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Nanomaterials, Volume 8, Issue 5 (May 2018)

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Editorial

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Open AccessEditorial ZnO- and TiO2-Based Nanostructures
Nanomaterials 2018, 8(5), 325; https://doi.org/10.3390/nano8050325
Received: 8 May 2018 / Revised: 8 May 2018 / Accepted: 10 May 2018 / Published: 14 May 2018
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Abstract
Transition-metal oxide (TMO) nanostructures are the focus of current research efforts in nanotechnology since they are the most common minerals on Earth, and also thanks to their special shapes, compositions, and chemical and physical properties.[...] Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures)
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Research

Jump to: Editorial, Review, Other

Open AccessFeature PaperArticle Cationic Liposomes Carrying siRNA: Impact of Lipid Composition on Physicochemical Properties, Cytotoxicity and Endosomal Escape
Nanomaterials 2018, 8(5), 270; https://doi.org/10.3390/nano8050270
Received: 13 April 2018 / Revised: 18 April 2018 / Accepted: 21 April 2018 / Published: 24 April 2018
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Abstract
In recent year, cationic liposomes have gained a lot of attention for siRNA delivery. Despite this, intracellular barriers as endosomal escape and cytosolic delivery of siRNA still represent a challeng, as well as the cytotoxicity due to cationic lipids. To address these issues,
[...] Read more.
In recent year, cationic liposomes have gained a lot of attention for siRNA delivery. Despite this, intracellular barriers as endosomal escape and cytosolic delivery of siRNA still represent a challeng, as well as the cytotoxicity due to cationic lipids. To address these issues, we developed four liposomal formulations, composed of two different cationic lipids (DOTAP and DC-Cholesterol) and different ratio of co-lipids (cholesterol and DOPE). The objective is to dissect these impacts on siRNA efficacy and cytotoxicity. Liposomes were complexed to siRNA at six different N/P molar ratios, physico-chemical properties were characterized, and consequently, N/P 2.5, 5 and 10 were selected for in vitro experiments. We have shown that cytotoxicity is influenced by the N/P ratio, the concentration of cationic lipid, as well as the nature of the cationic lipid. For instance, cell viability decreased by 70% with liposomes composed of DOTAP/Cholesterol/DOPE 1/0.75/0.5 at a N/P ratio 10, whereas the same formulation at a N/P ratio of 2.5 was safe. Interestingly, we have observed differences in terms of mRNA knock-down efficiency, whereas the transfection rate was quite similar for each formulation. Liposomes containing 50% of DOPE induced a mRNA silencing of around 80%. This study allowed us to highlight crucial parameters in order to develop lipoplexes which are safe, and which induce an efficient intracytoplasmic release of siRNA. Full article
(This article belongs to the Special Issue Pharmaceutical Nanotechnology)
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Open AccessArticle Fabrication and Adsorption Behavior of Magnesium Silicate Hydrate Nanoparticles towards Methylene Blue
Nanomaterials 2018, 8(5), 271; https://doi.org/10.3390/nano8050271
Received: 13 March 2018 / Revised: 19 April 2018 / Accepted: 20 April 2018 / Published: 24 April 2018
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Abstract
Magnesium silicate as a high-performance adsorption material has attracted increasing attention for the removal of organic dye pollution. Here, we prepared a series of magnesium silicate hydrates (MSH) in a hydrothermal route, and carefully investigated the corresponding adsorption behavior towards methylene blue (MB)
[...] Read more.
Magnesium silicate as a high-performance adsorption material has attracted increasing attention for the removal of organic dye pollution. Here, we prepared a series of magnesium silicate hydrates (MSH) in a hydrothermal route, and carefully investigated the corresponding adsorption behavior towards methylene blue (MB) as well as the effect of surface charge on adsorption capacity. The results show that surface charge plays a key role in the adsorption performance of MSH for MB, a negative surface charge density follows the increase of Si/Mg feeding ratio from 1.00 to 1.75, and furthermore the higher negative charge favors the improvement of the adsorption capacity. Among four investigated samples (MSH = 1.00, 1.25, 1.50, and 1.75), MSH-1.75 has the highest negative surface charge and shows the largest adsorption capacity for MB. For example, the equilibrium adsorption quantity is 307 mg·g−1 for MSH-1.75, which is 35% higher than that of 227 mg·g−1 for MSH-1.00. Besides, for MSH-1.75, the as-prepared sample with negative charge exhibits ca. 36% higher adsorption quantity compared to the sample at the zero point of charge (pHZPC). Furthermore, magnesium silicate hydrate material with Si/Mg feeding ratio = 1.75 demonstrates the promising removal efficiency of beyond 98% for methylene blue in 10 min, and the maximum adsorption capacity of 374 mg·g−1 calculated from the Langmuir isotherm model. Full article
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Open AccessArticle Effect of Laminating Pressure on Polymeric Multilayer Nanofibrous Membranes for Liquid Filtration
Nanomaterials 2018, 8(5), 272; https://doi.org/10.3390/nano8050272
Received: 8 February 2018 / Revised: 7 March 2018 / Accepted: 23 April 2018 / Published: 24 April 2018
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Abstract
In the new century, electrospun nanofibrous webs are widely employed in various applications due to their specific surface area and porous structure with narrow pore size. The mechanical properties have a major influence on the applications of nanofiber webs. Lamination technology is an
[...] Read more.
In the new century, electrospun nanofibrous webs are widely employed in various applications due to their specific surface area and porous structure with narrow pore size. The mechanical properties have a major influence on the applications of nanofiber webs. Lamination technology is an important method for improving the mechanical strength of nanofiber webs. In this study, the influence of laminating pressure on the properties of polyacrylonitrile (PAN) and polyvinylidene fluoride (PVDF) nanofibers/laminate was investigated. Heat-press lamination was carried out at three different pressures, and the surface morphologies of the multilayer nanofibrous membranes were observed under an optical microscope. In addition, air permeability, water filtration, and contact angle experiments were performed to examine the effect of laminating pressure on the breathability, water permeability and surface wettability of multilayer nanofibrous membranes. A bursting strength test was developed and applied to measure the maximum bursting pressure of the nanofibers from the laminated surface. A water filtration test was performed using a cross-flow unit. Based on the results of the tests, the optimum laminating pressure was determined for both PAN and PVDF multilayer nanofibrous membranes to prepare suitable microfilters for liquid filtration. Full article
(This article belongs to the Special Issue Design and Development of Nanostructured Thin Films)
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Open AccessArticle Cucurbit[n]uril (n = 6, 7) Based Carbon-Gold Hybrids with Peroxidase-Like Activity
Nanomaterials 2018, 8(5), 273; https://doi.org/10.3390/nano8050273
Received: 4 April 2018 / Revised: 17 April 2018 / Accepted: 20 April 2018 / Published: 24 April 2018
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Abstract
Despite the combination of molecular recognition and local electric field enhancement endowing cucurbit[n]uril-capped metallic nanoparticles, indicating great potential in a variety of areas, prior work has paid little attention to carbonizing cucurbit[n]uril on the surface of gold nanoparticles, which
[...] Read more.
Despite the combination of molecular recognition and local electric field enhancement endowing cucurbit[n]uril-capped metallic nanoparticles, indicating great potential in a variety of areas, prior work has paid little attention to carbonizing cucurbit[n]uril on the surface of gold nanoparticles, which may propose new carbon-gold hybrid materials with interesting applications. In this work, we developed a simple and cost-effective method to prepare carbon-gold hybrids by carbonizing cucurbit[n]uril modified gold nanoparticles. The as-prepared cucurbit[n]uril based carbon and carbon-gold hybrid materials have shown to possess peroxidase-like activity. All cucurbit[n]uril based nanomaterials exhibited high catalytic activity over a pH range 2–6 and more tolerant to high temperature (up to 60 °C) when compared to natural horseradish peroxidase. Full article
(This article belongs to the Special Issue Supramolecular Nano-architectures)
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Open AccessArticle Self-Catalyzed CdTe Wires
Nanomaterials 2018, 8(5), 274; https://doi.org/10.3390/nano8050274
Received: 23 March 2018 / Revised: 20 April 2018 / Accepted: 23 April 2018 / Published: 25 April 2018
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Abstract
CdTe wires have been fabricated via a catalyst free method using the industrially scalable physical vapor deposition technique close space sublimation. Wire growth was shown to be highly dependent on surface roughness and deposition pressure, with only low roughness surfaces being capable of
[...] Read more.
CdTe wires have been fabricated via a catalyst free method using the industrially scalable physical vapor deposition technique close space sublimation. Wire growth was shown to be highly dependent on surface roughness and deposition pressure, with only low roughness surfaces being capable of producing wires. Growth of wires is highly (111) oriented and is inferred to occur via a vapor-solid-solid growth mechanism, wherein a CdTe seed particle acts to template the growth. Such seed particles are visible as wire caps and have been characterized via energy dispersive X-ray analysis to establish they are single phase CdTe, hence validating the self-catalysation route. Cathodoluminescence analysis demonstrates that CdTe wires exhibited a much lower level of recombination when compared to a planar CdTe film, which is highly beneficial for semiconductor applications. Full article
(This article belongs to the Special Issue Design and Development of Nanostructured Thin Films)
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Open AccessArticle Magnesium and Nitrogen Co-Doped Mesoporous Carbon with Enhanced Microporosity for CO2 Adsorption
Nanomaterials 2018, 8(5), 275; https://doi.org/10.3390/nano8050275
Received: 29 March 2018 / Revised: 20 April 2018 / Accepted: 23 April 2018 / Published: 25 April 2018
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Abstract
Mesoporous carbons (MC) have attracted a tremendous amount of interest due to their efficient molecular transport properties. However, the limited number of active sites and low microporosity generally impede their use for practical applications. Herein, we have fabricated Mg and N co-doped mesoporous
[...] Read more.
Mesoporous carbons (MC) have attracted a tremendous amount of interest due to their efficient molecular transport properties. However, the limited number of active sites and low microporosity generally impede their use for practical applications. Herein, we have fabricated Mg and N co-doped mesoporous carbon (Mg-NMC) with high microporosity via one-pot synthetic route followed by further steam activation. In comparison with the parent N-doped mesoporous carbon, Mg-NMC shows partially ordered mesostructure and improved CO2 adsorption capacity attributed to the introduction of basic site after Mg doping. Upon further steam activation, the microporosity is enhanced to 37.3%, while the CO2 adsorption capacity is also increased by 70.4% at 273 K and 1.0 bar. Full article
(This article belongs to the Special Issue Preparation and Application of Hybrid Nanomaterials)
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Open AccessArticle Enhanced Photocatalytic Activity of {110}-Faceted TiO2 Rutile Nanorods in the Photodegradation of Hazardous Pharmaceuticals
Nanomaterials 2018, 8(5), 276; https://doi.org/10.3390/nano8050276
Received: 3 April 2018 / Revised: 19 April 2018 / Accepted: 20 April 2018 / Published: 25 April 2018
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Abstract
Rutile TiO2 with highly active facets has attracted much attention owing to its enhanced activity during the photocatalytic degradation of pollutants such as pharmaceuticals in wastewater. However, it is difficult to obtain by controlling the synthetic conditions. This paper reports a simple
[...] Read more.
Rutile TiO2 with highly active facets has attracted much attention owing to its enhanced activity during the photocatalytic degradation of pollutants such as pharmaceuticals in wastewater. However, it is difficult to obtain by controlling the synthetic conditions. This paper reports a simple hydrothermal synthesis of rutile TiO2 nanorods with highly exposed {110} facets. The obtained rutile was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), and Raman spectroscopy. The main contribution to the photocatalytic activity comes from rutile nanorods with highly dominant active {110} facets, which were studied in the photodegradation of reactive cinnamic acid and more recalcitrant ibuprofen. The contribution of active species was also investigated. The present work further confirmed the hydrothermal synthesis route for controlling the preparation of highly crystalline and active rutile nanocrystals. Full article
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Open AccessArticle A Sensitive Gold Nanoplasmonic SERS Quantitative Analysis Method for Sulfate in Serum Using Fullerene as Catalyst
Nanomaterials 2018, 8(5), 277; https://doi.org/10.3390/nano8050277
Received: 23 February 2018 / Revised: 25 April 2018 / Accepted: 25 April 2018 / Published: 26 April 2018
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Abstract
Fullerene exhibited strong catalysis of the redox reaction between HAuCl4 and trisodium citrate to form gold nanoplasmon with a strong surface-enhanced Raman scattering (SERS) effect at 1615 cm−1 in the presence of Vitoria blue B molecule probes. When fullerene increased, the
[...] Read more.
Fullerene exhibited strong catalysis of the redox reaction between HAuCl4 and trisodium citrate to form gold nanoplasmon with a strong surface-enhanced Raman scattering (SERS) effect at 1615 cm−1 in the presence of Vitoria blue B molecule probes. When fullerene increased, the SERS peak enhanced linearly due to formation of more AuNPs as substrate. Upon addition of Ba2+, Ba2+ ions adsorb on the fullerene surface to inhibit the catalysis of fullerene that caused the SERS peak decreasing. Analyte SO42− combined with Ba2+ to form stable BaSO4 precipitate to release free fullerene that the catalysis recovered, and the SERS intensity increased linearly. Thus, a new SERS quantitative analysis method was established for the detection of sulfate in serum samples, with a linear range of 0.03–3.4 μM. Full article
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Open AccessArticle Characterization of Silver Nanomaterials Derived from Marine Streptomyces sp. Al-Dhabi-87 and Its In Vitro Application against Multidrug Resistant and Extended-Spectrum Beta-Lactamase Clinical Pathogens
Nanomaterials 2018, 8(5), 279; https://doi.org/10.3390/nano8050279
Received: 13 March 2018 / Revised: 19 April 2018 / Accepted: 20 April 2018 / Published: 26 April 2018
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Abstract
A novel antagonistic marine Streptomyces sp. Al-Dhabi-87 that was recovered from the Gulf region of Saudi Arabia was used to synthesize silver nanoparticles (NP) from the culture free extract. The produced NP were confirmed by UV-visible spectroscopy (UV-Vis), high-resolution scanning electron microscope (HRSEM),
[...] Read more.
