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Nanomaterials, Volume 6, Issue 2 (February 2016)

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Research

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Open AccessArticle A Nanostructured SERS Switch Based on Molecular Beacon-Controlled Assembly of Gold Nanoparticles
Nanomaterials 2016, 6(2), 24; doi:10.3390/nano6020024
Received: 15 December 2015 / Revised: 4 January 2016 / Accepted: 5 January 2016 / Published: 22 January 2016
Cited by 2 | PDF Full-text (1976 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, highly purified and stable gold nanoparticle (AuNP) dimers connected at the two ends of DNA linkage were prepared by a versatile method. A nanostructured, surface-enhanced Raman scattering (SERS) switching sensor system was fabricated based on the controlled organization of gold
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In this paper, highly purified and stable gold nanoparticle (AuNP) dimers connected at the two ends of DNA linkage were prepared by a versatile method. A nanostructured, surface-enhanced Raman scattering (SERS) switching sensor system was fabricated based on the controlled organization of gold nanoparticles (AuNPs) by a DNA nanomachine through the controlled formation/deformation of SERS “hotspots”. This strategy not only opens opportunities in the precise engineering of gap distances in gold-gold nanostructures in a highly controllable and reproducible fashion, but also provides a unique ability to research the origin of SERS and sequence-specific DNA detection. Full article
(This article belongs to the Special Issue Nanostructured Biosensors 2016)
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Open AccessArticle Composites of Quasi-Colloidal Layered Double Hydroxide Nanoparticles and Agarose Hydrogels for Chromate Removal
Nanomaterials 2016, 6(2), 25; doi:10.3390/nano6020025
Received: 30 November 2015 / Revised: 12 January 2016 / Accepted: 21 January 2016 / Published: 26 January 2016
Cited by 2 | PDF Full-text (1487 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Composite hydrogels were prepared that consisted of quasi-colloidal layered double hydroxide (LDH) nanoparticles and agarose via the electrophoretic method, starting from three different agarose concentrations of 0.5, 1, and 2 wt/v%. The composite hydrogel was identified to have a uniform distribution of LDH
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Composite hydrogels were prepared that consisted of quasi-colloidal layered double hydroxide (LDH) nanoparticles and agarose via the electrophoretic method, starting from three different agarose concentrations of 0.5, 1, and 2 wt/v%. The composite hydrogel was identified to have a uniform distribution of LDH nanoparticles in agarose matrix. Microscopic studies revealed that the composite hydrogel had a homogeneous quasi-colloidal state of LDHs, while the simple mixture of LDH powder and agarose hydrogels did not. It was determined that agarose concentration of the starting hydrogel did not significantly influence the amount of LDH that developed in the composite. The chromate scavenging efficiency of the composite hydrogel and corresponding agarose or mixture hydrogel was evaluated with respect to time, and chromate concentration. In general, the composite hydrogels exhibited much higher chromate removal efficacy compared with agarose or mixture hydrogels. Through estimating chromate adsorption by LDH moiety in the composite or mixture hydrogel, it was suggested that the agarose component facilitated the stability and dispersibility of the quasi-colloidal state of LDH nanoparticles in the composite resulting in high adsorption efficacy. From Freundlich isotherm adsorption fitting, composites were determined to possess beneficial cooperative adsorption behavior with a high adsorption coefficient. Full article
(This article belongs to the Special Issue Current Trends in Colloidal Nanocrystals)
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Open AccessArticle Extended Superspheres for Shape Approximation of Near Polyhedral Nanoparticles and a Measure of the Degree of Polyhedrality
Nanomaterials 2016, 6(2), 27; doi:10.3390/nano6020027
Received: 15 January 2016 / Accepted: 27 January 2016 / Published: 2 February 2016
Cited by 1 | PDF Full-text (5186 KB) | HTML Full-text | XML Full-text
Abstract
Crystalline nanoparticles or nanoprecipitates with a cubic structure often have near polyhedral shapes composed of low-index planes with {100}, {111} and {110}. To consider such near polyhedral shapes, algebraic formulas of extended superspheres that can express intermediate shapes between spheres and various polyhedra
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Crystalline nanoparticles or nanoprecipitates with a cubic structure often have near polyhedral shapes composed of low-index planes with {100}, {111} and {110}. To consider such near polyhedral shapes, algebraic formulas of extended superspheres that can express intermediate shapes between spheres and various polyhedra have been presented. Four extended superspheres, (i) {100} regular-hexahedral; (ii) {111} regular-octahedral (iii) {110} rhombic-dodecahedral and (iv) {100}-{111}-{110} rhombicuboctahedral superspheres are treated in this study. A measure ∏ to indicate the degree of polyhedrality is presented to discuss shape transitions of the extended superspheres. As an application of ∏ superspherical coherent precipitate is shown. Full article
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Open AccessArticle Spectroscopic and Electrochemical Studies of Imogolite and Fe-Modified Imogolite Nanotubes
