Time-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.
Li et al. Nanoscale Research Letters 2013 8:96 doi:10.1186/1556-276X-8-96