Double oxide shell layer formed on a metal nanoparticle as revealed by aberration corrected (scanning) transmission electron microscopy

Boyd, Robert; Pilch, Iris; Garbrecht, Magnus; Halvarsson, Mats; Helmersson, Ulf

doi:10.1088/2053-1591/1/2/025016

Cited by 8 publications

(8 citation statements)

References 35 publications

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“…Speciation was modeled for 20 mg/L as Cu 2+ for Cu‐NPs as well as for CuCl 2 introduced into tris‐acetate‐phosphate medium using Kropat's trace metal solution. Previous research with Cu‐NPs suggests that copper oxide layers form on the surface of Cu‐NPs exposed to oxygen, so both zerovalent copper and CuO were included in the model . Speciation was identical for each copper source in tris‐acetate‐phosphate medium using Kropat's trace metal solution with or without copper.…”

Section: Methodsmentioning

confidence: 99%

“…As the particles were synthesized as a zerovalent-Cu core with a CuO shell, ICP-OES measurements verified that the oxidized CuO layer promoted Cu-NPs dissolution into the tris-acetate-phosphate media. Indeed previous research with Cu-NPs suggests that copper oxide layers form on the surface of Cu-NPs after exposure to oxygen and affect their reactivity in the medium [32]. Speciation also suggests that CuO from both Cu-NPs and CuCl 2 dissolved NP toxicity depends on copper status of freshwater algae Environ Toxicol Chem 35, 2016 into the same charged species-Cu(Tris) 4 2þ , Cu(Tris) 3 2þ , CuOH(Tris) 2 þ , and Cu(Tris) 2 2þ -but with slightly different proportions.…”

Section: Np Characterizationmentioning

confidence: 97%

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Copper status of exposed microorganisms influences susceptibility to metallic nanoparticles

Reyes

Spitzmiller

Hong-Hermesdorf

et al. 2016

Enviro Toxic and Chemistry

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Although interactions of metallic nanoparticles (NP) with various microorganisms have been previously explored, few studies have examined how metal sensitivity impacts NP toxicity. Herein, we investigated the effects of copper nanoparticles’ (Cu-NPs) exposure to the model alga, Chlamydomonas reinhardtii, in the presence and absence of the essential micronutrient copper. The toxic ranges for Cu-NPs and the ionic control, CuCl2, were determined using a high-throughput ATP-based fluorescence assay. Cu-NPs caused similar mortality in copper-replete and copper-deplete cells (IC50: 14–16 mg/L), but were less toxic than the ionic control, CuCl2 (IC50: 7 mg/L). Using this concentration range, we assessed Cu-NP impacts to cell morphology, copper accumulation, chlorophyll content, and expression of stress genes under both copper supply states. Osmotic swelling, membrane damage, and chloroplast and organelle disintegration were observed by transmission electron microscopy at both conditions. Despite these similarities, copper-deplete cells showed greater accumulation of loosely bound and tightly bound copper after exposure to Cu-NPs. Furthermore, copper-replete cells experienced greater loss of chlorophyll content, 19 % for Cu-NPs, compared to only an 11% net decrease in copper-deplete cells. The tightly bound copper was bioavailable as assessed by reverse-transcriptase quantitative PCR analysis of CYC6, a biomarker for Cu-deficiency. The increased resistance of copper-deplete cells to Cu-NPs suggests that these cells potentially metabolize excess Cu-NPs or better manage sudden influxes of ions. Our findings recommend that toxicity assessments must account for the nutritional status of impacted organisms and use toxicity models based on estimations of the bioavailable fractions.

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Section: Methodsmentioning

confidence: 99%

Section: Np Characterizationmentioning

confidence: 97%

Copper status of exposed microorganisms influences susceptibility to metallic nanoparticles

Reyes

Spitzmiller

Hong-Hermesdorf

et al. 2016

Enviro Toxic and Chemistry

View full text Add to dashboard Cite

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“…Speciation was modeled at 50 mg/L as Cu 2+ for Cu‐NPs as well as CuCl 2 . Previous research with Cu‐NPs suggests that copper oxide layers form on the surface of Cu‐NPs exposed to oxygen, so both zerovalent copper and CuO were included in the model . Although Cu‐NP stocks were stored in the dark at 4°C to prevent oxidation, stocks were not stored anaerobically, so surface oxidation might have occurred.…”

