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Nanomaterials, Volume 7, Issue 10 (October 2017)

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Cover Story The most efficient removal of organic pollutants is achieved with enzymatic reagents grafted on [...] Read more.
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Open AccessArticle Synthesis of Multi-Walled Carbon Nanotubes from Plastic Waste Using a Stainless-Steel CVD Reactor as Catalyst
Nanomaterials 2017, 7(10), 284; doi:10.3390/nano7100284
Received: 11 August 2017 / Revised: 14 September 2017 / Accepted: 18 September 2017 / Published: 22 September 2017
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Abstract
The disposal of non-biodegradable plastic waste without further upgrading/downgrading is not environmentally acceptable and many methods to overcome the problem have been proposed. Herein we indicate a simple method to make high-value nanomaterials from plastic waste as a partial solution to the environmental
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The disposal of non-biodegradable plastic waste without further upgrading/downgrading is not environmentally acceptable and many methods to overcome the problem have been proposed. Herein we indicate a simple method to make high-value nanomaterials from plastic waste as a partial solution to the environmental problem. Laboratory-based waste centrifuge tubes made of polypropylene were chosen as a carbon source to show the process principle. In the process, multi-walled carbon nanotubes (MWCNTs) were synthesized from plastic waste in a two-stage stainless steel 316 (SS 316) metal tube that acted as both reactor vessel and catalyst. The steel reactor contains Fe (and Ni, and various alloys), which act as the catalyst for the carbon conversion process. The reaction and products were studied using electron probe microanalysis, thermogravimetric analysis, Raman spectroscopy and transmission electron microscopy and scanning electron microscopy. Optimization studies to determine the effect of different parameters on the process showed that the highest yield and most graphitized MWCNTs were formed at 900 °C under the reaction conditions used (yield 42%; Raman ID/IG ratio = 0.48). The high quality and high yield of the MWCNTs that were produced in a flow reactor from plastic waste using a two stage SS 316 chemical vapor deposition (CVD) furnace did not require the use of an added catalyst. Full article
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Open AccessArticle Synthesis and Enhanced Ethanol Gas Sensing Properties of the g-C3N4 Nanosheets-Decorated Tin Oxide Flower-Like Nanorods Composite
Nanomaterials 2017, 7(10), 285; doi:10.3390/nano7100285
Received: 23 August 2017 / Revised: 16 September 2017 / Accepted: 18 September 2017 / Published: 22 September 2017
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Abstract
Flower-like SnO2/g-C3N4 nanocomposites were synthesized via a facile hydrothermal method by using SnCl4·5H2O and urea as the precursor. The structure and morphology of the as-synthesized samples were characterized by using the X-ray powder diffraction
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Flower-like SnO2/g-C3N4 nanocomposites were synthesized via a facile hydrothermal method by using SnCl4·5H2O and urea as the precursor. The structure and morphology of the as-synthesized samples were characterized by using the X-ray powder diffraction (XRD), electron microscopy (FESEM and TEM), and Fourier transform infrared spectrometer (FT-IR) techniques. SnO2 displays the unique 3D flower-like microstructure assembled with many uniform nanorods with the lengths and diameters of about 400–600 nm and 50–100 nm, respectively. For the SnO2/g-C3N4 composites, SnO2 flower-like nanorods were coupled by a lamellar structure 2D g-C3N4. Gas sensing performance test results indicated that the response of the sensor based on 7 wt. % 2D g-C3N4-decorated SnO2 composite to 500 ppm ethanol vapor was 150 at 340 °C, which was 3.5 times higher than that of the pure flower-like SnO2 nanorods-based sensor. The gas sensing mechanism of the g-C3N4nanosheets-decorated SnO2 flower-like nanorods was discussed in relation to the heterojunction structure between g-C3N4 and SnO2. Full article
(This article belongs to the Special Issue Preparation and Application of Hybrid Nanomaterials)
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Open AccessArticle A Spectral Probe for Detection of Aluminum (III) Ions Using Surface Functionalized Gold Nanoparticles
Nanomaterials 2017, 7(10), 287; doi:10.3390/nano7100287
Received: 5 August 2017 / Revised: 17 September 2017 / Accepted: 19 September 2017 / Published: 22 September 2017
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Abstract
A simple green route has been developed for the synthesis of casein peptide functionalized gold nanoparticles (AuNPs), in which casein peptide acts as a reducing as well as the stabilizing agent. In this report, AuNPs have been characterized on the basis of spectroscopic
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A simple green route has been developed for the synthesis of casein peptide functionalized gold nanoparticles (AuNPs), in which casein peptide acts as a reducing as well as the stabilizing agent. In this report, AuNPs have been characterized on the basis of spectroscopic and microscopic results; which showed selective and sensitive response toward Al3+ in aqueous media, and Al3+ induces aggregation of AuNPs. The sensing study performed for Al3+ revealed that the color change from red to blue was due to a red-shift in the surface plasmon resonance (SPR) band and the formation of aggregated species of AuNPs. The calibration curve determines the detection limit (LOD) for Al3+ about 20 ppb (0.067 μM) is presented using both decrease and increase in absorbance at 530 and 700 nm, respectively. This value is considerably lower than the higher limit allowed for Al3+ in drinking water by the world health organization (WHO) (7.41 μM), representing enough sensitivity to protect water quality. The intensity of the red-shifted band increases with linear pattern upon the interaction with different concentrations of Al3+, thus the possibility of producing unstable AuNPs aggregates. The method is successfully used for the detection of Al3+ in water samples collected from various sources, human urine and ionic drink. The actual response time required for AuNPs is about 1 min, this probe also have several advantages, such as ease of synthesis, functionalization and its use, high sensitivity, and enabling on-site monitoring. Full article
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Open AccessArticle Stealth Biocompatible Si-Based Nanoparticles for Biomedical Applications
Nanomaterials 2017, 7(10), 288; doi:10.3390/nano7100288
Received: 31 August 2017 / Revised: 18 September 2017 / Accepted: 20 September 2017 / Published: 23 September 2017
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Abstract
A challenge regarding the design of nanocarriers for drug delivery is to prevent their recognition by the immune system. To improve the blood residence time and prevent their capture by organs, nanoparticles can be designed with stealth properties using polymeric coating. In this
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A challenge regarding the design of nanocarriers for drug delivery is to prevent their recognition by the immune system. To improve the blood residence time and prevent their capture by organs, nanoparticles can be designed with stealth properties using polymeric coating. In this study, we focused on the influence of surface modification with polyethylene glycol and/or mannose on the stealth behavior of porous silicon nanoparticles (pSiNP, ~200 nm). In vivo biodistribution of pSiNPs formulations were evaluated in mice 5 h after intravenous injection. Results indicated that the distribution in the organs was surface functionalization-dependent. Pristine pSiNPs and PEGylated pSiNPs were distributed mainly in the liver and spleen, while mannose-functionalized pSiNPs escaped capture by the spleen, and had higher blood retention. The most efficient stealth behavior was observed with PEGylated pSiNPs anchored with mannose that were the most excreted in urine at 5 h. The biodegradation kinetics evaluated in vitro were in agreement with these in vivo observations. The biocompatibility of the pristine and functionalized pSiNPs was confirmed in vitro on human cell lines and in vivo by cytotoxic and systemic inflammation investigations, respectively. With their biocompatibility, biodegradability, and stealth properties, the pSiNPs functionalized with mannose and PEG show promising potential for biomedical applications. Full article
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Open AccessArticle Tuning the Electronic Conductivity in Hydrothermally Grown Rutile TiO2 Nanowires: Effect of Heat Treatment in Different Environments
Nanomaterials 2017, 7(10), 289; doi:10.3390/nano7100289
Received: 28 August 2017 / Revised: 13 September 2017 / Accepted: 19 September 2017 / Published: 23 September 2017
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Abstract
Hydrothermally grown rutile TiO2 nanowires are intrinsically full of lattice defects, especially oxygen vacancies. These vacancies have a significant influence on the structural and electronic properties of the nanowires. In this study, we report a post-growth heat treatment in different environments that
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Hydrothermally grown rutile TiO2 nanowires are intrinsically full of lattice defects, especially oxygen vacancies. These vacancies have a significant influence on the structural and electronic properties of the nanowires. In this study, we report a post-growth heat treatment in different environments that allows control of the distribution of these defects inside the nanowire, and thus gives direct access to tuning of the properties of rutile TiO2 nanowires. A detailed transmission electron microscopy study is used to analyze the structural changes inside the nanowires which are correlated to the measured optical and electrical properties. The highly defective as-grown nanowire arrays have a white appearance and show typical semiconducting properties with n-type conductivity, which is related to the high density of oxygen vacancies. Heat treatment in air atmosphere leads to a vacancy condensation and results in nanowires which possess insulating properties, whereas heat treatment in N2 atmosphere leads to nanowire arrays that appear black and show almost metal-like conductivity. We link this high conductivity to a TiO2−x shell which forms during the annealing process due to the slightly reducing N2 environment. Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures)
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Open AccessArticle Practical Liposomal Formulation for Taxanes with Polyethoxylated Castor Oil and Ethanol with Complete Encapsulation Efficiency and High Loading Efficiency
Nanomaterials 2017, 7(10), 290; doi:10.3390/nano7100290
Received: 21 August 2017 / Revised: 13 September 2017 / Accepted: 19 September 2017 / Published: 23 September 2017
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Abstract
Taxanes including paclitaxel and docetaxel are effective anticancer agents preferably sufficient for liposomal drug delivery. However, the encapsulation of these drugs with effective amounts into conventional liposomes is difficult due to their high hydrophobicity. Therefore, an effective encapsulation strategy for liposomal taxanes has
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Taxanes including paclitaxel and docetaxel are effective anticancer agents preferably sufficient for liposomal drug delivery. However, the encapsulation of these drugs with effective amounts into conventional liposomes is difficult due to their high hydrophobicity. Therefore, an effective encapsulation strategy for liposomal taxanes has been eagerly anticipated. In this study, the mixture of polyethoxylated castor oil (Cremophor EL) and ethanol containing phosphate buffered saline termed as CEP was employed as a solvent of the inner hydrophilic core of liposomes where taxanes should be incorporated. Docetaxel-, paclitaxel-, or 7-oxacetylglycosylated paclitaxel-encapsulating liposomes were successfully prepared with almost 100% of encapsulation efficiency and 29.9, 15.4, or 29.1 mol% of loading efficiency, respectively. We then applied the docetaxel-encapsulating liposomes for targeted drug delivery. Docetaxel-encapsulating liposomes were successfully developed HER2-targeted drug delivery by coupling HER2-specific binding peptide on liposome surface. The HER2-targeting liposomes exhibited HER2-specific internalization and enhanced anticancer activity in vitro. Therefore, we propose the sophisticated preparation of liposomal taxanes using CEP as a promising formulation for effective cancer therapies. Full article
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Open AccessArticle Monolayer Colloidal Crystals by Modified Air-Water Interface Self-Assembly Approach
Nanomaterials 2017, 7(10), 291; doi:10.3390/nano7100291
Received: 28 August 2017 / Revised: 19 September 2017 / Accepted: 20 September 2017 / Published: 25 September 2017
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Abstract
Hexagonally ordered arrays of polystyrene (PS) microspheres were prepared by a modified air-water self-assembly method. A detailed analysis of the air-water interface self-assembly process was conducted. Several parameters affect the quality of the monolayer colloidal crystals, i.e., the colloidal microsphere concentration on the
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Hexagonally ordered arrays of polystyrene (PS) microspheres were prepared by a modified air-water self-assembly method. A detailed analysis of the air-water interface self-assembly process was conducted. Several parameters affect the quality of the monolayer colloidal crystals, i.e., the colloidal microsphere concentration on the latex, the surfactant concentration, the polystyrene microsphere diameter, the microsphere polydispersity, and the degree of sphericity of polystyrene microspheres. An abrupt change in surface tension was used to improve the quality of the monolayer colloidal crystal. Three typical microstructures, i.e., a cone, a pillar, and a binary structure were prepared by reactive-ion etching using a high-quality colloidal crystal mask. This study provides insight into the production of microsphere templates with flexible structures for large-area patterned materials. Full article
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Open AccessCommunication Structural Regulation and Electroconductivity Change of Nitrogen-Doping Reduced Graphene Oxide Prepared Using p-Phenylene Diamine as Modifier
Nanomaterials 2017, 7(10), 292; doi:10.3390/nano7100292
Received: 29 August 2017 / Revised: 12 September 2017 / Accepted: 20 September 2017 / Published: 25 September 2017
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Abstract
