Not Available

Funder

Organizational Unit

Publications

Analysis of the In Vitro Toxicity of Nanocelluloses in Human Lung Cells as Compared to Multi-Walled Carbon Nanotubes

Publication . Pinto, Fátima; Lourenço, Ana Filipa; Pedrosa, Jorge F.S.; Gonçalves, Lídia; Ventura, Célia; Vital, Nádia; Bettencourt, Ana; Fernandes, Susete N.; da Rosa, Rafaela R.; Godinho, Maria Helena; Louro, Henriqueta; Ferreira, Paulo J.T.; Silva, Maria João

Cellulose micro/nanomaterials (CMNM), comprising cellulose microfibrils (CMF), nanofibrils (CNF), and nanocrystals (CNC), are being recognized as promising bio-nanomaterials due to their natural and renewable source, attractive properties, and potential for applications with industrial and economical value. Thus, it is crucial to investigate their potential toxicity before starting their production at a larger scale. The present study aimed at evaluating the cell internalization and in vitro cytotoxicity and genotoxicity of CMNM as compared to two multi-walled carbon nanotubes (MWCNT), NM-401 and NM-402, in A549 cells. The exposure to all studied NM, with the exception of CNC, resulted in evident cellular uptake, as analyzed by transmission electron microscopy. However, none of the CMNM induced cytotoxic effects, in contrast to the cytotoxicity observed for the MWCNT. Furthermore, no genotoxicity was observed for CNF, CNC, and NM-402 (cytokinesis-block micronucleus assay), while CMF and NM-401 were able to significantly raise micronucleus frequency. Only NM-402 was able to induce ROS formation, although it did not induce micronuclei. Thus, it is unlikely that the observed CMF and NM-401 genotoxicity is mediated by oxidative DNA damage. More studies targeting other genotoxicity endpoints and cellular and molecular events are underway to allow for a more comprehensive safety assessment of these nanocelluloses.

2022-04-22Journal article

Open access

Oral Exposure to Titanium dioxide nanoparticles: a Systematic Literature Review as a tool to develop Adverse Outcome Pathway landscapes and supporting in vitro assays

Publication . Rolo, Dora; Silva, Maria João; Louro, Henriqueta

Despite being considered key enabling technologies, the exponential use of nanoparticles in food technology leads to concerns about adverse health outcomes upon ingestion. The use of Titanium dioxide nanoparticles (TiO2-NPs) as a food additive was considered no longer safe by the European Food Safety Authority (EFSA) in 2022, and the European Commission announced the decision to ban its use. Nevertheless, other products containing TiO2-NPs, such as pharmaceuticals, personal hygiene, or cosmetics, that are not covered in the food regulation, may lead to ingestion of TiO2-NPs. In this regard, further research is needed. A valuable tool is the establishment of Adverse Outcome Pathways (AOPs) landscapes, which contributes to support risk assessment and may drive policy decisions. AOPs describes a sequence of causally linked events at different levels of biological organization leading to adverse health effects. Our main goal was to further understand the molecular and cellular mechanisms, triggered after the ingestion of TiO2-NPs. A systematic literature review was performed, integrating information produced on this topic and provide data for a standardized assessment of the evidence. AOP landscapes were proposed in order to identify mechanisms that mediate adverse outcomes, and additional in vitro assays were performed. Our in vitro findings suggest that part of the ingested TiO2-NPs can be transcytosed through colonic epithelia without disrupting intestinal barrier integrity. These results are consistent with our AOPs proposal where colorectal cancer, liver injury, reproductive toxicity, cardiac and kidney damage, as well as hematological effects stand out as possible adverse outcomes. Based on a mechanistic reasoning, this study contributes to increase the understanding of ingested TiO2-NPs kinetics, their bioavailabity to induce systemic effects crossing the intestinal barrier and potential fate in Humans. Overall, the findings further support a limitation of the use of TiO2-NPs in food, as announced by EFSA.

