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Nanomaterials, Volume 5, Issue 1 (March 2015), Pages 1-385

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Editorial

Jump to: Research, Review, Other

Open AccessEditorial Acknowledgement to Reviewers of Nanomaterials in 2014
Nanomaterials 2015, 5(1), 61-62; doi:10.3390/nano5010061
Received: 7 January 2015 / Accepted: 7 January 2015 / Published: 7 January 2015
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Abstract
The editors of Nanomaterials would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2014:[...] Full article

Research

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Open AccessArticle Synthesis, Characterization, and Mechanism of Formation of Janus-Like Nanoparticles of Tantalum Silicide-Silicon (TaSi2/Si)
Nanomaterials 2015, 5(1), 26-35; doi:10.3390/nano5010026
Received: 21 October 2014 / Accepted: 15 December 2014 / Published: 25 December 2014
Cited by 2 | PDF Full-text (688 KB) | HTML Full-text | XML Full-text
Abstract
Metal-semiconductor Janus-like nanoparticles with the composition tantalum silicide-silicon (TaSi2/Si) were synthesized for the first time by means of an evaporation method utilizing a high-power electron beam. The composition of the synthesized particles were characterized using high-resolution transmission electron microscopy (HRTEM), X-ray
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Metal-semiconductor Janus-like nanoparticles with the composition tantalum silicide-silicon (TaSi2/Si) were synthesized for the first time by means of an evaporation method utilizing a high-power electron beam. The composition of the synthesized particles were characterized using high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), selective area electron diffraction (SAED), and energy dispersive X-ray fluorescence (EDX) analysis. The system is compared to previously synthesized core-shell type particles in order to show possible differences responsible for the Janus-like structure forming instead of a core-shell architecture. It is proposed that the production of Janus-like as opposed to core-shell or monophase particles occurs due to the ability of Ta and Si to form compounds and the relative content of Ta and Si atoms in the produced vapour. Based on the results, a potential mechanism of formation for the TaSi2/Si nanoparticles is discussed. Full article
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Open AccessArticle A Novel Arch-Shape Nanogenerator Based on Piezoelectric and Triboelectric Mechanism for Mechanical Energy Harvesting
Nanomaterials 2015, 5(1), 36-46; doi:10.3390/nano5010036
Received: 26 November 2014 / Accepted: 18 December 2014 / Published: 26 December 2014
Cited by 5 | PDF Full-text (1088 KB) | HTML Full-text | XML Full-text
Abstract
A simple and cost-effective approach was developed to fabricate piezoelectric and triboelectric nanogenerator (P-TENG) with high electrical output. Additionally, pyramid micro structures fabricated atop a polydimethylsiloxane (PDMS) surface were employed to enhance the device performance. Furthermore, piezoelectric barium titanate (BT) nanoparticles and multiwalled
[...] Read more.
A simple and cost-effective approach was developed to fabricate piezoelectric and triboelectric nanogenerator (P-TENG) with high electrical output. Additionally, pyramid micro structures fabricated atop a polydimethylsiloxane (PDMS) surface were employed to enhance the device performance. Furthermore, piezoelectric barium titanate (BT) nanoparticles and multiwalled carbon nanotube (MWCNT) were mixed in the PDMS film during the forming process. Meanwhile, the composition of the film was optimized to achieve output performance, and favorable toughness was achieved after thermal curing. An arch-shape ITO/PET electrode was attached to the upper side of the polarized composite film and an aluminum film was placed under it as the bottom electrode. With periodic external force at 20 Hz, electrical output of this P-TENG, reached a peak voltage of 22 V and current of 9 μA with a peak current density of 1.13 μA/cm2, which was six times that of the triboelectric generator without BT and MWCNT nanoparticles. The nanogenerator can be directly used to lighten 28 commercial light-emitting diodes (LEDs) without any energy storage unit or rectification circuit under human footfalls. Full article
(This article belongs to the Special Issue Nanomaterials for Energy and Sustainability Applications)
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Open AccessArticle Cellular Uptake of Tile-Assembled DNA Nanotubes
Nanomaterials 2015, 5(1), 47-60; doi:10.3390/nano5010047
Received: 2 December 2014 / Accepted: 22 December 2014 / Published: 30 December 2014
Cited by 16 | PDF Full-text (1604 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