A novel antagonistic marine Streptomyces sp. Al-Dhabi-87 that was recovered from the Gulf region of Saudi Arabia was used to synthesize silver nanoparticles (NP) from the culture free extract. The produced NP were confirmed by UV-visible spectroscopy (UV-Vis), high-resolution scanning electron microscope (HRSEM), transmission electron microscope (TEM), Fourier-transform infrared spectroscopy (FTIR), Energy Dispersive Spectroscopy (EDAX), and X-ray Powder Diffraction (XRD), and broth micro dilution techniques were employed for the determination of minimum inhibitory concentrations (MIC) values. The synthesized NP was authenticated by alterations in color and wavelength scanning. HRSEM and TEM analysis confirmed that the size of the NP ranged from 10 to 17 nm and that it was spherical in shape. In addition, the FTIR spectrum revealed a variation in the band values from 500 to 3300 cm−1 respectively. Rietveld refinement analysis of the XRD data confirmed the size of the NP, which coincided with the results of the TEM analysis. In addition, the Riveted refinement analysis supported the TEM data. The NP documented significant activity against the wound infection microbial strains, such as Enterococcus faecalis, Staphylococcus epidermidis, and Staphylococcus aureus. Gram negative bacteria, such as Pseudomonas aeruginosa, Klebsiella pneumonia, and Escherichia coli revealed MIC values of 0.039, 0.078, and 0.152 mg/mL, respectively. The promising activity of NP towards extended-spectrum beta-lactamases E.coli, drug resistant Acinetobacter baumannii, and multidrug resistant S. aureus (at 0.018, 0.039, and 0.039 mg/mL, respectively) was advantageous. Overall, NP that were obtained from the novel Streptomyces sp. Al-Dhabi-87, with its promising antimicrobial activity towards the drug resistant pathogens, would be useful for healing infectious diseases. Full article
(This article belongs to the Special Issue Antibacterial Activity of Nanomaterials)
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Open AccessArticle In Situ Formation of AgCo Stabilized on Graphitic Carbon Nitride and Concomitant Hydrolysis of Ammonia Borane to Hydrogen
Nanomaterials 2018, 8(5), 280; https://doi.org/10.3390/nano8050280
Received: 29 March 2018 / Revised: 20 April 2018 / Accepted: 23 April 2018 / Published: 26 April 2018
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Abstract
The development of highly-efficient heterogeneous supported catalysts for catalytic hydrolysis of ammonia borane to yield hydrogen is of significant importance considering the versatile usages of hydrogen. Herein, we reported the in situ synthesis of AgCo bimetallic nanoparticles supported on g-C3N4
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The development of highly-efficient heterogeneous supported catalysts for catalytic hydrolysis of ammonia borane to yield hydrogen is of significant importance considering the versatile usages of hydrogen. Herein, we reported the in situ synthesis of AgCo bimetallic nanoparticles supported on g-C3N4 and concomitant hydrolysis of ammonia borane for hydrogen evolution at room temperature. The as-synthesized Ag0.1Co0.9/g-C3N4 catalysts displayed the highest turnover frequency (TOF) value of 249.02 mol H2·(molAg·min)−1 for hydrogen evolution from the hydrolysis of ammonia borane, which was higher than many other reported values. Furthermore, the Ag0.1Co0.9/g-C3N4 catalyst could be recycled during five consecutive runs. The study proves that Ag0.1Co0.9/g-C3N4 is a potential catalytic material toward the hydrolysis of ammonia borane for hydrogen production. Full article
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Open AccessArticle Electronic and Magnetic Properties of Ni-Doped Zinc-Blende ZnO: A First-Principles Study
Nanomaterials 2018, 8(5), 281; https://doi.org/10.3390/nano8050281
Received: 11 March 2018 / Revised: 23 April 2018 / Accepted: 24 April 2018 / Published: 26 April 2018
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Abstract
The electronic structure, band structure, density of state, and magnetic properties of Ni-doped zinc-blende (ZB) ZnO are studied by using the first-principles method based on the spin-polarized density-functional theory. The calculated results show that Ni atoms can induce a stable ferromagnetic (FM) ground
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The electronic structure, band structure, density of state, and magnetic properties of Ni-doped zinc-blende (ZB) ZnO are studied by using the first-principles method based on the spin-polarized density-functional theory. The calculated results show that Ni atoms can induce a stable ferromagnetic (FM) ground state in Ni-doped ZB ZnO. The magnetic moments mainly originate from the unpaired Ni 3d orbitals, and the O 2p orbitals contribute a little to the magnetic moments. The magnetic moment of a supercell including a single Ni atom is 0.79 μB. The electronic structure shows that Ni-doped ZB ZnO is a half-metallic FM material. The strong spin-orbit coupling appears near the Fermi level and shows obvious asymmetry for spin-up and spin-down density of state, which indicates a significant hybrid effects from the Ni 3d and O 2p states. However, the coupling of the anti-ferromagnetic (AFM) state show metallic characteristic, the spin-up and spin-down energy levels pass through the Fermi surface. The magnetic moment of a single Ni atom is 0.74 μB. Moreover, the results show that the Ni 3d and O 2p states have a strong p-d hybridization effect near the Fermi level and obtain a high stability. The above theoretical results demonstrate that Ni-doped zinc blende ZnO can be considered as a potential half-metal FM material and dilute magnetic semiconductors. Full article
(This article belongs to the Special Issue Ferromagnetic and Magnetic Properties of Nanostructures)
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Open AccessArticle Novel Gold Dendritic Nanoforests Combined with Titanium Nitride for Visible-Light-Enhanced Chemical Degradation
Nanomaterials 2018, 8(5), 282; https://doi.org/10.3390/nano8050282
Received: 14 February 2018 / Revised: 23 April 2018 / Accepted: 24 April 2018 / Published: 26 April 2018
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Abstract
In this study, gold dendritic nanoforests (Au DNFs)-titanium nitride (TiN) composite was firstly proposed for visible-light photodegradation of pollutants. A high-power impulse magnetron sputtering system was used to coat TiN films on silicon wafers, and a fluoride-assisted galvanic replacement reaction was applied to
[...] Read more.
In this study, gold dendritic nanoforests (Au DNFs)-titanium nitride (TiN) composite was firstly proposed for visible-light photodegradation of pollutants. A high-power impulse magnetron sputtering system was used to coat TiN films on silicon wafers, and a fluoride-assisted galvanic replacement reaction was applied to deposit Au DNFs on TiN/Si substrates. Scanning electron microscope images and X-ray diffraction patterns of TiN/Si, Au DNFs/Si, and Au DNFs/TiN/Si samples verified that this synthesis process was accurately controlled. The average reflectance of Au DNFs/Si and Au DNFs/TiN/Si considerably declined to approximately 10%, because the broadband localized surface plasmon resonances of Au DNFs cause broadband absorbance and low reflectance. In photocatalytic performance, 90.66 ± 1.41% 4-nitrophenol was successfully degraded in 180 min by Au DNFs/TiN/Si under visible-light irradiation. Therefore, Au DNFs/TiN/Si has the chance to be a visible-light photocatalyst for photodegradation of pollutants. Full article
(This article belongs to the Special Issue Nanoporous Gold and Other Related Materials)
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Open AccessArticle Anti-EGFR Indocyanine Green-Mitomycin C-Loaded Perfluorocarbon Double Nanoemulsion: A Novel Nanostructure for Targeted Photochemotherapy of Bladder Cancer Cells
Nanomaterials 2018, 8(5), 283; https://doi.org/10.3390/nano8050283
Received: 8 March 2018 / Revised: 9 April 2018 / Accepted: 25 April 2018 / Published: 26 April 2018
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Abstract
The use of phototherapy as an adjuvant bladder cancer treatment has long been considered, but its application has been severely hampered due to a lack of tumor specificity, unpredicted cytotoxicity, and insufficient anticancer efficacy. In this study, we aim to manufacture anti-EGFR indocyanine
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The use of phototherapy as an adjuvant bladder cancer treatment has long been considered, but its application has been severely hampered due to a lack of tumor specificity, unpredicted cytotoxicity, and insufficient anticancer efficacy. In this study, we aim to manufacture anti-EGFR indocyanine green (ICG) mitomycin C (MMC) encapsulated perfluorocarbon double nanoemulsions (EIMPDNEs), and explore their photochemotherapeutic efficacy on EGFR-expressing bladder cancer cells in vitro. The EIMPDNEs were manufactured using a double emulsification technique followed by antibody conjugation on the particles’ surfaces. The EIMPDNE were 257 ± 19.4 nm in size, with a surface charge of −12.3 ± 2.33 mV. The EGFR targetability of the EIMPNDE was confirmed by its enhanced binding efficiency to T24 cells when compared with the performance of nanodroplets without EGFR conjugation (p < 0.05). In comparison with freely dissolved ICG, the EIMPDNEs with equal ICG content conferred an improved thermal stability to the encapsulated ICG, and were able to provide a comparable hyperthermia effect and significantly enhanced the production of singlet oxygen under 808 nm near infrared (NIR) exposure with an intensity of 6 W cm−2 for 5 min (p < 0.05). Based on viability analyses, our data showed that the EIMPDNEs were effective in bladder cancer cell eradication upon NIR exposure (808 nm; 6 W cm−2), and the resulting cell death rate was even higher than that caused by a five-fold higher amount of entrapped MMC alone. With the merits of improved ICG stability, EGFR binding specificity, and effective cancer cell eradication, the EIMPDNEs exhibit potential for use in EGFR-expressing bladder cancer therapy with lower chemotoxicity. Full article
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Open AccessArticle One-Dimensional Porous Silicon Nanowires with Large Surface Area for Fast Charge–Discharge Lithium-Ion Batteries
Nanomaterials 2018, 8(5), 285; https://doi.org/10.3390/nano8050285
Received: 10 April 2018 / Revised: 24 April 2018 / Accepted: 25 April 2018 / Published: 27 April 2018
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Abstract
In this study, one-dimensional porous silicon nanowire (1D–PSiNW) arrays were fabricated by one-step metal-assisted chemical etching (MACE) to etch phosphorus-doped silicon wafers. The as-prepared mesoporous 1D–PSiNW arrays here had especially high specific surface areas of 323.47 m2·g−1 and were applied
[...] Read more.
In this study, one-dimensional porous silicon nanowire (1D–PSiNW) arrays were fabricated by one-step metal-assisted chemical etching (MACE) to etch phosphorus-doped silicon wafers. The as-prepared mesoporous 1D–PSiNW arrays here had especially high specific surface areas of 323.47 m2·g−1 and were applied as anodes to achieve fast charge–discharge performance for lithium ion batteries (LIBs). The 1D–PSiNWs anodes with feature size of ~7 nm exhibited reversible specific capacity of 2061.1 mAh·g−1 after 1000 cycles at a high current density of 1.5 A·g−1. Moreover, under the ultrafast charge–discharge current rate of 16.0 A·g−1, the 1D–PSiNWs anodes still maintained 586.7 mAh·g−1 capacity even after 5000 cycles. This nanoporous 1D–PSiNW with high surface area is a potential anode candidate for the ultrafast charge–discharge in LIBs with high specific capacity and superior cycling performance. Full article
(This article belongs to the Special Issue Nanomaterials and Nanofabrication for Electrochemical Energy Storage)
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Open AccessArticle Solution-Plasma-Mediated Synthesis of Si Nanoparticles for Anode Material of Lithium-Ion Batteries
Nanomaterials 2018, 8(5), 286; https://doi.org/10.3390/nano8050286
Received: 8 April 2018 / Revised: 24 April 2018 / Accepted: 25 April 2018 / Published: 27 April 2018
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Abstract
Silicon anodes have attracted considerable attention for their use in lithium-ion batteries because of their extremely high theoretical capacity; however, they are prone to extensive volume expansion during lithiation, which causes disintegration and poor cycling stability. In this article, we use two approaches
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Silicon anodes have attracted considerable attention for their use in lithium-ion batteries because of their extremely high theoretical capacity; however, they are prone to extensive volume expansion during lithiation, which causes disintegration and poor cycling stability. In this article, we use two approaches to address this issue, by reducing the size of the Si particles to nanoscale and incorporating them into a carbon composite to help modulate the volume expansion problems. We improve our previous work on the solution-plasma-mediated synthesis of Si nanoparticles (NPs) by adjusting the electrolyte medium to mild buffer solutions rather than strong acids, successfully generating Si-NPs with <10 nm diameters. We then combined these Si-NPs with carbon using MgO-template-assisted sol-gel combustion synthesis, which afforded porous carbon composite materials. Among the preparations, the composite material obtained from the LiCl 0.2 M + H3BO3 0.15 M solution-based Si-NPs exhibited a high reversible capacity of 537 mAh/g after 30 discharge/charge cycles at a current rate of 0.5 A/g. We attribute this increased reversible capacity to the decreased particle size of the Si-NPs. These results clearly show the applicability of this facile and environmentally friendly solution-plasma technique for producing Si-NPs as an anode material for lithium-ion batteries. Full article
(This article belongs to the Special Issue Plasma based Synthesis and Modification of Nanomaterials)
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Open AccessArticle Liquid-Assisted Femtosecond Laser Precision-Machining of Silica
Nanomaterials 2018, 8(5), 287; https://doi.org/10.3390/nano8050287
Received: 12 April 2018 / Revised: 21 April 2018 / Accepted: 23 April 2018 / Published: 28 April 2018
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Abstract
We report a systematical study on the liquid assisted femtosecond laser machining of quartz plate in water and under different etching solutions. The ablation features in liquid showed a better structuring quality and improved resolution with 1/3~1/2 smaller features as compared with those
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We report a systematical study on the liquid assisted femtosecond laser machining of quartz plate in water and under different etching solutions. The ablation features in liquid showed a better structuring quality and improved resolution with 1/3~1/2 smaller features as compared with those made in air. It has been demonstrated that laser induced periodic structures are present to a lesser extent when laser processed in water solutions. The redistribution of oxygen revealed a strong surface modification, which is related to the etching selectivity of laser irradiated regions. Laser ablation in KOH and HF solution showed very different morphology, which relates to the evolution of laser induced plasma on the formation of micro/nano-features in liquid. This work extends laser precision fabrication of hard materials. The mechanism of strong absorption in the regions with permittivity (epsilon) near zero is discussed. Full article
(This article belongs to the Special Issue Laser-Based Nano Fabrication and Nano Lithography)
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Open AccessArticle High-Efficiency, Near-Diffraction Limited, Dielectric Metasurface Lenses Based on Crystalline Titanium Dioxide at Visible Wavelengths
Nanomaterials 2018, 8(5), 288; https://doi.org/10.3390/nano8050288
Received: 28 March 2018 / Revised: 23 April 2018 / Accepted: 25 April 2018 / Published: 28 April 2018
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Abstract
Metasurfaces are planar optical elements that hold promise for overcoming the limitations of refractive and conventional diffractive optics. Previous metasurfaces have been limited to transparency windows at infrared wavelengths because of significant optical absorption and loss at visible wavelengths. Here we report a
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Metasurfaces are planar optical elements that hold promise for overcoming the limitations of refractive and conventional diffractive optics. Previous metasurfaces have been limited to transparency windows at infrared wavelengths because of significant optical absorption and loss at visible wavelengths. Here we report a polarization-insensitive, high-contrast transmissive metasurface composed of crystalline titanium dioxide pillars in the form of metalens at the wavelength of 633 nm. The focal spots are as small as 0.54 λ d , which is very close to the optical diffraction limit of 0.5 λ d . The simulation focusing efficiency is up to 88.5%. A rigorous method for metalens design, the phase realization mechanism and the trade-off between high efficiency and small spot size (or large numerical aperture) are discussed. Besides, the metalenses can work well with an imaging point source up to ±15° off axis. The proposed design is relatively systematic and can be applied to various applications such as visible imaging, ranging and sensing systems. Full article
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Open AccessArticle Au-Decorated Dragonfly Wing Bioscaffold Arrays as Flexible Surface-Enhanced Raman Scattering (SERS) Substrate for Simultaneous Determination of Pesticide Residues
Nanomaterials 2018, 8(5), 289; https://doi.org/10.3390/nano8050289
Received: 1 April 2018 / Revised: 18 April 2018 / Accepted: 26 April 2018 / Published: 28 April 2018
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Abstract
Rapid sampling and multicomponent analysis are vital in pesticide residue detection. In this work, we proposed a SERS platform to detect three kinds of pesticides on apple peels simultaneously by a straightforward “press and peel off” method. The flexible Au/dragonfly wing (Au/DW) substrate
[...] Read more.
