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Freshwater contamination by metals can come from a variety of sources and be damaging to wildlife, alter landscapes, and impact human health. Metals removal is desirable not only for improving water quality and preventing adverse effects but also for metals collection and recycling. Nanoadsorption of metals is economically feasible and nanoscale materials exhibit a high surface-area-to-volume ratio that is promising for high adsorption and reactivity. However, the extraordinarily small dimensions of these materials allow them to maneuver biological systems, and combined with high reactivity, this translocation can result in toxicity. In this work, nanoparticles (NPs) composed of a magnetite core coated in hydroxyapatite (HA) and functionalized for adsorption with titanium dioxide (TiHAMNPs) were synthesized. The magnetic core enabled NP retrieval, while HA enhanced adsorption and minimized toxicity. Here, synthesis and characterization are presented, revealing a stable NP structure exhibiting a near neutral surface charge. Results of adsorption studies showed that as compared to silica-coated magnetite nanoparticles (SiMNPs), traditionally used for this application, TiHAMNPs exhibited significantly higher adsorption (43.28% more Cu removal) after 24 h. The equilibrium rate constant for the adsorption of Cu by TiHAMNPs was 0.0003 g/(min*mg) and TiHAMNP adsorption data indicated that TiHAMNPs adsorb metals in a monolayer at the particle surface with a maximum capacity of 2.8 mmol/g. Metabolic and toxicity assays showed TiHAMNPs were highly biocompatible as compared to SiMNPs. This work also explores rare earth element (REE) separation applications of TiHAMNPs, finding that TiHAMNPs may provide a promising alternative for REE retrieval and/or separation. [ABSTRACT FROM AUTHOR]

Recently, nanomaterials, especially titanium-based nanomaterials, have a great potential for decolorization of textile dye effluents. In this article, the nanofibrillar filters functionalized with titanium nanoparticle (nTi) were designed to improve dyeing wastewater decolorization. Pristine polypropylene (PP) and nTi-PP nanocomposite nonwovens were produced as a photocatalyzer by melt-electrospinning process. The average diameter of pristine PP- and nTi-PP nanocomposite melt-electrospun fibers was found average as 700 ± 0.3 and 800 ± 0.4 nm, respectively. Before functionalization with nTi, the surface of fabrics was activated by a technique using glutaraldehyde (GA) and polyethyleneimine to improve decomposition activity. Scanning electron microscopy (SEM) results revealed that titanium nanoparticles were deposited uniformly on the nanofibers. X-ray photon spectroscopy (XPS) results confirmed the presence of titanium nanoparticles and generation of amine groups after modification. Photocatalytic performance of nTi-loaded pristine and nanocomposite melt-electrospun filters was investigated by using methyl orange (MO) as a model compound. The decolorization experiments were carried out by varying initial dye concentration (10, 20, 40 mg/L), pH (2, 5, and 9), and loaded TiO amount (1 and 2 %). According to photocatalytic decolarization test results, nTi-loaded GA-treated pristine or nTi-PP nanocomposite fabric filter has better properties compared to GA-untreated group from point of photocatalytic efficiency, especially over 90 % decolorization efficiency at GA-treated pristine and nTi-PP composite PP fabrics. The complete decolarization of MO was observed at pH value of 5, photocatalyst concentration of 20 mg/L, and 1 % nTi-loading after 3 h. The results show that surface activated PP nonwovens, which is introduced Ti nanoparticles into and onto the structure, a good photocatalytic activity. [ABSTRACT FROM AUTHOR]

