Effects of differently shaped TiO 2 NPs (nanospheres, nanorods and nanowires) on the in vitro model (Caco-2/HT29) of the intestinal barrier.

BACKGROUND: The biological effects of nanoparticles depend on several characteristics such as size and shape that must be taken into account in any type of assessment. The increased use of titanium dioxide nanoparticles (TiO2 NPs) for industrial applications, and specifically as a food additive, demands a deep assessment of their potential risk for humans, including their abilities to cross biological barriers.

METHODS: We have investigated the interaction of three differently shaped TiO2 NPs (nanospheres, nanorods and nanowires) in an in vitro model of the intestinal barrier, where the coculture of Caco-2/HT29 cells confers inherent intestinal epithelium characteristics to the model (i.e. mucus secretion, brush border, tight junctions, etc.).

RESULTS: Adverse effects in the intestinal epithelium were detected by studying the barrier's integrity (TEER), permeability (LY) and changes in the gene expression of selected specific markers. Using Laser Scanning Confocal Microscopy, we detected a different behaviour in the bio-adhesion and biodistribution of each of the TiO2 NPs. Moreover, we were able to specifically localize each type of TiO2 NPs inside the cells. Interestingly, general DNA damage, but not oxidative DNA damage effects, were detected by using the FPG version of the comet assay.

CONCLUSIONS: Results indicate different interactions and cellular responses related to differently shaped TiO2 NPs, nanowires showing the most harmful effects.