Fig. 6. (a) Time dependent fluorescence (λex = 504 nm, λem = 525 nm) of SOSG (1 μM) in an aqueous solution (with 5% DMSO and 1% MeOH v/v) containing Pt-Fe (50 μM) upon irradiation at 463 nm. The same solutions in the dark and SOSG alone upon irradiation were investigated for comparison; (b) relative fluorescence intensity of A549 cells treated with Pt-Fe (2 h or 1 h in the dark and 1 h irradiation, 465 nm) then probed with DCFH-DA (20 μM, λex = 490 nm, λem = 510–570 nm). H2O2 (5 mM) was used as a positive control. The statistical significance between dark and irradiated samples were evaluated by a two-tail t-test with unequal variances. *p < 0.05, **p < 0.01, ***p < 0.005; (c) confocal fluorescence microscopy images of ROS generation of A549 cells treated with Pt-Fe (IC50 concentration, 1 h in dark and 1 h irradiation, 465 nm) then probed by DCFH-DA (20 μM, λex = 488 nm, λem = 493–580 nm) in the absence and presence of antioxidant N-acetyl-l-cysteine (NAC, 10 mM). A549 cells irradiated without Pt-Fe were used as a negative control. Scale bar = 50 μm.