Using p-phenylene diamine (PPD) as a modifier and nitrogen resource, nitrogen-doping reduced graphene oxide was prepared by one-step refluxing method. The influence of PPD-GO (graphene oxide) mass ratio X on surface functional groups, layer structure, and electroconductivity of nitrogen-doping reduced grapheme oxide
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Using p-phenylene diamine (PPD) as a modifier and nitrogen resource, nitrogen-doping reduced graphene oxide was prepared by one-step refluxing method. The influence of PPD-GO (graphene oxide) mass ratio X on surface functional groups, layer structure, and electroconductivity of nitrogen-doping reduced grapheme oxide (NRGO-X) was investigated by Fourier Transform Infrared Spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), UV-vis absorption spectrum, and electrical measurement. The results showed that GO can be simultaneously reduced and nitrogen-doped by PPD. When PPD-GO mass ratio X ≤ 6, there existed three types of N configurations in NRGO-X, including pyridinic N, pyrrolic N, and graphitic N. However, when X > 6, the pyridinic N disappeared in a six-membered ring. Further, the reduction process of NRGO as well as the nitrogen doping level and type can be regulated by changing the mass ratio X. With the increase of X, the d-spacing of NRGO-X layers increased first and then decreased, while the electrical conductivity increased gradually. Full article
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Open AccessArticle Nanostructured Electrospun Hybrid Graphene/Polyacrylonitrile Yarns
Nanomaterials 2017, 7(10), 293; doi:10.3390/nano7100293
Received: 2 August 2017 / Revised: 21 September 2017 / Accepted: 21 September 2017 / Published: 25 September 2017
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Abstract
Novel nanostructured hybrid electrospun polyacrylonitrile (PAN) yarns with different graphene ratios were prepared using liquid crystal graphene oxide (LCGO) and PAN. It was found that the well-dispersed LCGO were oriented along the fiber axis in an electrified thin liquid jet during electrospinning. The
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Novel nanostructured hybrid electrospun polyacrylonitrile (PAN) yarns with different graphene ratios were prepared using liquid crystal graphene oxide (LCGO) and PAN. It was found that the well-dispersed LCGO were oriented along the fiber axis in an electrified thin liquid jet during electrospinning. The graphene oxide sheets were well dispersed in the polar organic solvent, forming nematic liquid crystals upon increasing concentration. Twisted nanofibers were produced from aligned nanofibrous mats prepared by conventional electrospinning. It was found that the mechanical properties of the twisted nanofiber yarns increased even at very low LCGO loading. This research offers a new approach for the fabrication of continuous, strong, and uniform twisted nanofibers which could show promise in developing a novel carbon fiber precursor. Full article
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Open AccessArticle Carbon Nanohorns Modified with Conjugated Terthienyl/Terthiophene Structures: Additives to Enhance the Performance of Dye-Sensitized Solar Cells
Nanomaterials 2017, 7(10), 294; doi:10.3390/nano7100294
Received: 31 August 2017 / Revised: 15 September 2017 / Accepted: 19 September 2017 / Published: 25 September 2017
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Abstract
A series of carbon nanohorns (CNHs) constituted by the aggregation of about 2000 individual conical graphene tubes (diameters from 2 nm to 5 nm and a length of 40–50 nm) that have been modified with dyes of two, three, or four terthienyl groups
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A series of carbon nanohorns (CNHs) constituted by the aggregation of about 2000 individual conical graphene tubes (diameters from 2 nm to 5 nm and a length of 40–50 nm) that have been modified with dyes of two, three, or four terthienyl groups has been prepared by adsorbing the corresponding dye on the CNH. Persistent inks in o-dichlorobenzene (o-DCB) of these dye-CNH conjugates were obtained by laser irradiation of o-DCB suspensions of the dye-CNH solids. These inks were used in combination or not with N719 dye for the preparation of dye-sensitized solar cells (DSSC) of TiO2. It was measured that the terthienyl dye with the largest conjugation deposited on the CNH additively increased the performance of an analogous TiO2 cell from an efficiency of 4.07% to 6.24%. This result shows the potential of dye-modified CNHs as additives in the construction of more efficient DSSCs. Full article
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Open AccessArticle Structural Distortion in MnO2 Nanosheets and Its Suppression by Cobalt Substitution
Nanomaterials 2017, 7(10), 295; doi:10.3390/nano7100295
Received: 23 August 2017 / Revised: 20 September 2017 / Accepted: 21 September 2017 / Published: 25 September 2017
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Abstract
Co–Mn oxide nanosheets with the chemical composition H0.23Co0.23Mn0.77O2 (C23M77NS) and MnO2 nanosheets (M100NS) were prepared by exfoliation of layer-structured oxides via chemical processing in an aqueous medium. The optical properties of C23M77NS and M100NS were
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Co–Mn oxide nanosheets with the chemical composition H0.23Co0.23Mn0.77O2 (C23M77NS) and MnO2 nanosheets (M100NS) were prepared by exfoliation of layer-structured oxides via chemical processing in an aqueous medium. The optical properties of C23M77NS and M100NS were compared using UV-Vis spectroscopy, and the valence states of Mn and Co and local structures around them were examined using X-ray absorption spectroscopy. M100NS with an average Mn valence of 3.6 exhibits large structural distortion, whereas C23M77NS with an average Mn valence of 4.0 does not exhibit structural distortion. Spontaneous oxidization of Mn occurs during ion-exchange and/or exfoliation into nanosheets. These results have originated the hypothesis that structural distortion determines the valence state of Mn in compounds with CdI2-type-structured MnO2 layers. Full article
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Open AccessArticle Poly-L-arginine Coated Silver Nanoprisms and Their Anti-Bacterial Properties
Nanomaterials 2017, 7(10), 296; doi:10.3390/nano7100296
Received: 26 July 2017 / Revised: 13 September 2017 / Accepted: 22 September 2017 / Published: 27 September 2017
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Abstract
The aim of this study was to test the effect of two different morphologies of silver nanoparticles, spheres, and prisms, on their antibacterial properties when coated with poly-L-arginine (poly-Arg) to enhance the interactions with cells. Silver nanoparticle solutions were characterized by
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The aim of this study was to test the effect of two different morphologies of silver nanoparticles, spheres, and prisms, on their antibacterial properties when coated with poly-L-arginine (poly-Arg) to enhance the interactions with cells. Silver nanoparticle solutions were characterized by UV–visible spectroscopy, transmission electron microscopy, dynamic light scattering, zeta potential, as well as antimicrobial tests. These ultimately showed that a prismatic morphology exhibited stronger antimicrobial effects against Escherichia coli, Pseudomonas aeruginosa and Salmonella enterica. The minimum bactericidal concentration was found to be 0.65 μg/mL in the case of a prismatic AgNP-poly-Arg-PVP (silver nanoparticle-poly-L-arginine-polyvinylpyrrolidone) nanocomposite. The anticancer cell activity of the silver nanoparticles was also studied, where the maximum effect against a HeLa cell line was 80% mortality with a prismatic AgNP-poly-Arg-PVP nanocomposite at a concentration of 11 μg/mL. The antimicrobial activity of these silver nanocomposites demonstrates the potential of such coated silver nanoparticles in the area of nano-medicine. Full article
(This article belongs to the Special Issue Antibacterial Activity of Nanomaterials)
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Open AccessFeature PaperArticle Ionic Liquids as Surfactants for Layered Double Hydroxide Fillers: Effect on the Final Properties of Poly(Butylene Adipate-Co-Terephthalate)
Nanomaterials 2017, 7(10), 297; doi:10.3390/nano7100297
Received: 16 August 2017 / Revised: 23 September 2017 / Accepted: 25 September 2017 / Published: 28 September 2017
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Abstract
In this work, phosphonium ionic liquids (ILs) based on tetra-alkylphosphonium cations combined with carboxylate, phosphate and phosphinate anions, were used for organic modification of layered double hydroxide (LDH). Two different amounts (2 and 5 wt %) of the organically modified LDHs were mixed
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In this work, phosphonium ionic liquids (ILs) based on tetra-alkylphosphonium cations combined with carboxylate, phosphate and phosphinate anions, were used for organic modification of layered double hydroxide (LDH). Two different amounts (2 and 5 wt %) of the organically modified LDHs were mixed with poly(butylene adipate-co-terephthalate) (PBAT) matrix by melt extrusion. All prepared PBAT/IL-modified-LDH composites exhibited increased mechanical properties (20–50% Young’s modulus increase), decreased water vapor permeability (30–50% permeability coefficient reduction), and slight decreased crystallinity (10–30%) compared to the neat PBAT. Full article
(This article belongs to the Special Issue Polymer Nanocomposites)
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Open AccessFeature PaperArticle Sol-Gel Derived Adsorbents with Enzymatic and Complexonate Functions for Complex Water Remediation
Nanomaterials 2017, 7(10), 298; doi:10.3390/nano7100298
Received: 30 August 2017 / Revised: 18 September 2017 / Accepted: 19 September 2017 / Published: 28 September 2017
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Abstract
Sol-gel technology is a versatile tool for preparation of complex silica-based materials with targeting functions for use as adsorbents in water purification. Most efficient removal of organic pollutants is achieved by using enzymatic reagents grafted on nano-carriers. However, enzymes are easily deactivated in
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Sol-gel technology is a versatile tool for preparation of complex silica-based materials with targeting functions for use as adsorbents in water purification. Most efficient removal of organic pollutants is achieved by using enzymatic reagents grafted on nano-carriers. However, enzymes are easily deactivated in the presence of heavy metal cations. In this work, we avoided inactivation of immobilized urease by Cu (II) and Cd (II) ions using magnetic nanoparticles provided with additional complexonate (diethylene triamine pentaacetic acid or DTPA) functions. Obtained nanomaterials were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). According to TGA, the obtained Fe3O4/SiO2-NH2-DTPA nanoadsorbents contained up to 0.401 mmol/g of DTPA groups. In the concentration range Ceq = 0–50 mmol/L, maximum adsorption capacities towards Cu (II) and Cd (II) ions were 1.1 mmol/g and 1.7 mmol/g, respectively. Langmuir adsorption model fits experimental data in concentration range Ceq = 0–10 mmol/L. The adsorption mechanisms have been evaluated for both of cations. Crosslinking of 5 wt % of immobilized urease with glutaraldehyde prevented the loss of the enzyme in repeated use of the adsorbent and improved the stability of the enzymatic function leading to unchanged activity in at least 18 cycles. Crosslinking of 10 wt % urease on the surface of the particles allowed a decrease in urea concentration in 20 mmol/L model solutions to 2 mmol/L in up to 10 consequent decomposition cycles. Due to the presence of DTPA groups, Cu2+ ions in concentration 1 µmol/L did not significantly affect the urease activity. Obtained magnetic Fe3O4/SiO2-NH2-DTPA-Urease nanocomposite sorbents revealed a high potential for urease decomposition, even in presence of heavy metal ions. Full article
(This article belongs to the Special Issue Sol-Gel Preparation of Nanomaterials)
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Open AccessArticle Ionic Liquid Confined in Mesoporous Polymer Membrane with Improved Stability for CO2/N2 Separation
Nanomaterials 2017, 7(10), 299; doi:10.3390/nano7100299
Received: 11 August 2017 / Revised: 20 September 2017 / Accepted: 25 September 2017 / Published: 29 September 2017
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Abstract
Supported ionic liquid membranes (SILMs) have a promising prospect of application in flue gas separation, owing to its high permeability and selectivity of CO2. However, existing SILMs have the disadvantage of poor stability due to the loss of ionic liquid from
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Supported ionic liquid membranes (SILMs) have a promising prospect of application in flue gas separation, owing to its high permeability and selectivity of CO2. However, existing SILMs have the disadvantage of poor stability due to the loss of ionic liquid from the large pores of the macroporous support. In this study, a novel SILM with high stability was developed by confining ionic liquid in a mesoporous polymer membrane. First, a mesoporous polymer membrane derived from a soluble, low-molecular-weight phenolic resin precursor was deposited on a porous Al2O3 support, and then 1-ethyl-3-methylimidazolium tetrafluoroborate ([emim][BF4]) was immobilized inside mesopores of phenolic resin, forming the SILM under vacuum. Effects of trans-membrane pressure difference on the SILM separation performance were investigated by measuring the permeances of CO2 and N2. The SILM exhibits a high ideal CO2/N2 selectivity of 40, and an actual selectivity of approximately 25 in a mixed gas (50% CO2 and 50% N2) at a trans-membrane pressure difference of 2.5 bar. Compared to [emim][BF4] supported by polyethersulfone membrane with a pore size of around 0.45 μm, the [emim][BF4] confined in a mesoporous polymer membrane exhibits an improved stability, and its separation performance remained stable for 40 h under a trans-membrane pressure difference of 1.5 bar in a mixed gas before the measurement was intentionally stopped. Full article
(This article belongs to the Special Issue Hybrid Nanomaterials for Future Technologies)
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Open AccessArticle Pro-Inflammatory versus Immunomodulatory Effects of Silver Nanoparticles in the Lung: The Critical Role of Dose, Size and Surface Modification
Nanomaterials 2017, 7(10), 300; doi:10.3390/nano7100300
Received: 15 August 2017 / Revised: 20 September 2017 / Accepted: 21 September 2017 / Published: 29 September 2017
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Abstract
The growing use of silver nanoparticles (Ag-NPs) in consumer products raises concerns about their toxicological potential. The purpose of the study was to investigate the size- and coating-dependent pulmonary toxicity of Ag-NPs in vitro and in vivo, using an ovalbumin (OVA)-mouse allergy model.