Rapid sampling and multicomponent analysis are vital in pesticide residue detection. In this work, we proposed a SERS platform to detect three kinds of pesticides on apple peels simultaneously by a straightforward “press and peel off” method. The flexible Au/dragonfly wing (Au/DW) substrate was obtained from sputtering Au nanoislands on DW bioscaffold arrays by a simple direct current (DC) magnetron sputtering system. The high-performance substrate exhibited a low limit of detection (LOD) to 4-aminothiophenol (4-ATP) (10−9 M), outstanding reproducibility (less than 12.15%), good stability and suitability in multifold pesticide residues detection. Considering its excellent sample collection efficiency, the Au/DW substrate was employed to solve critical pesticide residue problems for detection of acephate (APT), cypermethrin (CPT), tsumacide (MTMC) and their multiple components on apple peels. The results show that the LOD was 10−3 ng/cm2 for APT obtained on the apple surface with a calculation equation of y = 0.26x + 6.68 and a determination coefficient (R2) of 0.970. Additionally, the LOD values for CPT and MTMC were 10−3 ng/cm2 and 10−4 ng/cm2, respectively. The finding in this work may provide a promising biomimetic SERS platform for on-spot detection of other organic pollutants in the food industry and inenvironmental protection. Full article
(This article belongs to the Special Issue Raman Imaging Methods for Nanomaterials and Bioapplications)
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Open AccessArticle Biofunctionalized Lysophosphatidic Acid/Silk Fibroin Film for Cornea Endothelial Cell Regeneration
Nanomaterials 2018, 8(5), 290; https://doi.org/10.3390/nano8050290
Received: 28 March 2018 / Revised: 25 April 2018 / Accepted: 25 April 2018 / Published: 30 April 2018
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Abstract
Cornea endothelial cells (CEnCs) tissue engineering is a great challenge to repair diseased or damaged CEnCs and require an appropriate biomaterial to support cell proliferation and differentiation. Biomaterials for CEnCs tissue engineering require biocompatibility, tunable biodegradability, transparency, and suitable mechanical properties. Silk fibroin-based
[...] Read more.
Cornea endothelial cells (CEnCs) tissue engineering is a great challenge to repair diseased or damaged CEnCs and require an appropriate biomaterial to support cell proliferation and differentiation. Biomaterials for CEnCs tissue engineering require biocompatibility, tunable biodegradability, transparency, and suitable mechanical properties. Silk fibroin-based film (SF) is known to meet these factors, but construction of functionalized graft for bioengineering of cornea is still a challenge. Herein, lysophosphatidic acid (LPA) is used to maintain and increase the specific function of CEnCs. The LPA and SF composite film (LPA/SF) was fabricated in this study. Mechanical properties and in vitro studies were performed using a rabbit model to demonstrate the characters of LPA/SF. ATR-FTIR was characterized to identify chemical composition of the films. The morphological and physical properties were performed by SEM, AFM, transparency, and contact angle. Initial cell density and MTT were performed for adhesion and cell viability in the SF and LPA/SF film. Reverse transcription polymerase chain reactions (RT-PCR) and immunofluorescence were performed to examine gene and protein expression. The results showed that films were designed appropriately for CEnCs delivery. Compared to pristine SF, LPA/SF showed higher biocompatibility, cell viability, and expression of CEnCs specific genes and proteins. These indicate that LPA/SF, a new biomaterial, offers potential benefits for CEnCs tissue engineering for regeneration. Full article
(This article belongs to the Special Issue Tissue Engineering and Regenerative Nanomedicine)
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Open AccessArticle Antimicrobial Activity of New Materials Based on Lavender and Basil Essential Oils and Hydroxyapatite
Nanomaterials 2018, 8(5), 291; https://doi.org/10.3390/nano8050291
Received: 28 March 2018 / Revised: 25 April 2018 / Accepted: 26 April 2018 / Published: 30 April 2018
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Abstract
This study presents, for the first-time, the results of a study on the hydrodynamic diameter of essential oils (EOs) of basil and lavender in water, and solutions of EOs of basil (B) and lavender (L) and hydroxyapatite (HAp). The possible influence of basil
[...] Read more.
This study presents, for the first-time, the results of a study on the hydrodynamic diameter of essential oils (EOs) of basil and lavender in water, and solutions of EOs of basil (B) and lavender (L) and hydroxyapatite (HAp). The possible influence of basil and lavender EOs on the size of hydroxyapatite nanoparticles was analyzed by Scanning Electron Microscopy (SEM). We also investigated the in vitro antimicrobial activity of plant EOs and plant EOs hydroxyapatite respectively, against Gram-positive bacteria (methicillin-resistant Staphylococcus aureus1144 (MRSA 1144) and S. aureus 1426) and Gram-negative bacteria (Escherichia coli ATCC 25922 and Escherichia coli ESBL 4493). From the autocorrelation function, obtained by Dynamic Light Scattering (DLS) measurements it was observed that basil yielded one peak at an average hydrodynamic diameter of 354.16 nm, while lavender yielded one peak at an average hydrodynamic diameter of 259.76 nm. In the case of HAp nanoparticles coated with basil (HApB) and lavender (HApL) essential oil, the aggregation was minimal. We found that the lavender EO exhibited a very good inhibitory growth activity (MIC values ranging from <0.1% for E. coli reference strain to 0.78% for S. aureus strains). The biological studies indicated that HapL material displayed an enhanced antimicrobial activity, indicating the potential use of HAp as vehicle for low concentrations of lavender EO with antibacterial properties. Flow cytometry analysis (FCM) allowed us to determine some of the potential mechanisms of the antimicrobial activities of EOs, suggesting that lavender EO was active against E. coli by interfering with membrane potential, the membrane depolarization effect being increased by incorporation of the EOs into the microporous structure of HAp. These findings could contribute to the development of new antimicrobial agents that are urgently needed for combating the antibiotic resistance phenomena. Full article
(This article belongs to the Special Issue Preparation and Application of Hybrid Nanomaterials)
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Open AccessArticle Bare Iron Oxide Nanoparticles for Magnetic Harvesting of Microalgae: From Interaction Behavior to Process Realization
Nanomaterials 2018, 8(5), 292; https://doi.org/10.3390/nano8050292
Received: 5 March 2018 / Revised: 18 April 2018 / Accepted: 27 April 2018 / Published: 1 May 2018
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Abstract
Microalgae continue to gain in importance as a bioresource, while their harvesting remains a major challenge at the moment. This study presents findings on microalgae separation using low-cost, easy-to-process bare iron oxide nanoparticles with the additional contribution of the upscaling demonstration of this
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Microalgae continue to gain in importance as a bioresource, while their harvesting remains a major challenge at the moment. This study presents findings on microalgae separation using low-cost, easy-to-process bare iron oxide nanoparticles with the additional contribution of the upscaling demonstration of this simple, adhesion-based process. The high affinity of the cell wall for the inorganic surface enables harvesting efficiencies greater than 95% for Scenedesmus ovalternus and Chlorella vulgaris. Successful separation is possible in a broad range of environmental conditions and primarily depends on the nanoparticle-to-microalgae mass ratio, whereas the effect of pH and ionic strength are less significant when the mass ratio is chosen properly. The weakening of ionic concentration profiles at the interphase due to the successive addition of deionized water leads the microalgae to detach from the nanoparticles. The process works efficiently at the liter scale, enabling complete separation of the microalgae from their medium and the separate recovery of all materials (algae, salts, and nanoparticles). The current lack of profitable harvesting processes for microalgae demands innovative approaches to encourage further development. This application of magnetic nanoparticles is an example of the prospects that nanobiotechnology offers for biomass exploitation. Full article
(This article belongs to the Special Issue Magnetic Nanoparticles in Biological Applications)
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Open AccessArticle Effect of Source/Drain Electrodes on the Electrical Properties of Silicon–Tin Oxide Thin-Film Transistors
Nanomaterials 2018, 8(5), 293; https://doi.org/10.3390/nano8050293
Received: 26 March 2018 / Revised: 25 April 2018 / Accepted: 26 April 2018 / Published: 2 May 2018
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Abstract
Ultra-high definition displays have become a trend for the current flat plane displays. In this study, the contact properties of amorphous silicon–tin oxide thin-film transistors (a-STO TFTs) employed with source/drain (S/D) electrodes were analyzed. Ohmic contact with a good device performance was achieved
[...] Read more.
Ultra-high definition displays have become a trend for the current flat plane displays. In this study, the contact properties of amorphous silicon–tin oxide thin-film transistors (a-STO TFTs) employed with source/drain (S/D) electrodes were analyzed. Ohmic contact with a good device performance was achieved when a-STO was matched with indium-tin-oxide (ITO) or Mo electrodes. The acceptor-like densities of trap states (DOS) of a-STO TFTs were further investigated by using low-frequency capacitance–voltage (C–V) characteristics to understand the impact of the electrode on the device performance. The reason of the distinct electrical performances of the devices with ITO and Mo contacts was attributed to different DOS caused by the generation of local defect states near the electrodes, which distorted the electric field distribution and formed an electrical potential barrier hindering the flow of electrons. It is of significant importance for circuit designers to design reliable integrated circuits with SnO2-based devices applied in flat panel displays. Full article
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Open AccessArticle Synthesis of Si, N co-Doped Nano-Sized TiO2 with High Thermal Stability and Photocatalytic Activity by Mechanochemical Method
Nanomaterials 2018, 8(5), 294; https://doi.org/10.3390/nano8050294
Received: 3 April 2018 / Revised: 23 April 2018 / Accepted: 1 May 2018 / Published: 2 May 2018
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Abstract
Τhe photocatalytic activity in the range of visible light wavelengths and the thermal stability of the structure were significantly enhanced in Si, N co-doped nano-sized TiO2, and synthesized through high-energy mechanical milling of TiO2 and SiO2 powders, which was
[...] Read more.
Τhe photocatalytic activity in the range of visible light wavelengths and the thermal stability of the structure were significantly enhanced in Si, N co-doped nano-sized TiO2, and synthesized through high-energy mechanical milling of TiO2 and SiO2 powders, which was followed by calcination at 600 °C in an ammonia atmosphere. High-energy mechanical milling had a pronounced effect on the mixing and the reaction between the starting powders and greatly favored the transformation of the resultant powder mixture into an amorphous phase that contained a large number of evenly-dispersed nanocrystalline TiO2 particles as anatase seeds. The experimental results suggest that the elements were homogeneously dispersed at an atomic level in this amorphous phase. After calcination, most of the amorphous phase was crystallized, which resulted in a unique nano-sized crystalline-core/disordered-shell morphology. This novel experimental process is simple, template-free, and provides features of high reproducibility in large-scale industrial production. Full article
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Open AccessArticle Engineering a 3D-Bioprinted Model of Human Heart Valve Disease Using Nanoindentation-Based Biomechanics
Nanomaterials 2018, 8(5), 296; https://doi.org/10.3390/nano8050296
Received: 2 April 2018 / Revised: 18 April 2018 / Accepted: 24 April 2018 / Published: 3 May 2018
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Abstract
In calcific aortic valve disease (CAVD), microcalcifications originating from nanoscale calcifying vesicles disrupt the aortic valve (AV) leaflets, which consist of three (biomechanically) distinct layers: the fibrosa, spongiosa, and ventricularis. CAVD has no pharmacotherapy and lacks in vitro models as a result of
[...] Read more.
