Ingested nanomaterials: impact of digestion process in the physicochemical characteristics and biological consequences in intestinal cells

Nanomaterials(NMs) provide a basis for key enabling technologies, in view of their potential to improve many products and processes, namely in food and feed industry. That is the case of titanium dioxide NMs(TiO2 NMs), presenting beneficial properties for a broad range of innovative applications such as food additives, toothpaste, pharmaceuticals, food products, etc., that may drive ingestion. The oral exposure can occur directly, by consumption of products/pharmaceuticals or foods containing NMs, or indirectly, through the ingestion of foods contaminated with NMs released from food-contact materials or environmental sources. As such, the gastrointestinal tract is the first site of contact of the ingested NMs, allowing a systemic exposure if the intestinal barriers is surpassed. This work aimed to investigate how the digestion process affects the physicochemical properties of three different TiO2 NMs(NM-102, NM-103 and NM-105) and their toxic effects on intestinal cells. After undergoing digestion through the standardized static INFOGEST 2.0 in vitro digestion method, the cytotoxicity of the TiO2 NMs was determined in Caco-2 and HT29-MTX-E12 intestinal cells, using the MTT assay. Furthermore, the cytokinesis-blocked micronucleus assay was used to investigate their genotoxicity in both cell lines in order to predict their carcinogenic potential. The results showed that, for one TiO2 NM(NM-105), the digestion caused changes in the hydrodynamic size of the NM and a more pronounced toxicity in HT29-MTX-E12 intestinal cells, as compared to the undigested one. The micronucleus assay suggests effects on the chromosomal integrity in the HT29-MTXE12 cells, for all the tested TiO2 NM especially after the in vitro digestion. Overall, we conclude that including the digestion prior to the in vitro bioassays for the safety evaluation of ingested NMs, allows integrating the physiological modifications that the NMs suffer in the organism, contributing to an improved hazard assessment of ingested NMs.

Keywords

Environmental Genotoxicity Ingested Nanomaterials Nanotoxicology Genotoxicity Nanomaterials Genotoxicidade Ambiental Segurança Alimentar Composição dos Alimentos Avaliação do Risco