Figure 7. Luminescence images (a) and intensity (b) of HeLa cells treated with P1 followed by incubation with NaF at different experimental conditions: (1) normal, laser power is normal, 3 h; (2) the incubation duration was increased to 4 h; (3) the P1 concentration for incubation was increased from 1.0 × 10^–2 mg/mL to 2.0 × 10^–2 mg/mL; (4) the 405 nm laser power was increased. Scale bar is 20 μm.