DNA-based nanostructures have received great attention as molecular vehicles for cellular delivery of biomolecules and cancer drugs. Here, we report on the cellular uptake of tubule-like DNA tile-assembled nanostructures 27 nm in length and 8 nm in diameter that carry siRNA molecules, folic
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DNA-based nanostructures have received great attention as molecular vehicles for cellular delivery of biomolecules and cancer drugs. Here, we report on the cellular uptake of tubule-like DNA tile-assembled nanostructures 27 nm in length and 8 nm in diameter that carry siRNA molecules, folic acid and fluorescent dyes. In our observations, the DNA structures are delivered to the endosome and do not reach the cytosol of the GFP-expressing HeLa cells that were used in the experiments. Consistent with this observation, no elevated silencing of the GFP gene could be detected. Furthermore, the presence of up to six molecules of folic acid on the carrier surface did not alter the uptake behavior and gene silencing. We further observed several challenges that have to be considered when performing in vitro and in vivo experiments with DNA structures: (i) DNA tile tubes consisting of 42 nt-long oligonucleotides and carrying single- or double-stranded extensions degrade within one hour in cell medium at 37 °C, while the same tubes without extensions are stable for up to eight hours. The degradation is caused mainly by the low concentration of divalent ions in the media. The lifetime in cell medium can be increased drastically by employing DNA tiles that are 84 nt long. (ii) Dyes may get cleaved from the oligonucleotides and then accumulate inside the cell close to the mitochondria, which can lead to misinterpretation of data generated by flow cytometry and fluorescence microscopy. (iii) Single-stranded DNA carrying fluorescent dyes are internalized at similar levels as the DNA tile-assembled tubes used here. Full article
(This article belongs to the Special Issue Frontiers in Nucleic Acid Nanotechnology)
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Open AccessCommunication The Nucleotide Capture Region of Alpha Hemolysin: Insights into Nanopore Design for DNA Sequencing from Molecular Dynamics Simulations
Nanomaterials 2015, 5(1), 144-153; doi:10.3390/nano5010144
Received: 26 November 2014 / Revised: 7 January 2015 / Accepted: 12 January 2015 / Published: 27 January 2015
Cited by 2 | PDF Full-text (3293 KB) | HTML Full-text | XML Full-text
Abstract
Nanopore technology for DNA sequencing is constantly being refined and improved. In strand sequencing a single strand of DNA is fed through a nanopore and subsequent fluctuations in the current are measured. A major hurdle is that the DNA is translocated through the
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Nanopore technology for DNA sequencing is constantly being refined and improved. In strand sequencing a single strand of DNA is fed through a nanopore and subsequent fluctuations in the current are measured. A major hurdle is that the DNA is translocated through the pore at a rate that is too fast for the current measurement systems. An alternative approach is “exonuclease sequencing”, in which an exonuclease is attached to the nanopore that is able to process the strand, cleaving off one base at a time. The bases then flow through the nanopore and the current is measured. This method has the advantage of potentially solving the translocation rate problem, as the speed is controlled by the exonuclease. Here we consider the practical details of exonuclease attachment to the protein alpha hemolysin. We employ molecular dynamics simulations to determine the ideal (a) distance from alpha-hemolysin, and (b) the orientation of the monophosphate nucleotides upon release from the exonuclease such that they will enter the protein. Our results indicate an almost linear decrease in the probability of entry into the protein with increasing distance of nucleotide release. The nucleotide orientation is less significant for entry into the protein. Full article
(This article belongs to the Special Issue Frontiers in Nucleic Acid Nanotechnology)
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Open AccessArticle Cysteine-Functionalized Chitosan Magnetic Nano-Based Particles for the Recovery of Light and Heavy Rare Earth Metals: Uptake Kinetics and Sorption Isotherms
Nanomaterials 2015, 5(1), 154-179; doi:10.3390/nano5010154
Received: 5 November 2014 / Revised: 16 January 2015 / Accepted: 27 January 2015 / Published: 4 February 2015
Cited by 22 | PDF Full-text (1725 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Cysteine-functionalized chitosan magnetic nano-based particles were synthesized for the sorption of light and heavy rare earth (RE) metal ions (La(III), Nd(III) and Yb(III)). The structural, surface, and magnetic properties of nano-sized sorbent were investigated by elemental analysis, FTIR, XRD, TEM and VSM (vibrating
[...] Read more.
