Figure 3From: Comparison of the killing effects between nitrogen-doped and pure TiO2 on HeLa cells with visible light irradiationTime-dependent changes of the intracellular Ca2+levels after the PDT. The averaged fluorescence intensity of control cells (white triangle) was set as 100%. TiO2 (white square)- or N-TiO2 (black circle)-treated cells (100 μg/ml) were incubated under light-free conditions for 2 h and illuminated by the visible light for 5 min.Back to article page