Multiparametric in vitro genotoxicity assessment of different variants of amorphous silica nanomaterials in rat alveolar epithelial cells

The hazard posed to human health by inhaled amorphous silica nanomaterials (aSiO2 NM) remains uncertain. Herein, we assessed the cyto- and genotoxicity of aSiO2 NM variants covering different sizes (7, 15, and 40 nm) and surface modifications (unmodified, phosphonate-, amino- and trimethylsilyl-modified) on rat alveolar epithelial (RLE-6TN) cells. Cytotoxicity was evaluated at 24 h after exposure to the aSiO2 NM variants by the lactate dehydrogenase (LDH) release and WST-1 reduction assays, while genotoxicity was assessed using different endpoints: DNA damage (single- and double-strand breaks [SSB and DSB]) by the comet assay for all aSiO2 NM variants; cell cycle progression and γ-H2AX levels (DSB) by flow cytometry for those variants that presented higher cytotoxic and DNA damaging potential. The variants with higher surface area demonstrated a higher cytotoxic potential (SiO2_7, SiO2_15_Unmod, SiO2_15_Amino, and SiO2_15_Phospho). SiO2_40 was the only variant that induced significant DNA damage on RLE-6TN cells. On the other hand, all tested variants (SiO2_7, SiO2_15_Unmod, SiO2_15_Amino, and SiO2_40) significantly increased total γ-H2AX levels. At high concentrations (28 µg/cm2), a decrease in G0/G1 subpopulation was accompanied by a significant increase in S and G2/M sub-populations after exposure to all tested materials except for SiO2_40 which did not affect cell cycle progression. Based on the obtained data, the tested variants can be ranked for its genotoxic DNA damage potential as follows: SiO2_7 = SiO2_40 = SiO2_15_Unmod > SiO2_15_Amino. Our study supports the usefulness of multiparametric approaches to improve the understanding on NM mechanisms of action and hazard prediction

Unveiling the Toxicity of Fine and Nano-Sized Airborne Particles Generated from Industrial Thermal Spraying Processes in Human Alveolar Epithelial Cells

High-energy industrial processes have been associated with particle release into workplace air that can adversely affect workers' health. The present study assessed the toxicity of incidental fine (PGFP) and nanoparticles (PGNP) emitted from atmospheric plasma (APS) and high-velocity oxy-fuel (HVOF) thermal spraying. Lactate dehydrogenase (LDH) release, 2-(4-nitrophenyl)-2H-5-tetrazolio]-1,3-benzene disulfonate (WST-1) metabolisation, intracellular reactive oxygen species (ROS) levels, cell cycle changes, histone H2AX phosphorylation (γ-H2AX) and DNA damage were evaluated in human alveolar epithelial cells at 24 h after exposure. Overall, HVOF particles were the most cytotoxic to human alveolar cells, with cell viability half-maximal inhibitory concentration (IC50) values of 20.18 μg/cm2 and 1.79 μg/cm2 for PGFP and PGNP, respectively. Only the highest tested concentration of APS-PGFP caused a slight decrease in cell viability. Particle uptake, cell cycle arrest at S + G2/M and γ-H2AX augmentation were observed after exposure to all tested particles. However, higher levels of γ-H2AX were found in cells exposed to APS-derived particles (~16%), while cells exposed to HVOF particles exhibited increased levels of oxidative damage (~17% tail intensity) and ROS (~184%). Accordingly, APS and HVOF particles seem to exert their genotoxic effects by different mechanisms, highlighting that the health risks of these process-generated particles at industrial settings should not be underestimated. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.Funding text 1: transitória (Ref. DL-57/INSA-06/2018). Thanks are also due to FCT/MCTES for the financial support to EPIUnit and ITR (UIDB/04750/2020 and LA/P/0064/2020). Informed Consent Statement: Not applicable. Institutional Review Board Statement: Not applicable.; Funding text 2: Funding: This research was funded by the project CERASAFE with the support of ERA-NET SIINN (project id:16) and the Portuguese Foundation for Science and Technology (FCT; SIINN/0004/2014). This work was also supported by the project NanoBioBarriers (PTDC/MED-TOX/31162/2017), cofinanced by the Operational Program for Competitiveness and Internationalization (POCI) through European Regional Development Funds (FEDER/FNR) and FCT and the Spanish Ministry of Sci- ence and Innovation (projects PCIN-2015-173-C02-01 and CEX2018-000794-S-Severo Ochoa). M.J. Bessa (SFRH/BD/120646/2016) and F. Brandão (SFRH/BD/101060/2014) are recipients of FCT PhD scholarships under the framework of the Human Capital Operating Program (POCH) and European Union funding. The Doctoral Program in Biomedical Sciences of the ICBAS—University of Porto Int.J.Mol. Sci. 2022,of23fer, x FOR PEER REVIEWed additional funds. S. Fraga thanks FCT for funding through program DL 57/2016—Norm

