Cytotoxicity of cis-[Ru(bpy)2(2)2]Cl2 (4), cis-[Ru(bpy)2(3)2](BF4)2 (5) and the control compound cis-[Ru(bpy)2(MeCN)2](PF6)2 on BMM cells (A–C) and prostate cancer PC3 cells (D–F). Cells were incubated in the presence of 4, 5 or cis-[Ru(bpy)2(MeCN)2](PF6)2 (1 nM-100 μM) for 30 min, left in the dark (black) or irradiated (red) for 15 min (complex 4, and cis-[Ru(bpy)2(MeCN)2](PF6)2) or 40 min (complex 5) with a tungsten halogen lamp (250 W, λirr > 395 nm, H2O filter) and washed. For comparison, PC3 cells were exposed to increasing concentrations (10 nM – 200 nM) of know cytotoxic agent, Docetaxel (Figure S10). Cell viability was determined using the MTT assay after 24 h, and is reported relative to control with only buffer added. Error bars represent the standard deviations of triplicate wells, and data are representative of three independent experiments. ** indicates p<0.001.