Nanomaterials

12 pages, 3459 KiB

Open AccessArticle

Green Synthesis, Characterization and Application of Proanthocyanidins-Functionalized Gold Nanoparticles

by Linhai Biao, Shengnan Tan, Qinghuan Meng, Jing Gao, Xuewei Zhang, Zhiguo Liu and Yujie Fu

Nanomaterials 2018, 8(1), 53; https://doi.org/10.3390/nano8010053 - 21 Jan 2018

Cited by 105 | Viewed by 10160

Abstract

Green synthesis of gold nanoparticles using plant extracts is one of the more promising approaches for obtaining environmentally friendly nanomaterials for biological applications and environmental remediation. In this study, proanthocyanidins-functionalized gold nanoparticles were synthesized via a hydrothermal method. The obtained gold nanoparticles were [...] Read more.

Green synthesis of gold nanoparticles using plant extracts is one of the more promising approaches for obtaining environmentally friendly nanomaterials for biological applications and environmental remediation. In this study, proanthocyanidins-functionalized gold nanoparticles were synthesized via a hydrothermal method. The obtained gold nanoparticles were characterized by ultraviolet and visible spectrophotometry (UV-Vis), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and X-ray diffraction (XRD) measurements. UV-Vis and FTIR results indicated that the obtained products were mainly spherical in shape, and that the phenolic hydroxyl of proanthocyanidins had strong interactions with the gold surface. TEM and XRD determination revealed that the synthesized gold nanoparticles had a highly crystalline structure and good monodispersity. The application of proanthocyanidins-functionalized gold nanoparticles for the removal of dyes and heavy metal ions Ni²⁺, Cu²⁺, Cd²⁺ and Pb²⁺ in an aqueous solution was investigated. The primary results indicate that proanthocyanidins-functionalized gold nanoparticles had high removal rates for the heavy metal ions and dye, which implies that they have potential applications as a new kind of adsorbent for the removal of contaminants in aqueous solution. Full article

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17 pages, 7633 KiB

Open AccessArticle

Preparation of High Mechanical Performance Nano-Fe₃O₄/Wood Fiber Binderless Composite Boards for Electromagnetic Absorption via a Facile and Green Method

by Baokang Dang, Yipeng Chen, Hanwei Wang, Bo Chen, Chunde Jin and Qingfeng Sun

Nanomaterials 2018, 8(1), 52; https://doi.org/10.3390/nano8010052 - 21 Jan 2018

Cited by 33 | Viewed by 5633

Abstract

Fe₃O₄/wood fiber composites are prepared with a green mechanical method using only distilled water as a solvent without any chemical agents, and then a binderless composite board with high mechanical properties is obtained via a hot-press for electromagnetic (EM) [...] Read more.

Fe₃O₄/wood fiber composites are prepared with a green mechanical method using only distilled water as a solvent without any chemical agents, and then a binderless composite board with high mechanical properties is obtained via a hot-press for electromagnetic (EM) absorption. The fibers are connected by hydrogen bonds after being mechanically pretreated, and Fe₃O₄ nanoparticles (NPs) are attached to the fiber surface through physical adsorption. The composite board is bonded by an adhesive, which is provided by the reaction of fiber composition under high temperature and pressure. The Nano-Fe₃O₄/Fiber (NFF) binderless composite board shows remarkable microwave absorption properties and high mechanical strength. The optional reflection loss (RL) of the as-prepared binderless composite board is −31.90 dB. The bending strength of the NFF binderless composite board is 36.36 MPa with the addition of 6% nano-Fe₃O₄, the modulus of elasticity (MOE) is 6842.16 MPa, and the internal bond (IB) strength is 0.81 MPa. These results demonstrate that magnetic nanoparticles are deposited in binderless composite board by hot pressing, which is the easiest way to produce high mechanical strength and EM absorbers. Full article

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22 pages, 3698 KiB

Open AccessArticle

Fatty Acid Based Microemulsions to Combat Ophthalmia Neonatorum Caused by Neisseria gonorrhoeae and Staphylococcus aureus

by Ummara Butt, Amr ElShaer, Lori A. S. Snyder, Ali A. Al-Kinani, Adam Le Gresley and Raid G. Alany

Nanomaterials 2018, 8(1), 51; https://doi.org/10.3390/nano8010051 - 19 Jan 2018

Cited by 29 | Viewed by 5595

Abstract

The bacterial species Neisseria gonorrhoeae (N. gonorrhoeae) and Staphylococcus aureus (S. aureus) are amongst the main microorganisms that cause ophthalmia neonatorum. The current treatment involves the use of various antibiotics such as ciprofloxacin, cephalosporin, ceftriaxone and cefotaxime. However, this [...] Read more.

The bacterial species Neisseria gonorrhoeae (N. gonorrhoeae) and Staphylococcus aureus (S. aureus) are amongst the main microorganisms that cause ophthalmia neonatorum. The current treatment involves the use of various antibiotics such as ciprofloxacin, cephalosporin, ceftriaxone and cefotaxime. However, this treatment strategy is becoming more ineffective due to the antibiotic resistance in N. gonorrhoeae. The current study explores the potential use of fatty acid based microemulsions (ME) to prevent N. gonorrhoeae and S. aureus infections in new-borns’ eyes without harmful side effects such as corneal or conjunctiva irritation. Pseudo-ternary phase diagrams were constructed to evaluate microemulsion regions and six different α-linolenic acid based microemulsions were prepared. The prepared formulations were characterized for α-linolenic acid content, size, transparency, zeta potential, Polarized light Microscopy, antimicrobial activity and ex vivo ocular toxicity. The mean droplet size of the ME formulations was in the range of 190.4 to 350.5 nm and polydispersity index (PDI) values were in the range of 0.102 to 0.561. All formulations were found stable upon storage for at least 8 weeks. In addition, self-diffusion coefficients determined by nuclear magnetic resonance (NMR) reflected that the diffusability of water increased at higher than 30% w/w water, while that of fatty acids and surfactants was in reverse. The antimicrobial efficacy of microemulsions was determined against N. gonorrhoeae and S. aureus. It was concluded that all microemulsions have strong antimicrobial effects against N. gonorrhoeae and S. aureus. Finally, bovine corneal opacity permeability (BCOP) and hen’s egg chorioallantoic (HET-CAM) tests results showed that all microemulsion formulations were not strong ocular irritants. Full article

(This article belongs to the Special Issue Applications of Microemulsions in Biomedical Research)

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12 pages, 7097 KiB

Open AccessArticle

Micro-Spherical Sulfur/Graphene Oxide Composite via Spray Drying for High Performance Lithium Sulfur Batteries

by Yuan Tian, Zhenghao Sun, Yongguang Zhang, Xin Wang, Zhumabay Bakenov and Fuxing Yin

Nanomaterials 2018, 8(1), 50; https://doi.org/10.3390/nano8010050 - 18 Jan 2018

Cited by 42 | Viewed by 6359

Abstract

An efficient, industry-accepted spray drying method was used to synthesize micro-spherical sulfur/graphene oxide (S/GO) composites as cathode materials within lithium sulfur batteries. The as-designed wrapping of the sulfur-nanoparticles, with wrinkled GO composites, was characterized by scanning electron microscopy (SEM) and transmission electron microscopy [...] Read more.