Cysteine-functionalized chitosan magnetic nano-based particles were synthesized for the sorption of light and heavy rare earth (RE) metal ions (La(III), Nd(III) and Yb(III)). The structural, surface, and magnetic properties of nano-sized sorbent were investigated by elemental analysis, FTIR, XRD, TEM and VSM (vibrating sample magnetometry). Experimental data show that the pseudo second-order rate equation fits the kinetic profiles well, while sorption isotherms are described by the Langmuir model. Thermodynamic constants (ΔG°, ΔH°) demonstrate the spontaneous and endothermic nature of sorption. Yb(III) (heavy RE) was selectively sorbed while light RE metal ions La(III) and Nd(III) were concentrated/enriched in the solution. Cationic species RE(III) in aqueous solution can be adsorbed by the combination of chelating and anion-exchange mechanisms. The sorbent can be efficiently regenerated using acidified thiourea. Full article
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Open AccessArticle Polymorphic Ring-Shaped Molecular Clusters Made of Shape-Variable Building Blocks
Nanomaterials 2015, 5(1), 208-217; doi:10.3390/nano5010208
Received: 1 December 2014 / Revised: 26 January 2015 / Accepted: 3 February 2015 / Published: 16 February 2015
Cited by 1 | PDF Full-text (2596 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Self-assembling molecular building blocks able to dynamically change their shapes, is a concept that would offer a route to reconfigurable systems. Although simulation studies predict novel properties useful for applications in diverse fields, such kinds of building blocks, have not been implemented thus
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Self-assembling molecular building blocks able to dynamically change their shapes, is a concept that would offer a route to reconfigurable systems. Although simulation studies predict novel properties useful for applications in diverse fields, such kinds of building blocks, have not been implemented thus far with molecules. Here, we report shape-variable building blocks fabricated by DNA self-assembly. Blocks are movable enough to undergo shape transitions along geometrical ranges. Blocks connect to each other and assemble into polymorphic ring-shaped clusters via the stacking of DNA blunt-ends. Reconfiguration of the polymorphic clusters is achieved by the surface diffusion on mica substrate in response to a monovalent salt concentration. This work could inspire novel reconfigurable self-assembling systems for applications in molecular robotics. Full article
(This article belongs to the Special Issue Frontiers in Nucleic Acid Nanotechnology)
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Open AccessArticle Synthesis of Upconversion β-NaYF4:Nd3+/Yb3+/Er3+ Particles with Enhanced Luminescent Intensity through Control of Morphology and Phase
Nanomaterials 2015, 5(1), 218-232; doi:10.3390/nano5010218
Received: 27 January 2015 / Revised: 11 February 2015 / Accepted: 12 February 2015 / Published: 24 February 2015
Cited by 11 | PDF Full-text (1056 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Hexagonal NaYF4:Nd3+/Yb3+/Er3+ microcrystals and nanocrystals with well-defined morphologies and sizes have been synthesized via a hydrothermal route. The rational control of initial reaction conditions can not only result in upconversion (UC) micro and nanocrystals with varying
[...] Read more.
Hexagonal NaYF4:Nd3+/Yb3+/Er3+ microcrystals and nanocrystals with well-defined morphologies and sizes have been synthesized via a hydrothermal route. The rational control of initial reaction conditions can not only result in upconversion (UC) micro and nanocrystals with varying morphologies, but also can produce enhanced and tailored upconversion emissions from the Yb3+/Er3+ ion pairs sensitized by the Nd3+ ions. The increase of reaction time converts the phase of NaYF4:Nd3+/Yb3+/Er3+ particles from the cubic to the hexagonal structure. The added amount of oleic acid plays a critical role in the shape evolution of the final products due to their preferential attachment to some crystal planes. The adjustment of the molar ratio of F/Ln3+ can range the morphologies of the β-NaYF4:Nd3+/Yb3+/Er3+ microcrystals from spheres to nanorods. When excited by 808 nm infrared laser, β-NaYF4:Nd3+/Yb3+/Er3+ microplates exhibit a much stronger UC emission intensity than particles with other morphologies. This phase- and morphology-dependent UC emission holds promise for applications in photonic devices and biological studies. Full article
(This article belongs to the Special Issue Current Trends in Up-Converting Nanoparticles)
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Open AccessArticle DNA-Assisted Solubilization of Carbon Nanotubes and Construction of DNA-MWCNT Cross-Linked Hybrid Hydrogels
Nanomaterials 2015, 5(1), 270-283; doi:10.3390/nano5010270
Received: 22 December 2014 / Revised: 14 January 2015 / Accepted: 25 February 2015 / Published: 3 March 2015
Cited by 8 | PDF Full-text (1192 KB) | HTML Full-text | XML Full-text
Abstract
A simple method for preparation of DNA-carbon nanotubes hybrid hydrogel based on a two-step procedure including: (i) solubilization of multi-walled carbon nanotubes (MWCNT) in aqueous solution of DNA, and (ii) chemical cross-linking between solubilized MWCNT via adsorbed DNA and free DNA by ethylene
