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Nanomaterials
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Nanomaterials, Volume 6, Issue 6 (June 2016) – 25 articles

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4100 KiB  
Article
Hydrothermal Fabrication of Silver Nanowires-Silver Nanoparticles-Graphene Nanosheets Composites in Enhancing Electrical Conductive Performance of Electrically Conductive Adhesives
by Hongru Ma, Jinfeng Zeng, Steven Harrington, Lei Ma, Mingze Ma, Xuhong Guo and Yanqing Ma
Nanomaterials 2016, 6(6), 119; https://doi.org/10.3390/nano6060119 - 21 Jun 2016
Cited by 36 | Viewed by 7512
Abstract
Silver nanowires-silver nanoparticles-graphene nanosheets (AgNWs-AgNPs-GN) hybrid nanomaterials were fabricated through a hydrothermal method by using glucose as a green reducing agent. The charge carriers of AgNWs-AgNPs-GN passed through defect regions in the GNs rapidly with the aid of the AgNW and AgNP building [...] Read more.
Silver nanowires-silver nanoparticles-graphene nanosheets (AgNWs-AgNPs-GN) hybrid nanomaterials were fabricated through a hydrothermal method by using glucose as a green reducing agent. The charge carriers of AgNWs-AgNPs-GN passed through defect regions in the GNs rapidly with the aid of the AgNW and AgNP building blocks, leading to high electrical conductivity of electrically conductive adhesives (ECA) filled with AgNWs-AgNPs-GN. The morphologies of synthesized AgNWs-AgNPs-GN hybrid nanomaterials were characterized by field emission scanning electron microscope (FESEM), and high resolution transmission electron microscopy (HRTEM). X-ray diffraction (XRD) and laser confocal micro-Raman spectroscopy were used to investigate the structure of AgNWs-AgNPs-GN. The resistance of cured ECAs was investigated by the four-probe method. The results indicated AgNWs-AgNPs-GN hybrid nanomaterials exhibited excellent electrical properties for decreasing the resistivity of electrically conductive adhesives (ECA). The resistivity of ECA was 3.01 × 10−4 Ω·cm when the content of the AgNWs-AgNPs-GN hybrid nanomaterial was 0.8 wt %. Full article
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Schematic of preparing the silver nanowires-silver nanoparticles-graphene nanosheets (AgNWs-AgNPs-GN).</p> Full article ">Figure 2
<p>Field emission scanning electron microscopy (FE-SEM) images of the AgNWs (<b>A</b>) and AgNWs-AgNPs-GN (<b>B</b>).</p> Full article ">Figure 3
<p>High resolution transmission electron microscopy (HRTEM) images of the AgNWs-AgNPs-GN (<b>A</b>) and magnification of one segment of the AgNWs-AgNPs-GN (<b>B</b>).</p> Full article ">Figure 4
<p>X-ray powder diffractometer (XRD) patterns of graphene oxide (GO) and AgNWs-AgNPs-GN (a: AgNWs-GNs, b: GO).</p> Full article ">Figure 5
<p>Raman spectra of GO, GN and AgNWs-AgNPs-GN (a: AgNWs-GNs, b: GO, c: GN).</p> Full article ">Figure 6
<p>X-ray photoelectron spectroscopy (XPS) wide-scans of AgNWs-AgNPs-GN (a) and GO (b), insert: magnification of segment of a line (<b>A</b>) and C 1s narrow-scans XPS spectra of AgNWs-AgNPs-GN (<b>B</b>).</p> Full article ">Figure 7
<p>Resistivity of electrically conductive adhesives (ECA)-changing trend image under different contents of AgNWs-AgNPs-GN.</p> Full article ">Figure 8
<p>SEM images of cross-section morphology of electrically conductive adhesives (ECA) filled with 0.0 wt % AgNWs-AgNPs-GN (<b>A</b>), 0.2 wt % AgNWs-AgNPs-GN (<b>B</b>), 0.5 wt % AgNWs-AgNPs-GN (<b>C</b>), 0.8 wt % AgNWs-AgNPs-GN (<b>D</b>), and 1.1 wt % AgNWs-AgNPs-GN (<b>E</b>).</p> Full article ">
5271 KiB  
Article
Quaternized Carboxymethyl Chitosan-Based Silver Nanoparticles Hybrid: Microwave-Assisted Synthesis, Characterization and Antibacterial Activity
by Siqi Huang, Jing Wang, Yang Zhang, Zhiming Yu and Chusheng Qi
Nanomaterials 2016, 6(6), 118; https://doi.org/10.3390/nano6060118 - 17 Jun 2016
Cited by 25 | Viewed by 8562
Abstract
A facile, efficient, and eco-friendly approach for the preparation of uniform silver nanoparticles (Ag NPs) was developed. The synthesis was conducted in an aqueous medium exposed to microwave irradiation for 8 min, using laboratory-prepared, water-soluble quaternized carboxymethyl chitosan (QCMC) as a chemical reducer [...] Read more.