An efficient, industry-accepted spray drying method was used to synthesize micro-spherical sulfur/graphene oxide (S/GO) composites as cathode materials within lithium sulfur batteries. The as-designed wrapping of the sulfur-nanoparticles, with wrinkled GO composites, was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The unique morphological design of this material enabled superior discharge capacity and cycling performance, demonstrating a high initial discharge capacity of 1400 mAh g⁻¹ at 0.1 C. The discharge capacity remained at 828 mAh g⁻¹ after 150 cycles. The superior electrochemical performance indicates that the S/GO composite improves electrical conductivity and alleviates the shuttle effect. This study represents the first time such a facile spray drying method has been adopted for lithium sulfur batteries and used in the fabrication of S/GO composites. Full article

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25 pages, 9667 KiB

Open AccessFeature PaperArticle

Filaments Production and Fused Deposition Modelling of ABS/Carbon Nanotubes Composites

by Sithiprumnea Dul, Luca Fambri and Alessandro Pegoretti

Nanomaterials 2018, 8(1), 49; https://doi.org/10.3390/nano8010049 - 18 Jan 2018

Cited by 142 | Viewed by 10611

Abstract

Composite acrylonitrile–butadiene–styrene (ABS)/carbon nanotubes (CNT) filaments at 1, 2, 4, 6 and 8 wt %, suitable for fused deposition modelling (FDM) were obtained by using a completely solvent-free process based on direct melt compounding and extrusion. The optimal CNT content in the filaments [...] Read more.

Composite acrylonitrile–butadiene–styrene (ABS)/carbon nanotubes (CNT) filaments at 1, 2, 4, 6 and 8 wt %, suitable for fused deposition modelling (FDM) were obtained by using a completely solvent-free process based on direct melt compounding and extrusion. The optimal CNT content in the filaments for FDM was found to be 6 wt %; for this composite, a detailed investigation of the thermal, mechanical and electrical properties was performed. Presence of CNT in ABS filaments and 3D-printed parts resulted in a significant enhancement of the tensile modulus and strength, accompanied by a reduction of the elongation at break. As documented by dynamic mechanical thermal analysis, the stiffening effect of CNTs in ABS is particularly pronounced at high temperatures. Besides, the presence of CNT in 3D-printed parts accounts for better creep and thermal dimensional stabilities of 3D-printed parts, accompanied by a reduction of the coefficient of thermal expansion). 3D-printed nanocomposite samples with 6 wt % of CNT exhibited a good electrical conductivity, even if lower than pristine composite filaments. Full article

(This article belongs to the Special Issue Polymer Nanocomposites)

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15 pages, 2520 KiB

Open AccessArticle

Zinc Tantalum Oxynitride (ZnTaO₂N) Photoanode Modified with Cobalt Phosphate Layers for the Photoelectrochemical Oxidation of Alkali Water

by Prabhakarn Arunachalam, Maged N. Shaddad, Mohamed A. Ghanem, Abdullah M. Al-Mayouf and Mark T. Weller

Nanomaterials 2018, 8(1), 48; https://doi.org/10.3390/nano8010048 - 18 Jan 2018

Cited by 16 | Viewed by 6048

Abstract

Photoanodes fabricated by the electrophoretic deposition of a thermally prepared zinc tantalum oxynitride (ZnTaO₂N) catalyst onto indium tin oxide (ITO) substrates show photoactivation for the oxygen evolution reaction (OER) in alkaline solutions. The photoactivity of the OER is further boosted by [...] Read more.

Photoanodes fabricated by the electrophoretic deposition of a thermally prepared zinc tantalum oxynitride (ZnTaO₂N) catalyst onto indium tin oxide (ITO) substrates show photoactivation for the oxygen evolution reaction (OER) in alkaline solutions. The photoactivity of the OER is further boosted by the photodeposition of cobalt phosphate (CoPi) layers onto the surface of the ZnTaO₂N photoanodes. Structural, morphological, and photoelectrochemical (PEC) properties of the modified ZnTaO₂N photoanodes are studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet visible (UV−Vis) diffuse reflectance spectroscopy, and electrochemical techniques. The presence of the CoPi layer significantly improved the PEC performance of water oxidation in an alkaline sulphate solution. The photocurrent-voltage behavior of the CoPi-modified ZnTaO₂N anodes was improved, with the influence being more prominent at lower oxidation potentials. A stable photocurrent density of about 2.3 mA·cm⁻² at 1.23 V vs. RHE was attained upon visible light illumination. Relative to the ZnTaO₂N photoanodes, an almost three-fold photocurrent increase was achieved at the CoPi/ZnTaO₂N photoelectrode. Perovskite-based oxynitrides are modified using an oxygen-evolution co-catalyst of CoPi, and provide a new dimension for enhancing the photoactivity of oxygen evolution in solar-assisted water-splitting reactions. Full article

(This article belongs to the Special Issue Synthesis and Applications of Nanomaterials for Photocatalysis and Electrocatalysis)

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14 pages, 2408 KiB

Open AccessArticle

Novel Hybrid Formulations Based on Thiourea Derivatives and Core@Shell Fe₃O₄@C₁₈ Nanostructures for the Development of Antifungal Strategies

by Carmen Limban, Alexandru Vasile Missir, Miron Teodor Caproiu, Alexandru Mihai Grumezescu, Mariana Carmen Chifiriuc, Coralia Bleotu, Luminita Marutescu, Marius Toma Papacocea and Diana Camelia Nuta

Nanomaterials 2018, 8(1), 47; https://doi.org/10.3390/nano8010047 - 17 Jan 2018

Cited by 17 | Viewed by 4983

Abstract

The continuously increasing global impact of fungal infections is requiring the rapid development of novel antifungal agents. Due to their multiple pharmacological activities, thiourea derivatives represent privileged candidates for shaping new drugs. We report here the preparation, physico-chemical characterization and bioevaluation of hybrid [...] Read more.

The continuously increasing global impact of fungal infections is requiring the rapid development of novel antifungal agents. Due to their multiple pharmacological activities, thiourea derivatives represent privileged candidates for shaping new drugs. We report here the preparation, physico-chemical characterization and bioevaluation of hybrid nanosystems based on new 2-((4-chlorophenoxy)methyl)-N-(substituted phenylcarbamo-thioyl)benzamides and Fe₃O₄@C₁₈ core@shell nanoparticles. The new benzamides were prepared by an efficient method, then their structure was confirmed by spectral studies and elemental analysis and they were further loaded on Fe₃O₄@C₁₈ nanostructures. Both the obtained benzamides and the resulting hybrid nanosystems were tested for their efficiency against planktonic and adherent fungal cells, as well as for their in vitro biocompatibility, using mesenchymal cells. The antibiofilm activity of the obtained benzamides was dependent on the position and nature of substituents, demonstrating that structure modulation could be a very useful approach to enhance their antimicrobial properties. The hybrid nanosystems have shown an increased efficiency in preventing the development of Candida albicans (C. albicans) biofilms and moreover, they exhibited a good biocompatibility, suggesting that Fe₃O₄@C₁₈core@shell nanoparticles could represent promising nanocarriers for antifungal substances, paving the way to the development of novel effective strategies with prophylactic and therapeutic value for fighting biofilm associated C. albicans infections. Full article

(This article belongs to the Special Issue Antibacterial Activity of Nanomaterials)

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12 pages, 7353 KiB

Open AccessArticle

Long-Term Mechanical Behavior of Nano Silica Sol Grouting

by Dongjiang Pan, Nong Zhang, Chenghao Zhang, Deyu Qian, Changliang Han and Sen Yang

Nanomaterials 2018, 8(1), 46; https://doi.org/10.3390/nano8010046 - 16 Jan 2018

Cited by 18 | Viewed by 5218

Abstract

The longevity of grouting has a significant effect on the safe and sustainable operation of many engineering projects. A 500-day experiment was carried out to study the long-term mechanical behavior of nano silica sol grouting. The nano silica sol was activated with different [...] Read more.

