Figure 3

Viability of Caco-2 cells exposed for 4 h, 24 h or 72 h toTiO ₂ STNPs. Caco-2 cells were grown in a 96-well plate and differentiated for 21 days. The cells were then exposed for 4 h, 24 h or 72 h at TiO₂ STNPs concentrations ranging from 10 to 100 μl/mL. A) Cell viability was determined by intracellular ATP content ( CellTiter-Glo luminescent cell viability Assay, Promega). B) Cell viability was determined by mitochondrial enzyme activity via XTT reagent (In Vitro toxicology assay kit XTT based, Sigma-Aldrich).