2022-11-16Lecture

Restricted access

Cellular, Molecular and Genotoxic Effects of Digested Titanium Dioxide Nanomaterials

Publication . Louro, Henriqueta

About Cellular, Molecular and Genotoxic Effects of Digested Titanium Dioxide Nanomaterials.

2022-09-16Lecture

Restricted access

Cellular, Molecular and Genotoxic Effects of Digested Titanium Dioxide Nanomaterials

Publication . Rolo, Dora; Pereira, Joana F.S; Vieira, Adriana; Roque, Rossana; Gramacho, Ana Catarina; Vital, Nádia; Matos, Paulo; Gonçalves, Lídia; Bettencourt, Ana F.; Silva, Mafalda A.; Martins, Carla; Assunção, Ricardo; Alvito, Paula; Jordan, Peter; Silva, Maria João; Louro, Henriqueta

Human exposure to titanium dioxide nanomaterials(TiO2NMs) occurs particularly by ingestion, due to food/food contact materials and consumer products. However, the possibility of adverse effects in gastrointestinal tract is unclear. Aiming to study the impact of digestion on the NMs’ properties and their cellular/molecular effects, two human intestinal cell lines were used, Caco-2 and HT29-MTX-E12. After exposure to TiO2NMs(NM-102, NM-103, NM-105), undigested or subjected to standardized static in vitro digestion method (mimicking human digestion), the cells were analyzed for toxicity, genotoxicity, reactive oxygen species, NM uptake and intestinal translocation. We showed that in vitro digestion of TiO2NMs may increase their toxicity and DNA-damaging effect, depending on the NM, more relevant for the rutile/anatase NM-105, possibly due to its smaller hydrodynamic size in the cellular medium. Effects on chromosomal integrity were seen in HT29-MTX-E12 cells, for all tested TiO2NMs, especially after digestion. Internalization into early endosomes was confirmed for NM-103 and NM-105, before and after digestion, in monolayers of both cell lines, and at the apical membrane of polarized Caco-2 cells. The internalized NMs accumulated in late endosomes/multivesicular bodies, partially transversing the basolateral membrane of polarized Caco-2 cells without changing transepithelial electrical resistance or epithelial marker abundance. These results suggest that part of the TiO2NMs can be transcytosed through colonic epithelia without disrupting intestinal barrier integrity. Overall, the biological outcomes from TiO2NMs interaction with intestinal cells were more pronounced after digestion, highlighting its relevance in the hazard assessment of ingested NMs.

2022-08-31Conference object

Restricted access

Investigation of the genotoxicity of digested titanium dioxide nanomaterials in human intestinal cells

Publication . Vieira, Adriana; Vital, Nádia; Rolo, Dora; Roque, Rossana; Gonçalves, Lídia M.; Bettencourt, Ana; Silva, Maria João; Louro, Henriqueta

The widespread use of titanium dioxide nanomaterials (TiO2 NMs) in food and consumer products such as toothpaste or food contact materials, suggests the relevance of human oral exposure to these nanomaterials (NMs) and raises the possibility of adverse effects in the gastrointestinal tract (GIT). We previously showed that the in vitro digestion of TiO2 NMs may increase their toxicity in intestinal cells. In this work, we analyzed the genotoxicity and the intracellular reactive oxygen species induction by physiologically relevant concentrations of three different TiO2 NMs (NM-102, NM-103 and NM-105) in Caco-2 and HT29-MTX-E12 intestinal cells, while considering the potential influence of the digestion process in the NMs' physiochemical characteristics. The results evidenced a DNA-damaging effect dependent on the NM, more relevant for the rutile/anatase NM-105, possibly due to its lower hydrodynamic size in the cells medium. In addition, the results of the micronucleus assay suggest effects on chromosomal integrity, an indicator of cancer risk, in the HT29-MTX-E12 cells, for all the tested TiO2 NMs, especially after the in vitro digestion. This work supports the evidence for concerns on the use of TiO2 NMs as a food additive, recently reported by EFSA, and for their use in applications in consumer products that may drive human exposure through ingestion.

2022-03Journal article

Open access