Biological effect of food additive titanium dioxide nanoparticles on intestine: an in vitro study

Titanium dioxide nanoparticles (TiO 2 NPs) are widely found in food‐related consumer products. Understanding the effect of TiO 2 NPs on the intestinal barrier and absorption is essential and vital for the safety assessment of orally administrated TiO 2 NPs. In this study, the cytotoxicity and translocation of two native TiO 2 NPs, and these two TiO 2 NPs pretreated with the digestion simulation fluid or bovine serum albumin were investigated in undifferentiated Caco‐2 cells, differentiated Caco‐2 cells and Caco‐2 monolayer. TiO 2 NPs with a concentration less than 200 µg ml –1 did not induce any toxicity in differentiated cells and Caco‐2 monolayer after 24 h exposure. However, TiO 2 NPs pretreated with digestion simulation fluids at 200 µg ml –1 inhibited the growth of undifferentiated Caco‐2 cells. Undifferentiated Caco‐2 cells swallowed native TiO 2 NPs easily, but not pretreated NPs, implying the protein coating on NPs impeded the cellular uptake. Compared with undifferentiated cells, differentiated ones possessed much lower uptake ability of these TiO 2 NPs. Similarly, the traverse of TiO 2 NPs through the Caco‐2 monolayer was also negligible. Therefore, we infer the possibility of TiO 2 NPs traversing through the intestine of animal or human after oral intake is quite low. This study provides valuable information for the risk assessment of TiO 2 NPs in food. Copyright © 2015 John Wiley & Sons, Ltd.