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Nanomaterials, Volume 8, Issue 5 (May 2018)

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Cover Story (view full-size image) Inorganic nanoparticle systems with an optimized coating and multifunctional character boost [...] Read more.
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Open AccessArticle Properties of Ferrite Garnet (Bi, Lu, Y)3(Fe, Ga)5O12 Thin Film Materials Prepared by RF Magnetron Sputtering
Nanomaterials 2018, 8(5), 355; https://doi.org/10.3390/nano8050355
Received: 2 May 2018 / Revised: 16 May 2018 / Accepted: 21 May 2018 / Published: 22 May 2018
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Abstract
This work is devoted to physical vapor deposition synthesis, and characterisation of bismuth and lutetium-substituted ferrite-garnet thin-film materials for magneto-optic (MO) applications. The properties of garnet thin films sputtered using a target of nominal composition type Bi0.9Lu1.85Y0.25Fe
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This work is devoted to physical vapor deposition synthesis, and characterisation of bismuth and lutetium-substituted ferrite-garnet thin-film materials for magneto-optic (MO) applications. The properties of garnet thin films sputtered using a target of nominal composition type Bi0.9Lu1.85Y0.25Fe4.0Ga1O12 are studied. By measuring the optical transmission spectra at room temperature, the optical constants and the accurate film thicknesses can be evaluated using Swanepoel’s envelope method. The refractive index data are found to be matching very closely to these derived from Cauchy’s dispersion formula for the entire spectral range between 300 and 2500 nm. The optical absorption coefficient and the extinction coefficient data are studied for both the as-deposited and annealed garnet thin-film samples. A new approach is applied to accurately derive the optical constants data simultaneously with the physical layer thickness, using a combination approach employing custom-built spectrum-fitting software in conjunction with Swanepoel’s envelope method. MO properties, such as specific Faraday rotation, MO figure of merit and MO swing factor are also investigated for several annealed garnet-phase films. Full article
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Open AccessArticle The Influence of Shape on the Output Potential of ZnO Nanostructures: Sensitivity to Parallel versus Perpendicular Forces
Nanomaterials 2018, 8(5), 354; https://doi.org/10.3390/nano8050354
Received: 3 April 2018 / Revised: 8 May 2018 / Accepted: 8 May 2018 / Published: 22 May 2018
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Abstract
With the consistent shrinking of devices, micro-systems are, nowadays, widely used in areas such as biomedics, electronics, automobiles, and measurement devices. As devices shrunk, so too did their energy consumptions, opening the way for the use of nanogenerators (NGs) as power sources. In
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With the consistent shrinking of devices, micro-systems are, nowadays, widely used in areas such as biomedics, electronics, automobiles, and measurement devices. As devices shrunk, so too did their energy consumptions, opening the way for the use of nanogenerators (NGs) as power sources. In particular, to harvest energy from an object’s motion (mechanical vibrations, torsional forces, or pressure), present NGs are mainly composed of piezoelectric materials in which, upon an applied compressive or strain force, an electrical field is produced that can be used to power a device. The focus of this work is to simulate the piezoelectric effect in different ZnO nanostructures to optimize the output potential generated by a nanodevice. In these simulations, cylindrical nanowires, nanomushrooms, and nanotrees were created, and the influence of the nanostructures’ shape on the output potential was studied as a function of applied parallel and perpendicular forces. The obtained results demonstrated that the output potential is linearly proportional to the applied force and that perpendicular forces are more efficient in all structures. However, nanotrees were found to have an increased sensitivity to parallel applied forces, which resulted in a large enhancement of the output efficiency. These results could then open a new path to increase the efficiency of piezoelectric nanogenerators. Full article
(This article belongs to the Special Issue 1D Nanostructure-Based Piezo-Generators)
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Open AccessArticle Enhanced Catalytic Reduction of 4-Nitrophenol Driven by Fe3O4-Au Magnetic Nanocomposite Interface Engineering: From Facile Preparation to Recyclable Application
Nanomaterials 2018, 8(5), 353; https://doi.org/10.3390/nano8050353
Received: 23 April 2018 / Revised: 18 May 2018 / Accepted: 18 May 2018 / Published: 22 May 2018
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Abstract
In this work, we report the enhanced catalytic reduction of 4-nitrophenol driven by Fe3O4-Au magnetic nanocomposite interface engineering. A facile solvothermal method is employed for Fe3O4 hollow microspheres and Fe3O4-Au magnetic nanocomposite
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In this work, we report the enhanced catalytic reduction of 4-nitrophenol driven by Fe3O4-Au magnetic nanocomposite interface engineering. A facile solvothermal method is employed for Fe3O4 hollow microspheres and Fe3O4-Au magnetic nanocomposite synthesis via a seed deposition process. Complementary structural, chemical composition and valence state studies validate that the as-obtained samples are formed in a pure magnetite phase. A series of characterizations including conventional scanning/transmission electron microscopy (SEM/TEM), Mössbauer spectroscopy, magnetic testing and elemental mapping is conducted to unveil the structural and physical characteristics of the developed Fe3O4-Au magnetic nanocomposites. By adjusting the quantity of Au seeds coating on the polyethyleneimine-dithiocarbamates (PEI-DTC)-modified surfaces of Fe3O4 hollow microspheres, the correlation between the amount of Au seeds and the catalytic ability of Fe3O4-Au magnetic nanocomposites for 4-nitrophenol (4-NP) is investigated systematically. Importantly, bearing remarkable recyclable features, our developed Fe3O4-Au magnetic nanocomposites can be readily separated with a magnet. Such Fe3O4-Au magnetic nanocomposites shine the light on highly efficient catalysts for 4-NP reduction at the mass production level. Full article
(This article belongs to the Special Issue Alleviating Climate Change and Pollution with Nanomaterials)
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Open AccessArticle Fabrication Flexible and Luminescent Nanofibrillated Cellulose Films with Modified SrAl2O4: Eu, Dy Phosphors via Nanoscale Silica and Aminosilane
Nanomaterials 2018, 8(5), 352; https://doi.org/10.3390/nano8050352
Received: 6 April 2018 / Revised: 2 May 2018 / Accepted: 15 May 2018 / Published: 22 May 2018
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Abstract
Flexible 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-oxidized nanofibrillated cellulose (ONFC) films with long afterglow luminescence containing modified SrAl2O4: Eu2+, Dy3+ (SAOED) phosphors were fabricated by a template method. Tetraethyl orthosilicate (TEOS) and (3-aminopropyl) trimethoxy-silane (APTMS) were employed cooperatively to
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Flexible 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-oxidized nanofibrillated cellulose (ONFC) films with long afterglow luminescence containing modified SrAl2O4: Eu2+, Dy3+ (SAOED) phosphors were fabricated by a template method. Tetraethyl orthosilicate (TEOS) and (3-aminopropyl) trimethoxy-silane (APTMS) were employed cooperatively to improve the water resistance and compatibility of the SAOED particles in the ONFC suspension. The structure and morphology after modification evidenced the formation of a superior SiO2 layer and coarse amino-compounds on the surface of the phosphors. Homogeneous dispersions containing ONFC and the modified phosphors were prepared and the interface of composite films containing the amino-modified particles showed a more closely packed structure and had less voids at the interface between the cellulose and luminescent particles than that of silica-modified phosphors. The emission spectra for luminescent films showed a slight blue shift (3.2 nm) at around 512 nm. Such flexible films with good luminescence, thermal resistance, and mechanical properties can find applications in fields like luminous flexible equipment, night indication, and portable logo or labels. Full article