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The growing use of silver nanoparticles (Ag-NPs) in consumer products raises concerns about their toxicological potential. The purpose of the study was to investigate the size- and coating-dependent pulmonary toxicity of Ag-NPs in vitro and in vivo, using an ovalbumin (OVA)-mouse allergy model. Supernatants from (5.6–45 µg/mL) Ag50-PVP, Ag200-PVP or Ag50-citrate-treated NR8383 alveolar macrophages were tested for lactate dehydrogenase and glucuronidase activity, tumor necrosis factor (TNF)-α release and reactive oxygen species (ROS) production. For the in vivo study, NPs were intratracheally instilled in non-sensitized (NS) and OVA-sensitized (S) mice (1–50 µg/mouse) prior to OVA-challenge and bronchoalveolar lavage fluid (BALF) inflammatory infiltrate was evaluated five days after challenge. In vitro results showed a dose-dependent cytotoxicity of Ag-NPs, which was highest for Ag50-polyvinilpyrrolidone (PVP), followed by Ag50-citrate, and lowest for Ag200-PVP. In vivo 10–50 µg Ag50-PVP triggered a dose-dependent pulmonary inflammatory milieu in NS and S mice, which was significantly higher in S mice and was dampened upon instillation of Ag200-PVP. Surprisingly, instillation of 1 µg Ag50-PVP significantly reduced OVA-induced inflammatory infiltrate in S mice and had no adverse effect in NS mice. Ag50-citrate showed similar beneficial effects at low concentrations and attenuated pro-inflammatory effects at high concentrations. The lung microbiome was altered by NPs instillation dependent on coating and/or mouse batch, showing the most pronounced effects upon instillation of 50 µg Ag50-citrate, which caused an increased abundance of operational taxonomic units assigned to Actinobacteria, Bacteroidetes, Firmicutes and Proteobacteria. However, no correlation with the biphasic effect of low and high Ag-NPs dose was found. Altogether, both in vitro and in vivo data on the pulmonary effects of Ag-NPs suggest the critical role of the size, dose and surface functionalization of Ag-NPs, especially in susceptible allergic individuals. From the perspective of occupational health, care should be taken by the production of Ag-NPs-containing consumer products. Full article
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Open AccessArticle Graphene Quantum Dots Electrochemistry and Sensitive Electrocatalytic Glucose Sensor Development
Nanomaterials 2017, 7(10), 301; doi:10.3390/nano7100301
Received: 4 September 2017 / Revised: 26 September 2017 / Accepted: 26 September 2017 / Published: 29 September 2017
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Abstract
Graphene quantum dots (GQDs), derived from functionalized graphene precursors are graphene sheets a few nanometers in the lateral dimension having a several-layer thickness. They are zero-dimensional materials with quantum confinement and edge site effects. Intense research interest in GQDs is attributed to their
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Graphene quantum dots (GQDs), derived from functionalized graphene precursors are graphene sheets a few nanometers in the lateral dimension having a several-layer thickness. They are zero-dimensional materials with quantum confinement and edge site effects. Intense research interest in GQDs is attributed to their unique physicochemical phenomena arising from the sp2-bonded carbon nanocore surrounded with edged plane functional moieties. In this work, GQDs are synthesized by both solvothermal and hydrothermal techniques, with the optimal size of 5 nm determined using high-resolution transmission electron microscopy, with additional UV-Vis absorption and fluorescence spectroscopy, revealing electronic band signatures in the blue-violet region. Their potential in fundamental (direct electron transfer) and applied (enzyme-based glucose biosensor) electrochemistry has been practically realized. Glucose oxidase (GOx) was immobilized on glassy carbon (GC) electrodes modified with GQDs and functionalized graphene (graphene oxide and reduced form). The cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy are used for characterizing the direct electron transfer kinetics and electrocatalytical biosensing. The well-defined quasi-reversible redox peaks were observed under various electrochemical environment and conditions (pH, concentration, scan rate) to determine the diffusion coefficient (D) and first-order electron transfer rate (kET). The cyclic voltammetry curves showed homogeneous ion transport behavior for GQD and other graphene-based samples with D ranging between 8.45 × 10−9 m2 s−1 and 3 × 10−8 m2 s−1 following the order of GO < rGO < GQD < GQD (with FcMeOH as redox probe) < GOx/rGO < GOx/GO < HRP/GQDs < GOx/GQDs. The developed GOx-GQDs biosensor responds efficiently and linearly to the presence of glucose over concentrations ranging between 10 μM and 3 mM with a limit of detection of 1.35 μM and sensitivity of 0.00769 μA μM−1·cm−2 as compared with rGO (0.025 μA μM−1 cm−2, 4.16 μM) and GO (0.064 μA μM−1 cm−2, 4.82 μM) nanosheets. The relatively high performance and stability of GQDs is attributed to a sufficiently large surface-to-volume ratio, excellent biocompatibility, abundant hydrophilic edges, and a partially hydrophobic plane that favors GOx adsorption on the electrode surface and versatile architectures to ensure rapid charge transfer and electron/ion conduction (<10 ms). We also carried out similar studies with other enzymatic protein biomolecules on electrode surfaces prepared from GQD precursors for electrochemical comparison, thus opening up potential sensing applications in medicine as well as bio-nanotechnology. Full article
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Open AccessArticle N-Doped Graphene with Low Intrinsic Defect Densities via a Solid Source Doping Technique
Nanomaterials 2017, 7(10), 302; doi:10.3390/nano7100302
Received: 18 August 2017 / Revised: 19 September 2017 / Accepted: 25 September 2017 / Published: 30 September 2017
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Abstract
N-doped graphene with low intrinsic defect densities was obtained by combining a solid source doping technique and chemical vapor deposition (CVD). The solid source for N-doping was embedded into the copper substrate by NH3 plasma immersion. During the treatment, NH3 plasma
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N-doped graphene with low intrinsic defect densities was obtained by combining a solid source doping technique and chemical vapor deposition (CVD). The solid source for N-doping was embedded into the copper substrate by NH3 plasma immersion. During the treatment, NH3 plasma radicals not only flattened the Cu substrate such that the root-mean-square roughness value gradually decreased from 51.9 nm to 15.5 nm but also enhanced the nitrogen content in the Cu substrate. The smooth surface of copper enables good control of graphene growth and the decoupling of height fluctuations and ripple effects, which compensate for the Coulomb scattering by nitrogen incorporation. On the other hand, the nitrogen atoms on the pre-treated Cu surface enable nitrogen incorporation with low defect densities, causing less damage to the graphene structure during the process. Most incorporated nitrogen atoms are found in the pyrrolic configuration, with the nitrogen fraction ranging from 1.64% to 3.05%, while the samples exhibit low defect densities, as revealed by Raman spectroscopy. In the top-gated graphene transistor measurement, N-doped graphene exhibits n-type behavior, and the obtained carrier mobilities are greater than 1100 cm2·V−1·s−1. In this study, an efficient and minimally damaging n-doping approach was proposed for graphene nanoelectronic applications. Full article
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Open AccessArticle Magnetically Separable MoS2/Fe3O4/nZVI Nanocomposites for the Treatment of Wastewater Containing Cr(VI) and 4-Chlorophenol
Nanomaterials 2017, 7(10), 303; doi:10.3390/nano7100303
Received: 12 August 2017 / Revised: 21 September 2017 / Accepted: 25 September 2017 / Published: 30 September 2017
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Abstract
With a large specific surface area, high reactivity, and excellent adsorption properties, nano zerovalent iron (nZVI) can degrade a wide variety of contaminants in wastewater. However, aggregation, oxidation, and separation issues greatly impede its wide application. In this study, MoS2/Fe3
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With a large specific surface area, high reactivity, and excellent adsorption properties, nano zerovalent iron (nZVI) can degrade a wide variety of contaminants in wastewater. However, aggregation, oxidation, and separation issues greatly impede its wide application. In this study, MoS2/Fe3O4/nZVI nanocomposites were successfully synthesized by a facile step-by-step approach to overcome these problems. MoS2 nanosheets (MNs) acted as an efficient support for nZVI and enriched the organic pollutants nearby, leading to an enhanced removal efficiency. Fe3O4 nanoparticles (NPs) could not only suppress the agglomeration and restacking of MNs, but also facilitate easy separation and recovery of the nanocomposites. The synergistic effect between MNs and Fe3O4 NPs effectively enhanced the reactivity and efficiency of nZVI. In the system, Cr(VI) was reduced to Cr(III) by nZVI in the nanocomposites, and Fe2+ produced in the process was combined with H2O2 to further remove 4-Chlorophenol (4-CP) through a Fenton reaction. Furthermore, the nanocomposites could be easily separated from wastewater by a magnet and be reused for at least five consecutive runs, revealing good reusability. The results demonstrate that the novel nanocomposites are highly efficient and promising for the simultaneous removal of Cr(VI) and 4-CP in wastewater. Full article
(This article belongs to the Special Issue Preparation and Application of Hybrid Nanomaterials)
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Open AccessArticle Creating Active Device Materials for Nanoelectronics Using Block Copolymer Lithography
Nanomaterials 2017, 7(10), 304; doi:10.3390/nano7100304
Received: 12 September 2017 / Revised: 22 September 2017 / Accepted: 25 September 2017 / Published: 30 September 2017
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Abstract
The prolonged and aggressive nature of scaling to augment the performance of silicon integrated circuits (ICs) and the technical challenges and costs associated with this has led to the study of alternative materials that can use processing schemes analogous to semiconductor manufacturing. We
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The prolonged and aggressive nature of scaling to augment the performance of silicon integrated circuits (ICs) and the technical challenges and costs associated with this has led to the study of alternative materials that can use processing schemes analogous to semiconductor manufacturing. We examine the status of recent efforts to develop active device elements using nontraditional lithography in this article, with a specific focus on block copolymer (BCP) feature patterning. An elegant route is demonstrated using directed self-assembly (DSA) of BCPs for the fabrication of aligned tungsten trioxide (WO3) nanowires towards nanoelectronic device application. The strategy described avoids conventional lithography practices such as optical patterning as well as repeated etching and deposition protocols and opens up a new approach for device development. Nanoimprint lithography (NIL) silsesquioxane (SSQ)-based trenches were utilized in order to align a cylinder forming poly(styrene)-block-poly(4-vinylpyridine) (PS-b-P4VP) BCP soft template. We outline WO3 nanowire fabrication using a spin-on process and the symmetric current-voltage characteristics of the resulting Ti/Au (5 nm/45 nm) contacted WO3 nanowires. The results highlight the simplicity of a solution-based approach that allows creating active device elements and controlling the chemistry of specific self-assembling building blocks. The process enables one to dictate nanoscale chemistry with an unprecedented level of sophistication, forging the way for next-generation nanoelectronic devices. We lastly outline views and future research studies towards improving the current platform to achieve the desired device performance. Full article
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Open AccessArticle Surface Functionalization of Iron Oxide Nanoparticles with Gallic Acid as Potential Antioxidant and Antimicrobial Agents
Nanomaterials 2017, 7(10), 306; doi:10.3390/nano7100306
Received: 5 August 2017 / Revised: 28 August 2017 / Accepted: 30 August 2017 / Published: 5 October 2017
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Abstract
In this research, we report the size-controlled synthesis and surface-functionalization of magnetite with the natural antioxidant gallic acid (GA) as a ligand, using in situ and post-synthesis methods. GA functionalization provided narrow size distribution, with an average particle size of 5 and 8
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In this research, we report the size-controlled synthesis and surface-functionalization of magnetite with the natural antioxidant gallic acid (GA) as a ligand, using in situ and post-synthesis methods. GA functionalization provided narrow size distribution, with an average particle size of 5 and 8 nm for in situ synthesis of gallic acid functionalized magnetite IONP@GA1 and IONP@GA2, respectively, which are ultra-small particles as compared to unfunctionalized magnetite (IONP) and post functionalized magnetite IONP@GA3 with average size of 10 and 11 nm respectively. All the IONPs@GA samples were found hydrophilic with stable aggregation state. Prior to commencement of experimental lab work, PASS software was used to predict the biological activities of GA and it is found that experimental antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and antimicrobial studies using well diffusion method are in good agreement with the simulated results. Furthermore, the half maximal inhibitory concentration (IC50) values of DPPH antioxidant assay revealed a 2–4 fold decrease as compared to unfunctionalized IONP. In addition to antioxidant activity, all the three IONP@GA proved outstanding antimicrobial activity while testing on different bacterial and fungal strains. The results collectively indicate the successful fabrication of novel antioxidant, antimicrobial IONP@GA composite, which are magnetically separable, efficient, and low cost, with potential applications in polymers, cosmetics, and biomedical and food industries. Full article
(This article belongs to the Special Issue Magnetic Nanoparticles in Biological Applications)
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Open AccessArticle Flexible Piezoelectric Generators by Using the Bending Motion Method of Direct-Grown-PZT Nanoparticles on Carbon Nanotubes
Nanomaterials 2017, 7(10), 308; doi:10.3390/nano7100308
Received: 16 August 2017 / Revised: 18 September 2017 / Accepted: 2 October 2017 / Published: 7 October 2017
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Abstract
Recently, composite-type nanogenerators (NGs) formed from piezoelectric nanostructures and multi-walled carbon nanotubes (CNTs), have become one of the excellent candidates for future energy harvesting because of their ability to apply the excellent electrical and mechanical properties of CNTs. However, the synthesis of NG
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Recently, composite-type nanogenerators (NGs) formed from piezoelectric nanostructures and multi-walled carbon nanotubes (CNTs), have become one of the excellent candidates for future energy harvesting because of their ability to apply the excellent electrical and mechanical properties of CNTs. However, the synthesis of NG devices with a high proportion of piezoelectric materials and a low polymer content, such as of polydimethylsiloxane (PDMS), continues to be problematic. In this work, high-piezoelectric-material-content flexible films produced from Pb(Zr,Ti)O3 (PZT)-atomically-interconnected CNTs and polytetrafluoroethylene (PTFE) are presented. Various physical and chemical characterization techniques are employed to examine the morphology and structure of the materials. The direct growth of the piezoelectric material on the CNTs, by stirring the PZT and CNT mixed solution, results in various positive effects, such as a high-quality dispersion in the polymer matrix and addition of flexoelectricity to piezoelectricity, resulting in the enhancement of the output voltage by an external mechanical force. The NGs repeatedly generate an output voltage of 0.15 V. These results present a significant step toward the application of NGs using piezoelectric nanocomposite materials. Full article
(This article belongs to the Special Issue Nanogenerators and Self-Powered Nanosystems)
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Open AccessArticle Effect of Ge Nanocrystals on 1.54 μm Photoluminescence Enhancement in Er2O3:ZnO and Ge Co-Sputtered Films
Nanomaterials 2017, 7(10), 311; doi:10.3390/nano7100311
Received: 3 September 2017 / Revised: 30 September 2017 / Accepted: 9 October 2017 / Published: 11 October 2017
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Abstract
Photoluminescence (PL) of Er and Ge co-doped ZnO films synthesized by radio frequency magnetron co-sputtering was investigated. X-ray diffraction (XRD) patterns showed that the annealing process at 400–800 °C led to the formation of nanocrystal (nc) Ge. Samples containing nc-Ge showed a strong
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Photoluminescence (PL) of Er and Ge co-doped ZnO films synthesized by radio frequency magnetron co-sputtering was investigated. X-ray diffraction (XRD) patterns showed that the annealing process at 400–800 °C led to the formation of nanocrystal (nc) Ge. Samples containing nc-Ge showed a strong visible PL with a peak at 582–593 nm, which was consistent with the calculated energy of the exciton of the ~5 nm-sized nc-Ge, according to the quantum confinement effect. The formation of nc-Ge could greatly enhance the 1.54 μm emission, and it is considered that the 1.54 μm PL enhancement may come from a joint effect of both the energy transfer from nc-Ge to Er3+ and the local environment change of Er3+. Full article
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Open AccessArticle Impact of Temperature and UV Irradiation on Dynamics of NO2 Sensors Based on ZnO Nanostructures
Nanomaterials 2017, 7(10), 312; doi:10.3390/nano7100312
Received: 4 September 2017 / Revised: 2 October 2017 / Accepted: 5 October 2017 / Published: 11 October 2017
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Abstract
The main object of this study is the improvement of the dynamics of NO2 sensors based on ZnO nanostructures. Investigations presented in this paper showed that the combination of temperature and ultraviolet (UV) activation of the sensors can significantly decrease the sensor
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The main object of this study is the improvement of the dynamics of NO2 sensors based on ZnO nanostructures. Investigations presented in this paper showed that the combination of temperature and ultraviolet (UV) activation of the sensors can significantly decrease the sensor response and regeneration times. In comparison with the single activation method (elevated temperature or UV), these times for 1 ppm of NO2 decreased from about 10 min (or more) to less than 40 s. In addition, at the optimal conditions (200 °C and UV), sensors were very stable, were fully scalable (in the range on NO2 concentration of 1–20 ppm) and baseline drift was significantly reduced. Furthermore, in this paper, extensive studies of the influence of temperature and carrier gas (nitrogen and air) on NO2 sensing properties of the ZnO nanostructures were conducted. The NO2 sensing mechanisms of the sensors operating at elevated temperatures and under UV irradiation were also discussed. Our study showed that sensor responses to NO2 and response/regeneration times are comparable from sensor to sensor in air and nitrogen conditions, which suggests that the proposed simple technology connected with well-chosen operation conditions is repeatable. The estimated limit of detection of the sensors is within the level of ≈800 ppb in nitrogen and ≈700 ppb in air. Full article
(This article belongs to the Special Issue Oxide Nanomaterials for Chemical Sensors)
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Open AccessArticle Three-Dimensional Porous Nitrogen-Doped NiO Nanostructures as Highly Sensitive NO2 Sensors
Nanomaterials 2017, 7(10), 313; doi:10.3390/nano7100313
Received: 11 September 2017 / Revised: 2 October 2017 / Accepted: 8 October 2017 / Published: 11 October 2017
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Abstract
Nickel oxide has been widely used in chemical sensing applications, because it has an excellent p-type semiconducting property with high chemical stability. Here, we present a novel technique of fabricating three-dimensional porous nitrogen-doped nickel oxide nanosheets as a highly sensitive NO2 sensor.
