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Nanomaterials, Volume 10, Issue 9 (September 2020) – 275 articles

Cover Story (view full-size image): A synergetic coupling of synchrotron-based in situ X-ray absorption spectroscopy and X-ray diffraction with laboratory in situ Fourier-transform infrared spectroscopy has allowed for detailed characterization of both metal and substrate upon adsorption of ethylene on supported palladium nanoparticles, which is a key step in various catalytic reactions. The analysis of time-resolved data demonstrated continuous dehydrogenation of ethylene to C2H3, C2H2 and C2H species, with its final decomposition into atomic carbon with formation of the palladium carbide phase. View this paper.
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Article
Metal Organic Framework Derived MnO2-Carbon Nanotubes for Efficient Oxygen Reduction Reaction and Arsenic Removal from Contaminated Water
Nanomaterials 2020, 10(9), 1895; https://doi.org/10.3390/nano10091895 - 22 Sep 2020
Cited by 3 | Viewed by 1022
Abstract
Even though manganese oxides are attractive materials for batteries, super-capacitors and electro-catalysts for oxygen reduction reactions, in most practical applications MnO2 needs to be hybridized with conductive carbon nano-structures to overcome its inherent poor electrical conductivity. In this manuscript we report microwave-assisted [...] Read more.
Even though manganese oxides are attractive materials for batteries, super-capacitors and electro-catalysts for oxygen reduction reactions, in most practical applications MnO2 needs to be hybridized with conductive carbon nano-structures to overcome its inherent poor electrical conductivity. In this manuscript we report microwave-assisted synthesis of MnO2 embedded carbon nanotubes (MnO2@CNT) from Mn-H3BTC (benzene-1,3,5-carboxylic acid) metal organic frameworks (MOF) precursors. Using graphene oxide as microwave susceptible surface, MnO2 nano-particles embedded in three dimensional reduced graphene oxide (rGO) -CNT frameworks (MnO2@CNT-rGO) were synthesized which when applied as electro-catalysts in oxygen reduction reaction (ORR) demonstrated comparable half-wave potential to commercial Pt/C, better stability, and excellent immunity to methanol crossover effect in alkaline media. When carbon fiber (CF) was used as substrate, three-dimensional MnO2@CNT-CF were obtained whose utility as effective adsorbents for arsenic removal from contaminated waters is demonstrated. Full article
(This article belongs to the Special Issue Microwave Technology and Nanomaterials: Synthesis and Application)
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Review
Ferritin Nanocage: A Versatile Nanocarrier Utilized in the Field of Food, Nutrition, and Medicine
Nanomaterials 2020, 10(9), 1894; https://doi.org/10.3390/nano10091894 - 22 Sep 2020
Cited by 2 | Viewed by 1051
Abstract
Compared with other nanocarriers such as liposomes, mesoporous silica, and cyclodextrin, ferritin as a typical protein nanocage has received considerable attention in the field of food, nutrition, and medicine owing to its inherent cavity size, excellent water solubility, and biocompatibility. Additionally, ferritin nanocage [...] Read more.
Compared with other nanocarriers such as liposomes, mesoporous silica, and cyclodextrin, ferritin as a typical protein nanocage has received considerable attention in the field of food, nutrition, and medicine owing to its inherent cavity size, excellent water solubility, and biocompatibility. Additionally, ferritin nanocage also serves as a versatile bio-template for the synthesis of a variety of nanoparticles. Recently, scientists have explored the ferritin nanocage structure for encapsulation and delivery of guest molecules such as nutrients, bioactive molecules, anticancer drugs, and mineral metal ions by taking advantage of its unique reversible disassembly and reassembly property and biomineralization. In this review, we mainly focus on the preparation and structure of ferritin-based nanocarriers, and regulation of their self-assembly. Moreover, the recent advances of their applications in food nutrient delivery and medical diagnostics are highlighted. Finally, the main challenges and future development in ferritin-directed nanoparticles’ synthesis and multifunctional applications are discussed. Full article
(This article belongs to the Special Issue Advances in Food Nanotechnology)
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Article
Electrospinning Synthesis of Carbon-Supported Pt3Mn Intermetallic Nanocrystals and Electrocatalytic Performance towards Oxygen Reduction Reaction
Nanomaterials 2020, 10(9), 1893; https://doi.org/10.3390/nano10091893 - 22 Sep 2020
Cited by 1 | Viewed by 823
Abstract
To realize the large-scale application of fuel cells, it is still a great challenge to improve the performance and reduce the cost of cathode catalysts towards oxygen reduction reaction (ORR). In this work, carbon-supported ordered Pt3Mn intermetallic catalysts were prepared by [...] Read more.
To realize the large-scale application of fuel cells, it is still a great challenge to improve the performance and reduce the cost of cathode catalysts towards oxygen reduction reaction (ORR). In this work, carbon-supported ordered Pt3Mn intermetallic catalysts were prepared by thermal annealing electrospun polyacrylonitrile nanofibers containing Platinum(II) acetylacetonate/ Manganese(III) acetylacetonate. Compared with its counterparts, the ordered Pt3Mn intermetallic obtained at 950 °C exhibits a more positive half-potential and higher kinetic current density during the ORR process. Benefiting from their defined stoichiometry and crystal structure, the Mn atoms in Pt3Mn intermetallic can modulate well the geometric and electronic structure of surface Pt atoms, endowing Pt3Mn catalyst with an enhanced ORR catalytic activity. Moreover, it also has a better catalytic stability and methanol tolerance than commercial Pt/C catalyst. Our study provides a new strategy to fabricate a highly active and durable Pt3Mn intermetallic electrocatalyst towards ORR. Full article
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Article
Polyethylene Glycol as Shape and Size Controller for the Hydrothermal Synthesis of SrTiO3 Cubes and Polyhedra
Nanomaterials 2020, 10(9), 1892; https://doi.org/10.3390/nano10091892 - 21 Sep 2020
Cited by 1 | Viewed by 796
Abstract
Understanding the correlation between the morphological and functional properties of particulate materials is crucial across all fields of physical and natural sciences. This manuscript reports on the investigation of the effect of polyethylene glycol (PEG) employed as a capping agent in the synthesis [...] Read more.
Understanding the correlation between the morphological and functional properties of particulate materials is crucial across all fields of physical and natural sciences. This manuscript reports on the investigation of the effect of polyethylene glycol (PEG) employed as a capping agent in the synthesis of SrTiO3 crystals. The crucial influence of PEG on both the shape and size of the strontium titanate particles is revealed, highlighting the effect on the photocurrents measured under UV–Vis irradiation. Full article
(This article belongs to the Section Synthesis, Interfaces and Nanostructures)
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Article
Synthesis of the ZnTiO3/TiO2 Nanocomposite Supported in Ecuadorian Clays for the Adsorption and Photocatalytic Removal of Methylene Blue Dye
Nanomaterials 2020, 10(9), 1891; https://doi.org/10.3390/nano10091891 - 21 Sep 2020
Cited by 8 | Viewed by 923
Abstract
Currently, the study of semiconductor materials is very promising for the photocatalytic remediation of hazardous organic substances present in the air and water. Various semiconductors have been investigated in this interesting photo-assisted methodology, among them metal oxides such as ZnO, TiO2 and [...] Read more.