(This article belongs to the Special Issue Cellulose Nanomaterials)
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Open AccessArticle Electrically Guided DNA Immobilization and Multiplexed DNA Detection with Nanoporous Gold Electrodes
Nanomaterials 2018, 8(5), 351; https://doi.org/10.3390/nano8050351
Received: 2 May 2018 / Revised: 17 May 2018 / Accepted: 18 May 2018 / Published: 21 May 2018
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Abstract
Molecular diagnostics have significantly advanced the early detection of diseases, where the electrochemical sensing of biomarkers (e.g., DNA, RNA, proteins) using multiple electrode arrays (MEAs) has shown considerable promise. Nanostructuring the electrode surface results in higher surface coverage of capture probes and more
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Molecular diagnostics have significantly advanced the early detection of diseases, where the electrochemical sensing of biomarkers (e.g., DNA, RNA, proteins) using multiple electrode arrays (MEAs) has shown considerable promise. Nanostructuring the electrode surface results in higher surface coverage of capture probes and more favorable orientation, as well as transport phenomena unique to nanoscale, ultimately leading to enhanced sensor performance. The central goal of this study is to investigate the influence of electrode nanostructure on electrically-guided immobilization of DNA probes for nucleic acid detection in a multiplexed format. To that end, we used nanoporous gold (np-Au) electrodes that reduced the limit of detection (LOD) for DNA targets by two orders of magnitude compared to their planar counterparts, where the LOD was further improved by an additional order of magnitude after reducing the electrode diameter. The reduced electrode diameter also made it possible to create a np-Au MEA encapsulated in a microfluidic channel. The electro-grafting reduced the necessary incubation time to immobilize DNA probes into the porous electrodes down to 10 min (25-fold reduction compared to passive immobilization) and allowed for grafting a different DNA probe sequence onto each electrode in the array. The resulting platform was successfully used for the multiplexed detection of three different biomarker genes relevant to breast cancer diagnosis. Full article
(This article belongs to the Special Issue Nanoporous Gold and Other Related Materials)
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Open AccessArticle Performance Assessment of Ordered Porous Electrospun Honeycomb Fibers for the Removal of Atmospheric Polar Volatile Organic Compounds
Nanomaterials 2018, 8(5), 350; https://doi.org/10.3390/nano8050350
Received: 16 April 2018 / Revised: 14 May 2018 / Accepted: 15 May 2018 / Published: 21 May 2018
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Abstract
This study explored a new facile method of preparing ordered porous electrospun honeycomb fibers to obtain the most promising composites for maximal adsorption of volatile organic compounds (VOCs). The self-assembly ordered porous material (OPM) and polyacrylonitrile (PAN) were formulated into a blend solution
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This study explored a new facile method of preparing ordered porous electrospun honeycomb fibers to obtain the most promising composites for maximal adsorption of volatile organic compounds (VOCs). The self-assembly ordered porous material (OPM) and polyacrylonitrile (PAN) were formulated into a blend solution to prepare honeycomb fibers. SEM and TEM images showed that OPM was effectively bonded in PAN fibers because of the composite’s structure. Acetone was used as a model to assess the VOC adsorption performances of electrospun honeycomb fibers with different OPM contents. Experimental results revealed that the adsorption capacity of honeycomb fibers increased with the increase of loaded OPM within the PAN fibers. The highest adsorption capacity was 58.2 μg g−1 by the fibers containing with 60% OPM in weight. After several recycling times, the adsorption capacities of the reused honeycomb fibers were almost the same with the fresh fibers. This finding indicated that the electrospun honeycomb fibers have potential application in removing VOCs in the workplace, and promote the performance of masks for odor removal. Full article
(This article belongs to the Special Issue Functional Nanomaterials by Electrospinning)
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Open AccessReview Graphene-Based Nanomaterials for Tissue Engineering in the Dental Field
Nanomaterials 2018, 8(5), 349; https://doi.org/10.3390/nano8050349
Received: 3 May 2018 / Revised: 16 May 2018 / Accepted: 17 May 2018 / Published: 20 May 2018
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Abstract
The world of dentistry is approaching graphene-based nanomaterials as substitutes for tissue engineering. Apart from its exceptional mechanical strength, electrical conductivity and thermal stability, graphene and its derivatives can be functionalized with several bioactive molecules. They can also be incorporated into different scaffolds
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The world of dentistry is approaching graphene-based nanomaterials as substitutes for tissue engineering. Apart from its exceptional mechanical strength, electrical conductivity and thermal stability, graphene and its derivatives can be functionalized with several bioactive molecules. They can also be incorporated into different scaffolds used in regenerative dentistry, generating nanocomposites with improved characteristics. This review presents the state of the art of graphene-based nanomaterial applications in the dental field. We first discuss the interactions between cells and graphene, summarizing the available in vitro and in vivo studies concerning graphene biocompatibility and cytotoxicity. We then highlight the role of graphene-based nanomaterials in stem cell control, in terms of adhesion, proliferation and differentiation. Particular attention will be given to stem cells of dental origin, such as those isolated from dental pulp, periodontal ligament or dental follicle. The review then discusses the interactions between graphene-based nanomaterials with cells of the immune system; we also focus on the antibacterial activity of graphene nanomaterials. In the last section, we offer our perspectives on the various opportunities facing the use of graphene and its derivatives in associations with titanium dental implants, membranes for bone regeneration, resins, cements and adhesives as well as for tooth-whitening procedures. Full article
(This article belongs to the Special Issue Tissue Engineering and Regenerative Nanomedicine)
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Open AccessArticle Finite Element Analysis of Electrospun Nanofibrous Mats under Biaxial Tension
Nanomaterials 2018, 8(5), 348; https://doi.org/10.3390/nano8050348
Received: 30 April 2018 / Revised: 16 May 2018 / Accepted: 16 May 2018 / Published: 19 May 2018
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Abstract
Due to the non-uniform material properties of electrospun nanofibrous mats and the non-linear characteristics of single fibers, establishing a numerical model that can fully explain these features and correctly describe their properties is difficult. Based on the microstructure of electrospun nanofibrous mats, two