Recent advances in nanotechnology have induced a widespread production and application of nanomaterials. As a consequence, an increasing number of workers are expected to undergo exposure to these xenobiotics, while the possible hazards to their health remain not being completely understood. In this context, biological monitoring may play a key role not only to identify potential hazards from and to evaluate occupational exposure to nanomaterials, but also to detect their early biological effects to better assess and manage risks of exposure in respect of the health of workers. Therefore, the aim of this review is to provide a critical evaluation of potential biomarkers of nanomaterial exposure and effect investigated in human and animal studies. Concerning exposure biomarkers, internal dose of metallic or metal oxide nanoparticle exposure may be assessed measuring the elemental metallic content in blood or urine or other biological materials, whereas specific molecules may be carefully evaluated in target tissues as possible biomarkers of biologically effective dose. Oxidative stress biomarkers, such as 8-hydroxy-deoxy-guanosine, genotoxicity biomarkers, and inflammatory response indicators may also be useful, although not specific, as biomarkers of nanomaterial early adverse health effects. Finally, potential biomarkers from 'omic' technologies appear to be quite innovative and greatly relevant, although mechanistic, ethical, and practical issues should all be resolved before their routine application in occupational settings could be implemented. Although all these findings are interesting, they point out the need for further research to identify and possibly validate sensitive and specific biomarkers of exposure and effect, suitable for future use in occupational biomonitoring programs. A valuable contribution may derive from the studies investigating the biological behavior of nanomaterials and the factors influencing their toxicokinetics and reactivity. In this context, the application of the most recent advances in analytical chemistry and biochemistry to the biological monitoring of nanomaterial exposure may be also useful to detect and define patterns and mechanisms of early nanospecific biochemical alterations. [ABSTRACT FROM AUTHOR]

The paper demonstrates an application of photovoltaic effect in the research of nanomaterials and hybrid structures of polymers with nanoparticles. Photovoltage (PV) measurement was utilized for estimating the size of CdS and ZnO nanoparticles and diagnostics of hybrid structures with poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV), namely nano-CdS/MEH-PPV and nano-ZnO/MEH-PPV. CdS average nanocrystal diameters 4.0 and 4.8 nm were calculated from the onset values of energies corresponding to the steep increase in the PV signals using the effective mass model. The range of size of ZnO particles was from about 5 up to 50 nm. Nanoparticle distribution obtained by transmission electron microscopy (TEM) measurements shows that the calculated diameters agree fairly well with the size of nanoparticles with the highest occurrence. The PV spectrum represents a sum of the spectra corresponding to the various nanoparticle sizes. The distribution of the nanoparticles was also obtained by a simple mathematical treatment of the PV spectra, and agreement with the results of TEM was found. PV and TEM measurements were performed on commercial CdS and ZnO nanoparticles and on CdS nanoparticles prepared in our laboratory. We employ triethanolamine as a protective agent to cover the surface of CdS nanoparticles. Nano-CdS/MEH-PPV and nano-ZnO/MeH-PPV hybrid structures were prepared, and influence of the particles on charge transport was shown by the PV spectra measurements. [ABSTRACT FROM AUTHOR]

In this paper, an inhalation health and explosion safety risk assessment methodology for nanopowders is described. Since toxicological threshold limit values are still unknown for nanosized substances, detailed risk assessment on specific plants may not be carried out. A simple approach based on occupational hazard/exposure band expressed in mass concentrations is proposed for nanopowders. This approach is consolidated with an iso surface toxicological scaling method, which has the merit, although incomplete, to provide concentration threshold levels for which new metrological instruments should be developed for proper air monitoring in order to ensure safety. Whenever the processing or use of nanomaterials is introducing a risk to the worker, a specific nano pictogram is proposed to inform the worker. Examples of risk assessment of process equipment (i.e., containment valves) processing various nanomaterials are provided. Explosion risks related to very reactive nanomaterials such as aluminum nanopowders can be assessed using this new analysis methodology adapted to nanopowders. It is nevertheless found that to formalize and extend this approach, it is absolutely necessary to develop new relevant standard apparatuses and to qualify individual and collective safety barriers with respect to health and explosion risks. In spite of these uncertainties, it appears, as shown in the second paper (Part II) that health and explosion risks, evaluated for given MWCNTs and aluminum nanoparticles, remain manageable in their continuous fabrication mode, considering current individual and collective safety barriers that can be put in place. The authors would, however, underline that peculiar attention must be paid to non-continuous modes of operations, such as process equipment cleaning steps, that are often under-analyzed and are too often forgotten critical steps needing vigilance in order to minimize potential toxic and explosion risks. [ABSTRACT FROM AUTHOR]

