Fig. 2
Impact of CuO NMs and CuSO4 on the differentiated and undifferentiated Caco-2 cell monolayer. a) Impact of CuO NMs and CuSO4 on differentiated Caco-2 cell TEER values. Following differentiation, Caco-2 cells were exposed to cell culture medium (control, 0), CuO NMs or CuSO4 at concentrations of 6.34 or 12.68 μg/cm2 Cu at the apical compartment. The TEER values were measured using epithelial volt-ohmmeter EVOM every 3 h. Data are expressed in mean TEER value ± SEM (n = 3) and * represents significant difference compared to control at P < 0.05. b) Differentiated and undifferentiated Caco-2 cell morphology following exposure to CuO NM or CuSO4. Cells were exposed to control (cell culture medium) and 6.34 μg/cm2 Cu CuO NM or CuSO4 for 24 h. The cells were fixed, stained and visualised using the light microscopy (magnification 40X, scale bar = 500 μm. c) Total nuclei count of differentiated and undifferentiated Caco-2 cells. d) Representative image of nuclei staining with DAPI (field of view: 140.80 X 105.60 μm). i) Untreated differentiated Caco-2 cell, ii) differentiated Caco-2 cell treated with 6.34 μg/cm2Cu CuO NM, iii) differentiated Caco-2 cell treated with 6.34 μg/cm2Cu CuSO4 and iv) untreated undifferentiated Caco-2 cell. For c and d, the nucleus were stained with DAPI and the images obtained with Zeiss fluorescent Microscope, Carl Zeiss Axio Scope A 1 Upright Research Microscope (magnification 40X) and the results analysed using Image J software. Scale bar = 10 μm