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A simple method for preparation of DNA-carbon nanotubes hybrid hydrogel based on a two-step procedure including: (i) solubilization of multi-walled carbon nanotubes (MWCNT) in aqueous solution of DNA, and (ii) chemical cross-linking between solubilized MWCNT via adsorbed DNA and free DNA by ethylene glycol diglycidyl ether is reported. We show that there exists a critical concentration of MWCNT below which a homogeneous dispersion of MWCNT in hybrid hydrogel can be achieved, while at higher concentrations of MWCNT the aggregation of MWCNT inside hydrogel occurs. The strengthening effect of carbon nanotube in the process of hydrogel shrinking in solutions with high salt concentration was demonstrated and significant passivation of MWCNT adsorption properties towards low-molecular-weight aromatic binders due to DNA adsorption on MWCNT surface was revealed. Full article
(This article belongs to the Special Issue Frontiers in Nucleic Acid Nanotechnology)
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Open AccessArticle DNA/Ag Nanoparticles as Antibacterial Agents against Gram-Negative Bacteria
Nanomaterials 2015, 5(1), 284-297; doi:10.3390/nano5010284
Received: 4 December 2014 / Revised: 20 February 2015 / Accepted: 25 February 2015 / Published: 3 March 2015
Cited by 8 | PDF Full-text (1349 KB) | HTML Full-text | XML Full-text
Abstract
Silver (Ag) nanoparticles were produced using DNA extracted from salmon milt as templates. Particles spherical in shape with an average diameter smaller than 10 nm were obtained. The nanoparticles consisted of Ag as the core with an outermost thin layer of DNA. The
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Silver (Ag) nanoparticles were produced using DNA extracted from salmon milt as templates. Particles spherical in shape with an average diameter smaller than 10 nm were obtained. The nanoparticles consisted of Ag as the core with an outermost thin layer of DNA. The DNA/Ag hybrid nanoparticles were immobilized over the surface of cotton based fabrics and their antibacterial efficiency was evaluated using E. coli as the typical Gram-negative bacteria. The antibacterial experiments were performed according to the Antibacterial Standard of Japanese Association for the Functional Evaluation of Textiles. The fabrics modified with DNA/Ag nanoparticles showed a high enough inhibitory and killing efficiency against E. coli at a concentration of Ag ≥ 10 ppm. Full article
(This article belongs to the Special Issue Frontiers in Nucleic Acid Nanotechnology)
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Open AccessArticle Chemokine-Releasing Nanoparticles for Manipulation of the Lymph Node Microenvironment
Nanomaterials 2015, 5(1), 298-320; doi:10.3390/nano5010298
Received: 9 January 2015 / Revised: 9 February 2015 / Accepted: 27 February 2015 / Published: 5 March 2015
Cited by 3 | PDF Full-text (5150 KB) | HTML Full-text | XML Full-text
Abstract
Chemokines (CKs) secreted by the host cells into surrounding tissue establish concentration gradients directing the migration of leukocytes. We propose an in vivo CK gradient remodeling approach based on sustained release of CKs by the crosslinked poly(N-isopropylacrylamide) hydrogel open meshwork nano-particles (NPs) containing
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Chemokines (CKs) secreted by the host cells into surrounding tissue establish concentration gradients directing the migration of leukocytes. We propose an in vivo CK gradient remodeling approach based on sustained release of CKs by the crosslinked poly(N-isopropylacrylamide) hydrogel open meshwork nano-particles (NPs) containing internal crosslinked dye affinity baits for a reversible CK binding and release. The sustained release is based on a new principle of affinity off-rate tuning. The NPs with Cibacron Blue F3G-A and Reactive Blue-4 baits demonstrated a low-micromolar affinity binding to IL-8, MIP-2, and MCP-1 with a half-life of several hours at 37 °C. The capacity of NPs loaded with IL-8 and MIP-1α to increase neutrophil recruitment to lymph nodes (LNs) was tested in mice after footpad injection. Fluorescently-labeled NPs used as tracers indicated the delivery into the sub-capsular compartment of draining LNs. The animals administered the CK-loaded NPs demonstrated a widening of the sub-capsular space and a strong LN influx of leukocytes, while mice injected with control NPs without CKs or bolus doses of soluble CKs alone showed only a marginal neutrophil response. This technology provides a new means to therapeutically direct or restore immune cell traffic, and can also be employed for simultaneous therapy delivery. Full article
(This article belongs to the Special Issue Nanoparticles in Theranostics)
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Open AccessArticle In Situ Self Assembly of Nanocomposites: Competition of Chaotic Advection and Interfacial Effects as Observed by X-Ray Diffreaction
Nanomaterials 2015, 5(1), 351-365; doi:10.3390/nano5010351
Received: 3 February 2015 / Revised: 16 February 2015 / Accepted: 17 February 2015 / Published: 17 March 2015
Cited by 1 | PDF Full-text (2502 KB) | HTML Full-text | XML Full-text
Abstract
The effects of chaotic advection on the in situ assembly of a hierarchal nanocomposite of Poly Amide 6, (nylon 6 or PA6) and platelet shape nanoparticles (NPs) were studied. The assemblies were formed by chaotic advection, where melts of pristine PA6 and a
