[go: up one dir, main page]
Next Issue
Volume 7, January
Previous Issue
Volume 6, November
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
8.5
4.4
Journals
Nanomaterials
Volume 6
Issue 12
share announcement

Nanomaterials, Volume 6, Issue 12 (December 2016) – 23 articles

  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Reader to open them.
Order results
Result details
Section
Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:
1888 KiB  
Article
Graphene Oxide Bionanocomposite Coatings with High Oxygen Barrier Properties
by Ilke Uysal Unalan, Derya Boyacı, Masoud Ghaani, Silvia Trabattoni and Stefano Farris
Nanomaterials 2016, 6(12), 244; https://doi.org/10.3390/nano6120244 - 21 Dec 2016
Cited by 18 | Viewed by 5517
Abstract
In this work, we present the development of bionanocomposite coatings on poly(ethylene terephthalate) (PET) with outstanding oxygen barrier properties. Pullulan and graphene oxide (GO) were used as main polymer phase and nanobuilding block (NBB), respectively. The oxygen barrier performance was investigated at different [...] Read more.
In this work, we present the development of bionanocomposite coatings on poly(ethylene terephthalate) (PET) with outstanding oxygen barrier properties. Pullulan and graphene oxide (GO) were used as main polymer phase and nanobuilding block (NBB), respectively. The oxygen barrier performance was investigated at different filler volume fractions (ϕ) and as a function of different relative humidity (RH) values. Noticeably, the impermeable nature of GO was reflected under dry conditions, in which an oxygen transmission rate (OTR, mL·m−2·24 h−1) value below the detection limit of the instrument (0.01 mL·m−2·24 h−1) was recorded, even for ϕ as low as 0.0004. A dramatic increase of the OTR values occurred in humid conditions, such that the barrier performance was totally lost at 90% RH (the OTR of coated PET films was equal to the OTR of bare PET films). Modelling of the experimental OTR data by Cussler’s model suggested that the spatial ordering of GO sheets within the main pullulan phase was perturbed because of RH fluctuations. In spite of the presence of the filler, all the formulations allowed the obtainment of final materials with haze values below 3%, the only exception being the formulation with the highest loading of GO (ϕ ≈ 0.03). The mechanisms underlying the experimental observations are discussed. Full article
(This article belongs to the Special Issue Multifunctional Polymer-Based Nanocomposites)
►▼ Show Figures

Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Transmission electron microscopy (TEM) images of graphene oxide (GO) at (<b>a</b>) 0.2 wt % and (<b>b</b>) 0.02 wt %. Atomic force microscopy (AFM) height images of GO: (<b>c</b>) at 0.2 wt % and 15 × 15 µm<sup>2</sup>; (<b>d</b>) at 0.02 wt % and 40 × 40 µm<sup>2</sup>. A highly wizened morphology is observed in panels (a) and (c), whereas both individual and overlapping sheets of GO are clearly visible in panels (b) and (d).</p> Full article ">Figure 2
<p>Experimental (□) and predicted (—) oxygen transmission rate (OTR) values of bionanocomposite coatings as a function of filler volume fraction (ϕ) for different aspect ratios (α) of GO platelets at (<b>a</b>) 30% RH and (<b>b</b>) 60% RH, according to Cussler’s model (Equation (1) in the text).</p> Full article ">Figure 3
<p>Schematic representation of the pullulan/GO nanocomposite system (<b>a</b>) in dry conditions and upon effect of relative humidity set at (<b>b</b>) 30%; (<b>c</b>) 60%; and (<b>d</b>) 90%.</p> Full article ">Figure 4
<p>Large-scale effect of moisture uptake on the pullulan/GO nanocomposite coating: (<b>a</b>) ordered organization in dry conditions and at low RH values; (<b>b</b>) disordered organization and increased mobility due to the “dilution” effect; (<b>c</b>) discretization of the GO sheets into graphitic domains.</p> Full article ">
4090 KiB  
Article
Synthesis of Antifungal Agents from Xanthene and Thiazine Dyes and Analysis of Their Effects
by Joo Ran Kim and Stephen Michielsen
Nanomaterials 2016, 6(12), 243; https://doi.org/10.3390/nano6120243 - 20 Dec 2016
Cited by 8 | Viewed by 5234
Abstract
Indoor fungi growth is an increasing home health problem as our homes are more tightly sealed. One thing that limits durability of the antifungal agents is the scarcity of reactive sites on many surfaces to attach these agents. In order to increase graft [...] Read more.
Indoor fungi growth is an increasing home health problem as our homes are more tightly sealed. One thing that limits durability of the antifungal agents is the scarcity of reactive sites on many surfaces to attach these agents. In order to increase graft yield of photosensitizers to the fabrics, poly(acrylic acid-co-styrene sulfonic acid-co-vinyl benzyl rose bengal or phloxine B) were polymerized and then grafted to electrospun fabrics. In an alternative process, azure A or toluidine blue O were grafted to poly(acrylic acid), which was subsequently grafted to nanofiber-based and microfiber-based fabrics. The fabrics grafted with photosensitizers induced antifungal effects on all seven types of fungi in the order of rose bengal > phloxine B > toluidine blue O > azure A, which follows the quantum yield production of singlet oxygen for these photoactive dyes. Their inhibition rates for inactivating fungal spores decreased in the order of P. cinnamomi, T. viride, A. niger, A. fumigatus, C. globosum, P. funiculosum, and M. grisea, which is associated with lipid composition in membrane and the morphology of fungal spores. The antifungal activity was also correlated with the surface area of fabric types which grafted the photosensitizer covalently on the surface as determined by the bound color strength. Full article
►▼ Show Figures

Figure 1

Figure 1
<p>Nanofibers using electrospinning using roller collector, (<b>a</b>) nylon 6,6 fabric consisting of nanofibers with average diameter 505 nm (σ = 152.5 nm); and (<b>b</b>) melt spun microfibers (Cerex Spectramax<sup>®</sup> nylon 6,6) with diameter 17.3 µm (σ = 0.86 µm).</p> Full article ">Figure 2
<p>The grafting scheme of poly(acrylic acid-co-styrene sulfonic acid-co-vinyl benzyl rose bengal or phloxine B) or thiazine dyes grafted with poly(acrylic acid) (PAA) to the nylon fiber forming random coil shape. D is polymerized dye molecule such as polymerized xanthene dyes or thiazine dyes grafted with PAA. For RB, R<sub>1</sub> and R<sub>2</sub> are I and Cl. For PB, R<sub>1</sub> and R<sub>2</sub> are Br and Cl and TBO has methyl group at R<sub>8</sub>. Rose Bengal = RB; phloxine B = PB; toluidine blue O = TBO.</p> Full article ">Figure 3
<p>The inhibition zone test of nano and micro fabric grafted with RB, PB, AA and TBO on (<b>a</b>) <span class="html-italic">P. cinnamomi</span>; (<b>b</b>) <span class="html-italic">T. viride</span>; and (<b>c</b>) <span class="html-italic">M. grisea</span>, The 1st column is the control, the 2nd is the nano fabric grafted with RB, the 3rd is the nano fabric grafted with PB, the 4th is the micro fabric grafted with RB, the 5th is the micro fabric grafted PB, the 6th is the nano fabric grafted with TBO, the 7th is the nano fabric grafted with azure A (AA).</p> Full article ">Figure 4
<p>The optical density (OD) reduction by nano and micro fabrics grafted with RB, PB, TBO, and AA graphed as a function of time under illumination on (<b>a</b>) <span class="html-italic">A. niger</span>; (<b>b</b>) <span class="html-italic">A. fumigatus</span>; (<b>c</b>) <span class="html-italic">T. viride</span>; (<b>d</b>) <span class="html-italic">C. globosum</span>; (<b>e</b>) <span class="html-italic">P. funiculosum</span>; (<b>f</b>) <span class="html-italic">M. grisea</span>; and (<b>g</b>) <span class="html-italic">P. cinnamomi</span>. Note: all axes are to the same scale to aid comparisons between materials.</p> Full article ">Figure 5
<p>Inhibition percentages of the nano and micro fabrics with immobilized RB, PB, AA, and TBO photosensitizers on (<b>a</b>) <span class="html-italic">A. fumigatus</span>; (<b>b</b>) <span class="html-italic">A. niger</span>; (<b>c</b>) <span class="html-italic">T. viride</span>; (<b>d</b>) <span class="html-italic">C. globosum</span>; (<b>e</b>) <span class="html-italic">P. funiculosum</span>; (<b>f</b>) <span class="html-italic">P. cinnamomi</span>; and (<b>g</b>) <span class="html-italic">M. grisea</span>.</p> Full article ">Figure 6
<p>The relationship between antimicrobial activity and properties of microorganism: (<b>a</b>) the graph of the inhibition percent and surface area of spores; (<b>b</b>) photooxidation of ergosterol to ergoperoxide in ascomycota fungal membrane [<a href="#B34-nanomaterials-06-00243" class="html-bibr">34</a>]; (<b>c</b>) eicosapentaenoic acid (EPA); (<b>d</b>) arachidonic acid (AR); (<b>e</b>) reactions on double bonds by singlet oxygen in unsaturated fatty acid chains.</p> Full article ">Figure 6 Cont.
<p>The relationship between antimicrobial activity and properties of microorganism: (<b>a</b>) the graph of the inhibition percent and surface area of spores; (<b>b</b>) photooxidation of ergosterol to ergoperoxide in ascomycota fungal membrane [<a href="#B34-nanomaterials-06-00243" class="html-bibr">34</a>]; (<b>c</b>) eicosapentaenoic acid (EPA); (<b>d</b>) arachidonic acid (AR); (<b>e</b>) reactions on double bonds by singlet oxygen in unsaturated fatty acid chains.</p> Full article ">
1730 KiB  
Article
Vibration of Piezoelectric ZnO-SWCNT Nanowires
by Yao Xiao, Chengyuan Wang and Yuantian Feng
Nanomaterials 2016, 6(12), 242; https://doi.org/10.3390/nano6120242 - 15 Dec 2016
Cited by 3 | Viewed by 4546
Abstract
A hybrid nanowire (HNW) was constructed by coating a single-wall carbon nanotube (SWCNT) with piezoelectric zinc oxide (ZnO). The two components of the HNW interact with each other via the van der Waals (vdW) force. This paper aims to study the effect of [...] Read more.
A hybrid nanowire (HNW) was constructed by coating a single-wall carbon nanotube (SWCNT) with piezoelectric zinc oxide (ZnO). The two components of the HNW interact with each other via the van der Waals (vdW) force. This paper aims to study the effect of the piezoelectricity in the ZnO layer and the inter-phase vdW interaction on the fundamental vibration of the HNWs. In doing this, a new model was developed where the two components of the HNWs were modeled as Euler beams coupled via the interphase vdW interaction. Based on the model, the dependence of the frequency on an applied electrical voltage was calculated for HNWs of different geometric sizes to reveal the voltage effect. The results were then compared with those calculated without considering the inter-phase vdW interaction. It was found that the interphase vdW interaction can substantially decrease the structural stiffness, leading to a greatly enhanced piezoelectric effect but a lower frequency for the vibration of the HNWs. Full article
(This article belongs to the Special Issue Piezoelectric Nanomaterials)
►▼ Show Figures

Figure 1

Figure 1
<p>Schematic illustration of the hybrid nanowire (HNW) structure where a single-wall carbon nanotube (SWCNT) of radius <span class="html-italic">R</span> is coated by a cylindrical layer of ZnO of thickness <span class="html-italic">t</span>. The SWCNT and ZnO layer are bonded via the van der Waals (vdW) interaction with equilibrium interspacing <span class="html-italic">s</span>.</p> Full article ">Figure 2
<p>Frequencies of piezoelectric HNWs with interphase vdW interaction where the voltage applied is in the range of (−0.2 V, 0.003 V), and the inner SWCNT has a radius (<b>a</b>) <span class="html-italic">R</span> = 0.68 nm and (<b>b</b>) <span class="html-italic">R</span> = 2.51 nm. The insets show the results for <span class="html-italic">U</span> = 0.001, 0.002 and 0.003 V.</p> Full article ">Figure 3
<p>Frequency ratio <math display="inline"> <semantics> <mrow> <mi>f</mi> <mo>/</mo> <msub> <mi>f</mi> <mn>0</mn> </msub> </mrow> </semantics> </math> calculated at <span class="html-italic">U</span> = −0.2, −0.1, 0 V. The inset shows the corresponding results associated with <span class="html-italic">U</span> = 0.001, 0.002, 0.003 V.</p> Full article ">Figure 4
<p>Frequencies calculated without considering the interphase vdW interaction for the HNWs where the SWCNT radius <span class="html-italic">R</span> is (<b>a</b>) 0.68 nm and (<b>b</b>) 2.51 nm, respectively.</p> Full article ">Figure 5
<p>Frequency ratio <math display="inline"> <semantics> <mrow> <msub> <mi>f</mi> <mrow> <mi>v</mi> <mi>d</mi> <mi>w</mi> </mrow> </msub> <mo>/</mo> <msub> <mi>f</mi> <mrow> <mi>n</mi> <mo>−</mo> <mi>v</mi> <mi>d</mi> <mi>w</mi> </mrow> </msub> </mrow> </semantics> </math> calculated for the HWNs with the SWCNT radius <span class="html-italic">R</span> equal to (<b>a</b>) 0.68 nm and (<b>b</b>) 2.51 nm.</p> Full article ">
6432 KiB  
Article
Effect of Nano-SiO2 on the Hydration and Microstructure of Portland Cement
by Liguo Wang, Dapeng Zheng, Shupeng Zhang, Hongzhi Cui and Dongxu Li
Nanomaterials 2016, 6(12), 241; https://doi.org/10.3390/nano6120241 - 15 Dec 2016
Cited by 136 | Viewed by 6769
Abstract
This paper systematically studied the modification of cement-based materials by nano-SiO2 particles with an average diameter of about 20 nm. In order to obtain the effect of nano-SiO2 particles on the mechanical properties, hydration, and pore structure of cement-based materials, adding [...] Read more.
This paper systematically studied the modification of cement-based materials by nano-SiO2 particles with an average diameter of about 20 nm. In order to obtain the effect of nano-SiO2 particles on the mechanical properties, hydration, and pore structure of cement-based materials, adding 1%, 3%, and 5% content of nano-SiO2 in cement paste, respectively. The results showed that the reaction of nano-SiO2 particles with Ca(OH)2 (crystal powder) started within 1 h, and formed C–S–H gel. The reaction speed was faster after aging for three days. The mechanical properties of cement-based materials were improved with the addition of 3% nano-SiO2, and the early strength enhancement of test pieces was obvious. Three-day compressive strength increased 33.2%, and 28-day compressive strength increased 18.5%. The exothermic peak of hydration heat of cement increased significantly after the addition of nano-SiO2. Appearance time of the exothermic peak was advanced and the total heat release increased. Thermogravimetric-differential scanning calorimetry (TG-DSC) analysis showed that nano-SiO2 promoted the formation of C–S–H gel. The results of mercury intrusion porosimetry (MIP) showed that the total porosity of cement paste with 3% nano-SiO2 was reduced by 5.51% and 5.4% at three days and 28 days, respectively, compared with the pure cement paste. At the same time, the pore structure of cement paste was optimized, and much-detrimental pores and detrimental pores decreased, while less harmful pores and innocuous pores increased. Full article
►▼ Show Figures

