*2.3. Cell Viability Analysis*

Cell viability was assessed using a modified 3-[4,5-dimethylthiazol-2]-2,5 diphenyltetrazolium bromide (MTT) assay (Sigma, St. Louis, MO, USA). Cells were seeded in 24-well dishes at a seeding density of 2 <sup>×</sup> 105 cells/well. After treatment, 300 <sup>μ</sup>L of the MTT solution (5 mg/mL) was added to each well and incubated at 37 ◦C for 3 h. After removing the culture medium, 250 μL of dimethyl sulfoxide (DMSO) was added to each well to dissolve the formazan, and then 200 μL of the solution was moved to a 96-well dish. The optical density was measured at 570 nm using a microplate reader. The absorbance of the control group was considered to have 100% cell viability.
