List of Abstracts 2019: SESSION D - MONITORING AND TOXICITY OF NANOMATERIALS
Date: October 17, 2019
There has been a growing concern that long-term exposure to ambient ultrafine particles contributes to the development of neurological and neurodegenerative disorders like Alzheimer's disease (AD). Rodent inhalation studies with these particles have revealed hallmarks of oxidative stress, neuroinflammation and neurotoxicity as well as an accelerated formation of AD-characteristic amyloid beta plaques within specific brain regions. The experimental findings are in line with epidemiological studies that demonstrated associations between exposure to (ultrafine) particles or traffic-related air pollution and cognitive function decline. Together, such epidemiological and toxicological investigations also raised concern that, besides these unintentionally generated nanoparticles, manufactured nanoparticles could harm the central nervous system. This presentation will give an overview about recent and ongoing neurotoxicological investigations with a variety of manufactured nanoparticles including TiO2, Ag, SiO2 and CeO2. The cellular and molecular mechanisms whereby nanoparticles may cause or accelerate neurotoxicity and neurodegenerative effects will be presented in relation to their physicochemical properties and by taking into account their dose and route of exposure.
ACKNOWLEDGEMENTS: This work has beens supported by the German Federal Ministry of Education and Research (BMBF/InnoSysTox-Verbund 031L0020A) and the the European Union’s Seventh Framework Programme (FP7/2007-2013) under grant agreement n° NMP4-LA-2013-310451 (NanoMile).
The tumultuous development of nanotechnology and the increasing use of engineered nanomaterials (ENMs) in different products and applications are considered a potential threat for human health but also for the environment. Studies regarding the impacts of such materials on biota and their potential transfer along the food web are still at an early stage. Released ENMs can accumulate into environmental compartments where they can establish complex interactions with biota. Different studies, regarding ENMs, focus the attention on crops, but the effects of these new materials on spontaneous species are completely unknown and poorly investigated. Cerium oxide nanoparticles (nCeO2) are one of the most widely utilized ENMs in Europe and have a great potential to accumulate and affect the environment because of their widespread applications in commercial products. A pot soil experiment was carried out in greenhouse conditions in order to observe the response of two spontaneous plant species (Diplotaxis tenuifolia L. DC. and Holcus lanatus L.) to different concentrations of nCeO2 having different dimensions (25 nm and 50 nm, respectively). Plant growth parameters and nCeO2 uptake and bioaccumulation were investigated. In both species, nCeO2 treatments increase the development of roots if it is compared with control. The same comparison could be done for leaf area, with higher values in treated plants than in control ones. ICP - MS analysis highlight that, at the same high concentration of nCeO2, plants absorb more 25 nm particles than 50 nm, because nCeO2 50 nm tend to join together and their uptake is more difficult.
Copper oxide nanoparticles (CuO NPs) have a widespread use in industry, chemistry, in production of electronic devices and as an antimicrobial agent. Although copper is an important biogenic element, CuO NPs are toxic with the ability to induce oxidative stress, apoptosis, cell cycle arrest or DNA damage. For humans, the inhalation route is the most common way of exposure to CuO NPs. In the body, CuO NPs may be either deposited in the lungs, or transported to other organs. Their presence usually causes oxidative stress or inflammatory responses, consequently leading to DNA damage. In this study, we investigated the effect of CuO NPs inhalation on DNA damage in a group of researches conducting animal exposure experiments. The subjects were exposed to various metal oxide nanoparticles, including CuO NPs, by inhalation for an average of 4.9 ± 0.4 years. The average mass concentration of Cu in the air during the experiment was 7.3 ± 3.2 ng/m3. Subjects not exposed to nanoparticles served as a control group. We applied micronucleus assay using Human Pan Centromeric probes to detect DNA damage and to distinguish between the frequency of centromere positive (CEN+) and centromere negative (CEN−) micronuclei (MN) in the binucleated cells. We did not find differences between both groups for either mean MN frequency (10.38 ± 2.50 vs. 11.88 ± 3.01 MN/1000 binucleated cells), or CEN+/CEN- ratio (58%/42% vs. 55%/45%), for the exposed and controls, respectively. In conclusion, inhalation of CuO NPs at this low-level exposure had no effect on chromosomal losses and/or breaks.
The infrared light sources and detectors offer a direct, rapid, and often highly selective means of measuring pollutant gas species. Therefore, Mid-IR light sources and sensors for detecting pollutants are urgently needed for the sake of environmental and health protection. So far semiconductor light sources for infrared and visible spectral range are widely used in telecommunications and lighting. Using Mid-IR light sources and sensors for mid-infrared spectral range allow developing portable sensors with high reliability and adequate accuracy that can be successfully applied in different areas for matter analysis purposes. Using GaInAsSb/AlGaAsSb heterostructures lattice matched to GaSb substrate allowed one to create light sources for 2-3 μm spectral range or even beyond. This study mainly focused on the fabrication of the photonic-crystal surface-emitting lasers on the gallium antimonide (GaSb) substrates. The optically pumped surface-emitting laser was achieved by fabrication of photonic-crystals with five different periods on the top of the sample surface. The corresponding resonance wavelengths, as well as the dependence on the photonic crystal periods and the threshold power are discussed. Effects of different etching depths on the emission wavelength, threshold power, and mode shifting were investigated for the lasers with the five different photonic-crystal periods. By measuring the energy band structure, we were able to confirm the photonic crystal mode was on the edge of the energy band at the Γ point.
Nanomaterials are researched for their possible fast and easy detection of drug content and concentration in biological applications and clinical practice. Diamond nanoparticles (nanodiamond, ND) possess many beneficial and unique chemical, physical and electrical properties, are non-toxic, and are frequently used as biosensors. This work is a computational study of adsorption of 1-EN-142 drug molecule (developed for Alzheimer treatment [Nepovimova et al., J. Medicinal Chem. 57 (2014) 8576] with the molecular formula of C25H22ClN3O3 on ND surfaces via 16-mercaptohexadecyl)trimethylammonium bromide (MTAB) linker. Density functional theory (DFT) with the hybrid B3LYP functional together with GD3BJ dispersion corrections are used. First, optimizations of the separate drug molecule, MTAB and ND slab are performed. Second, their mutual interactions, including multiply non-equivalent physisorbed and chemisorbed positions, are optimized. ND is represented by an edge-like structure with surface terminated with an amorphous surface layer of carbon saturated by hydrogen or oxygen atoms in different positions, including ether, epoxide, peroxide and ketone surface functional groups. On the optimized structures, analysis of binding and interaction energies is performed as well as HOMO-LUMO gap calculations, and the spatial localization electron density corresponding to the frontier molecular orbitals is evaluated. It is shown that the drug molecule is wrapped non-covalently around the charged MTAB head. The drug-MTAB complex is further assembled on ND via physisorption in upright or planar geometry configuration depending on the ND surface chemistry. Interaction with the MTAB molecule leads to spatial separation of HOMO and LUMO orbitals within the drug molecule, which persists also after interaction with nanodiamonds. The results are correlated with the practical experiments measuring microscopic surface morphology. ACKNOWLEDGEMENTS: The work has been supported by GACR 17-19968S.
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