In Vitro Toxicity of Industrially Relevant Engineered Nanoparticles in Human Alveolar Epithelial Cells: Air-Liquid Interface versus Submerged Cultures

Diverse industries have already incorporated within their production processes engineered nanoparticles (ENP), increasing the potential risk of worker inhalation exposure. In vitro models have been widely used to investigate ENP toxicity. Air–liquid interface (ALI) cell cultures have been emerging as a valuable alternative to submerged cultures as they are more representative of the inhalation exposure to airborne nano-sized particles. We compared the in vitro toxicity of four ENP used as raw materials in the advanced ceramics sector in human alveolar epithelial-like cells cultured under submerged or ALI conditions. Submerged cultures were exposed to ENP liquid suspensions or to aerosolised ENP at ALI. Toxicity was assessed by determining LDH release, WST-1 metabolisation and DNA damage. Overall, cells were more sensitive to ENP cytotoxic effects when cultured and exposed under ALI. No significant cytotoxicity was observed after 24 h exposure to ENP liquid suspensions, although aerosolised ENP clearly affected cell viability and LDH release. In general, all ENP increased primary DNA damage regardless of the exposure mode, where an increase in DNA strand-breaks was only detected under submerged conditions. Our data show that at relevant occupational concentrations, the selected ENP exert mild toxicity to alveolar epithelial cells and exposure at ALI might be the most suitable choice when assessing ENP toxicity in respiratory models under realistic exposure conditions.This research was funded by CERASAFE (www.cerasafe.eu; accessed on 26 October 2021), with the support of ERA-NET SIINN (project id:16) and the Portuguese Foundation for Science and Technology (FCT; SIINN/0004/2014). This work was also supported by the NanoBioBarriers project (PTDC/MED-TOX/31162/2017), co-financed by the Operational Program for Competitiveness and Internationalization (POCI) through European Regional Development Funds (FEDER/FNR) and FCT; Spanish Ministry of Science and Innovation (projects PCIN-2015-173-C02-01 and CEX2018-000794-S-Severo Ochoa), and by the Romanian National Authority for Scientific Research and Innovation (CCCDI-UEFISCDI, project number 29/2016 within PNCDI III). M.J. Bessa (SFRH/BD/120646/2016) and F. Brandão (SFRH/BD/101060/2014) are recipients of FCT PhD scholarships under the framework of Human Capital Operating Program (POCH) and European Union funding. The Doctoral Program in Biomedical Sciences, of the ICBAS—University of Porto, offered additional funds. S. Fraga thanks FCT for funding through program DL 57/2016–Norma transitória (Ref. DL-57/INSA-06/2018). Thanks are also due to FCT/MCTES for the financial support to EPIUnit (info:eu-repo/grantAgreement/FCT/6817 - DCRRNI ID/UIDB/04750/2020/PT)

First spectral emissivity study of a solar selective coating in the 150 to 600 C temperature range

A complete experimental study of temperature dependence of the total spectral emissivity has been performed, for the first time, for absorber reflector selective coatings used in concentrated solar power (CSP) systems for energy harvesting. The coating consist of double cermet layers of silicon oxide with different amounts of molybdenum over a silver infrared mirror layer. The experimental measurements were carried out by a high accurate radiometer (HAIRL) with controlled atmosphere in the mid-infrared and for temperatures between 150 and 600 C. The spectral emissivity is nearly constant in this temperature range. Therefore, the temperature dependence of the total emissivity is given by Planck function. These results were compared with those obtained with the usual calculus using room temperature reflectance spectrum. Finally, the performance of the coating was analyzed by comparison of coated respect to non-coated stainless steel.Comment: 6 pages, 10 figure

Moving into advanced nanomaterials. Toxicity of rutile TiO2 nanoparticles immobilized in nanokaolin nanocomposites on HepG2 cell line