Figure 1

Figure 1
<p>(<b>a</b>) Scanning electron microscopic (SEM) patterns of nano-silica; (<b>b</b>) X-ray diffraction (XRD) patterns of nano-silica.</p> Full article ">Figure 2
<p>SEM images of microstructure of the products at different ages: (<b>a</b>) 1day; (<b>b</b>) 3 days; (<b>c</b>) 7 days; (<b>d</b>) 28 days. 1, 2, 3, 4 are the position numbers in <a href="#nanomaterials-06-00241-t007" class="html-table">Table 7</a>.</p> Full article ">Figure 3
<p>XRD patterns of the reaction of nano-SiO<sub>2</sub> with Ca(OH)<sub>2</sub>.</p> Full article ">Figure 4
<p>Thermogravimetric-differential scanning calorimetry (TG-DSC) curves of the products of the reaction of nano-SiO<sub>2</sub> with Ca(OH)<sub>2</sub>.</p> Full article ">Figure 5
<p>The mass loss of Ca(OH)<sub>2</sub> at different ages.</p> Full article ">Figure 6
<p>Flexural and compressive strength of cement contained Nano-SiO<sub>2</sub>. (<b>a</b>) Flexural strength; and (<b>b</b>) compressive strength.</p> Full article ">Figure 7
<p>Effect of nano-SiO<sub>2</sub> on cement hydration exothermic rate and hydration heat.</p> Full article ">Figure 8
<p>XRD patterns of cement pastes with 3% or without of nano-SiO<sub>2</sub> at different ages: (<b>a</b>) one day; (<b>b</b>) three days; (<b>c</b>) seven days; and (<b>d</b>) 28 days.</p> Full article ">Figure 9
<p>TG-DSC curves of cement pastes with 3% or without of nano-SiO<sub>2</sub> at different ages: (<b>a</b>) 1 day; (<b>b</b>) 3 days; (<b>c</b>) 7 days; and (<b>d</b>) 28 days.</p> Full article ">Figure 10
<p>The mass loss of Ca(OH)<sub>2</sub> at difference ages.</p> Full article ">Figure 11
<p>SEM images: (<b>a</b>) control cement at three days (<b>b</b>) cement with nano-SiO<sub>2</sub> 3% at three days (<b>c</b>) control cement at 28 days; and (<b>d</b>) cement with nano-SiO<sub>2</sub> 3% at 28 days.</p> Full article ">Figure 11 Cont.
<p>SEM images: (<b>a</b>) control cement at three days (<b>b</b>) cement with nano-SiO<sub>2</sub> 3% at three days (<b>c</b>) control cement at 28 days; and (<b>d</b>) cement with nano-SiO<sub>2</sub> 3% at 28 days.</p> Full article ">Figure 12
<p>Pore size distribution of cement pastes with 3% or without nano-SiO<sub>2</sub> at different ages: (<b>a</b>) 1 day; (<b>b</b>) 3 days; (<b>c</b>) 7 days; and (<b>d</b>) 28 days.</p> Full article ">Figure 13
<p>The pore size distribution and porosity of set cement paste with different days.</p> Full article ">
4910 KiB  
Article
Shape Evolution of Hierarchical W18O49 Nanostructures: A Systematic Investigation of the Growth Mechanism, Properties and Morphology-Dependent Photocatalytic Activities
by Guojuan Hai, Jianfeng Huang, Liyun Cao, Yanni Jie, Jiayin Li and Xing Wang
Nanomaterials 2016, 6(12), 240; https://doi.org/10.3390/nano6120240 - 14 Dec 2016
Cited by 16 | Viewed by 5793
Abstract
Hierarchical tungsten oxide assemblies such as spindle-like structures, flowers with sharp petals, nanowires and regular hexagonal structures are successfully synthesized via a solvothermal reduction method by simply adjusting the reaction conditions. On the basis of the experimental results, it is determined that the [...] Read more.
Hierarchical tungsten oxide assemblies such as spindle-like structures, flowers with sharp petals, nanowires and regular hexagonal structures are successfully synthesized via a solvothermal reduction method by simply adjusting the reaction conditions. On the basis of the experimental results, it is determined that the reaction time significantly influences the phase transition, microstructure and photocatalytic activity of the prepared samples. The possible mechanisms for the morphology evolution process have been systematically proposed. Moreover, the as-prepared products exhibit significant morphology-dependent photocatalytic activity. The flower-like W18O49 prepared at 6 h possesses a large specific surface area (150.1 m2∙g−1), improved separation efficiency of electron-hole pairs and decreased electron-transfer resistance according to the photoelectrochemical measurements. As a result, the flower-like W18O49 prepared at 6 h exhibits the highest photocatalytic activity for the degradation of Methyl orange aqueous solution. The radical trap experiments showed that the degradation of MO was driven mainly by the participation of h+ and •O2− radicals. Full article
►▼ Show Figures

Figure 1

Figure 1
<p>X-ray powder diffractometer (XRD) patterns of the products prepared under different solvothermal reaction times.</p> Full article ">Figure 2
<p>Scanning electron microscopy (SEM) images of the products prepared under different solvothermal reaction times: (<b>a</b>,<b>b</b>) 1 h; (<b>c</b>,<b>d</b>) 3 h; (<b>e</b>,<b>f</b>) 6 h; (<b>g</b>,<b>h</b>) 12 h.</p> Full article ">Figure 3
<p>Transmission electron microscope (TEM) images of the products prepared with different reaction times: (<b>a</b>) 3 h; (<b>c</b>) 6 h. Corresponding selected area electron diffraction (SAED) patterns were obtained at the center of the red rectangles in the TEM images: (<b>b</b>) 3 h; (<b>d</b>) 6 h.</p> Full article ">Figure 4
<p>X-ray photoelectron spectroscopy (XPS) spectra of the products prepared at 12 h.</p> Full article ">Figure 5
<p>Schematic illustrations: (<b>a</b>) the possible formation mechanism of the products obtained at different reaction time; (<b>b</b>) the crystal structure of W<sub>18</sub>O<sub>49</sub>; (<b>c</b>) the crystal structure of WO<sub>3</sub>·0.33H<sub>2</sub>O.</p> Full article ">Figure 6
<p>UV-Vis diffuses reflectance spectra of the products prepared under different solvothermal reaction times.</p> Full article ">Figure 7
<p>Photocatalytic properties of the products prepared under different solvothermal reaction times: (<b>a</b>) UV-light irradiation; (<b>b</b>) visible-light irradiation.</p> Full article ">Figure 8
<p>Trapping experiment of active species during the photocatalytic degradation of MO over W<sub>18</sub>O<sub>49</sub> (6 h) sample under visible light irradiation.</p> Full article ">Figure 9
<p>N<sub>2</sub> absorption-desorption isotherms of the products prepared under different solvothermal reaction times: (<b>a</b>) 1 h; (<b>b</b>) 3 h; (<b>c</b>) 6 h; (<b>d</b>) 12 h.</p> Full article ">Figure 10
<p>Photocurrent response of the products prepared under different solvothermal reaction times.</p> Full article ">Figure 11
<p>Electrochemical impedance spectra (EIS) Nyquist plots of the products prepared under different solvothermal reaction times: (<b>a</b>) 1 h; (<b>b</b>) 3 h; (<b>c</b>) 6 h; (<b>d</b>) 12 h.</p> Full article ">
3682 KiB  
Review
Investigating Polymer–Metal Interfaces by Grazing Incidence Small-Angle X-Ray Scattering from Gradients to Real-Time Studies
by Matthias Schwartzkopf and Stephan V. Roth
Nanomaterials 2016, 6(12), 239; https://doi.org/10.3390/nano6120239 - 10 Dec 2016
Cited by 33 | Viewed by 9172
Abstract
Tailoring the polymer–metal interface is crucial for advanced material design. Vacuum deposition methods for metal layer coating are widely used in industry and research. They allow for installing a variety of nanostructures, often making use of the selective interaction of the metal atoms [...] Read more.
Tailoring the polymer–metal interface is crucial for advanced material design. Vacuum deposition methods for metal layer coating are widely used in industry and research. They allow for installing a variety of nanostructures, often making use of the selective interaction of the metal atoms with the underlying polymer thin film. The polymer thin film may eventually be nanostructured, too, in order to create a hierarchy in length scales. Grazing incidence X-ray scattering is an advanced method to characterize and investigate polymer–metal interfaces. Being non-destructive and yielding statistically relevant results, it allows for deducing the detailed polymer–metal interaction. We review the use of grazing incidence X-ray scattering to elucidate the polymer–metal interface, making use of the modern synchrotron radiation facilities, allowing for very local studies via in situ (so-called “stop-sputter”) experiments as well as studies observing the nanostructured metal nanoparticle layer growth in real time. Full article
(This article belongs to the Special Issue Multifunctional Polymer-Based Nanocomposites)
►▼ Show Figures

Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Scheme of an in situ sputter deposition experiment combined with grazing incidence small-angle X-ray scattering (GISAXS). The angle between the incident monochromatic X-ray beam and the sample surface is denoted by α<span class="html-italic"><sub>i</sub></span>, the corresponding exit angle by α<span class="html-italic"><sub>f</sub></span>, and the out-of-plane angle by 2θ<span class="html-italic"><sub>f</sub></span>. A reciprocal space <span class="html-italic">(q<sub>y</sub></span>, <span class="html-italic">q<sub>z</sub>)</span> coordinate systems is indicated. The origin of coordinates of <span class="html-italic">q<sub>y</sub></span> and <span class="html-italic">q<sub>z</sub></span> is indicated by the direct beam positions. The red and green rectangles in the 2D GISAXS pattern mark the region of the detector cut and out-of-plane cut, respectively. Adapted from reference [<a href="#B133-nanomaterials-06-00239" class="html-bibr">133</a>] with permission from the Royal Society of Chemistry, 2013.</p> Full article ">Figure 2
<p>(<b>a</b>) Sketch of the nanostructure of the gradient sputter deposited Au clusters/polystyrene (PS) system. The sputter deposited Au clusters are depictured as mixture of spheroidal and cylindrical nano-objects. The gradient is in <span class="html-italic">y</span> direction. The clusters are on top of the PS film with height <span class="html-italic">H</span>, particle diameter 2<span class="html-italic">R</span> and center-to-center distance ξ. (<b>b</b>) Radius <span class="html-italic">R</span> and distance ξ as a function of position <span class="html-italic">y</span> in the gradient. Clearly, three regimes are visible: I–coalesced Au layer, II–isolated nanoparticle layer, III–complete suppression of coalescence, only small particles prevail. Reproduced with the permission from [<a href="#B150-nanomaterials-06-00239" class="html-bibr">150</a>]. Copyright AIP Publishing, 2006.</p> Full article ">Figure 3
<p>(<b>a</b>) Schematic representation of the Au cluster growth during sputter deposition on poly(<span class="html-italic">N</span>-vinylcarbazole) (PVK). Four growth regimes are visible with increasing surface coverage: nucleation (1), lateral cluster growth (2), coarsening (3), vertical cluster growth (4). (<b>b</b>) GISAXS pattern (top) and corresponding model-based simulations (bottom) obtained during stop-sputter deposition Au on a conducting polymer. The deposited layer thickness is indicated. Reproduced with permission from [<a href="#B198-nanomaterials-06-00239" class="html-bibr">198</a>]. Copyright American Chemical Society, 2009.</p> Full article ">Figure 4
<p>Au sputter deposition on amorphous silicon oxide: (<b>a</b>) Evolution of aspect ratio 2<span class="html-italic">R/D</span> (blue symbols, <span class="html-italic">R</span> = radius, <span class="html-italic">D</span> = center-to-center distance of the Au clusters), coverage θ (red symbols) and porosity Φ (green symbols) as a function of effective thickness δ ≈ 0.0032 nm/frame of Au on SiO<span class="html-italic"><sub>x</sub></span>. (<b>b</b>) Schematic side view of the four gold cluster growth regimes with the predominant processes: Nucleation (I), diffusion-mediated coalescence (II) (<span class="html-italic">D &gt; 2R</span>), and adsorption-mediated cluster growth (III) until the percolation threshold (<span class="html-italic">D = 2R</span>). Afterwards, movement of grain boundaries leads to a permanent growth of a dominant cluster at the expense of the adjacent clusters (IV). Adapted from reference [<a href="#B133-nanomaterials-06-00239" class="html-bibr">133</a>] with permission from the Royal Society of Chemistry, 2013.</p> Full article ">Figure 5
<p>Sputter deposition of Au on amorphous silicon oxide. The upper rows shows the grazing incidence small-angle X-ray scattering (GISAXS) data at δ<sub>Au</sub> = 6.3 nm (upper left pattern), compared with model-based simulations of expected GISAXS pattern for different cluster geometries (upper row). The geometry of the cluster is depicted in the upper right corner of each pattern. The form factor of the clusters leads to characteristic shapes of the out-of-plane peaks (in horizontal direction) and leads to changes in the intensity and sharpness of height modulations (vertical direction). The curvature of the 2D intensity distribution in the region of the white triangle is indicative of the spheroidal geometry. The lower row depicts the expected GISAXS pattern, obtained by simulations, of spherical clusters with different cluster-to-substrate angle (<span class="html-italic">CA</span>), i.e. truncated spheres (lower row). A hemisphere corresponds to <span class="html-italic">CA</span> = 90°, which perfectly matches the data. The white number denotes angle between scattering plane and second order height maxima (dashed white lines). Adapted from reference [<a href="#B133-nanomaterials-06-00239" class="html-bibr">133</a>] with permission from the Royal Society of Chemistry, 2013.</p> Full article ">Figure 6
<p>Sputter deposition of Ag on amorphous silicon oxide. (<b>a</b>) Surface enhanced Raman scattering (SERS) signals from 10<sup>−7</sup> mM thiophenol at different deposited silver thicknesses, having different sputter deposited Ag nanostructures on amorphous silicon oxide. The inset shows SERS signal as a function of wavelength for different Ag layer thicknesses. (<b>b</b>) Upper row: GISAXS data (upper row) at the different Ag thicknesses indicated above each pattern. Middle row: Model-based simulations (middle row) of the expected GISAXS pattern of the corresponding real-space model (bottom row). The maximum SERS signal corresponds to an effective Ag thickness of δ<sub>Ag</sub> = 5.6 nm. <span class="html-italic">D</span> denotes the center-to-center distance, <span class="html-italic">R</span> the cluster radius and Δ the void size. Reproduced with permission from [<a href="#B169-nanomaterials-06-00239" class="html-bibr">169</a>]. Copyright AIP Publishing, 2014.</p> Full article ">Figure 7
<p>Sputter deposition of Al on Alq3. Three-step growth mechanism similar to Stranski-Krastanov growth for Al, sputter deposited on Alq3. The three stages correspond to the establishment of an enrichment layer with no cluster structures (Stage I), cluster growth on top of the enrichment layer (Stage II), and subsequent columnar growth (Stage III) with increasing Al layer thickness. Reproduced with permission from [<a href="#B168-nanomaterials-06-00239" class="html-bibr">168</a>]. Copyright American Chemical Society, 2013.</p> Full article ">Figure 8
<p>Sputter deposition of Au on PS. (<b>a</b>) Upper row: Selected 2D GISAXS patterns illustrate the changes in the GISAXS pattern with increasing effective Au film thicknesses δ<sub>Au</sub>. The critical angles of PS and Au are indicated by the blue and orange arrows, respectively. The beam stop to shadow the specular reflected beam is seen as the black circle, while the intermodule gap is visible as a horizontal black stripe. (<span class="html-italic">q<sub>y</sub>, q<sub>z</sub></span>) denote the reciprocal space coordinate systems. Middle row: model-based simulation of the GISAXS pattern, based on the object shape sketched in the upper right corners. Lower row: Sketch of the cluster growth morphology with ongoing sputter deposition in the four regimes (I–nucleation &amp; islands growth; II–partial coalescence; III–domain coarsening; IV–percolation &amp; layer growth) is indicated (<b>b</b>) Change in optical reflectivity <span class="html-italic">r%</span> during the deposition process as a function of wavelength <math display="inline"> <semantics> <mrow> <msub> <mi mathvariant="sans-serif">λ</mi> <mrow> <mi>opt</mi> </mrow> </msub> </mrow> </semantics> </math> and effective thickness δ<sub>Au</sub> and optical micro-graph of a corresponding Au gradient, illustrating the change in optical reflectivity of the pristine grey-blue PS film from dark blue color due to the presence of isolated nanoclusters at the interface to bright red color stemming from larger Au aggregates. Reproduced with permission from [<a href="#B144-nanomaterials-06-00239" class="html-bibr">144</a>]. Copyright American Chemical Society, 2015.</p> Full article ">
2747 KiB  
Article
Nano Copper Oxide-Modified Carbon Cloth as Cathode for a Two-Chamber Microbial Fuel Cell
by Feng Dong, Peng Zhang, Kexun Li, Xianhua Liu and Pingping Zhang
Nanomaterials 2016, 6(12), 238; https://doi.org/10.3390/nano6120238 - 9 Dec 2016
Cited by 9 | Viewed by 6708
Abstract
In this work, Cu2O nanoparticles were deposited on a carbon cloth cathode using a facile electrochemical method. The morphology of the modified cathode, which was characterized by scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) tests, showed that the porosity and specific [...] Read more.
In this work, Cu2O nanoparticles were deposited on a carbon cloth cathode using a facile electrochemical method. The morphology of the modified cathode, which was characterized by scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) tests, showed that the porosity and specific surface area of the cathode improved with longer deposition times. X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV) results showed that cupric oxide and cuprous oxide coexisted on the carbon cloth, which improved the electrochemical activity of cathode. The cathode with a deposition time of 100 s showed the best performance, with a power density twice that of bare carbon cloth. Linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) results revealed that moderate deposition of nano copper oxide on carbon cloth could dramatically reduce the charge transfer resistance, which contributed to the enhanced electrochemical performance. The mediation mechanism of copper oxide nanocatalyst was illustrated by the fact that the recycled conversion between cupric oxide and cuprous oxide accelerated the electron transfer efficiency on the cathode. Full article
►▼ Show Figures

Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Scanning electron microscopy (SEM) images of the surface of copper oxide-coated carbon cloth. These carbon cloths were modified with deposition times of 0 (<b>a</b>), 50 (<b>b</b>), 100 (<b>c</b>), and 150 s (<b>d</b>), respectively.</p> Full article ">Figure 2
<p>X-ray photoelectron spectroscopy (XPS) spectra of the cathode materials. (<b>a</b>) Wide-scan XPS survey spectra of the modified carbon cloth after being applied as cathode in the microbial fuel cell (MFC) for a period of time. Inset: bare carbon cloth. (<b>b</b>) Cu 2p core-level. (<b>c</b>) The XPS spectrum of the unused copper-coated carbon cloth; the upper and lower part were the spectra of Cu 2p and Cu LMM (L-inner level-M-inner level-M-inner level electron transition), respectively. This material had been dried at room temperature for 24 h.</p> Full article ">Figure 3
<p>Power densities of four microbial fuel cells (MFCs) with different deposition times.</p> Full article ">Figure 4
<p>Cyclic voltammetry (CV) of copper-coated carbon cloths. These carbon cloths had deposition times of 0, 50, 100 and 150 s, respectively.</p> Full article ">Figure 5
<p>Linear sweep voltammetry (LSV) curves of the bare carbon cloth and the Cu oxide-coated carbon cloths with different deposition times in a 50 mM potassium ferricyanide solution.</p> Full article ">Figure 6
<p>Nyquist plots of electrochemical impedance spectroscopy (EIS) by the Cu oxide-coated carbon cloths with different deposition times.</p> Full article ">Figure 7
<p>The mechanism of Cu oxide’s intermediation functions on the cathode in ferricyanide solution. The CuO on the cathode surface is first reduced to Cu<sub>2</sub>O by the electrons from the anode, and then Cu<sub>2</sub>O is oxidized to CuO by the ferricyanide. This redox cycle can accelerate the charge transfer rate on the cathode surface.</p> Full article ">
1860 KiB  
Article
Antibacterial Properties of Visible-Light-Responsive Carbon-Containing Titanium Dioxide Photocatalytic Nanoparticles against Anthrax
by Der-Shan Sun, Jyh-Hwa Kau, Hsin-Hsien Huang, Yao-Hsuan Tseng, Wen-Shiang Wu and Hsin-Hou Chang
Nanomaterials 2016, 6(12), 237; https://doi.org/10.3390/nano6120237 - 9 Dec 2016
Cited by 23 | Viewed by 5263
Abstract
The bactericidal activity of conventional titanium dioxide (TiO2) photocatalyst is effective only on irradiation by ultraviolet light, which restricts the applications of TiO2 for use in living environments. Recently, carbon-containing TiO2 nanoparticles [TiO2(C) NP] were found to [...] Read more.
The bactericidal activity of conventional titanium dioxide (TiO2) photocatalyst is effective only on irradiation by ultraviolet light, which restricts the applications of TiO2 for use in living environments. Recently, carbon-containing TiO2 nanoparticles [TiO2(C) NP] were found to be a visible-light-responsive photocatalyst (VLRP), which displayed significantly enhanced antibacterial properties under visible light illumination. However, whether TiO2(C) NPs exert antibacterial properties against Bacillus anthracis remains elusive. Here, we evaluated these VLRP NPs in the reduction of anthrax-induced pathogenesis. Bacteria-killing experiments indicated that a significantly higher proportion (40%–60%) of all tested Bacillus species, including B. subtilis, B. cereus, B. thuringiensis, and B. anthracis, were considerably eliminated by TiO2(C) NPs. Toxin inactivation analysis further suggested that the TiO2(C) NPs efficiently detoxify approximately 90% of tested anthrax lethal toxin, a major virulence factor of anthrax. Notably, macrophage clearance experiments further suggested that, even under suboptimal conditions without considerable bacterial killing, the TiO2(C) NP-mediated photocatalysis still exhibited antibacterial properties through the reduction of bacterial resistance against macrophage killing. Our results collectively suggested that TiO2(C) NP is a conceptually feasible anti-anthrax material, and the relevant technologies described herein may be useful in the development of new strategies against anthrax. Full article
(This article belongs to the Special Issue Antimicrobial Nanomaterials and Nanotechnology)
►▼ Show Figures

Figure 1

Figure 1
<p>Scanning electron microscopy and ultraviolet-visible (UV-Vis) absorption spectrum analyses. Scanning electron microscopy (<b>A</b>,<b>B</b>), X-ray photoelectron spectroscopy (XPS) analysis for the 1s atomic orbital of carbon (<b>C</b>) and UV-Vis absorption spectra (<b>D</b>) of UV100 TiO<sub>2</sub> and C200 NPs used in this study. The C200 sample absorbed light extending into the visible (&gt;380 nm) region.</p> Full article ">Figure 2
<p>Dose-dependent and kinetic analyses of bactericidal activity of C200 NPs against <span class="html-italic">B. subtilis</span>. Dose-dependent (<b>A</b>) and kinetic (<b>B</b>) analyses of the bactericidal activity of UV100 TiO<sub>2</sub> and C200 NPs against <span class="html-italic">B. subtilis</span> after visible-light illumination. Illumination was carried out either at different light densities (at distances of 5 cm, 10 cm and 15 cm with respective illumination intensities of 3 × 10<sup>4</sup>, 1.2 × 10<sup>3</sup> and 3 × 10<sup>2</sup> lux) for 30 min (<b>A</b>) or at a light density of 3 × 10<sup>4</sup> lux (90 mW/cm<sup>2</sup>) for different periods (<b>B</b>). Under each illumination condition, the surviving bacteria in the UV100 TiO<sub>2</sub> groups were normalized to 100%. * <span class="html-italic">P</span> &lt; 0.05 and ** <span class="html-italic">P</span> &lt; 0.01 compared with the respective UV100 TiO<sub>2</sub> groups. <span class="html-italic">n</span> = 6, three experiments with two replicates.</p> Full article ">Figure 3
<p>Antibacterial properties of C200 NPs against vegetative bacteria and spores of <span class="html-italic">Bacillus</span> species. Bacteria <span class="html-italic">B. subtilis</span>, <span class="html-italic">B. thuringiensis</span>, <span class="html-italic">B. cereus</span>, and <span class="html-italic">B. anthracis</span> were photocatalyzed using UV100 TiO<sub>2</sub> and C200 NPs, respectively. All vegetative bacteria (<b>A</b>) or spores (<b>B</b>) in the UV100 TiO<sub>2</sub> groups were normalized to 100%. The relative percentages of surviving pathogens in the C200 groups are shown. The illumination intensity was 3 × 10<sup>4</sup> lux (90 mW/cm<sup>2</sup>), and the reaction time was 30 min. * <span class="html-italic">P</span> &lt; 0.05 and ** <span class="html-italic">P</span> &lt; 0.01 compared with respective UV100 TiO<sub>2</sub> groups. <span class="html-italic">n</span> = 6, three experiments with two replicates.</p> Full article ">Figure 4
<p>Visible-light-responsive C200 NP-mediated inactivation of lethal toxin (LT). Macrophage J774A.1 cells were treated with LT with or without UV100 TiO<sub>2</sub> and C200 photocatalysis for 3 h, and surviving cells of untreated groups were adjusted to 100%. Columns designated UV TiO<sub>2</sub> or C200 represent that LT was pretreated with photocatalysis by using UV100 TiO<sub>2</sub> or C200 NPs, respectively, before being treated with J774A.1 cells. ** <span class="html-italic">P</span> &lt; 0.01, compared with all other groups treated with LT (with or without additional treatments). <span class="html-italic">n</span> = 6, three experiments with two replicates.</p> Full article ">Figure 5
<p>Surviving <span class="html-italic">B. subtilis</span> after clearance by macrophages. <span class="html-italic">B. subtilis</span> was treated with J774A.1 macrophage cells (multiplicity of infection (MOI): 0.1 bacteria/cell). Levels of surviving bacteria (colony-forming unit; CFU) harvested from macrophage cell lysate are shown. Columns designated UV TiO<sub>2</sub> and C200 represent that anthrax spores were pretreated with photocatalysis by using UV100 TiO<sub>2</sub> and C200 NPs, respectively. * <span class="html-italic">P</span> &lt; 0.05, compared with all other groups under the 8 h treatment condition. <span class="html-italic">n</span> = 6, three experiments with two replicates.</p> Full article ">
4503 KiB  
Article
Nickel Based Electrospun Materials with Tuned Morphology and Composition
by Giorgio Ercolano, Filippo Farina, Sara Cavaliere, Deborah J. Jones and Jacques Rozière
Nanomaterials 2016, 6(12), 236; https://doi.org/10.3390/nano6120236 - 6 Dec 2016
Cited by 17 | Viewed by 5907
Abstract
Nickel is set to play a crucial role to substitute the less-abundant platinum in clean electrochemical energy conversion and storage devices and catalysis. The controlled design of Ni nanomaterials is essential to fine-tune their properties to match these applications. A systematic study of [...] Read more.
Nickel is set to play a crucial role to substitute the less-abundant platinum in clean electrochemical energy conversion and storage devices and catalysis. The controlled design of Ni nanomaterials is essential to fine-tune their properties to match these applications. A systematic study of electrospinning and thermal post-treatment parameters has been performed to synthesize Ni materials and tune their morphology (fibers, ribbons, and sponge-like structures) and composition (metallic Ni, NiO, Ni/C, Ni3N and their combinations). The obtained Ni-based spun materials have been characterized by scanning and transmission electron microscopy, X-ray diffraction and thermogravimetric analysis. The possibility of upscaling and the versatility of electrospinning open the way to large-scale production of Ni nanostructures, as well as bi- and multi-metal systems for widened applications. Full article
►▼ Show Figures