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Due to the non-uniform material properties of electrospun nanofibrous mats and the non-linear characteristics of single fibers, establishing a numerical model that can fully explain these features and correctly describe their properties is difficult. Based on the microstructure of electrospun nanofibrous mats, two macroscopic continuum finite element (FE) models with a uniform or oriented nanofiber distribution were established to describe the mechanical behavior of nanofibrous mats under biaxial tension. The FE models were verified by biaxial tension experiments on silk fibroin/polycaprolactone nanofibrous mats. The developed FE models expressed the mechanical behaviors of the mats under biaxial tension well. These models can help clarify the structure–property relationship of electrospun nanofibrous mats and guide the design of materials for engineering applications. Full article
(This article belongs to the Special Issue Functional Nanomaterials by Electrospinning)
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Open AccessArticle Loading of Indocyanine Green within Polydopamine-Coated Laponite Nanodisks for Targeted Cancer Photothermal and Photodynamic Therapy
Nanomaterials 2018, 8(5), 347; https://doi.org/10.3390/nano8050347
Received: 14 April 2018 / Revised: 5 May 2018 / Accepted: 15 May 2018 / Published: 19 May 2018
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Abstract
The combination of photothermal therapy (PTT) and photodynamic therapy (PDT) in cancer treatment has attracted much attention in recent years. However, developing highly efficient and targeted therapeutic nanoagents for amplifying PTT and PDT treatments remains challenging. In this work, we developed a novel
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The combination of photothermal therapy (PTT) and photodynamic therapy (PDT) in cancer treatment has attracted much attention in recent years. However, developing highly efficient and targeted therapeutic nanoagents for amplifying PTT and PDT treatments remains challenging. In this work, we developed a novel photothermal and photodynamic therapeutic nanoplatform for treatment of cancer cells overexpressing integrin αvβ3 through the coating of polydopamine (PDA) on indocyanine green (ICG)-loaded laponite (LAP) and then further conjugating polyethylene glycol-arginine-glycine-aspartic acid (PEG-RGD) as targeted agents on the surface. The ICG/LAP–PDA–PEG–RGD (ILPR) nanoparticles (NPs) formed could load ICG with a high encapsulation efficiency of 94.1%, improve the photostability of loaded ICG dramatically via the protection of PDA and LAP, and display excellent colloidal stability and biocompatibility due to the PEGylation. Under near-infrared (NIR) laser irradiation, the ILPR NPs could exert enhanced photothermal conversion reproducibly and generate reactive oxygen species (ROS) efficiently. More importantly, in vitro experiments proved that ILPR NPs could specifically target cancer cells overexpressing integrin αvβ3, enhance cellular uptake due to RGD-mediated targeting, and exert improved photothermal and photodynamic killing efficiency against targeted cells under NIR laser irradiation. Therefore, ILPR may be used as effective therapeutic nanoagents with enhanced photothermal conversion performance and ROS generating ability for targeted PTT and PDT treatment of cancer cells with integrin αvβ3 overexpressed. Full article
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Open AccessReview Synthesis of Alkanethiolate-Capped Metal Nanoparticles Using Alkyl Thiosulfate Ligand Precursors: A Method to Generate Promising Reagents for Selective Catalysis
Nanomaterials 2018, 8(5), 346; https://doi.org/10.3390/nano8050346
Received: 19 April 2018 / Revised: 15 May 2018 / Accepted: 15 May 2018 / Published: 18 May 2018
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Abstract
Evaluation of metal nanoparticle catalysts functionalized with well-defined thiolate ligands can be potentially important because such systems can provide a spatial control in the reactivity and selectivity of catalysts. A synthetic method utilizing Bunte salts (sodium S-alkylthiosulfates) allows the formation of metal
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Evaluation of metal nanoparticle catalysts functionalized with well-defined thiolate ligands can be potentially important because such systems can provide a spatial control in the reactivity and selectivity of catalysts. A synthetic method utilizing Bunte salts (sodium S-alkylthiosulfates) allows the formation of metal nanoparticles (Au, Ag, Pd, Pt, and Ir) capped with alkanethiolate ligands. The catalysis studies on Pd nanoparticles show a strong correlation between the surface ligand structure/composition and the catalytic activity and selectivity for the hydrogenation/isomerization of alkenes, dienes, trienes, and allylic alcohols. The high selectivity of Pd nanoparticles is driven by the controlled electronic properties of the Pd surface limiting the formation of Pd–alkene adducts (or intermediates) necessary for (additional) hydrogenation. The synthesis of water soluble Pd nanoparticles using ω-carboxylate-S-alkanethiosulfate salts is successfully achieved and these Pd nanoparticles are examined for the hydrogenation of various unsaturated compounds in both homogeneous and heterogeneous environments. Alkanethiolate-capped Pt nanoparticles are also successfully synthesized and further investigated for the hydrogenation of various alkynes to understand their geometric and electronic surface properties. The high catalytic activity of activated terminal alkynes, but the significantly low activity of internal alkynes and unactivated terminal alkynes, are observed for Pt nanoparticles. Full article
(This article belongs to the Special Issue Synthesis of Ligand-Capped Nanoparticles for Catalysis)
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Open AccessArticle Three-Dimensional Bi2Te3 Networks of Interconnected Nanowires: Synthesis and Optimization
Nanomaterials 2018, 8(5), 345; https://doi.org/10.3390/nano8050345
Received: 3 May 2018 / Revised: 8 May 2018 / Accepted: 10 May 2018 / Published: 18 May 2018
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Abstract
Self-standing Bi2Te3 networks of interconnected nanowires were fabricated in three-dimensional porous anodic alumina templates (3D–AAO) with a porous structure spreading in all three spatial dimensions. Pulsed electrodeposition parameters were optimized to grow highly oriented Bi2Te3 interconnected nanowires
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Self-standing Bi2Te3 networks of interconnected nanowires were fabricated in three-dimensional porous anodic alumina templates (3D–AAO) with a porous structure spreading in all three spatial dimensions. Pulsed electrodeposition parameters were optimized to grow highly oriented Bi2Te3 interconnected nanowires with stoichiometric composition inside those 3D–AAO templates. The nanowire networks were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and Raman spectroscopy. The results are compared to those obtained in films and 1D nanowires grown under similar conditions. The crystalline structure and composition of the 3D Bi–Te nanowire network are finely tuned by controlling the applied voltage and the relaxation time off at zero current density during the deposition. With this fabrication method, and controlling the electrodeposition parameters, stoichiometric Bi2Te3 networks of interconnected nanowires have been obtained, with a preferential orientation along [1 1 0], which makes them optimal candidates for out-of-plane thermoelectric applications. Moreover, the templates in which they are grown can be dissolved and the network of interconnected nanowires is self-standing without affecting its composition and orientation properties. Full article
(This article belongs to the Special Issue Synthesis and Characterization of Nanowires)
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Open AccessFeature PaperReview Recent Progress in Upconversion Photodynamic Therapy
Nanomaterials 2018, 8(5), 344; https://doi.org/10.3390/nano8050344
Received: 17 April 2018 / Revised: 10 May 2018 / Accepted: 17 May 2018 / Published: 18 May 2018
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Abstract
Photodynamic therapy (PDT) is a minimally invasive cancer modality that combines a photosensitizer (PS), light, and oxygen. Introduction of new nanotechnologies holds potential to improve PDT performance. Upconversion nanoparticles (UCNPs) offer potentially advantageous benefits for PDT, attributed to their distinct photon upconverting feature.