A facile, efficient, and eco-friendly approach for the preparation of uniform silver nanoparticles (Ag NPs) was developed. The synthesis was conducted in an aqueous medium exposed to microwave irradiation for 8 min, using laboratory-prepared, water-soluble quaternized carboxymethyl chitosan (QCMC) as a chemical reducer and stabilizer and silver nitrate as the silver source. The structure of the prepared QCMC was characterized using Fourier transform infrared (FT-IR) and 1H nuclear magnetic resonance (NMR). The formation, size distribution, and dispersion of the Ag NPs in the QCMC matrix were determined using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible (UV-Vis), transmission electron microscopy (TEM), and field emission scanning electron microscope (FESEM) analysis, and the thermal stability and antibacterial properties of the synthesized QCMC-based Ag NPs composite (QCMC-Ag) were also explored. The results revealed that (1) QCMC was successfully prepared by grafting quaternary ammonium groups onto carboxymethyl chitosan (CMC) chains under microwave irradiation in water for 90 min and this substitution appeared to have occurred at -NH2 sites on C2 position of the pyranoid ring; (2) uniform and stable spherical Ag NPs could be synthesized when QCMC was used as the reducing and stabilizing agent; (3) Ag NPs were well dispersed in the QCMC matrix with a narrow size distribiution in the range of 17–31 nm without aggregation; and (4) due to the presence of Ag NPs, the thermal stability and antibacterial activity of QCMC-Ag were dramatically improved relative to QCMC. Full article
(This article belongs to the Special Issue Polysaccharide-Based Nanosorbent Materials: Fundamental Science and Beyond)
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Figure 1

Figure 1
<p>Chemical structure of (<b>a</b>) carboxymethyl chitosan (CMC) and (<b>b</b>) 2,3-epoxypropyltrimethyl ammonium chloride (ETA).</p> Full article ">Figure 2
<p>Fourier transform infrared (FT-IR) spectra of (<b>a</b>) carboxymethyl chitosan (CMC) and (<b>b</b>) Quaternized carboxymethyl chitosan (QCMC).</p> Full article ">Figure 3
<p><sup>1</sup>H nuclear magnetic resonance (NMR) spectrum of QCMC.</p> Full article ">Figure 4
<p>The reaction illustration of QCMC.</p> Full article ">Figure 5
<p>X-ray diffraction (XRD) patterns of (<b>a</b>) CMC, (<b>b</b>) QCMC and (<b>c</b>) QCMC-Ag.</p> Full article ">Figure 6
<p>X-ray photoelectron spectroscopy (XPS) spectra of as-prepared QCMC-Ag. (<b>I</b>): Survey-scan spectrum. (<b>II</b>): High-resolution Ag 3d spectrum.</p> Full article ">Figure 7
<p>Ultraviolet-visible (UV-Vis) spectra of (<b>a</b>) QCMC and (<b>b</b>) QCMC-Ag.</p> Full article ">Figure 8
<p>(<b>a</b>) Transmission electron microscopy (TEM) image of QCMC-Ag; (<b>b</b>) size distribution histogram of Ag NPs; (<b>c</b>) inverse fast Fourier transform (IFFT) image and (<b>d</b>) selected area electron diffraction (SAED) pattern.</p> Full article ">Figure 8 Cont.