Figure 1

Figure 1
<p>Schematic representation of the synthesis routes leading to Ni-based one-dimensional (1D) materials by electrospinning and thermal treatments.</p> Full article ">Figure 2
<p>(<b>a</b>) Scanning electron microscopy (SEM) micrograph and (<b>b</b>) corresponding histogram of fiber size distribution of NiO fibers obtained from 12 wt % polyvinylalcohol and 12 wt % nickel acetate in H<sub>2</sub>O.</p> Full article ">Figure 3
<p>SEM micrographs and corresponding histograms of size distribution of NiO electrospun in the same conditions as 9 (<b>a</b>,<b>b</b>), 10 (<b>c</b>,<b>d</b>), 11 wt % (<b>e</b>,<b>f</b>) polyvinylpyrrolidone and nickel acetate in ethanol (<b>a</b>,<b>b</b>) and in ethanol:dimethylformamide (7:3 vol.) (<b>g</b>,<b>h</b>).</p> Full article ">Figure 4
<p>SEM micrographs and corresponding histograms of fiber size distribution of NiO from water/ethanol (<b>a</b>,<b>b</b>) and dimethylformamide/ethanol (<b>c</b>,<b>d</b>).</p> Full article ">Figure 5
<p>X-ray diffraction (XRD) diffractograms of the conversion of NiO to Ni fibers at 250 °C in pure hydrogen (<b>a</b>) vs. H<sub>2</sub>/Ar; and (<b>b</b>) Joint Committee on Powder Diffraction Standards (JCPDS) reference: NiO 96-101-0094, Ni 96-151-2527.</p> Full article ">Figure 6
<p>SEM micrographs of NiO ribbons (obtained from polyvinylpyrrolidone (PVP) and nickel acetate in ethanol) and transmission electron microscope (TEM) micrographs of NiO nanofibers (obtained from PVP and nickel acetate in DMF/ethanol) before (<b>a</b>,<b>c</b>) and after reduction at 250 °C in H<sub>2</sub> (<b>b</b>,<b>d</b>).</p> Full article ">Figure 7
<p>SEM micrographs of electrospun Ni (from polyvinylalcohol and nickel acetate in water) obtained after reduction in H<sub>2</sub> at 250 °C (<b>a</b>) and 400 °C (<b>b</b>).</p> Full article ">Figure 8
<p>TEM micrograph of Ni/C composite fibers (obtained from PVP and nickel acetate in DMF/ethanol at 700 °C under nitrogen (<b>a</b>) and the corresponding XRD diffractogram (<b>b</b>) JCPDS reference: Ni 96-151-2527.</p> Full article ">Figure 9
<p>SEM micrograph of a sponge-like Ni<sub>3</sub>N structure (obtained from NiO nanofibers derived from PVP and nickel acetate in DMF/ethanol) (<b>a</b>) and the corresponding XRD diffractogram (<b>b</b>) before and after the two-step complete conversion in NH<sub>3</sub>. JCPDS reference: Ni<sub>3</sub>N 00-010-280, Ni 96-151-2527.</p> Full article ">Figure 10
<p>SEM of Ni fibers before (<b>a</b>) and after thermal treatment under NH<sub>3</sub> (<b>c</b>) and XRD diffractogram of fibers with different degrees of conversion to the nitride phase (<b>b</b>) JCPDS reference: Ni<sub>3</sub>N 00-010-280, Ni 96-151-2527.</p> Full article ">Figure 11
<p>STEM image of platinum on nickel nanofibres after the galvanic displacement (<b>a</b>), overlay of the EDX maps of Ni (<b>red</b>) and Pt (<b>green</b>) (<b>b</b>) and oxygen reduction reaction (ORR) at 5 mV/s in 0.1 M HClO<sub>4</sub> saturated with O<sub>2</sub> at 400, 900, 1600, 2500 RPM (<b>c</b>).</p> Full article ">
4752 KiB  
Article
Antimicrobial, Antioxidant, and Anticancer Activities of Biosynthesized Silver Nanoparticles Using Marine Algae Ecklonia cava
by Jayachandran Venkatesan, Se-Kwon Kim and Min Suk Shim
Nanomaterials 2016, 6(12), 235; https://doi.org/10.3390/nano6120235 - 6 Dec 2016
Cited by 151 | Viewed by 10857
Abstract
Green synthesis of silver nanoparticles (AgNPs) has gained great interest as a simple and eco-friendly alternative to conventional chemical methods. In this study, AgNPs were synthesized by using extracts of marine algae Ecklonia cava as reducing and capping agents. The formation of AgNPs [...] Read more.
Green synthesis of silver nanoparticles (AgNPs) has gained great interest as a simple and eco-friendly alternative to conventional chemical methods. In this study, AgNPs were synthesized by using extracts of marine algae Ecklonia cava as reducing and capping agents. The formation of AgNPs using aqueous extract of Ecklonia cava was confirmed visually by color change and their surface plasmon resonance peak at 418 nm, measured by UV-visible spectroscopy. The size, shape, and morphology of the biosynthesized AgNPs were observed by transmission electron microscopy and dynamic light scattering analysis. The biosynthesized AgNPs were nearly spherical in shape with an average size around 43 nm. Fourier transform-infrared spectroscopy (FTIR) analysis confirmed the presence of phenolic compounds in the aqueous extract of Ecklonia cava as reducing and capping agents. X-ray diffraction (XRD) analysis was also carried out to demonstrate the crystalline nature of the biosynthesized AgNPs. Antimicrobial results determined by an agar well diffusion assay demonstrated a significant antibacterial activity of the AgNPs against Escherichia coli and Staphylococcus aureus. Antioxidant results determined by 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging assay revealed an efficient antioxidant activity of the biosynthesized AgNPs. The biosynthesized AgNPs also exhibited a strong apoptotic anticancer activity against human cervical cancer cells. Our findings demonstrate that aqueous extract of Ecklonia cava is an effective reducing agent for green synthesis of AgNPs with efficient antimicrobial, antioxidant, and anticancer activities. Full article
(This article belongs to the Special Issue Antimicrobial Nanomaterials and Nanotechnology)
►▼ Show Figures

Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Chemical structures of: (<b>a</b>) phloroglucinol; (<b>b</b>) eckol; (<b>c</b>) fucodiphlorethol G; (<b>d</b>) phlorofucofuroeckol A; (<b>e</b>) 7-phloroeckol; (<b>f</b>) dieckol; (<b>g</b>) 6,6′-bieckol; (<b>h</b>) triphlorethol-A; and (<b>i</b>) 2,7′-phloroglucinol-6,6′-bieckol.</p> Full article ">Figure 2
<p>Schematic representation of green synthesis of AgNPs. <span class="html-italic">Ecklonia cava</span> is collected from the sea and then ground into a fine powder. The aqueous extract of <span class="html-italic">Ecklonia cava</span> is mixed with 1 mM AgNO<sub>3</sub> solution and stirred for 72 h to synthesize AgNPs.</p> Full article ">Figure 3
<p>UV-Vis absorption spectra of biosynthesized AgNPs at different time intervals.</p> Full article ">Figure 4
<p>Thermogravimetric analysis of aqueous extract of <span class="html-italic">Ecklonia cava</span> (black curve) and biosynthesized AgNPs (red curve).</p> Full article ">Figure 5
<p>Fourier transform-infrared spectra of: (<b>A</b>) biosynthesized AgNPs; and (<b>B</b>) aqueous extract of <span class="html-italic">Ecklonia cava</span>.</p> Full article ">Figure 6
<p>X-ray diffraction patterns of biosynthesized AgNPs (dot circle) and AgCl NPs (asterisk).</p> Full article ">Figure 7
<p>(<b>A</b>,<b>B</b>) Transmission electron microscopy images of biosynthesized AgNPs at different magnifications; and (<b>C</b>) particle size distribution of AgNPs determined by DLS.</p> Full article ">Figure 8
<p>Antimicrobial activity of biosynthesized AgNPs, determined by an agar well diffusion assay. Pictures show inhibition zones produced by the biosynthesized AgNPs against <span class="html-italic">E. coli</span> and <span class="html-italic">S. aureus.</span> (<b>A</b>) <span class="html-italic">E. coli</span> colonies treated with: (<b>a</b>) 20 µg of aqueous extract of <span class="html-italic">Ecklonia cava</span>; (<b>b</b>) 40 µg of aqueous extract of <span class="html-italic">Ecklonia cava</span>; (<b>c</b>) 20 µg of AgNPs; and (<b>d</b>) 40 µg of AgNPs. (<b>B</b>) <span class="html-italic">S. aureus</span> colonies treated with: (<b>a</b>) 20 µg of aqueous extract of <span class="html-italic">Ecklonia cava</span>; (<b>b</b>) 40 µg of aqueous extract of <span class="html-italic">Ecklonia cava</span>; (<b>c</b>) 20 µg of AgNPs; and (<b>d</b>) 40 µg of AgNPs.</p> Full article ">Figure 9
<p>1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity of <span class="html-italic">Ecklonia cava</span> extract and biosynthesized AgNPs. (ns: non-significant; * <span class="html-italic">p</span> &lt; 0.05).</p> Full article ">Figure 10
<p>(<b>A</b>) Anticancer activity of biosynthesized AgNPs against HeLa cells (ns: non-significant; *** <span class="html-italic">p</span> &lt; 0.001); and (<b>B</b>) optical microscopy images of HeLa cells after treatment with: (<b>i</b>) 250 µg/mL of <span class="html-italic">Ecklonia cava</span> extracts; and (<b>ii</b>) AgNPs. Scale bars = 100 µm.</p> Full article ">Figure 11
<p>Annexin/PI staining of: (<b>A</b>) untreated HeLa cells; (<b>B</b>) HeLa cells treated with 250 µg/mL of <span class="html-italic">Ecklonia cava</span> extracts; (<b>C</b>) HeLa cells treated with 250 µg/mL of biosynthesized AgNPs; and (<b>D</b>) relative cell population of HeLa cells after treatment with <span class="html-italic">Ecklonia cava</span> extracts and biosynthesized AgNPs.</p> Full article ">
2452 KiB  
Article
The Change of Electronic Transport Behaviors by P and B Doping in Nano-Crystalline Silicon Films with Very High Conductivities
by Dan Shan, Mingqing Qian, Yang Ji, Xiaofan Jiang, Jun Xu and Kunji Chen
Nanomaterials 2016, 6(12), 233; https://doi.org/10.3390/nano6120233 - 3 Dec 2016
Cited by 14 | Viewed by 5013
Abstract
Nano-crystalline Si films with high conductivities are highly desired in order to develop the new generation of nano-devices. Here, we first demonstrate that the grain boundaries played an important role in the carrier transport process in un-doped nano-crystalline Si films as revealed by [...] Read more.
Nano-crystalline Si films with high conductivities are highly desired in order to develop the new generation of nano-devices. Here, we first demonstrate that the grain boundaries played an important role in the carrier transport process in un-doped nano-crystalline Si films as revealed by the temperature-dependent Hall measurements. The potential barrier height can be well estimated from the experimental results, which is in good agreement with the proposed model. Then, by introducing P and B doping, it is found that the scattering of grain boundaries can be significantly suppressed and the Hall mobility is monotonously decreased with the temperature both in P- and B-doped nano-crystalline Si films, which can be attributed to the trapping of P and B dopants in the grain boundary regions to reduce the barriers. Consequently, a room temperature conductivity as high as 1.58 × 103 S/cm and 4 × 102 S/cm is achieved for the P-doped and B-doped samples, respectively. Full article
(This article belongs to the Special Issue Semiconductor Nanoparticles for Electric Device Applications)
►▼ Show Figures