Currently, the study of semiconductor materials is very promising for the photocatalytic remediation of hazardous organic substances present in the air and water. Various semiconductors have been investigated in this interesting photo-assisted methodology, among them metal oxides such as ZnO, TiO2 and their derivatives. In this study, ZnTiO3/TiO2 was synthesized by the sol-gel method using Ti(OC3H7)4 and Zn(CH3COO)2 · 2H2O as reagents. The role of several conditions such as synthesis temperature and TiO2:ZnO proportion on the morphology and purity of compounds obtained was studied, and the suitable conditions for the synthesis of photocatalysts were determined. Various techniques were used to conduct a systematic investigation on the structural, morphological, and photocatalytic properties of ZnTiO3/TiO2. Scanning Electron Microscopy (SEM) images show that ZnTiO3/TiO2 have a typical particle size of approximately 100 nm with a quasi-spherical shape. The adsorption and photocatalytic activity were investigated by the decolorization of Methylene Blue (MB) as an organic contaminant under UV irradiation both in TiO2 and ZnTiO3/TiO2 supported over some Ecuadorian clays. The materials evaluated were prepared in the shape of 0.2 cm (diameter) and 1.0 cm (length) cylindrical extrudates. The degradation percentage of MB obtained was 85% approximately after 150 min of irradiation. The results obtained allow us to conclude that these synthesized materials can be used as adsorbents and photocatalysts. Full article
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Article
Improving the Cycling Stability of Fe3O4/NiO Anode for Lithium Ion Battery by Constructing Novel Bimodal Nanoporous Urchin Network
Nanomaterials 2020, 10(9), 1890; https://doi.org/10.3390/nano10091890 - 21 Sep 2020
Viewed by 637
Abstract
The development of facile preparation methods and novel three-dimensional structured anodes to improve cycling stability of lithium ion batteries (LIBs) is urgently needed. Herein, a dual-network ferroferric oxide/nickel oxide (Fe3O4/NiO) anode was synthesized through a facile dealloying technology, which [...] Read more.
The development of facile preparation methods and novel three-dimensional structured anodes to improve cycling stability of lithium ion batteries (LIBs) is urgently needed. Herein, a dual-network ferroferric oxide/nickel oxide (Fe3O4/NiO) anode was synthesized through a facile dealloying technology, which is suitable for commercial mass manufacturing. The dual-network with high specific surface area contains a nanoplate array network and a bimodal nanoporous urchin network. It exhibits excellent electrochemical performance as an anode material for LIB, delivering a reversible capacity of 721 mAh g−1 at 100 mA g−1 after 100 cycles. The good lithium storage performance is related to the ample porous structure, which can relieve stress and mitigate the volume change in the charge/discharge process, the interconnected porous network that enhances ionic mobility and permeability, and synergistic effects of two kinds of active materials. The paper provides a new idea for the design and preparation of anode materials with a novel porous structure by a dealloying method and may promote the development of the dealloying field. Full article
(This article belongs to the Section Energy and Catalysis)
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Article
Characterization of Enamel and Dentine about a White Spot Lesion: Mechanical Properties, Mineral Density, Microstructure and Molecular Composition
Nanomaterials 2020, 10(9), 1889; https://doi.org/10.3390/nano10091889 - 21 Sep 2020
Cited by 5 | Viewed by 1054
Abstract
The study focuses on in vitro tracing of some fundamental changes that emerge in teeth at the initial stage of caries development using multiple approaches. The research was conducted on a mostly sound maxillary molar tooth but with a clearly visible natural proximal [...] Read more.
The study focuses on in vitro tracing of some fundamental changes that emerge in teeth at the initial stage of caries development using multiple approaches. The research was conducted on a mostly sound maxillary molar tooth but with a clearly visible natural proximal white spot lesion (WSL). Values of mineral density, reduced Young’s modulus, indentation hardness and creep as well as the molecular composition and surface microstructure of the WSL and bordering dentine area were studied. The results obtained were compared to those of sound enamel and dentine on the same tooth. A decrease of mechanical properties and mineral density both for the WSL and bordering dentine was detected in comparison to the sound counterparts, as well as increase of creep for the enamel WSL. Differences in molecular composition and surface microstructure (including the indenter impressions) were found and described. WSL induces a serious change in the state of not only the visually affected enamel but also surrounding visually intact enamel and dentine in its vicinity. The results provide the basis for future studies of efficacy of minimal invasive treatments of caries. Full article
(This article belongs to the Special Issue Advances in Micro- and Nanomechanics)
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Article
Magnetic and Magneto-Optical Oroperties of Iron Oxides Nanoparticles Synthesized under Atmospheric Pressure
Nanomaterials 2020, 10(9), 1888; https://doi.org/10.3390/nano10091888 - 21 Sep 2020
Cited by 1 | Viewed by 644
Abstract
Magnetite nanoparticles were synthesized by a simple thermal decomposition process, involving only iron (III) nitrate nonahydrate as a precursor, and hexadecylamine as a solvent and stabilizer at reaction temperatures varied from 200 to 380 °C. The results of the structural analysis showed that [...] Read more.
Magnetite nanoparticles were synthesized by a simple thermal decomposition process, involving only iron (III) nitrate nonahydrate as a precursor, and hexadecylamine as a solvent and stabilizer at reaction temperatures varied from 200 to 380 °C. The results of the structural analysis showed that the average crystallite size depends on the reaction temperature and increases from 4.8 to 13.3 nm. The behavior of the coercivity indicates that all synthesized samples are single domain; herewith, it was found that the critical size corresponding to the transition to the superparamagnetic state at room temperature is about 9 nm. The effect of the reaction temperature on changes in the saturation magnetization was studied. It was found that the size effect in the MCD spectra is observed for the IVCT transition and one ISCT transition, and the influence of the reaction temperature on the change in the MCD spectra was discussed. Full article
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Article
Ta Doping Effect on Structural and Optical Properties of InTe Thin Films
Nanomaterials 2020, 10(9), 1887; https://doi.org/10.3390/nano10091887 - 21 Sep 2020
Viewed by 616
Abstract
The objective of this work was to study the influence of Ta doping on the structural, transmittance properties, linear absorption parameter, and nonlinear absorption properties of InTe thin films. The as-deposited samples with different Ta doping concentrations were prepared by a magnetron co-sputtering [...] Read more.