In calcific aortic valve disease (CAVD), microcalcifications originating from nanoscale calcifying vesicles disrupt the aortic valve (AV) leaflets, which consist of three (biomechanically) distinct layers: the fibrosa, spongiosa, and ventricularis. CAVD has no pharmacotherapy and lacks in vitro models as a result of complex valvular biomechanical features surrounding resident mechanosensitive valvular interstitial cells (VICs). We measured layer-specific mechanical properties of the human AV and engineered a three-dimensional (3D)-bioprinted CAVD model that recapitulates leaflet layer biomechanics for the first time. Human AV leaflet layers were separated by microdissection, and nanoindentation determined layer-specific Young’s moduli. Methacrylated gelatin (GelMA)/methacrylated hyaluronic acid (HAMA) hydrogels were tuned to duplicate layer-specific mechanical characteristics, followed by 3D-printing with encapsulated human VICs. Hydrogels were exposed to osteogenic media (OM) to induce microcalcification, and VIC pathogenesis was assessed by near infrared or immunofluorescence microscopy. Median Young’s moduli of the AV layers were 37.1, 15.4, and 26.9 kPa (fibrosa/spongiosa/ventricularis, respectively). The fibrosa and spongiosa Young’s moduli matched the 3D 5% GelMa/1% HAMA UV-crosslinked hydrogels. OM stimulation of VIC-laden bioprinted hydrogels induced microcalcification without apoptosis. We report the first layer-specific measurements of human AV moduli and a novel 3D-bioprinted CAVD model that potentiates microcalcification by mimicking the native AV mechanical environment. This work sheds light on valvular mechanobiology and could facilitate high-throughput drug-screening in CAVD. Full article
(This article belongs to the Special Issue Nano-scale Mechanics of Biological Materials)
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Open AccessArticle Non-Aqueous Sol-Gel Synthesis of FePt Nanoparticles in the Absence of In Situ Stabilizers
Nanomaterials 2018, 8(5), 297; https://doi.org/10.3390/nano8050297
Received: 31 March 2018 / Revised: 24 April 2018 / Accepted: 30 April 2018 / Published: 3 May 2018
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Abstract
The synthesis of FePt nanocrystals is typically performed in an organic solvent at rather high temperatures, demanding the addition of the in situ stabilizers oleic acid and oleylamine to produce monomodal particles with well-defined morphologies. Replacing frequently-used solvents with organic media bearing functional
[...] Read more.
The synthesis of FePt nanocrystals is typically performed in an organic solvent at rather high temperatures, demanding the addition of the in situ stabilizers oleic acid and oleylamine to produce monomodal particles with well-defined morphologies. Replacing frequently-used solvents with organic media bearing functional moieties, the use of the stabilizers can be completely circumvented. In addition, various morphologies and sizes of the nanocrystals can be achieved by the choice of organic solvent. The kinetics of particle growth and the change in the magnetic behavior of the superparamagnetic FePt nanocrystals during the synthesis with a set of different solvents, as well as the resulting morphologies and stoichiometries of the nanoparticles were determined by powder X-ray diffraction (PXRD), small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), inductively coupled plasma optical emission spectroscopy (ICP-OES)/mass spectrometry (ICP-MS), and superconducting quantum interference device (SQUID) measurements. Furthermore, annealing of the as-prepared FePt nanoparticles led to the ordered L10 phase and, thus, to hard magnetic materials with varying saturation magnetizations and magnetic coercivities. Full article
(This article belongs to the Special Issue Sol-Gel Preparation of Nanomaterials)
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Open AccessArticle Stochastic Resonance and Safe Basin of Single-Walled Carbon Nanotubes with Strongly Nonlinear Stiffness under Random Magnetic Field
Nanomaterials 2018, 8(5), 298; https://doi.org/10.3390/nano8050298
Received: 19 March 2018 / Revised: 24 April 2018 / Accepted: 25 April 2018 / Published: 4 May 2018
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Abstract
In this paper, a kind of single-walled carbon nanotube nonlinear model is developed and the strongly nonlinear dynamic characteristics of such carbon nanotubes subjected to random magnetic field are studied. The nonlocal effect of the microstructure is considered based on Eringen’s differential constitutive
[...] Read more.
In this paper, a kind of single-walled carbon nanotube nonlinear model is developed and the strongly nonlinear dynamic characteristics of such carbon nanotubes subjected to random magnetic field are studied. The nonlocal effect of the microstructure is considered based on Eringen’s differential constitutive model. The natural frequency of the strongly nonlinear dynamic system is obtained by the energy function method, the drift coefficient and the diffusion coefficient are verified. The stationary probability density function of the system dynamic response is given and the fractal boundary of the safe basin is provided. Theoretical analysis and numerical simulation show that stochastic resonance occurs when varying the random magnetic field intensity. The boundary of safe basin has fractal characteristics and the area of safe basin decreases when the intensity of the magnetic field permeability increases. Full article
(This article belongs to the Special Issue Applications of Carbon Nanotubes)
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Open AccessArticle Comparative Study of the ORR Activity and Stability of Pt and PtM (M = Ni, Co, Cr, Pd) Supported on Polyaniline/Carbon Nanotubes in a PEM Fuel Cell
Nanomaterials 2018, 8(5), 299; https://doi.org/10.3390/nano8050299
Received: 19 April 2018 / Revised: 28 April 2018 / Accepted: 2 May 2018 / Published: 4 May 2018
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Abstract
The oxygen reduction reaction (ORR) activity and stability of platinum (Pt) and PtM (M = Ni, Co, Cr, Pd) supported on polyaniline/carbon nanotube (PtM/PANI-CNT) were explored and compared with the commercial Pt/C catalyst (ETEK). The Pt/PANI-CNT catalyst exhibited higher ORR activity and stability
[...] Read more.
The oxygen reduction reaction (ORR) activity and stability of platinum (Pt) and PtM (M = Ni, Co, Cr, Pd) supported on polyaniline/carbon nanotube (PtM/PANI-CNT) were explored and compared with the commercial Pt/C catalyst (ETEK). The Pt/PANI-CNT catalyst exhibited higher ORR activity and stability than the commercial Pt/C catalyst even though it had larger crystallite/particle sizes, lower catalyst dispersion and lower electrochemical surface area (ESA), probably because of its high electrical conductivity. The addition of second metal (M) enhanced the ORR activity and stability of the Pt/PANI-CNT catalyst, because the added M induced the formation of a PtM alloy and shifted the d-band center to downfield, leading to a weak chemical interaction between oxygenated species and the catalyst surface and, therefore, affected positively the catalytic activity. Among all the tested M, the addition of Cr was optimal. Although it improved the ORR activity of the Pt/PANI-CNT catalyst slightly less than that of Pd (around 4.98%) in low temperature (60 °C)/pressure (1 atm abs), it reduced the ESA loss by around 14.8% after 1000 cycles of repetitive cyclic voltammetry (CV). In addition, it is cheaper than Pd metal. Thus, Cr was recommended as the second metal to alloy with Pt on the PANI-CNT support. Full article
(This article belongs to the Special Issue Nanomaterials in Environmental Friendly Fuel Cell)
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Open AccessArticle Synthesis of Iron Oxide/Gold Composite Nanoparticles Using Polyethyleneimine as a Polymeric Active Stabilizer for Development of a Dual Imaging Probe
Nanomaterials 2018, 8(5), 300; https://doi.org/10.3390/nano8050300
Received: 5 April 2018 / Revised: 27 April 2018 / Accepted: 3 May 2018 / Published: 5 May 2018
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Abstract
The combination of magnetic and plasmonic properties using iron oxide/gold nanocomposite particles is crucial for the development of multimodal molecular imaging probes. In this study, iron oxide/gold composite nanoparticles (NanoIOGs) were synthesized via the on-site reduction of an Au precursor salt by polyethyleneimine
[...] Read more.
The combination of magnetic and plasmonic properties using iron oxide/gold nanocomposite particles is crucial for the development of multimodal molecular imaging probes. In this study, iron oxide/gold composite nanoparticles (NanoIOGs) were synthesized via the on-site reduction of an Au precursor salt by polyethyleneimine (PEI) molecules attached to iron oxide nanoparticles (IONPs), and they were employed in magnetic resonance and dark-field microscope imaging. PEI is considered as a polymeric active stabilizer (PAS), acting as a reducing agent for the synthesis of Au and a dispersant for nanoparticles. When the IONPs prepared at the PEI concentration of 0.02 wt. % were used for the NanoIOG synthesis, Au nanoseeds were formed around the IONPs. The alloy clusters of IONPs/Au crystals were produced with further reduction depending on PEI concentration. The NanoIOGs exhibited superparamagnetism in a magnetic field and plasmonic response in a dark-field (DF) microscope. The sizes, morphologies, magnetizations, and r2 relaxivities of NanoIOGs were affected significantly by the amount of PEI added during the NanoIOG synthesis. It is suggested that the PAS-mediated synthesis is simple and effective, and can be applied to various nanostructured Au-metal alloys. Full article
(This article belongs to the Special Issue Organic-Inorganic Hybrid Nanomaterials)
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Open AccessArticle A Hollow-Structured Manganese Oxide Cathode for Stable Zn-MnO2 Batteries
Nanomaterials 2018, 8(5), 301; https://doi.org/10.3390/nano8050301
Received: 3 April 2018 / Revised: 26 April 2018 / Accepted: 27 April 2018 / Published: 5 May 2018
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Abstract
Aqueous rechargeable zinc-manganese dioxide (Zn-MnO2) batteries are considered as one of the most promising energy storage devices for large scale-energy storage systems due to their low cost, high safety, and environmental friendliness. However, only a few cathode materials have been demonstrated
[...] Read more.
Aqueous rechargeable zinc-manganese dioxide (Zn-MnO2) batteries are considered as one of the most promising energy storage devices for large scale-energy storage systems due to their low cost, high safety, and environmental friendliness. However, only a few cathode materials have been demonstrated to achieve stable cycling for aqueous rechargeable Zn-MnO2 batteries. Here, we report a new material consisting of hollow MnO2 nanospheres, which can be used for aqueous Zn-MnO2 batteries. The hollow MnO2 nanospheres can achieve high specific capacity up to ~405 mAh g−1 at 0.5 C. More importantly, the hollow structure of birnessite-type MnO2 enables long-term cycling stability for the aqueous Zn-MnO2 batteries. The excellent performance of the hollow MnO2 nanospheres should be due to their unique structural properties that enable the easy intercalation of zinc ions. Full article
(This article belongs to the Special Issue Nanomaterials and Nanofabrication for Electrochemical Energy Storage)
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Open AccessArticle Carbon-Based Fe3O4 Nanocomposites Derived from Waste Pomelo Peels for Magnetic Solid-Phase Extraction of 11 Triazole Fungicides in Fruit Samples
Nanomaterials 2018, 8(5), 302; https://doi.org/10.3390/nano8050302
Received: 29 March 2018 / Revised: 26 April 2018 / Accepted: 1 May 2018 / Published: 6 May 2018
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Abstract
Carbon-based Fe3O4 nanocomposites (C/Fe3O4 NCs) were synthesized by a simple one-step hydrothermal method using waste pomelo peels as the carbon precursors. The characterization results showed that they had good structures and physicochemical properties. The prepared C/Fe3
[...] Read more.
Carbon-based Fe3O4 nanocomposites (C/Fe3O4 NCs) were synthesized by a simple one-step hydrothermal method using waste pomelo peels as the carbon precursors. The characterization results showed that they had good structures and physicochemical properties. The prepared C/Fe3O4 NCs could be applied as excellent and recyclable adsorbents for magnetic solid phase extraction (MSPE) of 11 triazole fungicides in fruit samples. In the MSPE procedure, several parameters including the amount of adsorbents, extraction time, the type and volume of desorption solvent, and desorption time were optimized in detail. Under the optimized conditions, the good linearity (R2 > 0.9916), the limits of detection (LOD), and quantification (LOQ) were obtained in the range of 1–100, 0.12–0.55, and 0.39–1.85 μg/kg for 11 pesticides, respectively. Lastly, the proposed MSPE method was successfully applied to analyze triazole fungicides in real apple, pear, orange, peach, and banana samples with recoveries in the range of 82.1% to 109.9% and relative standard deviations (RSDs) below 8.4%. Therefore, the C/Fe3O4 NCs based MSPE method has a great potential for isolating and pre-concentrating trace levels of triazole fungicides in fruits. Full article
(This article belongs to the Special Issue Preparation and Application of Hybrid Nanomaterials)
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Open AccessArticle Novel Sulfur/Ethylenediamine-Functionalized Reduced Graphene Oxide Composite as Cathode Material for High-performance Lithium-Sulfur Batteries
Nanomaterials 2018, 8(5), 303; https://doi.org/10.3390/nano8050303
Received: 31 March 2018 / Revised: 1 May 2018 / Accepted: 1 May 2018 / Published: 6 May 2018
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Abstract
Sulfur/ethylenediamine-functionalized reduced graphene oxide (S/EDA-RGO) nanocomposites were synthesized using a simple process. Ethylenediamine (EDA) was employed as both the reducing agent and the modification component. The morphologies, microstructures, and compositions of S/EDA-RGO composites were characterized by various detection techniques. The data indicated that
[...] Read more.
Sulfur/ethylenediamine-functionalized reduced graphene oxide (S/EDA-RGO) nanocomposites were synthesized using a simple process. Ethylenediamine (EDA) was employed as both the reducing agent and the modification component. The morphologies, microstructures, and compositions of S/EDA-RGO composites were characterized by various detection techniques. The data indicated that EDA-RGO used as scaffolds for sulfur cathodes could enhance the electronic conductivity of the composites and strengthen the adsorbability of polysulfides. Meanwhile, the electrochemical properties of both S/EDA-RGO and S/RGO composites that were used as cathodes for lithium-sulfur (Li-S) batteries were investigated. The initial discharge capacity of S/EDA-RGO composites reached 1240 mAh g−1, with reversible capacity being maintained at 714 mAh g−1 after 100 cycles. The improvement in cycling stability of S/EDA-RGO composites was further verified at different current rates. These findings demonstrated that proper surface modification of RGO by EDA reducing agent might improve the electrochemical performances of Li–S batteries. Full article
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Open AccessArticle A Method for Efficient Loading of Ciprofloxacin Hydrochloride in Cationic Solid Lipid Nanoparticles: Formulation and Microbiological Evaluation
Nanomaterials 2018, 8(5), 304; https://doi.org/10.3390/nano8050304
Received: 27 February 2018 / Revised: 9 April 2018 / Accepted: 2 May 2018 / Published: 6 May 2018
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Abstract
The aim of the study was the production of solid lipid nanoparticles (SLN) loaded with ciprofloxacin (CIP) through two different production techniques, quasi-emulsion solvent diffusion (QESD) and solvent injection (SI). In order to efficaciously entrap the commercial salt form (hydrochloride) of the antibiotic
[...] Read more.