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The effects of chaotic advection on the in situ assembly of a hierarchal nanocomposite of Poly Amide 6, (nylon 6 or PA6) and platelet shape nanoparticles (NPs) were studied. The assemblies were formed by chaotic advection, where melts of pristine PA6 and a mixture of PA6 with NPs were segregated into discrete layers and extruded into film in a continuous process. The process assembles the nanocomposite into alternating pristine-polymer and oriented NP/polymer layers. The structure of these hierarchal assemblies was probed by X-rays as a processing parameter, N, was varied. This parameter provides a measure of the extent of in situ structuring by chaotic advection. We found that all assemblies are semi-crystalline at room temperature. Increasing N impacts the ratio of α to γ crystalline forms. The effects of the chaotic advection vary with the concentration of the NPs. For nanocomposites with lower NP concentrations the amount of the γ crystalline form increased with N. However, at higher NP concentrations, interfacial effects of the NP play a significant role in determining the structure, where the NPs oriented along the melt flow direction and the polymer chains oriented perpendicular to the NP surfaces. Full article
(This article belongs to the Special Issue Self-Assembled Nanomaterials)
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Open AccessArticle On the Mass Fractal Character of Si-Based Structural Networks in Amorphous Polymer Derived Ceramics
Nanomaterials 2015, 5(1), 366-375; doi:10.3390/nano5010366
Received: 6 February 2015 / Revised: 7 March 2015 / Accepted: 9 March 2015 / Published: 17 March 2015
Cited by 2 | PDF Full-text (2640 KB) | HTML Full-text | XML Full-text
Abstract
The intermediate-range packing of SiNxC4−x (0 ≤ x ≤ 4) tetrahedra in polysilycarbodiimide and polysilazane-derived amorphous SiCN ceramics is investigated using 29Si spin-lattice relaxation nuclear magnetic resonance (SLR NMR) spectroscopy. The SiCN network in the polysilylcarbodiimide-derived ceramic consists
[...] Read more.
The intermediate-range packing of SiNxC4−x (0 ≤ x ≤ 4) tetrahedra in polysilycarbodiimide and polysilazane-derived amorphous SiCN ceramics is investigated using 29Si spin-lattice relaxation nuclear magnetic resonance (SLR NMR) spectroscopy. The SiCN network in the polysilylcarbodiimide-derived ceramic consists predominantly of SiN4 tetrahedra that are characterized by a 3-dimensional spatial distribution signifying compact packing of such units to form amorphous Si3N4 clusters. On the other hand, the SiCN network of the polysilazane-derived ceramic is characterized by mixed bonded SiNxC4−x tetrahedra that are inefficiently packed with a mass fractal dimension of Df ~2.5 that is significantly lower than the embedding Euclidean dimension (D = 3). This result unequivocally confirms the hypothesis that the presence of dissimilar atoms, namely, 4-coordinated C and 3-coordinated N, in the nearest neighbor environment of Si along with some exclusion in connectivity between SiCxN4−x tetrahedra with widely different N:C ratios and the absence of bonding between C and N result in steric hindrance to an efficient packing of these structural units. It is noted that similar inefficiencies in packing are observed in polymer-derived amorphous SiOC ceramics as well as in proteins and binary hard sphere systems. Full article
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Open AccessArticle Unidirectional Wave Propagation in Low-Symmetric Colloidal Photonic-Crystal Heterostructures
Nanomaterials 2015, 5(1), 376-385; doi:10.3390/nano5010376
Received: 16 January 2015 / Revised: 13 March 2015 / Accepted: 17 March 2015 / Published: 19 March 2015
Cited by 3 | PDF Full-text (4903 KB) | HTML Full-text | XML Full-text
Abstract
We show theoretically that photonic crystals consisting of colloidal spheres exhibit unidirectional wave propagation and one-way frequency band gaps without breaking time-reversal symmetry via, e.g., the application of an external magnetic field or the use of nonlinear materials. Namely, photonic crystals with low
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We show theoretically that photonic crystals consisting of colloidal spheres exhibit unidirectional wave propagation and one-way frequency band gaps without breaking time-reversal symmetry via, e.g., the application of an external magnetic field or the use of nonlinear materials. Namely, photonic crystals with low symmetry such as the monoclinic crystal type considered here as well as with unit cells formed by the heterostructure of different photonic crystals show significant unidirectional electromagnetic response. In particular, we show that the use of scatterers with low refractive-index contrast favors the formation of unidirectional frequency gaps which is the optimal route for achieving unidirectional wave propagation. Full article
(This article belongs to the Special Issue Nanophotonic Materials)
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Review

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Open AccessFeature PaperReview Rare Earth Ion-Doped Upconversion Nanocrystals: Synthesis and Surface Modification
Nanomaterials 2015, 5(1), 1-25; doi:10.3390/nano5010001
Received: 3 November 2014 / Accepted: 10 December 2014 / Published: 25 December 2014
Cited by 14 | PDF Full-text (1361 KB) | HTML Full-text | XML Full-text
Abstract
The unique luminescent properties exhibited by rare earth ion-doped upconversion nanocrystals (UCNPs), such as long lifetime, narrow emission line, high color purity, and high resistance to photobleaching, have made them widely used in many areas, including but not limited to high-resolution displays, new-generation
[...] Read more.