The objective of this work was to study the influence of Ta doping on the structural, transmittance properties, linear absorption parameter, and nonlinear absorption properties of InTe thin films. The as-deposited samples with different Ta doping concentrations were prepared by a magnetron co-sputtering technique and then annealed in nitrogen atmosphere. Structural investigations by X-ray diffraction revealed the tetragonal structure of InTe samples and that the crystallinity decreases with increasing Ta doping concentration. Further structural analysis by Raman spectra also showed good agreement with X-ray diffraction results. The Ta doping concentration and sample thickness determined by energy-dispersive X-ray spectroscopy and scanning electron microscopy increased as Ta dopant increased. In addition, X-ray photoelectron spectroscopic was carried out to analyze the chemical states of the elements. UV–VIS–NIR transmittance spectra were applied to study the transmittance properties and calculate the linear absorption coefficient. Due to Burstein–Moss effect, the absorption edge moved to shorter wavelengths. Meanwhile, the values of band gap were found to increase from 1.71 ± 0.02 eV to 1.85 ± 0.01 eV with the increase of Ta doping concentration. By performing an open aperture Z-scan technique, we found that all Ta-doped InTe samples exhibited two-photon absorption behaviors. The nonlinear optical absorption parameters, such as modulation depth, two-photon absorption coefficient, and two-photon absorption cross-section, decrease with increasing Ta concentration, whereas the damage threshold increases from 176 ± 0.5 GW/cm2 to 242 ± 0.5 GW/cm2. These novel properties show the potential for applications in traditional optoelectronic devices and optical limiters. Full article
(This article belongs to the Special Issue Photonic Nanomaterials)
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Article
Navigation of Silver/Carbon Nanoantennas in Organic Fluids Explored by a Two-Wave Mixing
Nanomaterials 2020, 10(9), 1886; https://doi.org/10.3390/nano10091886 - 21 Sep 2020
Cited by 1 | Viewed by 653
Abstract
Within this work are analyzed third-order nonlinear optical properties with a potential influence on the dynamic mechanics exhibited by metal/carbon nanofluids. The nanofluids were integrated by multiwall carbon nanotubes decorated with Ag nanoparticles suspended in ethanol or in acetone. Optical third-order nonlinearities were [...] Read more.
Within this work are analyzed third-order nonlinear optical properties with a potential influence on the dynamic mechanics exhibited by metal/carbon nanofluids. The nanofluids were integrated by multiwall carbon nanotubes decorated with Ag nanoparticles suspended in ethanol or in acetone. Optical third-order nonlinearities were experimentally explored by vectorial two-wave mixing experiments with a Nd-YAG laser system emitting nanosecond pulses at a 532 nm wavelength. An optically induced birefringence in the metal/organic samples seems to be responsible for a significant modification in density and compressibility modulus in the nanosystems. The measured nonlinear refractive index was associated with a thermal process together with changes in density, compressibility modulus and speed of sound in the samples. Nanofluid diffusivity was studied to characterize the dynamic concentration gradients related to the precipitation of nanostructures in the liquid solutions. The evolution of the nanoparticle density suspended in the nanofluids was considered as a temporal-resolved probabilistic system. It is stated that the incorporation of Ag nanoparticles in carbon nanotubes produces strong mechanical changes in carbon-based nanofluids. According to numerical simulations and optical evaluations, immediate applications for developing dynamic nanoantennas optical logic gates and quantum-controlled metal/carbon systems can be contemplated. Full article
(This article belongs to the Special Issue Applications of Nanofluids)
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Article
Synthesis of Au, Ag, and Au–Ag Bimetallic Nanoparticles Using Pulicaria undulata Extract and Their Catalytic Activity for the Reduction of 4-Nitrophenol
Nanomaterials 2020, 10(9), 1885; https://doi.org/10.3390/nano10091885 - 20 Sep 2020
Cited by 5 | Viewed by 898
Abstract
Plant extract of Pulicaria undulata (L.) was used as both reducing agent and stabilizing ligand for the rapid and green synthesis of gold (Au), silver (Ag), and gold–silver (Au–Ag) bimetallic (phase segregated/alloy) nanoparticles (NPs). These nanoparticles with different morphologies were prepared in two [...] Read more.
Plant extract of Pulicaria undulata (L.) was used as both reducing agent and stabilizing ligand for the rapid and green synthesis of gold (Au), silver (Ag), and gold–silver (Au–Ag) bimetallic (phase segregated/alloy) nanoparticles (NPs). These nanoparticles with different morphologies were prepared in two hours by stirring corresponding metal precursors in the aqueous solution of the plant extracts at ambient temperature. To infer the role of concentration of plant extract on the composition and morphology of NPs, we designed two different sets of experiments, namely (i) low concentration (LC) and (ii) high concentration (HC) of plant extract. In the case of using low concentration of the plant extract, irregular shaped Au, Ag, or phase segregated Au–Ag bimetallic NPs were obtained, whereas the use of higher concentrations of the plant extract resulted in the formation of spherical Au, Ag, and Au–Ag alloy NPs. The as-prepared Au, Ag, and Au–Ag bimetallic NPs showed morphology and composition dependent catalytic activity for the reduction of 4-nitrophenol (4-NPh) to 4-aminophenol (4-APh) in the presence of NaBH4. The bimetallic Au–Ag alloy NPs showed the highest catalytic activity compared to all other NPs. Full article
(This article belongs to the Section Environmental Nanoscience and Nanotechnology)
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Review
Three-Dimensional Cathodes for Electrochemical Reduction of CO2: From Macro- to Nano-Engineering
Nanomaterials 2020, 10(9), 1884; https://doi.org/10.3390/nano10091884 - 20 Sep 2020
Cited by 3 | Viewed by 1389
Abstract
Rising anthropogenic CO2 emissions and their climate warming effects have triggered a global response in research and development to reduce the emissions of this harmful greenhouse gas. The use of CO2 as a feedstock for the production of value-added fuels and [...] Read more.
Rising anthropogenic CO2 emissions and their climate warming effects have triggered a global response in research and development to reduce the emissions of this harmful greenhouse gas. The use of CO2 as a feedstock for the production of value-added fuels and chemicals is a promising pathway for development of renewable energy storage and reduction of carbon emissions. Electrochemical CO2 conversion offers a promising route for value-added products. Considerable challenges still remain, limiting this technology for industrial deployment. This work reviews the latest developments in experimental and modeling studies of three-dimensional cathodes towards high-performance electrochemical reduction of CO2. The fabrication–microstructure–performance relationships of electrodes are examined from the macro- to nanoscale. Furthermore, future challenges, perspectives and recommendations for high-performance cathodes are also presented. Full article
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Article
Ultrasensitive Detection of Tetracycline Using Boron and Nitrogen Co-Doped Graphene Quantum Dots from Natural Carbon Source as the Paper-Based Nanosensing Probe in Difference Matrices
Nanomaterials 2020, 10(9), 1883; https://doi.org/10.3390/nano10091883 - 20 Sep 2020
Cited by 1 | Viewed by 908
Abstract
Herein, the boron and nitrogen co-doped 0-dimensional graphene quantum dots (B,N-GQDs) with high quantum yield (QY) were synthesized via microwave-assisted hydrothermal method at 170 °C for 20 min using fresh passion fruit juice and boric acid as the starting materials. The 3–6 layers [...] Read more.
