Fig. 1

a Cellular uptake of Sk-Br-3 cells incubated for 4 h with a series of Ce6 concentrations in the absence of fetal calf serum (FCS) and in the presence of 10% FCS. b Cellular uptake of Sk-Br-3 cells incubated for 4 h with a series of 5-ALA concentrations in the absence of FCS and in the presence of 10% FCS. c Cellular uptake of U87 cells incubated with a series of Ce6 concentrations for 1–24 h in the presence of 2% FCS. d Cellular uptake of U87 cells incubated with a series of 5-ALA concentrations for 1 and 8 h in the presence of 2% FCS. e Ce6 cellular accumulation in Sk-Br3, MCF-7, U87 and HF-5 cells after 4 h incubation with either 5 or 10 µM Ce6 in the presence of 2% FCS. f 5-ALA-PPIX cellular accumulation in Sk-Br3, MCF-7, U87 and HF-5 cells after 4 h incubation with either 0.3 or 1.2 mM 5-ALA in the presence of 2% FCS. g Representative fluorescence image of Sk-Br-3 incubated for 4 h with 10 µM Ce6 supplied in 2% FCS. h Representative fluorescence image of Sk-Br-3 cells incubated for 4 h with 1.2 mM 5-ALA supplied in 2% FCS