Figure 1

Figure 1
<p>Raman spectra of un-doped nano-crystalline Si (nc-Si) film, P- and B-doped films with <span class="html-italic">F</span><sub>P</sub> = <span class="html-italic">F</span><sub>B</sub> = 5 sccm.</p> Full article ">Figure 2
<p>Transmission electron microscopy (TEM) images of (<b>a</b>) the un-doped nc-Si film; and (<b>b</b>) P-doped nc-Si film; and (<b>c</b>) B-doped nc-Si film.</p> Full article ">Figure 3
<p>X-ray photoelectron spectroscopy (XPS) spectra of doped nc-Si films: (<b>a</b>) P-doped samples with different <span class="html-italic">F</span><sub>P</sub>; and (<b>b</b>) B-doped samples with different <span class="html-italic">F</span><sub>B</sub>.</p> Full article ">Figure 4
<p>Temperature-dependent conductivities of nc-Si films with and without doping.</p> Full article ">Figure 5
<p>The Hall mobility as a function of the reciprocal temperature for the un-doped nc-Si film.</p> Full article ">Figure 6
<p>Schematic energy band diagram of the nc-Si films constituted by nano-crystalline phases and potential barrier caused by grain boundaries.</p> Full article ">Figure 7
<p>The Hall mobility, <math display="inline"> <semantics> <mrow> <msub> <mi mathvariant="sans-serif">μ</mi> <mi mathvariant="normal">H</mi> </msub> </mrow> </semantics> </math>, as a function of temperature for the P- and B-doped samples. The lines represent least-squares fits to <math display="inline"> <semantics> <mrow> <msub> <mi mathvariant="sans-serif">μ</mi> <mi mathvariant="normal">H</mi> </msub> </mrow> </semantics> </math> (<span class="html-italic">T</span>) ∝ <span class="html-italic">T<sup>n</sup></span>.</p> Full article ">
2041 KiB  
Article
Preparation and Characterization of Zirconia-Coated Nanodiamonds as a Pt Catalyst Support for Methanol Electro-Oxidation
by Jing Lu, Jianbing Zang, Yanhui Wang, Yongchao Xu and Xipeng Xu
Nanomaterials 2016, 6(12), 234; https://doi.org/10.3390/nano6120234 - 2 Dec 2016
Cited by 7 | Viewed by 4647
Abstract
Zirconia-coated nanodiamond (ZrO2/ND) electrode material was successfully prepared by one-step isothermal hydrolyzing from ND-dispersed ZrOCl2·8H2O aqueous solution. High-resolution transmission electron microscopy reveals that a highly conformal and uniform ZrO2 shell was deposited on NDs by this [...] Read more.
Zirconia-coated nanodiamond (ZrO2/ND) electrode material was successfully prepared by one-step isothermal hydrolyzing from ND-dispersed ZrOCl2·8H2O aqueous solution. High-resolution transmission electron microscopy reveals that a highly conformal and uniform ZrO2 shell was deposited on NDs by this simple method. The coating obtained at 90 °C without further calcination was mainly composed of monoclinic nanocrystalline ZrO2 rather than common amorphous Zr(OH)4 clusters. The ZrO2/NDs and pristine ND powder were decorated with platinum (Pt) nanoparticles by electrodeposition from 5 mM chloroplatinic acid solution. The electrochemical studies indicate that Pt/ZrO2/ND catalysts have higher electrocatalytic activity and better stability for methanol oxidation than Pt/ND catalysts in acid. Full article
►▼ Show Figures

Figure 1

Figure 1
<p>Transmission electron microscopy (TEM) (<b>a</b>,<b>c</b>); selected area electron diffraction (SAED) (<b>b</b>); and high-resolution TEM (HRTEM) (<b>d</b>) images of zirconia-coated nanodiamond (ZrO<sub>2</sub>/ND).</p> Full article ">Figure 2
<p>Field emission scanning electron microscope (FESEM) images of ZrO<sub>2</sub>/ND (<b>a</b>); Pt/ZrO<sub>2</sub>/ND (<b>b</b>); and the formation process of Pt/ZrO<sub>2</sub>/ND (<b>c</b>).</p> Full article ">Figure 3
<p>Cyclic voltammetry (CV) curves of Pt/ND (<b>a</b>) and Pt/ZrO<sub>2</sub>/ND (<b>b</b>) electrodes in 0.5 mol/L H<sub>2</sub>SO<sub>4</sub>.</p> Full article ">Figure 4
<p>CV curves of Pt/ND (<b>a</b>) and Pt/ZrO<sub>2</sub>/ND (<b>b</b>) electrodes in 0.5 mol/L CH<sub>3</sub>OH + 0.5 mol/L H<sub>2</sub>SO<sub>4</sub>.</p> Full article ">Figure 5
<p>CV curves of Pt/ND (<b>a</b>) and Pt/ZrO<sub>2</sub>/ND (<b>b</b>) electrodes in 0.5 mol/L CH<sub>3</sub>OH + 0.5 mol/L H<sub>2</sub>SO<sub>4</sub> after 500 cycles.</p> Full article ">
4273 KiB  
Article
Super-Hydrophobic/Icephobic Coatings Based on Silica Nanoparticles Modified by Self-Assembled Monolayers
by Junpeng Liu, Zaid A. Janjua, Martin Roe, Fang Xu, Barbara Turnbull, Kwing-So Choi and Xianghui Hou
Nanomaterials 2016, 6(12), 232; https://doi.org/10.3390/nano6120232 - 2 Dec 2016
Cited by 81 | Viewed by 17646
Abstract
A super-hydrophobic surface has been obtained from nanocomposite materials based on silica nanoparticles and self-assembled monolayers of 1H,1H,2H,2H-perfluorooctyltriethoxysilane (POTS) using spin coating and chemical vapor deposition methods. Scanning electron microscope images reveal the porous structure [...] Read more.
A super-hydrophobic surface has been obtained from nanocomposite materials based on silica nanoparticles and self-assembled monolayers of 1H,1H,2H,2H-perfluorooctyltriethoxysilane (POTS) using spin coating and chemical vapor deposition methods. Scanning electron microscope images reveal the porous structure of the silica nanoparticles, which can trap small-scale air pockets. An average water contact angle of 163° and bouncing off of incoming water droplets suggest that a super-hydrophobic surface has been obtained based on the silica nanoparticles and POTS coating. The monitored water droplet icing test results show that icing is significantly delayed by silica-based nano-coatings compared with bare substrates and commercial icephobic products. Ice adhesion test results show that the ice adhesion strength is reduced remarkably by silica-based nano-coatings. The bouncing phenomenon of water droplets, the icing delay performance and the lower ice adhesion strength suggest that the super-hydrophobic coatings based on a combination of silica and POTS also show icephobicity. An erosion test rig based on pressurized pneumatic water impinging impact was used to evaluate the durability of the super-hydrophobic/icephobic coatings. The results show that durable coatings have been obtained, although improvement will be needed in future work aiming for applications in aerospace. Full article
(This article belongs to the Special Issue Nanocomposite Coatings)
►▼ Show Figures

Figure 1

Figure 1
<p>A schematic diagram of the water impinging test.</p> Full article ">Figure 2
<p>The schematic of the surface modification process by self-assembled monolayers and conversion from hydrophilic (<b>a</b>) to super-hydrophobic (<b>b</b>).</p> Full article ">Figure 3
<p>Scanning electron microscope (SEM) images of silica nanoparticles coating before (<b>a</b>) and after surface treatment (<b>b</b>).</p> Full article ">Figure 4
<p>Energy dispersive X-ray spectroscopy (EDS) results for silica nanoparticles with fluoroalkyl silane, 1<span class="html-italic">H</span>,1<span class="html-italic">H</span>,2<span class="html-italic">H</span>,2<span class="html-italic">H</span>-perfluorooctyltriethoxysilane (POTS) treatment and without treatment.</p> Full article ">Figure 5
<p>X-ray photoelectron spectroscopy (XPS) results for F (<b>a</b>) and C−F (<b>b</b>) of silica nanoparticles with treatment and without treatment by self-assembled monolayers of POTS.</p> Full article ">Figure 6
<p>Fourier transform infrared (FTIR) absorption spectra of silica nanoparticles before and after treatment.</p> Full article ">Figure 7
<p>Water contact angle of water droplets on silica nanoparticles–based coating without (<b>a</b>) and with (<b>b</b>) POTS treatment.</p> Full article ">Figure 8
<p>Water droplet icing test results.</p> Full article ">Figure 9
<p>Ice adhesion results of silica-based nano-coatings on Al substrates (samples 2–7) and untreated Al surface (sample 1).</p> Full article ">Figure 10
<p>Water contact angle before and after erosion test from water impinging for silica-based nano-coatings for as-prepared sample, after 30 min test and after 60 min test.</p> Full article ">
3300 KiB  
Article
Temperature- and Angle-Dependent Magnetic Properties of Ni Nanotube Arrays Fabricated by Electrodeposition in Polycarbonate Templates
by Yonghui Chen, Chen Xu, Yibo Zhou, Khan Maaz, Huijun Yao, Dan Mo, Shuangbao Lyu, Jinglai Duan and Jie Liu
Nanomaterials 2016, 6(12), 231; https://doi.org/10.3390/nano6120231 - 1 Dec 2016
Cited by 11 | Viewed by 4909
Abstract
Parallel arrays of Ni nanotubes with an external diameter of 150 nm, a wall thickness of 15 nm, and a length of 1.2 ± 0.3 µm were successfully fabricated in ion-track etched polycarbonate (PC) templates by electrochemical deposition. The morphology and crystal structure [...] Read more.
Parallel arrays of Ni nanotubes with an external diameter of 150 nm, a wall thickness of 15 nm, and a length of 1.2 ± 0.3 µm were successfully fabricated in ion-track etched polycarbonate (PC) templates by electrochemical deposition. The morphology and crystal structure of the nanotubes were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). Structural analyses indicate that Ni nanotubes have a polycrystalline structure with no preferred orientation. Angle dependent hysteresis studies at room temperature carried out by using a vibrating sample magnetometer (VSM) demonstrate a transition of magnetization between the two different magnetization reversal modes: curling rotation for small angles and coherent rotation for large angles. Furthermore, temperature dependent magnetic analyses performed with a superconducting quantum interference device (SQUID) magnetometer indicate that magnetization of the nanotubes follows modified Bloch’s law in the range 60–300 K, while the deviation of the experimental curve from this law below 60 K can be attributed to the finite size effects in the nanotubes. Finally, it was found that coercivity measured at different temperatures follows Kneller’s law within the premises of Stoner–Wohlfarth model for ferromagnetic nanostructures. Full article
►▼ Show Figures

Figure 1

Figure 1
<p>Scanning electron microscopy (SEM) images of Ni nanotube arrays with (<b>a</b>) low magnification and (<b>b</b>) high magnification; Transmission electron microscopy (TEM) images of a single Ni nanotube with (<b>c</b>) low magnification and (<b>d</b>) high magnification, showing an outer diameter of 150 nm, a wall thickness of 15 nm, and a length of 1.2 ± 0.3 µm. The inset shows the corresponding selected area electron diffraction (SAED) pattern.</p> Full article ">Figure 1 Cont.
<p>Scanning electron microscopy (SEM) images of Ni nanotube arrays with (<b>a</b>) low magnification and (<b>b</b>) high magnification; Transmission electron microscopy (TEM) images of a single Ni nanotube with (<b>c</b>) low magnification and (<b>d</b>) high magnification, showing an outer diameter of 150 nm, a wall thickness of 15 nm, and a length of 1.2 ± 0.3 µm. The inset shows the corresponding selected area electron diffraction (SAED) pattern.</p> Full article ">Figure 2
<p>The X-ray diffraction pattern of Ni nanotubes embedded in polycarbonate (PC) template (<b>a</b>) with (<b>b</b>) JCPDS pattern of the standard Ni is shown for comparison with prepared samples.</p> Full article ">Figure 3
<p>Angular dependence of (<b>a</b>) hysteresis loops (<b>b</b>) coercivity and (<b>c</b>) remanence squareness of Ni nanotube arrays, where θ is the angle between the applied field direction and the tube’s axis.</p> Full article ">Figure 4
<p>Hysteresis loops of Ni nanotubes taken at 5, 20, 40, 60, 100, 150, 200, and 300 K with the field applied parallel to the tube’s axis.</p> Full article ">Figure 5
<p>Temperature-dependent coercivity for Ni nanotubes. The red curve shows the fitting curve according to theoretical model discussed in the text.</p> Full article ">Figure 6
<p>Saturation magnetization as a function of temperature with the red curve representing the modified Bloch’s law.</p> Full article ">
3539 KiB  
Article
Optimum Conditions for the Fabrication of Zein/Ag Composite Nanoparticles from Ethanol/H2O Co-Solvents Using Electrospinning
by Seong Baek Yang, Mohammad Mahbub Rabbani, Byung Chul Ji, Dong-Wook Han, Joon Seok Lee, Jong Won Kim and Jeong Hyun Yeum
Nanomaterials 2016, 6(12), 230; https://doi.org/10.3390/nano6120230 - 1 Dec 2016
Cited by 22 | Viewed by 5421
Abstract
The optimum conditions for the fabrication of zein/Ag composite nanoparticles from ethanol/H2O cosolvents using electrospinning and the properties of the composite were investigated. The zein/Ag nanoparticles were characterized using field-emission scanning electron microscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), and [...] Read more.
The optimum conditions for the fabrication of zein/Ag composite nanoparticles from ethanol/H2O cosolvents using electrospinning and the properties of the composite were investigated. The zein/Ag nanoparticles were characterized using field-emission scanning electron microscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), and thermogravimetric analysis. The antibacterial activity of the zein/Ag composite nanoparticles was also investigated. The XRD patterns and TEM images indicate the coexistence of a zein matrix and well-distributed Ag nanoparticles. Full article
►▼ Show Figures