<p>(<b>a</b>) Transmission electron microscopy (TEM) image of QCMC-Ag; (<b>b</b>) size distribution histogram of Ag NPs; (<b>c</b>) inverse fast Fourier transform (IFFT) image and (<b>d</b>) selected area electron diffraction (SAED) pattern.</p> Full article ">Figure 9
<p>Field emission scanning electron microscope (FESEM) micrographs of (<b>a</b>,<b>c</b>) QCMC and (<b>b</b>,<b>d</b>) QCMC-Ag.</p> Full article ">Figure 10
<p>Thermogravimetric (TG) curves of (<b>a</b>) CMC, (<b>b</b>) QCMC and (<b>c</b>) QCMC-Ag, (<b>I</b>): thermogravimetric analysis (TGA) curves; (<b>II</b>): derivative thermogravimetry (DTG) curves.</p> Full article ">Figure 11
<p>Appearance of colonies of Staphylococcus aureus after treatment with CMC, QCMC , Ag NPs and QCMC-Ag at a concentration of 0.005%: (<b>a</b>) blank; (<b>b</b>) CMC; (<b>c</b>) QCMC; (<b>d</b>) Ag NPs and (<b>e</b>) QCMC-Ag.</p> Full article ">
2202 KiB  
Communication
Ag Nanoparticle–Functionalized Open-Ended Freestanding TiO2 Nanotube Arrays with a Scattering Layer for Improved Energy Conversion Efficiency in Dye-Sensitized Solar Cells
by Won-Yeop Rho, Myeung-Hwan Chun, Ho-Sub Kim, Hyung-Mo Kim, Jung Sang Suh and Bong-Hyun Jun
Nanomaterials 2016, 6(6), 117; https://doi.org/10.3390/nano6060117 - 15 Jun 2016
Cited by 25 | Viewed by 7014
Abstract
Dye-sensitized solar cells (DSSCs) were fabricated using open-ended freestanding TiO2 nanotube arrays functionalized with Ag nanoparticles (NPs) in the channel to create a plasmonic effect, and then coated with large TiO2 NPs to create a scattering effect in order to improve [...] Read more.
Dye-sensitized solar cells (DSSCs) were fabricated using open-ended freestanding TiO2 nanotube arrays functionalized with Ag nanoparticles (NPs) in the channel to create a plasmonic effect, and then coated with large TiO2 NPs to create a scattering effect in order to improve energy conversion efficiency. Compared to closed-ended freestanding TiO2 nanotube array–based DSSCs without Ag or large TiO2 NPs, the energy conversion efficiency of closed-ended DSSCs improved by 9.21% (actual efficiency, from 5.86% to 6.40%) with Ag NPs, 6.48% (actual efficiency, from 5.86% to 6.24%) with TiO2 NPs, and 14.50% (actual efficiency, from 5.86% to 6.71%) with both Ag NPs and TiO2 NPs. By introducing Ag NPs and/or large TiO2 NPs to open-ended freestanding TiO2 nanotube array–based DSSCs, the energy conversion efficiency was improved by 9.15% (actual efficiency, from 6.12% to 6.68%) with Ag NPs and 8.17% (actual efficiency, from 6.12% to 6.62%) with TiO2 NPs, and by 15.20% (actual efficiency, from 6.12% to 7.05%) with both Ag NPs and TiO2 NPs. Moreover, compared to closed-ended freestanding TiO2 nanotube arrays, the energy conversion efficiency of open-ended freestanding TiO2 nanotube arrays increased from 6.71% to 7.05%. We demonstrate that each component—Ag NPs, TiO2 NPs, and open-ended freestanding TiO2 nanotube arrays—enhanced the energy conversion efficiency, and the use of a combination of all components in DSSCs resulted in the highest energy conversion efficiency. Full article
