To Duckweeds (\u3cem\u3eLandoltia punctata\u3c/em\u3e), Nanoparticulate Copper Oxide is More Inhibitory than the Soluble Copper in the Bulk Solution

CuO nanoparticles (CuO-NP) were synthesized in a hydrogen diffusion flame. Particle size and morphology were characterized using scanning mobility particle sizing, Brunauer–Emmett–Teller analysis, dynamic light scattering, and transmission electron microscopy. The solubility of CuO-NP varied with both pH and presence of other ions. CuO-NP and comparable doses of soluble Cu were applied to duckweeds, Landoltia punctata. Growth was inhibited 50% by either 0.6 mg L−1 soluble copper or by 1.0 mg L−1 CuO-NP that released only 0.16 mg L−1 soluble Cu into growth medium. A significant decrease of chlorophyll was observed in plants stressed by 1.0 mg L−1 CuO-NP, but not in the comparable 0.2 mg L−1 soluble Cu treatment. The Cu content of fronds exposed to CuO-NP is four times higher than in fronds exposed to an equivalent dose of soluble copper, and this is enough to explain the inhibitory effects on growth and chlorophyll content

Novel lanthanide-labeled metal oxide nanoparticles improve the measurement of in vivo clearance and translocation

Abstract The deposition, clearance and translocation of europium-doped gadolinium oxide nanoparticles in a mouse lung were investigated experimentally. Nanoparticles were synthesized by spray flame pyrolysis. The particle size, crystallinity and surface properties were characterized. Following instillation, the concentrations of particles in organs were determined with inductively coupled plasma mass spectrometry. The protein corona coating the nanoparticles was found to be similar to the coating on more environmentally relevant nanoparticles such as iron oxide. Measurements of the solubility of the nanoparticles in surrogates of biological fluids indicated very little propensity for dissolution, and the elemental ratio of particle constituents did not change, adding further support to the contention that intact nanoparticles were measured. The particles were intratracheally instilled into the mouse lung. After 24 hours, the target organs were harvested, acid digested and the nanoparticle mass in each organ was measured by inductively coupled plasma mass spectrometry (ICP-MS). The nanoparticles were detected in all the studied organs at low ppb levels; 59% of the particles remained in the lung. A significant amount of particles was also detected in the feces, suggesting fast clearance mechanisms. The nanoparticle system used in this work is highly suitable for quantitatively determining deposition, transport and clearance of nanoparticles from the lung, providing a quantified measure of delivered dose.</p

Sublethal Effects of CuO Nanoparticles on Mozambique Tilapia (<i>Oreochromis mossambicus</i>) Are Modulated by Environmental Salinity

<div><p>The increasing use of manufactured nanoparticles (NP) in different applications has triggered the need to understand their putative ecotoxicological effects in the environment. Copper oxide nanoparticles (CuO NP) are toxic, and induce oxidative stress and other pathophysiological conditions. The unique properties of NP can change depending on the characteristics of the media they are suspended in, altering the impact on their toxicity to aquatic organisms in different environments. Here, Mozambique tilapia (<i>O. mossambicus</i>) were exposed to flame synthesized CuO NP (0.5 and 5 mg·L⁻¹) in two environmental contexts: (a) constant freshwater (FW) and (b) stepwise increase in environmental salinity (SW). Sublethal effects of CuO NP were monitored and used to dermine exposure endpoints. Fish exposed to 5 mg·L⁻¹ CuO in SW showed an opercular ventilation rate increase, whereas fish exposed to 5 mg·L⁻¹ in FW showed a milder response. Different effects of CuO NP on antioxidant enzyme activities, accumulation of transcripts for metal-responsive genes, GSH∶GSSG ratio, and Cu content in fish gill and liver also demonstrate that additive osmotic stress modulates CuO NP toxicity. We conclude that the toxicity of CuO NP depends on the particular environmental context and that salinity is an important factor for modulating NP toxicity in fish.</p></div

Cu-content of liver and gills after CuO NP exposure at different salinities.

<p>Values (ng of Cu per mg of dry weight) are depicted as mean ± SEM. FW0, fresh water; FW0.5, FW plus 0.5 mg·L⁻¹ CuO; FW5, FW plus 5 mg·L⁻¹ CuO; SW0, increasing salinity; SW0.5, SW plus 0.5 mg·L⁻¹ CuO; SW5, SW plus 5 mg·L⁻¹ CuO. Significant different means by Anova analysis are shown with ‡ (<i>P</i> value). Letters denote groups showing non significant differences by Tukey's post-test (<i>P</i><0.05). <i>n</i>×treatment = 5.</p

Expression of metal-responsive genes.

<p>Transcripts levels analysis by qPCR in liver (black bars) and gills (white bars). Transcript accumulation of (<b>A</b>) <i>Cytochrome P450 1A</i> (<i>CYP1A</i>), and (<b>B</b>) <i>Metallothionein</i> (<i>MT</i>). The genes were analyzed by qPCR in gills and liver, and normalized as function of the levels of endogenous control <i>β-Actin</i> gene. FW0, fresh water; FW0.5, FW plus 0.5 mg·L⁻¹ CuO; FW5, FW plus 5 mg·L⁻¹ CuO; SW0, increasing salinity; SW0.5, SW plus 0.5 mg·L⁻¹ CuO; SW5, SW plus 5 mg·L⁻¹ CuO. Results expressed as percentage of relative quantification. Significant different means by Anova on ranks analysis are shown with ‡ (<i>P</i> value), and significant differences between FW-SW at the same CuO NP concentration (Dunn's post test, <i>P</i><0.05) are shown with §. Asterisks represent significant difference compared to the respective FW0 control by Wilcoxon Signed Rank test (*, <i>P</i><0.05; ** <i>P</i><0.025). <i>n</i>×treatment = 5.</p

Characterization of CuO NP used in the present study.

<p>(A) Representative transmission electron microscopy (TEM) images of the CuO NP at two magnifications. The polydisperse size distribution of CuO NP (n = 245) determined from TEM images is shown in the insert. The average size of the NP is shown (mean ± <i>SD</i>). (B) X-Ray diffraction (XRD) pattern of the NP. The X, and Y axes of the XRD represents the angles (2θ) of incident X-ray beam and the corresponding diffraction peak intensity.</p