Fig. 7
Cell membrane integrity assay 24 h after the third SW treatment in A HT-29 and B Colo 320DM cells incubated with 10 µg/ml of Fe:ZnO NCs in 96-well plates. After 24 h of NCs incubation, cells were exposed to 250 shots of SW (0.12 mJ/mm2, 4 shots/s) for three times (a treatment every 4 h), while control cells were not exposed, or were treated with Fe:ZnO NCs or 3SW only. 24 h after the third treatment, the cell culture medium was replaced with 1.5 µM propidium iodine (as indicator of membrane integrity) in PBS phosphate saline buffer. Cells were then observed under a wide-field fluorescence-inverted microscope (Eclipse Ti-E, Nikon) with 20X magnification objective lens. Scale bar is 200 µm