Herein, the boron and nitrogen co-doped 0-dimensional graphene quantum dots (B,N-GQDs) with high quantum yield (QY) were synthesized via microwave-assisted hydrothermal method at 170 °C for 20 min using fresh passion fruit juice and boric acid as the starting materials. The 3–6 layers of B,N-GQDs with mean particle size of 9 ± 1 nm were then used for ultra-sensitive and selective detection of tetracycline in aqueous and biological media. The hybridization of boron and nitrogen atoms into the GQD structures increases the intensity of electronegative, resulting in the enhancement of QY to 50 ± 1%. The B,N-GQDs show their excellent analytical performance on tetracycline determination after 2 min of reaction under an optimal condition at pH 5. The linear range of 0.04–70 µM and with limits of detection (LOD) of 1 nM in phosphate buffer saline (PBS), 1.9 nM in urine and 2.2 nM in human serum are obtained. Moreover, the high selectivity of tetracycline by B,N-GQDs over the other 23 interferences is observed. The π-π interaction and electron donor-acceptor principle play pivotal roles in enhancing the ultra-sensitivity and selectivity of B,N-GQDs toward TC detection. Moreover, the B, N-GQD based paper nanosensor exhibits an excellent analytical performance on visual detection of 0.1–30 µM TC in human serum. Results of this study clearly indicate the feasibility of synthesis of B,N-GQDs derived from passion fruit juice for ultrasensitive tetracycline detection, which can open an avenue to use natural products for the preparation of environmentally benign and biocompatible carbon nanomaterials for highly sensitive detection of drugs, antibiotics, organic compounds and biomarkers. Full article
(This article belongs to the Section Nanoelectronics, Nanosensors and Devices)
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Article
Fabrication of Carbon-Like, π-Conjugated Organic Layer on a Nano-Porous Silica Surface
Nanomaterials 2020, 10(9), 1882; https://doi.org/10.3390/nano10091882 - 20 Sep 2020
Viewed by 1000
Abstract
This paper presents a new type of black organic material-porous silica composite providing an extremely highly selective adsorption surface. This black composite was prepared by lamination on nano-sized pores with a carbon-like, π-extended structure, which can be converted via the on-site polymerization of [...] Read more.
This paper presents a new type of black organic material-porous silica composite providing an extremely highly selective adsorption surface. This black composite was prepared by lamination on nano-sized pores with a carbon-like, π-extended structure, which can be converted via the on-site polymerization of 1,5-dihydroxynaphthalene with a triazinane derivative and a thermally induced condensation reaction with denitrification. This bottom-up fabrication method on porous materials had the great advantage of maintaining the pore characteristics of a raw porous material, but also the resultant black surface exhibited an extremely high molecular-shape selectivity; for example, that for trans- and cis-stilbenes reached 14.0 with the black layer-laminated porous silica, whereas it was below 1.2 with simple hydrophobized silica. Full article
(This article belongs to the Section Synthesis, Interfaces and Nanostructures)
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Article
Plasmon-Enhanced Photothermal and Optomechanical Deformations of a Gold Nanoparticle
Nanomaterials 2020, 10(9), 1881; https://doi.org/10.3390/nano10091881 - 20 Sep 2020
Viewed by 723
Abstract
Plasmon-enhanced photothermal and optomechanical effects on deforming and reshaping a gold nanoparticle (NP) are studied theoretically. A previous paper (Wang and Ding, ACS Nano 13, 32–37, 2019) has shown that a spherical gold nanoparticle (NP) irradiated by a tightly focused laser beam can [...] Read more.
Plasmon-enhanced photothermal and optomechanical effects on deforming and reshaping a gold nanoparticle (NP) are studied theoretically. A previous paper (Wang and Ding, ACS Nano 13, 32–37, 2019) has shown that a spherical gold nanoparticle (NP) irradiated by a tightly focused laser beam can be deformed into an elongated nanorod (NR) and even chopped in half (a dimer). The mechanism is supposed to be caused by photothermal heating for softening NP associated with optical traction for follow-up deformation. In this paper, our study focuses on deformation induced by Maxwell’s stress provided by a linearly polarized Gaussian beam upon the surface of a thermal-softened NP/NR. We use an elastic model to numerically calculate deformation according to optical traction and a viscoelastic model to theoretically estimate the following creep (elongation) as temperature nears the melting point. Our results indicate that a stretching traction at the two ends of the NP/NR causes elongation and a pinching traction at the middle causes a dent. Hence, a bigger NP can be elongated and then cut into two pieces (a dimer) at the dent due to the optomechanical effect. As the continuous heating process induces premelting of NPs, a quasi-liquid layer is formed first and then an outer liquid layer is induced due to reduction of surface energy, which was predicted by previous works of molecular dynamics simulation. Subsequently, we use the Young–Laplace model to investigate the surface tension effect on the following deformation. This study may provide an insight into utilizing the photothermal effect associated with optomechanical manipulation to tailor gold nanostructures. Full article
(This article belongs to the Section Nanofabrication and Nanomanufacturing)
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Article
Single Crystalline Higher Manganese Silicide Nanowire Arrays with Outstanding Physical Properties through Double Tube Chemical Vapor Deposition
Nanomaterials 2020, 10(9), 1880; https://doi.org/10.3390/nano10091880 - 19 Sep 2020
Cited by 1 | Viewed by 830
Abstract
In this work, we report a novel and efficient silicidation method to synthesize higher manganese silicide (HMS) nanowires with interesting characterization and physical properties. High density silicon nanowire arrays fabricated by chemical etching reacted with MnCl2 precursor through a unique double tube [...] Read more.