The aim of the study was the production of solid lipid nanoparticles (SLN) loaded with ciprofloxacin (CIP) through two different production techniques, quasi-emulsion solvent diffusion (QESD) and solvent injection (SI). In order to efficaciously entrap the commercial salt form (hydrochloride) of the antibiotic in these lipid systems, a conversion of CIP hydrochloride to the free base was realized in situ, through the addition of triethylamine. To ensure physical stability to the carriers over time and ameliorate the interaction with bacterial cell membranes, positively charged SLN were produced by addition of the cationic lipid didecyldimethylammonium bromide (DDAB). Homogeneous SLN populations with a mean particle sizes of 250–350 nm were produced by both methods; drug encapsulation was over 85% for most samples. The SLN were physically stable for up to nine months both at 4 °C and 25 °C, although the former condition appears more suitable to guarantee the maintenance of the initial particle size distribution. As expected, CIP encapsulation efficiency underwent a slight reduction after nine months of storage, although the initial high drug content values would ensure a residual concentration of the antibiotic in the SLN still appropriate to exert an acceptable antibacterial activity. Selected SLN formulations were subjected to an in vitro microbiological assay against different bacterial strains, to verify the effect of nanoencapsulation on the cell growth inhibitory activity of CIP. In general, CIP-SLN produced without DDAB showed MIC values for CIP comparable to those of the free drug. Conversely, addition of increasing percentages of the cationic lipid, reflected by a progressive increase of the positive value of the Zeta potential, showed a variety of MIC values against the various bacterial strains, but with values 2–4 order of dilution lower than free CIP. An hypothesis of the effect of the cationic lipid upon the increased antibacterial activity of CIP in the nanocarriers is also formulated. Full article
(This article belongs to the Special Issue Antibacterial Activity of Nanomaterials)
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Open AccessArticle Mechanical and Physicochemical Properties of Newly Formed ZnO-PMMA Nanocomposites for Denture Bases
Nanomaterials 2018, 8(5), 305; https://doi.org/10.3390/nano8050305
Received: 21 March 2018 / Revised: 25 April 2018 / Accepted: 30 April 2018 / Published: 6 May 2018
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Abstract
Aim: The aim of this study was to investigate the selected properties of zinc oxide- polymethyl methacrylate (ZnO-PMMA) nanocomposites that can influence the microorganism deposition on their surface. Materials and Methods: Non-commercial ZnO-NPs were prepared, characterized and used for the preparation of PMMA
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Aim: The aim of this study was to investigate the selected properties of zinc oxide- polymethyl methacrylate (ZnO-PMMA) nanocomposites that can influence the microorganism deposition on their surface. Materials and Methods: Non-commercial ZnO-NPs were prepared, characterized and used for the preparation of PMMA nanocomposite. Roughness, absorbability, contact angle and hardness of this new nanomaterial were evaluated. PMMA without ZnO-NPs served as control. Outcomes: Compared to unenriched PMMA, incorporation of ZnO-NPs to 7.5% for PMMA nanocomposite increases the hardness (by 5.92%) and the hydrophilicity. After modification of the material with zinc oxide nanoparticles the roughness parameter did not change. All tested materials showed absorption within the range of 1.82 to 2.03%, which meets the requirements of International Organization for Standardization (ISO) standards for denture base polymers. Conclusions: The results showed no significant deterioration in the properties of acrylic resin that could disqualify the nanocomposite for clinical use. Increased hydrophilicity and hardness with absorbability within the normal range can explain the reduced microorganism growth on the denture base, as has been proven in a previous study. Full article
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Open AccessArticle Soy Protein Isolate-Phosphatidylcholine Nanoemulsions Prepared Using High-Pressure Homogenization
Nanomaterials 2018, 8(5), 307; https://doi.org/10.3390/nano8050307
Received: 12 April 2018 / Revised: 29 April 2018 / Accepted: 4 May 2018 / Published: 7 May 2018
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Abstract
The nanoemulsions of soy protein isolate-phosphatidylcholine (SPI-PC) with different emulsion conditions were studied. Homogenization pressure and homogenization cycle times were varied, along with SPI and PC concentration. Evaluations included turbidity, particle size, ζ-potential, particle distribution index, and turbiscan stability index (TSI). The nanoemulsions
[...] Read more.
The nanoemulsions of soy protein isolate-phosphatidylcholine (SPI-PC) with different emulsion conditions were studied. Homogenization pressure and homogenization cycle times were varied, along with SPI and PC concentration. Evaluations included turbidity, particle size, ζ-potential, particle distribution index, and turbiscan stability index (TSI). The nanoemulsions had the best stability when SPI was at 1.5%, PC was at 0.22%, the homogenization pressure was 100 MPa and homogenization was performed 4 times. The average particle size of the SPI-PC nanoemulsions was 217 nm, the TSI was 3.02 and the emulsification yield was 93.4% of nanoemulsions. Full article
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Open AccessArticle Transition Metal Hollow Nanocages as Promising Cathodes for the Long-Term Cyclability of Li–O2 Batteries
Nanomaterials 2018, 8(5), 308; https://doi.org/10.3390/nano8050308
Received: 19 March 2018 / Revised: 27 April 2018 / Accepted: 2 May 2018 / Published: 7 May 2018
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Abstract
As a step towards efficient and cost-effective electrocatalytic cathodes for Li–O2 batteries, highly porous hausmannite-type Mn3O4 hollow nanocages (MOHNs) of a large diameter of ~250 nm and a high surface area of 90.65 m2·g−1 were synthesized
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As a step towards efficient and cost-effective electrocatalytic cathodes for Li–O2 batteries, highly porous hausmannite-type Mn3O4 hollow nanocages (MOHNs) of a large diameter of ~250 nm and a high surface area of 90.65 m2·g−1 were synthesized and their physicochemical and electrochemical properties were studied in addition to their formation mechanism. A facile approach using carbon spheres as the template and MnCl2 as the precursor was adopted to suit the purpose. The MOHNs/Ketjenblack cathode-based Li–O2 battery demonstrated an improved cyclability of 50 discharge–charge cycles at a specific current of 400 mA·g−1 and a specific capacity of 600 mAh·g−1. In contrast, the Ketjenblack cathode-based one can sustain only 15 cycles under the same electrolytic system comprised of 1 M LiTFSI/TEGDME. It is surmised that the unique hollow nanocage morphology of MOHNs is responsible for the high electrochemical performance. The hollow nanocages were a result of the aggregation of crystalline nanoparticles of 25–35 nm size, and the mesoscopic pores between the nanoparticles gave rise to a loosely mesoporous structure for accommodating the volume change in the MOHNs/Ketjenblack cathode during electrocatalytic reactions. The improved cyclic stability is mainly due to the faster mass transport of the O2 through the mesoscopic pores. This work is comparable to the state-of-the-art experimentations on cathodes for Li–O2 batteries that focus on the use of non-precious transition materials. Full article
(This article belongs to the Special Issue Nanomaterials for Renewable and Sustainable Energy)
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Open AccessArticle In-Situ Preparation of Aramid-Multiwalled CNT Nano-Composites: Morphology, Thermal Mechanical and Electric Properties
Nanomaterials 2018, 8(5), 309; https://doi.org/10.3390/nano8050309
Received: 1 April 2018 / Revised: 30 April 2018 / Accepted: 1 May 2018 / Published: 7 May 2018
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Abstract
In this work in-situ polymerization technique has been used to chemically link the functionalized multiwalled carbon nanotubes (CNTs) with aramid matrix chains. Phenylene diamine monomers were reacted in the first stage with the carboxylic acid functionalized CNTs and then amidized in-situ using terephthaloyl
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In this work in-situ polymerization technique has been used to chemically link the functionalized multiwalled carbon nanotubes (CNTs) with aramid matrix chains. Phenylene diamine monomers were reacted in the first stage with the carboxylic acid functionalized CNTs and then amidized in-situ using terephthaloyl chloride generating chemically bonded CNTs with the matrix. Various proportions of the CNTs were used to prepare the hybrid materials. The functionalization procedure was studied by Fourier transform infrared (FTIR) spectroscopy and composite morphology investigated by scanning electron microscopy (SEM). Thermal mechanical properties of these hybrids, together with those where pristine CNTs with similar loadings were used, are compared using tensile and dynamic mechanical analysis (DMA). The tensile strength and temperature involving α-relaxations on CNT loading increased with CNT loading in both systems, but much higher values, i.e., 267 MPa and 353 °C, respectively, were obtained in the chemically bonded system, which are related to the nature of the interface developed as observed in SE micrographs. The water absorption capacity of the films was significantly reduced from 6.2 to 1.45% in the presence pristine CNTs. The inclusion of pristine CNTs increased the electric conductivity of the aramid films with a minimum threshold value at the loading of 3.5 wt % of CNTs. Such mechanically strong and thermally stable aramid and easily processable composites can be suitable for various applications including high performance films, electromagnetic shielding and radar absorption. Full article
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Open AccessArticle Characterization of Nanoparticle Batch-To-Batch Variability
Nanomaterials 2018, 8(5), 311; https://doi.org/10.3390/nano8050311
Received: 20 March 2018 / Revised: 20 April 2018 / Accepted: 4 May 2018 / Published: 8 May 2018
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Abstract
A central challenge for the safe design of nanomaterials (NMs) is the inherent variability of NM properties, both as produced and as they interact with and evolve in, their surroundings. This has led to uncertainty in the literature regarding whether the biological and
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A central challenge for the safe design of nanomaterials (NMs) is the inherent variability of NM properties, both as produced and as they interact with and evolve in, their surroundings. This has led to uncertainty in the literature regarding whether the biological and toxicological effects reported for NMs are related to specific NM properties themselves, or rather to the presence of impurities or physical effects such as agglomeration of particles. Thus, there is a strong need for systematic evaluation of the synthesis and processing parameters that lead to potential variability of different NM batches and the reproducible production of commonly utilized NMs. The work described here represents over three years of effort across 14 European laboratories to assess the reproducibility of nanoparticle properties produced by the same and modified synthesis routes for four of the OECD priority NMs (silica dioxide, zinc oxide, cerium dioxide and titanium dioxide) as well as amine-modified polystyrene NMs, which are frequently employed as positive controls for nanotoxicity studies. For 46 different batches of the selected NMs, all physicochemical descriptors as prioritized by the OECD have been fully characterized. The study represents the most complete assessment of NMs batch-to-batch variability performed to date and provides numerous important insights into the potential sources of variability of NMs and how these might be reduced. Full article
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Open AccessArticle Short-Range Correlated Magnetic Core-Shell CrO2/Cr2O3 Nanorods: Experimental Observations and Theoretical Considerations
Nanomaterials 2018, 8(5), 312; https://doi.org/10.3390/nano8050312
Received: 14 March 2018 / Revised: 1 May 2018 / Accepted: 7 May 2018 / Published: 9 May 2018
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Abstract
With the evolution of synthesis and the critical characterization of core-shell nanostructures, short-range magnetic correlation is of prime interest in employing their properties to develop novel devices and widespread applications. In this regard, a novel approach of the magnetic core-shell saturated magnetization (CSSM)
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With the evolution of synthesis and the critical characterization of core-shell nanostructures, short-range magnetic correlation is of prime interest in employing their properties to develop novel devices and widespread applications. In this regard, a novel approach of the magnetic core-shell saturated magnetization (CSSM) cylinder model solely based on the contribution of saturated magnetization in one-dimensional CrO2/Cr2O3 core-shell nanorods (NRs) has been developed and applied for the determination of core-diameter and shell-thickness. The nanosized effect leads to a short-range magnetic correlation of ferromagnetic core-CrO2 extracted from CSSM, which can be explained using finite size scaling method. The outcome of this study is important in terms of utilizing magnetic properties for the critical characterization of core-shell nanomagnetic materials. Full article
(This article belongs to the Special Issue Ferromagnetic and Magnetic Properties of Nanostructures)
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Open AccessArticle A Facile Approach for the Synthesis of Zn2SnO4/BiOBr Hybrid Nanocomposites with Improved Visible-Light Photocatalytic Performance
Nanomaterials 2018, 8(5), 313; https://doi.org/10.3390/nano8050313
Received: 25 March 2018 / Revised: 22 April 2018 / Accepted: 3 May 2018 / Published: 9 May 2018
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Abstract
In this study, a novel Zn2SnO4/BiOBr hybrid photocatalyst was prepared via a mild hydrothermal synthesis combined with a chemical deposition method. The morphological structure, chemical composition, crystal structure, and optical properties were comprehensively characterized by a series of measurement
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In this study, a novel Zn2SnO4/BiOBr hybrid photocatalyst was prepared via a mild hydrothermal synthesis combined with a chemical deposition method. The morphological structure, chemical composition, crystal structure, and optical properties were comprehensively characterized by a series of measurement techniques. Morphological observation showed that fine Zn2SnO4 nanoparticles were anchored on the nanoplate surface of a flower-like BiOBr 3D hierarchical structure. The experimental results of UV-vis diffuse reflection spectroscopy revealed that the visible-light absorptive capacity of the Zn2SnO4/BiOBr hybrid photocatalyst was promoted, as compared to that of pure Zn2SnO4. Evidenced by electro-negativity theoretical calculation, Zn2SnO4 and BiOBr possessed matched band edges for accelerating photogenerated charge separation at the interface. The Zn2SnO4/BiOBr hybrid photocatalyst exhibited enhanced photocatalytic performance in the degradation of Rhodamine B (RhB) under visible light irradiation. According to the band energy structure and the experimental results, the enhanced photocatalytic performance was ascribed to the improved visible-light absorptive capacity and the contact interface between Zn2SnO4 nanoparticles and BiOBr nanoplates, being able to favor the prompt charge migration and suppress the recombination of photogenerated carriers in the hybrid system. Full article
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Open AccessArticle Barrier Properties of Layered-Silicate Reinforced Ethylenepropylenediene Monomer/Chloroprene Rubber Nanorubbers
Nanomaterials 2018, 8(5), 314; https://doi.org/10.3390/nano8050314
Received: 10 April 2018 / Revised: 2 May 2018 / Accepted: 3 May 2018 / Published: 9 May 2018
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Abstract
The triacetin and nitroglycerin barrier properties of layered-silicate reinforced ethylenepropylenediene monomer/chloroprene rubber (EPDM/CR) nanorubbers were investigated as rocket-propellant inhibitors. EPDM/CR nanorubbers with intercalated structures were formulated and prepared by the melt-compounding method. The triacetin permeability and nitroglycerin absorption were observed to decrease with