(This article belongs to the Special Issue Nanostructured Solar Cells)
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Figure 1

Figure 1
<p>Overall scheme of dye-sensitized solar cells (DSSCs) with open-ended freestanding TiO<sub>2</sub> nanotube arrays with Ag nanoparticles (NPs) and large TiO<sub>2</sub> NPs. (<b>A</b>) (a) Ti anodization for TiO<sub>2</sub> nanotube arrays; (b) freestanding TiO<sub>2</sub> nanotube arrays and etching by ion milling; (c) transference of open-ended freestanding TiO<sub>2</sub> nanotube arrays onto fluorine-doped tin oxide (FTO) glass; (d) formation of Ag NPs by ultraviolet (UV) irradiation; and (e) introduction of large TiO<sub>2</sub> NPs. (<b>B</b>) Structure of a DSSC with freestanding TiO<sub>2</sub> nanotube arrays and large TiO<sub>2</sub> NPs.</p> Full article ">Figure 2
<p>Field emission scanning electron microscope (FE-SEM) images of the (<b>a</b>) top, (<b>b</b>) bottom, and (<b>c</b>) bottom of post–ion milling freestanding TiO<sub>2</sub> nanotube arrays; (<b>d</b>) a high-angle annular dark-field (HAADF) image of Ag NPs in the channel of TiO<sub>2</sub> nanotube arrays; and (<b>e</b>) a side view of the active layer with freestanding TiO<sub>2</sub> nanotube arrays and a scattering layer.</p> Full article ">Figure 3
<p>Ultraviolet-visible (UV-vis) spectrum of Ag NP-functionalized TiO<sub>2</sub> nanotubes.</p> Full article ">Figure 4
<p>I–V curves of DSSC-based closed-ended freestanding TiO<sub>2</sub> nanotube arrays fabricated without NPs (<b>a</b>), with Ag NPs (<b>b</b>), with large TiO<sub>2</sub> NPs (<b>c</b>), and with Ag NPs and large TiO<sub>2</sub> NPs (<b>d</b>).</p> Full article ">Figure 5
<p>I–V curves of DSSCs based on open-ended freestanding TiO<sub>2</sub> nanotube arrays fabricated without NPs (<b>a</b>), with Ag NPs (<b>b</b>), with large TiO<sub>2</sub> NPs (<b>c</b>), and with both Ag NPs and large TiO<sub>2</sub> NPs (<b>d</b>).</p> Full article ">
3898 KiB  
Article
Human Serum Albumin Nanoparticles for Use in Cancer Drug Delivery: Process Optimization and In Vitro Characterization
by Nikita Lomis, Susan Westfall, Leila Farahdel, Meenakshi Malhotra, Dominique Shum-Tim and Satya Prakash
Nanomaterials 2016, 6(6), 116; https://doi.org/10.3390/nano6060116 - 15 Jun 2016
Cited by 125 | Viewed by 11656
Abstract
Human serum albumin nanoparticles (HSA-NPs) are widely-used drug delivery systems with applications in various diseases, like cancer. For intravenous administration of HSA-NPs, the particle size, surface charge, drug loading and in vitro release kinetics are important parameters for consideration. This study focuses on [...] Read more.