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Nickel oxide has been widely used in chemical sensing applications, because it has an excellent p-type semiconducting property with high chemical stability. Here, we present a novel technique of fabricating three-dimensional porous nitrogen-doped nickel oxide nanosheets as a highly sensitive NO2 sensor. The elaborate nanostructure was prepared by a simple and effective hydrothermal synthesis method. Subsequently, nitrogen doping was achieved by thermal treatment with ammonia gas. When the p-type dopant, i.e., nitrogen atoms, was introduced in the three-dimensional nanostructures, the nickel-oxide-nanosheet-based sensor showed considerable NO2 sensing ability with two-fold higher responsivity and sensitivity compared to non-doped nickel-oxide-based sensors. Full article
(This article belongs to the Special Issue Nanomaterials for Sensing Applications)
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Open AccessArticle Evaluation of the Ability of Nanostructured PEI-Coated Iron Oxide Nanoparticles to Incorporate Cisplatin during Synthesis
Nanomaterials 2017, 7(10), 314; doi:10.3390/nano7100314
Received: 25 August 2017 / Revised: 26 September 2017 / Accepted: 5 October 2017 / Published: 12 October 2017
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Abstract
Nanoparticles (NPs) have a high potential for biological applications as they can be used as carriers for the controlled release of bioactive factors. Here we focused on poly(ethylenimine) (PEI)-coated iron oxide hybrid NPs obtained by hydrothermal synthesis in high pressure conditions and evaluated
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Nanoparticles (NPs) have a high potential for biological applications as they can be used as carriers for the controlled release of bioactive factors. Here we focused on poly(ethylenimine) (PEI)-coated iron oxide hybrid NPs obtained by hydrothermal synthesis in high pressure conditions and evaluated their behavior in culture medium in the presence or absence of cells, as well as their ability to incorporate antitumor drug cisplatin. Our results showed that the hydrothermal conditions used for Fe-PEI NPs synthesis allowed the incorporation of cisplatin, which even increased its anti-tumor effects. Furthermore, the commonly occurring phenomenon of NPs aggregation in culture medium was exploited for further entrapment of other active molecules, such as the fluorescent dye DiI and valinomycin. The molecules bound to NPs during synthesis or during aggregation process were delivered inside various cells after in vitro and in vivo direct contact between cells and NPs and their biological activity was preserved, thus supporting the therapeutic value of Fe-PEI NPs as drug delivery tools. Full article
(This article belongs to the Special Issue Nanomaterials for Imaging, Diagnosis or Therapy)
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Open AccessArticle TiO2 Nanowire Networks Prepared by Titanium Corrosion and Their Application to Bendable Dye-Sensitized Solar Cells
Nanomaterials 2017, 7(10), 315; doi:10.3390/nano7100315
Received: 10 August 2017 / Revised: 20 September 2017 / Accepted: 25 September 2017 / Published: 12 October 2017
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Abstract
TiO2 nanowire networks were prepared, using the corrosion of Ti foils in alkaline (potassium hydroxide, KOH) solution at different temperatures, and then a further ion-exchange process. The prepared nanostructures were characterized by field emission scanning electron microscopy, Raman spectroscopy, and X-ray photoelectron
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TiO2 nanowire networks were prepared, using the corrosion of Ti foils in alkaline (potassium hydroxide, KOH) solution at different temperatures, and then a further ion-exchange process. The prepared nanostructures were characterized by field emission scanning electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. The wet corroded foils were utilized as the photoanodes of bendable dye-sensitized solar cells (DSSCs), which exhibited a power conversion efficiency of 1.11% under back illumination. Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures)
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Open AccessArticle Periodic TiO2 Nanostructures with Improved Aspect and Line/Space Ratio Realized by Colloidal Photolithography Technique
Nanomaterials 2017, 7(10), 316; doi:10.3390/nano7100316
Received: 11 September 2017 / Revised: 29 September 2017 / Accepted: 5 October 2017 / Published: 12 October 2017
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Abstract
This paper presents substantial improvements of the colloidal photolithography technique (also called microsphere lithography) with the goal of better controlling the geometry of the fabricated nano-scale structures—in this case, hexagonally arranged nanopillars—printed in a layer of directly photopatternable sol-gel TiO2. Firstly,
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This paper presents substantial improvements of the colloidal photolithography technique (also called microsphere lithography) with the goal of better controlling the geometry of the fabricated nano-scale structures—in this case, hexagonally arranged nanopillars—printed in a layer of directly photopatternable sol-gel TiO2. Firstly, to increase the achievable structure height the photosensitive layer underneath the microspheres is deposited on a reflective layer instead of the usual transparent substrate. Secondly, an increased width of the pillars is achieved by tilting the incident wave and using multiple exposures or substrate rotation, additionally allowing to better control the shape of the pillar’s cross section. The theoretical analysis is carried out by rigorous modelling of the photonics nanojet underneath the microspheres and by optimizing the experimental conditions. Aspect ratios (structure height/lateral structure size) greater than 2 are predicted and demonstrated experimentally for structure dimensions in the sub micrometer range, as well as line/space ratios (lateral pillar size/distance between pillars) greater than 1. These nanostructures could lead for example to materials exhibiting efficient light trapping in the visible and near-infrared range, as well as improved hydrophobic or photocatalytic properties for numerous applications in environmental and photovoltaic systems. Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures)
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Open AccessArticle Hierarchical AuNPs-Loaded Fe3O4/Polymers Nanocomposites Constructed by Electrospinning with Enhanced and Magnetically Recyclable Catalytic Capacities
Nanomaterials 2017, 7(10), 317; doi:10.3390/nano7100317
Received: 1 October 2017 / Revised: 10 October 2017 / Accepted: 10 October 2017 / Published: 12 October 2017
Cited by 2 | PDF Full-text (14272 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Gold nanoparticles (AuNPs) have attracted widespread attention for their excellent catalytic activity, as well as their unusual physical and chemical properties. The main challenges come from the agglomeration and time-consuming separation of gold nanoparticles, which have greatly baffled the development and application in
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Gold nanoparticles (AuNPs) have attracted widespread attention for their excellent catalytic activity, as well as their unusual physical and chemical properties. The main challenges come from the agglomeration and time-consuming separation of gold nanoparticles, which have greatly baffled the development and application in liquid phase selective reduction. To solve these problems, we propose the preparation of polyvinyl alcohol(PVA)/poly(acrylic acid)(PAA)/Fe3O4 nanocomposites with loaded AuNPs. The obtained PVA/PAA/Fe3O4 composite membrane by electrospinning demonstrated high structural stability, a large specific surface area, and more active sites, which is conducive to promoting good dispersion of AuNPs on membrane surfaces. The subsequently prepared PVA/PAA/Fe3O4@AuNPs nanocomposites exhibited satisfactory nanostructures, robust thermal stability, and a favorable magnetic response for recycling. In addition, the PVA/PAA/Fe3O4@AuNPs nanocomposites showed a remarkable catalytic capacity in the catalytic reduction of p-nitrophenol and 2-nitroaniline solutions. In addition, the regeneration studies toward p-nitrophenol for different consecutive cycles demonstrate that the as-prepared PVA/PAA/Fe3O4@AuNPs nanocomposites have outstanding stability and recycling in catalytic reduction. Full article
(This article belongs to the Special Issue Polymer Nanocomposites)
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Open AccessArticle Upcycling Waste Lard Oil into Vertical Graphene Sheets by Inductively Coupled Plasma Assisted Chemical Vapor Deposition
Nanomaterials 2017, 7(10), 318; doi:10.3390/nano7100318
Received: 7 August 2017 / Revised: 2 September 2017 / Accepted: 7 September 2017 / Published: 12 October 2017
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Abstract
Vertical graphene (VG) sheets were single-step synthesized via inductively coupled plasma (ICP)-enhanced chemical vapor deposition (PECVD) using waste lard oil as a sustainable and economical carbon source. Interweaved few-layer VG sheets, H2, and other hydrocarbon gases were obtained after the decomposition
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Vertical graphene (VG) sheets were single-step synthesized via inductively coupled plasma (ICP)-enhanced chemical vapor deposition (PECVD) using waste lard oil as a sustainable and economical carbon source. Interweaved few-layer VG sheets, H2, and other hydrocarbon gases were obtained after the decomposition of waste lard oil. The influence of parameters such as temperature, gas proportion, ICP power was investigated to tune the nanostructures of obtained VG, which indicated that a proper temperature and H2 concentration was indispensable for the synthesis of VG sheets. Rich defects of VG were formed with a high I D / I G ratio (1.29), consistent with the dense edges structure observed in electron microscopy. Additionally, the morphologies, crystalline degree, and wettability of nanostructure carbon induced by PECVD and ICP separately were comparatively analyzed. The present work demonstrated the potential of our PECVD recipe to synthesize VG from abundant natural waste oil, which paved the way to upgrade the low-value hydrocarbons into advanced carbon material. Full article
(This article belongs to the Special Issue Nanomaterials for Renewable and Sustainable Energy)
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Open AccessArticle Feedback System Control Optimized Electrospinning for Fabrication of an Excellent Superhydrophobic Surface
Nanomaterials 2017, 7(10), 319; doi:10.3390/nano7100319
Received: 20 August 2017 / Revised: 30 September 2017 / Accepted: 8 October 2017 / Published: 13 October 2017
PDF Full-text (5142 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Superhydrophobic surface, as a promising micro/nano material, has tremendous applications in biological and artificial investigations. The electrohydrodynamics (EHD) technique is a versatile and effective method for fabricating micro- to nanoscale fibers and particles from a variety of materials. A combination of critical parameters,
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Superhydrophobic surface, as a promising micro/nano material, has tremendous applications in biological and artificial investigations. The electrohydrodynamics (EHD) technique is a versatile and effective method for fabricating micro- to nanoscale fibers and particles from a variety of materials. A combination of critical parameters, such as mass fraction, ratio of N, N-Dimethylformamide (DMF) to Tetrahydrofuran (THF), inner diameter of needle, feed rate, receiving distance, applied voltage as well as temperature, during electrospinning process, to determine the morphology of the electrospun membranes, which in turn determines the superhydrophobic property of the membrane. In this study, we applied a recently developed feedback system control (FSC) scheme for rapid identification of the optimal combination of these controllable parameters to fabricate superhydrophobic surface by one-step electrospinning method without any further modification. Within five rounds of experiments by testing totally forty-six data points, FSC scheme successfully identified an optimal parameter combination that generated electrospun membranes with a static water contact angle of 160 degrees or larger. Scanning electron microscope (SEM) imaging indicates that the FSC optimized surface attains unique morphology. The optimized setup introduced here therefore serves as a one-step, straightforward, and economic approach to fabricate superhydrophobic surface with electrospinning approach. Full article
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Open AccessArticle Effect of Nanoparticles on the Morphology, Thermal, and Electrical Properties of Low-Density Polyethylene after Thermal Aging
Nanomaterials 2017, 7(10), 320; doi:10.3390/nano7100320
Received: 17 September 2017 / Revised: 27 September 2017 / Accepted: 28 September 2017 / Published: 12 October 2017
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Abstract
This paper investigates the morphology, thermal, and electrical properties of LDPE (low-density polyethylene)-based nanocomposites after thermal aging. The FTIR (Fourier transform infrared spectroscopy) spectra results show that thermo-oxidative reactions occur in neat LDPE and LDPE/SiO2 nanocomposites when the aging time is 35