Figure 1

Figure 1
<p>Field emission scanning electron microscopy (FE-SEM) images of zein nanomaterials electrospun from ethanol aqueous solutions with ethanol/water ratios of 7/3, 8/2 and 9/1 (<span class="html-italic">v/v</span>) at polymer concentrations of 10, 15 and 20 wt % (Tip-to-collector distance (TCD) = 15 cm and applied voltage = 15 kV).</p> Full article ">Figure 2
<p>FE-SEM images, average diameter, and distribution of zein/Ag nanoparticles electrospun from ethanol aqueous solutions with an ethanol/water ratio of 8/2 (<span class="html-italic">v</span>/<span class="html-italic">v</span>) at Ag concentrations of (<b>a</b>) 0, (<b>b</b>) 2 and (<b>c</b>) 4 wt % (polymer concentration = 10 wt %, TCD = 15 cm, and applied voltage = 15 kV).</p> Full article ">Figure 3
<p>Transmission electron microscopy images of zein/Ag nanoparticles electrospun from ethanol aqueous solutions with an ethanol/water ratio of 8/2 (<span class="html-italic">v/v</span>) at Ag concentrations of (<b>a</b>) 0, (<b>b</b>) 2 and (<b>c</b>) 4 wt % (polymer concentration = 10 wt %, TCD = 15 cm, and applied voltage = 15 kV).</p> Full article ">Figure 4
<p>X-ray diffraction patterns of zein/Ag nanoparticles electrospun from ethanol aqueous solutions with an ethanol/water ratio of 8/2 (<span class="html-italic">v/v</span>) at Ag concentrations of (<b>a</b>) 0, (<b>b</b>) 2 and (<b>c</b>) 4 wt % (polymer concentration = 10 wt %, TCD = 15 cm, and applied voltage = 15 kV).</p> Full article ">Figure 5
<p>Thermogravimetric analysis data of zein/Ag nanoparticles electrospun from ethanol aqueous solutions with an ethanol/water ratio of 8/2 (<span class="html-italic">v/v</span>) at Ag concentrations of (<b>a</b>) 0, (<b>b</b>) 2 and (<b>c</b>) 4 wt % (polymer concentration = 10 wt %, TCD = 15 cm, and applied voltage = 15 kV).</p> Full article ">Figure 6
<p>Antibacterial ability against <span class="html-italic">Staphylococcus aureus</span>. (<b>a</b>) blank and with zein/Ag nanoparticles containing Ag concentrations of (<b>b</b>) 0 wt %; (<b>c</b>) 2 wt %; and (<b>d</b>) 4 wt % (after one week).</p> Full article ">Figure 7
<p>Preservation performance of zein/Ag nanoparticles prepared with different Ag concentrations of 0, 2 and 4 wt %.</p> Full article ">Figure 8
<p>Ag<sup>+</sup> release from zein/Ag nanopartilces for different periods of time. The concentration of incorporated Ag nanoparticle in zein were 2 wt % and 4 wt %.</p> Full article ">
2250 KiB  
Communication
The Assembly of DNA Amphiphiles at Liquid Crystal-Aqueous Interface
by Jingsheng Zhou, Yuanchen Dong, Yiyang Zhang, Dongsheng Liu and Zhongqiang Yang
Nanomaterials 2016, 6(12), 229; https://doi.org/10.3390/nano6120229 - 1 Dec 2016
Cited by 19 | Viewed by 5196
Abstract
In this article, we synthesized a type of DNA amphiphiles (called DNA-lipids) and systematically studied its assembly behavior at the liquid crystal (LC)—aqueous interface. It turned out that the pure DNA-lipids at various concentrations cannot trigger the optical transition of liquid crystals from [...] Read more.
In this article, we synthesized a type of DNA amphiphiles (called DNA-lipids) and systematically studied its assembly behavior at the liquid crystal (LC)—aqueous interface. It turned out that the pure DNA-lipids at various concentrations cannot trigger the optical transition of liquid crystals from planar anchoring to homeotropic anchoring at the liquid crystal—aqueous interface. The co-assembly of DNA-lipid and l-dilauroyl phosphatidylcholine (l-DLPC) indicated that the DLPC assembled all over the LC-aqueous interface, and DNA-lipids prefer to couple with LC in certain areas, particularly in polarized and fluorescent image, forming micron sized net-like structures. The addition of DNA complementary to DNA-lipids forming double stranded DNA-lipids caused de-assembly of DNA-lipids from LC-aqueous interface, resulting in the disappearance of net-like structures, which can be visualized through polarized microscope. The optical changes combined with DNA unique designable property and specific interaction with wide range of target molecules, the DNA-lipids decorated LC-aqueous interface would provide a new platform for biological sensing and diagnosis. Full article
(This article belongs to the Special Issue DNA-Based Nanotechnology)
►▼ Show Figures

Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>(<b>A</b>) Optical images (transmission through crossed polars) of 5CB before and (<b>B</b>) after exposure to aqueous (phosphate buffer saline (PBS)) dispersions of 20 μM DNA-lipids for 1 h (magnified image); (<b>C</b>) Optical images of 5CB exposure to aqueous dispersions of 5 μM <span class="html-small-caps">l</span>-DLPC for 1 h and (<b>D</b>) magnified image; (<b>E</b>) Optical images of 5CB exposure to aqueous dispersions of 20 μM DNA-lipids and 5 μM <span class="html-small-caps">l</span>-DLPC for 1 h and (<b>F</b>) magnified image.</p> Full article ">Figure 2
<p>(<b>A</b>) Optical images (crossed polars) and (<b>B</b>) corresponding green fluorescence micrographs and (<b>C</b>) corresponding red fluorescence micrographs of LC-aqueous interface exposure to a mixture of 20 μM DNA-lipids, 5 μM <span class="html-small-caps">l</span>-DLPC and 0.5 μM Rh-DHPE for 1 h then introduction of 1× SYBR Green; (<b>D</b>) Overlaid images of (<b>B</b>,<b>C</b>); (<b>E</b>–<b>G</b>) Magnified image of (<b>A</b>–<b>C</b>); (<b>H</b>) Overlaid images of (<b>F</b>,<b>G</b>).</p> Full article ">Figure 3
<p>(<b>A</b>) Optical images (crossed polars) and (<b>B</b>) corresponding fluorescence micrographs of LC-aqueous interface decorated with DNA-lipids and <span class="html-small-caps">l</span>-DLPC, and dyed by SYBR Green; (<b>C</b>) Optical images and (<b>D</b>) corresponding fluorescence micrographs after the introduction of 20 μM c-DNA of DNA-lipids for 3 min in (<b>A</b>).</p> Full article ">Figure 4
<p>(<b>A</b>) Optical images (crossed polars) and (<b>B</b>) corresponding fluorescence micrographs of LC-aqueous interface decorated with DNA-lipids and <span class="html-small-caps">l</span>-DLPC, and dyed by SYBR Green; (<b>C</b>) Optical images and (<b>D</b>) corresponding fluorescence micrographs after the introduction of 20 μM random DNA strands for 10 min in (<b>A</b>); (<b>E</b>) Optical images and (<b>F</b>) corresponding fluorescence micrographs after the introduction of 20 μM c-DNA of DNA-lipids for 3 min in (<b>C</b>).</p> Full article ">Figure 5
<p>The schematic illustration of the LC-aqueous interface decorated with DNA-lipids and <span class="html-small-caps">l</span>-DLPC, (<b>A</b>) before and (<b>B</b>) after addition of its complementary DNA strands, c-DNA. (<b>C</b>) DNA-lipids hybridize with c-DNA to form double strands and disassemble from the LC-aqueous interface.</p> Full article ">Figure 6
<p>Optical images (crossed polars) of 5CB exposure to a mixture of 20 μM DNA-lipids, 20 μM c-DNA and 5 μM <span class="html-small-caps">l</span>-DLPC for 1 h.</p> Full article ">
7653 KiB  
Article
Refinement of Magnetite Nanoparticles by Coating with Organic Stabilizers
by Monica Cîrcu, Alexandrina Nan, Gheorghe Borodi, Jürgen Liebscher and Rodica Turcu
Nanomaterials 2016, 6(12), 228; https://doi.org/10.3390/nano6120228 - 29 Nov 2016
Cited by 36 | Viewed by 6600
Abstract
Magnetite nanoparticles are of great importance in nanotechnology and nanomedicine and have found manifold applications. Here, the effect of coating of magnetite nanoparticles with organic stabilizers, such as O-phosphoryl ethanolamine, glycerol phosphate, phospho-l-ascorbic acid, phospho-d,l-serine, glycolic [...] Read more.
Magnetite nanoparticles are of great importance in nanotechnology and nanomedicine and have found manifold applications. Here, the effect of coating of magnetite nanoparticles with organic stabilizers, such as O-phosphoryl ethanolamine, glycerol phosphate, phospho-l-ascorbic acid, phospho-d,l-serine, glycolic acid, lactic acid, d,l-malic acid, and d,l-mandelic acid was studied. Remarkably, this procedure led to an improvement of saturation magnetization in three cases rather than to an unfavorable decrease as usually observed. Detailed X-ray powder diffraction investigations revealed that changes in the average crystallite occurred in the coating process. Surprisingly, changes of the average crystallite sizes in either direction were further observed, when the exposure time to the stabilizer was increased. These results imply a new mechanism for the well-known coating of magnetite nanoparticles with stabilizers. Instead of the hitherto accepted simple anchoring of the stabilizers to the magnetite nanoparticle surfaces, a more complex recrystallization mechanism is likely, wherein partial re-dispersion of magnetite moieties from the nanoparticles and re-deposition are involved. The results can help producers and users of magnetite nanoparticles to obtain optimal results in the production of core shell magnetite nanoparticles. Full article
►▼ Show Figures

Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Fourier transform infrared spectroscopy (FTIR) spectrum of <b>3b</b> (Fe<sub>3</sub>O<sub>4</sub> covered with glycerol phosphate); inset shows an amplified region between 800 and 1200 cm<sup>−1</sup>.</p> Full article ">Figure 2
<p>Magnetization versus applied magnetic field of magnetic nanoparticles (MNPs) at room temperature: (<b>a</b>) <b>3a</b>-3 h, <b>3a</b>-24 h; (<b>b</b>) <b>3e</b>-3 h, <b>3e</b>-24 h.</p> Full article ">Figure 2 Cont.
<p>Magnetization versus applied magnetic field of magnetic nanoparticles (MNPs) at room temperature: (<b>a</b>) <b>3a</b>-3 h, <b>3a</b>-24 h; (<b>b</b>) <b>3e</b>-3 h, <b>3e</b>-24 h.</p> Full article ">Figure 3
<p>High resolution X-ray photoelectron spectroscopy XPS spectra of (<b>a</b>) Fe2p, (<b>b</b>) P2p, (<b>c</b>) C1s, (<b>d</b>) N1s, (<b>e</b>) O1s core-levels of magnetic nanoparticles <b>3a</b>-3 h.</p> Full article ">Figure 4
<p>Transmission electron microscopy (TEM) images of magnetic nanoparticles <b>3a</b>-3 h (<b>a</b>) and MNP <b>2h</b>-3 h (<b>b</b>).</p> Full article ">Figure 5
<p>X-ray powder diffraction (XRPD) patterns of magnetic nanoparticles <b>3a</b>-24 h, <b>3a</b>-3 h, <b>1</b> and <b>3e</b>-24 h.</p> Full article ">Scheme 1
<p>Coating of magnetic nanoparticles <b>1</b> with stabilizers <b>2</b> to magnetic naoparticles <b>3</b>.</p> Full article ">Scheme 2
<p>Mechanisms of coating magnetic nanoparticles <b>1</b> with stabilizers <b>2</b>.</p> Full article ">
6669 KiB  
Article
Influence of External Gaseous Environments on the Electrical Properties of ZnO Nanostructures Obtained by a Hydrothermal Method
by Marcin Procek, Tadeusz Pustelny and Agnieszka Stolarczyk
Nanomaterials 2016, 6(12), 227; https://doi.org/10.3390/nano6120227 - 29 Nov 2016
Cited by 30 | Viewed by 5214
Abstract
This paper deals with experimental investigations of ZnO nanostructures, consisting of a mixture of nanoparticles and nanowires, obtained by the chemical (hydrothermal) method. The influences of both oxidizing (NO2) and reducing gases (H2, NH3), as well as [...] Read more.
This paper deals with experimental investigations of ZnO nanostructures, consisting of a mixture of nanoparticles and nanowires, obtained by the chemical (hydrothermal) method. The influences of both oxidizing (NO2) and reducing gases (H2, NH3), as well as relative humidity (RH) on the physical and chemical properties of ZnO nanostructures were tested. Carrier gas effect on the structure interaction with gases was also tested; experiments were conducted in air and nitrogen (N2) atmospheres. The effect of investigated gases on the resistance of the ZnO nanostructures was tested over a wide range of concentrations at room temperature (RT) and at 200 °C. The impact of near- ultraviolet (UV) excitation (λ = 390 nm) at RT was also studied. These investigations indicated a high response of ZnO nanostructures to small concentrations of NO2. The structure responses to 1 ppm of NO2 amounted to about: 600% in N2/230% in air at 200 °C (in dark conditions) and 430% in N2/340% in air at RT (with UV excitation). The response of the structure to the effect of NO2 at 200 °C is more than 105 times greater than the response to NH3, and more than 106 times greater than that to H2 in the relation of 1 ppm. Thus the selectivity of the structure for NO2 is very good. What is more, the selectivity to NO2 at RT with UV excitation increases in comparison at elevated temperature. This paper presents a great potential for practical applications of ZnO nanostructures (including nanoparticles) in resistive NO2 sensors. Full article
(This article belongs to the Special Issue Semiconductor Nanoparticles for Electric Device Applications)
►▼ Show Figures

Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Scheme of (<b>a</b>) the measurement stand and (<b>b</b>) the measurement chamber.</p> Full article ">Figure 2
<p>Field emission scanning electron microscope (FE-SEM) image of the ZnO nanostructures (magnification 20,000× and 50,000×).</p> Full article ">Figure 3
<p>X-ray powder diffraction (XRD) patterns of ZnO nanostructures (λ = 0.179 nm).</p> Full article ">Figure 4
<p>Raman spectrum of ZnO nanostructures.</p> Full article ">Figure 5
<p>Scanning electron microscope (SEM) image of the distribution of ZnO nanostructures on the interdigital transducer.</p> Full article ">Figure 6
<p>The dependence of the resistance of ZnO nanostructures on the wavelength.</p> Full article ">Figure 7
<p>Dependence of the resistance of the structure based on ZnO nanoparticles on temperature in: synthetic air and in nitrogen (gas flow = 500 mL/min., <span class="html-italic">RH</span> = 6%).</p> Full article ">Figure 8
<p>The reaction of ZnO nanostructures to NO<sub>2</sub> in the atmospheres of synthetic air and nitrogen at: (<b>a</b>) RT; (<b>b</b>) elevated temperature of 200 °C.</p> Full article ">Figure 9
<p>The response of the ZnO nanostructures to the effect of NO<sub>2</sub> and ultraviolet (UV) irradiation in atmospheres of air and nitrogen at RT.</p> Full article ">Figure 10
<p>Reaction of the ZnO nanostructures with H<sub>2</sub> in the atmosphere of synthetic air and nitrogen at: (<b>a</b>) RT; (<b>b</b>) temperature of 200 °C.</p> Full article ">Figure 11
<p>Response of the ZnO nanostructures to H<sub>2</sub> and at UV irradiation under atmospheres of air and nitrogen at RT.</p> Full article ">Figure 12
<p>Reactions of the ZnO nanostructures with NH<sub>3</sub> in air and nitrogen atmospheres at: (<b>a</b>) RT; (<b>b</b>) 200 °C.</p> Full article ">Figure 13
<p>The response of the ZnO nanostructures to NH<sub>3</sub> under continuous UV irradiation under atmospheres of air and nitrogen at RT (23 °C).</p> Full article ">Figure 14
<p>Reaction of the ZnO nanostructures to changes of the relative humidity (RH) level under atmospheres of nitrogen and air at: (<b>a</b>) RT; (<b>b</b>) 200 °C.</p> Full article ">Figure 15
<p>Responses of the ZnO nanostructures to RH changes under UV irradiation under atmospheres of air and nitrogen at RT (23 °C).</p> Full article ">Figure 16
<p>Comparison of the sensitivity of ZnO nanostructures to the action of selected gases.</p> Full article ">
2838 KiB  
Article
The Chemical Deposition Method for the Decoration of Palladium Particles on Carbon Nanofibers with Rapid Conductivity Changes
by Hoik Lee, Duy-Nam Phan, Myungwoong Kim, Daewon Sohn, Seong-Geun Oh, Seong Hun Kim and Ick Soo Kim
Nanomaterials 2016, 6(12), 226; https://doi.org/10.3390/nano6120226 - 29 Nov 2016
Cited by 14 | Viewed by 5202
Abstract
Palladium (Pd) metal is well-known for hydrogen sensing material due to its high sensitivity and selectivity toward hydrogen, and is able to detect hydrogen at near room temperature. In this work, palladium-doped carbon nanofibers (Pd/CNFs) were successfully produced in a facile manner via [...] Read more.
Palladium (Pd) metal is well-known for hydrogen sensing material due to its high sensitivity and selectivity toward hydrogen, and is able to detect hydrogen at near room temperature. In this work, palladium-doped carbon nanofibers (Pd/CNFs) were successfully produced in a facile manner via electrospinning. Well-organized and uniformly distributed Pd was observed in microscopic images of the resultant nanofibers. Hydrogen causes an increment in the volume of Pd due to the ability of hydrogen atoms to occupy the octahedral interstitial positions within its face centered cubic lattice structure, resulting in the resistance transition of Pd/CNFs. The resistance variation was around 400%, and it responded rapidly within 1 min, even in 5% hydrogen atmosphere conditions at room temperature. This fibrous hybrid material platform will open a new and practical route and stimulate further researches on the development of hydrogen sensing materials with rapid response, even to low concentrations of hydrogen in an atmosphere. Full article
►▼ Show Figures

Figure 1

Figure 1
<p>Morphology change of CNFs (carbon nanofibers) through chemical deposition in different pH solutions: (<b>a</b>) virgin CNFs; (<b>b</b>) pH 1; (<b>c</b>) pH 3; (<b>d</b>) pH 5; (<b>e</b>) pH 7; (<b>f</b>) pH 10.</p> Full article ">Figure 2
<p>Scanning electron microscope (SEM) images of chemically deposited Pd ions on CNFs with different times: (<b>a</b>) 1 h; (<b>b</b>) 6 h; (<b>c</b>) 12 h. The images are accompanied by the corresponding diameter distributions in (<b>d</b>–<b>f</b>).</p> Full article ">Figure 3
<p>Probing Pd decoration process on CNFs. (<b>a</b>) The X-ray photoelectron spectroscopy (XPS) spectra of CNFs and Pd/CNFs with different deposition times. Inserted spectra magnified in Pd 3d peaks of Pd/CNFs; (<b>b</b>) elemental analysis conducted by energy dispersive X-ray (EDX) shows an increment in Pd content in CNFs as deposition time increases.</p> Full article ">Figure 4
<p>Magnified Pd/CNFs with different deposition time (<b>a</b>,<b>b</b>) 1 h; (<b>c</b>,<b>d</b>) 6 h; (<b>e</b>,<b>f</b>) 12 h is presented. The morphology changes are shown (<b>a</b>,<b>c</b>,<b>e</b>) before and (<b>b</b>,<b>d</b>,<b>f</b>) after hydrogen adsorption.</p> Full article ">Figure 5
<p>Electro-resistance behavior upon hydrogen adsorption. (<b>a</b>) The calculated electric-resistance variation rate (Δ<span class="html-italic">R</span>%) with variation in deposition time and (<b>b</b>) with different hydrogen concentrations, from 5% (<b>black</b>), 10% (<b>red</b>), 20% (<b>blue</b>), and 50% (<b>green</b>).</p> Full article ">
3601 KiB  
Article
Titanium Dioxide Nanoparticle-Biomolecule Interactions Influence Oral Absorption
by Mi-Rae Jo, Jin Yu, Hyoung-Jun Kim, Jae Ho Song, Kyoung-Min Kim, Jae-Min Oh and Soo-Jin Choi
Nanomaterials 2016, 6(12), 225; https://doi.org/10.3390/nano6120225 - 29 Nov 2016
Cited by 38 | Viewed by 6017
Abstract
Titanium dioxide (TiO2) nanoparticles (NPs) have been widely applied in various industrial fields, such as electronics, packaging, food, and cosmetics. Accordingly, concerns about the potential toxicity of TiO2 NPs have increased. In order to comprehend their in vivo behavior and [...] Read more.
Titanium dioxide (TiO2) nanoparticles (NPs) have been widely applied in various industrial fields, such as electronics, packaging, food, and cosmetics. Accordingly, concerns about the potential toxicity of TiO2 NPs have increased. In order to comprehend their in vivo behavior and potential toxicity, we must evaluate the interactions between TiO2 NPs and biomolecules, which can alter the physicochemical properties and the fate of NPs under physiological conditions. In the present study, in vivo solubility, oral absorption, tissue distribution, and excretion kinetics of food grade TiO2 (f-TiO2) NPs were evaluated following a single-dose oral administration to rats and were compared to those of general grade TiO2 (g-TiO2) NPs. The effect of the interactions between the TiO2 NPs and biomolecules, such as glucose and albumin, on oral absorption was also investigated, with the aim of determining the surface interactions between them. The intestinal transport pathway was also assessed using 3-dimensional culture systems. The results demonstrate that slightly higher oral absorption of f-TiO2 NPs compared to g-TiO2 NPs could be related to their intestinal transport mechanism by microfold (M) cells, however, most of the NPs were eliminated through the feces. Moreover, the biokinetics of f-TiO2 NPs was highly dependent on their interaction with biomolecules, and the dispersibility was affected by modified surface chemistry. Full article
(This article belongs to the Special Issue Cytotoxicity of Nanoparticles)
►▼ Show Figures

Figure 1

Figure 1
<p>Powder X-ray diffraction patterns of (<b>A</b>) food grade TiO<sub>2</sub> (f-TiO<sub>2</sub>) and (<b>B</b>) general grade TiO<sub>2</sub> (g-TiO<sub>2</sub>). Scanning electron microscopic images and corresponding size distribution histograms of (<b>C</b>) f-TiO<sub>2</sub> and (<b>D</b>) g-TiO<sub>2</sub>.</p> Full article ">Figure 2
<p>Time-dependent changes in colloidal properties. (<b>A</b>) Zeta potential; (<b>B</b>) hydrodynamic diameter; and (<b>C</b>) polydispersity index (PDI) values (PDI = [(standard deviation)/(average diameter)]<sup>2</sup>). Squares, f-TiO<sub>2</sub>; circles, g-TiO<sub>2</sub>; closed symbols, 1% glucose; open symbols, 1% albumin (□, f-TiO<sub>2</sub> in 1% albumin; ■: f-TiO<sub>2</sub> in 1% glucose; ○: g-TiO<sub>2</sub> in 1% albumin; ●: g-TiO<sub>2</sub> in 1% glucose). Data points at time 0 are the zeta potentials of each material in water without albumin or glucose.</p> Full article ">Figure 3
<p>Powder X-ray diffraction patterns of (<b>A</b>) f-TiO<sub>2</sub> and (<b>B</b>) g-TiO<sub>2</sub> with or without biomolecules. X-ray photoelectron spectra of (<b>C</b>) f-TiO<sub>2</sub> and (<b>D</b>) g-TiO<sub>2</sub> with or without biomolecules. (a) TiO<sub>2</sub> alone; (b) in 1% albumin; and (c) in 1% glucose.</p> Full article ">Figure 4
<p>Intestinal transport mechanism of TiO<sub>2</sub> NPs in vitro in a human follicle-associated epithelium (FAE) model. The transcytosis mechanism of particle transport was assessed by comparing transported amounts at 4 °C and 37 °C (<b>A</b>) and in the presence or absence of ethylene glycol tetraacetic acid (EGTA) at 37 °C (<b>B</b>). Mean values with different superscripts (A,B) for the same type of NP indicate significant differences at 4 °C and 37 °C (<span class="html-italic">p</span> &lt; 0.05). Mean values with different superscripts (a,b) in the same figure indicate significant differences among the control (cells in medium), f-TiO<sub>2</sub>-, and g-TiO<sub>2</sub>-treated groups (<span class="html-italic">p</span> &lt; 0.05).</p> Full article ">Figure 5
<p>Effect of the presence of albumin or glucose on the plasma concentration-time profiles of f-TiO<sub>2</sub> NPs after orally administering a single-dose (500 mg/kg) to rats. D.W., distilled water.</p> Full article ">Figure 6
<p>Plasma concentration-time profiles of the two kinds of TiO<sub>2</sub> NPs after orally administering a single-dose (500 mg/kg) to rats.</p> Full article ">Figure 7
<p>Tissue distribution of (<b>A</b>) f-TiO<sub>2</sub> and (<b>B</b>) g-TiO<sub>2</sub> after orally administering a single-dose (500 mg/kg) to rats. Mean values with different superscripts (a,b) in the same organs indicate significant differences between control and particle-treated animals (<span class="html-italic">p</span> &lt; 0.05).</p> Full article ">Figure 8
<p>Excretion kinetics of f-TiO<sub>2</sub> and g-TiO<sub>2</sub> via (<b>A</b>) urine and (<b>B</b>) feces after orally administering a single-dose (500 mg/kg) to rats. Mean values with different superscripts (a,b) at the same time points indicate significant differences between the control and particle-treated rats (<span class="html-italic">p</span> &lt; 0.05).</p> Full article ">
1677 KiB  
Review
Nano-Biosensor for Monitoring the Neural Differentiation of Stem Cells
by Jin-Ho Lee, Taek Lee and Jeong-Woo Choi
Nanomaterials 2016, 6(12), 224; https://doi.org/10.3390/nano6120224 - 28 Nov 2016
Cited by 20 | Viewed by 5890
Abstract
In tissue engineering and regenerative medicine, monitoring the status of stem cell differentiation is crucial to verify therapeutic efficacy and optimize treatment procedures. However, traditional methods, such as cell staining and sorting, are labor-intensive and may damage the cells. Therefore, the development of [...] Read more.
In tissue engineering and regenerative medicine, monitoring the status of stem cell differentiation is crucial to verify therapeutic efficacy and optimize treatment procedures. However, traditional methods, such as cell staining and sorting, are labor-intensive and may damage the cells. Therefore, the development of noninvasive methods to monitor the differentiation status in situ is highly desirable and can be of great benefit to stem cell-based therapies. Toward this end, nanotechnology has been applied to develop highly-sensitive biosensors to noninvasively monitor the neural differentiation of stem cells. Herein, this article reviews the development of noninvasive nano-biosensor systems to monitor the neural differentiation of stem cells, mainly focusing on optical (plasmonic) and eletrochemical methods. The findings in this review suggest that novel nano-biosensors capable of monitoring stem cell differentiation are a promising type of technology that can accelerate the development of stem cell therapies, including regenerative medicine. Full article
(This article belongs to the Special Issue Nanostructured Biosensors 2016)
►▼ Show Figures