The unique luminescent properties exhibited by rare earth ion-doped upconversion nanocrystals (UCNPs), such as long lifetime, narrow emission line, high color purity, and high resistance to photobleaching, have made them widely used in many areas, including but not limited to high-resolution displays, new-generation information technology, optical communication, bioimaging, and therapy. However, the inherent upconversion luminescent properties of UCNPs are influenced by various parameters, including the size, shape, crystal structure, and chemical composition of the UCNPs, and even the chosen synthesis process and the surfactant molecules used. This review will provide a complete summary on the synthesis methods and the surface modification strategies of UCNPs reported so far. Firstly, we summarize the synthesis methodologies developed in the past decades, such as thermal decomposition, thermal coprecipitation, hydro/solvothermal, sol-gel, combustion, and microwave synthesis. In the second part, five main streams of surface modification strategies for converting hydrophobic UCNPs into hydrophilic ones are elaborated. Finally, we consider the likely directions of the future development and challenges of the synthesis and surface modification, such as the large-scale production and actual applications, stability, and so on, of the UCNPs. Full article
(This article belongs to the Special Issue Current Trends in Up-Converting Nanoparticles)
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Open AccessReview Magnetic Properties of Magnetic Nanoparticles for Efficient Hyperthermia
Nanomaterials 2015, 5(1), 63-89; doi:10.3390/nano5010063
Received: 15 November 2014 / Accepted: 30 December 2014 / Published: 9 January 2015
Cited by 60 | PDF Full-text (309 KB) | HTML Full-text | XML Full-text
Abstract
Localized magnetic hyperthermia using magnetic nanoparticles (MNPs) under the application of small magnetic fields is a promising tool for treating small or deep-seated tumors. For this method to be applicable, the amount of MNPs used should be minimized. Hence, it is essential to
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Localized magnetic hyperthermia using magnetic nanoparticles (MNPs) under the application of small magnetic fields is a promising tool for treating small or deep-seated tumors. For this method to be applicable, the amount of MNPs used should be minimized. Hence, it is essential to enhance the power dissipation or heating efficiency of MNPs. Several factors influence the heating efficiency of MNPs, such as the amplitude and frequency of the applied magnetic field and the structural and magnetic properties of MNPs. We discuss some of the physics principles for effective heating of MNPs focusing on the role of surface anisotropy, interface exchange anisotropy and dipolar interactions. Basic magnetic properties of MNPs such as their superparamagnetic behavior, are briefly reviewed. The influence of temperature on anisotropy and magnetization of MNPs is discussed. Recent development in self-regulated hyperthermia is briefly discussed. Some physical and practical limitations of using MNPs in magnetic hyperthermia are also briefly discussed. Full article
Open AccessReview Recent Advances on Carbon Nanotubes and Graphene Reinforced Ceramics Nanocomposites
Nanomaterials 2015, 5(1), 90-114; doi:10.3390/nano5010090
Received: 9 December 2014 / Accepted: 12 January 2015 / Published: 20 January 2015
Cited by 31 | PDF Full-text (3248 KB) | HTML Full-text | XML Full-text
Abstract
Ceramics suffer the curse of extreme brittleness and demand new design philosophies and novel concepts of manufacturing to overcome such intrinsic drawbacks, in order to take advantage of most of their excellent properties. This has been one of the foremost challenges for ceramic
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Ceramics suffer the curse of extreme brittleness and demand new design philosophies and novel concepts of manufacturing to overcome such intrinsic drawbacks, in order to take advantage of most of their excellent properties. This has been one of the foremost challenges for ceramic material experts. Tailoring the ceramics structures at nanometre level has been a leading research frontier; whilst upgrading via reinforcing ceramic matrices with nanomaterials including the latest carbon nanotubes (CNTs) and graphene has now become an eminent practice for advanced applications. Most recently, several new strategies have indeed improved the properties of the ceramics/CNT nanocomposites, such as by tuning with dopants, new dispersions routes and modified sintering methods. The utilisation of graphene in ceramic nanocomposites, either as a solo reinforcement or as a hybrid with CNTs, is the newest development. This article will summarise the recent advances, key difficulties and potential applications of the ceramics nanocomposites reinforced with CNTs and graphene. Full article
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Open AccessReview Alumina Matrix Composites with Non-Oxide Nanoparticle Addition and Enhanced Functionalities
Nanomaterials 2015, 5(1), 115-143; doi:10.3390/nano5010115
Received: 18 December 2014 / Revised: 8 January 2015 / Accepted: 15 January 2015 / Published: 27 January 2015
Cited by 6 | PDF Full-text (3684 KB) | HTML Full-text | XML Full-text
Abstract
The addition of SiC or TiC nanoparticles to polycrystalline alumina matrix has long been known as an efficient way of improving the mechanical properties of alumina-based ceramics, especially strength, creep, and wear resistance. Recently, new types of nano-additives, such as carbon nanotubes (CNT),
[...] Read more.
