MTT Assay for Cell Viability

After the cells were treated by the procedures described in Section Cell Experiment, 20 μL MTT solution (5 g/L) was added into each well and incubated for 4 h. Then, the medium was discarded, and 150 μL of DMSO was added to each well. Absorbance was measured at 490 nm (Varioskan LUX multifunctional enzyme labeling instrument, Thermo Fisher Scientific, Inc., Waltham, MA, USA) after shaking and in the dark for 20 min. The cell survival rate was calculated as follows: cell survival rate (%) = (OD value in sample group/OD value in normal group) × 100% (13).