In this work, we report a novel and efficient silicidation method to synthesize higher manganese silicide (HMS) nanowires with interesting characterization and physical properties. High density silicon nanowire arrays fabricated by chemical etching reacted with MnCl2 precursor through a unique double tube chemical vapor deposition (CVD) system, where we could enhance the vapor pressure of the precursor and provide stable Mn vapor with a sealing effect. It is crucial that the method enables the efficient formation of high quality higher manganese silicide nanowires without a change in morphology and aspect ratio during the process. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were utilized to characterize the HMS nanowires. High-resolution TEM studies confirm that the HMS nanowires were single crystalline Mn27Si47 nanowires of Nowotny Chimney Ladder crystal structures. Magnetic property measurements show that the Mn27Si47 nanowire arrays were ferromagnetic at room temperature with a Curie temperature of over 300 K, highly depending on the relationship between the direction of the applied electric field and the axial direction of the standing nanowire arrays. Field emission measurements indicate that the 20 μm long nanowires possessed a field enhancement factor of 3307. The excellent physical properties of the HMS nanowires (NWs) make them attractive choices for applications in spintronic devices and field emitters. Full article
(This article belongs to the Section Nanofabrication and Nanomanufacturing)
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Article
Printed and Flexible Microheaters Based on Carbon Nanotubes
Nanomaterials 2020, 10(9), 1879; https://doi.org/10.3390/nano10091879 - 19 Sep 2020
Viewed by 1043
Abstract
This work demonstrates a cost-effective manufacturing method of flexible and fully printed microheaters, using carbon nanotubes (CNTs) as the heating element. Two different structures with different number of CNT layers have been characterized in detail. The benchmarking has been carried out in terms [...] Read more.
This work demonstrates a cost-effective manufacturing method of flexible and fully printed microheaters, using carbon nanotubes (CNTs) as the heating element. Two different structures with different number of CNT layers have been characterized in detail. The benchmarking has been carried out in terms of maximum operating temperature, as well as nominal resistance and input power for different applied voltages. Their performances have been compared with previous reports for similar devices, fabricated with other technologies. The results have shown that the heaters presented can achieve high temperatures in a small area at lower voltages and lower input power. In particular, the fully printed heaters fabricated on a flexible substrate covering an area of 3.2 mm2 and operating at 9.5 V exhibit a maximum temperature point above 70 °C with a power consumption below 200 mW. Therefore, we have demonstrated that this technology paves the way for a cost-effective large-scale fabrication of flexible microheaters aimed to be integrated in flexible sensors. Full article
(This article belongs to the Special Issue Functional Nanomaterials for Sensor Applications)
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Perspective
Perspectives on Nickel Hydroxide Electrodes Suitable for Rechargeable Batteries: Electrolytic vs. Chemical Synthesis Routes
Nanomaterials 2020, 10(9), 1878; https://doi.org/10.3390/nano10091878 - 19 Sep 2020
Cited by 2 | Viewed by 909
Abstract
A significant amount of work on electrochemical energy storage focuses mainly on current lithium-ion systems with the key markets being portable and transportation applications. There is a great demand for storing higher capacity (mAh/g) and energy density (Wh/kg) of the electrode material for [...] Read more.
A significant amount of work on electrochemical energy storage focuses mainly on current lithium-ion systems with the key markets being portable and transportation applications. There is a great demand for storing higher capacity (mAh/g) and energy density (Wh/kg) of the electrode material for electronic and vehicle applications. However, for stationary applications, where weight is not as critical, nickel-metal hydride (Mi-MH) technologies can be considered with tolerance to deep discharge conditions. Nickel hydroxide has gained importance as it is used as the positive electrode in nickel-metal hydride and other rechargeable batteries such as Ni-Fe and Ni-Cd systems. Nickel hydroxide is manufactured industrially by chemical methods under controlled conditions. However, the electrochemical route is relatively better than the chemical counterpart. In the electrochemical route, a well-regulated OH is generated at the cathode forming nickel hydroxide (Ni(OH)2) through controlling and optimizing the current density. It produces nickel hydroxide of better purity with an appropriate particle size, well-oriented morphology, structure, et cetera, and this approach is found to be environmentally friendly. The structures of the nickel hydroxide and its production technologies are presented. The mechanisms of product formation in both chemical and electrochemical preparation of nickel hydroxide have been presented along with the feasibility of producing pure nickel hydroxide in this review. An advanced Ni(OH)2-polymer embedded electrode has been reported in the literature but may not be suitable for scalable electrochemical methods. To the best of our knowledge, no such insights on the Ni(OH)2 synthesis route for battery applications has been presented in the literature. Full article
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Article
Effects of Few-Layer Graphene on the Sexual Reproduction of Seed Plants: An In Vivo Study with Cucurbita pepo L.
Nanomaterials 2020, 10(9), 1877; https://doi.org/10.3390/nano10091877 - 19 Sep 2020
Viewed by 1132
Abstract
Products containing graphene-related materials (GRMs) are becoming quite common, raising concerns for environmental safety. GRMs have varying effects on plants, but their impact on the sexual reproduction process is largely unknown. In this study, the effects of few-layer graphene (FLG) and a similarly [...] Read more.
Products containing graphene-related materials (GRMs) are becoming quite common, raising concerns for environmental safety. GRMs have varying effects on plants, but their impact on the sexual reproduction process is largely unknown. In this study, the effects of few-layer graphene (FLG) and a similarly layered phyllosilicate, muscovite mica (MICA), were tested in vivo on the reproductive structures, i.e., pollen and stigma, of Cucurbita pepo L. ssp. pepogreyzini’ (summer squash, zucchini). Pollen was exposed to FLG or MICA, after careful physical-chemical characterization, at concentrations of 0.5 and 2 mg of nanomaterial (NM) per g of pollen for up to six hours. Following this, pollen viability was tested. Stigmas were exposed to FLG or MICA for three hours and then analyzed by environmental scanning electron microscopy to verify possible alterations to their surface. Stigmas were then hand-pollinated to verify the effects of the two NMs on pollen adhesion and in vivo pollen germination. FLG and MICA altered neither pollen viability nor the stigmatic surface. However, both NMs equivalently decreased pollen adhesion and in vivo germination compared with untreated stigmas. These effects deserve further attention as they could impact on production of fruits and seeds. Importantly, it was shown that FLG is as safe as a naturally occurring nanomaterial. Full article
(This article belongs to the Special Issue Nanotechnology in Agriculture and Food Industry)
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Article
Evaluation of the NLRP3 Inflammasome Activating Effects of a Large Panel of TiO2 Nanomaterials in Macrophages
Nanomaterials 2020, 10(9), 1876; https://doi.org/10.3390/nano10091876 - 19 Sep 2020
Cited by 3 | Viewed by 837
Abstract
TiO2 nanomaterials are among the most commonly produced and used engineered nanomaterials (NMs) in the world. There is controversy regarding their ability to induce inflammation-mediated lung injuries following inhalation exposure. Activation of the NACHT, LRR and PYD domains-containing protein 3 (NALP3) inflammasome [...] Read more.