Section: Methodsmentioning

confidence: 99%

Planktonic and biofilm‐grown nitrogen‐cycling bacteria exhibit different susceptibilities to copper nanoparticles

Reyes

Opot

Mahendra

2015

Enviro Toxic and Chemistry

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Proper characterization of nanoparticle (NP) interactions with environmentally relevant bacteria under representative conditions is necessary to enable their sustainable manufacture, use, and disposal. Previous nanotoxicology research based on planktonic growth has not adequately explored biofilms, which serve as the predominant mode of bacterial growth in natural and engineered environments. Copper nanoparticle (Cu-NP) impacts on biofilms were compared with respective planktonic cultures of the ammonium-oxidizing Nitrosomonas europaea, nitrogen-fixing Azotobacter vinelandii, and denitrifying Paracoccus denitrificans using a suite of independent toxicity diagnostics. Median inhibitory concentration (IC50) values derived from adenosine triphosphate (ATP) for Cu-NPs were lower in N. europaea biofilms (19.6 ± 15.3 mg/L) than in planktonic cells (49.0 ± 8.0 mg/L). However, in absorbance-based growth assays, compared with unexposed controls, N. europaea growth rates in biofilms were twice as resilient to inhibition than those in planktonic cultures. Similarly, relative to unexposed controls, growth rates and yields of P. denitrificans in biofilms exposed to Cu-NPs were 40-fold to 50-fold less inhibited than those in planktonic cells. Physiological evaluation of ammonium oxidation and nitrate reduction suggested that biofilms were also less inhibited by Cu-NPs than planktonic cells. Furthermore, functional gene expression for ammonium oxidation (amoA) and nitrite reduction (nirK) showed lower inhibition by NPs in biofilms relative to planktonic-grown cells. These results suggest that biofilms mitigate NP impacts, and that nitrogen-cycling bacteria in wastewater, wetlands, and soils might be more resilient to NPs than planktonic-based assessments suggest.

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“…This is different from the nanoparticles synthesized that can be found in the literature. A metal core and an oxide shell is found when synthesizing copper [41] and iron with the pulsed hollow cathode sputtering process. In a cluster source a titanium core and an oxide shell has been observed [42].…”

Section: Influence On Oxygen Content and Crystal Structurementioning

confidence: 99%

Titanium oxide nanoparticle production using high power pulsed plasmas

Gunnarsson¹

2016

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This thesis covers fundamental aspects of process control when growing titanium oxide nanoparticles in a reactive sputtering process. It covers the influence of oxygen containing gas on the oxidation state of the cathode from which the growth material is ejected, as well as its influence on the particles oxidation state and their nucleation. It was found that a low degree of reactive gases was necessary for nanoparticles of titanium to nucleate. When the oxygen gas was slightly increased, the nanoparticle yield and particle oxygen content increased. A further increase caused a decrease in particle yield which was attributed to a slight oxidation of the cathode. By varying the oxygen flow to the process, it was possible to control the oxygen content of the nanoparticles without fully oxidizing the cathode. Because oxygen containing gases such as residual water vapour has a profound influence on nanoparticle yield and composition, the deposition source was re-engineered to allow for cleaner and thus more stable synthesis conditions. The size of the nanoparticles has been controlled by two means. The first is to change electrical potentials around the growth zone, which allows for nanoparticle size control in the order of 25-75 nm. This size control does not influence the oxygen content of the nanoparticles. The second means of size control investigated was by increasing the pressure. By doing this, the particle size can be increased from 50 -250 nm, however the oxygen content also increases with pressure. Different particle morphologies were found by changing the pressure. At low pressures, mostly spherical particles with weak facets were produced. As the pressure increased, the particles got a cubic shape. At higher pressures the cubic particles started to get a fractured surface. At the highest pressure investigated, the fractured surface became poly-crystalline, giving a cauliflower shaped morphology.

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Double oxide shell layer formed on a metal nanoparticle as revealed by aberration corrected (scanning) transmission electron microscopy

Cited by 8 publications

References 35 publications

Copper status of exposed microorganisms influences susceptibility to metallic nanoparticles

Copper status of exposed microorganisms influences susceptibility to metallic nanoparticles

Planktonic and biofilm‐grown nitrogen‐cycling bacteria exhibit different susceptibilities to copper nanoparticles

Titanium oxide nanoparticle production using high power pulsed plasmas

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