Nanomaterials 2016, 6(2), 28; doi:10.3390/nano6020028
Received: 27 November 2015 / Revised: 11 January 2016 / Accepted: 14 January 2016 / Published: 2 February 2016
Cited by 2 | PDF Full-text (1512 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Carbon nanotubes and other forms of carbon nanoparticles, as well as metal nanoparticles have been widely used in film electrochemistry because they allow for the immobilization of larger amounts of catalyst (either biological or inorganic) on the top of the modified electrodes. Nevertheless,
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Carbon nanotubes and other forms of carbon nanoparticles, as well as metal nanoparticles have been widely used in film electrochemistry because they allow for the immobilization of larger amounts of catalyst (either biological or inorganic) on the top of the modified electrodes. Nevertheless, those nanoparticles present high costs of synthesis and of separation and purification that hamper their employment. On the other hand, imogolites (Im), with the general formula (OH)3Al2O3SiOH, are naturally-occurring nanomaterials, which can be obtained from glassy volcanic ash soils and can also be synthesized at mild conditions. In this research paper, we characterize through spectroscopic techniques (i.e., fourier transform infrared spectroscopy (FTIR) spectroscopy, powder X-ray diffraction (XRD) and transmission electron microscopy (TEM)) synthetized Im and Fe-modified imogolite (Im(Fe)). Moreover, the Im and Im(Fe) were physically adsorbed on the top of a graphite electrode (GE) and were characterized electrochemically in the potential region ranging from −0.8 to 0.8 V vs. the saturated calomel electrode (SCE). When the film of the Im or of the Im(Fe) was present on the top of the electrode, the intensity of the charging/discharging current increased two-fold, but no redox activity in the absence of O2 could be appreciated. To show that Im and Im(Fe) could be used as support for catalysts, iron phthalocyanine (FePc) was adsorbed on the top of the Im or Im(Fe) film, and the electrocatalytic activity towards the O2 reduction was measured. In the presence of the Im, the measured electrocatalytic current for O2 reduction increased 30%, and the overpotential drastically decreased by almost 100 mV, proving that the Im can act as a good support for the electrocatalysts. Full article
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Open AccessArticle Simultaneous Reduction and Functionalization of Graphene Oxide by 4-Hydrazinobenzenesulfonic Acid for Polymer Nanocomposites
Nanomaterials 2016, 6(2), 29; doi:10.3390/nano6020029
Received: 17 December 2015 / Revised: 13 January 2016 / Accepted: 26 January 2016 / Published: 4 February 2016
Cited by 7 | PDF Full-text (1678 KB) | HTML Full-text | XML Full-text
Abstract
Graphene oxide (GO) was functionalized and reduced simultaneously by a new reductant, 4-hydrazinobenzenesulfonic acid (HBS), with a one-step and environmentally friendly process. The hydrophilic sulfonic acid group in HBS was grafted onto the surface of GO through a covalent bond. The successful preparation
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Graphene oxide (GO) was functionalized and reduced simultaneously by a new reductant, 4-hydrazinobenzenesulfonic acid (HBS), with a one-step and environmentally friendly process. The hydrophilic sulfonic acid group in HBS was grafted onto the surface of GO through a covalent bond. The successful preparation of HBS reduced GO (HBS-rGO) was testified by scanning electron microscope (SEM), X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectra (FTIR), X-ray photoelectron spectroscopic (XPS) and thermogravimetric analysis (TGA). The interlayer space of HBS-rGO was increased to 1.478 nm from 0.751 nm for GO, resulting in a subdued Van der Waals’ force between layers and less possibility to form aggregations. The aqueous dispersibility of graphene was improved to 13.49 mg/mL from 0.58 mg/mL after the functionalization. The viscosity of the epoxy resin based HBS-rGO composite could be regulated by an adjustment of the content of HBS-rGO. This study provides a new and applicable approach for the preparation of hydrophilic functionalized graphene, and makes it possible for the application of graphene in some functional polymer nanocomposites, such as specialty water-based coatings. Full article
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Open AccessArticle Characterization of Nanoparticle Dispersion in Red Blood Cell Suspension by the Lattice Boltzmann-Immersed Boundary Method
Nanomaterials 2016, 6(2), 30; doi:10.3390/nano6020030
Received: 16 November 2015 / Revised: 21 January 2016 / Accepted: 25 January 2016 / Published: 5 February 2016
Cited by 10 | PDF Full-text (1964 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Nanodrug-carrier delivery in the blood stream is strongly influenced by nanoparticle (NP) dispersion. This paper presents a numerical study on NP transport and dispersion in red blood cell (RBC) suspensions under shear and channel flow conditions, utilizing an immersed boundary fluid-structure interaction model
