at 2,000 per well in 96-well plates and incubated at 37°C for a designed time period. For each test, 20 µl of MTT solution (5 mg/ml; Genview Tallahasses, FL, USA) was added to each of the wells, followed by incubation at 37°C for 4 h. Subsequently, 100 µl of dimethyl sulfoxide solution was added to resolve the formazan crystals overnight at 37°C. The optical density at 490 nm was measured the following day to determine the quantities of formazan formed by cleaving MTT in living cells. For each treatment, the cells were cultured for 5 days and the samples were prepared for the quantitative MTT assay once per day following plating. Three independent assays were performed, and two samples were measured at each time point.

A549 cells (2 × 10³/well) were plated and treated as described above. The MTT assay was performed daily for 5 days. Briefly, 20 µL of MTT solution (5 mg/mL; Genview, Houston, TX, USA) was added to each well and mixed well. A549 cells were then incubated at 37°C for 4 hours, after which medium containing MTT was removed and 100 µL dimethyl sulfoxide was added. The optical density at 490 nm was measured using the Infinite M2009PR plate reader (Tecan, Crailsheim, Germany).