Fig. 3.

Viability assay (WST-8) of Caco-2 (a) and A549 (b) cells after 24 h, 48 h, 72 h, and 96 h of exposure to two doses (15 μg/ml and 45 μg/ml) of TiO₂NPs and SiO₂NPs. Viability of NP-treated cells was normalized to non-treated control cells. As positive control (P), cells were incubated with 5% DMSO (data not shown). Data reported as mean ± SD from three independent experiments are considered statistically significant compared with control (n = 8) for p value < 0.05 (< 0.05*, < 0.01**, and < 0.005***)