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Koce J.D.,University of Ljubljana | Drobne D.,University of Ljubljana | Drobne D.,Advanced Materials and Technologies for the Future CO NAMASTE | Klancnik K.,University of Ljubljana | And 3 more authors.
Environmental Toxicology and Chemistry | Year: 2014

The effect of ultraviolet-A irradiated or nonirradiated suspensions of agglomerates of titanium dioxide (TiO2) or silicon dioxide (SiO2) nanoparticles on roots of the onion (Allium cepa) has been studied. The reactive potential of TiO2 nanoparticles, which have photocatalytic potential, and the nonphotocatalytic SiO2 nanoparticles with the same size of agglomerates was compared. The authors measured the activity of antioxidant enzymes glutathione reductase, ascorbate peroxidase, guaiacol peroxidase, and catalase as well as lipid peroxidation to assess the oxidative stress in exposed A. cepa roots. A wide range of concentrations of nanoparticles was tested (0.1-1000μg/mL). The sizes of agglomerates ranged in both cases from 300nm to 600nm, and the exposure time was 24h. Adsorption of SiO2 nanoparticles on the root surface was minimal but became significant when roots were exposed to TiO2 agglomerates. No significant biological effects were observed even at high exposure concentrations of SiO2 and TiO2 nanoparticles individually. Plants appear to be protected against nanoparticles by the cell wall, which shields the cell membrane from direct contact with the nanoparticles. The authors discuss the need to supplement conventional phytotoxicity and stress end points with measures of plant physiological state when evaluating the safety of nanoparticles. Environ Toxicol Chem 2014;33:858-867. © 2013 SETAC.

Millaku A.,LIMNOS Company for Applied Ecology Ltd. | Drobne D.,University of Ljubljana | Drobne D.,Advanced Materials and Technologies for the Future CO NAMASTE | Torkar M.,Slovenian Institute of Metals And Technology | And 4 more authors.
Journal of Hazardous Materials | Year: 2013

We provide data obtained by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) on the interaction of ingested tungsten nanofibers with epithelial cells of the digestive tubes of a test organism Porcellio scaber. Conventional toxicity endpoints including feeding behaviour, weight loss and mortality were also measured in each investigated animal. No toxicity was detected in any of exposed animals after 14 days of feeding on tungsten nanofiber dosed food, but when nanofibers enter the digestive system they can react with epithelial cells of the digestive tubes, becoming physically inserted into the cells. In this way, nanofibers can injure the epithelial cells of digestive gland tubes when they are ingested with food. Our SEM data suggest that peristaltic forces may have an important role, not predicted by in vitro experiments, in the interactions of nanomaterials with digestive intestinal cells. © 2013 Elsevier B.V.

Novak S.,University of Ljubljana | Drobne D.,University of Ljubljana | Drobne D.,Advanced Materials and Technologies for the Future CO NAMASTE | Golobic M.,University of Ljubljana | And 10 more authors.
Environmental Science and Technology | Year: 2013

With a model invertebrate animal, we have assessed the fate of magnetic nanoparticles in biologically relevant media, i.e., digestive juices. The toxic potential and the internalization of such nanoparticles by nontarget cells were also examined. The aim of this study was to provide experimental evidence on the formation of Co2+, Fe2+, and Fe3+ ions from CoFe2O4 nanoparticles in the digestive juices of a model organism. Standard toxicological parameters were assessed. Cell membrane stability was tested with a modified method for measurement of its quality. Proton-induced X-ray emission and low energy synchrotron radiation X-ray fluorescence were used to study internalization and distribution of Co and Fe. Co2+ ions were found to be more toxic than nanoparticles. We confirmed that Co2+ ions accumulate in the hepatopancreas, but Fen+ ions or CoFe2O4 nanoparticles are not retained in vivo. A model biological system with a terrestrial isopod is suited to studies of the potential dissolution of ions and other products from metal-containing nanoparticles in biologically complex media. © 2013 American Chemical Society.

Novak S.,University of Ljubljana | Drobne D.,University of Ljubljana | Drobne D.,Advanced Materials and Technologies for the Future CO NAMASTE | Vaccari L.,Elettra - Sincrotrone Trieste | And 5 more authors.
Environmental Science and Technology | Year: 2013

Tungsten nanofibers are recognized as biologically potent. We study deviations in molecular composition between normal and digestive gland tissue of WOx nanofibers (nano-WOx) fed invertebrate Porcellio scaber (Iosopda, Crustacea) and revealed mechanisms of nano-WOx effect in vivo. Fourier Transform Infrared (FTIR) imaging performed on digestive gland epithelium was supplemented by toxicity and cytotoxicity analyses as well as scanning electron microscopy (SEM) of the surface of the epithelium. The difference in the spectra of the Nano-WOx treated and control cells showed up in the central region of the cells and were related to lipid peroxidation, and structural changes of nucleic acids. The conventional toxicity parameters failed to show toxic effects of nano-WOx, whereas the cytotoxicity biomarkers and SEM investigation of digestive gland epithelium indicated sporadic effects of nanofibers. Since toxicological and cytological measurements did not highlight severe effects, the biochemical alterations evidenced by FTIR imaging have been explained as the result of cell protection (acclimation) mechanisms to unfavorable conditions and indication of a nonhomeostatic state, which can lead to toxic effects. © 2013 American Chemical Society.

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