TiO2 nanomaterials are among the most commonly produced and used engineered nanomaterials (NMs) in the world. There is controversy regarding their ability to induce inflammation-mediated lung injuries following inhalation exposure. Activation of the NACHT, LRR and PYD domains-containing protein 3 (NALP3) inflammasome and subsequent release of the cytokine interleukin (IL)-1β in pulmonary macrophages has been postulated as an essential pathway for the inflammatory and associated tissue-remodeling effects of toxic particles. Our study aim was to determine and rank the IL-1β activating properties of TiO2 NMs by comparing a large panel of different samples against each other as well as against fine TiO2, synthetic amorphous silica and crystalline silica (DQ12 quartz). Effects were evaluated in primary bone marrow derived macrophages (BMDMs) from NALP3-deficient and proficient mice as well as in the rat alveolar macrophage cell line NR8383. Our results show that specific TiO2 NMs can activate the inflammasome in macrophages albeit with a markedly lower potency than amorphous SiO2 and quartz. The heterogeneity in IL-1β release observed in our study among 19 different TiO2 NMs underscores the relevance of case-by-case evaluation of nanomaterials of similar chemical composition. Our findings also further promote the NR8383 cell line as a promising in vitro tool for the assessment of the inflammatory and inflammasome activating properties of NMs. Full article
(This article belongs to the Special Issue Toxicology and Biocompatibility of Nanomaterials)
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Article
A New Zinc Phosphate-Tellurite Glass for Magneto-Optical Applications
Nanomaterials 2020, 10(9), 1875; https://doi.org/10.3390/nano10091875 - 18 Sep 2020
Viewed by 737
Abstract
This work investigates the structural, magnetic and magneto-optical properties of a new zinc phosphate-tellurite glass belonging to the 45ZnO-10Al2O3-40P2O5-5TeO2 system. The glass was prepared by a wet method of processing the starting reagents followed [...] Read more.
This work investigates the structural, magnetic and magneto-optical properties of a new zinc phosphate-tellurite glass belonging to the 45ZnO-10Al2O3-40P2O5-5TeO2 system. The glass was prepared by a wet method of processing the starting reagents followed by suitable melting–stirring–quenching–annealing steps. Specific parameters such as density, average molecular mass, molar volume, oxygen packaging density, refractive index, molar refractivity, electronic polarizability, reflection loss, optical transmission, band gap and optical basicity have been reported together with thermal, magnetic and magneto-optical characteristics. Absorption bands appear in the blue and red visible region, while over 600 nm the glass becomes more transparent. FTIR and Raman spectra evidenced phosphate-tellurite vibration modes proving the P2O5 and TeO2 network forming role. Magnetic measurements reveal the diamagnetic character of the Te-doped glass with an additional weak ferromagnetic signal, specific to diluted ferromagnetic oxides. Positive Faraday rotation angle with monotonous decreasing value at increasing wavelength was evidenced from magneto-optical measurements. The final product is a composite material comprising of a non-crystalline vitreous phase and Te-based nanoclusters accompanied by oxygen vacancies. The metallic-like Te colloids are responsible for the dark reddish color of the glass whereas the accompanying oxygen vacancies might be responsible for the weak ferromagnetic signal persisting up to room temperature. Full article
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Article
Effect of Al2O3 Dot Patterning on CZTSSe Solar Cell Characteristics
Nanomaterials 2020, 10(9), 1874; https://doi.org/10.3390/nano10091874 - 18 Sep 2020
Viewed by 764
Abstract
In this study, a 5-nm thick Al2O3 layer was patterned onto the Mo electrode in the form of a dot to produce a local rear contact, which looked at the effects of this contact structure on Cu2ZnSn(S1-x [...] Read more.
In this study, a 5-nm thick Al2O3 layer was patterned onto the Mo electrode in the form of a dot to produce a local rear contact, which looked at the effects of this contact structure on Cu2ZnSn(S1-xSex)4 (CZTSSe) growth and solar cell devices. Mo was partially exposed through open holes having a square dot shape, and the closed-ratios of Al2O3 passivated areas were 56%, 75%, and 84%. The process of synthesizing CZTSSe is the same as that of the previous process showing 12.62% efficiency. When the 5-nm-Al2O3 dot patterning was applied to the Mo surface, we observed that the MoSSe formation was well suppressed under the area coated of 5-nm-Al2O3 film. The self-alignment phenomenon was observed in the back-contact area. CZTSSe was easily formed in the Mo-exposed area, while voids were formed near the Al2O3-coated area. The efficiency of the CZTSSe solar cell decreased when the Al2O3 passivated area increased. The exposure area and pitch of Mo, the collecting path of the hole, and the supplying path of Na seemed to be related to efficiency. Thus, it was suggested that the optimization of the Mo-exposed pattern and the additional Na supply are necessary to develop the optimum self-aligned CZTSSe light absorber. Full article
(This article belongs to the Section Energy and Catalysis)
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Article
Innovative Low-Cost Carbon/ZnO Hybrid Materials with Enhanced Photocatalytic Activity towards Organic Pollutant Dyes’ Removal
Nanomaterials 2020, 10(9), 1873; https://doi.org/10.3390/nano10091873 - 18 Sep 2020
Cited by 2 | Viewed by 811
Abstract
A new type of material based on carbon/ZnO nanostructures that possesses both adsorption and photocatalytic properties was obtained in three stages: cellulose acetate butyrate (CAB) microfiber mats prepared by the electrospinning method, ZnO nanostructures growth by dipping and hydrothermal methods, and finally thermal [...] Read more.
A new type of material based on carbon/ZnO nanostructures that possesses both adsorption and photocatalytic properties was obtained in three stages: cellulose acetate butyrate (CAB) microfiber mats prepared by the electrospinning method, ZnO nanostructures growth by dipping and hydrothermal methods, and finally thermal calcination at 600 °C in N2 for 30 min. X-ray diffraction (XRD) confirmed the structural characteristics. It was found that ZnO possesses a hexagonal wurtzite crystalline structure. The ZnO nanocrystals with star-like and nanorod shapes were evidenced by scanning electron microscopy (SEM) measurements. A significant decrease in Eg value was found for carbon/ZnO hybrid materials (2.51 eV) as compared to ZnO nanostructures (3.21 eV). The photocatalytic activity was evaluated by studying the degradation of three dyes, Methylene Blue (MB), Rhodamine B (RhB) and Congo Red (CR) under visible-light irradiation. Therefore, the maximum color removal efficiency (both adsorption and photocatalytic processes) was: 97.97% of MB (C0 = 10 mg/L), 98.34% of RhB (C0 = 5 mg/L), and 91.93% of CR (C0 = 10 mg/L). Moreover, the value of the rate constant (k) was found to be 0.29 × 10−2 min−1. The novelty of this study relies on obtaining new photocatalysts based on carbon/ZnO using cheap and accessible raw materials, and low-cost preparation techniques. Full article
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Article
Biocompatible PEO-b-PCL Nanosized Micelles as Drug Carriers: Structure and Drug–Polymer Interactions
Nanomaterials 2020, 10(9), 1872; https://doi.org/10.3390/nano10091872 - 18 Sep 2020
Cited by 2 | Viewed by 737
Abstract
We report on the preparation of drug nanocarriers by encapsulating losartan potassium (LSR) into amphiphilic block copolymer micelles, utilizing the biocompatible/biodegradable poly(ethylene oxide)-b-poly(ε-caprolactone) (PEO-b-PCL) diblock copolymer. The PEO-b-PCL micelles and LSR-loaded PEO-b-PCL nanocarriers were prepared by organic solvent evaporation method (OSEM). Light scattering [...] Read more.
