Fig. 4

Impact of silica NFs on intestinal models. A Undifferentiated Caco-2 cells were cultured in a 96 well plates for 24 h and exposed to various concentrations of silica and CuO NM (from 0.98 to 125 µg/mL) for 24 h followed by the assessment of viability using Alamar blue assay. B Impact on barrier integrity of triple culture model measured daily for 5 days during exposure of NFs (33.6 µg/mL) using TEER (only selected days are shown). C Undifferentiated Caco-2 IL-8 production after 24 h of exposure to 48 µg/mL of NFs and D IL-8 production assessed on the fifth day apical supernatant of 3D model using Enzyme-linked immunosorbent assays (ELISA) exposed to 33.6 µg/mL of NFs. E, F, G and H BF pairwise similarity assessment was conducted comparing the curves of % viability, % of TEER value, undifferentiated Caco-2 cells and triple culture IL-8 production measured in pg/mL respectively, together with the concentration values and different time points (TEER measurements). Values range between 0 and 1 (similar NFs). Values close to zero indicate that the NFs are not similar. Data are shown as mean ± standard deviation. * p ≤ 0.05 vs untreated. Triton X100 (0.01%) was used as positive control for viability and TEER experiments, whereas TNF-α (2 µg/mL) was used as positive control for cytokine secretion