(A) MDA-MB-231 cells were incubated with different concentrations of PTH1, PTH2 and PTH3 during 72 h. After treatment, cells were submitted to MTT assay to quantify the cell death. (B) MDA-MB-231 cells were incubated with or without PTH1, PTH2 and PTH3 during the allocated 24 h. The cells were incubated with Hoechst 15 min. They were imaged at 450 nm for polythiophenes and 760 nm for Hoechst using a confocal miscroscope. (C) MDA-MB-231 cells were incubated with PTH1, PTH2 and PTH3 during the allocated 24 h. The cells were irradiated for 5 min using a standard fluorescent microscope with a mercury lamp at 450 nm, magnification x4. Two days after irradiation, cells were submitted to MTT assay to quantify the cell death. * Statistical significance (p < 0.05) of the irradiated condition versus the non-irradiated condition using Student’s t-test.