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Nanodrug-carrier delivery in the blood stream is strongly influenced by nanoparticle (NP) dispersion. This paper presents a numerical study on NP transport and dispersion in red blood cell (RBC) suspensions under shear and channel flow conditions, utilizing an immersed boundary fluid-structure interaction model with a lattice Boltzmann fluid solver, an elastic cell membrane model and a particle motion model driven by both hydrodynamic loading and Brownian dynamics. The model can capture the multiphase features of the blood flow. Simulations were performed to obtain an empirical formula to predict NP dispersion rate for a range of shear rates and cell concentrations. NP dispersion rate predictions from the formula were then compared to observations from previous experimental and numerical studies. The proposed formula is shown to accurately predict the NP dispersion rate. The simulation results also confirm previous findings that the NP dispersion rate is strongly influenced by local disturbances in the flow due to RBC motion and deformation. The proposed formula provides an efficient method for estimating the NP dispersion rate in modeling NP transport in large-scale vascular networks without explicit RBC and NP models. Full article
(This article belongs to the Special Issue Nanomaterials for Biosensing Applications)
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Open AccessArticle Effect of NaCl on the Lifetime of Micro- and Nanobubbles
Nanomaterials 2016, 6(2), 31; doi:10.3390/nano6020031
Received: 25 December 2015 / Revised: 21 January 2016 / Accepted: 2 February 2016 / Published: 5 February 2016
Cited by 8 | PDF Full-text (1609 KB) | HTML Full-text | XML Full-text
Abstract
Micro- and nanobubbles (MNBs) are potentially useful for industrial applications such as the purification of wastewater and the promotion of physiological activities of living organisms. To develop such applications, we should understand their properties and behavior, such as their lifetime and their number
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Micro- and nanobubbles (MNBs) are potentially useful for industrial applications such as the purification of wastewater and the promotion of physiological activities of living organisms. To develop such applications, we should understand their properties and behavior, such as their lifetime and their number density in solution. In the present study, we observed oxygen MNBs distributed in an electrolyte (NaCl) solution using a transmission electron microscope to analyze samples made with the freeze-fracture replica method. We found that MNBs in a 100 mM NaCl solution remain for at least 1 week, but at higher concentrations decay more quickly. To better understand their lifetimes, we compared measurements of the solution's dissolved oxygen concentration and the ζ-potential of the MNBs. Our detailed observations of transmission electron microscopy (TEM) images allows us to conclude that low concentrations of NaCl stabilize MNBs due to the ion shielding effect. However, higher concentrations accelerate their disappearance by reducing the repulsive force between MNBs. Full article
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Open AccessArticle Energy Transfer between Conjugated Colloidal Ga2O3 and CdSe/CdS Core/Shell Nanocrystals for White Light Emitting Applications
Nanomaterials 2016, 6(2), 32; doi:10.3390/nano6020032
Received: 31 December 2015 / Revised: 21 January 2016 / Accepted: 4 February 2016 / Published: 15 February 2016
Cited by 2 | PDF Full-text (3180 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Developing solid state materials capable of generating homogeneous white light in an energy efficient and resource-sustainable way is central to the design of new and improved devices for various lighting applications. Most currently-used phosphors depend on strategically important rare earth elements, and rely
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Developing solid state materials capable of generating homogeneous white light in an energy efficient and resource-sustainable way is central to the design of new and improved devices for various lighting applications. Most currently-used phosphors depend on strategically important rare earth elements, and rely on a multicomponent approach, which produces sub-optimal quality white light. Here, we report the design and preparation of a colloidal white-light emitting nanocrystal conjugate. This conjugate is obtained by linking colloidal Ga2O3 and II–VI nanocrystals in the solution phase with a short bifunctional organic molecule (thioglycolic acid). The two types of nanocrystals are electronically coupled by Förster resonance energy transfer owing to the short separation between Ga2O3 (energy donor) and core/shell CdSe/CdS (energy acceptor) nanocrystals, and the spectral overlap between the photoluminescence of the donor and the absorption of the acceptor. Using steady state and time-resolved photoluminescence spectroscopies, we quantified the contribution of the energy transfer to the photoluminescence spectral power distribution and the corresponding chromaticity of this nanocrystal conjugate. Quantitative understanding of this new system allows for tuning of the emission color and the design of quasi-single white light emitting inorganic phosphors without the use of rare-earth elements. Full article
(This article belongs to the Special Issue Current Trends in Colloidal Nanocrystals)
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Open AccessArticle EU Regulation of Nanobiocides: Challenges in Implementing the Biocidal Product Regulation (BPR)
Nanomaterials 2016, 6(2), 33; doi:10.3390/nano6020033
Received: 9 October 2015 / Revised: 28 January 2016 / Accepted: 4 February 2016 / Published: 16 February 2016
Cited by 7 | PDF Full-text (551 KB) | HTML Full-text | XML Full-text
Abstract
The Biocidal Products Regulation (BPR) contains several provisions for nanomaterials (NMs) and is the first regulation in the European Union to require specific testing and risk assessment for the NM form of a biocidal substance as a part of the information requirements. Ecotoxicological