[...] Read more.
Photodynamic therapy (PDT) is a minimally invasive cancer modality that combines a photosensitizer (PS), light, and oxygen. Introduction of new nanotechnologies holds potential to improve PDT performance. Upconversion nanoparticles (UCNPs) offer potentially advantageous benefits for PDT, attributed to their distinct photon upconverting feature. The ability to convert near-infrared (NIR) light into visible or even ultraviolet light via UCNPs allows for the activation of nearby PS agents to produce singlet oxygen, as most PS agents absorb visible and ultraviolet light. The use of a longer NIR wavelength permits light to penetrate deeper into tissue, and thus PDT of a deeper tissue can be effectively achieved with the incorporation of UCNPs. Recent progress in UCNP development has generated the possibility to employ a wide variety of NIR excitation sources in PDT. Use of UCNPs enables concurrent strategies for loading, targeting, and controlling the release of additional drugs. In this review article, recent progress in the development of UCNPs for PDT applications is summarized. Full article
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Open AccessArticle Effect of Microwave Radiation Power on the Size of Aggregates of ZnO NPs Prepared Using Microwave Solvothermal Synthesis
Nanomaterials 2018, 8(5), 343; https://doi.org/10.3390/nano8050343
Received: 26 April 2018 / Revised: 14 May 2018 / Accepted: 15 May 2018 / Published: 18 May 2018
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Abstract
This paper reports the possibility of changing the size of zinc oxide nanoparticles (ZnO NPs) aggregates through a change of synthesis parameters. The effect of the changed power of microwave heating on the properties of ZnO NPs obtained by the microwave solvothermal synthesis
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This paper reports the possibility of changing the size of zinc oxide nanoparticles (ZnO NPs) aggregates through a change of synthesis parameters. The effect of the changed power of microwave heating on the properties of ZnO NPs obtained by the microwave solvothermal synthesis from zinc acetate dissolved in ethylene glycol was tested for the first time. It was found that the size of ZnO aggregates ranged from 60 to 120 nm depending on the power of microwave radiation used in the synthesis of ZnO NPs. The increase in the microwave radiation power resulted in the reduction of the total synthesis time with simultaneous preservation of the constant size and shape of single ZnO NPs, which were synthesized at a pressure of 4 bar. All the obtained ZnO NPs samples were composed of homogeneous spherical particles that were single crystals with an average size of 27 ± 3 nm with a developed specific surface area of 40 m2/g and the skeleton density of 5.18 ± 0.03 g/cm3. A model of a mechanism explaining the correlation between the size of aggregates and the power of microwaves was proposed. This method of controlling the average size of ZnO NPs aggregates is presented for the first time and similar investigations are not found in the literature. Full article
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Open AccessReview Doped Carbon Dots for Sensing and Bioimaging Applications: A Minireview
Nanomaterials 2018, 8(5), 342; https://doi.org/10.3390/nano8050342
Received: 3 May 2018 / Revised: 15 May 2018 / Accepted: 15 May 2018 / Published: 18 May 2018
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Abstract
In the last decade, carbon dots (C-dots, CDs) or carbon quantum dots (CQDs) have attracted a considerable amount of attention from the scientific community as a low cost and biocompatible alternative to semiconductor quantum dots. In particular, doped C-dots have excellent fluorescent properties
[...] Read more.
In the last decade, carbon dots (C-dots, CDs) or carbon quantum dots (CQDs) have attracted a considerable amount of attention from the scientific community as a low cost and biocompatible alternative to semiconductor quantum dots. In particular, doped C-dots have excellent fluorescent properties that have been successfully utilized for numerous applications. In this minireview, we overview the recent advances on the synthesis of doped C-dots derived from carbon-rich sources and their potential applications for biomedical and sensing applications. In addition, we will also discuss some challenges and outline some future perspectives of this exciting material. Full article
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Open AccessArticle The Effect of Light Intensity, Temperature, and Oxygen Pressure on the Photo-Oxidation Rate of Bare PbS Quantum Dots
Nanomaterials 2018, 8(5), 341; https://doi.org/10.3390/nano8050341
Received: 17 April 2018 / Revised: 11 May 2018 / Accepted: 14 May 2018 / Published: 18 May 2018
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Abstract
The oxidation speed of PbS quantum dots has been a subject of controversy for some time. In this study, we reveal the precise functional form of the oxidation rate constant for bare quantum dots through analysis of their photoluminescence as a function of
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The oxidation speed of PbS quantum dots has been a subject of controversy for some time. In this study, we reveal the precise functional form of the oxidation rate constant for bare quantum dots through analysis of their photoluminescence as a function of temperature, oxygen pressure, and excitation-laser intensity. The combined effect of these factors results in a reduced energy barrier that allows the oxidation to proceed at a high rate. Each absorbed photon is found to have a 10−8 probability of oxidizing a PbS atomic pair. This highlights the importance of photo-excitation on the speed of the oxidation process, even at low illumination conditions. The procedure used here may set up a quantitative standard useful for characterizing the stability of quantum dots coated with ligands/linkers, and to compare different protection schemes in a fair quantitative way. Full article
(This article belongs to the Special Issue Nanomaterials for Renewable and Sustainable Energy)
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Open AccessArticle Wetting Behaviors of a Nano-Droplet on a Rough Solid Substrate under Perpendicular Electric Field
Nanomaterials 2018, 8(5), 340; https://doi.org/10.3390/nano8050340
Received: 27 April 2018 / Revised: 14 May 2018 / Accepted: 15 May 2018 / Published: 17 May 2018
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Abstract
Molecular dynamic simulations were adopted to study the wetting properties of nanoscale droplets on rough silicon solid substrate subject to perpendicular electric fields. The effect of roughness factor and electric field strength on the static and dynamic wetting behaviors of a nano-droplet on
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Molecular dynamic simulations were adopted to study the wetting properties of nanoscale droplets on rough silicon solid substrate subject to perpendicular electric fields. The effect of roughness factor and electric field strength on the static and dynamic wetting behaviors of a nano-droplet on a solid surface was investigated at the molecular level. Results show that the static contact angle tends to decrease slightly and show small difference with the increase of roughness factor, while it shows an obvious increase for the ramp-shaped surface because the appearing bottom space reduces the wettability of solid surface. Additionally, under the electric field, a nano-droplet was elongated in the field direction and the equilibrium contact angle increases with the increase of electric field strength. The nano-droplet was completely stretched to be column-shaped at a threshold value of the field. Besides, accompanied by the shape variation of water droplets, the molecular dipole orientations of water molecules experience a remarkable change from a random disordered distribution to an ordered profile because of the realignment of water molecules induced by electric fields. Full article