We report on the preparation of drug nanocarriers by encapsulating losartan potassium (LSR) into amphiphilic block copolymer micelles, utilizing the biocompatible/biodegradable poly(ethylene oxide)-b-poly(ε-caprolactone) (PEO-b-PCL) diblock copolymer. The PEO-b-PCL micelles and LSR-loaded PEO-b-PCL nanocarriers were prepared by organic solvent evaporation method (OSEM). Light scattering and nuclear magnetic resonance (NMR) provide information on micelle structure and polymer–drug interactions. According to dynamic light scattering (DLS) analysis, the PEO-b-PCL micelles and LSR-loaded PEO-b-PCL nanocarriers formed nanostructures in the range of 17–26 nm in aqueous milieu. Attenuated total reflection Fourier transform infrared (ATR-FTIR) and ultraviolet-visible (UV-Vis) measurements confirmed the presence of LSR in the polymeric drug solutions. NMR results proved the successful encapsulation of LSR into the PEO-b-PCL micelles by analyzing the drug–micelles intermolecular interactions. Specifically, 2D-NOESY experiments clearly evidenced the intermolecular interactions between the biphenyl ring and butyl chain of LSR structure with the methylene signals of PCL. Additionally, NMR studies as a function of temperature demonstrated an unexpected, enhanced proton mobility of the PEO-b-PCL micellar core in D2O solutions, probably caused by the melting of the PCL hydrophobic core. Full article
(This article belongs to the Special Issue Nanodispersions Based on Biocompatibility)
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Review
Photoactive Tungsten-Oxide Nanomaterials for Water-Splitting
Nanomaterials 2020, 10(9), 1871; https://doi.org/10.3390/nano10091871 - 18 Sep 2020
Cited by 5 | Viewed by 987
Abstract
This review focuses on tungsten oxide (WO3) and its nanocomposites as photoactive nanomaterials for photoelectrochemical cell (PEC) applications since it possesses exceptional properties such as photostability, high electron mobility (~12 cm2 V−1 s−1) and a long hole-diffusion [...] Read more.
This review focuses on tungsten oxide (WO3) and its nanocomposites as photoactive nanomaterials for photoelectrochemical cell (PEC) applications since it possesses exceptional properties such as photostability, high electron mobility (~12 cm2 V−1 s−1) and a long hole-diffusion length (~150 nm). Although WO3 has demonstrated oxygen-evolution capability in PEC, further increase of its PEC efficiency is limited by high recombination rate of photogenerated electron/hole carriers and slow charge transfer at the liquid–solid interface. To further increase the PEC efficiency of the WO3 photocatalyst, designing WO3 nanocomposites via surface–interface engineering and doping would be a great strategy to enhance the PEC performance via improving charge separation. This review starts with the basic principle of water-splitting and physical chemistry properties of WO3, that extends to various strategies to produce binary/ternary nanocomposites for PEC, particulate photocatalysts, Z-schemes and tandem-cell applications. The effect of PEC crystalline structure and nanomorphologies on efficiency are included. For both binary and ternary WO3 nanocomposite systems, the PEC performance under different conditions—including synthesis approaches, various electrolytes, morphologies and applied bias—are summarized. At the end of the review, a conclusion and outlook section concluded the WO3 photocatalyst-based system with an overview of WO3 and their nanocomposites for photocatalytic applications and provided the readers with potential research directions. Full article
(This article belongs to the Special Issue Photoactive Nanomaterials)
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Article
Protective Spinel Coating for Li1.17Ni0.17Mn0.50Co0.17O2 Cathode for Li-Ion Batteries through Single-Source Precursor Approach
Nanomaterials 2020, 10(9), 1870; https://doi.org/10.3390/nano10091870 - 18 Sep 2020
Cited by 3 | Viewed by 852
Abstract
The Li1.17Ni0.17Mn0.50Co0.17O2 Li-rich NMC positive electrode (cathode) for lithium-ion batteries has been coated with nanocrystals of the LiMn1.5Co0.5O4 high-voltage spinel cathode material. The coating was applied through a single-source [...] Read more.
The Li1.17Ni0.17Mn0.50Co0.17O2 Li-rich NMC positive electrode (cathode) for lithium-ion batteries has been coated with nanocrystals of the LiMn1.5Co0.5O4 high-voltage spinel cathode material. The coating was applied through a single-source precursor approach by a deposition of the molecular precursor LiMn1.5Co0.5(thd)5 (thd = 2,2,6,6-tetramethyl-3,5-heptanedionate) dissolved in diethyl ether, followed by thermal decomposition at 400 °C inair resulting in a chemically homogeneous cubic spinel. The structure and chemical composition of the coatings, deposited on the model SiO2 spheres and Li-rich NMC crystallites, were analyzed using powder X-ray diffraction, electron diffraction, high angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), and energy-dispersive X-ray (EDX) mapping. The coated material containing 12 wt.% of spinel demonstrates a significantly improved first cycle Coulombic efficiency of 92% with a high first cycle discharge capacity of 290 mAhg−1. The coating also improves the capacity and voltage retention monitored over 25 galvanostatic charge–discharge cycles, although a complete suppression of the capacity and voltage fade is not achieved. Full article
(This article belongs to the Section Energy and Catalysis)
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Article
Green Synthesis and Characterization of Gold Nanoparticles Using Lignin Nanoparticles
Nanomaterials 2020, 10(9), 1869; https://doi.org/10.3390/nano10091869 - 18 Sep 2020
Cited by 3 | Viewed by 760
Abstract
With the development of nanotechnology, gold nanoparticles (Au NPs) have attracted enormous attention due to their special properties. The green synthesis of Au NPs from lignin would inspire the utilization of lignin and its related functional materials. In this study, a rapid preparation [...] Read more.