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This paper investigates the morphology, thermal, and electrical properties of LDPE (low-density polyethylene)-based nanocomposites after thermal aging. The FTIR (Fourier transform infrared spectroscopy) spectra results show that thermo-oxidative reactions occur in neat LDPE and LDPE/SiO2 nanocomposites when the aging time is 35 days and in LDPE/MgO nanocomposites when the aging time is 77 days. Specifically, LDPE/MgO nanocomposites delay the appearance of thermo-oxidative reactions, showing anti-thermal aging ability. Furthermore, nanocomposites present lower onset degradation temperature than neat LDPE, showing better thermal stabilization. With regard to the electrical properties, nanocomposites maintain the ability to suppress space charge accumulation after thermal aging. Additionally, in comparison with SiO2 nanocomposites and neat LDPE, the permittivity of LDPE/MgO nanocomposites changes slightly after thermal aging. It is concluded that LDPE/MgO nanocomposites have better insulation properties than neat LDPE after thermal aging, which may be caused by the interface introduced by the nanoparticles. Full article
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Open AccessFeature PaperArticle Nanometric MIL-125-NH2 Metal–Organic Framework as a Potential Nerve Agent Antidote Carrier
Nanomaterials 2017, 7(10), 321; doi:10.3390/nano7100321
Received: 21 July 2017 / Revised: 29 September 2017 / Accepted: 6 October 2017 / Published: 12 October 2017
PDF Full-text (2409 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The three-dimensional (3D) microporous titanium aminoterephthalate MIL-125-NH2 (MIL: Material of Institut Lavoisier) was successfully isolated as monodispersed nanoparticles, which are compatible with intravenous administration, by using a simple, safe and low-cost synthetic approach (100 °C/32 h under atmospheric pressure) so that for
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The three-dimensional (3D) microporous titanium aminoterephthalate MIL-125-NH2 (MIL: Material of Institut Lavoisier) was successfully isolated as monodispersed nanoparticles, which are compatible with intravenous administration, by using a simple, safe and low-cost synthetic approach (100 °C/32 h under atmospheric pressure) so that for the first time it could be considered for encapsulation and the release of drugs. The nerve agent antidote 2-[(hydroxyimino)methyl]-1-methyl-pyridinium chloride (2-PAM or pralidoxime) was effectively encapsulated into the pores of MIL-125-NH2 as a result of the interactions between 2-PAM and the pore walls being mediated by π-stacking and hydrogen bonds, as deduced from infrared spectroscopy and Monte Carlo simulation studies. Finally, colloidal solutions of MIL-125-NH2 nanoparticles exhibited remarkable stability in different organic media, aqueous solutions at different pH and under relevant physiological conditions over time (24 h). 2-PAM was rapidly released from the pores of MIL-125-NH2 in vitro. Full article
(This article belongs to the Special Issue Nanoparticles in Metal-Organic Frameworks)
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Open AccessArticle Porcine Dental Epithelial Cells Differentiated in a Cell Sheet Constructed by Magnetic Nanotechnology
Nanomaterials 2017, 7(10), 322; doi:10.3390/nano7100322
Received: 14 September 2017 / Revised: 7 October 2017 / Accepted: 9 October 2017 / Published: 13 October 2017
PDF Full-text (7921 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Magnetic nanoparticles (MNPs) are widely used in medical examinations, treatments, and basic research, including magnetic resonance imaging, drug delivery systems, and tissue engineering. In this study, MNPs with magnetic force were applied to tissue engineering for dental enamel regeneration. The internalization of MNPs
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Magnetic nanoparticles (MNPs) are widely used in medical examinations, treatments, and basic research, including magnetic resonance imaging, drug delivery systems, and tissue engineering. In this study, MNPs with magnetic force were applied to tissue engineering for dental enamel regeneration. The internalization of MNPs into the odontogenic cells was observed by transmission electron microscopy. A combined cell sheet consisting of dental epithelial cells (DECs) and dental mesenchymal cells (DMCs) (CC sheet) was constructed using magnetic force-based tissue engineering technology. The result of the iron staining indicated that MNPs were distributed ubiquitously over the CC sheet. mRNA expression of enamel differentiation and basement membrane markers was examined in the CC sheet. Immunostaining showed Collagen IV expression at the border region between DEC and DMC layers in the CC sheet. These results revealed that epithelial–mesenchymal interactions between DEC and DMC layers were caused by bringing DECs close to DMCs mechanically by magnetic force. Our study suggests that the microenvironment in the CC sheet might be similar to that during the developmental stage of a tooth bud. In conclusion, a CC sheet employing MNPs could be developed as a novel and unique graft for artificially regenerating dental enamel. Full article
(This article belongs to the Special Issue Tissue Engineering and Regenerative Nanomedicine)
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Open AccessArticle Bioactive Coating with Two-Layer Hierarchy of Relief Obtained by Sol-Gel Method with Shock Drying and Osteoblast Response of Its Structure
Nanomaterials 2017, 7(10), 323; doi:10.3390/nano7100323
Received: 8 September 2017 / Revised: 9 October 2017 / Accepted: 9 October 2017 / Published: 13 October 2017
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Abstract
In this work, we analyze the efficiency of the modification of the implant surface. This modification was reached by the formation of a two-level relief hierarchy by means of a sol-gel approach that included dip coating with subsequent shock drying. Using this method,
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In this work, we analyze the efficiency of the modification of the implant surface. This modification was reached by the formation of a two-level relief hierarchy by means of a sol-gel approach that included dip coating with subsequent shock drying. Using this method, we fabricated a nanoporous layer with micron-sized defects on the nanotitanium surface. The present work continues an earlier study by our group, wherein the effect of osteoblast-like cell adhesion acceleration was found. In the present paper, we give the results of more detailed evaluation of coating efficiency. Specifically, cytological analysis was performed that included the study of the marker levels of osteoblast-like cell differentiation. We found a significant increase in the activity of alkaline phosphatase at the initial incubation stage. This is very important for implantation, since such an effect assists the decrease in the induction time of implant engraftment. Moreover, osteopontin expression remains high for long expositions. This indicates a prolonged osteogenic effect in the coating. The results suggest the acceleration of the pre-implant area mineralization and, correspondingly, the potential use of the developed coatings for bone implantation. Full article
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Open AccessArticle Molecular Mechanics of the Moisture Effect on Epoxy/Carbon Nanotube Nanocomposites
Nanomaterials 2017, 7(10), 324; doi:10.3390/nano7100324
Received: 14 August 2017 / Revised: 8 October 2017 / Accepted: 9 October 2017 / Published: 13 October 2017
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Abstract
The strong structural integrity of polymer nanocomposite is influenced in the moist environment; but the fundamental mechanism is unclear, including the basis for the interactions between the absorbed water molecules and the structure, which prevents us from predicting the durability of its applications
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The strong structural integrity of polymer nanocomposite is influenced in the moist environment; but the fundamental mechanism is unclear, including the basis for the interactions between the absorbed water molecules and the structure, which prevents us from predicting the durability of its applications across multiple scales. In this research, a molecular dynamics model of the epoxy/single-walled carbon nanotube (SWCNT) nanocomposite is constructed to explore the mechanism of the moisture effect, and an analysis of the molecular interactions is provided by focusing on the hydrogen bond (H-bond) network inside the nanocomposite structure. The simulations show that at low moisture concentration, the water molecules affect the molecular interactions by favorably forming the water-nanocomposite H-bonds and the small cluster, while at high concentration the water molecules predominantly form the water-water H-bonds and the large cluster. The water molecules in the epoxy matrix and the epoxy-SWCNT interface disrupt the molecular interactions and deteriorate the mechanical properties. Through identifying the link between the water molecules and the nanocomposite structure and properties, it is shown that the free volume in the nanocomposite is crucial for its structural integrity, which facilitates the moisture accumulation and the distinct material deteriorations. This study provides insights into the moisture-affected structure and properties of the nanocomposite from the nanoscale perspective, which contributes to the understanding of the nanocomposite long-term performance under the moisture effect. Full article
(This article belongs to the Special Issue Polymer Nanocomposites)
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Open AccessArticle Transformation of CuO Nanoparticles in the Aquatic Environment: Influence of pH, Electrolytes and Natural Organic Matter
Nanomaterials 2017, 7(10), 326; doi:10.3390/nano7100326
Received: 17 September 2017 / Revised: 11 October 2017 / Accepted: 11 October 2017 / Published: 14 October 2017
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Abstract
Many studies have shown the effect of solution chemistry on the environmental behavior of metal-based nanoparticles (NPs), except CuO NPs. Here, we investigated the agglomeration, sedimentation, dissolution, and speciation of CuO NPs by varying pH, ionic strength, ionic valence, and natural organic matter
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Many studies have shown the effect of solution chemistry on the environmental behavior of metal-based nanoparticles (NPs), except CuO NPs. Here, we investigated the agglomeration, sedimentation, dissolution, and speciation of CuO NPs by varying pH, ionic strength, ionic valence, and natural organic matter (NOM). The results showed that as the pH moved away from 6, the size of CuO agglomerates decreased, along with the enhanced NP suspension stabilization, due to the increase of electrostatic repulsive force. Increasing ionic strength and valence intensified the agglomeration and sedimentation of CuO NPs because of the compression of electrical double layers. The presence of humic acid and citric acid enhanced the dispersion and stabilization of CuO NP suspension, but l-cysteine showed a different impact. Decreasing pH, increasing ionic strength and all NOM improved the dissolution of CuO NPs, but the divalent electrolyte (CaCl2) inhibited the Cu2+ release from CuO NPs compared to the monovalent electrolyte (NaCl). In addition, X-ray absorption near edge structure (XANES) analysis demonstrated that the presence of l-cysteine transformed more than 30% of CuO NPs to Cu(I)-cysteine by coordinating with thiol group. This study can give us an in-depth understanding on the environmental behavior and fate of CuO NPs in the aquatic environment. Full article
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Open AccessArticle Regulation of the Electroanalytical Performance of Ultrathin Titanium Dioxide Nanosheets toward Lead Ions by Non-Metal Doping
Nanomaterials 2017, 7(10), 327; doi:10.3390/nano7100327
Received: 13 September 2017 / Revised: 10 October 2017 / Accepted: 10 October 2017 / Published: 14 October 2017
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Abstract
Three non-metallic elements, sulfur, fluorine, and iodine, were used to dope the ultrathin two-dimensional TiO2 nanosheets, which would regulate their electroanalytical properties toward heavy metal ions. Among these doped materials, fluorine-doped TiO2 nanosheets shows the highest electrochemical sensitivity and a superior
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Three non-metallic elements, sulfur, fluorine, and iodine, were used to dope the ultrathin two-dimensional TiO2 nanosheets, which would regulate their electroanalytical properties toward heavy metal ions. Among these doped materials, fluorine-doped TiO2 nanosheets shows the highest electrochemical sensitivity and a superior detection limit toward Pb(II) when the doping concentration is 10%. When compared with the bare TiO2 nanosheets, the sensitivity increased by 102%, and the detection limit decreased by 36.4%. Through combining further electrochemical experiments and density-functional theory calculations, the enhanced electrochemical performance stemming from element doping was then investigated in detail. The theoretical calculation demonstrated that fluorine doping could greatly increase the adsorption energy of Pb(II) on the TiO2 nanosheets and enhance their loading capacity. Both cyclic voltammetric and electrical impedance spectroscopy analysis indicated the enhanced electron transfer rate on the electrode modified by fluorine-doped TiO2 nanosheets. Further measurement on the desorption performance showed the better stripping response of Pb(II) on the electrode with TiO2 nanosheets after fluorine doping, which suggests that fluorine doping is beneficial for Pb(II) diffuse onto the electrode surface for the reduction and stripping reaction. Therefore, the element doping of two-dimensional TiO2 nanosheets provides a facile method to extend the electronic materials toward detection of heavy metal ions in the environment. Full article