(This article belongs to the Special Issue Wetting of Nanostructured Materials)
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Open AccessArticle pH-Responsive Mercaptoundecanoic Acid Functionalized Gold Nanoparticles and Applications in Catalysis
Nanomaterials 2018, 8(5), 339; https://doi.org/10.3390/nano8050339
Received: 18 April 2018 / Revised: 14 May 2018 / Accepted: 15 May 2018 / Published: 17 May 2018
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Abstract
Mercaptoundecanoic acid (MUA) functionalized gold nanoparticles (AuNP-MUA) were synthesized and demonstrated to possess pH-triggered aggregation and re-dispersion, as well as the capability of phase transfer between aqueous and organic phases in response to changes in pH. The pH of aggregation for AuNP-MUA is
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Mercaptoundecanoic acid (MUA) functionalized gold nanoparticles (AuNP-MUA) were synthesized and demonstrated to possess pH-triggered aggregation and re-dispersion, as well as the capability of phase transfer between aqueous and organic phases in response to changes in pH. The pH of aggregation for AuNP-MUA is consistent with the pKa of MUA (pH ~4) in solution, while AuNP-MUA phase transition between aqueous and organic phases occurs at pH ~9. The ion pair formation between the amine group in octadecylamine (ODA), the carboxylate group in MUA, and the hydrophobic alkyl chain of ODA facilitates the phase transfer of AuNP-MUA into an organic medium. The AuNP-MUA were investigated as a reusable catalyst in the catalytic reduction of 4-nitrophenol by borohydride—a model reaction for AuNPs. It was determined that 100% MUA surface coverage completely inhibits the catalytic activity of AuNPs. Decreasing the surface coverage was shown to increase catalytic activity, but this decrease also leads to decreased colloidal stability, recoverability, and reusability in subsequent reactions. At 60% MUA surface coverage, colloidal stability and catalytic activity were achieved, but the surface coverage was insufficient to enable redispersion following pH-induced recovery. A balance between AuNP colloidal stability, recoverability, and catalytic activity with reusability was achieved at 90% MUA surface coverage. The AuNP-MUA catalyst can also be recovered at different pH ranges depending on the recovery method employed. At pH ~4, protonation of the MUA results in reduced surface charge and aggregation. At pH ~9, ODA will form an ion-pair with the MUA and induce phase transfer into an immiscible organic phase. Both the pH-triggered aggregation/re-dispersion and aqueous/organic phase transfer methods were employed for catalyst recovery and reuse in subsequent reactions. The ability to recover and reuse the AuNP-MUA catalyst by two different methods and different pH regimes is significant, based on the fact that nanoparticle-catalyzed reactions may occur under different pH conditions. Full article
(This article belongs to the Special Issue Synthesis of Ligand-Capped Nanoparticles for Catalysis)
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Open AccessArticle Effective NiMn Nanoparticles-Functionalized Carbon Felt as an Effective Anode for Direct Urea Fuel Cells
Nanomaterials 2018, 8(5), 338; https://doi.org/10.3390/nano8050338
Received: 16 March 2018 / Revised: 7 May 2018 / Accepted: 14 May 2018 / Published: 16 May 2018
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Abstract
The internal resistances of fuel cells strongly affect the generated power. Basically, in the fuel cell, the anode can be prepared by deposition of a film from the functional electrocatalyst on a proper gas diffusion layer. Accordingly, an interfacial resistance for the electron
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The internal resistances of fuel cells strongly affect the generated power. Basically, in the fuel cell, the anode can be prepared by deposition of a film from the functional electrocatalyst on a proper gas diffusion layer. Accordingly, an interfacial resistance for the electron transport is created between the two layers. Electrocatalyst-functionalized gas diffusion layer (GDL) can distinctly reduce the interfacial resistance between the catalyst layer and the GDL. In this study, NiMn nanoparticles-decorated carbon felt is introduced as functionalized GDL to be exploited as a ready-made anode in a direct urea fuel cell. The proposed treated GDL was prepared by calcination of nickel acetate/manganese acetate-loaded carbon felt under an argon atmosphere at 850 °C. The physiochemical characterizations confirmed complete reduction for the utilized precursors and deposition of pristine NiMn nanoparticles on the carbon felt fiber. In passive direct urea fuel cells, investigation the performance of the functionalized GDLs indicated that the composition of the metal nanoparticles has to be optimized as the GDL obtained from 40 wt % manganese acetate reveals the maximum generated power density; 36 mW/m2 at room temperature and 0.5 M urea solution. Moreover, the electrochemical measurements proved that low urea solution concentration is preferred as utilizing 0.5 M solution resulted into generating higher power compared to 1.0 and 2.0 M solution. Overall, this study opens a new avenue toward functionalization of the GDL as a novel strategy to overcome the interfacial resistance between the electrocatalyst and the GDL. Full article
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Open AccessReview Periodontal Tissues, Maxillary Jaw Bone, and Tooth Regeneration Approaches: From Animal Models Analyses to Clinical Applications
Nanomaterials 2018, 8(5), 337; https://doi.org/10.3390/nano8050337
Received: 24 April 2018 / Revised: 14 May 2018 / Accepted: 15 May 2018 / Published: 16 May 2018
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Abstract
This review encompasses different pre-clinical bioengineering approaches for periodontal tissues, maxillary jaw bone, and the entire tooth. Moreover, it sheds light on their potential clinical therapeutic applications in the field of regenerative medicine. Herein, the electrospinning method for the synthesis of polycaprolactone (PCL)
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This review encompasses different pre-clinical bioengineering approaches for periodontal tissues, maxillary jaw bone, and the entire tooth. Moreover, it sheds light on their potential clinical therapeutic applications in the field of regenerative medicine. Herein, the electrospinning method for the synthesis of polycaprolactone (PCL) membranes, that are capable of mimicking the extracellular matrix (ECM), has been described. Furthermore, their functionalization with cyclosporine A (CsA), bone morphogenetic protein-2 (BMP-2), or anti-inflammatory drugs’ nanoreservoirs has been demonstrated to induce a localized and targeted action of these molecules after implantation in the maxillary jaw bone. Firstly, periodontal wound healing has been studied in an induced periodontal lesion in mice using an ibuprofen-functionalized PCL membrane. Thereafter, the kinetics of maxillary bone regeneration in a pre-clinical mouse model of surgical bone lesion treated with BMP-2 or BMP-2/Ibuprofen functionalized PCL membranes have been analyzed by histology, immunology, and micro-computed tomography (micro-CT). Furthermore, the achievement of innervation in bioengineered teeth has also been demonstrated after the co-implantation of cultured dental cell reassociations with a trigeminal ganglia (TG) and the cyclosporine A (CsA)-loaded poly(lactic-co-glycolic acid) (PLGA) scaffold in the jaw bone. The prospective clinical applications of these different tissue engineering approaches could be instrumental in the treatment of various periodontal diseases, congenital dental or cranio-facial bone anomalies, and post-surgical complications. Full article