With the development of nanotechnology, gold nanoparticles (Au NPs) have attracted enormous attention due to their special properties. The green synthesis of Au NPs from lignin would inspire the utilization of lignin and its related functional materials. In this study, a rapid preparation process of Au NPs was investigated by utilizing lignin nanoparticles (LNPs) under room temperature without chemical addition. The LNPs acted as a reducing agent, stabilizing agent, and template for the preparation of [email protected] The obtained [email protected] were characterized by UV-Vis spectrum, Transmission Electron Microscope (TEM), and X-ray photoelectron spectroscopy (XPS). The possible mechanism was illustrated by Fourier Transform Infrared Spectroscopy (FT-IR), 31P, XPS, and UV analyses. The abundant hydroxyl groups (24.96 mmol/g) favored the preparation of Au NPs. Au NPs diameters of 10–30 nm were well dispersed in the LNPs. The optimal reaction conditions were a ratio of 10 mg of LNPs to 0.05 mmol HAuCl4, room temperature, and a reaction time of 30 min. The [email protected] exhibited excellent stability in the suspension for more than seven days. The reduction process could be related to the disruption of side chains of lignin, hydroxyl group oxidation, and hydroquinones and quinones from the comproportionation reaction. The [email protected] would open a door for the design of Au NP/lignin-derived novel functional materials. Full article
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Article
Silver Nanoparticles Alter Cell Viability Ex Vivo and in Vitro and Induce Proinflammatory Effects in Human Lung Fibroblasts
Nanomaterials 2020, 10(9), 1868; https://doi.org/10.3390/nano10091868 - 18 Sep 2020
Cited by 2 | Viewed by 685
Abstract
Silver nanoparticles (AgNPs) are commonly used in commercial and medical applications. However, AgNPs may induce toxicity, extracellular matrix (ECM) changes and inflammatory responses. Fibroblasts are key players in remodeling processes and major producers of the ECM. The aims of this study were to [...] Read more.
Silver nanoparticles (AgNPs) are commonly used in commercial and medical applications. However, AgNPs may induce toxicity, extracellular matrix (ECM) changes and inflammatory responses. Fibroblasts are key players in remodeling processes and major producers of the ECM. The aims of this study were to explore the effect of AgNPs on cell viability, both ex vivo in murine precision cut lung slices (PCLS) and in vitro in human lung fibroblasts (HFL-1), and immunomodulatory responses in fibroblasts. PCLS and HFL-1 were exposed to AgNPs with different sizes, 10 nm and 75 nm, at concentrations 2 µg/mL and 10 μg/mL. Changes in synthesis of ECM proteins, growth factors and cytokines were analyzed in HFL-1. Ag10 and Ag75 affected cell viability, with significantly reduced metabolic activities at 10 μg/mL in both PCLS and HFL-1 after 48 h. AgNPs significantly increased procollagen I synthesis and release of IL-8, prostaglandin E2, RANTES and eotaxin, whereas reduced IL-6 release was observed in HFL-1 after 72 h. Our data indicate toxic effects of AgNP exposure on cell viability ex vivo and in vitro with altered procollagen and proinflammatory cytokine secretion in fibroblasts over time. Hence, careful characterizations of AgNPs are of importance, and future studies should include timepoints beyond 24 h. Full article
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Article
Developing a Highly Stable Carlina acaulis Essential Oil Nanoemulsion for Managing Lobesia botrana
Nanomaterials 2020, 10(9), 1867; https://doi.org/10.3390/nano10091867 - 18 Sep 2020
Cited by 6 | Viewed by 1014
Abstract
The growing interest in the development of green pest management strategies is leading to the exploitation of essential oils (EOs) as promising botanical pesticides. In this respect, nanotechnology could efficiently support the use of EOs through their encapsulation into stable nanoformulations, such as [...] Read more.
The growing interest in the development of green pest management strategies is leading to the exploitation of essential oils (EOs) as promising botanical pesticides. In this respect, nanotechnology could efficiently support the use of EOs through their encapsulation into stable nanoformulations, such as nanoemulsions (NEs), to improve their stability and efficacy. This technology assures the improvement of the chemical stability, hydrophilicity, and environmental persistence of EOs, giving an added value for the fabrication of natural insecticides effective against a wide spectrum of insect vectors and pests of public and agronomical importance. Carlina acaulis (Asteraceae) root EO has been recently proposed as a promising ingredient of a new generation of botanical insecticides. In the present study, a highly stable C. acaulis-based NE was developed. Interestingly, such a nanosystem was able to encapsulate 6% (w/w) of C. acaulis EO, showing a mean diameter of around 140 nm and a SOR (surfactant-to-oil ratio) of 0.6. Its stability was evaluated in a storage period of six months and corroborated by an accelerated stability study. Therefore, the C. acaulis EO and C. acaulis-based NE were evaluated for their toxicity against 1st instar larvae of the European grapevine moth (EGVM), Lobesia botrana (Denis & Schiffermüller, 1775) (Lepidoptera: Tortricidae), a major vineyard pest. The chemical composition of C. acaulis EO was investigated by gas chromatography–mass spectrometry (GC–MS) revealing carlina oxide, a polyacetylene, as the main constituent. In toxicity assays, both the C. acaulis EO and the C. acaulis-based NE were highly toxic to L. botrana larvae, with LC50 values of 7.299 and 9.044 µL/mL for C. acaulis EO and NE, respectively. The C. acaulis-based NE represents a promising option to develop highly stable botanical insecticides for pest management. To date, this study represents the first evidence about the insecticidal toxicity of EOs and EO-based NEs against this major grapevine pest. Full article
(This article belongs to the Special Issue Green Synthesis of Nanomaterials and Their Biological Applications)
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Article
Plasmon-Assisted Direction- and Polarization-Sensitive Organic Thin-Film Detector
Nanomaterials 2020, 10(9), 1866; https://doi.org/10.3390/nano10091866 - 17 Sep 2020
Cited by 1 | Viewed by 798
Abstract
Utilizing Bragg surface plasmon polaritons (SPPs) on metal nanostructures for the use in optical devices has been intensively investigated in recent years. Here, we demonstrate the integration of nanostructured metal electrodes into an ITO-free thin film bulk heterojunction organic solar cell, by direct [...] Read more.
Utilizing Bragg surface plasmon polaritons (SPPs) on metal nanostructures for the use in optical devices has been intensively investigated in recent years. Here, we demonstrate the integration of nanostructured metal electrodes into an ITO-free thin film bulk heterojunction organic solar cell, by direct fabrication on a nanoimprinted substrate. The nanostructured device shows interesting optical and electrical behavior, depending on angle and polarization of incidence and the side of excitation. Remarkably, for incidence through the top electrode, a dependency on linear polarization and angle of incidence can be observed. We show that these peculiar characteristics can be attributed to the excitation of dispersive and non-dispersive Bragg SPPs on the metal–dielectric interface on the top electrode and compare it with incidence through the bottom electrode. Furthermore, the optical and electrical response can be controlled by the organic photoactive material, the nanostructures, the materials used for the electrodes and the epoxy encapsulation. Our device can be used as a detector, which generates a direct electrical readout and therefore enables the measuring of the angle of incidence of up to 60° or the linear polarization state of light, in a spectral region, which is determined by the active material. Our results could furthermore lead to novel organic Bragg SPP-based sensor for a number of applications. Full article
(This article belongs to the Special Issue Nanoimprint Lithography Technology and Applications)
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