The addition of SiC or TiC nanoparticles to polycrystalline alumina matrix has long been known as an efficient way of improving the mechanical properties of alumina-based ceramics, especially strength, creep, and wear resistance. Recently, new types of nano-additives, such as carbon nanotubes (CNT), carbon nanofibers (CNF), and graphene sheets have been studied in order not only to improve the mechanical properties, but also to prepare materials with added functionalities, such as thermal and electrical conductivity. This paper provides a concise review of several types of alumina-based nanocomposites, evaluating the efficiency of various preparation methods and additives in terms of their influence on the properties of composites. Full article
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Open AccessReview DNA-Protected Silver Clusters for Nanophotonics
Nanomaterials 2015, 5(1), 180-207; doi:10.3390/nano5010180
Received: 16 December 2014 / Accepted: 5 February 2015 / Published: 12 February 2015
Cited by 25 | PDF Full-text (4745 KB) | HTML Full-text | XML Full-text
Abstract
DNA-protected silver clusters (AgN-DNA) possess unique fluorescence properties that depend on the specific DNA template that stabilizes the cluster. They exhibit peak emission wavelengths that range across the visible and near-IR spectrum. This wide color palette, combined with low toxicity, high
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DNA-protected silver clusters (AgN-DNA) possess unique fluorescence properties that depend on the specific DNA template that stabilizes the cluster. They exhibit peak emission wavelengths that range across the visible and near-IR spectrum. This wide color palette, combined with low toxicity, high fluorescence quantum yields of some clusters, low synthesis costs, small cluster sizes and compatibility with DNA are enabling many applications that employ AgN-DNA. Here we review what is known about the underlying composition and structure of AgN-DNA, and how these relate to the optical properties of these fascinating, hybrid biomolecule-metal cluster nanomaterials. We place AgN-DNA in the general context of ligand-stabilized metal clusters and compare their properties to those of other noble metal clusters stabilized by small molecule ligands. The methods used to isolate pure AgN-DNA for analysis of composition and for studies of solution and single-emitter optical properties are discussed. We give a brief overview of structurally sensitive chiroptical studies, both theoretical and experimental, and review experiments on bringing silver clusters of distinct size and color into nanoscale DNA assemblies. Progress towards using DNA scaffolds to assemble multi-cluster arrays is also reviewed. Full article
(This article belongs to the Special Issue Frontiers in Nucleic Acid Nanotechnology)
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Open AccessReview New Insights into Understanding Irreversible and Reversible Lithium Storage within SiOC and SiCN Ceramics
Nanomaterials 2015, 5(1), 233-245; doi:10.3390/nano5010233
Received: 5 December 2014 / Revised: 12 January 2015 / Accepted: 13 February 2015 / Published: 24 February 2015
Cited by 14 | PDF Full-text (726 KB) | HTML Full-text | XML Full-text
Abstract
Within this work we define structural properties of the silicon carbonitride (SiCN) and silicon oxycarbide (SiOC) ceramics which determine the reversible and irreversible lithium storage capacities, long cycling stability and define the major differences in the lithium storage in SiCN and SiOC. For
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Within this work we define structural properties of the silicon carbonitride (SiCN) and silicon oxycarbide (SiOC) ceramics which determine the reversible and irreversible lithium storage capacities, long cycling stability and define the major differences in the lithium storage in SiCN and SiOC. For both ceramics, we correlate the first cycle lithiation or delithiation capacity and cycling stability with the amount of SiCN/SiOC matrix or free carbon phase, respectively. The first cycle lithiation and delithiation capacities of SiOC materials do not depend on the amount of free carbon, while for SiCN the capacity increases with the amount of carbon to reach a threshold value at ~50% of carbon phase. Replacing oxygen with nitrogen renders the mixed bond Si-tetrahedra unable to sequester lithium. Lithium is more attracted by oxygen in the SiOC network due to the more ionic character of Si-O bonds. This brings about very high initial lithiation capacities, even at low carbon content. If oxygen is replaced by nitrogen, the ceramic network becomes less attractive for lithium ions due to the more covalent character of Si-N bonds and lower electron density on the nitrogen atom. This explains the significant difference in electrochemical behavior which is observed for carbon-poor SiCN and SiOC materials. Full article