Human serum albumin nanoparticles (HSA-NPs) are widely-used drug delivery systems with applications in various diseases, like cancer. For intravenous administration of HSA-NPs, the particle size, surface charge, drug loading and in vitro release kinetics are important parameters for consideration. This study focuses on the development of stable HSA-NPs containing the anti-cancer drug paclitaxel (PTX) via the emulsion-solvent evaporation method using a high-pressure homogenizer. The key parameters for the preparation of PTX-HSA-NPs are: the starting concentrations of HSA, PTX and the organic solvent, including the homogenization pressure and its number cycles, were optimized. Results indicate a size of 143.4 ± 0.7 nm and 170.2 ± 1.4 nm with a surface charge of −5.6 ± 0.8 mV and −17.4 ± 0.5 mV for HSA-NPs and PTX-HSA-NPs (0.5 mg/mL of PTX), respectively. The yield of the PTX-HSA-NPs was ~93% with an encapsulation efficiency of ~82%. To investigate the safety and effectiveness of the PTX-HSA-NPs, an in vitro drug release and cytotoxicity assay was performed on human breast cancer cell line (MCF-7). The PTX-HSA-NPs showed dose-dependent toxicity on cells of 52%, 39.3% and 22.6% with increasing concentrations of PTX at 8, 20.2 and 31.4 μg/mL, respectively. In summary, all parameters involved in HSA-NPs’ preparation, its anticancer efficacy and scale-up are outlined in this research article. Full article
(This article belongs to the Special Issue Nanomaterials for Cancer Therapies)
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Figure 1

Figure 1
<p>Effect of homogenization pressure (psi) on the (<b>a</b>) human serum albumin-nanoparticle (HAS-NP) size (mean ± SD, <span class="html-italic">n</span> = 10), represented as columns, and polydispersity index, represented as line; (<b>b</b>) zeta potential of HSA-NPs (mean ± SD, <span class="html-italic">n</span> = 10), represented as columns, prepared from 20 mg/mL starting HSA concentration, 12 homogenization cycles and a chloroform concentration of 3% <span class="html-italic">v</span>/<span class="html-italic">v</span> of starting HSA solution (*** <span class="html-italic">p</span> &lt; 0.0001; ns = not significant).</p> Full article ">Figure 2
<p>Effect of varying the number of homogenization cycles on the (<b>a</b>) HSA-NP size (mean ± SD), <span class="html-italic">n =</span> 10), represented as columns, and polydispersity index, represented as line; (<b>b</b>) zeta potential of HSA-NPs (mean ± SD, <span class="html-italic">n =</span> 10), represented as columns, prepared from a 20 mg/mL starting HSA concentration, 20,000 psi pressure with a chloroform concentration of 3% <span class="html-italic">v</span>/<span class="html-italic">v</span> of starting HSA solution (*** <span class="html-italic">p</span> &lt; 0.0001; ns = not significant).</p> Full article ">Figure 3
<p>Effect of the starting HSA concentration (mg/mL) on the (<b>a</b>) HSA-NP size (mean ± SD, <span class="html-italic">n</span> = 10), represented as columns, and polydispersity index, represented as line; (<b>b</b>) zeta potential of HSA-NPs (mean ± SD, <span class="html-italic">n</span> = 10), represented as columns, prepared with a chloroform concentration of 3% <span class="html-italic">v</span>/<span class="html-italic">v</span> of starting HSA solution, 12 homogenization cycles and 20,000 psi homogenization pressure (*** <span class="html-italic">p</span> &lt; 0.0001; ns = not significant).</p> Full article ">Figure 4
<p>Effect of chloroform concentration (% <span class="html-italic">v</span>/<span class="html-italic">v</span> of starting HSA solution) on the (<b>a</b>) HSA-NP size (mean ± SD, <span class="html-italic">n</span> = 10), represented as columns, and polydispersity index, represented as line; (<b>b</b>) zeta potential of HSA-NPs (mean ± SD, <span class="html-italic">n</span> = 10), represented as columns, prepared from a 10 mg/mL HSA concentration, 20,000 psi homogenization pressure and 12 homogenization cycles (*** <span class="html-italic">p</span> &lt; 0.0001; ns = not significant).</p> Full article ">Figure 5
