(a) Dark toxicity of photosensitizers. T98G cells were incubated in the dark during 18 hours with different concentrations of TAZnPc (white bars) or ZnPc (black bars) dissolved in DMEM supplemented with 4% of FBS plus antibiotics. Then the cells were washed and viability assessed using alamarBlue as described under Materials and Methods. Results are presented as mean percentage of viability with respect to the control (cells without Pc) ± SEM of three independent experiments performed in triplicate. (b) Cellular uptake was measured by two methods as described under Materials and Methods. Values are presented as pmoles/106 cells ± SEM of a representative experiment. Flow cytometer results are presented in the inset graph. The results are the mean ± SD of the fluorescence intensity change compared to the control of a representative experiment out of two done in triplicate.