Fig. 4. (a) ROS generation in cells incubated with CaO₂/B1 lipo and CaO₂/B1/NH₄HCO₃ lipo (80 μg mL^–1) under 21% and 5% oxygen levels and then exposed to irradiation; (b) calcein-AM/PI staining of cells incubated with CaO₂/B1 lipo and CaO₂/B1/NH₄HCO₃ lipo (80 μg mL^–1) under a 5% oxygen level and then exposed to irradiation; MTT assays of cells incubated with CaO₂/B1 lipo and CaO₂/B1/NH₄HCO₃ lipo (80 μg mL^–1) under 21% (c) and 5% (d) oxygen levels and then exposed to irradiation; flow cytometry results of cells incubated with CaO₂/B1 lipo and CaO₂/B1/NH₄HCO₃ lipo (80 μg mL^–1) under 21% (e) and 5% (f) oxygen levels and then treated with Annexin V-FITC/PI under irradiation. The excitation wavelength of irradiation is 730 nm. The power density is 500 mW cm^–2. The irradiation time is 5 min.