Nano-bio interactions of titanium dioxide nanomaterials in the intestinal moiety after simulated digestion in vitro

The exponential development of nanomaterials (NMs) contrasts with insufficient risk assessment for human health and the environment, leading to concerns for public health. Their potential to improve many products and processes, namely in agriculture, food and feed industry, has led to increased use of NMs, such as titanium dioxide nanomaterials (TiO2). In fact, oral exposure to TiO2 may occur either directly, through the consumption of products/pharmaceuticals containing NMs, or indirectly, through the ingestion of food/water contaminated due to environmental accumulation. Therefore, the gastrointestinal tract (GIT) appears to be a probable route of exposure to NMs and may lead to systemic exposure if the body barriers are surpassed. Since NMs primary physicochemical properties may define nano-bio interactions1, NMs with the same chemistry but with different shape, diameter, length, surface charge or functionalization may lead to different toxicities. Conversely, since the GIT is chemically and physically complex, ingested NMs will pass through different environments prior to their intestinal uptake, affecting their physicochemical properties, so that these secondary physicochemical properties should be considered while evaluating their safety in the food chain. The aim of this work was to investigate the nano-bio interactions of three TiO2 (NM-102, NM-103, NM-105, from Joint Research Centre, Ispra) in the context of intestinal tract and digestion processes. As alternative to animal testing, an in vitro harmonized digestion method2 was used for simulating the human digestion of NMs and their characteristics were studied in acellular and intestinal (Caco-2) cells context. The NMs were characterized using dynamic light scattering (DLS, for size distribution), electrophoretic light scattering (zeta potential), transmission electron microscopy (TEM) for morphological characterization and X-ray energy dispersive spectrometry (EDS) for elemental chemical analysis. TiO2 samples were labelled directly with a fluorescent probe and used for uptake studies with confocal microscopy (CM). In parallel, a co-culture model of Caco-2 with mucous-secreting HT29-MTX was initiated and exposed to TiO2 to ascertain epithelial barrier translocation. The results did not show major differences in the NMs’ pH, osmolality, charge signal or mean size, except for NM-103. TEM and TEM –EDS analysis showed that it is possible to identify primary particles after digestion process and preliminary CM results suggest that some of the tested TiO2 nanomaterials can be uptake by the cells, suggestive of potential subcellular effects that warrant further investigation. References [1] H. Louro, A. Saruga, J. Santos, M. Pinhão, M.J. Silva, Toxicol. In Vitro. 56 (2019)172–183. [2] A. Brodkorb, L.Egger, M. Alminger, P. Alvito et al. Nat Protoc. 2019 Apr;14(4):991-1014.

Keywords

Environmental Genotoxicity Ingested Nanomaterials Nanotoxicology Food Safety Genotoxicidade Ambiental Segurança Alimentar

URI

http://hdl.handle.net/10400.18/7434

Citation

Henriqueta Louro, Dora Rolo, Ana C. Gramacho, Joana Pereira, Paulo Matos, Peter Jordan, Carla Martins, Ricardo Assunção, Paula Alvito, Lídia Gonçalves, Ana F. Bettencourt, Maria João Silva.2020. Nano-bio interactions of titanium dioxide nanomaterials in the intestinal moiety after simulated digestion in vitro. IVth International Caparica Symposium on Nanoparticles, Nanomaterials and Applications 2020 (ISN2A), 20 January 2020, Caparica, Portugal. Oral communication.