(This article belongs to the Special Issue Nanomaterials for Sensing Applications)
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Open AccessArticle Evaluation of MC3T3 Cells Proliferation and Drug Release Study from Sodium Hyaluronate-1,4-butanediol Diglycidyl Ether Patterned Gel
Nanomaterials 2017, 7(10), 328; doi:10.3390/nano7100328
Received: 18 September 2017 / Revised: 20 September 2017 / Accepted: 5 October 2017 / Published: 14 October 2017
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Abstract
A pattern gel has been fabricated using sodium hyaluronate (HA) and 1,4-butanediol diglycidyl ether (BDDGE) through the micro-molding technique. The cellular behavior of osteoblast cells (MC3T3) in the presence and absence of dimethyloxalylglycine (DMOG) and sodium borate (NaB) in the pattern gel (HA-BDDGE)
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A pattern gel has been fabricated using sodium hyaluronate (HA) and 1,4-butanediol diglycidyl ether (BDDGE) through the micro-molding technique. The cellular behavior of osteoblast cells (MC3T3) in the presence and absence of dimethyloxalylglycine (DMOG) and sodium borate (NaB) in the pattern gel (HA-BDDGE) has been evaluated for its potential application in bone regeneration. The Fourier transform infrared spectroscopy (FTIR), 13C-nuclear magnetic resonance spectroscopy (13C NMR), and thermogravimetric analysis (TGA) results implied the crosslinking reaction between HA and BDDGE. The scanning electron microscopy (SEM) analysis confirmed the formation of pattern on the surface of HA-BDDGE. The gel property of the crosslinked HA-BDDGE has been investigated by swelling study in distilled water at 37 °C. The HA-BDDGE gel releases DMOG in a controlled way for up to seven days in water at 37 °C. The synthesized gel is biocompatible and the bolus drug delivery results indicated that the DMOG containing patterned gel demonstrates a better cell migration ability on the surface than NaB. For local delivery, the pattern gel with 300 µM NaB or 300 µM DMOG induced cell clusters formation, and the gel with 150 µM NaB/DMOG showed high cell proliferation capability only. The vital role of NaB for bone regeneration has been endorsed from the formation of cell clusters in presence of NaB in the media. The in vitro results indicated that the pattern gel showed angiogenic and osteogenic responses with good ALP activity and enhanced HIF-1α, and Runx2 levels in the presence of DMOG and NaB in MC3T3 cells. Hence, the HA-BDDGE gel could be used in bone regeneration application. Full article
(This article belongs to the Special Issue Frontiers in Toxicity and Functionalization of Nanomaterials)
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Open AccessArticle The Effect of TiO2 Doped Photocatalytic Nano-Additives on the Hydration and Microstructure of Portland and High Alumina Cements
Nanomaterials 2017, 7(10), 329; doi:10.3390/nano7100329
Received: 20 September 2017 / Revised: 11 October 2017 / Accepted: 11 October 2017 / Published: 14 October 2017
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Abstract
Mortars with two different binders (Portland cement (PC) and high alumina cement (HAC)) were modified upon the bulk incorporation of nano-structured photocatalytic additives (bare TiO2, and TiO2 doped with either iron (Fe-TiO2) or vanadium (V-TiO2)). Plastic
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Mortars with two different binders (Portland cement (PC) and high alumina cement (HAC)) were modified upon the bulk incorporation of nano-structured photocatalytic additives (bare TiO2, and TiO2 doped with either iron (Fe-TiO2) or vanadium (V-TiO2)). Plastic and hardened state properties of these mortars were assessed in order to study the influence of these nano-additives. Water demand was increased, slightly by bare TiO2 and Fe-TiO2, and strongly by V-TiO2, in agreement with the reduction of the particle size and the tendency to agglomerate. Isothermal calorimetry showed that hydration of the cementitious matrices was accelerated due to additional nucleation sites offered by the nano-additives. TiO2 and doped TiO2 did not show pozzolanic reactivity in the binding systems. Changes in the pore size distribution, mainly the filler effect of the nano-additives, accounted for the increase in compressive strengths measured for HAC mortars. A complex microstructure was seen in calcium aluminate cement mortars, strongly dependent on the curing conditions. Fe-TiO2 was found to be homogeneously distributed whereas the tendency of V-TiO2 to agglomerate was evidenced by elemental distribution maps. Water absorption capacity was not affected by the nano-additive incorporation in HAC mortars, which is a favourable feature for the application of these mortars. Full article
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Open AccessFeature PaperArticle Modeling of Interactions between the Zebrafish Hatching Enzyme ZHE1 and A Series of Metal Oxide Nanoparticles: Nano-QSAR and Causal Analysis of Inactivation Mechanisms
Nanomaterials 2017, 7(10), 330; doi:10.3390/nano7100330
Received: 19 September 2017 / Revised: 12 October 2017 / Accepted: 12 October 2017 / Published: 16 October 2017
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Abstract
The quantitative relationships between the activity of zebrafish ZHE1 enzyme and a series of experimental and physicochemical features of 24 metal oxide nanoparticles were revealed. Vital characteristics of the nanoparticles’ structure were reflected using both experimental and theoretical descriptors. The developed quantitative structure–activity
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The quantitative relationships between the activity of zebrafish ZHE1 enzyme and a series of experimental and physicochemical features of 24 metal oxide nanoparticles were revealed. Vital characteristics of the nanoparticles’ structure were reflected using both experimental and theoretical descriptors. The developed quantitative structure–activity relationship model for nanoparticles (nano-QSAR) was capable of predicting the enzyme inactivation based on four descriptors: the hydrodynamic radius, mass density, the Wigner–Seitz radius, and the covalent index. The nano-QSAR model was calculated using the non-linear regression tree M5P algorithm. The developed model is characterized by high robustness R2bagging = 0.90 and external predictivity Q2EXT = 0.93. This model is in agreement with modern theories of aquatic toxicity. Dissolution and size-dependent characteristics are among the key driving forces for enzyme inactivation. It was proven that ZnO, CuO, Cr2O3, and NiO nanoparticles demonstrated strong inhibitory effects because of their solubility. The proposed approach could be used as a non-experimental alternative to animal testing. Additionally, methods of causal discovery were applied to shed light on the mechanisms and modes of action. Full article
(This article belongs to the Special Issue Experimental Nanosciences, Computational Chemistry, and Data Analysis)
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Open AccessArticle A Sub-Microanalysis Approach in Chemical Characterisation of Gold Nanorods Formed by a Novel Polymer-Immobilised Gold Seeds Base
Nanomaterials 2017, 7(10), 331; doi:10.3390/nano7100331
Received: 29 August 2017 / Revised: 19 September 2017 / Accepted: 10 October 2017 / Published: 16 October 2017
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Abstract
Gold nanorods (GNRs) have been fabricated by a novel polymer-immobilised seed mediated method using ultraviolet (UV) photoreduced gold-polymethylmethacrylate (Au–PMMA) nanocomposites as a seed platform and characterised at sub-micron scale regime with synchrotron-based techniques; near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and X-ray fluorescence
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Gold nanorods (GNRs) have been fabricated by a novel polymer-immobilised seed mediated method using ultraviolet (UV) photoreduced gold-polymethylmethacrylate (Au–PMMA) nanocomposites as a seed platform and characterised at sub-micron scale regime with synchrotron-based techniques; near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and X-ray fluorescence (XRF) mapping. In this report, it is shown that investigating polymer nanocomposites using combination of XRF mapping and NEXAFS spectromicroscopy can help to see the growth phenomenon from different perspective than conventional characterisation techniques. XRF maps are used to explore distribution of the constituent elements and showing how polymer matrix making stripe patterns along with regions where GNRs are formed. NEXAFS carbon (C) K-edge spectra have been taken at three different stages of synthesis: (1) on Au–PMMA nanocomposites before UV irradiation, (2) after gold nanoparticles formation, and (3) after GNRs formation. It reveals how polymer matrix has been degraded during GNRs formation and avoiding chemically or physically damage to polymer matrix is crucial to control the formation of GNRs. Full article
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Open AccessFeature PaperArticle PMA-Induced THP-1 Macrophage Differentiation is Not Impaired by Citrate-Coated Platinum Nanoparticles
Nanomaterials 2017, 7(10), 332; doi:10.3390/nano7100332
Received: 25 September 2017 / Revised: 12 October 2017 / Accepted: 13 October 2017 / Published: 17 October 2017
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Abstract
The innate immune system consists of several complex cellular and molecular mechanisms. During inflammatory responses, blood-circulating monocytes are driven to the sites of inflammation, where they differentiate into tissue macrophages. The research of novel nanomaterials applied to biomedical sciences is often limited by
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The innate immune system consists of several complex cellular and molecular mechanisms. During inflammatory responses, blood-circulating monocytes are driven to the sites of inflammation, where they differentiate into tissue macrophages. The research of novel nanomaterials applied to biomedical sciences is often limited by their toxicity or dangerous interactions with the immune cell functions. Platinum nanoparticles (PtNPs) have shown efficient antioxidant properties within several cells, but information on their potential harmful role in the monocyte-to-macrophage differentiation process is still unknown. Here, we studied the morphology and the release of cytokines in PMA-differentiated THP-1 pre-treated with 5 nm PtNPs. Although NP endocytosis was evident, we did not find differences in the cellular structure or in the release of inflammatory cytokines and chemokines compared to cells differentiated in PtNP-free medium. However, the administration of PtNPs to previously differentiated THP-1 induced massive phagocytosis of the PtNPs and a slight metabolism decrease at higher doses. Further investigation using undifferentiated and differentiated neutrophil-like HL60 confirmed the harmlessness of PtNPs with non-adherent innate immune cells. Our results demonstrate that citrate-coated PtNPs are not toxic with these immune cell lines, and do not affect the PMA-stimulated THP-1 macrophage differentiation process in vitro. Full article
(This article belongs to the Special Issue Nanoparticles in Immunology)
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Open AccessArticle AuPd Bimetallic Nanocrystals Embedded in Magnetic Halloysite Nanotubes: Facile Synthesis and Catalytic Reduction of Nitroaromatic Compounds
Nanomaterials 2017, 7(10), 333; doi:10.3390/nano7100333
Received: 28 September 2017 / Revised: 13 October 2017 / Accepted: 13 October 2017 / Published: 17 October 2017
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Abstract
In this research, a facile and effective approach was developed for the preparation of well-designed AuPd alloyed catalysts supported on magnetic halloysite nanotubes (HNTs@Fe3O4@AuPd). The microstructure and the magnetic properties of HNTs@Fe3O4@AuPd were confirmed by
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In this research, a facile and effective approach was developed for the preparation of well-designed AuPd alloyed catalysts supported on magnetic halloysite nanotubes (HNTs@Fe3O4@AuPd). The microstructure and the magnetic properties of HNTs@Fe3O4@AuPd were confirmed by transmission electron microscopy (TEM), high resolution TEM (HRTEM), energy-dispersive X-ray spectroscopy (EDS), and vibrating sample magnetometry (VSM) analyses. The catalysts, fabricated by a cheap, environmentally friendly, and simple surfactant-free formation process, exhibited high activities during the reduction of 4-nitrophenol and various other nitroaromatic compounds. Moreover, the catalytic activities of the HNTs@Fe3O4@AuPd nanocatalysts were tunable via adjusting the atomic ratio of AuPd during the synthesis. As compared with the monometallic nanocatalysts (HNTs@Fe3O4@Au and HNTs@Fe3O4@Pd), the bimetallic alloyed HNTs@Fe3O4@AuPd nanocatalysts exhibited excellent catalytic activities toward the reduction of 4-nitrophenol (4-NP) to 4-aminophenol. Furthermore, the as-obtained HNTs@Fe3O4@AuPd can be recycled several times, while retaining its functionality due to the stability and magnetic separation property. Full article