(This article belongs to the Special Issue Preparation and Application of Hybrid Nanomaterials)
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Open AccessArticle Fabrication and Characterization of Nanoenergetic Hollow Spherical Hexanitrostibene (HNS) Derivatives
Nanomaterials 2018, 8(5), 336; https://doi.org/10.3390/nano8050336
Received: 28 April 2018 / Revised: 13 May 2018 / Accepted: 14 May 2018 / Published: 16 May 2018
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Abstract
The spherization of nanoenergetic materials is the best way to improve the sensitivity and increase loading densities and detonation properties for weapons and ammunition, but the preparation of spherical nanoenergetic materials with high regularization, uniform size and monodispersity is still a challenge. In
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The spherization of nanoenergetic materials is the best way to improve the sensitivity and increase loading densities and detonation properties for weapons and ammunition, but the preparation of spherical nanoenergetic materials with high regularization, uniform size and monodispersity is still a challenge. In this paper, nanoenergetic hollow spherical hexanitrostibene (HNS) derivatives were fabricated via a one-pot copolymerization strategy, which is based on the reaction of HNS and piperazine in acetonitrile solution. Characterization results indicated the as-prepared reaction nanoenergetic products were HNS-derived oligomers, where a free radical copolymerization reaction process was inferred. The hollow sphere structure of the HNS derivatives was characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM), and synchrotron radiation X-ray imaging technology. The properties of the nanoenergetic hollow spherical derivatives, including thermal decomposition and sensitivity are discussed in detail. Sensitivity studies showed that the nanoenergetic derivatives exhibited lower impact, friction and spark sensitivity than raw HNS. Thermogravimetric-differential scanning calorimeter (TG-DSC) results showed that continuous exothermic decomposition occurred in the whole temperature range, which indicated that nanoenergetic derivatives have a unique role in thermal applications. Therefore, nanoenergetic hollow spherical HNS derivatives could provide a new way to modify the properties of certain energetic compounds and fabricate spherical nanomaterials to improve the charge configuration. Full article
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Open AccessArticle High Performance of Supercapacitor from PEDOT:PSS Electrode and Redox Iodide Ion Electrolyte
Nanomaterials 2018, 8(5), 335; https://doi.org/10.3390/nano8050335
Received: 18 April 2018 / Revised: 5 May 2018 / Accepted: 9 May 2018 / Published: 16 May 2018
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Abstract
Insufficient energy density and poor cyclic stability is still challenge for conductive polymer-based supercapacitor. Herein, high performance electrochemical system has been assembled by combining poly (3,4-ethylenedioxythiophene) (PEDOT):poly (styrene sulfonate) (PSS) redox electrode and potassium iodide redox electrolyte, which provide the maximum specific capacity
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Insufficient energy density and poor cyclic stability is still challenge for conductive polymer-based supercapacitor. Herein, high performance electrochemical system has been assembled by combining poly (3,4-ethylenedioxythiophene) (PEDOT):poly (styrene sulfonate) (PSS) redox electrode and potassium iodide redox electrolyte, which provide the maximum specific capacity of 51.3 mAh/g and the retention of specific capacity of 87.6% after 3000 cycles due to the synergic effect through a simultaneous redox reaction both in electrode and electrolyte, as well as the catalytic activity for reduction of triiodide of the PEDOT:PSS. Full article
(This article belongs to the Special Issue Three-dimensional Nanomaterials for Energy Storage and Conversions)
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Open AccessArticle An Innovative Porous Nanocomposite Material for the Removal of Phenolic Compounds from Aqueous Solutions
Nanomaterials 2018, 8(5), 334; https://doi.org/10.3390/nano8050334
Received: 3 May 2018 / Revised: 11 May 2018 / Accepted: 14 May 2018 / Published: 16 May 2018
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Abstract
Energy efficient, low-cost, user-friendly, and green methods for the removal of toxic phenolic compounds from aqueous solution are necessary for waste treatment in industrial applications. Herein we present an interesting approach for the utilization of oxidized carbon nanotubes (CNTs) in the removal of
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Energy efficient, low-cost, user-friendly, and green methods for the removal of toxic phenolic compounds from aqueous solution are necessary for waste treatment in industrial applications. Herein we present an interesting approach for the utilization of oxidized carbon nanotubes (CNTs) in the removal of phenolic compounds from aqueous solution. Dried pristine CNTs were stably incorporated in a solid porous support of polydimethylsiloxane (PDMS) facilitating the handling during both oxidation process of the nanomaterial and uptake of phenolic compounds, and enabling their safe disposal, avoiding expensive post-treatment processes. The adsorption studies indicated that the materials can efficiently remove phenolic compounds from water with different affinities towards different phenolic compounds. Furthermore, the adsorption kinetics and isotherms were studied in detail. The experimental data of adsorption fitted well with Langmuir and Freundlich isotherms, and pseudo-second-order kinetics, and the results indicated that the adsorption process was controlled by a two-step intraparticle diffusion model. The incorporation of CNTs in polymeric matrices did not affect their functionality in phenol uptake. The material was also successfully used for the removal of phenolic compounds from agricultural waste, suggesting its possible application in the treatment of wastewater. Moreover, the surface of the material could be regenerated, decreasing treatment costs. Full article
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Open AccessArticle High-Efficiency Visible Transmitting Polarizations Devices Based on the GaN Metasurface
Nanomaterials 2018, 8(5), 333; https://doi.org/10.3390/nano8050333
Received: 29 April 2018 / Revised: 9 May 2018 / Accepted: 10 May 2018 / Published: 15 May 2018
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Abstract
Metasurfaces are capable of tailoring the amplitude, phase, and polarization of incident light to design various polarization devices. Here, we propose a metasurface based on the novel dielectric material gallium nitride (GaN) to realize high-efficiency modulation for both of the orthogonal linear polarizations
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Metasurfaces are capable of tailoring the amplitude, phase, and polarization of incident light to design various polarization devices. Here, we propose a metasurface based on the novel dielectric material gallium nitride (GaN) to realize high-efficiency modulation for both of the orthogonal linear polarizations simultaneously in the visible range. Both modulated transmitted phases of the orthogonal linear polarizations can almost span the whole 2π range by tailoring geometric sizes of the GaN nanobricks, while maintaining high values of transmission (almost all over 90%). At the wavelength of 530 nm, we designed and realized the beam splitter and the focusing lenses successfully. To further prove that our proposed method is suitable for arbitrary orthogonal linear polarization, we also designed a three-dimensional (3D) metalens that can simultaneously focus the X-, Y-, 45°, and 135° linear polarizations on spatially symmetric positions, which can be applied to the linear polarization measurement. Our work provides a possible method to achieve high-efficiency multifunctional optical devices in visible light by extending the modulating dimensions. Full article