<p>Effect of chloroform-ethanol concentration (% <span class="html-italic">v/v</span> of starting HSA solution) on the (<b>a</b>) HSA-NP size (mean ± SD, <span class="html-italic">n</span> = 10), represented as columns, and polydispersity index , represented as line; (<b>b</b>) zeta potential of HSA-NPs (mean ± SD, <span class="html-italic">n</span> = 10), represented as columns, prepared from a 10 mg/mL HSA concentration, 20,000 psi homogenization pressure and 12 homogenization cycles (*** <span class="html-italic">p</span> &lt; 0.0001; ns = not significant).</p> Full article ">Figure 6
<p>Effect of paclitaxel (PTX) concentration (mg/mL) on the (<b>a</b>) HSA-NP size (mean ± SD, <span class="html-italic">n</span> = 10), represented as columns, and polydispersity index, represented as line; (<b>b</b>) zeta potential of HSA-NPs (mean ± SD, <span class="html-italic">n</span> = 10), represented as columns, prepared from a 10 mg/mL starting HSA concentration, a 3% <span class="html-italic">v</span>/<span class="html-italic">v</span> CHCl<sub>3</sub>-EtOH concentration, 20,000 psi homogenization pressure and 12 cycles of homogenization (*** <span class="html-italic">p</span> &lt; 0.0001).</p> Full article ">Figure 7
<p>(<b>a</b>) Scanning electron microscope (SEM) image of HSA-NPs of a size of 143.4 ± 0.7 nm and a charge of −5.6 ± 0.8 mV, prepared from optimized experimental conditions (scale = 500 nm). (<b>b</b>) SEM image of paclitaxel human serum albumin nanoparticles (PTX-HSA-NPs) of a size of 177.1 ± 2.5 nm and a charge of −26.8 ± 3.1 mV, prepared from optimized experimental conditions with a 1 mg/mL starting paclitaxel (PTX) concentration (scale = 500 nm).</p> Full article ">Figure 8
<p>Cumulative drug release (mean ± SD %, <span class="html-italic">n</span> = 3) profiles of PTX-HSA-NPs prepared from different PTX starting concentrations (0.5, 1 and 1.5 mg/mL) compared to HSA-NPs (without PTX) displaying the cumulative release of PTX from PTX-HSA-NPs over time intervals of 0, 1, 2, 9, 12, 18, 24 and 48 h.</p> Full article ">Figure 9
<p>Dye 3-(4,5-dimtheylthiazol-2-yl)-2,5-diphenltetrazoliumbromide (MTT) assay measuring the effect of PTX-HSA-NPs, prepared from different starting PTX concentrations, on the cell viability of human breast cancer cell line (MCF-7) as compared to HSA-NPs at 24 and 48 h, respectively. The graph shows a representative result of (<span class="html-italic">n</span> = 3) mean ± S.D. * <span class="html-italic">p</span> &lt; 0.05, ** <span class="html-italic">p</span> &lt; 0.01 and *** <span class="html-italic">p</span> &lt; 0.001 were considered significant based on Tuckey’s <span class="html-italic">post hoc</span> analysis.</p> Full article ">Figure 10
<p>Cell viability for PTX-HSA-NPs and free PTX in MCF-7 breast cancer cells with the mean ± 95% confidence interval. The graph was fitted using a nonlinear regression model in GraphPad Prism software version 5.01 (GraphPad Software Inc., La Jolla, CA, USA) and IC<sub>50</sub> was calculated using the dose-response inhibitory equation.</p> Full article ">
3935 KiB  
Article
Correlation between CdSe QD Synthesis, Post-Synthetic Treatment, and BHJ Hybrid Solar Cell Performance
by Michael Eck and Michael Krueger
Nanomaterials 2016, 6(6), 115; https://doi.org/10.3390/nano6060115 - 14 Jun 2016
Cited by 8 | Viewed by 4756
Abstract
In this publication we show that the procedure to synthesize nanocrystals and the post-synthetic nanocrystal ligand sphere treatment have a great influence not only on the immediate performance of hybrid bulk heterojunction solar cells, but also on their thermal, long-term, and air stability. [...] Read more.
