4.4. MTT Cell Viability Assay

Cell viability 24 h after irradiation or after removal of the treatments was determined using the MTT assay. MTT solution (100 μg/mL) was added to cell cultures and incubated for 3 h at 37°C. The resulting formazan precipitate was dissolved in dimethylsulfoxide (Panreac, Barcelona, Spain) and absorbance was measured at 542 nm using a plate reader (SpectraFluor, Tecan, Zürich, Switzerland). Data were normalized with respect to non-irradiated control values.