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The triacetin and nitroglycerin barrier properties of layered-silicate reinforced ethylenepropylenediene monomer/chloroprene rubber (EPDM/CR) nanorubbers were investigated as rocket-propellant inhibitors. EPDM/CR nanorubbers with intercalated structures were formulated and prepared by the melt-compounding method. The triacetin permeability and nitroglycerin absorption were observed to decrease with increasing layered-silicate content. The layered silicates also improved the flame retardancies of the nanorubbers by forming silicate reinforced carbonaceous chars. Layered-silicate reinforced EPDM/CR nanorubbers are potentially effective rocket propellant-inhibiting materials. Full article
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Open AccessArticle Iron Oxide Colloidal Nanoclusters as Theranostic Vehicles and Their Interactions at the Cellular Level
Nanomaterials 2018, 8(5), 315; https://doi.org/10.3390/nano8050315
Received: 16 April 2018 / Revised: 4 May 2018 / Accepted: 4 May 2018 / Published: 9 May 2018
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Abstract
Advances in surfactant-assisted chemical approaches have led the way for the exploitation of nanoscale inorganic particles in medical diagnosis and treatment. In this field, magnetically-driven multimodal nanotools that perform both detection and therapy, well-designed in size, shape and composition, are highly advantageous. Such
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Advances in surfactant-assisted chemical approaches have led the way for the exploitation of nanoscale inorganic particles in medical diagnosis and treatment. In this field, magnetically-driven multimodal nanotools that perform both detection and therapy, well-designed in size, shape and composition, are highly advantageous. Such a theranostic material—which entails the controlled assembly of smaller (maghemite) nanocrystals in a secondary motif that is highly dispersible in aqueous media—is discussed here. These surface functionalized, pomegranate-like ferrimagnetic nanoclusters (40–85 nm) are made of nanocrystal subunits that show a remarkable magnetic resonance imaging contrast efficiency, which is better than that of the superparamagnetic contrast agent Endorem©. Going beyond this attribute and with their demonstrated low cytotoxicity in hand, we examine the critical interaction of such nanoprobes with cells at different physiological environments. The time-dependent in vivo scintigraphic imaging of mice experimental models, combined with a biodistribution study, revealed the accumulation of nanoclusters in the spleen and liver. Moreover, the in vitro proliferation of spleen cells and cytokine production witnessed a size-selective regulation of immune system cells, inferring that smaller clusters induce mainly inflammatory activities, while larger ones induce anti-inflammatory actions. The preliminary findings corroborate that the modular chemistry of magnetic iron oxide nanoclusters stimulates unexplored pathways that could be driven to alter their function in favor of healthcare. Full article
(This article belongs to the Special Issue Magnetic Nanoparticles in Biological Applications)
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Open AccessArticle Optimization of Synthesis Conditions of Carbon Nanotubes via Ultrasonic-Assisted Floating Catalyst Deposition Using Response Surface Methodology
Nanomaterials 2018, 8(5), 316; https://doi.org/10.3390/nano8050316
Received: 20 March 2018 / Revised: 4 May 2018 / Accepted: 7 May 2018 / Published: 9 May 2018
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Abstract
The growing use of carbon nanotubes (CNTs) in a plethora of applications has provided to us a motivation to investigate CNT synthesis by new methods. In this study, ultrasonic-assisted chemical vapor deposition (CVD) method was employed to synthesize CNTs. The difficulty of controlling
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The growing use of carbon nanotubes (CNTs) in a plethora of applications has provided to us a motivation to investigate CNT synthesis by new methods. In this study, ultrasonic-assisted chemical vapor deposition (CVD) method was employed to synthesize CNTs. The difficulty of controlling the size of clusters and achieving uniform distribution—the major problem in previous methods—was solved by using ultrasonic bath and dissolving ferrocene in xylene outside the reactor. The operating conditions were optimized using a rotatable central composite design (CCD), which helped optimize the operating conditions of the method. Response surface methodology (RSM) was used to analyze these experiments. Using statistical software was very effective, considering that it decreased the number of experiments needed to achieve the optimum conditions. Synthesis of CNTs was studied as a function of three independent parameters viz. hydrogen flow rate (120–280 cm3/min), catalyst concentration (2–6 wt %), and synthesis temperature (800–1200 °C). Optimum conditions for the synthesis of CNTs were found to be 3.78 wt %, 184 cm3/min, and 976 °C for catalyst concentration, hydrogen flow rate, and synthesis temperature, respectively. Under these conditions, Raman spectrum indicates high values of (IG/ID), which means high-quality CNTs. Full article
(This article belongs to the Special Issue Applications of Carbon Nanotubes)
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Open AccessArticle Synthesis of Nano-Zinc Oxide Loaded on Mesoporous Silica by Coordination Effect and Its Photocatalytic Degradation Property of Methyl Orange
Nanomaterials 2018, 8(5), 317; https://doi.org/10.3390/nano8050317
Received: 28 March 2018 / Revised: 6 May 2018 / Accepted: 7 May 2018 / Published: 9 May 2018
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Abstract
Salicylaldimine-modified mesoporous silica (Sal-MCM-3 and Sal-MCM-9) was prepared through a co-condensation method with different amounts of added salicylaldimine. With the coordination from the salicylaldimine, zinc ions were impregnated on Sal-MCM-3 and Sal-MCM-9. Then, Zn-Sal-MCM-3 and Zn-Sal-MCM-9 were calcined to obtain nano-zinc oxide loaded
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Salicylaldimine-modified mesoporous silica (Sal-MCM-3 and Sal-MCM-9) was prepared through a co-condensation method with different amounts of added salicylaldimine. With the coordination from the salicylaldimine, zinc ions were impregnated on Sal-MCM-3 and Sal-MCM-9. Then, Zn-Sal-MCM-3 and Zn-Sal-MCM-9 were calcined to obtain nano-zinc oxide loaded on mesoporous silica (ZnO-MCM-3 and ZnO-MCM-9). The material structures were systematically studied by Fourier transform infrared spectroscopy (FTIR), N2 adsorption/desorption measurements, X-ray powder diffraction (XRD), zeta potential, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), ultraviolet diffused reflectance spectrum (UV-vis DRS), and thermogravimetry (TGA). Methyl orange (MO) was used to investigate the photocatalysis behavior of ZnO-MCM-3 and ZnO-MCM-9. The results confirmed that nano ZnO was loaded in the channels as well as the outside surface of mesoporous silica (MCM-41). The modification of salicylaldimine helped MCM-41 to load more nano ZnO on MCM-41. When the modification amount of salicylaldimine was one-ninth and one-third of the mass of the silicon source, respectively, the load of nano ZnO on ZnO-MCM-9 and ZnO-MCM-3 had atomic concentrations of 1.27 and 2.03, respectively. ZnO loaded on ZnO-MCM-9 had a wurtzite structure, while ZnO loaded on ZnO-MCM-3 was not in the same crystalline group. The blocking effect caused by nano ZnO in the channels reduced the orderliness of MCM-41. The photodegradation of MO can be divided in two processes, which are mainly controlled by the surface areas of ZnO-MCM and the loading amount of nano ZnO, respectively. The pseudo-first-order model was more suitable for the photodegradation process. Full article
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Open AccessArticle High-Switching-Ratio Photodetectors Based on Perovskite CH3NH3PbI3 Nanowires
Nanomaterials 2018, 8(5), 318; https://doi.org/10.3390/nano8050318
Received: 16 April 2018 / Revised: 1 May 2018 / Accepted: 2 May 2018 / Published: 10 May 2018
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Abstract
Hybrid organic-inorganic perovskite materials have attracted extensive attention due to their impressive performance in photovoltaic devices. One-dimensional perovskite CH3NH3PbI3 nanomaterials, possessing unique structural features such as large surface-to-volume ratio, anisotropic geometry and quantum confinement, may have excellent optoelectronic
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Hybrid organic-inorganic perovskite materials have attracted extensive attention due to their impressive performance in photovoltaic devices. One-dimensional perovskite CH3NH3PbI3 nanomaterials, possessing unique structural features such as large surface-to-volume ratio, anisotropic geometry and quantum confinement, may have excellent optoelectronic properties, which could be utilized to fabricate high-performance photodetectors. However, in comparison to CH3NH3PbI3 thin films, reports on the fabrication of CH3NH3PbI3 nanowires for optoelectrical application are rather limited. Herein, a two-step spin-coating process has been utilized to fabricate pure-phase and single-crystalline CH3NH3PbI3 nanowires on a substrate without mesoporous TiO2 or Al2O3. The size and density of CH3NH3PbI3 nanowires can be easily controlled by changing the PbI2 precursor concentration. The as-prepared CH3NH3PbI3 nanowires are utilized to fabricate photodetectors, which exhibit a fairly high switching ratio of ~600, a responsivity of 55 mA/W, and a normalized detectivity of 0.5 × 1011 jones under 532 nm light illumination (40 mW/cm2) at a very low bias voltage of 0.1 V. The as-prepared perovskite CH3NH3PbI3 nanowires with excellent optoelectronic properties are regarded to be a potential candidate for high-performance photodetector application. Full article
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Open AccessArticle Effect of Phenolic Compounds on the Synthesis of Gold Nanoparticles and its Catalytic Activity in the Reduction of Nitro Compounds
Nanomaterials 2018, 8(5), 320; https://doi.org/10.3390/nano8050320
Received: 17 April 2018 / Revised: 5 May 2018 / Accepted: 8 May 2018 / Published: 10 May 2018
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Abstract
Gold nanoparticles (AuNPs) were prepared using an eco-friendly approach in a single step by reduction of HAuCl4 with polyphenols from tea extracts, which act as both reducing and capping agents. The obtained AuNPs were characterized by scanning electron microscopy (SEM), transmission electron
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Gold nanoparticles (AuNPs) were prepared using an eco-friendly approach in a single step by reduction of HAuCl4 with polyphenols from tea extracts, which act as both reducing and capping agents. The obtained AuNPs were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet–visible spectroscopy (UV–vis), and X-ray photoelectron spectroscopy (XPS). They act as highly efficient catalysts in the reduction of various aromatic nitro compounds in aqueous solution. The effects of a variety of factors (e.g., reaction time, type and amount of reducing agent, shape, size, or amount of AuNPs) were studied towards the optimization of the processes. The total polyphenol content (TPC) was determined before and after the catalytic reaction and the results are discussed in terms of the tea extract percentage, the size of the AuNPs, and their catalytic activity. The reusability of the AuNP catalyst in the reduction of 4-nitrophenol was also tested. The reactions follow pseudo first-order kinetics. Full article
(This article belongs to the Special Issue Organic-Inorganic Hybrid Nanomaterials)
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Open AccessCommunication Ambient-Stable and Durable Conductive Ag-Nanowire-Network 2-D Films Decorated with a Ti Layer
Nanomaterials 2018, 8(5), 321; https://doi.org/10.3390/nano8050321
Received: 13 April 2018 / Revised: 2 May 2018 / Accepted: 8 May 2018 / Published: 11 May 2018
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Abstract
Highly stable and durable conductive silver nanowire (Ag NW) network electrode films were prepared through decoration with a 5-nm-thick Ti layer. The Ag NW network 2-D films showed sheet resistance values as low as 32 ohm/sq at 88% transparency when decorated with Ti.
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Highly stable and durable conductive silver nanowire (Ag NW) network electrode films were prepared through decoration with a 5-nm-thick Ti layer. The Ag NW network 2-D films showed sheet resistance values as low as 32 ohm/sq at 88% transparency when decorated with Ti. These 2-D films exhibited a 30% increase in electrical conductivity while maintaining good stability of the films through enhanced resistance to moisture and oxygen penetration as a result of the protective effect of the Ti layer. Full article
(This article belongs to the Special Issue Preparation and Application of Hybrid Nanomaterials)
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Open AccessArticle Drug Delivery System for Emodin Based on Mesoporous Silica SBA-15
Nanomaterials 2018, 8(5), 322; https://doi.org/10.3390/nano8050322
Received: 7 March 2018 / Revised: 4 May 2018 / Accepted: 7 May 2018 / Published: 12 May 2018
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Abstract
In this study mesoporous silica SBA-15 was evaluated as a vehicle for the transport of cytotoxic natural product emodin (EO). SBA-15 was loaded with different quantities of EO (SBA-15|EO1–SBA-15|EO5: 8–36%) and characterized by traditional methods. Several parameters (stabilities) and the in vitro behavior
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In this study mesoporous silica SBA-15 was evaluated as a vehicle for the transport of cytotoxic natural product emodin (EO). SBA-15 was loaded with different quantities of EO (SBA-15|EO1–SBA-15|EO5: 8–36%) and characterized by traditional methods. Several parameters (stabilities) and the in vitro behavior on tumor cell lines (melanoma A375, B16 and B16F10) were investigated. SBA-15 suppresses EO release in extremely acidic milieu, pointing out that EO will not be discharged in the stomach. Furthermore, SBA-15 protects EO from photodecomposition. In vitro studies showed a dose dependent decrease of cellular viability which is directly correlated with an increasing amount of EO in SBA-15 for up to 27% of EO, while a constant activity for 32% and 36% of EO in SBA-15 was observed. Additionally, SBA-15 loaded with EO (SBA-15|EO3) does not disturb viability of peritoneal macrophages. SBA-15|EO3 causes inhibition of tumor cell proliferation and triggers apoptosis, connected with caspase activation, upregulation of Bax, as well as Bcl-2 and Bim downregulation along with amplification of poly-(ADP-ribose)-polymerase (PARP) cleavage fragment. Thus, the mesoporous SBA-15 is a promising carrier of the water-insoluble drug emodin. Full article
(This article belongs to the Special Issue Pharmaceutical Nanotechnology)
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Open AccessArticle ZnO/CuO/M (M = Ag, Au) Hierarchical Nanostructure by Successive Photoreduction Process for Solar Hydrogen Generation
Nanomaterials 2018, 8(5), 323; https://doi.org/10.3390/nano8050323
Received: 17 March 2018 / Revised: 10 May 2018 / Accepted: 10 May 2018 / Published: 12 May 2018
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Abstract
To date, solar energy generation devices have been widely studied to meet a clean and sustainable energy source. Among them, water splitting photoelectrochemical cell is regarded as a promising energy generation way for splitting water molecules and generating hydrogen by sunlight. While many
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To date, solar energy generation devices have been widely studied to meet a clean and sustainable energy source. Among them, water splitting photoelectrochemical cell is regarded as a promising energy generation way for splitting water molecules and generating hydrogen by sunlight. While many nanostructured metal oxides are considered as a candidate, most of them have an improper bandgap structure lowering energy transition efficiency. Herein, we introduce a novel wet-based, successive photoreduction process that can improve charge transfer efficiency by surface plasmon effect for a solar-driven water splitting device. The proposed process enables to fabricate ZnO/CuO/Ag or ZnO/CuO/Au hierarchical nanostructure, having an enhanced electrical, optical, photoelectrochemical property. The fabricated hierarchical nanostructures are demonstrated as a photocathode in the photoelectrochemical cell and characterized by using various analytic tools. Full article
(This article belongs to the Special Issue Nanomaterials for Renewable and Sustainable Energy)
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Open AccessArticle Biomedical Potential of Ultrafine Ag Nanoparticles Coated on Poly (Gamma-Glutamic Acid) Hydrogel with Special Reference to Wound Healing
Nanomaterials 2018, 8(5), 324; https://doi.org/10.3390/nano8050324
Received: 13 April 2018 / Revised: 28 April 2018 / Accepted: 7 May 2018 / Published: 14 May 2018
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Abstract
In wound care management, the prevention of wound infection and the retention of an appropriate level of moisture are two major challenges. Therefore, designing an excellent antibacterial hydrogel with a suitable water-adsorbing capacity is very important to improve the development of wound dressings.