The longevity of grouting has a significant effect on the safe and sustainable operation of many engineering projects. A 500-day experiment was carried out to study the long-term mechanical behavior of nano silica sol grouting. The nano silica sol was activated with different proportions of a NaCl catalyst and cured under fluctuating temperature and humidity conditions. The mechanical parameters of the grout samples were tested using an electrohydraulic uniaxial compression tester and an improved Vicat instrument. Scanning electron microscope, X-ray diffraction, and ultrasonic velocity tests were carried out to analyze the strength change micro-mechanism. Tests showed that as the catalyst dosage in the grout mix is decreased, the curves on the graphs showing changes in the weight and geometric parameters of the samples over time could be divided into three stages, a shrinkage stage, a stable stage, and a second shrinkage stage. The catalyst improved the stability of the samples and reduced moisture loss. Temperature rise was also a driving force for moisture loss. Uniaxial compressive stress-strain curves for all of the samples were elastoplastic. The curves for uniaxial compression strength and secant modulus plotted against time could be divided into three stages. Sample brittleness increased with time and the brittleness index increased with higher catalyst dosages in the latter part of the curing time. Plastic strength-time curves exhibit allometric scaling. Curing conditions mainly affect the compactness, and then affect the strength. Full article

(This article belongs to the Special Issue Silicon-Based Nanomaterials: Technology and Applications)

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1 pages, 149 KiB

Open AccessCorrection

Correction: Dierking, Ingo and Al-Zangana, Shakhawan. Lyotropic Liquid Crystal Phases from Anisotropic Nanomaterials. Nanomaterials 2017, 7, 305

by Ingo Dierking and Shakhawan Al-Zangana

Nanomaterials 2018, 8(1), 45; https://doi.org/10.3390/nano8010045 - 15 Jan 2018

Cited by 1 | Viewed by 3833

Abstract

Due to an oversight during production, the authors wish to make the following correction to reference [65] of this paper [...] Full article

(This article belongs to the Special Issue Nanomaterials in Liquid Crystals)

15 pages, 4423 KiB

Open AccessFeature PaperArticle

Detection of ZrO₂ Nanoparticles in Lung Tissue Sections by Time-of-Flight Secondary Ion Mass Spectrometry and Ion Beam Microscopy

by Lothar Veith, Julia Böttner, Antje Vennemann, Daniel Breitenstein, Carsten Engelhard, Jan Meijer, Irina Estrela-Lopis, Martin Wiemann and Birgit Hagenhoff

Nanomaterials 2018, 8(1), 44; https://doi.org/10.3390/nano8010044 - 15 Jan 2018

Cited by 14 | Viewed by 6327

Abstract

The increasing use of nanoparticles (NP) in commercial products requires elaborated techniques to detect NP in the tissue of exposed organisms. However, due to the low amount of material, the detection and exact localization of NP within tissue sections is demanding. In this [...] Read more.

The increasing use of nanoparticles (NP) in commercial products requires elaborated techniques to detect NP in the tissue of exposed organisms. However, due to the low amount of material, the detection and exact localization of NP within tissue sections is demanding. In this respect, Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) and Ion Beam Microscopy (IBM) are promising techniques, because they both offer sub-micron lateral resolutions along with high sensitivities. Here, we compare the performance of the non-material-consumptive IBM and material-consumptive ToF-SIMS for the detection of ZrO₂ NP (primary size 9–10 nm) in rat lung tissue. Unfixed or methanol-fixed air-dried cryo-sections were subjected to IBM using proton beam scanning or to three-dimensional ToF-SIMS (3D ToF-SIMS) using either oxygen or argon gas cluster ion beams for complete sample sputtering. Some sample sites were analyzed first by IBM and subsequently by 3D ToF-SIMS, to compare results from exactly the same site. Both techniques revealed that ZrO₂ NP particles occurred mostly agglomerated in phagocytic cells with only small quantities being associated to the lung epithelium, with Zr, S, and P colocalized within the same biological structures. However, while IBM provided quantitative information on element distribution, 3D ToF-SIMS delivered a higher lateral resolution and a lower limit of detection under these conditions. We, therefore, conclude that 3D ToF-SIMS, although not yet a quantitative technique, is a highly valuable tool for the detection of NP in biological tissue. Full article

(This article belongs to the Special Issue Nanoparticles in Vivo and in Vitro Studies: A Collection of Parallel Approaches)

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11 pages, 3535 KiB

Open AccessReview

Recent Advances of Rare-Earth Ion Doped Luminescent Nanomaterials in Perovskite Solar Cells

by Yu Qiao, Shuhan Li, Wenhui Liu, Meiqing Ran, Haifei Lu and Yingping Yang

Nanomaterials 2018, 8(1), 43; https://doi.org/10.3390/nano8010043 - 15 Jan 2018

Cited by 58 | Viewed by 9368

Abstract

Organic-inorganic lead halide based perovskite solar cells have received broad interest due to their merits of low fabrication cost, a low temperature solution process, and high energy conversion efficiencies. Rare-earth (RE) ion doped nanomaterials can be used in perovskite solar cells to expand [...] Read more.

Organic-inorganic lead halide based perovskite solar cells have received broad interest due to their merits of low fabrication cost, a low temperature solution process, and high energy conversion efficiencies. Rare-earth (RE) ion doped nanomaterials can be used in perovskite solar cells to expand the range of absorption spectra and improve the stability due to its upconversion and downconversion effect. This article reviews recent progress in using RE-ion-doped nanomaterials in mesoporous electrodes, perovskite active layers, and as an external function layer of perovskite solar cells. Finally, we discuss the challenges facing the effective use of RE-ion-doped nanomaterials in perovskite solar cells and present some prospects for future research. Full article

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16 pages, 1416 KiB

Open AccessReview

Lipid-Based Nanoparticles as a Potential Delivery Approach in the Treatment of Rheumatoid Arthritis

by Shih-Yi Chuang, Chih-Hung Lin, Tse-Hung Huang and Jia-You Fang

Nanomaterials 2018, 8(1), 42; https://doi.org/10.3390/nano8010042 - 15 Jan 2018

Cited by 104 | Viewed by 13600

Abstract

Rheumatoid arthritis (RA), a chronic and joint-related autoimmune disease, results in immune dysfunction and destruction of joints and cartilages. Small molecules and biological therapies have been applied in a wide variety of inflammatory disorders, but their utility as a therapeutic agent is limited [...] Read more.