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Open AccessArticle Microstructuring of Mesoporous Titania Films Loaded with Silver Salts to Enhance the Photocatalytic Degradation of Methyl Blue under Visible Light
Nanomaterials 2017, 7(10), 334; doi:10.3390/nano7100334
Received: 22 September 2017 / Revised: 29 September 2017 / Accepted: 5 October 2017 / Published: 17 October 2017
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Abstract
The microstructuring of the distribution of silver nanoparticles (NPs) in mesoporous titania films loaded with silver salts, using two-beam interference lithography leading to 1 Dimension (1D) grating, induces variations in the photocatalytic efficiency. The influence of the structuration was tested on the degradation
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The microstructuring of the distribution of silver nanoparticles (NPs) in mesoporous titania films loaded with silver salts, using two-beam interference lithography leading to 1 Dimension (1D) grating, induces variations in the photocatalytic efficiency. The influence of the structuration was tested on the degradation of methyl blue (MB) under ultraviolet (UV) and visible illumination, giving rise to a significant improvement of the photocatalytic efficiency. The periodic distribution of the NPs was characterized by transmission electron microscopy (TEM), high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) and scanning electron microscopy (SEM). Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures)
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Open AccessArticle Precise Placement of Metallic Nanowires on a Substrate by Localized Electric Fields and Inter-Nanowire Electrostatic Interaction
Nanomaterials 2017, 7(10), 335; doi:10.3390/nano7100335
Received: 25 September 2017 / Revised: 11 October 2017 / Accepted: 16 October 2017 / Published: 19 October 2017
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Abstract
Placing nanowires at the predetermined locations on a substrate represents one of the significant hurdles to be tackled for realization of heterogeneous nanowire systems. Here, we demonstrate spatially-controlled assembly of a single nanowire at the photolithographically recessed region at the electrode gap with
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Placing nanowires at the predetermined locations on a substrate represents one of the significant hurdles to be tackled for realization of heterogeneous nanowire systems. Here, we demonstrate spatially-controlled assembly of a single nanowire at the photolithographically recessed region at the electrode gap with high integration yield (~90%). Two popular routes, such as protruding electrode tips and recessed wells, for spatially-controlled nanowire alignment, are compared to investigate long-range dielectrophoretic nanowire attraction and short-range nanowire-nanowire electrostatic interaction for determining the final alignment of attracted nanowires. Furthermore, the post-assembly process has been developed and tested to make a robust electrical contact to the assembled nanowires, which removes any misaligned ones and connects the nanowires to the underlying electrodes of circuit. Full article
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Open AccessArticle Enhanced UV-Visible Light Photocatalytic Activity by Constructing Appropriate Heterostructures between Mesopore TiO2 Nanospheres and Sn3O4 Nanoparticles
Nanomaterials 2017, 7(10), 336; doi:10.3390/nano7100336
Received: 25 September 2017 / Revised: 12 October 2017 / Accepted: 13 October 2017 / Published: 19 October 2017
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Abstract
Novel TiO2/Sn3O4 heterostructure photocatalysts were ingeniously synthesized via a scalable two-step method. The impressive photocatalytic abilities of the TiO2/Sn3O4 sphere nanocomposites were validated by the degradation test of methyl orange and •OH trapping
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Novel TiO2/Sn3O4 heterostructure photocatalysts were ingeniously synthesized via a scalable two-step method. The impressive photocatalytic abilities of the TiO2/Sn3O4 sphere nanocomposites were validated by the degradation test of methyl orange and •OH trapping photoluminescence experiments under ultraviolet (UV) and visible light irradiation, respectively. Especially under the visible light, the TiO2/Sn3O4 nanocomposites demonstrated a superb photocatalytic activity, with 81.2% of methyl orange (MO) decomposed at 30 min after irradiation, which greatly exceeded that of the P25 (13.4%), TiO2 (0.5%) and pure Sn3O4 (59.1%) nanostructures. This enhanced photocatalytic performance could be attributed to the mesopore induced by the monodispersed TiO2 cores that supply sufficient surface areas and accessibility to reactant molecules. This exquisite hetero-architecture facilitates extended UV-visible absorption and efficient photoexcited charge carrier separation. Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures)
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Open AccessArticle Raman Enhancement and Photo-Bleaching of Organic Dyes in the Presence of Chemical Vapor Deposition-Grown Graphene
Nanomaterials 2017, 7(10), 337; doi:10.3390/nano7100337
Received: 18 September 2017 / Revised: 10 October 2017 / Accepted: 16 October 2017 / Published: 19 October 2017
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Abstract
Fluorescent organic dyes photobleach under intense light. Graphene has been shown to improve the photo-stability of organic dyes. In this paper, we investigated the Raman spectroscopy and photo-bleaching kinetics of dyes in the absence/presence of chemical vapor deposition (CVD)-grown graphene. We show that
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Fluorescent organic dyes photobleach under intense light. Graphene has been shown to improve the photo-stability of organic dyes. In this paper, we investigated the Raman spectroscopy and photo-bleaching kinetics of dyes in the absence/presence of chemical vapor deposition (CVD)-grown graphene. We show that graphene enhances the Raman signal of a wide range of dyes. The photo-bleaching of the dyes was reduced when the dyes were in contact with graphene. In contrast, monolayer hexagonal boron nitride (h-BN) was much less effective in reducing the photo-bleaching rate of the dyes. We attribute the suppression of photo-bleaching to the energy or electron transfer from dye to graphene. The results highlight the potential of CVD graphene as a substrate for protecting and enhancing Raman response of organic dyes. Full article
(This article belongs to the Special Issue Synthesis, Structure and Applications of 2D Nanomaterials)
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Open AccessArticle Study of the Photodynamic Activity of N-Doped TiO2 Nanoparticles Conjugated with Aluminum Phthalocyanine
Nanomaterials 2017, 7(10), 338; doi:10.3390/nano7100338
Received: 29 September 2017 / Revised: 14 October 2017 / Accepted: 17 October 2017 / Published: 20 October 2017
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Abstract
TiO2 nanoparticles modified with phthalocyanines (Pc) have been proven to be a potential photosensitizer in the application of photodynamic therapy (PDT). However, the generation of reactive oxygen species (ROS) by TiO2 nanoparticles modified with Pc has not been demonstrated clearly. In
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TiO2 nanoparticles modified with phthalocyanines (Pc) have been proven to be a potential photosensitizer in the application of photodynamic therapy (PDT). However, the generation of reactive oxygen species (ROS) by TiO2 nanoparticles modified with Pc has not been demonstrated clearly. In this study, nitrogen-doped TiO2 conjugated with Pc (N-TiO2-Pc) were studied by means of monitoring the generation of ROS. The absorbance and photokilling effect on HeLa cells upon visible light of different regions were also studied and compared with non-doped TiO2-Pc and Pc. Both N-TiO2-Pc and TiO2-Pc can be activated by visible light and exhibited much higher photokilling effect on HeLa cells than Pc. In addition, nitrogen-doping can greatly enhance the formation of 1O2 and •O2, while it suppresses the generation of OH•. This resulted in significant photodynamic activity. Therefore, N-TiO2-Pc can be an excellent candidate for a photosensitizer in PDT with wide-spectrum visible irradiation. Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures)
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Open AccessArticle Few-Flakes Reduced Graphene Oxide Sensors for Organic Vapors with a High Signal-to-Noise Ratio
Nanomaterials 2017, 7(10), 339; doi:10.3390/nano7100339
Received: 23 September 2017 / Revised: 14 October 2017 / Accepted: 18 October 2017 / Published: 21 October 2017
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Abstract
This paper reports our findings on how to prepare a graphene oxide-based gas sensor for sensing fast pulses of volatile organic compounds with a better signal-to-noise ratio. We use rapid acetone pulses of varying concentrations to test the sensors. First, we compare the
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This paper reports our findings on how to prepare a graphene oxide-based gas sensor for sensing fast pulses of volatile organic compounds with a better signal-to-noise ratio. We use rapid acetone pulses of varying concentrations to test the sensors. First, we compare the effect of graphene oxide deposition method (dielectrophoresis versus solvent evaporation) on the sensor’s response. We find that dielectrophoresis yields films with uniform coverage and better sensor response. Second, we examine the effect of chemical reduction. Contrary to prior reports, we find that graphene oxide reduction leads to a reduction in sensor response and current noise, thus keeping the signal-to-noise ratio the same. We found that if we sonicated the sensor in acetone, we created a sensor with a few flakes of reduced graphene oxide. Such sensors provided a higher signal-to-noise ratio that could be correlated to the vapor concentration of acetone with better repeatability. Modeling shows that the sensor’s response is due to one-site Langmuir adsorption or an overall single exponent process. Further, the desorption of acetone as deduced from the sensor recovery signal follows a single exponent process. Thus, we show a simple way to improve the signal-to-noise ratio in reduced graphene oxide sensors. Full article
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Open AccessArticle Enhancing Photovoltaic Performance Using Broadband Luminescent Down-Shifting by Combining Multiple Species of Eu-Doped Silicate Phosphors
Nanomaterials 2017, 7(10), 340; doi:10.3390/nano7100340
Received: 23 September 2017 / Revised: 16 October 2017 / Accepted: 18 October 2017 / Published: 21 October 2017
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Abstract
This paper demonstrates the application of a broadband luminescent downshifting (LDS) layer with multiple species of europium (Eu)-doped silicate phosphors using spin-on film technique to enhance the photovoltaic efficiency of crystalline silicon solar cells. The surface morphology of the deposited layer was examined
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This paper demonstrates the application of a broadband luminescent downshifting (LDS) layer with multiple species of europium (Eu)-doped silicate phosphors using spin-on film technique to enhance the photovoltaic efficiency of crystalline silicon solar cells. The surface morphology of the deposited layer was examined using a scanning electron microscope (SEM). The chemical composition of the Eu-doped silicate phosphors was analyzed using energy-dispersive X-ray spectroscopy (EDS). The fluorescence emission of the Eu-doped silicate phosphors was characterized using photoluminescence (PL) measurements at room temperature. We also compared the optical reflectance and external quantum efficiency (EQE) response of cells with combinations of various Eu-doped phosphors species. The cell coated with two species of Eu-doped phosphors achieved a conversion efficiency enhancement (∆η) of 19.39%, far exceeding the ∆η = 15.08% of the cell with one species of Eu-doped phosphors and the ∆η = 8.51% of the reference cell with the same silicate layer without Eu-doped phosphors. Full article
(This article belongs to the Special Issue Nanomaterials for Renewable and Sustainable Energy)
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Open AccessFeature PaperArticle Flotation Assembly of Large-Area Ultrathin MWCNT Nanofilms for Construction of Bioelectrodes
Nanomaterials 2017, 7(10), 342; doi:10.3390/nano7100342
Received: 1 October 2017 / Revised: 18 October 2017 / Accepted: 19 October 2017 / Published: 21 October 2017
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Abstract
We report a simple, versatile, and rapid method for the fabrication of optically-transparent large-area carbon nanotube (CNT) films via flotation assembly. After solvent-induced assembly, floating films were transferred to a flat supporting substrate to form conductive and transparent CNT film electrodes. The resulting
[...] Read more.