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In wound care management, the prevention of wound infection and the retention of an appropriate level of moisture are two major challenges. Therefore, designing an excellent antibacterial hydrogel with a suitable water-adsorbing capacity is very important to improve the development of wound dressings. In this paper, a novel silver nanoparticles/poly (gamma-glutamic acid) (γ-PGA) composite dressing was prepared for biomedical applications. The promoted wound-healing ability of the hydrogels were systematically evaluated with the aim of attaining a novel and effective wound dressing. A diffusion study showed that hydrogels can continuously release antibacterial factors (Ag). Hydrogels contain a high percentage of water, providing an ideal moist environment for tissue regeneration, while also preventing contraction of the wound. Moreover, an in vivo, wound-healing model evaluation of artificial wounds in mice indicated that silver/γ-PGA hydrogels could significantly promote wound healing. Histological examination revealed that hydrogels can successfully help to reconstruct intact epidermis and collagen deposition during 14 days of impaired wound healing. Overall, this research could shed new light on the design of antibacterial silver/γ-PGA hydrogels with potential applications in wound dressing. Full article
(This article belongs to the Special Issue Nanoscale Materials and Technologies in Tissue Engineering)
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Open AccessArticle Borylation of α,β-Unsaturated Acceptors by Chitosan Composite Film Supported Copper Nanoparticles
Nanomaterials 2018, 8(5), 326; https://doi.org/10.3390/nano8050326
Received: 30 April 2018 / Revised: 10 May 2018 / Accepted: 11 May 2018 / Published: 14 May 2018
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Abstract
We describe here the preparation of copper nanoparticles stabilized on a chitosan/poly (vinyl alcohol) composite film. This material could catalyze the borylation of α,β-unsaturated acceptors in aqueous media under mild conditions. The corresponding organoboron compounds as well as their converted β-hydroxyl products were
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We describe here the preparation of copper nanoparticles stabilized on a chitosan/poly (vinyl alcohol) composite film. This material could catalyze the borylation of α,β-unsaturated acceptors in aqueous media under mild conditions. The corresponding organoboron compounds as well as their converted β-hydroxyl products were all obtained in good to excellent yields. It is noteworthy that this catalyst of copper nanoparticles can be easily recycled eight times and remained catalytically reactive. This newly developed methodology provides an efficient and sustainable pathway for the synthesis of organoboron compounds and application of copper nanoparticles. Full article
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Open AccessArticle An Antimicrobial Peptide-Loaded Gelatin/Chitosan Nanofibrous Membrane Fabricated by Sequential Layer-by-Layer Electrospinning and Electrospraying Techniques
Nanomaterials 2018, 8(5), 327; https://doi.org/10.3390/nano8050327
Received: 25 February 2018 / Revised: 22 April 2018 / Accepted: 4 May 2018 / Published: 14 May 2018
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Abstract
Guided bone regeneration (GBR) technique is widely used in the treatment of bone defects caused by peri-implantitis, periodontal disease, etc. However, the GBR membranes commonly used in clinical treatments currently have no antibacterial activity. Therefore, in this study, sequential layer-by-layer electrospinning and electrospraying
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Guided bone regeneration (GBR) technique is widely used in the treatment of bone defects caused by peri-implantitis, periodontal disease, etc. However, the GBR membranes commonly used in clinical treatments currently have no antibacterial activity. Therefore, in this study, sequential layer-by-layer electrospinning and electrospraying techniques were utilized to prepare a gelatin (Gln) and chitosan (CS) composite GBR membrane containing hydroxyapatite nanoparticles (nHAp) and antimicrobial peptide (Pac-525)-loaded PLGA microspheres (AMP@PLGA-MS), which was supposed to have osteogenic and antibacterial activities. The scanning electron microscope (SEM) observation showed that the morphology of the nanofibers and microspheres could be successfully produced. The diameters of the electrospun fibers with and without nHAp were 359 ± 174 nm and 409 ± 197 nm, respectively, and the mechanical properties of the membrane were measured according to the tensile stress-strain curve. Both the involvement of nHAp and the chemical crosslinking were able to enhance their tensile strength. In vitro cell culture of rat bone marrow mesenchymal stem cells (rBMSCs) indicated that the Gln/CS composite membrane had an ideal biocompatibility with good cell adhesion, spreading, and proliferation. In addition, the Gln/CS membrane containing nHAp could promote osteogenic differentiation of rBMSCs. Furthermore, according to the in vitro drug release assay and antibacterial experiments, the composite GBR membrane containing AMP@PLGA-MS exhibited a long-term sustained release of Pac-525, which had bactericidal activity within one week and antibacterial activity for up to one month against two kinds of bacteria, S. aureus and E. coli. Our results suggest that the antimicrobial peptide-loaded Gln/CS composite membrane (AMP@PLGA-MS@Gln/CS/nHAp) has a great promise in bone generation-related applications for the unique functions of guiding bone regeneration and inhibiting bacterial infection as well. Full article
(This article belongs to the Special Issue The Fabrication and Application of Nanofibers)
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Open AccessArticle Highly Efficient, Low-Cost, and Magnetically Recoverable FePt–Ag Nanocatalysts: Towards Green Reduction of Organic Dyes
Nanomaterials 2018, 8(5), 329; https://doi.org/10.3390/nano8050329
Received: 1 April 2018 / Revised: 11 May 2018 / Accepted: 11 May 2018 / Published: 14 May 2018
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Abstract
Nowadays, synthetic organic dyes and pigments discharged from numerous industries are causing unprecedentedly severe water environmental pollution, and conventional water treatment processes are hindered due to the corresponding sophisticated aromatic structures, hydrophilic nature, and high stability against light, temperature, etc. Herein, we report
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Nowadays, synthetic organic dyes and pigments discharged from numerous industries are causing unprecedentedly severe water environmental pollution, and conventional water treatment processes are hindered due to the corresponding sophisticated aromatic structures, hydrophilic nature, and high stability against light, temperature, etc. Herein, we report an efficient fabrication strategy to develop a new type of highly efficient, low-cost, and magnetically recoverable nanocatalyst, i.e., FePt–Ag nanocomposites, for the reduction of methyl orange (MO) and rhodamine B (RhB), by a facile seed deposition process. X-ray diffraction results elaborate that the as-synthesized FePt–Ag nanocomposites are pure disordered face-centered cubic phase. Transmission electron microscopy studies demonstrate that the amount of Ag seeds deposited onto the surfaces of FePt nanocrystals increases when increasing the additive amount of silver colloids. The linear correlation of the MO and RhB concentration versus reaction time catalyzed by FePt–Ag nanocatalysts is in line with pseudo-first-order kinetics. The reduction rate constants of MO and RhB increase with the increase of the amount of Ag seeds. FePt–Ag nanocomposites show good separation ability and reusability, and could be repeatedly applied for nearly complete reduction of MO and RhB for at least six successive cycles. Such cost-effective and recyclable nanocatalysts provide a new material family for use in environmental protection applications. Full article
(This article belongs to the Special Issue Alleviating Climate Change and Pollution with Nanomaterials)
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Open AccessArticle Enhanced Photocatalytic Activity toward Organic Pollutants Degradation and Mechanism Insight of Novel CQDs/Bi2O2CO3 Composite
Nanomaterials 2018, 8(5), 330; https://doi.org/10.3390/nano8050330
Received: 21 February 2018 / Revised: 10 May 2018 / Accepted: 10 May 2018 / Published: 15 May 2018
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Abstract
Novel carbon quantum dots (CQDs) modified with Bi2O2CO3 (CQDs/Bi2O2CO3) were prepared using a simple dynamic-adsorption precipitation method. X-ray diffractometry (XRD), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), and scanning electron
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Novel carbon quantum dots (CQDs) modified with Bi2O2CO3 (CQDs/Bi2O2CO3) were prepared using a simple dynamic-adsorption precipitation method. X-ray diffractometry (XRD), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), and scanning electron microscopy (SEM) were used to test the material composition, structure, and band structures of the as-prepared samples. Methylene blue (MB) and colorless phenol, as target organic pollutants, were used to evaluate the photocatalytic performance of the CQDs/Bi2O2CO3 hybrid materials under visible light irradiation. Experimental investigation shows that 2–5 nm CQDs were uniformly decorated on the surface of Bi2O2CO3; CQDs/Bi2O2CO3 possess an efficient photocatalytic performance, and the organic matter removal rate of methylene blue and phenol can reach up to 94.45% and 61.46% respectively, within 2 h. In addition, the degradation analysis of phenol by high performance liquid chromatography (HPLC) proved that there are no other impurities in the degradation process. Photoelectrochemical testing proved that the introduction of CQDs (electron acceptor) effectively suppresses the recombination of e-h+, and promotes charge transfer. Quenching experiments and electron spin resonance (ESR) suggested that ·OH, h+, and ·O2 were involved in the photocatalytic degradation process. These results suggested that the up-conversion function of CQDs could improve the electron transfer and light absorption ability of photocatalysts and ·O2 formation. Furthermore, the up-conversion function of CQDs would help maintain photocatalytic stability. Finally, the photocatalytic degradation mechanism was proposed according to the above experimental result. Full article
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Open AccessArticle Simple, Low-Cost Fabrication of Highly Uniform and Reproducible SERS Substrates Composed of Ag–Pt Nanoparticles
Nanomaterials 2018, 8(5), 331; https://doi.org/10.3390/nano8050331
Received: 20 March 2018 / Revised: 2 May 2018 / Accepted: 10 May 2018 / Published: 15 May 2018
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Abstract
Ag–Pt nanoparticles, grafted on Ge wafer, were synthesized by the galvanic replacement reaction based on their different potentials. Detailed characterization through scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS) and X-ray photo-elelctron spectroscopy (XPS) proved that Ag–Pt nanoparticles are composed of large Ag
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Ag–Pt nanoparticles, grafted on Ge wafer, were synthesized by the galvanic replacement reaction based on their different potentials. Detailed characterization through scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS) and X-ray photo-elelctron spectroscopy (XPS) proved that Ag–Pt nanoparticles are composed of large Ag nanoparticles and many small Pt nanoparticles instead of an Ag–Pt alloy. When applied as surface-enhanced Raman scattering (SERS) substrates to detect Rhodamine 6G (1 × 10−8 M) or Crystal violet (1 × 10−7 M) aqueous solution in the line mapping mode, all of the obtained relative standard deviation (RSD) values of the major characteristic peak intensities, calculated from the SERS spectra of 100 serial spots, were less than 10%. The fabrication process of the SERS substrate has excellent uniformity and reproducibility and is simple, low-cost and time-saving, which will benefit studies on the platinum-catalyzed reaction mechanisms in situ and widen the practical application of SERS. Full article
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Open AccessArticle Self-Assembled Ag-Cu2O Nanocomposite Films at Air-Liquid Interfaces for Surface-Enhanced Raman Scattering and Electrochemical Detection of H2O2
Nanomaterials 2018, 8(5), 332; https://doi.org/10.3390/nano8050332
Received: 22 April 2018 / Revised: 8 May 2018 / Accepted: 8 May 2018 / Published: 15 May 2018
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Abstract
We employ a facile and novel route to synthesize multifunctional Ag-Cu2O nanocomposite films through the self-assembly of nanoparticles at an air-liquid interface. In the ethanol-water phase, AgNO3 and Cu(NO3)2 were reduced to Ag-Cu2O nanoparticles by
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We employ a facile and novel route to synthesize multifunctional Ag-Cu2O nanocomposite films through the self-assembly of nanoparticles at an air-liquid interface. In the ethanol-water phase, AgNO3 and Cu(NO3)2 were reduced to Ag-Cu2O nanoparticles by NaBH4 in the presence of cinnamic acid. The Ag-Cu2O nanoparticles were immediately trapped at the air-liquid interface to form two-dimensional nanocomposite films after the reduction reaction was finished. The morphology of the nanocomposite films could be controlled by the systematic regulation of experimental parameters. It was found that the prepared nanocomposite films serving as the substrates exhibited strong surface-enhanced Raman scattering (SERS) activity. 4-aminothiophenol (4-ATP) molecules were used as the test probes to examine the SERS sensitivity of the nanocomposite films. Moreover, the nanocomposite films synthesized by our method showed enhanced electrocatalytic activity towards hydrogen peroxide (H2O2) and therefore could be utilized to fabricate a non-enzymatic electrochemical H2O2 sensor. Full article
(This article belongs to the Special Issue Synthesis, Structure and Applications of 2D Nanomaterials)
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Open AccessArticle High-Efficiency Visible Transmitting Polarizations Devices Based on the GaN Metasurface
Nanomaterials 2018, 8(5), 333; https://doi.org/10.3390/nano8050333
Received: 29 April 2018 / Revised: 9 May 2018 / Accepted: 10 May 2018 / Published: 15 May 2018
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Abstract
Metasurfaces are capable of tailoring the amplitude, phase, and polarization of incident light to design various polarization devices. Here, we propose a metasurface based on the novel dielectric material gallium nitride (GaN) to realize high-efficiency modulation for both of the orthogonal linear polarizations
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Metasurfaces are capable of tailoring the amplitude, phase, and polarization of incident light to design various polarization devices. Here, we propose a metasurface based on the novel dielectric material gallium nitride (GaN) to realize high-efficiency modulation for both of the orthogonal linear polarizations simultaneously in the visible range. Both modulated transmitted phases of the orthogonal linear polarizations can almost span the whole 2π range by tailoring geometric sizes of the GaN nanobricks, while maintaining high values of transmission (almost all over 90%). At the wavelength of 530 nm, we designed and realized the beam splitter and the focusing lenses successfully. To further prove that our proposed method is suitable for arbitrary orthogonal linear polarization, we also designed a three-dimensional (3D) metalens that can simultaneously focus the X-, Y-, 45°, and 135° linear polarizations on spatially symmetric positions, which can be applied to the linear polarization measurement. Our work provides a possible method to achieve high-efficiency multifunctional optical devices in visible light by extending the modulating dimensions. Full article
