Fig. 4. Concentration-dependent changes in the cell viability of HeLa cells treated with MeO-BOD using a typical MTT assay (a) in the dark and (b) under light irradiation. Cells were irradiated with 560 nm light (0.1 W cm⁻², 5 and 10 min). (c) Fluorescence images of calcein AM/PI-stained HeLa cells after preincubation with MeO-BOD (0.5 and 1.0 μM) for 1 h and irradiation with 560 nm light (0.1 W cm⁻², 10 min). Scale bar: 40 μm.