Nanometric-sized bimetallic Pt-Cu and Pt-Ag nanoparticles protected with PVP were synthesized using a modified protocol of the alkaline polyol method. The nanoparticles were characterized using a series of experimental methods (TEM, XPS, and XRD) to elucidate their morphology, structure, and chemical state. The Pt-Cu powder consisted of nanoparticles with well-defined spherical morphology and a mean diameter of 2.8 nm. In the case of the Pt-Ag system, the small nanoparticles of around 2 nm showed an interesting tendency to assemble in 1D structure, generally with a filament-like morphology. The Pt-Cu and Pt-Ag nanoparticles supported on TiO showed good and stable activity for methanol mineralization. The formation of hydrogen along with CO as reaction products suggests that the supported bimetallic nanoparticles are promising materials for energy-oriented applications, as well as for photochemical abatement of organic pollutants. [ABSTRACT FROM AUTHOR]

Metallic nanoparticles have attracted a particular interest in scientific research and industrial applications due to their unique size-dependent physical and chemical properties. An eco-friendly and cost-effective synthesis method called electrical discharge enables large scale production of metallic nanoparticles. Systematic investigations of such synthesized metallic nanoparticles help to optimize the synthesis process and improve the product quality. In this work, for the first time we have investigated the diffuse interfacial boundary nanostructures of the metallic nanoparticles, which were synthesized under different conditions by electrical glow and arc discharges in the carrier gas, by means of a small- and wide-angle X-ray scattering (SWAXS) technique using a laboratory X-ray source. Meanwhile, this unique SWAXS technique allows simultaneous study of the primary particle size, morphology, and crystallinity. The metallic nanoparticles (copper and nickel) under investigation cover a size range of 10–80 nm, and the determined thickness of the diffuse boundary nanostructured layer of metallic nanoparticles is in the range of 1–3 nm. The experimental results obtained by SWAXS were compared to the TEM/EDX observation and the XRD reference patterns from RRUFF database, and a good agreement was found. Our SWAXS investigations indicated that the existence of a diffuse nanostructured solid layer on the synthesized metallic nanoparticle surface causes a negative deviation of the scattering intensity $$\left( {I \propto q^{ - \alpha } ,\;\alpha > 4} \right)$$ I ∝ q - α , α > 4 from Porod’s law which corresponds to the case of ideal two-phase particle systems with sharp boundaries $$\left( {I \propto q^{ - \alpha } ,\;\alpha = 4} \right)$$ I ∝ q - α , α = 4 . This implies that the electron density profile is not sharp but changes gradually between two phases, and hence the exponent α is greater than four. Two electron density profile models, sigmoidal electron-density gradient model and linear electron-density gradient model, have been taken into account in determining the thickness of the diffuse boundary nanostructured layer. Combined with the SWAXS experimental results, the possible mechanisms of the formation of the diffuse boundary nanostructured layer of the metallic nanoparticles synthesized by electrical glow and arc discharges in the gas phase have been discussed in detail. [ABSTRACT FROM AUTHOR]

Nanotechnology gives us materials with enhanced or completely new properties. At the same time, inhalation of manufactured nano-objects has been related to an array of adverse biological effects. We characterized particle emissions, which occurred during maintenance of common metal nanoparticle generators and contrasted the properties of the emitted particles with those originally produced by the generators. A new approach using online aerosol mass spectrometry (AMS), for time- and size-resolved measurements of the particle chemical composition, was applied in combination with more conventional techniques for particle sampling and analysis, including electron microscopy. Emissions during maintenance work, in terms of mass and surface area concentration in the size range of 0.02–10 μm, were dominated by large agglomerates (1–5 μm). With AMS, we show that the particle composition depends on both generator type and maintenance task being performed and that the instrument can be used for highly time-resolved selective studies of metal nanoparticle emissions. The emitted agglomerates have a relatively high probability to be deposited in the lower respiratory tract, since the mean particle diameter coincided with a peak in the lung deposition curve. Each of these agglomerates consisted of a very high number (10 3–10 5/agglomerate) of nanometer-sized primary particles originating from the particle synthesis process. This made them possess large surface areas, one of the key properties in nanotoxicology. Similar agglomerates may be emitted in a wide range of processes when nanoparticles are manufactured or handled. The fate of such agglomerates, once deposited in the respiratory tract, is unknown and should therefore be considered in future particle toxicological studies. Our results highlight the importance of including micrometer-sized particles in exposure and emission assessments. [ABSTRACT FROM AUTHOR]