(This article belongs to the Special Issue Optoelectronic Nanodevices)
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Open AccessArticle Self-Assembled Ag-Cu2O Nanocomposite Films at Air-Liquid Interfaces for Surface-Enhanced Raman Scattering and Electrochemical Detection of H2O2
Nanomaterials 2018, 8(5), 332; https://doi.org/10.3390/nano8050332
Received: 22 April 2018 / Revised: 8 May 2018 / Accepted: 8 May 2018 / Published: 15 May 2018
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Abstract
We employ a facile and novel route to synthesize multifunctional Ag-Cu2O nanocomposite films through the self-assembly of nanoparticles at an air-liquid interface. In the ethanol-water phase, AgNO3 and Cu(NO3)2 were reduced to Ag-Cu2O nanoparticles by
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We employ a facile and novel route to synthesize multifunctional Ag-Cu2O nanocomposite films through the self-assembly of nanoparticles at an air-liquid interface. In the ethanol-water phase, AgNO3 and Cu(NO3)2 were reduced to Ag-Cu2O nanoparticles by NaBH4 in the presence of cinnamic acid. The Ag-Cu2O nanoparticles were immediately trapped at the air-liquid interface to form two-dimensional nanocomposite films after the reduction reaction was finished. The morphology of the nanocomposite films could be controlled by the systematic regulation of experimental parameters. It was found that the prepared nanocomposite films serving as the substrates exhibited strong surface-enhanced Raman scattering (SERS) activity. 4-aminothiophenol (4-ATP) molecules were used as the test probes to examine the SERS sensitivity of the nanocomposite films. Moreover, the nanocomposite films synthesized by our method showed enhanced electrocatalytic activity towards hydrogen peroxide (H2O2) and therefore could be utilized to fabricate a non-enzymatic electrochemical H2O2 sensor. Full article
(This article belongs to the Special Issue Synthesis, Structure and Applications of 2D Nanomaterials)
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Open AccessArticle Simple, Low-Cost Fabrication of Highly Uniform and Reproducible SERS Substrates Composed of Ag–Pt Nanoparticles
Nanomaterials 2018, 8(5), 331; https://doi.org/10.3390/nano8050331
Received: 20 March 2018 / Revised: 2 May 2018 / Accepted: 10 May 2018 / Published: 15 May 2018
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Abstract
Ag–Pt nanoparticles, grafted on Ge wafer, were synthesized by the galvanic replacement reaction based on their different potentials. Detailed characterization through scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS) and X-ray photo-elelctron spectroscopy (XPS) proved that Ag–Pt nanoparticles are composed of large Ag
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Ag–Pt nanoparticles, grafted on Ge wafer, were synthesized by the galvanic replacement reaction based on their different potentials. Detailed characterization through scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS) and X-ray photo-elelctron spectroscopy (XPS) proved that Ag–Pt nanoparticles are composed of large Ag nanoparticles and many small Pt nanoparticles instead of an Ag–Pt alloy. When applied as surface-enhanced Raman scattering (SERS) substrates to detect Rhodamine 6G (1 × 10−8 M) or Crystal violet (1 × 10−7 M) aqueous solution in the line mapping mode, all of the obtained relative standard deviation (RSD) values of the major characteristic peak intensities, calculated from the SERS spectra of 100 serial spots, were less than 10%. The fabrication process of the SERS substrate has excellent uniformity and reproducibility and is simple, low-cost and time-saving, which will benefit studies on the platinum-catalyzed reaction mechanisms in situ and widen the practical application of SERS. Full article
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Open AccessArticle Enhanced Photocatalytic Activity toward Organic Pollutants Degradation and Mechanism Insight of Novel CQDs/Bi2O2CO3 Composite
Nanomaterials 2018, 8(5), 330; https://doi.org/10.3390/nano8050330
Received: 21 February 2018 / Revised: 10 May 2018 / Accepted: 10 May 2018 / Published: 15 May 2018
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Abstract
Novel carbon quantum dots (CQDs) modified with Bi2O2CO3 (CQDs/Bi2O2CO3) were prepared using a simple dynamic-adsorption precipitation method. X-ray diffractometry (XRD), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), and scanning electron
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Novel carbon quantum dots (CQDs) modified with Bi2O2CO3 (CQDs/Bi2O2CO3) were prepared using a simple dynamic-adsorption precipitation method. X-ray diffractometry (XRD), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), and scanning electron microscopy (SEM) were used to test the material composition, structure, and band structures of the as-prepared samples. Methylene blue (MB) and colorless phenol, as target organic pollutants, were used to evaluate the photocatalytic performance of the CQDs/Bi2O2CO3 hybrid materials under visible light irradiation. Experimental investigation shows that 2–5 nm CQDs were uniformly decorated on the surface of Bi2O2CO3; CQDs/Bi2O2CO3 possess an efficient photocatalytic performance, and the organic matter removal rate of methylene blue and phenol can reach up to 94.45% and 61.46% respectively, within 2 h. In addition, the degradation analysis of phenol by high performance liquid chromatography (HPLC) proved that there are no other impurities in the degradation process. Photoelectrochemical testing proved that the introduction of CQDs (electron acceptor) effectively suppresses the recombination of e-h+, and promotes charge transfer. Quenching experiments and electron spin resonance (ESR) suggested that ·OH, h+, and ·O2 were involved in the photocatalytic degradation process. These results suggested that the up-conversion function of CQDs could improve the electron transfer and light absorption ability of photocatalysts and ·O2 formation. Furthermore, the up-conversion function of CQDs would help maintain photocatalytic stability. Finally, the photocatalytic degradation mechanism was proposed according to the above experimental result. Full article
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Open AccessArticle Highly Efficient, Low-Cost, and Magnetically Recoverable FePt–Ag Nanocatalysts: Towards Green Reduction of Organic Dyes
Nanomaterials 2018, 8(5), 329; https://doi.org/10.3390/nano8050329
Received: 1 April 2018 / Revised: 11 May 2018 / Accepted: 11 May 2018 / Published: 14 May 2018
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Abstract
Nowadays, synthetic organic dyes and pigments discharged from numerous industries are causing unprecedentedly severe water environmental pollution, and conventional water treatment processes are hindered due to the corresponding sophisticated aromatic structures, hydrophilic nature, and high stability against light, temperature, etc. Herein, we report