Rheumatoid arthritis (RA), a chronic and joint-related autoimmune disease, results in immune dysfunction and destruction of joints and cartilages. Small molecules and biological therapies have been applied in a wide variety of inflammatory disorders, but their utility as a therapeutic agent is limited by poor absorption, rapid metabolism, and serious side effects. To improve these limitations, nanoparticles, which are capable of encapsulating and protecting drugs from degradation before they reach the target site in vivo, may serve as drug delivery systems. The present research proposes a platform for different lipid nanoparticle approaches for RA therapy, taking advantage of the newly emerging field of lipid nanoparticles to develop a targeted theranostic system for application in the treatment of RA. This review aims to present the recent major application of lipid nanoparticles that provide a biocompatible and biodegradable delivery system to effectively improve RA targeting over free drugs via the presentation of tissue-specific targeting of ligand-controlled drug release by modulating nanoparticle composition. Full article

(This article belongs to the Special Issue Pharmaceutical Nanotechnology)

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12 pages, 16381 KiB

Open AccessArticle

Morphology-Controlled Synthesis of Hematite Nanocrystals and Their Optical, Magnetic and Electrochemical Performance

by Bangquan Li, Qian Sun, Hongsheng Fan, Ming Cheng, Aixian Shan, Yimin Cui and Rongming Wang

Nanomaterials 2018, 8(1), 41; https://doi.org/10.3390/nano8010041 - 15 Jan 2018

Cited by 12 | Viewed by 5722

Abstract

A series of α-Fe₂O₃ nanocrystals (NCs) with fascinating morphologies, such as hollow nanoolives, nanotubes, nanospindles, and nanoplates, were prepared through a simple template-free hydrothermal synthesis process. The results showed that the morphologies could be easily controlled by SO₄²⁻ [...] Read more.

A series of α-Fe₂O₃ nanocrystals (NCs) with fascinating morphologies, such as hollow nanoolives, nanotubes, nanospindles, and nanoplates, were prepared through a simple template-free hydrothermal synthesis process. The results showed that the morphologies could be easily controlled by SO₄²⁻ and H₂PO₄⁻. Physical property analysis showed that the α-Fe₂O₃ NCs exhibited shape- and size-dependent ferromagnetic and optical behaviors. The absorption band peak of the α-Fe₂O₃ NCs could be tuned from 320 to 610 nm. Furthermore, when applied as electrode material for supercapacitor, the hollow olive-structure exhibited the highest capacitance (285.9 F·g⁻¹) and an excellent long-term cycling stability (93% after 3000 cycles), indicating that it could serve as a candidate electrode material for a supercapacitor. Full article

(This article belongs to the Special Issue Nanomaterials Based Fuel Cells and Supercapacitors)

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12 pages, 8422 KiB

Open AccessArticle

Crystallization of TiO₂ Nanotubes by In Situ Heating TEM

by Alberto Casu, Andrea Lamberti, Stefano Stassi and Andrea Falqui

Nanomaterials 2018, 8(1), 40; https://doi.org/10.3390/nano8010040 - 14 Jan 2018

Cited by 24 | Viewed by 7312

Abstract

The thermally-induced crystallization of anodically grown TiO₂ amorphous nanotubes has been studied so far under ambient pressure conditions by techniques such as differential scanning calorimetry and in situ X-ray diffraction, then looking at the overall response of several thousands of nanotubes in [...] Read more.

The thermally-induced crystallization of anodically grown TiO₂ amorphous nanotubes has been studied so far under ambient pressure conditions by techniques such as differential scanning calorimetry and in situ X-ray diffraction, then looking at the overall response of several thousands of nanotubes in a carpet arrangement. Here we report a study of this phenomenon based on an in situ transmission electron microscopy approach that uses a twofold strategy. First, a group of some tens of TiO₂ amorphous nanotubes was heated looking at their electron diffraction pattern change versus temperature, in order to determine both the initial temperature of crystallization and the corresponding crystalline phases. Second, the experiment was repeated on groups of few nanotubes, imaging their structural evolution in the direct space by spherical aberration-corrected high resolution transmission electron microscopy. These studies showed that, differently from what happens under ambient pressure conditions, under the microscope’s high vacuum (p < 10⁻⁵ Pa) the crystallization of TiO₂ amorphous nanotubes starts from local small seeds of rutile and brookite, which then grow up with the increasing temperature. Besides, the crystallization started at different temperatures, namely 450 and 380 °C, when the in situ heating was performed irradiating the sample with electron beam energy of 120 or 300 keV, respectively. This difference is due to atomic knock-on effects induced by the electron beam with diverse energy. Full article

(This article belongs to the Special Issue ZnO and TiO₂ Based Nanostructures)

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14 pages, 750 KiB

Open AccessEditorial

Acknowledgement to Reviewers of Nanomaterials in 2017

by Nanomaterials Editorial Office

Nanomaterials 2018, 8(1), 39; https://doi.org/10.3390/nano8010039 - 13 Jan 2018

Viewed by 4296

Abstract

Peer review is an essential part in the publication process, ensuring that Nanomaterials maintains high quality standards for its published papers[...] Full article

15 pages, 3787 KiB

Open AccessArticle

Engineering Ru@Pt Core-Shell Catalysts for Enhanced Electrochemical Oxygen Reduction Mass Activity and Stability

by Ariel Jackson, Alaina Strickler, Drew Higgins and Thomas Francisco Jaramillo

Nanomaterials 2018, 8(1), 38; https://doi.org/10.3390/nano8010038 - 12 Jan 2018

Cited by 34 | Viewed by 8566

Abstract

Improving the performance of oxygen reduction reaction (ORR) electrocatalysts is essential for the commercial efficacy of many renewable energy technologies, including low temperature polymer electrolyte fuel cells (PEFCs). Herein, we report highly active and stable carbon-supported Ru@Pt core-shell nanoparticles (Ru@Pt/C) prepared by a [...] Read more.

Improving the performance of oxygen reduction reaction (ORR) electrocatalysts is essential for the commercial efficacy of many renewable energy technologies, including low temperature polymer electrolyte fuel cells (PEFCs). Herein, we report highly active and stable carbon-supported Ru@Pt core-shell nanoparticles (Ru@Pt/C) prepared by a wet chemical synthesis technique. Through rotating disc electrode testing, the Ru@Pt/C achieves an ORR Pt mass-based activity of 0.50 A mg_Pt⁻¹ at 0.9 V versus the reversible hydrogen electrode (RHE), which exceeds the activity of the state-of-the-art commercial Pt/C catalyst as well as the Department of Energy 2020 PEFC electrocatalyst activity targets for transportation applications. The impact of various synthetic parameters, including Pt to Ru ratios and catalyst pretreatments (i.e., annealing) are thoroughly explored. Pt-based mass activity of all prepared Ru@Pt/C catalysts was found to exceed 0.4 mg_Pt⁻¹ across the range of compositions investigated, with the maximum activity catalyst having a Ru:Pt ratio of 1:1. This optimized composition of Ru@Pt/C catalyst demonstrated remarkable stability after 30,000 accelerated durability cycles (0.6 to 1.0 V vs. RHE at 125 mV s⁻¹), maintaining 85% of its initial mass activity. Scanning transmission electron microscopy energy dispersive spectroscopy (STEM-EDS) analysis at various stages of electrochemical testing demonstrated that the Pt shell can provide sufficient protection against the dissolution of the otherwise unstable Ru core. Full article

(This article belongs to the Special Issue Nanomaterials Based Fuel Cells and Supercapacitors)

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20 pages, 3490 KiB

Open AccessArticle

Gentamicin Sulfate PEG-PLGA/PLGA-H Nanoparticles: Screening Design and Antimicrobial Effect Evaluation toward Clinic Bacterial Isolates

by Rossella Dorati, Antonella DeTrizio, Melissa Spalla, Roberta Migliavacca, Laura Pagani, Silvia Pisani, Enrica Chiesa, Bice Conti, Tiziana Modena and Ida Genta

Nanomaterials 2018, 8(1), 37; https://doi.org/10.3390/nano8010037 - 12 Jan 2018

Cited by 48 | Viewed by 8154

Abstract

Nanotechnology is a promising approach both for restoring or enhancing activity of old and conventional antimicrobial agents and for treating intracellular infections by providing intracellular targeting and sustained release of drug inside infected cells. The present paper introduces a formulation study of gentamicin [...] Read more.

Nanotechnology is a promising approach both for restoring or enhancing activity of old and conventional antimicrobial agents and for treating intracellular infections by providing intracellular targeting and sustained release of drug inside infected cells. The present paper introduces a formulation study of gentamicin loaded biodegradable nanoparticles (Nps). Solid-oil-in water technique was studied for gentamicin sulfate nanoencapsulation using uncapped Polylactide-co-glycolide (PLGA-H) and Polylactide-co-glycolide-co-Polyethylenglycol (PLGA-PEG) blends. Screening design was applied to optimize: drug payload, Nps size and size distribution, stability and resuspendability after freeze-drying. PLGA-PEG concentration resulted most significant factor influencing particles size and drug content (DC): 8 w/w% DC and 200 nm Nps were obtained. Stirring rate resulted most influencing factor for size distribution (PDI): 700 rpm permitted to obtain homogeneous Nps dispersion (PDI = 1). Further experimental parameters investigated, by 2³ screening design, were: polymer blend composition (PLGA-PEG and PLGA-H), Polyvinylalcohol (PVA) and methanol concentrations into aqueous phase. Drug content was increased to 10.5 w/w%. Nanoparticle lyophilization was studied adding cryoprotectants, polyvinypirrolidone K17 and K32, and sodiumcarboxymetylcellulose. Freeze-drying protocol was optimized by a mixture design. A freeze-dried Nps powder free resuspendable with stable Nps size and payload, was developed. The powder was tested on clinic bacterial isolates demonstrating that after encapsulation, gentamicin sulfate kept its activity. Full article

(This article belongs to the Special Issue Antibacterial Activity of Nanomaterials)

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12 pages, 8318 KiB

Open AccessArticle

Positron Spectroscopy of Nanodiamonds after Hydrogen Sorption

by Lyudmila Nikitina, Roman Laptev, Yuri Abzaev, Andrey Lider and Alexander Ivashutenko

Nanomaterials 2018, 8(1), 36; https://doi.org/10.3390/nano8010036 - 11 Jan 2018

Cited by 3 | Viewed by 4751

Abstract

The structure and defects of nanodiamonds influence the hydrogen sorption capacity. Positronium can be used as a sensor for detecting places with the most efficient capture of hydrogen atoms. Hydrogenation of carbon materials was performed from gas atmosphere. The concentration of hydrogen absorbed [...] Read more.

The structure and defects of nanodiamonds influence the hydrogen sorption capacity. Positronium can be used as a sensor for detecting places with the most efficient capture of hydrogen atoms. Hydrogenation of carbon materials was performed from gas atmosphere. The concentration of hydrogen absorbed by the sample depends on the temperature and pressure. The concentration 1.2 wt % is achieved at the temperature of 243 K and the pressure of 0.6 MPa. The hydrogen saturation of nanodiamonds changes the positron lifetime. Increase of sorption cycle numbers effects the positron lifetime, as well as the parameters of the Doppler broadening of annihilation line. The electron-positron annihilation being a sensitive method, it allows detecting the electron density fluctuation of the carbon material after hydrogen saturation. Full article

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14 pages, 5691 KiB

Open AccessArticle

Self-Assembled AgNP-Containing Nanocomposites Constructed by Electrospinning as Efficient Dye Photocatalyst Materials for Wastewater Treatment

by Yamei Liu, Caili Hou, Tifeng Jiao, Jingwen Song, Xu Zhang, Ruirui Xing, Jingxin Zhou, Lexin Zhang and Qiuming Peng

Nanomaterials 2018, 8(1), 35; https://doi.org/10.3390/nano8010035 - 10 Jan 2018

Cited by 151 | Viewed by 8401

Abstract

The design and self-assembly of graphene oxide (GO)-based composite membranes have attracted enormous attention due to their wide application in nanomaterial and environmental fields. In this work, we have successfully developed a strategy to fabricate new composite membranes based on poly(vinyl alcohol)/poly(acrylic acid)/carboxyl-functionalized [...] Read more.

The design and self-assembly of graphene oxide (GO)-based composite membranes have attracted enormous attention due to their wide application in nanomaterial and environmental fields. In this work, we have successfully developed a strategy to fabricate new composite membranes based on poly(vinyl alcohol)/poly(acrylic acid)/carboxyl-functionalized graphene oxide modified with silver nanoparticles (PVA/PAA/GO-COOH@AgNPs), which were prepared via thermal treatment and the electrospinning technique. Due to the strong π-π forces and strong electrostatic interactions of GO–COOH sheets, the prepared composite membranes and their lager surface areas were modified by scores of AgNPs, which demonstrated that a high-efficiency photocatalyst removed the organic dyes from the aqueous solutions. The prepared PVA/PAA/GO-COOH@AgNPs nanocomposite membranes showed a remarkable photocatalytic capacity in the catalytic degradation of the methylene blue dye solutions. Most importantly, the whole process was easy, mild, and eco-friendly. Additionally, the as-prepared membranes could be repeatedly used after the catalytic reaction. Full article

(This article belongs to the Special Issue The Fabrication and Application of Nanofibers)

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12 pages, 3828 KiB

Open AccessCommunication

Inihibition of Glycolysis by Using a Micro/Nano-Lipid Bromopyruvic Chitosan Carrier as a Promising Tool to Improve Treatment of Hepatocellular Carcinoma

by Nemany A. Hanafy, Luciana Dini, Cinzia Citti, Giuseppe Cannazza and Stefano Leporatti

Nanomaterials 2018, 8(1), 34; https://doi.org/10.3390/nano8010034 - 10 Jan 2018

Cited by 26 | Viewed by 5422

Abstract

Glucose consumption in many types of cancer cells, in particular hepatocellular carcinoma (HCC), was followed completely by over-expression of type II hexokinase (HKII). This evidence has been used in modern pharmacotherapy to discover therapeutic target against glycolysis in cancer cells. Bromopyruvate (BrPA) exhibits [...] Read more.

Glucose consumption in many types of cancer cells, in particular hepatocellular carcinoma (HCC), was followed completely by over-expression of type II hexokinase (HKII). This evidence has been used in modern pharmacotherapy to discover therapeutic target against glycolysis in cancer cells. Bromopyruvate (BrPA) exhibits antagonist property against HKII and can be used to inhibit glycolysis. However, the clinical application of BrPA is mostly combined with inhibition effect for healthy cells particularly erythrocytes. Our strategy is to encapsulate BrPA in a selected vehicle, without any leakage of BrPA out of vehicle in blood stream. This structure has been constructed from chitosan embedded into oleic acid layer and then coated by dual combination of folic acid (FA) and bovine serum albumin (BSA). With FA as specific ligand for cancer folate receptor and BSA that can be an easy binding for hepatocytes, they can raise the potential selection of carrier system. Full article

(This article belongs to the Special Issue Nanocolloids for Nanomedicine and Drug Delivery)

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13 pages, 6889 KiB

Open AccessArticle

Surface Decoration of ZnWO₄ Nanorods with Cu₂O Nanoparticles to Build Heterostructure with Enhanced Photocatalysis

by Lingyu Tian, Yulan Rui, Kelei Sun, Wenquan Cui and Weijia An

Nanomaterials 2018, 8(1), 33; https://doi.org/10.3390/nano8010033 - 9 Jan 2018

Cited by 42 | Viewed by 6262

Abstract

The surface of ZnWO₄ nanorods was decorated with Cu₂O nanoparticles (Cu₂O/ZnWO₄) prepared through a precipitation method. The Cu₂O nanoparticles were tightly deposited on the ZnWO₄ surface and had average diameters of 20 nm. [...] Read more.

The surface of ZnWO₄ nanorods was decorated with Cu₂O nanoparticles (Cu₂O/ZnWO₄) prepared through a precipitation method. The Cu₂O nanoparticles were tightly deposited on the ZnWO₄ surface and had average diameters of 20 nm. The nanoparticles not only promoted the absorption and utilization of visible light but also facilitated the separation of photogenerated charge carriers. This brought an improvement of the photocatalytic activity. The 5 wt % Cu₂O/ZnWO₄ photocatalyst displayed the highest degrade efficiency for methylene blue (MB) degradation under visible light, which was 7.8 and 2 times higher than pure ZnWO₄ and Cu₂O, respectively. Meanwhile, the Cu₂O/ZnWO₄ composite photocatalyst was able to go through phenol degradation under visible light. The results of photoluminescence (PL), photocurrent, and electrochemical impedance spectra (EIS) measurements were consistent and prove the rapid separation of charge, which originated from the match level structure and the close contact with the interface. The radical and hole trapping experiments were carried out to detect the main active substances in the photodegradation process. The holes and ·O₂⁻ radicals were predicted to dominate the photocatalytic process. Based on the characterization analysis and experiment results, a possible photocatalytic mechanism for enhancing photocatalytic activity was proposed. Full article

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11 pages, 2383 KiB

Open AccessArticle

Nanopatterning via Self-Assembly of a Lamellar-Forming Polystyrene-block-Poly(dimethylsiloxane) Diblock Copolymer on Topographical Substrates Fabricated by Nanoimprint Lithography

by Dipu Borah, Cian Cummins, Sozaraj Rasappa, Ramsankar Senthamaraikannan, Mathieu Salaun, Marc Zelsmann, George Liontos, Konstantinos Ntetsikas, Apostolos Avgeropoulos and Michael A. Morris

Nanomaterials 2018, 8(1), 32; https://doi.org/10.3390/nano8010032 - 9 Jan 2018

Cited by 19 | Viewed by 6079

Abstract

The self-assembly of a lamellar-forming polystyrene-block-poly(dimethylsiloxane) (PS-b-PDMS) diblock copolymer (DBCP) was studied herein for surface nanopatterning. The DBCP was synthesized by sequential living anionic polymerization of styrene and hexamethylcyclotrisiloxane (D₃). The number average molecular weight (M [...] Read more.

The self-assembly of a lamellar-forming polystyrene-block-poly(dimethylsiloxane) (PS-b-PDMS) diblock copolymer (DBCP) was studied herein for surface nanopatterning. The DBCP was synthesized by sequential living anionic polymerization of styrene and hexamethylcyclotrisiloxane (D₃). The number average molecular weight (M_n), polydispersity index (M_w/M_n) and PS volume fraction (φ_ps) of the DBCP were M_n^PS = 23.0 kg mol⁻¹, M_n^PDMS = 15.0 kg mol⁻¹, M_w/M_n = 1.06 and φ_ps = 0.6. Thin films of the DBCP were cast and solvent annealed on topographically patterned polyhedral oligomeric silsesquioxane (POSS) substrates. The lamellae repeat distance or pitch (λ_L) and the width of the PDMS features (d_L) are ~35 nm and ~17 nm, respectively, as determined by SEM. The chemistry of the POSS substrates was tuned, and the effects on the self-assembly of the DBCP noted. The PDMS nanopatterns were used as etching mask in order to transfer the DBCP pattern to underlying silicon substrate by a complex plasma etch process yielding sub-15 nm silicon features. Full article

(This article belongs to the Special Issue Self-Assembled Bio-Nanomaterials: Synthesis, Characterization, and Applications)

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16 pages, 5173 KiB

Open AccessArticle

Uniformly Dispersed and Re-Agglomerated Graphene Oxide-Based Cement Pastes: A Comparison of Rheological Properties, Mechanical Properties and Microstructure

by Wu-Jian Long, Hao-Dao Li, Chang-Le Fang and Feng Xing

Nanomaterials 2018, 8(1), 31; https://doi.org/10.3390/nano8010031 - 9 Jan 2018

Cited by 55 | Viewed by 6419

Abstract

The properties of graphene oxide (GO)-based cement paste can be significantly affected by the state of GO dispersion. In this study, the effects of uniformly dispersed and re-agglomerated GO on the rheological, mechanical properties and microstructure of cement paste were systematically investigated. Two [...] Read more.

The properties of graphene oxide (GO)-based cement paste can be significantly affected by the state of GO dispersion. In this study, the effects of uniformly dispersed and re-agglomerated GO on the rheological, mechanical properties and microstructure of cement paste were systematically investigated. Two distinct dispersion states can be achieved by altering the mixing sequence: Polycarboxylate-ether (PCE) mixed with GO-cement or cement mixed with GO-PCE. The experimental results showed that the yield stress and plastic viscosity increased with the uniformly dispersed GO when compared to those of re-agglomerated GO cement paste. Moreover, the 3-day compressive and flexural strengths of uniformly dispersed GO paste were 8% and 27%, respectively, higher than those of re-agglomerated GO pastes. The results of X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy analyses demonstrated that uniformly dispersed GO more effectively promotes the formation of hydration products in hardened cement paste. Furthermore, a porosity analysis using mercury intrusion porosimetry revealed that the homogeneous dispersion of GO can better inhibit the formation of large-size pores and optimize the pore size distribution at 3 and 7 days than the re-agglomerated GO. Full article

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9 pages, 1290 KiB

Open AccessFeature PaperArticle

TiO₂ Films Modified with Au Nanoclusters as Self-Cleaning Surfaces under Visible Light

by Ting-Wei Liao, Sammy W. Verbruggen, Nathalie Claes, Anupam Yadav, Didier Grandjean, Sara Bals and Peter Lievens

Nanomaterials 2018, 8(1), 30; https://doi.org/10.3390/nano8010030 - 8 Jan 2018

Cited by 31 | Viewed by 6317

Abstract

In this study, we applied cluster beam deposition (CBD) as a new approach for fabricating efficient plasmon-based photocatalytic materials. Au nanoclusters (AuNCs) produced in the gas phase were deposited on TiO₂ P25-coated silicon wafers with coverage ranging from 2 to 8 atomic [...] Read more.

In this study, we applied cluster beam deposition (CBD) as a new approach for fabricating efficient plasmon-based photocatalytic materials. Au nanoclusters (AuNCs) produced in the gas phase were deposited on TiO₂ P25-coated silicon wafers with coverage ranging from 2 to 8 atomic monolayer (ML) equivalents. Scanning Electron Microscopy (SEM) images of the AuNCs modified TiO₂ P25 films show that the surface is uniformly covered by the AuNCs that remain isolated at low coverage (2 ML, 4 ML) and aggregate at higher coverage (8 ML). A clear relationship between AuNCs coverage and photocatalytic activity towards stearic acid photo-oxidation was measured, both under ultraviolet and green light illumination. TiO₂ P25 covered with 4 ML AuNCs showed the best stearic acid photo-oxidation performance under green light illumination (Formal Quantum Efficiency 1.6 × 10⁻⁶ over a period of 93 h). These results demonstrate the large potential of gas-phase AuNCs beam deposition technology for the fabrication of visible light active plasmonic photocatalysts. Full article

(This article belongs to the Special Issue Preparation and Application of Hybrid Nanomaterials)

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18 pages, 8202 KiB

Open AccessArticle

A Tensile Constitutive Relationship and a Finite Element Model of Electrospun Nanofibrous Mats

by Yunlei Yin, Zhongxiang Pan and Jie Xiong

Nanomaterials 2018, 8(1), 29; https://doi.org/10.3390/nano8010029 - 8 Jan 2018

Cited by 21 | Viewed by 5708

Abstract

It is difficult to establish a numerical model for a certain structure of electrospun nanofibrous mats, due to their high porosity and non-linear characteristics, that can fully consider these characteristics and describe their mechanical behaviors. In this paper, an analytical method of meso-mechanics [...] Read more.

It is difficult to establish a numerical model for a certain structure of electrospun nanofibrous mats, due to their high porosity and non-linear characteristics, that can fully consider these characteristics and describe their mechanical behaviors. In this paper, an analytical method of meso-mechanics was adopted to establish the tensile constitutive relationship between a single fiber and mats from fiber-web microstructures. Meanwhile, a macroscopic finite element model was developed and verified through uniaxial tensile stress-strain experimental data of silk fibroin (SF)/polycaprolactone (PCL) nanofibrous mats. The compared results show that the constitutive relation and finite element model could satisfactorily express elastic-plastic tensile mechanical behaviors of the polymer. This model helps regulate the microstructure of nanofibrous mats to meet the mechanical requirements in engineering applications. Full article

(This article belongs to the Special Issue Nano-scale Mechanics of Biological Materials)

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20 pages, 4273 KiB

Open AccessArticle

UV-Vis-Induced Degradation of Phenol over Magnetic Photocatalysts Modified with Pt, Pd, Cu and Au Nanoparticles

by Izabela Wysocka, Ewa Kowalska, Konrad Trzciński, Marcin Łapiński, Grzegorz Nowaczyk and Anna Zielińska-Jurek

Nanomaterials 2018, 8(1), 28; https://doi.org/10.3390/nano8010028 - 7 Jan 2018

Cited by 70 | Viewed by 8414

Abstract

The combination of TiO₂ photocatalyst and magnetic oxide nanoparticles enhances the separation and recoverable properties of nanosized TiO₂ photocatalyst. Metal-modified (Me = Pd, Au, Pt, Cu) TiO₂/SiO₂@Fe₃O₄ nanocomposites were prepared by an ultrasonic-assisted sol-gel [...] Read more.

The combination of TiO₂ photocatalyst and magnetic oxide nanoparticles enhances the separation and recoverable properties of nanosized TiO₂ photocatalyst. Metal-modified (Me = Pd, Au, Pt, Cu) TiO₂/SiO₂@Fe₃O₄ nanocomposites were prepared by an ultrasonic-assisted sol-gel method. All prepared samples were characterized by X-ray powder diffraction (XRD) analysis, Brunauer-Emmett-Teller (BET) method, X-ray photoelectron spectroscopy (XPS), scanning transmission electron microscopy (STEM), Mott-Schottky analysis and photoluminescence spectroscopy (PL). Phenol oxidation pathways of magnetic photocatalysts modified with Pt, Pd, Cu and Au nanoparticles proceeded by generation of reactive oxygen species, which oxidized phenol to benzoquinone, hydroquinone and catechol. Benzoquinone and maleic acid were products, which were determined in the hydroquinone oxidation pathway. The highest mineralization rate was observed for Pd-TiO₂/SiO₂@Fe₃O₄ and Cu-TiO₂/SiO₂@Fe₃O₄ photocatalysts, which produced the highest concentration of catechol during photocatalytic reaction. For Pt-TiO₂/SiO₂@Fe₃O₄ nanocomposite, a lack of catechol after 60 min of irradiation resulted in low mineralization rate (CO₂ formation). It is proposed that the enhanced photocatalytic activity of palladium and copper-modified photocatalysts is related to an increase in the amount of adsorption sites and efficient charge carrier separation, whereas the keto-enol tautomeric equilibrium retards the rate of phenol photomineralization on Au-TiO₂/SiO₂@Fe₃O₄. The magnetization hysteresis loop indicated that the obtained hybrid photocatalyst showed magnetic properties and therefore could be easily separated after treatment process. Full article

(This article belongs to the Special Issue Noble Metal Nanoparticles in Catalysis)

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20 pages, 5686 KiB

Open AccessArticle

Effects of Reorientation of Graphene Platelets (GPLs) on Young’s Modulus of Polymer Composites under Bi-Axial Stretching

by Chuang Feng, Yu Wang and Jie Yang

Nanomaterials 2018, 8(1), 27; https://doi.org/10.3390/nano8010027 - 7 Jan 2018

Cited by 34 | Viewed by 4776

Abstract

Effects of bi-axial stretching induced reorientation of graphene platelets (GPLs) on the Young’s modulus of GPL/polymer composites is studied by Mori-Tanaka micromechanics model. The dispersion state of the GPLs in polymer matrix is captured by an orientation distribution function (ODF), in which two [...] Read more.

Effects of bi-axial stretching induced reorientation of graphene platelets (GPLs) on the Young’s modulus of GPL/polymer composites is studied by Mori-Tanaka micromechanics model. The dispersion state of the GPLs in polymer matrix is captured by an orientation distribution function (ODF), in which two Euler angles are used to identify the orientation of the GPLs. Compared to uni-axial stretching, the increase of the stretching strain in the second direction enhances the re-alignment of GPL fillers in this direction while it deteriorates the re-alignment of the fillers in the other two directions. Comprehensive parametric study on the effects of the out-of-plane Young’s modulus, stretching strain, strain ratio, Poisson’s ratio and weight fraction and GPL dimension on the effective Young’s moduli of the composites in the three directions are conducted. It is found that the out-of-plane Young’s modulus has limited effects on the overall Young’s modulus of the composites. The second stretching enhances the Young’s modulus in this direction while it decreases the Young’s modulus in the other two directions. The results demonstrate the increase of Poisson’s ratio is favorable in increasing the Young’s modulus of the composites. GPLs with larger diameter-to-thickness ratio have better reinforcing effect on the Young’s modulus of GPL/polymer nanocomposites. Full article

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13 pages, 3219 KiB

Open AccessArticle

UV-Assisted Photochemical Synthesis of Reduced Graphene Oxide/ZnO Nanowires Composite for Photoresponse Enhancement in UV Photodetectors

by Changsong Chen, Peng Zhou, Na Wang, Yang Ma and Haisheng San

Nanomaterials 2018, 8(1), 26; https://doi.org/10.3390/nano8010026 - 5 Jan 2018

Cited by 36 | Viewed by 7168

Abstract

The weak photon absorption and high recombination rate of electron-hole pairs in disordered zinc oxide nanowires (ZNWs) limit its application in UV photodetection. This limitation can be overcome by introducing graphene sheets to the ZNWs. Herein we report a high-performance photodetector based on [...] Read more.

The weak photon absorption and high recombination rate of electron-hole pairs in disordered zinc oxide nanowires (ZNWs) limit its application in UV photodetection. This limitation can be overcome by introducing graphene sheets to the ZNWs. Herein we report a high-performance photodetector based on one-dimensional (1D) wide band-gap semiconductor disordered ZNWs composited with reduced graphene oxide (RGO) for ultraviolet (UV) photoresponse enhancement. The RGO/ZNWs composites have been successfully synthetized through UV-assisted photochemical reduction of GO in ZNWs suspension. The material characterizations in morphology, Raman scattering, and Ultraviolet-visible light absorption verified the formation of graphene sheets attached in ZNWs network and the enhancement of UV absorption due to the introduction of graphene. In comparison with photodetectors based on pure ZNWs, the photodetectors based on RGO/ZNWs composite exhibit enhanced photoresponse with photocurrent density of 5.87 mA·cm⁻², on/off current ratio of 3.01 × 10⁴, and responsivity of 1.83 A·W⁻¹ when a UV irradiation of 3.26 mW·cm⁻² and 1.0 V bias were used. Theory analysis is also presented to get insight into the inherent mechanisms of separation and transportation of photo-excited carriers in RGO/ZNWs composite. Full article

(This article belongs to the Special Issue Nanomaterials for Sensing Applications)

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18 pages, 2697 KiB

Open AccessArticle

Comparative Evaluation of U.S. Brand and Generic Intravenous Sodium Ferric Gluconate Complex in Sucrose Injection: Physicochemical Characterization

by Dajun Sun, Rodney Rouse, Vikram Patel, Yong Wu, Jiwen Zheng, Alokita Karmakar, Anil K. Patri, Priyanka Chitranshi, David Keire, Jia Ma and Wenlei Jiang

Nanomaterials 2018, 8(1), 25; https://doi.org/10.3390/nano8010025 - 5 Jan 2018

Cited by 15 | Viewed by 9731

Abstract

The objective of this study was to evaluate physicochemical equivalence between brand (i.e., Ferrlecit) and generic sodium ferric gluconate (SFG) in sucrose injection by conducting a series of comparative in vitro characterizations using advanced analytical techniques. The elemental iron and carbon content, thermal [...] Read more.

The objective of this study was to evaluate physicochemical equivalence between brand (i.e., Ferrlecit) and generic sodium ferric gluconate (SFG) in sucrose injection by conducting a series of comparative in vitro characterizations using advanced analytical techniques. The elemental iron and carbon content, thermal properties, viscosity, particle size, zeta potential, sedimentation coefficient, and molecular weight were determined. There was no noticeable difference between brand and generic SFG in sucrose injection for the above physical parameters evaluated, except for the sedimentation coefficient determined by sedimentation velocity analytical ultracentrifugation (SV-AUC) and molecular weight by asymmetric field flow fractionation-multi-angle light scattering (AFFF-MALS). In addition, brand and generic SFG complex products showed comparable molecular weight distributions when determined by gel permeation chromatography (GPC). The observed minor differences between brand and generic SFG, such as sedimentation coefficient, do not impact their biological activities in separate studies of in vitro cellular uptake and rat biodistribution. Coupled with the ongoing clinical study comparing the labile iron level in healthy volunteers, the FDA-funded post-market studies intended to illustrate comprehensive surveillance efforts ensuring safety and efficacy profiles of generic SFG complex in sucrose injection, and also to shed new light on the approval standards on generic parenteral iron colloidal products. Full article

(This article belongs to the Special Issue Pharmaceutical Nanotechnology)

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19 pages, 4232 KiB

Open AccessArticle

Thermally Stimulated Currents in Nanocrystalline Titania

by Mara Bruzzi, Riccardo Mori, Andrea Baldi, Ennio Antonio Carnevale, Alessandro Cavallaro and Monica Scaringella

Nanomaterials 2018, 8(1), 13; https://doi.org/10.3390/nano8010013 - 5 Jan 2018

Cited by 7 | Viewed by 5352

Abstract

A thorough study on the distribution of defect-related active energy levels has been performed on nanocrystalline TiO₂. Films have been deposited on thick-alumina printed circuit boards equipped with electrical contacts, heater and temperature sensors, to carry out a detailed thermally stimulated [...] Read more.

A thorough study on the distribution of defect-related active energy levels has been performed on nanocrystalline TiO₂. Films have been deposited on thick-alumina printed circuit boards equipped with electrical contacts, heater and temperature sensors, to carry out a detailed thermally stimulated currents analysis on a wide temperature range (5–630 K), in view to evidence contributions from shallow to deep energy levels within the gap. Data have been processed by numerically modelling electrical transport. The model considers both free and hopping contribution to conduction, a density of states characterized by an exponential tail of localized states below the conduction band and the convolution of standard Thermally Stimulated Currents (TSC) emissions with gaussian distributions to take into account the variability in energy due to local perturbations in the highly disordered network. Results show that in the low temperature range, up to 200 K, hopping within the exponential band tail represents the main contribution to electrical conduction. Above room temperature, electrical conduction is dominated by free carriers contribution and by emissions from deep energy levels, with a defect density ranging within 10¹⁴–10¹⁸ cm⁻³, associated with physio- and chemi-sorbed water vapour, OH groups and to oxygen vacancies. Full article

(This article belongs to the Special Issue ZnO and TiO₂ Based Nanostructures)

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