BC and AlN nanoparticles were separately added to solidification processed AZ91/ZK60A hybrid magnesium alloy to improve tensile and compressive properties. In tension, both nanoparticles strengthened the hybrid alloy. However, only BC nanoparticle addition significantly improved the ductility of the hybrid alloy, while AlN nanoparticle addition slightly decreased the ductility of the hybrid alloy. Comparing both nanocomposites as well as monolithic alloy, there was no significant difference in the grain size or crystallographic texture. However, it was possible that the AlN nanoparticle was more chemically reactive with the alloy matrix compared to the BC nanoparticle. Also, it was observed that unlike AlN nanoparticle addition, BC nanoparticle addition enabled the formation of numerous nanoscale stacking faults in the hybrid alloy matrix. Further, it was apparent that the BC nanoparticle promoted the nanoscale precipitation of AlMg intermetallic particles (with particle coarsening thereafter), whereas the AlN nanoparticle did not alter the intermetallic precipitation characteristics in the alloy matrix. Consequently, nano/micro-particle induced high strain zone (HSZ) formation during tensile deformation was more pronounced in the AZ91/ZK60A/BC nanocomposite compared to the AZ91/ZK60A/AlN nanocomposite, rendering the BC nanoparticle significantly greater capability (compared to the AlN nanoparticle) in enhancing the tensile ductility of the hybrid alloy. The promotion of nanoscale precipitation of AlMg intermetallic particles (with particle coarsening thereafter) by the BC nanoparticle also enabled the AZ91/ZK60A/BC nanocomposite to have significantly higher compressive strength (per strain level during deformation) compared to the AZ91/ZK60A/AlN nanocomposite. [ABSTRACT FROM AUTHOR]

The geometrical properties of metallic nanoparticles such as the size and morphology have significant impacts on the structure and stability of the adsorbed biological entities as well as the nanoscale structural performances. To identify the nanoscale intrinsic geometry from the height images by atomic force microscopy (AFM), we developed a curvature-dependent evolution scheme that can eliminate the noise and smoothen the surfaces. The principal curvatures are computed directly from the first and second derivatives of the discrete AFM height data. The principal curvatures and directions correspond to the eigenvalues and eigenvectors of shape operator matrix, respectively. The evolution equation using the principal curvature flows smoothens the images in the corresponding principal directions. For an idealized model, κ flow successfully identifies the major valley lines to represent the boundary of nanoparticles without referring to the phase information, whereas the mean curvature flow eliminates all the minor ones leaving only the major feature of the boundary. To demonstrate the capability of noise removal, smoothing surfaces, the identification of ridge and valley lines, and the extraction of intrinsic geometry, the developed numerical scheme is applied to real AFM data that include the silver nanoparticles of 24 nm diameter and the gold nanoparticles of 33-56 nm diameters. [ABSTRACT FROM AUTHOR]

The microstructure design of TiO nanoparticles for photoanodes is an important issue in optimization of dye-sensitized solar cell (DSSC) performance. Up to date, the nanostructured TiO particles have been extensively employed as active layers. However, less attention has been focused on the development of various TiO nanostructures as the light-scattering layers (LSLs). In the present work, a facile hydrothermal method was utilized to prepare quasi-cube TiO (qcTiO) nanoparticles as the LSL for the DSSC photoanode. The anatase qcTiO nanoparticles had a size distribution of 30-60 nm. The photoconversion efficiency of the cell with the qcTiO LSL was enhanced 12 %, compared to the TiO film without a scattering layer. The above enhancement was further vindicated by the incident photon-to-current efficiency measurement. The effect of the qcTiO LSL on electron transport and charge recombination of the DSSC was studied by electrochemical impedance spectroscopy. The experiment results revealed that the enhanced photovoltaic performance is attributed to the better light-harvesting capacity, longer electron life time, and less charge recombination of the qcTiO nanoparticles. [ABSTRACT FROM AUTHOR]

With rapid advances in nanotechnology and nanomaterials, metallic nanoparticles (MNPs) have become widely used in many different products and industrial processes. Water is an important medium in the transfer and fate of MNPs. Accordingly, the potential for the inadvertent and incidental release of MNPs into aquatic environments through direct release and waste disposal has increased considerably in China in recent years. Environmental health and human safety are two of the greatest challenges facing the expanding nanomaterial field. However, existing knowledge on MNP toxicity is currently insufficient to carry out a comprehensive risk assessment due to a general lack of data related to the environmental distribution of MNPs within aquatic environments. This study provides a summary of MNP production and consumption trends in China by means of statistical changes in MNP discharge and deposition between 2000 and 2010. China was used as a model for aquatic environmental risks associated with MNP consumption and production. MNP pollution of aquatic environments is discussed as well as the challenges that China will face in the future with increasing nanomaterial consumption and pollution. The study concludes with a discussion on managing MNP exposure of aquatic environments in China and its subsequent risks, if any, which may require greater attention. [ABSTRACT FROM AUTHOR]

Among nanomaterials of industrial relevance, metal-based nanoparticles (NPs) are widely used, but their effects on airway cells are relatively poorly characterized. To compare the effects of metal NPs on cells representative of the lung-blood barrier, Calu-3 epithelial cells and Raw264.7 macrophages were incubated with three industrially relevant preparations of TiO NPs (size range 4-33 nm), two preparations of CeO NPs (9-36 nm) and CuO NPs (25 nm). While Raw264.7 were grown on standard plasticware, Calu-3 cells were seeded on permeable filters, where they form a high-resistance monolayer, providing an in vitro model of the airway barrier. Metal NPs, obtained from industrial sources, were characterized under the conditions adopted for the biological tests. Cytotoxicity was assessed with resazurin method in both epithelial and macrophage cells, while epithelial barrier permeability was monitored measuring the trans-epithelial electrical resistance (TEER). In macrophages, titania and ceria had no significant effect on viability in the whole range of nominal doses tested (15-240 μg/cm of monolayer), while CuO NPs produced a marked viability loss. Moreover, only CuO NPs, but not the other NPs, lowered TEER of Calu-3 monolayers, pointing to the impairment of the epithelial barrier. TEER decreased by 30 % at the dose of 10 μg/cm of CuO NPs, compared to untreated control, and was abolished at doses ≥80 μg/cm, in strict correlation with changes in cell viability. These results indicate that (1) CuO NPs increase airway epithelium permeability even at relatively low doses and are significantly toxic for macrophages and airway epithelial cells, likely through the release of Cu ions in the medium; (2) TiO and CeO NPs do not affect TEER and exhibit little acute toxicity for airway epithelial cells and macrophages; and (3) TEER measurement can provide a simple method to assess the impairment of in vitro airway epithelial barrier model by manufactured nanomaterials. [ABSTRACT FROM AUTHOR]

ggregates of phosphatidylcholine-passivated gold nanorods were prepared by the addition of hydrochloric acid in the presence of 6-amino-1-hexanethiol hydrochloride (AHT). The aggregates dried in vacuum formed a solid film showing a metallic gold color. In spite of the absence of the stable surface-wrapping agents, such as balky polymer or thiol-molecules that form stable self-organized films on a gold surface, the dried aggregates dispersed again in water. The redispersed gold nanorods in water did not form aggregates. If the dried nanorods were kept at room temperature for 24 h, they did not disperse in water again; however, at -30 °C, some of gold nanorods could be redispersed in water. At -80 °C, gold nanorods could be redispersed in water as colloidal nanoparticles even after 2 months. The phosphatidylcholine and AHT molecules on the nanorod surfaces contributed to the suppression of the contact of nanorods, which were in the metallic gold color films. [ABSTRACT FROM AUTHOR]