Immobilization of nanoparticles on inorganic supports has been recently developed, resulting in the creation of nanocomposites. Concerning titanium dioxide nanoparticles (TiO2 NPs1), these have already been developed in conjugation with clays, but so far there are no available toxicological studies on these nanocomposites. The present work intended to evaluate the hepatic toxicity of nanocomposites (C-TiO22), constituted by rutile TiO2 NPs immobilized in nanokaolin (NK3) clay, and its individual components. These nanomaterials were analysed by means of FE-SEM4 and DLS5 analysis for physicochemical characterization. HepG2 cells were exposed to rutile TiO2 NPs, NK clay and C-TiO2 nanocomposite, in the presence and absence of serum for different exposure periods. Possible interferences with the methodological procedures were determined for MTT,6 neutral red uptake, alamar blue (AB), LDH,7 and comet assays, for all studied nanomaterials. Results showed that MTT, AB and alkaline comet assay were suitable for toxicity analysis of the present materials after slight modifications to the protocol. Significant decreases in cell viability were observed after exposure to all studied nanomaterials. Furthermore, an increase in HepG2 DNA damage was observed after shorter periods of exposure in the absence of serum proteins and longer periods of exposure in their presence. Although the immobilization of nanoparticles in micron-sized supports could, in theory, decrease the toxicity of single nanoparticles, the selection of a suitable support is essential. The present results suggest that NK clay is not the appropriate substrate to decrease TiO2 NPs toxicity. Therefore, for future studies, it is critical to select a more appropriate substrate for the immobilization of TiO2 NPs

Gold nanorods induce early embryonic developmental delay and lethality in zebrafish (Danio rerio)

Due to their unique electronic and optical features, gold nanoparticles (AuNP) have received a great deal of attention for application in different fields such as catalysis, electronics, and biomedicine. The large-volume manufacturing predicted for future decades and the inevitable release of these substances into the environment necessitated an assessment of potential adverse human and ecological risks due to exposure to AuNP. Accordingly, this study aimed to examine the acute and developmental toxicity attributed to a commercial suspension of Au nanorods stabilized with cetyltrimethylammonium bromide (CTAB-AuNR) using early embryonic stages of zebrafish (Danio rerio), a well-established model in ecotoxicology. Zebrafish embryos were exposed to CTAB-AuNR (0–150 µg/L) to determine for developmental assessment until 96 hr post fertilization (hpf) and lethality. Uptake of CTAB-AuNR by embryos and nanoparticles potential to induce DNA damage was also measured at 48 and 96 hpf. Analysis of the concentration-response curves with cumulative mortality at 96 hpf revealed a median lethal concentration (LC50,96h) of 110.2 μg/L. At sublethal concentrations, CTAB-AuNR suspensions were found to produce developmental abnormalities such as tail deformities, pericardial edema, decreased body length, and delayed eye, head, and tail elongation development. Further, less than 1% of the initial concentration of CTAB-AuNR present in the exposure media was internalized by zebrafish embryos prior to (48 hpf) and after hatching (96 hpf). In addition, no marked DNA damage was detected in embryos after exposure to CTAB-AuNR. Overall, CTAB-AuNR suspensions produced lethal and sublethal effects on zebrafish embryos with possible repercussions in fitness of adult stages. However, these results foresee a low risk for fish since the observed effects occurred at concentrations above the levels expected to find in the aquatic environment.This work was supported by FEDER funds through the program COMPETE—Programa Operacional Factores de Competitividade,” and by the Portuguese Foundation for Science and Technology (FCT), within the CESAM’s strategic program (UID/AMB/50017/2013), the research project Synchrony (PTDC/AAG-MAA/2140/2012). This research was also partially supported by FCT and the European Regional Development Fund (ERDF), in the framework of the program PT2020 and of ERA-NET SIINN through project NanoToxClass (ERA-SIINN/0001/2013). The materials characterization performed was also developed in the scope of the project CICECO—Aveiro Institute of Materials, POCI-01-0145-FEDER-007679 (Ref. FCT UID/CTM/50011/2013), financed by national funds through the FCT/MEC and when applicable co-financed by FEDER under the PT2020 Partnership Agreement, and also the project MAGICOAT (PTDC/CTM-BIO/2170/2014). JT thanks FCT for the research grant IF/00347/2013

Genetic, environmental and stochastic factors in monozygotic twin discordance with a focus on epigenetic differences

PMCID: PMC3566971This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited