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Nanomaterials
Volume 7
Issue 2
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Nanomaterials, Volume 7, Issue 2 (February 2017) – 27 articles

Cover Story (view full-size image): Metal organic nanomaterials are promising constituents in the fabrication of efficient, and low-cost photoelectrodes for solar fuels. In this work, we synthesise a metal organic cluster complex {Ni4O4} and pair it with silicon nanowire (SiNW) electrodes to enhance the reductive photocurrent response for hydrogen generation. We show an enhanced photocurrent response of 60% when compared to bare SiNWs and verify our system as an efficient and stable photocathode for water splitting. View this paper.
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1926 KiB  
Review
Evaluating Adverse Effects of Inhaled Nanoparticles by Realistic In Vitro Technology
by Marianne Geiser, Natalie Jeannet, Martin Fierz and Heinz Burtscher
Nanomaterials 2017, 7(2), 49; https://doi.org/10.3390/nano7020049 - 22 Feb 2017
Cited by 50 | Viewed by 6810
Abstract
The number of daily products containing nanoparticles (NP) is rapidly increasing. NP in powders, dispersions, or sprays are a yet unknown risk for incidental exposure, especially at workplaces during NP production and processing, and for consumers of any health status and age using [...] Read more.
The number of daily products containing nanoparticles (NP) is rapidly increasing. NP in powders, dispersions, or sprays are a yet unknown risk for incidental exposure, especially at workplaces during NP production and processing, and for consumers of any health status and age using NP containing sprays. We developed the nano aerosol chamber for in vitro toxicity (NACIVT), a portable instrument for realistic safety testing of inhaled NP in vitro and evaluated effects of silver (Ag) and carbon (C) NP—which belong to the most widely used nanomaterials—on normal and compromised airway epithelia. We review the development, physical performance, and suitability of NACIVT for short and long-term exposures with air-liquid interface (ALI) cell cultures in regard to the prerequisites of a realistic in vitro test system for inhalation toxicology and in comparison to other commercially available, well characterized systems. We also review doses applied to cell cultures in vitro and acknowledge that a single exposure to realistic doses of spark generated 20-nm Ag- or CNP results in small, similar cellular responses to both NP types and that cytokine release generally increased with increasing NP dose. Full article
(This article belongs to the Special Issue Cytotoxicity of Nanoparticles)
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<p>Nano Aerosol Chamber for In Vitro Toxicity (NACIVT). (<b>A</b>) Picture of chamber with dedicated laptop and LabVIEW software; (<b>B</b>) schematic section showing and describing the main parts of the chamber.</p> Full article ">Figure 2
<p>Particle delivery by electrostatic precipitation. Schematic section of an aerosol delivery tube, its Transwell<sup>®</sup> insert and the insert-holder plate, demonstrating the aerosol flow and particle deposition on the cell culture. In this schematic, particles are previously charged by a unipolar diffusion charger.</p> Full article ">Figure 3
<p>Experimental setup for deposition efficiency measurements with fluorescent polystyrene latex particles (PSL) [<a href="#B38-nanomaterials-07-00049" class="html-bibr">38</a>]. (<b>A</b>) Nebulizer and (<b>B</b>) silica gel dryer for aerosol generation; (<b>C</b>,<b>D</b>) Instruments for SMPS—particle sizing; (<b>E</b>) NACIVT chamber for cell exposure at air-liquid interface; and (<b>F</b>) chamber-controlling laptop with a LabVIEW based program (National Instruments Switzerland GmbH, Ennetbaden, Switzerland).</p> Full article ">Figure 4
<p>Morphology of in vitro differentiated human bronchial epithelia. (<b>A</b>) Light microscopic image exhibiting pseudostratified epithelium with basal (BC), ciliated (CC), and secretory (SC) cells; (<b>B</b>) transmission; and (<b>C</b>) scanning electron micrographs showing apical cell differentiations (cilia and microvilli) and junctional complexes (arrow heads in <b>B</b>).</p> Full article ">
3878 KiB  
Review
Antimicrobial Polymers in the Nano-World
by Marta Álvarez-Paino, Alexandra Muñoz-Bonilla and Marta Fernández-García
Nanomaterials 2017, 7(2), 48; https://doi.org/10.3390/nano7020048 - 22 Feb 2017
Cited by 132 | Viewed by 16387
Abstract
Infections are one of the main concerns of our era due to antibiotic-resistant infections and the increasing costs in the health-care sector. Within this context, antimicrobial polymers present a great alternative to combat these problems since their mechanisms of action differ from those [...] Read more.
Infections are one of the main concerns of our era due to antibiotic-resistant infections and the increasing costs in the health-care sector. Within this context, antimicrobial polymers present a great alternative to combat these problems since their mechanisms of action differ from those of antibiotics. Therefore, the microorganisms’ resistance to these polymeric materials is avoided. Antimicrobial polymers are not only applied in the health-care sector, they are also used in many other areas. This review presents different strategies that combine nanoscience and nanotechnology in the polymer world to combat contaminations from bacteria, fungi or algae. It focuses on the most relevant areas of application of these materials, viz. health, food, agriculture, and textiles. Full article
(This article belongs to the Special Issue Antimicrobial Nanomaterials and Nanotechnology)
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<p>Schematic structure of thermo-responsive and biodegradable hydrogel and the process of drug loading and release from thermo- and reduction-responsive hydrogel after morphological transformation by glutathione.</p> Full article ">Figure 2
<p>Histopathological microscopic images of kidney tissues of AJ-646 mice euthanized 5 days after intraperitoneal administration: (<b>a</b>) untreated control group; (<b>b</b>) mice group treated with 15 mg/g body weight with free gentamicin: Minimal to mild lymphocytic inflammation (<b>green</b> arrow) associated with mineralized deposits (<b>orange</b> arrows); (<b>c</b>) mice group treated with 15 mg/g body weight with core-shell nanostructure: typically unremarkable to rare small peri-glomerular aggregates of mononuclear cells (arrow). The tissues were hematoxylin and eosin stained. Scale bar of 50 μm. Reproduced from [<a href="#B50-nanomaterials-07-00048" class="html-bibr">50</a>]. Copyright Dove Medical Press Ltd., 2009.</p> Full article ">Figure 3
<p>Charts showing antibacterial activity of samples eluted from bone cement with different preparations (antibiotic preparations added to bone cement: powder vancomycin, the inert filler xylitol/powder vancomycin, liquid vancomycin), as determined by the agar-disk diffusion bioassay. Bone cement without antibiotics served as control. The data are presented in terms of growing inhibition of methicillin-resistant <span class="html-italic">S. aureus</span> bacteria. The growth was visually compared with standard samples containing different concentrations of vancomycin. Reproduced from reference [<a href="#B105-nanomaterials-07-00048" class="html-bibr">105</a>]. Copyright the British Editorial Society of Bone &amp; Joint Surgery, 2014.</p> Full article ">Figure 4
<p><b>Upper figures</b>: Electrospun polyacrylonitrile (PAN)-Por<sup>(+)</sup> scaffold and scanning electron microscopy images. <b>Lower figures</b>: Photodynamic inactivation studies employing PAN-Por<sup>(+)</sup>. (<b>A</b>) Gram-positive species: methicillin-susceptible <span class="html-italic">S. aureus</span> ATCC-2913 and the vancomycin-resistant <span class="html-italic">E. faecium</span> ATCC-2320 strain; (<b>B</b>) Gram-negative species: <span class="html-italic">E. coli</span> BL21-(Dε3)pLysS, <span class="html-italic">K. pneumoniae</span> ATCC-2146, and <span class="html-italic">A. baumannii</span> ATCC-19606. For both panels, it is displayed the material-free (cells-only) dark control set to 100% (<b>black</b>), as well as the dark control of PAN-Por<sup>(+)</sup> (<b>maroon</b>) and the illuminated PAN-Por<sup>(+)</sup> (<b>red</b>) studies, both as survival rates relative to the material-free (cells-only) dark control. For all bacteria the illumination conditions were as follows: 30 min, 400–700 nm, 65 ± 5 mW/cm<sup>2</sup> (total fluency of 118 J/cm<sup>2</sup>). Reproduced from [<a href="#B220-nanomaterials-07-00048" class="html-bibr">220</a>].</p> Full article ">Figure 5
<p>Polymeric surfaces with biocidal activity.</p> Full article ">Figure 6
<p>Schematic representation of antibiofouling surfaces. (<b>a</b>) Adhesion-resistant surfaces; (<b>b</b>) Non-toxic biocide releasing matrices.</p> Full article ">Figure 7
<p>Application of nanotechnology in pesticide delivery.</p> Full article ">Figure 8
<p>Schematic illustration for the assembly process of a photo-sensitive polymer-agrochemical conjugate and its photocleavage process under light irradiation and subsequent cargo release.</p> Full article ">
2907 KiB  
Article
The Influence of New Hydrophobic Silica Nanoparticles on the Surface Properties of the Films Obtained from Bilayer Hybrids
by Cristian Petcu, Violeta Purcar, Cătălin-Ilie Spătaru, Elvira Alexandrescu, Raluca Şomoghi, Bogdan Trică, Sabina Georgiana Niţu, Denis Mihaela Panaitescu, Dan Donescu and Maria-Luiza Jecu
Nanomaterials 2017, 7(2), 47; https://doi.org/10.3390/nano7020047 - 20 Feb 2017
Cited by 46 | Viewed by 7409
Abstract
Ultra-hydrophobic bilayer coatings on a glass surface were fabricated by sol–gel process using hexadecyltrimethoxysilane (C16TMS) and tetramethoxysilane (TMOS) (1:4 molar ratio) as precursors. After coating, silica nanoparticles (SiO2 NPs) functionalized with different mono-alkoxy derivatives (methoxytrimethylsilane, TMeMS; ethoxydimethylvinylsilane, DMeVES; ethoxydimethylphenylsilane, DMePhES; [...] Read more.
Ultra-hydrophobic bilayer coatings on a glass surface were fabricated by sol–gel process using hexadecyltrimethoxysilane (C16TMS) and tetramethoxysilane (TMOS) (1:4 molar ratio) as precursors. After coating, silica nanoparticles (SiO2 NPs) functionalized with different mono-alkoxy derivatives (methoxytrimethylsilane, TMeMS; ethoxydimethylvinylsilane, DMeVES; ethoxydimethylphenylsilane, DMePhES; and methoxydimethyloctylsilane, DMeC8MS) were added, assuring the microscale roughness on the glass surface. Influences of the functionalized SiO2 NPs and surface morphology on the hydrophobicity of the hybrid films were discussed. The successful functionalization of SiO2 NPs with hydrophobic alkyl groups were confirmed by Fourier transform infrared spectroscopy (FTIR). The thermal stability of hydrophobic SiO2 NPs showed that the degradation of the alkyl groups takes place in the 200–400 °C range. Bilayer coating with C16TMS/TMOS and SiO2 NPs modified with alkoxysilane substituted with C8 alkyl chain (SiO2 NP-C8) has micro/nano structure. Hydrophobicity of functionalized SiO2 NPs-C8 and its higher degree of nanometer-scale roughness gave rise to ultra-hydrophobicity performance for bilayer coating C16TMS/TMOS + SiO2 NPs-C8 (145°), compared to other similar hybrid structures. Our synthesis method for the functionalization of SiO2 NPs is useful for the modification of surface polarity and roughness. Full article
(This article belongs to the Special Issue Nanocomposite Coatings)
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<p>The average particle size of pristine silica nanoparticles (SiO<sub>2</sub> NPs) and functional SiO<sub>2</sub> NPs dispersed in: (<b>a</b>) ethanol and (<b>b</b>) methylene chloride.</p> Full article ">Figure 2
<p>Fourier transform infrared (FTIR) spectra of dried SiO<sub>2</sub> NPs.</p> Full article ">Figure 3
<p>Environmental scanning electron microscopy (ESEM) images of dried pristine SiO<sub>2</sub> NPs (<span class="html-italic">sample 1</span>) and dried SiO<sub>2</sub> NPs modified with long alkyl chain (<span class="html-italic">sample 5</span>), dispersed in ethanol.</p> Full article ">Figure 4
<p>TEM images of dried pristine SiO<sub>2</sub> NPs (<span class="html-italic">sample 1</span>) and dried SiO<sub>2</sub> NPs modified with long alkyl chain (<span class="html-italic">sample 5</span>), dispersed in ethanol.</p> Full article ">Figure 5
<p>Contact angle of the bilayer coatings (see <a href="#nanomaterials-07-00047-t003" class="html-table">Table 3</a>).</p> Full article ">Figure 6
<p>Atomic force microscopy (AFM) topographic images of structured coatings: monolayer hybrid hexadecyltrimethoxysilane/ tetramethoxysilane (C<sub>16</sub>TMS/TMOS) film (<span class="html-italic">coating C</span><sub>0</sub>), and bilayer coating (C<sub>16</sub>TMS/TMOS + 0.01 g of SiO<sub>2</sub> NPs functionalized with methoxydimethyloctylsilane (DMeC<sub>8</sub>MS) dispersed in 1 mL EtOH, <span class="html-italic">coating C</span><sub>5</sub>).</p> Full article ">
5946 KiB  
Article
Synthesis of Carbon Nanotubes in Thermal Plasma Reactor at Atmospheric Pressure
by Lukasz Szymanski, Zbigniew Kolacinski, Slawomir Wiak, Grzegorz Raniszewski and Lukasz Pietrzak
Nanomaterials 2017, 7(2), 45; https://doi.org/10.3390/nano7020045 - 18 Feb 2017
Cited by 17 | Viewed by 6606
Abstract
In this paper, a novel approach to the synthesis of the carbon nanotubes (CNTs) in reactors operating at atmospheric pressure is presented. Based on the literature and our own research results, the most effective methods of CNT synthesis are investigated. Then, careful selection [...] Read more.
In this paper, a novel approach to the synthesis of the carbon nanotubes (CNTs) in reactors operating at atmospheric pressure is presented. Based on the literature and our own research results, the most effective methods of CNT synthesis are investigated. Then, careful selection of reagents for the synthesis process is shown. Thanks to the performed calculations, an optimum composition of gases and the temperature for successful CNT synthesis in the CVD (chemical vapor deposition) process can be chosen. The results, having practical significance, may lead to an improvement of nanomaterials synthesis technology. The study can be used to produce CNTs for electrical and electronic equipment (i.e., supercapacitors or cooling radiators). There is also a possibility of using them in medicine for cancer diagnostics and therapy. Full article
(This article belongs to the Special Issue Nanoengineered Interfaces, Coatings and Structures by Plasma Techniques)
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<p>Setup of CVD reactor for CNT synthesis where: 1—furnace; 2—furnace heating elements; 3—substrate with growing nanotubes; 4—reaction tube [<a href="#B41-nanomaterials-07-00045" class="html-bibr">41</a>].</p> Full article ">Figure 2
<p>The general setup of the microwave plasma reactor where: 1—reaction chamber; 2—substrate with catalyst layer; 3—plasma nozzle; 4—plasma; 5—carbon nanotubes.</p> Full article ">Figure 3
<p>Block diagram of a test line where: 1—power supply; 2—generator; 3—circulator; 4—matching circuit, 5—reflectometer; 6—coaxial plasma head; 7—reaction chamber; 8—gas inlets; 9—cooling water.</p> Full article ">Figure 4
<p>Photo of reaction zone of the microwave plasma reactor for carbon nanotube (CNT) synthesis on a metal substrate where: 1—microwave plasma; 2—plasma head; 3—substrate feeder; 4—substrate.</p> Full article ">Figure 5
<p>Thermal decomposition of the mixture of 1000 sccm of ethylene with 3000 sccm of hydrogen.</p> Full article ">Figure 6
<p>Schematic diagram of the continuous microwave plasma system for CNT synthesis where: 1—reactor space; 2—substrate-metal strip; 3—microwave plasma head; 4—microwave plasma torch; 5—CNTs; 6—cassettes to move the metal substrate.</p> Full article ">Figure 7
<p>Photo of the plasma processing system where: 1—reactor chamber; 2—substrate-metal strip; 3—microwave plasma head; 4—microwave plasma torch (not visible); 5—CNTs (not visible); 6—cassettes to move the metal substrate.</p> Full article ">Figure 8
<p>SEM images of the steel with carbon nanotubes synthesized at different temperatures (<b>a</b>) 1020 K; (<b>b</b>) 1050 K; (<b>c</b>) 1070 K; (<b>d</b>) 1100 K; (<b>e</b>) 1120 K.</p> Full article ">Figure 9
<p>Plots of iron—(<b>a</b>) and carbon—(<b>b</b>) content versus synthesis temperature.</p> Full article ">Figure 10
<p>Energy-dispersive X-ray spectroscopy (EDX) analysis results for one of the specimens synthesized at 1070 K.</p> Full article ">Figure 11
<p>Thermogravimetry (TGA) thermographs of samples synthesized at (<b>a</b>) 1050 K; (<b>b</b>) 1070 K.</p> Full article ">Figure 12
<p>Transmission electron microscopy (TEM) images of Multi-Walled Carbon Nanotubes (MWCNTs) obtained during synthesis at (<b>a</b>) 1050 K; (<b>b</b>) 1070 K, respectively.</p> Full article ">
14792 KiB  
Article
In Vitro and In Vivo Evaluation of a Three-Dimensional Porous Multi-Walled Carbon Nanotube Scaffold for Bone Regeneration
by Manabu Tanaka, Yoshinori Sato, Mei Zhang, Hisao Haniu, Masanori Okamoto, Kaoru Aoki, Takashi Takizawa, Kazushige Yoshida, Atsushi Sobajima, Takayuki Kamanaka, Hiroyuki Kato and Naoto Saito
Nanomaterials 2017, 7(2), 46; https://doi.org/10.3390/nano7020046 - 17 Feb 2017
Cited by 42 | Viewed by 6775
Abstract
Carbon nanotubes (CNTs) have attracted a great deal of attention for the biological and medical science fields because of their characteristic physical and biological properties. In this study, we investigated the capacity of the 3D porous CNT scaffold (CNT porous block; CNTp) for [...] Read more.
Carbon nanotubes (CNTs) have attracted a great deal of attention for the biological and medical science fields because of their characteristic physical and biological properties. In this study, we investigated the capacity of the 3D porous CNT scaffold (CNT porous block; CNTp) for bone regenerative medicine. Surface observations using a scanning electron microscope (SEM), crystal depositions on the surface of CNTps immersed in simulated body fluid (SBF), and evaluations of protein adsorption and controlled releasing were conducted to assess physical properties. The cell proliferation and cell morphology were observed using SEM and fluorescent microscopy. CNTps were implanted into critical-size mouse calvarial defects and evaluated for their osteoconductive ability and in vivo controlled release of recombinant human BMP-2 (rhBMP-2). Interconnected porous HA ceramics (IP-CHAs) were used for comparison. CNTps have multiporous structures with interporous connections with networks of multiwalled CNTs. Crystals containing calcium and phosphate were deposited in CNTps and on the surface of the CNT networks by immersing CNTps in SBF. CNTps adsorbed more significantly and released protein more gradually than IP-CHAs. Preosteoblasts seeded onto CNTps filled pores with stretched actin filaments and filopodia. Compared with IP-CHAs, CNTps showed significantly higher cell proliferation, better osteoconduction, and more bone generation with rhBMP-2. In this study, CNTps demonstrated good osteoconductive ability, cell attachment and proliferation capacity, and growth factor retaining ability. CNTps have the potential not only as artificial bones for the treatment of bone defects, but also as scaffolds for regenerative medicine using tissue engineering approaches. Full article
(This article belongs to the Special Issue Nanofibrous Scaffolds for Biomedical Application)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Scanning electron microscope (SEM) image of (<b>a</b>,<b>b</b>) carbon nanotube (CNT) porous block (CNTp) and (<b>c</b>,<b>d</b>) interconnected porous HA ceramic (IP-CHA). Original magnification is 250× for (<b>a</b>,<b>c</b>) and 20,000× for (<b>b</b>,<b>d</b>). White arrows: interporous connections.</p> Full article ">Figure 2
<p>The stress-strain curves (<b>a</b>); maximum compressive strength (<b>b</b>); Young’s modulus (<b>c</b>); and energy to failure (<b>d</b>) of the IP-CHA and CNTp. Mean values were compared using Student’s <span class="html-italic">t</span> test (<span class="html-italic">n</span> = 3).</p> Full article ">Figure 3
<p>(<b>a</b>) SEM image of hydroxyapatite-like crystal formation on CNTp scaffolds; (<b>b</b>) SEM image of a non-treated IP-CHA; (<b>c</b>,<b>d</b>) EDS on marked area revealed Ca, P, O in the crystal on (<b>c</b>) CNTp and (<b>d</b>) the surface of non-treated IP-CHA; (<b>e</b>) Ca/P ratio of the crystals appeared on the surface of CNTp and IP-CHA. Mean values were compared using Student’s <span class="html-italic">t</span> test (<span class="html-italic">n</span> = 5).</p> Full article ">Figure 4
<p>Qualitative protein adsorption profiles. Mean values were compared using Student’s <span class="html-italic">t</span> test (<span class="html-italic">n</span> = 3).</p> Full article ">Figure 5
<p>Qualitative protein released from scaffolds. Graph shows release of bovine serum albumin (BSA) from CNTp and IP-CHA. Mean values were compared using Student’s <span class="html-italic">t</span> test (<span class="html-italic">n</span> = 5).</p> Full article ">Figure 6
<p>Degradation assay. Graph shows weight loss of CNTps and IP-CHAs immersed in PBS for 21 days. Mean values were compared using two-way ANOVA (<span class="html-italic">n</span> = 5).</p> Full article ">Figure 7
<p>MC3T3-E1 cells spreading on IP-CHA and CNTp scaffolds. Cells on (<b>a</b>,<b>c</b>,<b>e</b>) IP-CHA or (<b>b</b>,<b>d</b>,<b>f</b>) CNTp. SEM images of (<b>a</b>,<b>c</b>) IP-CHA and (<b>b</b>,<b>d</b>) CNTp. Original magnification is 2000× for (<b>a</b>,<b>b</b>) and 20,000× for (<b>c</b>,<b>d</b>). Cells labeled for actin filaments (red) and nucleus (blue) of (<b>e</b>) IP-CHA and (<b>f</b>) CNTp.</p> Full article ">Figure 8
<p>Cytotoxicity. Graph shows the number of cells per field counted on the surface of the CNTp and the IP-CHA (<b>a</b>). Mean values were compared using Student’s <span class="html-italic">t</span> test (<span class="html-italic">n</span> = 7). N.S.: Not Significant. Viable cells were stained with calcein AM (acetoxymethyl) and fluoresced green, while dead cells were stained with EthD-III and fluoresced red. Most of MC3T3-E1 cells were alive on CNTp (<b>b</b>,<b>c</b>) and IP-CHA (<b>d</b>,<b>e</b>) scaffolds at day 1 (<b>b</b>,<b>d</b>) and day 3 (<b>c</b>,<b>f</b>). White bars: 100 µm.</p> Full article ">Figure 9
<p>Alkaline Phosphatase (ALP) activity. Graph shows the ALP activity of the MC3T3-E1 cells cultured in the presence or absence of rhMP-2 on the surface of the CNTp and the IP-CHA. Mean values were compared using Student’s <span class="html-italic">t</span> test (<span class="html-italic">n</span> = 4).</p> Full article ">Figure 10
<p>(<b>a</b>) Micro-CT and histological image of empty control, IP-CHA, and CNTp scaffold implanted in the calvarial defects of ddY mice for 12 weeks; (<b>b</b>) A bar diagram showing the newly formed bone area/20× field in the calvarial defect of ddY mice implanted with each scaffold for 12 weeks. Mean values were compared using one-way ANOVA followed by Tukey’s post hoc test (<span class="html-italic">n</span> = 7). N.S.: Not Significant.</p> Full article ">Figure 11
<p>(<b>a</b>) Micro-CT and histological image of empty control, IP-CHA, and CNTp scaffolds combined with rhBMP-2, implanted in the calvarial defects of ddY mice for three weeks; (<b>b</b>) A bar diagram showing the newly formed bone area/20× field in the calvarial defect of ddY mice implanted with rhBMP-2 supplemented scaffolds. Mean values were compared using one-way ANOVA, followed by Tukey’s post-hoc test (<span class="html-italic">n</span> = 5).</p> Full article ">
3833 KiB  
Review
Recent Advances in Research on the Synthetic Fiber Based Silica Aerogel Nanocomposites
by Agnieszka Ślosarczyk
Nanomaterials 2017, 7(2), 44; https://doi.org/10.3390/nano7020044 - 16 Feb 2017
Cited by 61 | Viewed by 7923
Abstract
The presented paper contains a brief review on the synthesis and characterization of silica aerogels and its nanocomposites with nanofibers and fibers based on a literature study over the past twenty years and my own research. Particular attention is focused on carbon fiber-based [...] Read more.
The presented paper contains a brief review on the synthesis and characterization of silica aerogels and its nanocomposites with nanofibers and fibers based on a literature study over the past twenty years and my own research. Particular attention is focused on carbon fiber-based silica aerogel nanocomposites. Silica aerogel is brittle in nature, therefore, it is necessary to improve this drawback, e.g., by polymer modification or fiber additives. Nevertheless, there are very few articles in the literature devoted to the synthesis of silica aerogel/fiber nanocomposites, especially those focusing on carbon fibers and nanofibers. Carbon fibers are very interesting materials, namely due to their special properties: high conductivity, high mechanical properties in relation to very low bulk densities, high thermal stability, and chemical resistance in the silica aerogel matrix, which can help enhance silica aerogel applications in the future. Full article
(This article belongs to the Special Issue Textiles Nanotechnology)
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<p>(<b>a</b>) Transmission electron microscopy (TEM) picture of silica aerogel from Tetraethyloorthosilane (TEOS) supercritically dried in CO<sub>2</sub>; (<b>b</b>) adsorption/desorption isotherms of N<sub>2</sub> for silica aerogel (curve shape corresponds to the characteristic mesoporous structure).</p> Full article ">Figure 2
<p>(<b>a</b>) Scanning electron microscopy (SEM) picture of silica aerogel blanket; (<b>b</b>) Silica aerogel granules.</p> Full article ">Figure 3
<p>Scheme of different fibers used as reinforcements in silica aerogel nanocomposites.</p> Full article ">Figure 4
<p>SEM images of carbon microfibers. (<b>a</b>) in bulk; (<b>b</b>) cross-section of single fiber.</p> Full article ">Figure 5
<p>(<b>a</b>) Fourier transform infrared spectroscopy (FTIR) and (<b>b</b>) TG curves of carbon fiber-based silica aerogels synthesized from TEOS precursor in ambient pressure drying (1—pure aerogel, 2—with unmodified carbon microfibers, 3—with modified carbon microfibers).</p> Full article ">Figure 6
<p>(<b>a</b>) SEM pictures of carbon fiber-based silica aerogel; (<b>b</b>) the surface of carbon microfibers covered by nanoparticles of the silica aerogel.</p> Full article ">
1956 KiB  
Article
Lipoic Acid Gold Nanoparticles Functionalized with Organic Compounds as Bioactive Materials
by Ioana Turcu, Irina Zarafu, Marcela Popa, Mariana Carmen Chifiriuc, Coralia Bleotu, Daniela Culita, Corneliu Ghica and Petre Ionita
Nanomaterials 2017, 7(2), 43; https://doi.org/10.3390/nano7020043 - 16 Feb 2017
Cited by 27 | Viewed by 8738
Abstract
Water soluble gold nanoparticles protected by lipoic acid were obtained and further functionalized by standard coupling reaction with 1-naphtylamine, 4-aminoantipyrine, and 4′-aminobenzo-15-crown-5 ether. Derivatives of lipoic acid with 1-naphtylamine, 4-aminoantipyrine, and 4′-aminobenzo-15-crown-5 ether were also obtained and characterized. All these were tested for [...] Read more.
Water soluble gold nanoparticles protected by lipoic acid were obtained and further functionalized by standard coupling reaction with 1-naphtylamine, 4-aminoantipyrine, and 4′-aminobenzo-15-crown-5 ether. Derivatives of lipoic acid with 1-naphtylamine, 4-aminoantipyrine, and 4′-aminobenzo-15-crown-5 ether were also obtained and characterized. All these were tested for their antimicrobial activity, as well as for their influence on mammalian cell viability and cellular cycle. In all cases a decreased antimicrobial activity of the obtained bioactive nanoparticles was observed as compared with the organic compounds, proving that a possible inactivation of the bioactive groups could occur during functionalization. However, both the gold nanoparticles as well as the functionalized bioactive nanosystems proved to be biocompatible at concentrations lower than 50 µg/mL, as revealed by the cellular viability and cell cycle assay, demonstrating their potential for the development of novel antimicrobial agents. Full article
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Synthesis of lipoic acid (LA) Au NPs (<b>left</b>) and their transmission electron microscopy (TEM) image (<b>right</b>). Scale bar 10 nm.</p> Full article ">Figure 2
<p><b>Top</b>: Functionalization of Au NPs (<b>I</b>) with 1-naphtylamine, 4-aminoantipyrine, and 4′-amino-benzo-crown-5, yielding samples <b>II</b>–<b>IV</b>; <b>Bottom</b>: TEM images of samples <b>II</b>, <b>III</b>, and <b>IV</b>, respectively (scale bar 10 nm).</p> Full article ">Figure 3
<p>Synthesis of the compounds <b>V</b>–<b>VII</b> starting from LA.</p> Full article ">Figure 4
<p>Viability (%) of HeLa cells after 24 h treatment with different concentrations of the obtained nanoparticles.</p> Full article ">Figure 5
<p>Flow cytometry diagrams of the HeLa cells’ cycle analysis grown in the presence of the tested nanoparticles.</p> Full article ">
4801 KiB  
Article
Ag Nanoparticles‐Modified 3D Graphene Foam for Binder‐Free Electrodes of Electrochemical Sensors
by Tao Han, Jianli Jin, Congxu Wang, Youyi Sun, Yinghe Zhang and Yaqing Liu
Nanomaterials 2017, 7(2), 40; https://doi.org/10.3390/nano7020040 - 16 Feb 2017
Cited by 37 | Viewed by 6231
Abstract
Ag nanoparticles‐modified 3D graphene foam was synthesized through a one‐step in‐situ approach and then directly applied as the electrode of an electrochemical sensor. The composite foam electrode exhibited electrocatalytic activity towards Hg(II) oxidation with high limit of detection and sensitivity of 0.11 μM [...] Read more.
Ag nanoparticles‐modified 3D graphene foam was synthesized through a one‐step in‐situ approach and then directly applied as the electrode of an electrochemical sensor. The composite foam electrode exhibited electrocatalytic activity towards Hg(II) oxidation with high limit of detection and sensitivity of 0.11 μM and 8.0 μA/μM, respectively. Moreover, the composite foam electrode for the sensor exhibited high cycling stability, long‐term durability and reproducibility. These results were attributed to the unique porous structure of the composite foam electrode, which enabled the surface of Ag nanoparticles modified reduced graphene oxide (Ag NPs modified rGO) foam to become highly accessible to the metal ion and provided more void volume for the reaction with metal ion. This work not only proved that the composite foam has great potential application in heavy metal ions sensors, but also provided a facile method of gram scale synthesis 3D electrode materials based on rGO foam and other electrical active materials for various applications. Full article
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<p>(<b>A</b>) X-Ray diffraction (XRD) and (<b>B</b>) Raman spectra of pure reduced graphene oxide (rGO) foam and Ag nanoparticles (Ag NPs)/rGO composite foam.</p> Full article ">Figure 2
<p>Low-magnification scanning electron microscopy (SEM) images of (<b>A</b>) rGO foam and (<b>B</b>) Ag NPs/rGO composite foam; (<b>C</b>) and (<b>D</b>) are the enlarged view of the black square dashed box marked in (<b>A</b>,<b>B</b>), respectively. The inset of (<b>A</b>,<b>B</b>) are digital photographs of foams. Energy dispersive spectrometer (EDS) spectra of (<b>E</b>) rGO foam and (<b>F</b>) Ag NPs/rGO composite foam. The inset of (<b>E</b>,<b>F</b>) are elemental mapping image of rGO foam and Ag NPs/rGO composite foam, respectively; (<b>G</b>) is the schematic diagram of the Ag NPs/rGO composite foam structure.</p> Full article ">Figure 3
<p>Nitrogen adsorption-desorption isotherm curve of (<b>A</b>) pure rGO foam and (<b>B</b>) AgNPs/rGO composite foam.</p> Full article ">Figure 4
<p>(<b>A</b>) Cyclic voltammetry (CV) and (<b>B</b>) electrochemical impedance spectroscopy (EIS) of pure rGO foam and Ag NPs/rGO composite foam (EIS parameters: potential, 0.21 V; frequency range, 100 kHz–0.1 Hz; amplitude, 5.0 mV); (<b>C</b>) Schematic representation of electrochemical detection toward Hg(II) by Ag NPs/rGO composite foam.</p> Full article ">Figure 5
<p>Square wave stripping voltammograms (SWASV) responses of (<b>A</b>) pure rGO foam and (<b>B</b>) Ag NPs/rGO composite foam electrode towards Hg(II) at different concentrations in 0.1 M NH<sub>3</sub> solution. The insets correspond to the calibration plots of foam electrodes.</p> Full article ">Figure 6
<p>(<b>A</b>) Interference studies of typical SWASV responses of 0.4 μM Hg(II) on Ag NPs/rGO composite foam electrode in 0.1 M NH<sub>3</sub> (<b>a</b>) without other metal ion, (<b>b</b>) in the presence of Cd(II), (<b>c</b>) in the presence of Cd(II) and Cu(II); (<b>B</b>) Interference studies of typical SWASV responses of 0.3 μM Hg(II) on Ag NPs/rGO composite foam electrode in 0.1 M NH<sub>3</sub> in the presence of Cd(II) with various concentration.</p> Full article ">Figure 7
<p>(<b>A</b>) SWASV responses of Ag NPs/rGO composite foam electrode towards Hg(II) from 1st cycle to 10th cycle; (<b>B</b>) SWASV responses of three Ag NPs/rGO composite foam electrode prepared at the same procedure; (<b>C</b>) EIS of Ag NPs/rGO composite foam electrode towards Hg(II) from 1st cycle to 10th cycle.</p> Full article ">
2613 KiB  
Review
Electrospun Nanofibres Containing Antimicrobial Plant Extracts
by Wanwei Zhang, Sara Ronca and Elisa Mele
Nanomaterials 2017, 7(2), 42; https://doi.org/10.3390/nano7020042 - 15 Feb 2017
Cited by 138 | Viewed by 10815
Abstract
Over the last 10 years great research interest has been directed toward nanofibrous architectures produced by electrospinning bioactive plant extracts. The resulting structures possess antimicrobial, anti-inflammatory, and anti-oxidant activity, which are attractive for biomedical applications and food industry. This review describes the diverse [...] Read more.
Over the last 10 years great research interest has been directed toward nanofibrous architectures produced by electrospinning bioactive plant extracts. The resulting structures possess antimicrobial, anti-inflammatory, and anti-oxidant activity, which are attractive for biomedical applications and food industry. This review describes the diverse approaches that have been developed to produce electrospun nanofibres that are able to deliver naturally-derived chemical compounds in a controlled way and to prevent their degradation. The efficacy of those composite nanofibres as wound dressings, scaffolds for tissue engineering, and active food packaging systems will be discussed. Full article
(This article belongs to the Special Issue Antimicrobial Nanomaterials and Nanotechnology)
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<p>(<b>a</b>) Number of papers published per year on electrospun nanofibres containing plant extracts. ** This count considers the first ten months of 2016; (<b>b</b>) Analysis of the results by subject area. Scopus database was used to determine the total number of publications, searching for “electrospinning” plus “plant extract” or “essential oil”.</p> Full article ">Figure 2
<p>Scanning electron microscope images of electrospun fibres of (<b>a</b>) fluoroacrylic copolymer and (<b>b</b>) cellulose acetate. Reproduced with permission from [<a href="#B13-nanomaterials-07-00042" class="html-bibr">13</a>]. Copyright American Chemical Society, 2014.</p> Full article ">Figure 3
<p>(<b>a</b>) Release profile of chamomile from PCL (red circles), PCL/ polystyrene (PS) (green triangles) and PS (black squares) electrospun nanofibres over a time period of 48 h. PS samples showed a lower release if compared with PCL and PCL/PS samples. Antibacterial and antifungal properties of the composite PCL/PS fibre loaded with chamomile against (<b>b</b>) <span class="html-italic">S. aureus</span> and (<b>c</b>) <span class="html-italic">C. albicans</span>. Adapted with permission from [<a href="#B35-nanomaterials-07-00042" class="html-bibr">35</a>].</p> Full article ">Figure 4
<p>(<b>a</b>) Photographs of the skin of a mice 48 h after irradiation with ultraviolet light: untreated (no dressing) and treated with alginate (SA)-poly(ethylene oxide) (PEO) fibres (SA-PEO). An evident burn mark (red area) was visible for the animals without treatment, differently from mice treated with the electrospun dressings (no trace of erythema). Time course of the expression of (<b>b</b>) Interleukin-6 (IL-6) and (<b>c</b>) Interleukin-1β (IL-1β) for animals without treatment (UVB) and for animals treated with SA-PEO fibres (UVB-SA-PEO) and with SA-PEO fibre containing lavender essential oil (LO) (UVB-SA-PEO/LO). Adapted with permission from [<a href="#B50-nanomaterials-07-00042" class="html-bibr">50</a>].</p> Full article ">Figure 5
<p>(<b>a</b>) Chemical structure of β-CD and dimensions of α-CD, β-CD, γ-CD; (<b>b</b>) Schematic representations of (b) the formation of EG/CD-IC; (<b>c</b>) the PVA/EG/CD-IC solution; and (<b>d</b>) the electrospinning process leading to the production of PVA/EG/CD-IC fibres. Reproduced with permission from [<a href="#B86-nanomaterials-07-00042" class="html-bibr">86</a>]. Copyright American Chemical Society, 2013.</p> Full article ">
4336 KiB  
Review
NiCo2O4-Based Supercapacitor Nanomaterials
by Chenggang Wang, E Zhou, Weidong He, Xiaolong Deng, Jinzhao Huang, Meng Ding, Xianqi Wei, Xiaojing Liu and Xijin Xu
Nanomaterials 2017, 7(2), 41; https://doi.org/10.3390/nano7020041 - 15 Feb 2017
Cited by 146 | Viewed by 16359
Abstract
In recent years, the research on supercapacitors has ushered in an explosive growth, which mainly focuses on seeking nano-/micro-materials with high energy and power densities. Herein, this review will be arranged from three aspects. We will summarize the controllable architectures of spinel NiCo [...] Read more.
In recent years, the research on supercapacitors has ushered in an explosive growth, which mainly focuses on seeking nano-/micro-materials with high energy and power densities. Herein, this review will be arranged from three aspects. We will summarize the controllable architectures of spinel NiCo2O4 fabricated by various approaches. Then, we introduce their performances as supercapacitors due to their excellent electrochemical performance, including superior electronic conductivity and electrochemical activity, together with the low cost and environmental friendliness. Finally, the review will be concluded with the perspectives on the future development of spinel NiCo2O4 utilized as the supercapacitor electrodes. Full article
(This article belongs to the Special Issue Nanomaterials Based Fuel Cells and Supercapacitors)
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<p>The numbers of reported literature works related to supercapacitors from 2005 to 2015 (search from the Web of Science with “supercapacitor” as the keyword).</p> Full article ">Figure 2
<p>Schematic illustration of different types of supercapacitors: (<b>a</b>) electrical double-layer capacitors (EDLCs); (<b>b</b>) pseudocapacitor (PCs) (M represents the metal atom; if anions in the electrolyte take part in the reversible redox reaction, they will move in the opposite direction to the cations) (Reproduced with permission from [<a href="#B22-nanomaterials-07-00041" class="html-bibr">22</a>]. Copyright the Royal Society of Chemistry, 2014).</p> Full article ">Figure 3
<p>Ragone plots for various electrochemical energy storage systems (Reproduced with permission from [<a href="#B26-nanomaterials-07-00041" class="html-bibr">26</a>]. Copyright Elsevier, 2015).</p> Full article ">Figure 4
<p>(<b>a</b>) Crystallographic structure of the spinel NiCo<sub>2</sub>O<sub>4</sub> unit cell (Reproduced with permission from [<a href="#B35-nanomaterials-07-00041" class="html-bibr">35</a>]. Copyright the Royal Society of Chemistry, 2015); (<b>b</b>) <span class="html-italic">I</span>-<span class="html-italic">V</span> curves of the as-synthesized NiCo<sub>2</sub>O<sub>4</sub>, NiO and Co<sub>3</sub>O<sub>4</sub> samples (Reproduced with permission from [<a href="#B34-nanomaterials-07-00041" class="html-bibr">34</a>]. Copyright Elsevier, 2015).</p> Full article ">Figure 5
<p>(<b>a</b>) Scanning electron microscope (SEM) and transmission electron microscope (TEM) images of NiCo<sub>2</sub>O<sub>4</sub> nanowires (Reproduced with permission from [<a href="#B57-nanomaterials-07-00041" class="html-bibr">57</a>]. Copyright John Wiley and Sons, 2011); (<b>b</b>) SEM, TEM and selected area electron diffraction (SAED) of the porous NiCo<sub>2</sub>O<sub>4</sub> nanowires (Reproduced with permission from [<a href="#B52-nanomaterials-07-00041" class="html-bibr">52</a>]. Copyright the Royal Society of Chemistry, 2012); (<b>c</b>) TEM images of different reaction time and the schematic illustration of the formation process for hierarchical nickel cobalt layered double hydroxide tetragonal microtubes (Reproduced with permission from [<a href="#B52-nanomaterials-07-00041" class="html-bibr">52</a>]. Copyright the Royal Society of Chemistry, 2012).</p> Full article ">Figure 6
<p>(<b>a</b>) Different magnification SEM images of NiCo<sub>2</sub>O<sub>4</sub> nanowires arrays on carbon textiles (Reproduced with permission from [<a href="#B42-nanomaterials-07-00041" class="html-bibr">42</a>]. Copyright John Wiley and Sons, 2014); (<b>b</b>) SEM image of the Ni foam and NiCo<sub>2</sub>O<sub>4</sub> nanowires on Ni foam (Reproduced with permission from [<a href="#B58-nanomaterials-07-00041" class="html-bibr">58</a>]. Copyright the Royal Society of Chemistry, 2013).</p> Full article ">Figure 7
<p>SEM images at different magnifications: (<b>a</b>) NiCo<sub>2</sub>O<sub>4</sub> nanosheets on stainless-steel (Reproduced with permission from [<a href="#B45-nanomaterials-07-00041" class="html-bibr">45</a>]. Copyright Elsevier, 2010); (<b>b</b>) NiCo<sub>2</sub>O<sub>4</sub> nanosheets on Ni foam (Reproduced with permission from [<a href="#B49-nanomaterials-07-00041" class="html-bibr">49</a>]. Copyright John Wiley and Sons, 2013); (<b>c</b>) NiCo<sub>2</sub>O<sub>4</sub> nanocyclobenzene arrays on Ni foam (Reproduced with permission from [<a href="#B82-nanomaterials-07-00041" class="html-bibr">82</a>]. Copyright the Royal Society of Chemistry, 2014).</p> Full article ">Figure 8
<p>(<b>a</b>) SEM images of the NiCo<sub>2</sub>O<sub>4</sub> products under different pH values and schematic illustrations of the growth mechanism of the urchin-like NiCo<sub>2</sub>O<sub>4</sub> nanostructures (Reproduced with permission from [<a href="#B33-nanomaterials-07-00041" class="html-bibr">33</a>]. Copyright the Royal Society of Chemistry, 2012); (<b>b</b>) urchin-like NiCo<sub>2</sub>O<sub>4</sub> microspherical superstructures (Reproduced with permission from [<a href="#B83-nanomaterials-07-00041" class="html-bibr">83</a>]. Copyright Elsevier, 2012); (<b>c</b>) SEM image of as-synthesized NiCo<sub>2</sub>O<sub>4</sub> micro-spheres (Reproduced with permission from [<a href="#B44-nanomaterials-07-00041" class="html-bibr">44</a>]. Copyright the Royal Society of Chemistry, 2013); (<b>d</b>) SEM and TEM images of as-fabricated NiCo<sub>2</sub>O<sub>4</sub> (Reproduced with permission from [<a href="#B42-nanomaterials-07-00041" class="html-bibr">42</a>]. Copyright American Chemical Society, 2014); (<b>e</b>) SEM images of as-prepared materials (Reproduced with permission from [<a href="#B39-nanomaterials-07-00041" class="html-bibr">39</a>]. Copyright American Chemical Society, 2015); (<b>f</b>) TEM images of single-shelled and double-shelled NiCo<sub>2</sub>O<sub>4</sub> spheres (Reproduced with permission from [<a href="#B38-nanomaterials-07-00041" class="html-bibr">38</a>]. Copyright Nature Publishing Group, 2015); (<b>g</b>) typical FESEM and TEM images of NiCo<sub>2</sub>O<sub>4</sub> (Reproduced with permission from [<a href="#B62-nanomaterials-07-00041" class="html-bibr">62</a>]. Copyright John Wiley and Sons, 2015).</p> Full article ">Figure 9
<p>(<b>a</b>) SEM images of the NiCo<sub>2</sub>O<sub>4</sub>/mollusk shell-based macroporous carbon (MSBPC) composites (Reproduced with permission from [<a href="#B69-nanomaterials-07-00041" class="html-bibr">69</a>]. Copyright American Chemical Society, 2014); (<b>b</b>) SEM and TEM images of carbon fiber paper (CFP) after the growth of NiCo<sub>2</sub>O<sub>4</sub> nanosheets and Ni(OH)<sub>2</sub>/NiCo<sub>2</sub>O<sub>4</sub> nanosheets on CFP (Reproduced with permission from [<a href="#B86-nanomaterials-07-00041" class="html-bibr">86</a>]. Copyright American Chemical Society, 2013); (<b>c</b>) As-synthesized networked NiCo<sub>2</sub>O<sub>4</sub>/MnO<sub>2</sub> branched nanowire heterostructure (BNH) arrays on Ni foam (Reproduced with permission from [<a href="#B92-nanomaterials-07-00041" class="html-bibr">92</a>]. Copyright the Royal Society of Chemistry, 2015).</p> Full article ">
5126 KiB  
Article
An Enzymatic Glucose Sensor Composed of Carbon-Coated Nano Tin Sulfide
by Ren-Jei Chung, An-Ni Wang and Shiuan-Ying Peng
Nanomaterials 2017, 7(2), 39; https://doi.org/10.3390/nano7020039 - 15 Feb 2017
Cited by 21 | Viewed by 6678
Abstract
In this study, a biosensor, based on a glucose oxidase (GOx) immobilized, carbon-coated tin sulfide (SnS) assembled on a glass carbon electrode (GCE) was developed, and its direct electrochemistry was investigated. The carbon coated SnS (C-SnS) nanoparticle was prepared through a [...] Read more.
In this study, a biosensor, based on a glucose oxidase (GOx) immobilized, carbon-coated tin sulfide (SnS) assembled on a glass carbon electrode (GCE) was developed, and its direct electrochemistry was investigated. The carbon coated SnS (C-SnS) nanoparticle was prepared through a simple two-step process, using hydrothermal and chemical vapor deposition methods. The large reactive surface area and unique electrical potential of C-SnS could offer a favorable microenvironment for facilitating electron transfer between enzymes and the electrode surface. The structure and sensor ability of the proposed GOx/C-SnS electrode were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, UV–vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), and cyclic voltammetry study (CV). Full article
(This article belongs to the Special Issue Colloidal Quantum Dots (QDs) for Display, Solar Cells and Bio-Image Applications)
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<p>Scanning electron microscopy (SEM) images of (<b>a</b>) SnS<sub>2</sub> and (<b>b</b>) carbon-coated tin sulfide (SnS) powders.</p> Full article ">Figure 2
<p>X-ray diffraction (XRD) θ/2θ scan of (<b>a</b>) SnS<sub>2</sub> and (<b>b</b>) carbon-coated SnS powders.</p> Full article ">Figure 3
<p>Raman spectrums of (<b>a</b>) SnS<sub>2</sub> and (<b>b</b>) carbon-coated SnS powders.</p> Full article ">Figure 4
<p>Fourier transform infrared spectroscopy (FTIR) of carbon-coated SnS (C-SnS), glucose oxidase (GO<span class="html-italic"><sub>x</sub></span>), and GO<span class="html-italic"><sub>x</sub></span> on C-SnS.</p> Full article ">Figure 5
<p>UV–vis spectroscopy of carbon-coated SnS (C-SnS), glucose oxidase (GO<span class="html-italic"><sub>x</sub></span>), and GO<span class="html-italic"><sub>x</sub></span> on C-SnS.</p> Full article ">Figure 6
<p>The cyclic voltammetry (CV) profiles of different working electrodes were used to compare with the GO<span class="html-italic"><sub>x</sub></span>/SnS/GCE sensor, including bare glassy carbon electrode (GCE), C-SnS coating on GC (C-SnS/GCE), and GO<span class="html-italic"><sub>x</sub></span> on GC (GO<span class="html-italic"><sub>x</sub></span>/GCE) electrodes. The CV scan was carried out in 0.1 M PBS at a scan rate of 100 mV/s.</p> Full article ">Figure 7
<p>(<b>a</b>) CV profiles of the GO<span class="html-italic"><sub>x</sub></span>/SnS/GCE sensor under different scan rates and (<b>b</b>) the resultant oxidation and reduction plots.</p> Full article ">Figure 8
<p>(<b>a</b>) CV profile of the GO<span class="html-italic"><sub>x</sub></span>/SnS/GCE sensor under different pH values, and (<b>b</b>) the linear plotting of the E/V vs. pH values.</p> Full article ">Figure 9
<p>Current per unit area vs. glucose concentration of the GO<span class="html-italic"><sub>x</sub></span>/SnS/GCE sensor.</p> Full article ">Figure 10
<p>Amperometric response of the GO<span class="html-italic"><sub>x</sub></span>/SnS/GCE electrode to 0.1 mM glucose, as well as 0.1 mM interferents of uric acid (UA) and citric acid (CA).</p> Full article ">Figure 11
<p>The performance stability of the C-SnS/GO<span class="html-italic"><sub>x</sub></span>/GCE sensor for 7 days, where 0.1 mM glucose was used.</p> Full article ">
7110 KiB  
Article
Synthesis, Characterization, and Biological Evaluation of Nanostructured Hydroxyapatite with Different Dimensions
by Zhen Geng, Qin Yuan, Xianglong Zhuo, Zhaoyang Li, Zhenduo Cui, Shengli Zhu, Yanqin Liang, Yunde Liu, Huijing Bao, Xue Li, Qianyu Huo and Xianjin Yang
Nanomaterials 2017, 7(2), 38; https://doi.org/10.3390/nano7020038 - 15 Feb 2017
Cited by 27 | Viewed by 6190
Abstract
Nanosized hydroxyapatite (HA) is a promising candidate for a substitute for apatite in bone in biomedical applications. Furthermore, due to its excellent bone bioactivity, nanosized strontium-substituted HA (SrHA) has aroused intensive interest. However, the size effects of these nanoparticles on cellular bioactivity should [...] Read more.
Nanosized hydroxyapatite (HA) is a promising candidate for a substitute for apatite in bone in biomedical applications. Furthermore, due to its excellent bone bioactivity, nanosized strontium-substituted HA (SrHA) has aroused intensive interest. However, the size effects of these nanoparticles on cellular bioactivity should be considered. In this study, nanosized HA and SrHA with different dimensions and crystallization were synthesized by hydrothermal methods. The phase, crystallization and chemical composition were analyzed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR), respectively. The morphology was observed under field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The degradation behaviors of the samples were monitored by determining the ions release profile with inductively coupled plasma mass spectrometry (ICP-MS). The releasing behavior of Ca2+ and Sr2+ showed that the degradation rate was proportional to the specific surface area and inversely proportional to crystallization. The in vitro experiment evaluated by MG63 cells showed that SrHA nanorods with a length greater than 100 nm had the best biological performance both in cell proliferation and differentiation (* p < 0.05 compared with HA-1 and SrHA-1; * p < 0.01 compared with HA-2). In addition, HA nanoparticles with a lower aspect ratio had better bioactivity than higher ones (* p < 0.05). This study demonstrated that nanosized HA and SrHA with subtle differences (including dimensions, crystallization, specific surface area, and degradation rate) could affect the cellular growth and thus might have an impact on bone growth in vivo. This work provides a view of the role of nano-HAs as ideal biocompatible materials in future clinical applications. Full article
(This article belongs to the Special Issue Cytotoxicity of Nanoparticles)
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Full article ">Figure 1
<p>X-ray diffraction (XRD) patterns of the prepared samples. SrHAs exhibited sharper diffraction peaks than those of HAs, those indicating a higher crystallinity.</p> Full article ">Figure 2
<p>Fourier-transform infrared spectroscopy (FT-IR) spectra of the prepared powders. The main component of all samples is phosphate. SrHAs showed strengthened carbonate absorption intensity compared to HAs.</p> Full article ">Figure 3
<p>Scanning electron microscopy (SEM) images of the synthesized samples: (<b>a</b>) HA-1; (<b>b</b>) HA-2; (<b>c</b>) SrHA-1; and (<b>d</b>) SrHA-2. SrHA-2 exhibited a nanorod shape and had a larger size than the other three.</p> Full article ">Figure 4
<p>Transmission electron microscopy (TEM) and selected-area electron diffraction (SAED) patterns of the synthesized samples: (<b>a</b>) HA-1; (<b>b</b>) HA-2; (<b>c</b>) SrHA-1; and (<b>d</b>) SrHA-2.</p> Full article ">Figure 5
<p>(<b>a</b>) Length distribution of HA and SrHA; (<b>b</b>) Width distribution of HA and SrHA; (<b>c</b>) Aspect ratio distribution of HA and SrHA.</p> Full article ">Figure 6
<p>SEM morphology of synthesized coatings: (<b>a</b>) HA-1, (<b>b</b>) HA-2, (<b>c</b>) SrHA-1, and (<b>d</b>) SrHA-2. The SrHA-2 coating showed a nanorod morphology (inset), which was different from the other three (nanoparticles).</p> Full article ">Figure 7
<p>Cumulative Ca<sup>2+</sup> (red line) and Sr<sup>2+</sup> (black line) ion release as a function of time.</p> Full article ">Figure 8
<p>MG63 cell adhesion and distribution after one (<b>a</b>–<b>d</b>) or three (<b>e</b>–<b>h</b>) days of incubation. (<b>a</b>,<b>e</b>) HA-1, (<b>b</b>,<b>f</b>) HA-2, (<b>c</b>,<b>g</b>) SrHA-1, and (<b>d</b>,<b>h</b>) SrHA-2. (<b>i</b>) MG63 cell proliferation after one, three, and seven days of incubation measured by colorimetric MTT assay. (<b>j</b>) ALP activity of MG63 cells after three, seven, or 14 days of incubation. Statistically significant differences (<span class="html-italic">* p</span> &lt; 0.05, <span class="html-italic">** p</span> &lt; 0.01).</p> Full article ">Figure 9
<p>Gene expressions of MG63 cells cultured on different samples after incubation for three, seven, or 14 days: (<b>a</b>) ALP; (<b>b</b>) Runx2; (<b>c</b>) OCN. Statistically significant differences (* <span class="html-italic">p</span> &lt; 0.05).</p> Full article ">Scheme 1
<p>Nanostructured hydroxyapatite with different dimensions via different routes.</p> Full article ">
1702 KiB  
Article
Evidence of Protein Adsorption in Pegylated Liposomes: Influence of Liposomal Decoration
by Marc Sangrà, Joan Estelrich, Raimon Sabaté, Alba Espargaró and Maria Antònia Busquets
Nanomaterials 2017, 7(2), 37; https://doi.org/10.3390/nano7020037 - 10 Feb 2017
Cited by 23 | Viewed by 5695
Abstract
In order to contribute to a better knowledge of the events involved in the formation of the protein corona when nanoparticles (NPs) come in contact with proteins, we report a study about the changes on the physicochemical properties of pristine, PEGylated and Cyclic [...] Read more.
In order to contribute to a better knowledge of the events involved in the formation of the protein corona when nanoparticles (NPs) come in contact with proteins, we report a study about the changes on the physicochemical properties of pristine, PEGylated and Cyclic Arginine-Glycine-Aspartate peptide (RGD)-functionalized large unilamelar liposomes (LUVs) or magnetoliposomes (MLs) upon incubation with Bovine Serum Albumin (BSA). The main phospholipid component of both LUVs and MLs was l-α-phosphatydylcholine (PC) or 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) with 20% of cholesterol. The most obvious indication of the interaction of BSA-nanosystems is given by changes in the hydrodynamic diameter of the particles but other evidence is needed to corroborate the process. Our findings indicate that size modification is a process that is accomplished in few hours and that is strongly dependent not only on the surface decoration but also of the lipid composition of both LUVs and MLs. Fluorescence quenching experiments as well as cryogenic transmission electron microscopy (Cryo-TEM) images assessed these changes and confirmed that although each system has to be studied in a particular way, we can establish three distinctive features that turn into more reactive systems: (a) compositions containing PC compared with their DMPC counterparts; (b) the presence of PEG and/or RGD compared to the pristine counterparts; and (c) the presence of SPIONs: MLs show higher interaction than LUVs of the same lipid composition. Consequently, PEGylation (that is supposed to make stealth NPs) actually fails in preventing complete protein binding. Full article
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<p>Cryo-TEM images of: (<b>a</b>) PC-RGD-LUVs; (<b>b</b>) PC-RGD-MLs; (<b>c</b>) PC -RGD-MLs incubated 24 h with BSA; (<b>d</b>) DMPC-RGD-LUVs; (<b>e</b>) DMPC-RGD-MLs; and (<b>f</b>) DMPC -RGD-MLs incubated 24 h with BSA. Scale in all the images is 100 nm except for (<b>c</b>) which is 500 nm.</p> Full article ">Figure 2
<p>SDS-PAGE of: (<b>left</b>) LUVs and (<b>right</b>) MLVs after 24 h incubation with BSA at 37 °C. The order of the bands is from left to right: 1: Bare PC; 2: bare PC/Chol; 3: PEGylated-PC; 4: RGD-PC; 5: bare DMPC; 6: bare DMPC/Chol; 7: PEGylated-DMPC; and 8: RGD-DMPC.</p> Full article ">Figure 3
<p>Fluorescence spectra obtained after the incubation of BSA with PC or DMPC LUVs or MLs. (<b>a</b>) LUVs PC/Chol (8:2); (<b>b</b>) MLs PC/Chol (8:2); (<b>c</b>) LUVs DMPC/Chol (8:2); (<b>d</b>) MLs DMPC/Chol (8:2); (<b>e</b>) LUVs PC/Chol/PEG (8:2:0.3); (<b>f</b>) MLVs PC/Chol/PEG (8:2:0.3); (<b>g</b>) LUVs DMPC/Chol/PEG (8:2:0.3); (<b>h</b>) MLVs DMPC/Chol/PEG (8:2:0.3). The black line corresponds to the spectrum of 5 µM free BSA while the rest refer to the recordings after consecutive additions of 5 µL of 20 mM LUVs or MLs. The arrow indicates the direction of increase in LUVs or MLs concentration ranging from 62 to 370 µM into the reaction cuvette. λ<sub>exc</sub>: 280 nm. The intensity of the emission band at 338 nm corresponding to the tryptophan was used for the calculation of the Stern-Volmer constant (<span class="html-italic">K</span><sub>SV</sub>) [<a href="#B51-nanomaterials-07-00037" class="html-bibr">51</a>].</p> Full article ">Figure 3 Cont.
<p>Fluorescence spectra obtained after the incubation of BSA with PC or DMPC LUVs or MLs. (<b>a</b>) LUVs PC/Chol (8:2); (<b>b</b>) MLs PC/Chol (8:2); (<b>c</b>) LUVs DMPC/Chol (8:2); (<b>d</b>) MLs DMPC/Chol (8:2); (<b>e</b>) LUVs PC/Chol/PEG (8:2:0.3); (<b>f</b>) MLVs PC/Chol/PEG (8:2:0.3); (<b>g</b>) LUVs DMPC/Chol/PEG (8:2:0.3); (<b>h</b>) MLVs DMPC/Chol/PEG (8:2:0.3). The black line corresponds to the spectrum of 5 µM free BSA while the rest refer to the recordings after consecutive additions of 5 µL of 20 mM LUVs or MLs. The arrow indicates the direction of increase in LUVs or MLs concentration ranging from 62 to 370 µM into the reaction cuvette. λ<sub>exc</sub>: 280 nm. The intensity of the emission band at 338 nm corresponding to the tryptophan was used for the calculation of the Stern-Volmer constant (<span class="html-italic">K</span><sub>SV</sub>) [<a href="#B51-nanomaterials-07-00037" class="html-bibr">51</a>].</p> Full article ">
4707 KiB  
Article
Non-Enzymatic Glucose Sensor Composed of Carbon-Coated Nano-Zinc Oxide
by Ren-Jei Chung, An-Ni Wang, Qing-Liang Liao and Kai-Yu Chuang
Nanomaterials 2017, 7(2), 36; https://doi.org/10.3390/nano7020036 - 10 Feb 2017
Cited by 65 | Viewed by 7396
Abstract
Nowadays glucose detection is of great importance in the fields of biological, environmental, and clinical analyzes. In this research, we report a zinc oxide (ZnO) nanorod powder surface-coated with carbon material for non-enzymatic glucose sensor applications through a hydrothermal process and chemical vapor [...] Read more.
Nowadays glucose detection is of great importance in the fields of biological, environmental, and clinical analyzes. In this research, we report a zinc oxide (ZnO) nanorod powder surface-coated with carbon material for non-enzymatic glucose sensor applications through a hydrothermal process and chemical vapor deposition method. A series of tests, including crystallinity analysis, microstructure observation, and electrochemical property investigations were carried out. For the cyclic voltammetric (CV) glucose detection, the low detection limit of 1 mM with a linear range from 0.1 mM to 10 mM was attained. The sensitivity was 2.97 μA/cm2mM, which is the most optimized ever reported. With such good analytical performance from a simple process, it is believed that the nanocomposites composed of ZnO nanorod powder surface-coated with carbon material are promising for the development of cost-effective non-enzymatic electrochemical glucose biosensors with high sensitivity. Full article
(This article belongs to the Special Issue Colloidal Quantum Dots (QDs) for Display, Solar Cells and Bio-Image Applications)
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<p>Scheme of the chemical vapor deposition (CVD) process.</p> Full article ">Figure 2
<p>X-ray diffraction (XRD) pattern of the as-synthesized zinc oxide (ZnO) nanorod powder.</p> Full article ">Figure 3
<p>Micrographs of (<b>a</b>) ZnO and (<b>b</b>) ZnO (ZnO@C) nanorod powder.</p> Full article ">Figure 4
<p>(<b>a</b>) Transmission electron microscopy (TEM) image; (<b>b</b>) high-resolution transmission electron microscopy (HRTEM) image; and (<b>c</b>) selected area electron diffraction (SAED) pattern of ZnO (ZnO@C) nanorod powder.</p> Full article ">Figure 5
<p>The Raman spectra of ZnO and carbon-coated ZnO nanorod powder. The Raman spectrum of ZnO was labeled according to the B1, E2, and E1 vibration modes, and those of carbon are D and G.</p> Full article ">Figure 6
<p>Cyclic voltammetric (CV) profiles of GC, ZnO/GC, and ZnO@C/GC electrodes in 1 M NaOH<sub>(aq)</sub> solution.</p> Full article ">Figure 7
<p>CV profiles of GC, ZnO/GC and ZnO@C/GC electrodes for 1 mM glucose sensing.</p> Full article ">Figure 8
<p>CV profiles under different scan rates in 1 M NaOH (aq) solution and 1 mM glucose.</p> Full article ">Figure 9
<p>CV profile of ZnO@C/GC electrodes under different pH values.</p> Full article ">Figure 10
<p>(<b>a</b>) The current vs. time curve of ZnO@C/GC electrode in 1 M NaOH<sub>(aq)</sub> and glucose<sub>(aq)</sub> solution, where the glucose<sub>(aq)</sub> was added 1 mM per 100 s; (<b>b</b>) The corresponding linear fitting of the stabilized current and glucose concentration from (<b>a</b>).</p> Full article ">Figure 11
<p>Amperometric response of ZnO@C/GC electrode to 1.0 µM glucose, as well as 1 mM interferents of citric acid (CA), uric acid (UA), and dopamine (DA).</p> Full article ">
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Article
Eu, Gd-Codoped Yttria Nanoprobes for Optical and T1-Weighted Magnetic Resonance Imaging
by Timur Sh Atabaev, Jong Ho Lee, Yong Cheol Shin, Dong-Wook Han, Ki Seok Choo, Ung Bae Jeon, Jae Yeon Hwang, Jeong A. Yeom, Hyung-Kook Kim and Yoon-Hwae Hwang
Nanomaterials 2017, 7(2), 35; https://doi.org/10.3390/nano7020035 - 10 Feb 2017
Cited by 27 | Viewed by 4677
Abstract
Nanoprobes with multimodal functionality have attracted significant interest recently because of their potential applications in nanomedicine. This paper reports the successful development of lanthanide-doped Y2O3 nanoprobes for potential applications in optical and magnetic resonance (MR) imaging. The morphology, structural, and [...] Read more.
Nanoprobes with multimodal functionality have attracted significant interest recently because of their potential applications in nanomedicine. This paper reports the successful development of lanthanide-doped Y2O3 nanoprobes for potential applications in optical and magnetic resonance (MR) imaging. The morphology, structural, and optical properties of these nanoprobes were characterized by transmission electron microscope (TEM), field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), energy-dispersive X-ray (EDX), and photoluminescence (PL). The cytotoxicity test showed that the prepared lanthanide-doped Y2O3 nanoprobes have good biocompatibility. The obvious contrast enhancement in the T1-weighted MR images suggested that these nanoprobes can be used as a positive contrast agent in MRI. In addition, the clear fluorescence images of the L-929 cells incubated with the nanoprobes highlight their potential for optical imaging. Overall, these results suggest that prepared lanthanide-doped Y2O3 nanoprobes can be used for simultaneous optical and MR imaging. Full article
(This article belongs to the Special Issue Frontiers in Toxicity and Functionalization of Nanomaterials)
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<p>Transmission electron microscope (TEM) images of (<b>a</b>) bare Y<sub>2</sub>O<sub>3</sub>:Eu<sup>3+</sup>; (<b>b</b>) 3 mol % Gd<sup>3+</sup> codoped Y<sub>2</sub>O<sub>3</sub>:Eu<sup>3+</sup>; (<b>c</b>) 7 mol % Gd<sup>3+</sup> codoped Y<sub>2</sub>O<sub>3</sub>:Eu<sup>3+</sup>; and (<b>d</b>) 10 mol % Gd<sup>3+</sup> codoped Y<sub>2</sub>O<sub>3</sub>:Eu<sup>3+</sup>.</p> Full article ">Figure 2
<p>Photoluminescence (PL) emission spectra of prepared samples.</p> Full article ">Figure 3
<p>Longitudinal relaxivity rate R<sub>1</sub> vs. various concentrations of Gd-codoped nanoparticles measured at room-temperature. Inset is T<sub>1</sub>-weighted images of the 10 mol % Gd<sup>3+</sup> codoped nanoparticles at various concentrations (ppm).</p> Full article ">Figure 4
<p>Relative cell viability of L-929 cells exposed to increasing concentrations (0–250 ppm) of the 10 mol % Gd<sup>3+</sup> codoped nanoparticles. An asterisk (*) denotes a significant difference compared with the control, <span class="html-italic">p</span> &lt; 0.05.</p> Full article ">Figure 5
<p>Fluorescence micrograps (200×) of L-929 cells treated with 10 ppm of 10 mol % Gd<sup>3+</sup> codoped nanoparticles, followed by cell nuclei counterstaining with 10 μmol/L of 4’6-diamidino-2-phenylindole (DAPI). (<b>a</b>) Phase contrast image of the cells co-labelled with nanoparticles and DAPI; (<b>b</b>,<b>c</b>) Fluorescence images of the cells collected from DAPI (blue) and nanoprobes (red) respectively; (<b>d</b>) Merged image of (<b>b</b>,<b>c</b>).</p> Full article ">
960 KiB  
Article
Magnetic Nanovectors for the Development of DNA Blood-Stage Malaria Vaccines
by Fatin M. Nawwab Al-Deen, Sue D. Xiang, Charles Ma, Kirsty Wilson, Ross L. Coppel, Cordelia Selomulya and Magdalena Plebanski
Nanomaterials 2017, 7(2), 30; https://doi.org/10.3390/nano7020030 - 10 Feb 2017
Cited by 17 | Viewed by 6124
Abstract
DNA vaccines offer cost, flexibility, and stability advantages, but administered alone have limited immunogenicity. Previously, we identified optimal configurations of magnetic vectors comprising superparamagnetic iron oxide nanoparticles (SPIONs), polyethylenimine (PEI), and hyaluronic acid (HA) to deliver malaria DNA encoding Plasmodium yoelii (Py) merozoite [...] Read more.
DNA vaccines offer cost, flexibility, and stability advantages, but administered alone have limited immunogenicity. Previously, we identified optimal configurations of magnetic vectors comprising superparamagnetic iron oxide nanoparticles (SPIONs), polyethylenimine (PEI), and hyaluronic acid (HA) to deliver malaria DNA encoding Plasmodium yoelii (Py) merozoite surface protein MSP119 (SPIONs/PEI/DNA + HA gene complex) to dendritic cells and transfect them with high efficiency in vitro. Herein, we evaluate their immunogenicity in vivo by administering these potential vaccine complexes into BALB/c mice. The complexes induced antibodies against PyMSP119, with higher responses induced intraperitoneally than intramuscularly, and antibody levels further enhanced by applying an external magnetic field. The predominant IgG subclasses induced were IgG2a followed by IgG1 and IgG2b. The complexes further elicited high levels of interferon gamma (IFN-γ), and moderate levels of interleukin (IL)-4 and IL-17 antigen-specific splenocytes, indicating induction of T helper 1 (Th1), Th2, and Th17 cell mediated immunity. The ability of such DNA/nanoparticle complexes to induce cytophilic antibodies together with broad spectrum cellular immunity may benefit malaria vaccines. Full article
(This article belongs to the Special Issue Nanoparticles in Immunology)
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<p>Antibody responses induced by the different magnetic gene complexes compared via different routes of administration. BALB/c mice (<span class="html-italic">n</span> = 5/group) were immunised 3 times (3 weeks apart) with SPIONs/PEI/DNA + HA, SPIONs/PEI/DNA, or naked DNA via intraperitoneal (i.p.) and intramuscular (i.m.) administration (naked DNA via i.p. only), with or without the application of an external magnetic field. Two weeks after the final immunisation (day 56), sera were collected and pooled from each group, and measured for total antigen-specific IgG production by ELISA assay, and antibody titres were calculated (see Methods section). Data represented as antibody titre mean ± SD of 2 individual experiments. Statistical significance was designated as *** <span class="html-italic">p</span> &lt; 0.001, **** <span class="html-italic">p</span> &lt; 0.0001, ((w/M) with magnet, (wo/M) without magnet).</p> Full article ">Figure 2
<p>IgG subclasses induced by the SPIONs/PEI/DNA + HA complexes in vivo. BALB/c mice (<span class="html-italic">n</span> = 5/group) were immunised 3 times (3 weeks apart) with either SPIONs/PEI/DNA + HA, SPIONs/PEI/DNA, or naked DNA, via i.p. and i.m. administration (naked DNA via i.p. only), with or without the application of an external magnetic field. Two weeks after the final immunisation (day 56), sera from each mouse were collected and measured for antigen-specific IgG1 (<b>A</b>), IgG2a (<b>B</b>), and IgG2b (<b>C</b>) production by ELISA assay. Data represented as antibody titre mean ± SD (<span class="html-italic">n</span> = 5 mice). Statistical analysis was performed using one-way analysis of variance (ANOVA) and Tukey’s multiple comparison tests. Statistical significance was designated as ** <span class="html-italic">p</span> &lt; 0.01, *** <span class="html-italic">p</span> &lt; 0.001, **** <span class="html-italic">p</span> &lt; 0.0001, ((w/M) with magnet, (w/o M) without magnet).</p> Full article ">Figure 3
<p>Dendritic cell activation in spleen after injection with SPIONs/PEI/DNA + HA complexes via i.p. or i.m. administration (naked DNA via i.p. only), with or without the application of a magnetic field. Mice (BALB/c) were injected once via i.p. or i.m. route of injection. Forty-eight hours after injection, mice were sacrificed, spleens were harvested, and the levels (%) of CD86 marker in splenic DCs were assessed by flow cytometry. Data are presented as mean percentage of CD86-positive DCs ± SD for each group of treatment (<span class="html-italic">n</span> = 3 mice/group). Statistical analysis was performed via <span class="html-italic">t</span>-tests, * <span class="html-italic">p</span> ≤ 0.05.</p> Full article ">Figure 4
<p>Antigen-specific T cell responses induced by the SPIONs/PEI/DNA + HA complexes in vivo. BALB/c mice (<span class="html-italic">n</span> = 5/group) were immunised 3 times (3 weeks apart) with SPIONs/PEI/DNA + HA or naked DNA, via i.p. and i.m. administration, with or without the application of an external magnetic field. Two weeks after the final immunisation (day 56), mice were humanely sacrificed, and splenocytes were harvested and assayed for antigen-specific T cell responses, measured by the induction of IFN-γ, IL-4, and IL-17 cytokine production, upon stimulation with the recall antigen (recombinant EcPyMSP1<sub>19</sub>) in ELISpot assays. All data expressed as mean of spot-forming units (SFU)/million cells ± SD. (<b>A</b>) IFN-γ; (<b>B</b>) IL-4; (<b>C</b>) IL-17 responses. Statistical significance was designated as * <span class="html-italic">p</span> ≤ 0.05, ** <span class="html-italic">p</span> &lt; 0.01, **** <span class="html-italic">p</span> &lt; 0.0001.</p> Full article ">
3248 KiB  
Article
Synthesis of Multicolor Core/Shell NaLuF4:Yb3+/Ln3+@CaF2 Upconversion Nanocrystals
by Hui Li, Shuwei Hao, Chunhui Yang and Guanying Chen
Nanomaterials 2017, 7(2), 34; https://doi.org/10.3390/nano7020034 - 7 Feb 2017
Cited by 22 | Viewed by 7192
Abstract
The ability to synthesize high-quality hierarchical core/shell nanocrystals from an efficient host lattice is important to realize efficacious photon upconversion for applications ranging from bioimaging to solar cells. Here, we describe a strategy to fabricate multicolor core @ shell α-NaLuF4:Yb3+ [...] Read more.
The ability to synthesize high-quality hierarchical core/shell nanocrystals from an efficient host lattice is important to realize efficacious photon upconversion for applications ranging from bioimaging to solar cells. Here, we describe a strategy to fabricate multicolor core @ shell α-NaLuF4:Yb3+/Ln3+@CaF2 (Ln = Er, Ho, Tm) upconversion nanocrystals (UCNCs) based on the newly established host lattice of sodium lutetium fluoride (NaLuF4). We exploited the liquid-solid-solution method to synthesize the NaLuF4 core of pure cubic phase and the thermal decomposition approach to expitaxially grow the calcium fluoride (CaF2) shell onto the core UCNCs, yielding cubic core/shell nanocrystals with a size of 15.6 ± 1.2 nm (the core ~9 ± 0.9 nm, the shell ~3.3 ± 0.3 nm). We showed that those core/shell UCNCs could emit activator-defined multicolor emissions up to about 772 times more efficient than the core nanocrystals due to effective suppression of surface-related quenching effects. Our results provide a new paradigm on heterogeneous core/shell structure for enhanced multicolor upconversion photoluminescence from colloidal nanocrystals. Full article
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<p>The X-ray diffraction patterns of NaLuF<sub>4</sub>:Yb<sup>3+</sup>/Ln<sup>3+</sup> nanocrystals synthesized at different hydrothermal temperature: (a) 100 °C; (b) 120 °C; (c) 140 °C; (d) 160 °C; (e) 180 °C. All samples were prepared at F<sup>−</sup>/Ln<sup>3+</sup> = 4:1.</p> Full article ">Figure 2
<p>The X-ray diffraction patterns of NaLuF<sub>4</sub>:Yb<sup>3+</sup>/Er<sup>3+</sup> nanocrystals synthesized with molar ratio of F<sup>−</sup>/Re<sup>3+</sup> = (a) 4:1; (b) 3.5:1; (c) 3:1; (d) 2.5:1; (e) 2:1. (<span class="html-italic">T</span> = 140 °C).</p> Full article ">Figure 3
<p>(<b>a</b>) Schematic illustration of the epitaxial growth of CaF<sub>2</sub> shell on α-NaLuF<sub>4</sub>:Yb<sup>3+</sup>/Ln<sup>3+</sup> core nanoparticles (NPs); (<b>b</b>) TEM image of α-NaLuF<sub>4</sub>:Yb<sup>3+</sup>/Ln<sup>3+</sup> core nanocrystals prepared at F<sup>−</sup>/Re<sup>3+</sup> = 3:1 and <span class="html-italic">T</span> = 140 °C. TEM images of (<b>c</b>) NaLuF<sub>4</sub>:Yb<sup>3+</sup>/Er<sup>3+</sup>@CaF<sub>2</sub> core/shell upconversion nanocrystals (UCNCs); (<b>d</b>) α-NaLuF<sub>4</sub>:Yb<sup>3+</sup>/Ho<sup>3+</sup>@CaF<sub>2</sub> core/shell UCNCs; (<b>e</b>) α-NaLuF<sub>4</sub>:Yb<sup>3+</sup>/Ln<sup>3+</sup>@CaF<sub>2</sub> core/shell UCNCs. Particles in (c–e) were synthesized by the thermal decomposition method.</p> Full article ">Figure 4
<p>The X-ray diffraction patterns of the (a) α-NaLuF<sub>4</sub>:Yb<sup>3+</sup>/Ln<sup>3+</sup> NCs; (b) α-NaLuF<sub>4</sub>:Yb<sup>3+</sup>/Er<sup>3+</sup>@CaF<sub>2</sub> core/shell UCNCs; (c) α-NaLuF<sub>4</sub>:Yb<sup>3+</sup>/Ho<sup>3+</sup>@CaF<sub>2</sub> core/shell UCNCs; and (d) the α-NaLuF<sub>4</sub>:Yb<sup>3+</sup>/Tm<sup>3+</sup>@CaF<sub>2</sub> core/shell UCNCs, in reference to the standard diffraction patterns of the α-phase NaLuF<sub>4</sub> (JCPDS 27-0725) and cubic phase CaF<sub>2</sub> (JCPDS 02-1302).</p> Full article ">Figure 5
<p>The upconversion luminescence spectra under excitation at 976 nm using a fiber-coupled laser diode: (<b>a</b>) the α-NaLuF<sub>4</sub>:Yb<sup>3+</sup>/Er<sup>3+</sup> core and α-NaLuF<sub>4</sub>:Yb<sup>3+</sup>/Er<sup>3+</sup>@CaF<sub>2</sub> core/shell NPs; (<b>b</b>) the α-NaLuF<sub>4</sub>:Yb<sup>3+</sup>/Ho<sup>3+</sup> core and α-NaLuF<sub>4</sub>:Yb<sup>3+</sup>/Ho<sup>3+</sup>@CaF<sub>2</sub> core/shell NPs; (<b>c</b>) the α-NaLuF<sub>4</sub>:Yb<sup>3+</sup>/ Tm<sup>3+</sup> core and α-NaLuF<sub>4</sub>:Yb<sup>3+</sup>/Tm<sup>3+</sup>@CaF<sub>2</sub> core/shell NPs. The concentration of Ln<sup>3+</sup> in all samples was kept identical at about 0.5 mmol nanoparticles (i.e., nanoparticles formed by 0.5 mmol lanthanide precursors) per 10 mL cyclohexane.</p> Full article ">Figure 5 Cont.
<p>The upconversion luminescence spectra under excitation at 976 nm using a fiber-coupled laser diode: (<b>a</b>) the α-NaLuF<sub>4</sub>:Yb<sup>3+</sup>/Er<sup>3+</sup> core and α-NaLuF<sub>4</sub>:Yb<sup>3+</sup>/Er<sup>3+</sup>@CaF<sub>2</sub> core/shell NPs; (<b>b</b>) the α-NaLuF<sub>4</sub>:Yb<sup>3+</sup>/Ho<sup>3+</sup> core and α-NaLuF<sub>4</sub>:Yb<sup>3+</sup>/Ho<sup>3+</sup>@CaF<sub>2</sub> core/shell NPs; (<b>c</b>) the α-NaLuF<sub>4</sub>:Yb<sup>3+</sup>/ Tm<sup>3+</sup> core and α-NaLuF<sub>4</sub>:Yb<sup>3+</sup>/Tm<sup>3+</sup>@CaF<sub>2</sub> core/shell NPs. The concentration of Ln<sup>3+</sup> in all samples was kept identical at about 0.5 mmol nanoparticles (i.e., nanoparticles formed by 0.5 mmol lanthanide precursors) per 10 mL cyclohexane.</p> Full article ">Figure 6
<p>The energy level diagrams of Yb<sup>3+</sup>, Er<sup>3+</sup>, Tm<sup>3+</sup>, and Ho<sup>3+</sup> ions, showing the proposed upconversion mechanisms in the α-NaLuF<sub>4</sub>:Yb<sup>3+</sup>/Ln<sup>3+</sup>@CaF<sub>2</sub> (Ln = Er, Ho, or Tm) core/shell UCNCs.</p> Full article ">
1641 KiB  
Communication
{Ni4O4} Cluster Complex to Enhance the Reductive Photocurrent Response on Silicon Nanowire Photocathodes
by Yatin J. Mange, Soundarrajan Chandrasekaran, Nathan Hollingsworth, Nicolas H. Voelcker, Ivan P. Parkin, Thomas Nann and Thomas J. Macdonald
Nanomaterials 2017, 7(2), 33; https://doi.org/10.3390/nano7020033 - 6 Feb 2017
Cited by 2 | Viewed by 5153
Abstract
Metal organic {Ni4O4} clusters, known oxidation catalysts, have been shown to provide a valuable route in increasing the photocurrent response on silicon nanowire (SiNW) photocathodes. {Ni4O4} clusters have been paired with SiNWs to form a [...] Read more.
Metal organic {Ni4O4} clusters, known oxidation catalysts, have been shown to provide a valuable route in increasing the photocurrent response on silicon nanowire (SiNW) photocathodes. {Ni4O4} clusters have been paired with SiNWs to form a new photocathode composite for water splitting. Under AM1.5 conditions, the combination of {Ni4O4} clusters with SiNWs gave a current density of −16 mA/cm2, which corresponds to an increase in current density of 60% when compared to bare SiNWs. The composite electrode was fully characterised and shown to be an efficient and stable photocathode for water splitting. Full article
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Structure of <b>1</b> taken from the Cambridge Crystallographic Data Centre (CCDC). Solvate molecules, anion and all H atoms bonded to C omitted for clarity. Central {Ni<sub>4</sub>O<sub>4</sub>} cubane unit bonds highlighted in green.</p> Full article ">Figure 2
<p>SEM images (<b>a</b>,<b>b</b>) top and cross section view of bare SiNWs. Inset in <a href="#nanomaterials-07-00033-f001" class="html-fig">Figure 1</a><b>a</b> represents islands of SiNWs; (<b>c</b>,<b>d</b>) top and cross section view of SiNWs coated with {Ni<sub>4</sub>O<sub>4</sub>} clusters.</p> Full article ">Figure 3
<p>Photocurrent measurements showing current density as a function of time for (<b>a</b>) bare SiNWs and (<b>b</b>) SiNWs + {Ni<sub>4</sub>O<sub>4</sub>} clusters.</p> Full article ">Figure 4
<p>Current density measurement of SiNWs + {Ni<sub>4</sub>O<sub>4</sub>} clusters catalyst in 0.1 M H<sub>2</sub>SO<sub>4</sub> at a bias potential of −500 mV over 5 h.</p> Full article ">
0 pages, 5669 KiB  
Article
RETRACTED: Synthesis, Optical and Structural Properties of Copper Sulfide Nanocrystals from Single Molecule Precursors
by Peter A. Ajibade and Nandipha L. Botha
Nanomaterials 2017, 7(2), 32; https://doi.org/10.3390/nano7020032 - 4 Feb 2017
Cited by 25 | Viewed by 6947 | Retraction
Abstract
We report the synthesis and structural studies of copper sulfide nanocrystals from copper (II) dithiocarbamate single molecule precursors. The precursors were thermolysed in hexadecylamine (HDA) to prepare HDA-capped CuS nanocrystals. The optical properties of the nanocrystals studied using UV–visible and photoluminescence spectroscopy showed [...] Read more.
We report the synthesis and structural studies of copper sulfide nanocrystals from copper (II) dithiocarbamate single molecule precursors. The precursors were thermolysed in hexadecylamine (HDA) to prepare HDA-capped CuS nanocrystals. The optical properties of the nanocrystals studied using UV–visible and photoluminescence spectroscopy showed absorption band edges at 287 nm that are blue shifted, and the photoluminescence spectra show emission curves that are red-shifted with respect to the absorption band edges. These shifts are as a result of the small crystallite sizes of the nanoparticles leading to quantum size effects. The structural studies were carried out using powder X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and atomic force microscopy. The XRD patterns indicates that the CuS nanocrystals are in hexagonal covellite crystalline phases with estimated particles sizes of 17.3–18.6 nm. The TEM images showed particles with almost spherical or rod shapes, with average crystallite sizes of 3–9.8 nm. SEM images showed morphology with ball-like microspheres on the surfaces, and EDS spectra confirmed the presence of CuS nanoparticles. Full article
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<p>Absorption spectra of copper (II)-<span class="html-italic">N</span>-phenyl dithiocarbamate complex (<b>CuS1</b>), copper (II)-<span class="html-italic">N</span>,<span class="html-italic">N</span>-ethylphenyldithiocarbamate (<b>CuS2</b>), and copper (II)-morpholinedithiocarbamate (<b>CuS3</b>) nanoparticles.</p> Full article ">Figure 1 Cont.
<p>Absorption spectra of copper (II)-<span class="html-italic">N</span>-phenyl dithiocarbamate complex (<b>CuS1</b>), copper (II)-<span class="html-italic">N</span>,<span class="html-italic">N</span>-ethylphenyldithiocarbamate (<b>CuS2</b>), and copper (II)-morpholinedithiocarbamate (<b>CuS3</b>) nanoparticles.</p> Full article ">Figure 2
<p>Emission spectra of <b>CuS1</b>, <b>CuS2</b>, and <b>CuS3</b> nanoparticles.</p> Full article ">Figure 3
<p>Powder X-ray diffraction (XRD) patterns of <b>CuS1</b> (<b>A</b>), <b>CuS2</b> (<b>B</b>), and <b>CuS3</b> (<b>C</b>) nanoparticles * hexadecylamine (HDA).</p> Full article ">Figure 3 Cont.
<p>Powder X-ray diffraction (XRD) patterns of <b>CuS1</b> (<b>A</b>), <b>CuS2</b> (<b>B</b>), and <b>CuS3</b> (<b>C</b>) nanoparticles * hexadecylamine (HDA).</p> Full article ">Figure 4
<p>Transmission electron microscopy (TEM) images of <b>CuS1</b> (<b>A</b>), <b>CuS2</b> (<b>B</b>), and <b>CuS3</b> (<b>C</b>) nanoparticles.</p> Full article ">Figure 5
<p>Scanning electron microscopy (SEM) images of <b>CuS1</b>, <b>CuS2</b>, and <b>CuS3</b> nanoparticles.</p> Full article ">Figure 6
<p>Atomic force microscopy (AFM) surface roughness (<b>A</b>) and 3D topographical images (<b>B</b>) of <b>CuS1</b> nanoparticles.</p> Full article ">Figure 7
<p>AFM surface roughness (<b>A</b>) and 3D topographical images (<b>B</b>) of <b>CuS2</b> nanoparticles.</p> Full article ">Figure 7 Cont.
<p>AFM surface roughness (<b>A</b>) and 3D topographical images (<b>B</b>) of <b>CuS2</b> nanoparticles.</p> Full article ">Figure 8
<p>AFM surface roughness (<b>A</b>) and 3D topographical images (<b>B</b>) of CuS3 nanoparticles.</p> Full article ">
1578 KiB  
Article
Formation of Platinum Catalyst on Carbon Black Using an In‐Liquid Plasma Method for Fuel Cells
by Yoshiyuki Show and Yutaro Ueno
Nanomaterials 2017, 7(2), 31; https://doi.org/10.3390/nano7020031 - 31 Jan 2017
Cited by 19 | Viewed by 5919
Abstract
Platinum (Pt) catalyst was formed on the surface of carbon black using an in‐liquid plasma method. The formed Pt catalyst showed the average particle size of 4.1 nm. This Pt catalyst was applied to a polymer electrolyte membrane fuel cell (PEMFC). The PEMFC [...] Read more.
Platinum (Pt) catalyst was formed on the surface of carbon black using an in‐liquid plasma method. The formed Pt catalyst showed the average particle size of 4.1 nm. This Pt catalyst was applied to a polymer electrolyte membrane fuel cell (PEMFC). The PEMFC showed an open voltage of 0.85 V and a maximum output power density of 216 mW/cm2. Full article
(This article belongs to the Special Issue Nanomaterials Based Fuel Cells and Supercapacitors)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Photograph of vessel used for the in-liquid plasma process.</p> Full article ">Figure 2
<p>Transmission electron microscope (TEM) images of carbon black (<b>a</b>) before; and (<b>b</b>) after the in-liquid plasma process was carried out for 20 min.</p> Full article ">Figure 3
<p>Histogram of the size distributions of the Pt particles on the carbon black.</p> Full article ">Figure 4
<p>Cyclic voltammogram observed for the fuel cell, which was fabricated with the carbon black after the in-liquid plasma process was carried out for 20 min.</p> Full article ">Figure 5
<p>Dependence of the output current on (<b>a</b>) the output voltage; and (<b>b</b>) electric power for fuel cells fabricated with the Pt catalyst formed on carbon black using in-liquid plasma at various processing times.</p> Full article ">Figure 6
<p>The cole–cole plots for the impedance measurements of the fuel cells fabricated using the Pt catalyst formed on the carbon black by in-liquid plasma at various processing times.</p> Full article ">Figure 7
<p>The equivalent circuit for the internal impedance of a fuel cell, which was used for estimating the series resistance (R<sub>s</sub>) and parallel resistance (R<sub>p</sub>).</p> Full article ">Figure 8
<p>The dependence of the in-liquid plasma processing time on (<b>a</b>) the weight of the loaded Pt; (<b>b</b>) the electrochemically active surface area (EASA) of the Pt catalyst per unit area (1 × 1 cm<sup>2</sup>) of the cathode and electrode; (<b>c</b>) the parallel resistance (R<sub>p</sub>) and series resistance (R<sub>s</sub>); and (<b>d</b>) the maximum output power density for the fuel cells.</p> Full article ">
4286 KiB  
Article
A High Power, Frequency Tunable Colloidal Quantum Dot (CdSe/ZnS) Laser
by Saradh Prasad, Hanan Saleh AlHesseny, Mohamad S. AlSalhi, Durairaj Devaraj and Vadivel Masilamai
Nanomaterials 2017, 7(2), 29; https://doi.org/10.3390/nano7020029 - 30 Jan 2017
Cited by 10 | Viewed by 5889
Abstract
Tunable lasers are essential for medical, engineering and basic science research studies. Most conventional solid-state lasers are capable of producing a few million laser shots, but limited to specific wavelengths, which are bulky and very expensive. Dye lasers are continuously tunable, but exhibit [...] Read more.
Tunable lasers are essential for medical, engineering and basic science research studies. Most conventional solid-state lasers are capable of producing a few million laser shots, but limited to specific wavelengths, which are bulky and very expensive. Dye lasers are continuously tunable, but exhibit very poor chemical stability. As new tunable, efficient lasers are always in demand, one such laser is designed with various sized CdSe/ZnS quantum dots. They were used as a colloid in tetrahydrofuran to produce a fluorescent broadband emission from 520 nm to 630 nm. The second (532 nm) and/or third harmonic (355 nm) of the Nd:YAG laser (10 ns, 10 Hz) were used together as the pump source. In this study, different sized quantum dots were independently optically pumped to produce amplified spontaneous emission (ASE) with 4 nm to 7 nm of full width at half-maximum (FWHM), when the pump power and focusing were carefully optimized. The beam was directional with a 7 mrad divergence. Subsequently, these quantum dots were combined together, and the solution was placed in a resonator cavity to obtain a laser with a spectral width of 1 nm and tunable from 510 to 630 nm, with a conversion efficiency of about 0.1%. Full article
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<p>The absorption spectra for different sized quantum dots at a concentration of 2 mg in 5 mL of THF.</p> Full article ">Figure 2
<p>The photoluminescence (PL) for the different sized quantum dots at a concentration of 2 mg in 5 mL of THF.</p> Full article ">Figure 3
<p>(<b>a</b>) The spectral profile of the quantum dots (QD 1) at a concentration of 2 mg in 5 mL of THF; (<b>b</b>) The temporal profile of the quantum dots (QD 1) at a concentration of 20 mg in 5 mL of THF; (<b>c</b>) Depicts the three dimensional (3D) temporal and spectral profile for another quantum dot (QDs 5, 609 nm) at 24 mg in 5 mL of THF. To differentiate one time frame from other, difference color line are used, each frame represent 0.25 ns.</p> Full article ">Figure 3 Cont.
<p>(<b>a</b>) The spectral profile of the quantum dots (QD 1) at a concentration of 2 mg in 5 mL of THF; (<b>b</b>) The temporal profile of the quantum dots (QD 1) at a concentration of 20 mg in 5 mL of THF; (<b>c</b>) Depicts the three dimensional (3D) temporal and spectral profile for another quantum dot (QDs 5, 609 nm) at 24 mg in 5 mL of THF. To differentiate one time frame from other, difference color line are used, each frame represent 0.25 ns.</p> Full article ">Figure 4
<p>The amplified spontaneous emission (ASE) spectra profile of all quantum dots (QD 1 to QD 6) for a concentration ranging between 20 and 30 mg in 5 mL THF.</p> Full article ">Figure 5
<p>The energy transfer cross-section between QDs and poly (9, 9-dioctylfluorenyl-2,7-diyl) (PFO) and poly [(9,9-dioctylfluorenyl-2,7-diyl (PFO) and poly [2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV).</p> Full article ">Figure 6
<p>The energy transfer from PFO and MEH-PPV to QDs; here, the ASE efficiency was improved at least three-fold from the prior condition to the energy transfer. The performance of QD 4, QD 5, and QDs 6 increased notably after the addition of MEH-PPV.</p> Full article ">Figure 7
<p>The laser set-up.</p> Full article ">Figure 8
<p>Narrow laser spectra and Laser Induced Fluorescence (LIF) of the solution.</p> Full article ">Figure 9
<p>The molecular structures of (<b>a</b>) PFO and (<b>b</b>) MEH-PPV.</p> Full article ">Figure 9 Cont.
<p>The molecular structures of (<b>a</b>) PFO and (<b>b</b>) MEH-PPV.</p> Full article ">
1192 KiB  
Brief Report
Oscillating Magnet Array−Based Nanomagnetic Gene Transfection: A Valuable Tool for Molecular Neurobiology Studies
by Mahendran Subramanian, Aimee-Jayne Tyler, Eva Maria Luther, Elena Di Daniel, Jenson Lim and Jon Dobson
Nanomaterials 2017, 7(2), 28; https://doi.org/10.3390/nano7020028 - 29 Jan 2017
Cited by 5 | Viewed by 6511
Abstract
To develop treatments for neurodegenerative disorders, it is critical to understand the biology and function of neurons in both normal and diseased states. Molecular studies of neurons involve the delivery of small biomolecules into cultured neurons via transfection to study genetic variants. However, [...] Read more.
To develop treatments for neurodegenerative disorders, it is critical to understand the biology and function of neurons in both normal and diseased states. Molecular studies of neurons involve the delivery of small biomolecules into cultured neurons via transfection to study genetic variants. However, as cultured primary neurons are sensitive to temperature change, stress, and shifts in pH, these factors make biomolecule delivery difficult, particularly non-viral delivery. Herein we used oscillating nanomagnetic gene transfection to successfully transfect SH-SY5Y cells as well as primary hippocampal and cortical neurons on different days in vitro. This novel technique has been used to effectively deliver genetic material into various cell types, resulting in high transfection efficiency and viability. From these observations and other related studies, we suggest that oscillating nanomagnetic gene transfection is an effective method for gene delivery into hard-to-transfect neuronal cell types. Full article
(This article belongs to the Special Issue Functional Magnetic Nanoparticles in Nanomedicine)
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Figure 1
<p>Oscillating magnet array−based nanomagnetic gene transfection experimental setup. (<b>A</b>) Representation of a 96-well oscillating magnet array–based nanomagnetic transfection setup using NdFeB magnetic array; (<b>B</b>) Dimensions of the permanent magnets and magnetostatic (vector-potential) algorithm based magnetic field density |B| distribution (T) contour plot for the NdFeB magnetic array.</p> Full article ">Figure 2
<p>Magneto-static (vector potential) algorithm–based numerical calculations: (<b>A</b>) 2D plot of the magnetic field for <span class="html-italic">x</span> axis (marked in red line horizontal above the magnet array in <a href="#nanomaterials-07-00028-f001" class="html-fig">Figure 1</a>B); (<b>B</b>) 2D plot of the magnetic field for <span class="html-italic">y</span> axis (marked in red line vertical above the magnet array in <a href="#nanomaterials-07-00028-f001" class="html-fig">Figure 1</a>B).</p> Full article ">Figure 3
<p>Higher gene expression in undifferentiated SH-SY5Y cells. (<b>A</b>) Fluorescent images of GFP-expressing SH-SY5Y cells transfected using (I) an oscillating magnet array (Frequency = 2 Hz; Displacement = 0.2 mm) or (II) a cationic lipid–based reagent; (<b>B</b>) Bar chart showing the percentage of GFP-expressing cells 48 h after transfection with different oscillating magnet array settings. FACS data shown are the mean ± SD of (<span class="html-italic">n</span> = 3), respectively.</p> Full article ">Figure 4
<p>Neuron-specific gene delivery methods in primary hippocampal cells. Images of Synap 1 plasmid expressing primary neurons (2 × 10<sup>4</sup> cells/well). Fluorescent and phase contrast images of transfected DIV 7 (<b>A</b>,<b>D</b>), DIV 14 (<b>B</b>,<b>E</b>) and DIV 21 (<b>C</b>,<b>F</b>) mature neurons using an oscillating magnet array (Frequency = 2 Hz; Displacement = 0.2 mm), imaged at 96 h (<b>A</b>,<b>D</b>) or 48 h (<b>B</b>,<b>C</b>,<b>E</b>,<b>F</b>) post transfection.</p> Full article ">Figure 5
<p>Gene delivery by oscillating nanomagnetic gene transfection in primary cortical neurons. Images of pmaxGFP plasmid expressed in primary neurons using fluorescence microscopy and its corresponding Hoechst 33,342 stained counterpart of transfected DIV 1 (<b>A</b>,<b>C</b>) and DIV 5 (<b>B</b>,<b>D</b>) mature neurons were taken 48 h post transfection.</p> Full article ">
310 KiB  
Review
Modified Continuum Mechanics Modeling on Size-Dependent Properties of Piezoelectric Nanomaterials: A Review
by Zhi Yan and Liying Jiang
Nanomaterials 2017, 7(2), 27; https://doi.org/10.3390/nano7020027 - 26 Jan 2017
Cited by 60 | Viewed by 8322
Abstract
Piezoelectric nanomaterials (PNs) are attractive for applications including sensing, actuating, energy harvesting, among others in nano-electro-mechanical-systems (NEMS) because of their excellent electromechanical coupling, mechanical and physical properties. However, the properties of PNs do not coincide with their bulk counterparts and depend on the [...] Read more.
Piezoelectric nanomaterials (PNs) are attractive for applications including sensing, actuating, energy harvesting, among others in nano-electro-mechanical-systems (NEMS) because of their excellent electromechanical coupling, mechanical and physical properties. However, the properties of PNs do not coincide with their bulk counterparts and depend on the particular size. A large amount of efforts have been devoted to studying the size-dependent properties of PNs by using experimental characterization, atomistic simulation and continuum mechanics modeling with the consideration of the scale features of the nanomaterials. This paper reviews the recent progresses and achievements in the research on the continuum mechanics modeling of the size-dependent mechanical and physical properties of PNs. We start from the fundamentals of the modified continuum mechanics models for PNs, including the theories of surface piezoelectricity, flexoelectricity and non-local piezoelectricity, with the introduction of the modified piezoelectric beam and plate models particularly for nanostructured piezoelectric materials with certain configurations. Then, we give a review on the investigation of the size-dependent properties of PNs by using the modified continuum mechanics models, such as the electromechanical coupling, bending, vibration, buckling, wave propagation and dynamic characteristics. Finally, analytical modeling and analysis of nanoscale actuators and energy harvesters based on piezoelectric nanostructures are presented. Full article
(This article belongs to the Special Issue Piezoelectric Nanomaterials)
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<p>Schematic of (<b>a</b>) a piezoelectric nanobeam; and (<b>b</b>) a piezoelectric nanoplate with surface effects.</p> Full article ">
3411 KiB  
Article
Light Emission Intensities of Luminescent Y2O3:Eu and Gd2O3:Eu Particles of Various Sizes
by Jens Adam, Wilhelm Metzger, Marcus Koch, Peter Rogin, Toon Coenen, Jennifer S. Atchison and Peter König
Nanomaterials 2017, 7(2), 26; https://doi.org/10.3390/nano7020026 - 25 Jan 2017
Cited by 44 | Viewed by 7394
Abstract
There is great technological interest in elucidating the effect of particle size on the luminescence efficiency of doped rare earth oxides. This study demonstrates unambiguously that there is a size effect and that it is not dependent on the calcination temperature. The Y [...] Read more.
There is great technological interest in elucidating the effect of particle size on the luminescence efficiency of doped rare earth oxides. This study demonstrates unambiguously that there is a size effect and that it is not dependent on the calcination temperature. The Y2O3:Eu and Gd2O3:Eu particles used in this study were synthesized using wet chemistry to produce particles ranging in size between 7 nm and 326 nm and a commercially available phosphor. These particles were characterized using three excitation methods: UV light at 250 nm wavelength, electron beam at 10 kV, and X-rays generated at 100 kV. Regardless of the excitation source, it was found that with increasing particle diameter there is an increase in emitted light. Furthermore, dense particles emit more light than porous particles. These results can be explained by considering the larger surface area to volume ratio of the smallest particles and increased internal surface area of the pores found in the large particles. For the small particles, the additional surface area hosts adsorbates that lead to non-radiative recombination, and in the porous particles, the pore walls can quench fluorescence. This trend is valid across calcination temperatures and is evident when comparing particles from the same calcination temperature. Full article
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>(<b>a</b>) Schematic structure of the X-ray measuring station for the spatially resolved determination of the X-ray excited light yield of scintillating materials; (<b>b</b>) Sample holder made of highly reflective Teflon containing a 0.5 mm thick scintillating powder layer (see the text for further details).</p> Full article ">Figure 2
<p>Average particle size <span class="html-italic">d</span><sub>SSA</sub> after calcination. (<b>a</b>) Peroxidic Precipitation (PP) particles as a function of the calcination temperature; (<b>b</b>) Urea based homogeneous precipitation (UBHP) particles after calcination at 850 °C as a function of the concentration ratio <span class="html-italic">c</span><sub>urea</sub>/<span class="html-italic">c</span><sub>metals</sub> and of the reaction medium (pure H<sub>2</sub>O for points connected with the dotted line; others: H<sub>2</sub>O plus EG = ethylene glycol, B = 1-butanol, P = 2-propanol, see <a href="#nanomaterials-07-00026-t001" class="html-table">Table 1</a>. At <span class="html-italic">c</span><sub>urea</sub>/<span class="html-italic">c</span><sub>metals</sub> = 63 there are two overlapping data points).</p> Full article ">Figure 3
<p>Transmission electron microscope (TEM) images of the PP particles, (<b>a</b>) Y<sub>2</sub>O<sub>3</sub>:Eu calcined at 450 °C; (<b>b</b>) Gd<sub>2</sub>O<sub>3</sub>:Eu calcined at 450 °C; (<b>c</b>) Y<sub>2</sub>O<sub>3</sub>:Eu calcined at 1000 °C; (<b>d</b>) Gd<sub>2</sub>O<sub>3</sub>:Eu calcined at 1000 °C.</p> Full article ">Figure 4
<p>Environmental scanning electron microscope (ESEM) images [taken with the large field detector, exception: image (f)] of UBHP Gd<sub>2</sub>O<sub>3</sub>:Eu particles calcined at 850 °C; (<b>a</b>) NS141-850 (<span class="html-italic">d</span><sub>SSA</sub> = 86 nm); (<b>b</b>) NS130-850 (<span class="html-italic">d</span><sub>SSA</sub> = 147 nm); (<b>c</b>) NS126-850 (<span class="html-italic">d</span><sub>SSA</sub> = 244 nm); (<b>d</b>) NS133-850 (<span class="html-italic">d</span><sub>SSA</sub> = 326 nm); (<b>e</b>) NS133-850—view into a trench cut by Focused Ion Beam (FIB) into the pellet pressed for prior cathodoluminescence (CL) examination; (<b>f</b>) NS133-850—particle image, taken with the back-scattered electron (BSE) detector.</p> Full article ">Figure 5
<p>Particle size <span class="html-italic">d</span><sub>SEM</sub> and crystallite size <span class="html-italic">d</span><sub>XRD</sub> of the calcined UBHP particles, as a function of the size information <span class="html-italic">d</span><sub>SSA</sub>.</p> Full article ">Figure 6
<p>Luminescence spectra of the Gd<sub>2</sub>O<sub>3</sub>:Eu particles (no indication) and of the Y<sub>2</sub>O<sub>3</sub>:Eu particles (where indicated), (<b>a</b>) fluorescence excitation spectra (cut peak around 306 nm = 1st order diffraction from monochromator, i.e., spectrometer artefact); (<b>b</b>) fluorescence emission spectra; (<b>c</b>) cathodoluminescence emission spectra (taken from 577 to 636 nm).</p> Full article ">Figure 7
<p>Relative light yield of the Gd<sub>2</sub>O<sub>3</sub>:Eu particles (no indication) and of the Y<sub>2</sub>O<sub>3</sub>:Eu particles (where indicated), depicted in dependence of the particle size <span class="html-italic">d</span><sub>SSA</sub>. Particles with sizes up to 74 nm are from the PP synthesis, larger particles with data points in the ovals are from the UBHP synthesis. (<b>a</b>) For excitation with 250 nm UV light (second ordinate giving the absolute QY values); (<b>b</b>) for excitation with e-beam (cathodoluminescence); (<b>c</b>) for excitation with X-ray.</p> Full article ">
3307 KiB  
Article
Design and Synthesis of TiO2 Hollow Spheres with Spatially Separated Dual Cocatalysts for Efficient Photocatalytic Hydrogen Production
by Qianqian Jiang, Li Li, Jinhong Bi, Shijing Liang and Minghua Liu
Nanomaterials 2017, 7(2), 24; https://doi.org/10.3390/nano7020024 - 25 Jan 2017
Cited by 26 | Viewed by 6822
Abstract
TiO2 hollow spheres modified with spatially separated Ag species and RuO2 cocatalysts have been prepared via an alkoxide hydrolysis–precipitation method and a facile impregnation method. High-resolution transmission electron microscopy studies indicate that Ag species and RuO2 co-located on the inner [...] Read more.
TiO2 hollow spheres modified with spatially separated Ag species and RuO2 cocatalysts have been prepared via an alkoxide hydrolysis–precipitation method and a facile impregnation method. High-resolution transmission electron microscopy studies indicate that Ag species and RuO2 co-located on the inner and outer surface of TiO2 hollow spheres, respectively. The resultant catalysts show significantly enhanced activity in photocatalytic hydrogen production under simulated sunlight attributed to spatially separated Ag species and RuO2 cocatalysts on TiO2 hollow spheres, which results in the efficient separation and transportation of photogenerated charge carriers. Full article
(This article belongs to the Special Issue Nanoscale in Photocatalysis)
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<p>X-ray diffraction (XRD) patterns of TiO<sub>2</sub> hollow spheres (THS) loaded by the cocatalysts with different spatial dispersion: (<b>a</b>) THS; (<b>b</b>) Ag-loaded THS on the inner surface (Ag-I-THS); (<b>c</b>) RuO<sub>2</sub>-loaded THS on the outer surface (RuO<sub>2</sub>-O-THS); (<b>d</b>) Ag- and RuO<sub>2</sub>-co-loaded THS on the inner surface and outer surface (Ag-I-RuO<sub>2</sub>-O-THS); (<b>e</b>) RuO<sub>2</sub>- and Ag-co-loaded THS on the inner surface and outer surface (RuO<sub>2</sub>-I-Ag-O-THS).</p> Full article ">Figure 2
<p>N<sub>2</sub> adsorption-desorption isotherms of THS and Ag-I-RuO<sub>2</sub>-O-THS.</p> Full article ">Figure 3
<p>(<b>a</b>) Transmission electron microscopy (TEM) and (<b>b</b>) High resolution transmission electron microscopy (HRTEM) images of Ag-I-RuO<sub>2</sub>-O-THS.</p> Full article ">Figure 4
<p>X-ray photoelectron spectroscopy (XPS) spectra of Ag-I-RuO<sub>2</sub>-O-THS: (<b>a</b>) C 1s and Ru 3d; (<b>b</b>) Ag 3d; (<b>c</b>) O 1s; (<b>d</b>) Ti 2p.</p> Full article ">Figure 5
<p>Ultraviolet-visible diffuse reflectance spectra (UV-Vis DRS) of THS loaded by the cocatalysts with different spatial dispersion.</p> Full article ">Figure 6
<p>Photocatalytic activities of H<sub>2</sub> evolution on THS loaded by the cocatalysts with different spatial dispersion.</p> Full article ">Figure 7
<p>Stability of Ag-I-RuO<sub>2</sub>-O-THS during prolonged photocatalytic operation.</p> Full article ">Scheme 1
<p>Processes involved in the formation of dual cocatalysts co-loading on the TiO<sub>2</sub> hollow spheres (THS).</p> Full article ">Scheme 2
<p>The photocatalytic hydrogen production on Ag-I-RuO<sub>2</sub>-O-THS.</p> Full article ">
3719 KiB  
Article
One-Step Reduction and Surface Modification of Graphene Oxide by 3-Hydroxy-2-Naphthoic Acid Hydrazide and Its Polypropylene Nanocomposites
by Xiang-Nan Xu, Xiao-Na Guan, Hui-Hua Zhou and Yue-Feng Zhu
Nanomaterials 2017, 7(2), 25; https://doi.org/10.3390/nano7020025 - 24 Jan 2017
Cited by 13 | Viewed by 6310
Abstract
3-Hydroxy-2-naphthoic acid hydrazide (HNH), a new reductant and modifier, was applied to reduce and modify graphene oxide (GO) in a one-step process. The obtained HNH reduced graphene oxide (HNH-rGO) was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), Raman spectroscopy, X-ray photoelectron [...] Read more.
3-Hydroxy-2-naphthoic acid hydrazide (HNH), a new reductant and modifier, was applied to reduce and modify graphene oxide (GO) in a one-step process. The obtained HNH reduced graphene oxide (HNH-rGO) was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), Raman spectroscopy, X-ray photoelectron spectroscopic (XPS) and Fourier transform infrared spectra (FTIR). The results demonstrated that GO was successfully reduced to graphene and the surface of HNH-rGO was grafted with HNH. The interlayer space was increased from 0.751 nm to 1.921 nm, and its agglomeration was much more attenuated compared with GO. HNH-rGO/polypropylene and graphene/polypropylene composites were synthesized through melt-blending method. The viscosity was enhanced with increased addition of graphene and surface modified graphene demonstrated stronger rheological behavior improving effect than the untreated graphene. Full article
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<p>Chemical structure of 3-hydroxy-2-naphthoic acid hydrazide (HNH).</p> Full article ">Figure 2
<p>Synthesis reaction of HNH modified reduced graphene oxide (HNH-rGO) from graphene oxide (GO).</p> Full article ">Figure 3
<p>The X-ray diffraction (XRD) patterns of GO (<b>a</b>) and HNH-rGO (<b>b</b>).</p> Full article ">Figure 4
<p>The scanning electron microscope (SEM) images of GO (<b>a</b>) and HNH-rGO (<b>b</b>).</p> Full article ">Figure 5
<p>The Raman spectroscopy of G, GO and HNH-rGO (<b>a</b>) and the 2D peak of HNH-rGO (<b>b</b>).</p> Full article ">Figure 6
<p>The Fourier transform infrared (FTIR) spectra of GO and HNH-rGO.</p> Full article ">Figure 7
<p>The X-ray photoelectron spectroscopic (XPS) spectra of GO and HNH-rGO: all elements survey scan of GO (<b>a</b>); HNH-rGO (<b>b</b>); C 1s survey scan of GO (<b>c</b>) and HNH-rGO (<b>d</b>).</p> Full article ">Figure 7 Cont.
<p>The X-ray photoelectron spectroscopic (XPS) spectra of GO and HNH-rGO: all elements survey scan of GO (<b>a</b>); HNH-rGO (<b>b</b>); C 1s survey scan of GO (<b>c</b>) and HNH-rGO (<b>d</b>).</p> Full article ">Figure 8
<p>Rheology behavior of 1%, 2%, 5% graphene/PP composites (<b>a</b>); 1% graphene/PP composites and HNH-rGO/PP composites (<b>b</b>).</p> Full article ">
7468 KiB  
Article
Linear and Nonlinear Rheology Combined with Dielectric Spectroscopy of Hybrid Polymer Nanocomposites for Semiconductive Applications
by Roland Kádár, Mahdi Abbasi, Roxana Figuli, Mikael Rigdahl and Manfred Wilhelm
Nanomaterials 2017, 7(2), 23; https://doi.org/10.3390/nano7020023 - 24 Jan 2017
Cited by 36 | Viewed by 7899
Abstract
The linear and nonlinear oscillatory shear, extensional and combined rheology-dielectric spectroscopy of hybrid polymer nanocomposites for semiconductive applications were investigated in this study. The main focus was the influence of processing conditions on percolated poly(ethylene-butyl acrylate) (EBA) nanocomposite hybrids containing graphite nanoplatelets (GnP) [...] Read more.
The linear and nonlinear oscillatory shear, extensional and combined rheology-dielectric spectroscopy of hybrid polymer nanocomposites for semiconductive applications were investigated in this study. The main focus was the influence of processing conditions on percolated poly(ethylene-butyl acrylate) (EBA) nanocomposite hybrids containing graphite nanoplatelets (GnP) and carbon black (CB). The rheological response of the samples was interpreted in terms of dispersion properties, filler distortion from processing, filler percolation, as well as the filler orientation and distribution dynamics inside the matrix. Evidence of the influence of dispersion properties was found in linear viscoelastic dynamic frequency sweeps, while the percolation of the nanocomposites was detected in nonlinearities developed in dynamic strain sweeps. Using extensional rheology, hybrid samples with better dispersion properties lead to a more pronounced strain hardening behavior, while samples with a higher volume percentage of fillers caused a drastic reduction in strain hardening. The rheo-dielectric time-dependent response showed that in the case of nanocomposites containing only GnP, the orientation dynamics leads to non-conductive samples. However, in the case of hybrids, the orientation of the GnP could be offset by the dispersing of the CB to bridge the nanoplatelets. The results were interpreted in the framework of a dual PE-BA model, where the fillers would be concentrated mainly in the BA regions. Furthermore, better dispersed hybrids obtained using mixing screws at the expense of filler distortion via extrusion processing history were emphasized through the rheo-dielectric tests. Full article
(This article belongs to the Special Issue Multifunctional Polymer-Based Nanocomposites)
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Figure 1

Figure 1
<p>The screw types used to control the deformation history of the nanocomposites analyzed using a Brabender 19/25D single-screw extruder: (<b>a</b>) C-screw, conventional geometry with 2:1 compression ratio; and (<b>b</b>) M-screw, distributive mixing screw composed of a Maillefer region a Saxton mixing element.</p> Full article ">Figure 2
<p>Generic principle of Fourier transform rheology showing time-dependent linear and nonlinear stress material response to a sinusoidal strain input and corresponding Fourier transform of the output signal showing the presence of higher harmonics in the nonlinear case.</p> Full article ">Figure 3
<p>Dynamic strain sweep (<math display="inline"> <semantics> <mrow> <mi mathvariant="sans-serif">ω</mi> <mo>=</mo> <mn>5</mn> </mrow> </semantics> </math> rad/s) comparing the dynamic moduli, <math display="inline"> <semantics> <msup> <mi>G</mi> <mo>′</mo> </msup> </semantics> </math> and <math display="inline"> <semantics> <msup> <mi>G</mi> <mrow> <mo>′</mo> <mo>′</mo> </mrow> </msup> </semantics> </math>, and the relative first higher harmonic, <math display="inline"> <semantics> <msub> <mi>I</mi> <mrow> <mn>3</mn> <mo>/</mo> <mn>1</mn> </mrow> </msub> </semantics> </math>, for poly(ethylene-butyl acrylate) (EBA) at 160 °C.</p> Full article ">Figure 4
<p>Simultaneous rheo-dielectric measurements performed to characterize the EBA nanocomposites. (<b>a</b>) Diagram of the combined rheometer and dielectric analyzer for determining the raw stress data and the dielectric spectra in situ. (<b>b</b>) Image of the rheo-dielectric geometries.</p> Full article ">Figure 5
<p>Dynamic frequency sweep measurements in the linear viscoelastic regime of the samples investigated, prepared using (<b>a</b>) the conventional screw, C, and (<b>b</b>) the distributive mixing screw, M. In both diagrams, the EBA matrix and EBA-GnP are plotted as references.</p> Full article ">Figure 6
<p>Strain amplitude dependence of the third relative higher harmonic, <math display="inline"> <semantics> <msub> <mi>I</mi> <mrow> <mn>3</mn> <mo>/</mo> <mn>1</mn> </mrow> </msub> </semantics> </math>, at various angular frequencies for: (<b>a</b>) EBA, (<b>b</b>) EBA-GnP, (<b>c</b>) 160C100 and (<b>d</b>) 160M100.</p> Full article ">Figure 7
<p>Extensional measurements (symbols) and the MSF theory predictions (solid lines) for (<b>a</b>) EBA, (<b>b</b>) EBA-GnP(1), (<b>c</b>) EBA-GnP(2), (<b>d</b>) 180C50 (<b>e</b>) 160M100 and (<b>f</b>) 160C100. The EBA-GnP(2) contains 9.5 vol% of GnP and was analyzed in order to test the limits of the strain hardening behavior. The dashed line, LVE, represents the linear viscoelastic envelope.</p> Full article ">Figure 8
<p>Transient development of the dynamic moduli and the <span class="html-italic">Q</span>-parameter in SAOS, <math display="inline"> <semantics> <mrow> <mi mathvariant="sans-serif">γ</mi> <mo>=</mo> <mn>1</mn> </mrow> </semantics> </math>% and <math display="inline"> <semantics> <mrow> <mi mathvariant="sans-serif">ω</mi> <mo>=</mo> <mn>0</mn> <mo>.</mo> <mn>5</mn> </mrow> </semantics> </math> rad/s: (<b>a</b>) 160C100 and (<b>b</b>) 160M100. All measurements were performed at 160 °C.</p> Full article ">Figure 9
<p>Transient development of the dynamic moduli and the <span class="html-italic">Q</span>-parameter in LAOS, <math display="inline"> <semantics> <mrow> <mi mathvariant="sans-serif">γ</mi> <mo>=</mo> <mn>100</mn> </mrow> </semantics> </math>% and <math display="inline"> <semantics> <mrow> <mi mathvariant="sans-serif">ω</mi> <mo>=</mo> <mn>1</mn> </mrow> </semantics> </math> rad/s, for (<b>a</b>) EBA-GnP, (<b>b</b>) 160C100, (<b>c</b>) 180C50 and (<b>d</b>) 180M100. All measurements were performed at 160 °C.</p> Full article ">Figure 10
<p>Transient development of the dielectric loss, <math display="inline"> <semantics> <msup> <mi mathvariant="sans-serif">ϵ</mi> <mrow> <mo>′</mo> <mo>′</mo> </mrow> </msup> </semantics> </math>, spectra for: (<b>a</b>) EBA-GnP, (<b>b</b>) 160C50, (<b>c</b>) 180C50 and (<b>d</b>) 180M100.</p> Full article ">Figure 11
<p>Interpretation of the dynamic behavior of the hybrid nanocomposites studied in the nonlinear viscoelastic regime, based on the model of Leblanc and Jäger [<a href="#B13-nanomaterials-07-00023" class="html-bibr">13</a>].</p> Full article ">Figure 12
<p>Electrical conductivity as the plateau at low frequencies of the real part of the complex dielectric conductivity [<a href="#B46-nanomaterials-07-00023" class="html-bibr">46</a>], <math display="inline"> <semantics> <msup> <mi mathvariant="sans-serif">σ</mi> <mo>′</mo> </msup> </semantics> </math>, for the samples under investigation: (<b>a</b>) examples of the transient dependence and (<b>b</b>) conductivity at the onset of <math display="inline"> <semantics> <msub> <mi>I</mi> <mrow> <mn>3</mn> <mo>/</mo> <mn>1</mn> </mrow> </msub> </semantics> </math> steady variation as a function of the processing (die) Weissenberg number, <math display="inline"> <semantics> <mrow> <mi>W</mi> <mi>i</mi> </mrow> </semantics> </math>.</p> Full article ">Figure 13
<p>Conductivity in the circuit as a function of the Weissenberg number inside the extrusion die, <math display="inline"> <semantics> <mrow> <mi>W</mi> <mi>i</mi> <mo>=</mo> <mi>λ</mi> <msub> <mover accent="true"> <mi>γ</mi> <mo>˙</mo> </mover> <mi>a</mi> </msub> </mrow> </semantics> </math>, of extruded strands before pelletizing and rheological characterization. Data processed from Arino et al. [<a href="#B3-nanomaterials-07-00023" class="html-bibr">3</a>].</p> Full article ">
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