We report a simple, versatile, and rapid method for the fabrication of optically-transparent large-area carbon nanotube (CNT) films via flotation assembly. After solvent-induced assembly, floating films were transferred to a flat supporting substrate to form conductive and transparent CNT film electrodes. The resulting electrodes, with uniform 40 ± 20 nm multi-walled CNT (MWCNT) layers, were characterized by electrochemical and microscopy methods. The flotation method does not require specialized thin-film instrumentation and avoids the need for surfactants and pre-oxidized CNTs which can hamper electrochemical performance. A proof-of-concept nanostructured bioelectrode demonstrating high sensitivity for glucose was developed with an electropolymerized poly(pyrene-adamantane) layer for host–guest immobilization of active β-cyclodextrin tagged GOx enzymes. The polymer provides pyrene groups for cross-linking to CNTs and pendant adamantane groups for binding the β-cyclodextrin groups of the tagged enzyme. This demonstration offers a new approach for the preparation of stable and transparent CNT film electrodes with attractive electrochemical properties towards future photobio- and bio-electrochemical fuel cells, electrochemical sensors, and electroanalysis. Full article
(This article belongs to the Special Issue Nanostructured Biofuel Cells)
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Open AccessArticle Ti-Based Biomedical Material Modified with TiOx/TiNx Duplex Bioactivity Film via Micro-Arc Oxidation and Nitrogen Ion Implantation
Nanomaterials 2017, 7(10), 343; doi:10.3390/nano7100343
Received: 29 September 2017 / Revised: 16 October 2017 / Accepted: 18 October 2017 / Published: 23 October 2017
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Abstract
Titanium (Ti) and Ti-based alloy are widely used in the biomedical field owing to their excellent mechanical compatibility and biocompatibility. However, the bioinert bioactivity and biotribological properties of titanium limit its clinical application in implants. In order to improve the biocompatibility of titanium,
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Titanium (Ti) and Ti-based alloy are widely used in the biomedical field owing to their excellent mechanical compatibility and biocompatibility. However, the bioinert bioactivity and biotribological properties of titanium limit its clinical application in implants. In order to improve the biocompatibility of titanium, we modified its surface with TiOx/TiNx duplex composite films using a new method via micro-arc oxidation (MAO) and nitrogen ion implantation (NII) treatment. The structural characterization results revealed that the modified film was constructed by nanoarrays composed of TiOx/TiNx composite nanostitches with a size of 20~40 nm. Meanwhile, comparing this with pure Ti, the friction property, wear resistance, and bioactivity were significantly improved based on biotribological results and in vitro bioactivity tests. Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures)
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Open AccessArticle Evaluation of the Effects of Nanoparticle Mixtures on Brassica Seed Germination and Bacterial Bioluminescence Activity Based on the Theory of Probability
Nanomaterials 2017, 7(10), 344; doi:10.3390/nano7100344
Received: 2 September 2017 / Revised: 11 October 2017 / Accepted: 17 October 2017 / Published: 23 October 2017
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Abstract
Effects of binary mixtures of six metal oxide nanoparticles (NPs; 54 combinations) on the activities of seed germination and bacterial bioluminescence were investigated using the theory of probability. The observed toxicities of various NPs combinations were compared with the theoretically expected toxicities, calculated
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Effects of binary mixtures of six metal oxide nanoparticles (NPs; 54 combinations) on the activities of seed germination and bacterial bioluminescence were investigated using the theory of probability. The observed toxicities of various NPs combinations were compared with the theoretically expected toxicities, calculated based on individual NPs toxicities. Different sensitivities were observed depending on the concentrations and the types of NPs. The synergistic mode (67%; observed toxicity greater than expected toxicity) was predominantly observed in the bioluminescence test, whereas both synergistic (47%) and additive (50%) modes were prevalent in the activity of seed germination. With regard to overall analysis, a slightly high percentage (56%) of the synergistic mode of action was (30 out of 54 binary mixture combinations; p < 0.0392) observed. These results suggest that the exposure of an NPs mixture in the environment may lead to a similar or higher toxicity level than the sum of its constituent NPs would suggest. In addition, one organism for assessment did not always show same results as those from a different assessment. Therefore, combining results of different organisms exposed to a wide range of concentrations of binary mixture will more properly predict and evaluate the expected ecotoxicity of pollutants on environments. Full article
(This article belongs to the Special Issue Oxide Nanomaterials for Chemical Sensors)
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Open AccessArticle Enhanced Efficiency in Dye-Sensitized Solar Cells by Electron Transport and Light Scattering on Freestanding TiO2 Nanotube Arrays
Nanomaterials 2017, 7(10), 345; doi:10.3390/nano7100345
Received: 14 September 2017 / Revised: 18 October 2017 / Accepted: 19 October 2017 / Published: 24 October 2017
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Abstract
Dye-sensitized solar cells (DSSCs) were fabricated with closed- or open-ended freestanding TiO2 nanotube arrays as photoelectrodes that were decorated with carbon materials and large TiO2 nanoparticles (NPs) to enhance energy conversion efficiency. The energy conversion efficiency of DSSCs based on open-ended
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Dye-sensitized solar cells (DSSCs) were fabricated with closed- or open-ended freestanding TiO2 nanotube arrays as photoelectrodes that were decorated with carbon materials and large TiO2 nanoparticles (NPs) to enhance energy conversion efficiency. The energy conversion efficiency of DSSCs based on open-ended freestanding TiO2 nanotube arrays increased from 4.47% to 5.39%, compared to the DSSCs based on closed-ended freestanding TiO2 nanotube arrays. In DSSCs based on the open-ended freestanding TiO2 nanotube arrays, the energy conversion efficiency with carbon materials increased from 5.39% to 6.19% due to better electron transport, and that with a scattering layer from 5.39% to 6.24% due to more light harvesting compared to the DSSCs without carbon materials or scattering layer. Moreover, the energy conversion efficiency of DSSCs based on the open-ended freestanding TiO2 nanotube arrays with both carbon materials and scattering layer increased from 5.39% to 6.98%, which is an enhancement of 29.50%. In DSSCs based on the TiO2 nanotube arrays, the carbon materials can improve electron transport by π-π conjugation, and the large TiO2 NPs can enhance the capacity to light-harvest by scattering. Full article
(This article belongs to the Special Issue New Developments in Nanomaterials for Energy Storage and Conversions)
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Review

Jump to: Research, Other

Open AccessFeature PaperReview Lyotropic Liquid Crystal Phases from Anisotropic Nanomaterials
Nanomaterials 2017, 7(10), 305; doi:10.3390/nano7100305
Received: 11 August 2017 / Revised: 14 September 2017 / Accepted: 14 September 2017 / Published: 1 October 2017
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Abstract
Liquid crystals are an integral part of a mature display technology, also establishing themselves in other applications, such as spatial light modulators, telecommunication technology, photonics, or sensors, just to name a few of the non-display applications. In recent years, there has been an
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Liquid crystals are an integral part of a mature display technology, also establishing themselves in other applications, such as spatial light modulators, telecommunication technology, photonics, or sensors, just to name a few of the non-display applications. In recent years, there has been an increasing trend to add various nanomaterials to liquid crystals, which is motivated by several aspects of materials development. (i) addition of nanomaterials can change and thus tune the properties of the liquid crystal; (ii) novel functionalities can be added to the liquid crystal; and (iii) the self-organization of the liquid crystalline state can be exploited to template ordered structures or to transfer order onto dispersed nanomaterials. Much of the research effort has been concentrated on thermotropic systems, which change order as a function of temperature. Here we review the other side of the medal, the formation and properties of ordered, anisotropic fluid phases, liquid crystals, by addition of shape-anisotropic nanomaterials to isotropic liquids. Several classes of materials will be discussed, inorganic and mineral liquid crystals, viruses, nanotubes and nanorods, as well as graphene oxide. Full article
(This article belongs to the Special Issue Nanomaterials in Liquid Crystals)
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Open AccessReview Potential Toxicity and Underlying Mechanisms Associated with Pulmonary Exposure to Iron Oxide Nanoparticles: Conflicting Literature and Unclear Risk
Nanomaterials 2017, 7(10), 307; doi:10.3390/nano7100307
Received: 7 September 2017 / Revised: 26 September 2017 / Accepted: 28 September 2017 / Published: 6 October 2017
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Abstract
Abstract: Fine/micron-sized iron oxide particulates are incidentally released from a number of industrial processes, including iron ore mining, steel processing, welding, and pyrite production. Some research suggests that occupational exposure to these particulates is linked to an increased risk of adverse respiratory outcomes,
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Abstract: Fine/micron-sized iron oxide particulates are incidentally released from a number of industrial processes, including iron ore mining, steel processing, welding, and pyrite production. Some research suggests that occupational exposure to these particulates is linked to an increased risk of adverse respiratory outcomes, whereas other studies suggest that iron oxide is biologically benign. Iron oxide nanoparticles (IONPs), which are less than 100 nm in diameter, have recently surged in use as components of novel drug delivery systems, unique imaging protocols, as environmental catalysts, and for incorporation into thermoplastics. However, the adverse outcomes associated with occupational exposure to IONPs remain relatively unknown. Relevant in vivo studies suggest that pulmonary exposure to IONPs may induce inflammation, pulmonary fibrosis, genotoxicity, and extra-pulmonary effects. This correlates well with in vitro studies that utilize relevant dose, cell type(s), and meaningful end points. A majority of these adverse outcomes are attributed to increased oxidative stress, most likely caused by particle internalization, dissolution, release of free iron ions, and disruption of iron homeostasis. However, because the overall toxicity profile of IONPs is not well understood, it is difficult to set safe exposure limit recommendations that would be adequate for the protection of at-risk workers. This review article will focus on known risks following IONPs exposure supported by human, animal, and cell culture-based studies, the potential challenges intrinsic to IONPs toxicity assessment, and how these may contribute to the poorly characterized IONPs toxicity profile. Full article
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Open AccessReview Wet-Chemical Preparation of TiO2-Based Composites with Different Morphologies and Photocatalytic Properties
Nanomaterials 2017, 7(10), 310; doi:10.3390/nano7100310
Received: 7 September 2017 / Revised: 30 September 2017 / Accepted: 2 October 2017 / Published: 9 October 2017
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Abstract
TiO2-based composites have been paid significant attention in the photocatalysis field. The size, crystallinity and nanomorphology of TiO2 materials have an important effect on the photocatalytic efficiency. The synthesis and photocatalytic activity of TiO2-based materials have been widely
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TiO2-based composites have been paid significant attention in the photocatalysis field. The size, crystallinity and nanomorphology of TiO2 materials have an important effect on the photocatalytic efficiency. The synthesis and photocatalytic activity of TiO2-based materials have been widely investigated in past decades. Based on our group’s research works on TiO2 materials, this review introduces several methods for the fabrication of TiO2, rare-earth-doped TiO2 and noble-metal-decorated TiO2 particles with different morphologies. We focused on the preparation and the formation mechanism of TiO2-based materials with unique structures including spheres, hollow spheres, porous spheres, hollow porous spheres and urchin-like spheres. The photocatalytical activity of urchin-like TiO2, noble metal nanoparticle-decorated 3D (three-dimensional) urchin-like TiO2 and bimetallic core/shell nanoparticle-decorated urchin-like hierarchical TiO2 are briefly discussed. Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures)
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Open AccessReview Recent Progresses and Development of Advanced Atomic Layer Deposition towards High-Performance Li-Ion Batteries
Nanomaterials 2017, 7(10), 325; doi:10.3390/nano7100325
Received: 31 August 2017 / Revised: 23 September 2017 / Accepted: 26 September 2017 / Published: 14 October 2017
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Abstract
Electrode materials and electrolytes play a vital role in device-level performance of rechargeable Li-ion batteries (LIBs). However, electrode structure/component degeneration and electrode-electrolyte sur-/interface evolution are identified as the most crucial obstacles in practical applications. Thanks to its congenital advantages, atomic layer deposition (ALD)
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Electrode materials and electrolytes play a vital role in device-level performance of rechargeable Li-ion batteries (LIBs). However, electrode structure/component degeneration and electrode-electrolyte sur-/interface evolution are identified as the most crucial obstacles in practical applications. Thanks to its congenital advantages, atomic layer deposition (ALD) methodology has attracted enormous attention in advanced LIBs. This review mainly focuses upon the up-to-date progress and development of the ALD in high-performance LIBs. The significant roles of the ALD in rational design and fabrication of multi-dimensional nanostructured electrode materials, and finely tailoring electrode-electrolyte sur-/interfaces are comprehensively highlighted. Furthermore, we clearly envision that this contribution will motivate more extensive and insightful studies in the ALD to considerably improve Li-storage behaviors. Future trends and prospects to further develop advanced ALD nanotechnology in next-generation LIBs were also presented. Full article
(This article belongs to the Special Issue New Developments in Nanomaterials for Energy Storage and Conversions)
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Open AccessFeature PaperReview Advances in Single-Chain Nanoparticles for Catalysis Applications
Nanomaterials 2017, 7(10), 341; doi:10.3390/nano7100341
Received: 28 September 2017 / Revised: 18 October 2017 / Accepted: 19 October 2017 / Published: 21 October 2017
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Abstract
Enzymes are the most efficient catalysts known for working in an aqueous environment near room temperature. The folding of individual polymer chains to functional single-chain nanoparticles (SCNPs) offers many opportunities for the development of artificial enzyme-mimic catalysts showing both high catalytic activity and
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Enzymes are the most efficient catalysts known for working in an aqueous environment near room temperature. The folding of individual polymer chains to functional single-chain nanoparticles (SCNPs) offers many opportunities for the development of artificial enzyme-mimic catalysts showing both high catalytic activity and specificity. In this review, we highlight recent results obtained in the use of SCNPs as bioinspired, highly-efficient nanoreactors (3–30 nm) for the synthesis of a variety of nanomaterials (inorganic nanoparticles, quantum dots, carbon nanodots), polymers, and chemical compounds, as well as nanocontainers for CO2 capture and release. Full article
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Other

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Open AccessCommentary Antimicrobial Nanomaterials: Why Evolution Matters
Nanomaterials 2017, 7(10), 283; doi:10.3390/nano7100283
Received: 29 August 2017 / Revised: 14 September 2017 / Accepted: 18 September 2017 / Published: 21 September 2017
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Abstract
Due to the widespread occurrence of multidrug resistant microbes there is increasing interest in the use of novel nanostructured materials as antimicrobials. Specifically, metallic nanoparticles such as silver, copper, and gold have been deployed due to the multiple impacts they have on bacterial
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Due to the widespread occurrence of multidrug resistant microbes there is increasing interest in the use of novel nanostructured materials as antimicrobials. Specifically, metallic nanoparticles such as silver, copper, and gold have been deployed due to the multiple impacts they have on bacterial physiology. From this, many have concluded that such nanomaterials represent steep obstacles against the evolution of resistance. However, we have already shown that this view is fallacious. For this reason, the significance of our initial experiments are beginning to be recognized in the antimicrobial effects of nanomaterials literature. This recognition is not yet fully understood and here we further explain why nanomaterials research requires a more nuanced understanding of core microbial evolution principles. Full article
(This article belongs to the Special Issue Antibacterial Activity of Nanomaterials)
Open AccessBrief Report An Al2O3 Gating Substrate for the Greater Performance of Field Effect Transistors Based on Two-Dimensional Materials
Nanomaterials 2017, 7(10), 286; doi:10.3390/nano7100286
Received: 14 August 2017 / Revised: 18 September 2017 / Accepted: 18 September 2017 / Published: 22 September 2017
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Abstract
We fabricated 70 nm Al2O3 gated field effect transistors based on two-dimensional (2D) materials and characterized their optical and electrical properties. Studies show that the optical contrast of monolayer graphene on an Al2O3/Si substrate is superior
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We fabricated 70 nm Al2O3 gated field effect transistors based on two-dimensional (2D) materials and characterized their optical and electrical properties. Studies show that the optical contrast of monolayer graphene on an Al2O3/Si substrate is superior to that on a traditional 300 nm SiO2/Si substrate (2.4 times). Significantly, the transconductance of monolayer graphene transistors on the Al2O3/Si substrate shows an approximately 10-fold increase, due to a smaller dielectric thickness and a higher dielectric constant. Furthermore, this substrate is also suitable for other 2D materials, such as WS2, and can enhance the transconductance remarkably by 61.3 times. These results demonstrate a new and ideal substrate for the fabrication of 2D materials-based electronic logic devices. Full article
(This article belongs to the Special Issue Graphene and Nanotube Based Devices)
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Open AccessAddendum Addendum: Shi, X.D.; Ruan, W.Q.; Hu, J.W.; Fan, M.Y.; Cao, R.S.; Wei, X.H. Optimizing the Removal of Rhodamine B in Aqueous Solutions by Reduced Graphene Oxide-Supported Nanoscale Zerovalent Iron (nZVI/rGO) Using an Artificial Neural Network-Genetic Algorithm (ANN-GA). Nanomaterials 2017, 7, 134
Nanomaterials 2017, 7(10), 309; doi:10.3390/nano7100309
Received: 27 September 2017 / Revised: 27 September 2017 / Accepted: 28 September 2017 / Published: 8 October 2017
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