Figure 1

Figure 1
<p>(<b>a</b>) Scanning Electron Microscopy (SEM) image of a nanoporous gold film (NPGF)-based electrode surface. Differential pulse voltammetry (DPV) results for (<b>b</b>) a mixture of ascorbic acid (AA) and dopamine (DA) at (solid line) bare Au and (dashed line) NPGF electrode; (<b>c</b>) Varying concentrations of DA (0.1–40 μM) in the presence of AA (5 μM). Inset: Linear plot of the anodic current peak as a function of the DA concentration (<b>d</b>) varying concentrations of AA (10–40 μM) in the presence of DA (5 μM). Inset: Linear plot of anodic current peak as a function of AA concentration; (<b>e</b>) Varying concentrations of DA in the presence of uric acid (UA) (500 μM). Inset: Linear plot of anodic current peak as a function of DA concentration; (<b>f</b>) Varying concentrations of DA in the presence of AA (5 μM) and UA (1 mM). Inset: Linear plot of anodic current peak as a function of DA concentration; (<b>g</b>) Anodic current peak corresponding to oxidation of varying concentrations of DA (0.1–20 μM) in the presence of AA (5 μM) and UA (0.5 mM) in both human serum and phosphate buffered saline (PBS) buffer. (Modified from Ref. [<a href="#B29-nanomaterials-06-00224" class="html-bibr">29</a>] with permission, Copyright 2010 Elsevier (Amsterdam, The Netherlands)).</p> Full article ">Figure 2
<p>(<b>a</b>) Schematic diagram depicting the conversion of human neural stem cells (hNSCs) into dopaminergic (DAergic) and non-DAergic neurons; (<b>b</b>) The oxidation peak intensities of dopamine obtained from the CV with various electrodes (Student’s <span class="html-italic">t</span>-test, <span class="html-italic">N</span> = 3, * <span class="html-italic">p</span> &lt; 0.05, ** <span class="html-italic">p</span> &lt; 0.01, *** <span class="html-italic">p</span> &lt; 0.001) (<b>c</b>) Cyclic voltammogram obtained from cells undergoing differentiation into DAergic Neurons. The result only show completely matured DAergic neurons that reveal clear redox peaks compared to hNSCs, neurospheres, and premature neurons; (<b>d</b>) Oxidation peak intensities obtained from (<b>c</b>) and other types of cells (astrocytes and fibroblasts) (Modified from Ref. [<a href="#B33-nanomaterials-06-00224" class="html-bibr">33</a>] with permission, Copyright 2015 WIELY-VCH Verlag GmbH, Berlin, Germany).</p> Full article ">Figure 3
<p>(<b>a</b>) Schematic diagram representing the method to detect the undifferentiated and differentiated state of the mouse neural stem cells (NSCs) using 3D GO-encapsulated gold nanoparticles. Raman spectra of (Full-size image (2 K)) undifferentiated or (Full-size image (2 K) differentiated mNSCs on (<b>b</b>) Substrate A: indium tin oxide (ITO); (<b>c</b>) Substrate B: GO coated ITO; (<b>d</b>) Substrate C: AuNP coated ITO and (<b>e</b>) Substrate D: GO-encapsulated AuNP coated ITO; (<b>f</b>) Confocal fluorescence images of differentiated mNSCs on Substrate D showing the successful differentiation of mNSCs to neuronal cells; (<b>g</b>) Intensity difference of Raman peaks at 1656 cm<sup>−1</sup> (C double bond; length as m-dashC bond) achieved from undifferentiated mNSCs subtracted by differentiated cells († <span class="html-italic">p</span> &lt; 0.05, <span class="html-italic">N</span> = 3, ANOVA test and * <span class="html-italic">p</span> &lt; 0.05, Student’s <span class="html-italic">t</span>-test); (<b>h</b>) Relative values of the Raman intensity at 1656 cm<sup>−1</sup> divided by the intensity at 1470 cm<sup>−1</sup>. All the Raman spectra of the mNSCs were subtracted by the Raman spectra of the same substrates without cells to eliminate the background signals. The results are the medians of the Raman signals obtained from ten different spots. (Modified from Ref. [<a href="#B24-nanomaterials-06-00224" class="html-bibr">24</a>] with permission, Copyright 2013 Elsevier).</p> Full article ">Figure 4
<p>(<b>a</b>) Schematic diagram showing the spectro-electrochemical-based neural stem cell differentiation monitoring sensor on a gold nanostar array; (<b>b</b>) Raman spectrum for (1) undifferentiated and (2) differentiated HB1.F3 cells within the range of 600 cm<sup>−1</sup> to 1750 cm<sup>−1</sup>; (<b>c</b>) cyclic voltamogram for differentiated and undifferentiated HB1.F3 cells. (Modified from Ref. [<a href="#B52-nanomaterials-06-00224" class="html-bibr">52</a>] with permission, Copyright 2015 The Royal Society of Chemistry, London, UK).</p> Full article ">
2733 KiB  
Article
Modified Nanoemulsions with Iron Oxide for Magnetic Resonance Imaging
by Yongyi Fan, Rui Guo, Xiangyang Shi, Steven Allen, Zhengyi Cao, James R. Baker and Su He Wang
Nanomaterials 2016, 6(12), 223; https://doi.org/10.3390/nano6120223 - 25 Nov 2016
Cited by 9 | Viewed by 4633
Abstract
A nanoemulsion (NE) is a surfactant-based, oil-in-water, nanoscale, high-energy emulsion with a mean droplet diameter of 400–600 nm. When mixed with antigen and applied nasally, a NE acts as a mucosal adjuvant and induces mucosal immune responses. One possible mechanism for the adjuvant [...] Read more.
A nanoemulsion (NE) is a surfactant-based, oil-in-water, nanoscale, high-energy emulsion with a mean droplet diameter of 400–600 nm. When mixed with antigen and applied nasally, a NE acts as a mucosal adjuvant and induces mucosal immune responses. One possible mechanism for the adjuvant effect of this material is that it augments antigen uptake and distribution to lymphoid tissues, where the immune response is generated. Biocompatible iron oxide nanoparticles have been used as a unique imaging approach to study the dynamics of cells or molecular migration. To study the uptake of NEs and track them in vivo, iron oxide nanoparticles were synthesized and dispersed in soybean oil to make iron oxide-modified NEs. Our results show that iron oxide nanoparticles can be stabilized in the oil phase of the nanoemulsion at a concentration of 30 µg/μL and the iron oxide-modified NEs have a mean diameter of 521 nm. In vitro experiments demonstrated that iron oxide-modified NEs can affect uptake by TC-1 cells (a murine epithelial cell line) and reduce the intensity of magnetic resonance (MR) images by shortening the T2 time. Most importantly, in vivo studies demonstrated that iron oxide-modified NE could be detected in mouse nasal septum by both transmission electron microscopy and MR imaging. Altogether these experiments demonstrate that iron oxide-modified NE is a unique tool that can be used to study uptake and distribution of NEs after nasal application. Full article
►▼ Show Figures

Figure 1

Figure 1
<p>(<b>a</b>) Transmission electron micrograph; (<b>b</b>) High-resolution transmission electron micrograph; (<b>c</b>) Selected area electron diffraction pattern of Fe<sub>3</sub>O<sub>4</sub> nanoparticles.</p> Full article ">Figure 2
<p>TEM images of iron oxide-modified NE in histo-gel at (<b>a</b>) 19,000×; and (<b>b</b>) 130,000×.</p> Full article ">Figure 3
<p>2,3-Bis-(2-methoxy-4-nitro-5-sulfophenyl)-2<span class="html-italic">H</span>-tetrazolium-5-carboxanilide (XTT) viability assay of TC-1 cells treated with Fe<sub>3</sub>O<sub>4</sub> modified NEs at Fe concentration of 0<span class="html-italic">–</span>0.8 mM for 15 min. TC-1 cells treated with phosphate-buffered saline (PBS) were used as control.</p> Full article ">Figure 4
<p>The 1/T2 value of TC-1 cells after treated with PBS, Fe<sub>3</sub>O<sub>4</sub> modified NEs at different Fe concentrations for 15 min.</p> Full article ">Figure 5
<p>Nasal epithelia structure following the administration of NE and iron oxide-modified NE by TEM. (<b>a</b>) Nasal septa from mice treated with NE alone; (<b>b</b>) nasal septa from mice treated with iron oxide modified NE; (<b>c</b>) nasal septa from mice treated with iron oxide modified NE at the higher resolution.</p> Full article ">Figure 6
<p>MRI tracking of iron oxide-modified NE in mice. MR images of a mouse sinus both before the administration of iron oxide-modified NE (<b>a</b>) and 15–30 min after administration (<b>b</b>). The relative loss in image intensity in the sinuses (arrows) from (<b>a</b>) to (<b>b</b>) is due to an increase in the T2* signal decay rate constant of the sinus. This is thought to be facilitated by the increased concentration of iron in the sinus. The T2* constant for the sinuses is measured to be 8.5 ms before administration 4.4 ms after administration (<span class="html-italic">p</span> &lt; 0.05).</p> Full article ">Scheme 1
<p>Schematic illustration of the synthesis of iron oxide-modified nanoemulsions (NEs).</p> Full article ">
1838 KiB  
Article
Shape and Charge of Gold Nanomaterials Influence Survivorship, Oxidative Stress and Moulting of Daphnia magna
by Fatima Nasser, Adam Davis, Eugenia Valsami-Jones and Iseult Lynch
Nanomaterials 2016, 6(12), 222; https://doi.org/10.3390/nano6120222 - 25 Nov 2016
Cited by 33 | Viewed by 6529
Abstract
Engineered nanomaterials (ENMs) are materials with at least one dimension between 1–100 nm. The small size of ENMs results in a large surface area to volume ratio, giving ENMs novel characteristics that are not traditionally exhibited by larger bulk materials. Coupled with large [...] Read more.
Engineered nanomaterials (ENMs) are materials with at least one dimension between 1–100 nm. The small size of ENMs results in a large surface area to volume ratio, giving ENMs novel characteristics that are not traditionally exhibited by larger bulk materials. Coupled with large surface area is an enormous capacity for surface functionalization of ENMs, e.g., with different ligands or surface changes, leading to an almost infinite array of variability of ENMs. Here we explore the effects of various shaped (spheres, rods) and charged (negative, positive) gold ENMs on Daphnia magna (D. magna) in terms of survival, ENM uptake and production of reactive oxygen species (ROS), a key factor in oxidative stress responses. We also investigate the effects of gold ENMs binding to the carapace of D. magna and how this may induce moulting inhibition in addition to toxicity and stress. The findings suggest that ENM shape and surface charge play an important role in determining ENM uptake and toxicity. Full article
►▼ Show Figures

Figure 1

Figure 1
<p>Survival curves of <span class="html-italic">Daphnia magna</span> (<span class="html-italic">D. magna</span>) neonates exposed to (<b>a</b>) positively charged mass concentration; (<b>b</b>) negatively charged mass concentration; (<b>c</b>) positively charged number concentration; and (<b>d</b>) negatively charged number concentration of spherical, short rod, and long rod shaped gold engineered nanomaterials (ENMs). Note: Even at the highest concentration of 50 µg/mL, negatively charged ENMs did not acquire a half maximal effective concentration (EC<sub>50</sub>). Higher number concentrations for negatively charged ENMs can be seen in <a href="#app1-nanomaterials-06-00222" class="html-app">Figure S2</a>.</p> Full article ">Figure 2
<p>Titration of 0.01 mM KCl to positively charged spherical and short rod gold ENMs and subsequent change in zeta-potential.</p> Full article ">Figure 3
<p>Fluorescent confocal image of <span class="html-italic">D. magna</span> neonate retaining NH<sub>2</sub>-gold ENMs conjugated with Rhodamine B Isothiocyanate (RhB-ITC) (<b>a</b>) and control (<b>b</b>).</p> Full article ">Figure 4
<p>Reactive oxygen species generation and recovery (0–24 h) in response to high and low number concentration exposures of negatively charged spheres (<b>a</b>); positively charged spheres (<b>b</b>); and positively charged short rods (<b>c</b>).</p> Full article ">Figure 5
<p>Moulting success of <span class="html-italic">D. magna</span> neonates (6 h) exposed to 5.3 × 10<sup>6</sup> ENMs/mL of spherical and short rod gold ENMs for 84 h. Numbers on top of bars indicate daphnia mortality.</p> Full article ">
Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:
 
Displaying articles 1-23
Previous Issue
Next Issue
Back to TopTop