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The Biocidal Products Regulation (BPR) contains several provisions for nanomaterials (NMs) and is the first regulation in the European Union to require specific testing and risk assessment for the NM form of a biocidal substance as a part of the information requirements. Ecotoxicological data are one of the pillars of the information requirements in the BPR, but there are currently no standard test guidelines for the ecotoxicity testing of NMs. The overall objective of this work was to investigate the implications of the introduction of nano-specific testing requirements in the BPR and to explore how these might be fulfilled in the case of copper oxide nanoparticles. While there is information and data available in the open literature that could be used to fulfill the BPR information requirements, most of the studies do not take the Organisation for Economic Co-operation and Development’s nanospecific test guidelines into consideration. This makes it difficult for companies as well as regulators to fulfill the BPR information requirements for nanomaterials. In order to enable a nanospecific risk assessment, best practices need to be developed regarding stock suspension preparation and characterization, exposure suspensions preparation, and for conducting ecotoxicological test. Full article
(This article belongs to the Special Issue Engineered Nanomaterials in the Environment)
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Open AccessCommunication Degradable Dextran Nanopolymer as a Carrier for Choline Kinase (ChoK) siRNA Cancer Therapy
Nanomaterials 2016, 6(2), 34; doi:10.3390/nano6020034
Received: 27 October 2015 / Revised: 19 January 2016 / Accepted: 4 February 2016 / Published: 22 February 2016
PDF Full-text (1289 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Although small interfering RNA (siRNA) therapy has proven to be a specific and effective treatment in cells, the delivery of siRNA is a challenge for the applications of siRNA therapy. We present a degradable dextran with amine groups as an siRNA nano-carrier. In
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Although small interfering RNA (siRNA) therapy has proven to be a specific and effective treatment in cells, the delivery of siRNA is a challenge for the applications of siRNA therapy. We present a degradable dextran with amine groups as an siRNA nano-carrier. In our nano-carrier, the amine groups are conjugated to the dextran platform through the acetal bonds, which are acid sensitive. Therefore this siRNA carrier is stable in neutral and basic conditions, while the amine groups can be cleaved and released from dextran platform under weak acid conditions (such as in endosomes). The cleavage and release of amine groups can reduce the toxicity of cationic polymer and enhance the transfection efficiency. We successfully applied this nano-carrier to deliver choline kinase (ChoK) siRNA for ChoK inhibition in cells. Full article
(This article belongs to the Special Issue Nanomaterials for Cancer Therapies)
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Review

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Open AccessReview Manufacturing Techniques and Surface Engineering of Polymer Based Nanoparticles for Targeted Drug Delivery to Cancer
Nanomaterials 2016, 6(2), 26; doi:10.3390/nano6020026
Received: 24 October 2015 / Revised: 6 January 2016 / Accepted: 19 January 2016 / Published: 1 February 2016
Cited by 2 | PDF Full-text (2340 KB) | HTML Full-text | XML Full-text
Abstract
The evolution of polymer based nanoparticles as a drug delivery carrier via pharmaceutical nano/microencapsulation has greatly promoted the development of nano- and micro-medicine in the past few decades. Poly(lactide-co-glycolide) (PLGA) and chitosan, which are biodegradable and biocompatible polymers, have been approved by both
[...] Read more.
The evolution of polymer based nanoparticles as a drug delivery carrier via pharmaceutical nano/microencapsulation has greatly promoted the development of nano- and micro-medicine in the past few decades. Poly(lactide-co-glycolide) (PLGA) and chitosan, which are biodegradable and biocompatible polymers, have been approved by both the Food & Drug Administration (FDA) and European Medicine Agency (EMA), making them ideal biomaterials that can be advanced from laboratory development to clinical oral and parental administrations. PLGA and chitosan encapsulated nanoparticles (NPs) have successfully been developed as new oral drug delivery systems with demonstrated high efficacy. This review aims to provide a comprehensive overview of the fabrication of PLGA and chitosan particulate systems using nano/microencapsulation methods, the current progress and the future outlooks of the nanoparticulate drug delivery systems. Especially, we focus on the formulations and nano/micro-encapsulation techniques using top-down techniques. It also addresses how the different phases including the organic and aqueous ones in the emulsion system interact with each other and subsequently influence the properties of the drug delivery system. Besides, surface modification strategies which can effectively engineer intrinsic physicochemical properties are summarised. Finally, future perspectives and potential directions of PLGA and chitosan nano/microencapsulated drug systems are outlined. Full article
(This article belongs to the Special Issue Nanoparticles Assisted Drug Delivery)
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