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Analysis Of The Cytotoxicity And Genotoxicity of Digested Titanium Dioxide Nanomaterials (TiO2) In Intestinal Cells

Publication . Louro, Henriqueta; Vieira, Adriana; Gramacho, Ana Catarina; Rolo, Dora; Vital, Nádia; Martins, Carla; Assunção, Ricardo; Alvito, Paula; Gonçalves, Lídia; Bettencourt, Ana Francisca; Silva, Maria João

Titanium dioxide nanomaterials (TiO2) have been frequently applied as food additives, in pharmaceuticals and in personal care products, such as toothpastes. Despite some regulators like EFSA concluded that the absorption of orally administered TiO2 is low, and that the use of TiO2 as a food additive does not raise a genotoxic concern, the presence of TiO2 in human organs was recently reported. This exposure may lead to adverse outcomes and has been poorly investigated. Furthermore, many of the biological effects of TiO2 described in the literature often overlook adequate physicochemical properties and their modification due to NMs interaction with the surrounding physiological matrices happening, e.g, during digestion. This work aimed to investigate in intestinal cells, the cyto- and genotoxic effects of TiO2 after the simulation of the human digestive process using the standardized INFOGEST in vitro digestion method, to better understand their potential negative impacts on the gastrointestinal tract. The TiO2 were characterized before and after digestion using DLS, zeta potential and TEM-EDS. The digestion product was used for cytotoxicity (MTT) and genotoxicity (comet, micronucleus) assays in two types of intestinal cells (Caco-2 and mucus secreting HT29-MTX cells). The results of the cytotoxicity and genotoxicity assays are discussed in view of the TiO2 secondary characteristics, to further understand the potential adverse intestinal outcomes in light of the transformation they suffer during digestion.

2020-09-12Conference object

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Validation of Caco-2/HT29-MTX model to assess the potential risk of ingested titanium dioxide nanoparticles

Publication . Rolo, Dora; Pereira, Joana F.S.; Matos, Paulo; Vieira, Adriana; Vital, Nádia; Jordan, Peter; Silva, Maria João; Louro, Henriqueta

The increased use of titanium dioxide nanoparticles (TiO2NPs) as a food additive demands a deep assessment of their potential risk for human health, including their abilities to cross biological barriers. In vitro models of the intestinal barrier are being increasingly used to evaluate NPs exposure risk. Most of these studies have focused on standard monoculture models of Caco-2 monolayers. However, they exhibit several limitations such as the lack of mucus layer and a low paracellular permeability. We aim to study TiO2NPs with an in vitro model of intestinal barrier using co-culture of two types of cells: absorptive Caco-2 and mucus-secreting HT29-MTX. This co-culture confers more physiological intestinal epithelium-like properties to the model, such as mucus secretion and tight junction formation, allowing a more adequate investigation of the cellular effects elicited by NPs. Due to the multiple variables and parameters playing a part when the model's complexity is increased, we characterized the robustness of this model by evaluating cell differentiation by confocal microscopy and Western blot while monitoring epithelial barrier formation, through measurement of both transepithelial resistance (TEER)and paracellular permeability (Lucifer yellow). An optimized model of the intestinal barrier will be used to better understand the uptake, adhesion and localization of TiO2NPs, both directly and after the simulation of the human digestive process using the harmonized in vitro digestion protocol. Preliminary data shows that these complex models can add valuable information to study the potential negative impacts and genotoxicity of TiO2NPs on human health.

2020-09-12Conference object

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Toxicological Assessment of Cellulose Nanomaterials: Oral Exposure

Publication . Vital, Nádia; Ventura, Célia; Kranendonk, Michel; Silva, Maria João; Louro, Henriqueta

Cellulose nanomaterials (CNMs) have emerged recently as an important group of sustainable bio-based nanomaterials (NMs) with potential applications in multiple sectors, including the food, food packaging, and biomedical fields. The widening of these applications leads to increased human oral exposure to these NMs and, potentially, to adverse health outcomes. Presently, the potential hazards regarding oral exposure to CNMs are insufficiently characterised. There is a need to understand and manage the potential adverse effects that might result from the ingestion of CNMs before products using CNMs reach commercialisation. This work reviews the potential applications of CNMs in the food and biomedical sectors along with the existing toxicological in vitro and in vivo studies, while also identifying current knowledge gaps. Relevant considerations when performing toxicological studies following oral exposure to CNMs are highlighted. An increasing number of studies have been published in the last years, overall showing that ingested CNMs are not toxic to the gastrointestinal tract (GIT), suggestive of the biocompatibility of the majority of the tested CNMs. However, in vitro and in vivo genotoxicity studies, as well as long-term carcinogenic or reproductive toxicity studies, are not yet available. These studies are needed to support a wider use of CNMs in applications that can lead to human oral ingestion, thereby promoting a safe and sustainable-by-design approach. View Full-Text

2022-09-27Journal article

Open access