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Open AccessReview DNA under Force: Mechanics, Electrostatics, and Hydration
Nanomaterials 2015, 5(1), 246-267; doi:10.3390/nano5010246
Received: 9 December 2014 / Revised: 16 January 2015 / Accepted: 12 February 2015 / Published: 25 February 2015
Cited by 4 | PDF Full-text (1633 KB) | HTML Full-text | XML Full-text
Abstract
Quantifying the basic intra- and inter-molecular forces of DNA has helped us to better understand and further predict the behavior of DNA. Single molecule technique elucidates the mechanics of DNA under applied external forces, sometimes under extreme forces. On the other hand, ensemble
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Quantifying the basic intra- and inter-molecular forces of DNA has helped us to better understand and further predict the behavior of DNA. Single molecule technique elucidates the mechanics of DNA under applied external forces, sometimes under extreme forces. On the other hand, ensemble studies of DNA molecular force allow us to extend our understanding of DNA molecules under other forces such as electrostatic and hydration forces. Using a variety of techniques, we can have a comprehensive understanding of DNA molecular forces, which is crucial in unraveling the complex DNA functions in living cells as well as in designing a system that utilizes the unique properties of DNA in nanotechnology. Full article
(This article belongs to the Special Issue Frontiers in Nucleic Acid Nanotechnology)
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Open AccessReview Hybrids of Nucleic Acids and Carbon Nanotubes for Nanobiotechnology
Nanomaterials 2015, 5(1), 321-350; doi:10.3390/nano5010321
Received: 22 January 2015 / Revised: 25 February 2015 / Accepted: 5 March 2015 / Published: 12 March 2015
Cited by 17 | PDF Full-text (1794 KB) | HTML Full-text | XML Full-text
Abstract
Recent progress in the combination of nucleic acids and carbon nanotubes (CNTs) has been briefly reviewed here. Since discovering the hybridization phenomenon of DNA molecules and CNTs in 2003, a large amount of fundamental and applied research has been carried out. Among thousands
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Recent progress in the combination of nucleic acids and carbon nanotubes (CNTs) has been briefly reviewed here. Since discovering the hybridization phenomenon of DNA molecules and CNTs in 2003, a large amount of fundamental and applied research has been carried out. Among thousands of papers published since 2003, approximately 240 papers focused on biological applications were selected and categorized based on the types of nucleic acids used, but not the types of CNTs. This survey revealed that the hybridization phenomenon is strongly affected by various factors, such as DNA sequences, and for this reason, fundamental studies on the hybridization phenomenon are important. Additionally, many research groups have proposed numerous practical applications, such as nanobiosensors. The goal of this review is to provide perspective on biological applications using hybrids of nucleic acids and CNTs. Full article
(This article belongs to the Special Issue Frontiers in Nucleic Acid Nanotechnology)
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Open AccessRetraction Retraction: Begum et al. Potential Impact of Multi-Walled Carbon Nanotubes Exposure to the Seedling Stage of Selected Plant Species. Nanomaterials 2014, 4, 203–221
Nanomaterials 2015, 5(1), 268-269; doi:10.3390/nano5010268
Received: 23 February 2015 / Revised: 23 February 2015 / Accepted: 23 February 2015 / Published: 2 March 2015
PDF Full-text (131 KB) | HTML Full-text | XML Full-text
Abstract
We have become aware that a substantial part of the main text of [1] is copied from multiple other publications. In total, 46% of the main text was taken from publications by the same authors [2,3] and 10% from other papers [4,5]. Because
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We have become aware that a substantial part of the main text of [1] is copied from multiple other publications. In total, 46% of the main text was taken from publications by the same authors [2,3] and 10% from other papers [4,5]. Because of the extent of text taken verbatim from previously published articles, we have made the decision to retract the article. All the authors of [1] have agreed to this decision. This paper is thus declared retracted and shall be marked accordingly for the scientific record.[...] Full article

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