(This article belongs to the Special Issue Optoelectronic Nanodevices)
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Open AccessArticle An Innovative Porous Nanocomposite Material for the Removal of Phenolic Compounds from Aqueous Solutions
Nanomaterials 2018, 8(5), 334; https://doi.org/10.3390/nano8050334
Received: 3 May 2018 / Revised: 11 May 2018 / Accepted: 14 May 2018 / Published: 16 May 2018
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Abstract
Energy efficient, low-cost, user-friendly, and green methods for the removal of toxic phenolic compounds from aqueous solution are necessary for waste treatment in industrial applications. Herein we present an interesting approach for the utilization of oxidized carbon nanotubes (CNTs) in the removal of
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Energy efficient, low-cost, user-friendly, and green methods for the removal of toxic phenolic compounds from aqueous solution are necessary for waste treatment in industrial applications. Herein we present an interesting approach for the utilization of oxidized carbon nanotubes (CNTs) in the removal of phenolic compounds from aqueous solution. Dried pristine CNTs were stably incorporated in a solid porous support of polydimethylsiloxane (PDMS) facilitating the handling during both oxidation process of the nanomaterial and uptake of phenolic compounds, and enabling their safe disposal, avoiding expensive post-treatment processes. The adsorption studies indicated that the materials can efficiently remove phenolic compounds from water with different affinities towards different phenolic compounds. Furthermore, the adsorption kinetics and isotherms were studied in detail. The experimental data of adsorption fitted well with Langmuir and Freundlich isotherms, and pseudo-second-order kinetics, and the results indicated that the adsorption process was controlled by a two-step intraparticle diffusion model. The incorporation of CNTs in polymeric matrices did not affect their functionality in phenol uptake. The material was also successfully used for the removal of phenolic compounds from agricultural waste, suggesting its possible application in the treatment of wastewater. Moreover, the surface of the material could be regenerated, decreasing treatment costs. Full article
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Open AccessArticle High Performance of Supercapacitor from PEDOT:PSS Electrode and Redox Iodide Ion Electrolyte
Nanomaterials 2018, 8(5), 335; https://doi.org/10.3390/nano8050335
Received: 18 April 2018 / Revised: 5 May 2018 / Accepted: 9 May 2018 / Published: 16 May 2018
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Abstract
Insufficient energy density and poor cyclic stability is still challenge for conductive polymer-based supercapacitor. Herein, high performance electrochemical system has been assembled by combining poly (3,4-ethylenedioxythiophene) (PEDOT):poly (styrene sulfonate) (PSS) redox electrode and potassium iodide redox electrolyte, which provide the maximum specific capacity
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Insufficient energy density and poor cyclic stability is still challenge for conductive polymer-based supercapacitor. Herein, high performance electrochemical system has been assembled by combining poly (3,4-ethylenedioxythiophene) (PEDOT):poly (styrene sulfonate) (PSS) redox electrode and potassium iodide redox electrolyte, which provide the maximum specific capacity of 51.3 mAh/g and the retention of specific capacity of 87.6% after 3000 cycles due to the synergic effect through a simultaneous redox reaction both in electrode and electrolyte, as well as the catalytic activity for reduction of triiodide of the PEDOT:PSS. Full article
(This article belongs to the Special Issue Three-dimensional Nanomaterials for Energy Storage and Conversions)
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Open AccessArticle Fabrication and Characterization of Nanoenergetic Hollow Spherical Hexanitrostibene (HNS) Derivatives
Nanomaterials 2018, 8(5), 336; https://doi.org/10.3390/nano8050336
Received: 28 April 2018 / Revised: 13 May 2018 / Accepted: 14 May 2018 / Published: 16 May 2018
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Abstract
The spherization of nanoenergetic materials is the best way to improve the sensitivity and increase loading densities and detonation properties for weapons and ammunition, but the preparation of spherical nanoenergetic materials with high regularization, uniform size and monodispersity is still a challenge. In
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The spherization of nanoenergetic materials is the best way to improve the sensitivity and increase loading densities and detonation properties for weapons and ammunition, but the preparation of spherical nanoenergetic materials with high regularization, uniform size and monodispersity is still a challenge. In this paper, nanoenergetic hollow spherical hexanitrostibene (HNS) derivatives were fabricated via a one-pot copolymerization strategy, which is based on the reaction of HNS and piperazine in acetonitrile solution. Characterization results indicated the as-prepared reaction nanoenergetic products were HNS-derived oligomers, where a free radical copolymerization reaction process was inferred. The hollow sphere structure of the HNS derivatives was characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM), and synchrotron radiation X-ray imaging technology. The properties of the nanoenergetic hollow spherical derivatives, including thermal decomposition and sensitivity are discussed in detail. Sensitivity studies showed that the nanoenergetic derivatives exhibited lower impact, friction and spark sensitivity than raw HNS. Thermogravimetric-differential scanning calorimeter (TG-DSC) results showed that continuous exothermic decomposition occurred in the whole temperature range, which indicated that nanoenergetic derivatives have a unique role in thermal applications. Therefore, nanoenergetic hollow spherical HNS derivatives could provide a new way to modify the properties of certain energetic compounds and fabricate spherical nanomaterials to improve the charge configuration. Full article
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Open AccessArticle Effective NiMn Nanoparticles-Functionalized Carbon Felt as an Effective Anode for Direct Urea Fuel Cells
Nanomaterials 2018, 8(5), 338; https://doi.org/10.3390/nano8050338
Received: 16 March 2018 / Revised: 7 May 2018 / Accepted: 14 May 2018 / Published: 16 May 2018
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Abstract
The internal resistances of fuel cells strongly affect the generated power. Basically, in the fuel cell, the anode can be prepared by deposition of a film from the functional electrocatalyst on a proper gas diffusion layer. Accordingly, an interfacial resistance for the electron
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The internal resistances of fuel cells strongly affect the generated power. Basically, in the fuel cell, the anode can be prepared by deposition of a film from the functional electrocatalyst on a proper gas diffusion layer. Accordingly, an interfacial resistance for the electron transport is created between the two layers. Electrocatalyst-functionalized gas diffusion layer (GDL) can distinctly reduce the interfacial resistance between the catalyst layer and the GDL. In this study, NiMn nanoparticles-decorated carbon felt is introduced as functionalized GDL to be exploited as a ready-made anode in a direct urea fuel cell. The proposed treated GDL was prepared by calcination of nickel acetate/manganese acetate-loaded carbon felt under an argon atmosphere at 850 °C. The physiochemical characterizations confirmed complete reduction for the utilized precursors and deposition of pristine NiMn nanoparticles on the carbon felt fiber. In passive direct urea fuel cells, investigation the performance of the functionalized GDLs indicated that the composition of the metal nanoparticles has to be optimized as the GDL obtained from 40 wt % manganese acetate reveals the maximum generated power density; 36 mW/m2 at room temperature and 0.5 M urea solution. Moreover, the electrochemical measurements proved that low urea solution concentration is preferred as utilizing 0.5 M solution resulted into generating higher power compared to 1.0 and 2.0 M solution. Overall, this study opens a new avenue toward functionalization of the GDL as a novel strategy to overcome the interfacial resistance between the electrocatalyst and the GDL. Full article
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Open AccessArticle pH-Responsive Mercaptoundecanoic Acid Functionalized Gold Nanoparticles and Applications in Catalysis
Nanomaterials 2018, 8(5), 339; https://doi.org/10.3390/nano8050339
Received: 18 April 2018 / Revised: 14 May 2018 / Accepted: 15 May 2018 / Published: 17 May 2018
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Abstract
Mercaptoundecanoic acid (MUA) functionalized gold nanoparticles (AuNP-MUA) were synthesized and demonstrated to possess pH-triggered aggregation and re-dispersion, as well as the capability of phase transfer between aqueous and organic phases in response to changes in pH. The pH of aggregation for AuNP-MUA is
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Mercaptoundecanoic acid (MUA) functionalized gold nanoparticles (AuNP-MUA) were synthesized and demonstrated to possess pH-triggered aggregation and re-dispersion, as well as the capability of phase transfer between aqueous and organic phases in response to changes in pH. The pH of aggregation for AuNP-MUA is consistent with the pKa of MUA (pH ~4) in solution, while AuNP-MUA phase transition between aqueous and organic phases occurs at pH ~9. The ion pair formation between the amine group in octadecylamine (ODA), the carboxylate group in MUA, and the hydrophobic alkyl chain of ODA facilitates the phase transfer of AuNP-MUA into an organic medium. The AuNP-MUA were investigated as a reusable catalyst in the catalytic reduction of 4-nitrophenol by borohydride—a model reaction for AuNPs. It was determined that 100% MUA surface coverage completely inhibits the catalytic activity of AuNPs. Decreasing the surface coverage was shown to increase catalytic activity, but this decrease also leads to decreased colloidal stability, recoverability, and reusability in subsequent reactions. At 60% MUA surface coverage, colloidal stability and catalytic activity were achieved, but the surface coverage was insufficient to enable redispersion following pH-induced recovery. A balance between AuNP colloidal stability, recoverability, and catalytic activity with reusability was achieved at 90% MUA surface coverage. The AuNP-MUA catalyst can also be recovered at different pH ranges depending on the recovery method employed. At pH ~4, protonation of the MUA results in reduced surface charge and aggregation. At pH ~9, ODA will form an ion-pair with the MUA and induce phase transfer into an immiscible organic phase. Both the pH-triggered aggregation/re-dispersion and aqueous/organic phase transfer methods were employed for catalyst recovery and reuse in subsequent reactions. The ability to recover and reuse the AuNP-MUA catalyst by two different methods and different pH regimes is significant, based on the fact that nanoparticle-catalyzed reactions may occur under different pH conditions. Full article
(This article belongs to the Special Issue Synthesis of Ligand-Capped Nanoparticles for Catalysis)
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Open AccessArticle Wetting Behaviors of a Nano-Droplet on a Rough Solid Substrate under Perpendicular Electric Field
Nanomaterials 2018, 8(5), 340; https://doi.org/10.3390/nano8050340
Received: 27 April 2018 / Revised: 14 May 2018 / Accepted: 15 May 2018 / Published: 17 May 2018
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Abstract
Molecular dynamic simulations were adopted to study the wetting properties of nanoscale droplets on rough silicon solid substrate subject to perpendicular electric fields. The effect of roughness factor and electric field strength on the static and dynamic wetting behaviors of a nano-droplet on
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Molecular dynamic simulations were adopted to study the wetting properties of nanoscale droplets on rough silicon solid substrate subject to perpendicular electric fields. The effect of roughness factor and electric field strength on the static and dynamic wetting behaviors of a nano-droplet on a solid surface was investigated at the molecular level. Results show that the static contact angle tends to decrease slightly and show small difference with the increase of roughness factor, while it shows an obvious increase for the ramp-shaped surface because the appearing bottom space reduces the wettability of solid surface. Additionally, under the electric field, a nano-droplet was elongated in the field direction and the equilibrium contact angle increases with the increase of electric field strength. The nano-droplet was completely stretched to be column-shaped at a threshold value of the field. Besides, accompanied by the shape variation of water droplets, the molecular dipole orientations of water molecules experience a remarkable change from a random disordered distribution to an ordered profile because of the realignment of water molecules induced by electric fields. Full article
(This article belongs to the Special Issue Wetting of Nanostructured Materials)
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Open AccessArticle The Effect of Light Intensity, Temperature, and Oxygen Pressure on the Photo-Oxidation Rate of Bare PbS Quantum Dots
Nanomaterials 2018, 8(5), 341; https://doi.org/10.3390/nano8050341 (registering DOI)
Received: 17 April 2018 / Revised: 11 May 2018 / Accepted: 14 May 2018 / Published: 18 May 2018
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Abstract
The oxidation speed of PbS quantum dots has been a subject of controversy for some time. In this study, we reveal the precise functional form of the oxidation rate constant for bare quantum dots through analysis of their photoluminescence as a function of
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The oxidation speed of PbS quantum dots has been a subject of controversy for some time. In this study, we reveal the precise functional form of the oxidation rate constant for bare quantum dots through analysis of their photoluminescence as a function of temperature, oxygen pressure, and excitation-laser intensity. The combined effect of these factors results in a reduced energy barrier that allows the oxidation to proceed at a high rate. Each absorbed photon is found to have a 10−8 probability of oxidizing a PbS atomic pair. This highlights the importance of photo-excitation on the speed of the oxidation process, even at low illumination conditions. The procedure used here may set up a quantitative standard useful for characterizing the stability of quantum dots coated with ligands/linkers, and to compare different protection schemes in a fair quantitative way. Full article
(This article belongs to the Special Issue Nanomaterials for Renewable and Sustainable Energy)
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Open AccessArticle Effect of Microwave Radiation Power on the Size of Aggregates of ZnO NPs Prepared Using Microwave Solvothermal Synthesis
Nanomaterials 2018, 8(5), 343; https://doi.org/10.3390/nano8050343 (registering DOI)
Received: 26 April 2018 / Revised: 14 May 2018 / Accepted: 15 May 2018 / Published: 18 May 2018
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