Fig. 10

Intracellular detection of oxidative stress by flow cytometry using the DCFH-DA assay. a Histograms of the fluorescence intensities of the DCF dye in Caco-2 monocultured cells of the untreated control (UC) and the positive control (PC; 5 mM H₂O₂). The cells were treated with the probe DCFH-DA for 30 min. b Relative DCF fluorescence intensity in Caco-2 monocultured (white bars) and Caco-2/HT29-MTX cocultured cells (black bars) after 24 h of treatment with digested ZnO NP (< 50 nm and < 100 nm) and ZnCl₂ (614 µM). SC: solvent control (10% intestinal juice). Data are normalized to the untreated control (= 100%; dashed line) and expressed as mean + SD; n = 3. Significant differences compared to the untreated control (*P ≤ 0.05; ***P ≤ 0.001) and to SC (^#P ≤ 0.05; ^###P ≤ 0.001) were obtained by using the unpaired t test