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Nowadays, synthetic organic dyes and pigments discharged from numerous industries are causing unprecedentedly severe water environmental pollution, and conventional water treatment processes are hindered due to the corresponding sophisticated aromatic structures, hydrophilic nature, and high stability against light, temperature, etc. Herein, we report an efficient fabrication strategy to develop a new type of highly efficient, low-cost, and magnetically recoverable nanocatalyst, i.e., FePt–Ag nanocomposites, for the reduction of methyl orange (MO) and rhodamine B (RhB), by a facile seed deposition process. X-ray diffraction results elaborate that the as-synthesized FePt–Ag nanocomposites are pure disordered face-centered cubic phase. Transmission electron microscopy studies demonstrate that the amount of Ag seeds deposited onto the surfaces of FePt nanocrystals increases when increasing the additive amount of silver colloids. The linear correlation of the MO and RhB concentration versus reaction time catalyzed by FePt–Ag nanocatalysts is in line with pseudo-first-order kinetics. The reduction rate constants of MO and RhB increase with the increase of the amount of Ag seeds. FePt–Ag nanocomposites show good separation ability and reusability, and could be repeatedly applied for nearly complete reduction of MO and RhB for at least six successive cycles. Such cost-effective and recyclable nanocatalysts provide a new material family for use in environmental protection applications. Full article
(This article belongs to the Special Issue Alleviating Climate Change and Pollution with Nanomaterials)
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Open AccessReview Nanostructured Graphene: An Active Component in Optoelectronic Devices
Nanomaterials 2018, 8(5), 328; https://doi.org/10.3390/nano8050328
Received: 11 April 2018 / Revised: 11 May 2018 / Accepted: 12 May 2018 / Published: 14 May 2018
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Abstract
Nanostructured and chemically modified graphene-based nanomaterials possess intriguing properties for their incorporation as an active component in a wide spectrum of optoelectronic architectures. From a technological point of view, this aspect brings many new opportunities to the now well-known atomically thin carbon sheet,
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Nanostructured and chemically modified graphene-based nanomaterials possess intriguing properties for their incorporation as an active component in a wide spectrum of optoelectronic architectures. From a technological point of view, this aspect brings many new opportunities to the now well-known atomically thin carbon sheet, multiplying its application areas beyond transparent electrodes. This article gives an overview of fundamental concepts, theoretical backgrounds, design principles, technological implications, and recent advances in semiconductor devices that integrate nanostructured graphene materials into their active region. Starting from the unique electronic nature of graphene, a physical understanding of finite-size effects, non-idealities, and functionalizing mechanisms is established. This is followed by the conceptualization of hybridized films, addressing how the insertion of graphene can modulate or improve material properties. Importantly, it provides general guidelines for designing new materials and devices with specific characteristics. Next, a number of notable devices found in the literature are highlighted. It provides practical information on material preparation, device fabrication, and optimization for high-performance optoelectronics with a graphene hybrid channel. Finally, concluding remarks are made with the summary of the current status, scientific issues, and meaningful approaches to realizing next-generation technologies. Full article
(This article belongs to the Special Issue Synthesis, Structure and Applications of 2D Nanomaterials)
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Open AccessArticle An Antimicrobial Peptide-Loaded Gelatin/Chitosan Nanofibrous Membrane Fabricated by Sequential Layer-by-Layer Electrospinning and Electrospraying Techniques
Nanomaterials 2018, 8(5), 327; https://doi.org/10.3390/nano8050327
Received: 25 February 2018 / Revised: 22 April 2018 / Accepted: 4 May 2018 / Published: 14 May 2018
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Abstract
Guided bone regeneration (GBR) technique is widely used in the treatment of bone defects caused by peri-implantitis, periodontal disease, etc. However, the GBR membranes commonly used in clinical treatments currently have no antibacterial activity. Therefore, in this study, sequential layer-by-layer electrospinning and electrospraying
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Guided bone regeneration (GBR) technique is widely used in the treatment of bone defects caused by peri-implantitis, periodontal disease, etc. However, the GBR membranes commonly used in clinical treatments currently have no antibacterial activity. Therefore, in this study, sequential layer-by-layer electrospinning and electrospraying techniques were utilized to prepare a gelatin (Gln) and chitosan (CS) composite GBR membrane containing hydroxyapatite nanoparticles (nHAp) and antimicrobial peptide (Pac-525)-loaded PLGA microspheres (AMP@PLGA-MS), which was supposed to have osteogenic and antibacterial activities. The scanning electron microscope (SEM) observation showed that the morphology of the nanofibers and microspheres could be successfully produced. The diameters of the electrospun fibers with and without nHAp were 359 ± 174 nm and 409 ± 197 nm, respectively, and the mechanical properties of the membrane were measured according to the tensile stress-strain curve. Both the involvement of nHAp and the chemical crosslinking were able to enhance their tensile strength. In vitro cell culture of rat bone marrow mesenchymal stem cells (rBMSCs) indicated that the Gln/CS composite membrane had an ideal biocompatibility with good cell adhesion, spreading, and proliferation. In addition, the Gln/CS membrane containing nHAp could promote osteogenic differentiation of rBMSCs. Furthermore, according to the in vitro drug release assay and antibacterial experiments, the composite GBR membrane containing AMP@PLGA-MS exhibited a long-term sustained release of Pac-525, which had bactericidal activity within one week and antibacterial activity for up to one month against two kinds of bacteria, S. aureus and E. coli. Our results suggest that the antimicrobial peptide-loaded Gln/CS composite membrane (AMP@PLGA-MS@Gln/CS/nHAp) has a great promise in bone generation-related applications for the unique functions of guiding bone regeneration and inhibiting bacterial infection as well. Full article
(This article belongs to the Special Issue The Fabrication and Application of Nanofibers)
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Open AccessArticle Borylation of α,β-Unsaturated Acceptors by Chitosan Composite Film Supported Copper Nanoparticles
Nanomaterials 2018, 8(5), 326; https://doi.org/10.3390/nano8050326
Received: 30 April 2018 / Revised: 10 May 2018 / Accepted: 11 May 2018 / Published: 14 May 2018
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Abstract
We describe here the preparation of copper nanoparticles stabilized on a chitosan/poly (vinyl alcohol) composite film. This material could catalyze the borylation of α,β-unsaturated acceptors in aqueous media under mild conditions. The corresponding organoboron compounds as well as their converted β-hydroxyl products were
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We describe here the preparation of copper nanoparticles stabilized on a chitosan/poly (vinyl alcohol) composite film. This material could catalyze the borylation of α,β-unsaturated acceptors in aqueous media under mild conditions. The corresponding organoboron compounds as well as their converted β-hydroxyl products were all obtained in good to excellent yields. It is noteworthy that this catalyst of copper nanoparticles can be easily recycled eight times and remained catalytically reactive. This newly developed methodology provides an efficient and sustainable pathway for the synthesis of organoboron compounds and application of copper nanoparticles. Full article
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