In this publication we show that the procedure to synthesize nanocrystals and the post-synthetic nanocrystal ligand sphere treatment have a great influence not only on the immediate performance of hybrid bulk heterojunction solar cells, but also on their thermal, long-term, and air stability. We herein demonstrate this for the particular case of spherical CdSe nanocrystals, post-synthetically treated with a hexanoic acid based treatment. We observe an influence from the duration of this post-synthetic treatment on the nanocrystal ligand sphere size, and also on the solar cell performance. By tuning the post-synthetic treatment to a certain degree, optimal device performance can be achieved. Moreover, we show how to effectively adapt the post-synthetic nanocrystal treatment protocol to different nanocrystal synthesis batches, hence increasing the reproducibility of hybrid nanocrystal:polymer bulk-heterojunction solar cells, which usually suffers due to the fluctuations in nanocrystal quality of different synthesis batches and synthesis procedures. Full article
(This article belongs to the Special Issue Nanostructured Solar Cells)
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Figure 1

Figure 1
<p>(<b>a</b>) Working principle and device structure shown on the cross-sectional and on the top view of the investigated hybrid bulk heterojunction (BHJ) solar cell with the active area size of 0.07 cm<sup>2</sup>. (<b>b</b>) Power conversion efficiencies of selected hybrid BHJ solar cells published over the years from nanocrystals (NCs) of different shape: quantum dots (QD) [<a href="#B2-nanomaterials-06-00115" class="html-bibr">2</a>,<a href="#B3-nanomaterials-06-00115" class="html-bibr">3</a>,<a href="#B6-nanomaterials-06-00115" class="html-bibr">6</a>,<a href="#B7-nanomaterials-06-00115" class="html-bibr">7</a>,<a href="#B8-nanomaterials-06-00115" class="html-bibr">8</a>,<a href="#B9-nanomaterials-06-00115" class="html-bibr">9</a>,<a href="#B10-nanomaterials-06-00115" class="html-bibr">10</a>,<a href="#B11-nanomaterials-06-00115" class="html-bibr">11</a>,<a href="#B12-nanomaterials-06-00115" class="html-bibr">12</a>], nanorods (NR) [<a href="#B5-nanomaterials-06-00115" class="html-bibr">5</a>,<a href="#B10-nanomaterials-06-00115" class="html-bibr">10</a>,<a href="#B13-nanomaterials-06-00115" class="html-bibr">13</a>,<a href="#B14-nanomaterials-06-00115" class="html-bibr">14</a>,<a href="#B15-nanomaterials-06-00115" class="html-bibr">15</a>], multipods (MP) [<a href="#B4-nanomaterials-06-00115" class="html-bibr">4</a>,<a href="#B10-nanomaterials-06-00115" class="html-bibr">10</a>,<a href="#B16-nanomaterials-06-00115" class="html-bibr">16</a>,<a href="#B17-nanomaterials-06-00115" class="html-bibr">17</a>,<a href="#B18-nanomaterials-06-00115" class="html-bibr">18</a>,<a href="#B19-nanomaterials-06-00115" class="html-bibr">19</a>,<a href="#B20-nanomaterials-06-00115" class="html-bibr">20</a>].</p> Full article ">Figure 2
<p>(<b>a</b>) Transmission electron microscopy (TEM) image of CdSe nanocrystals (NCs) used for the investigation from a 100:3:2 (hexadecylamine/trioctylphosphine oxide):(cadmium-stearic acid):(trioctylphosphine-selenid) ((HDA/TOPO):(Cd-SA):(TOP-Se)) ratio, synthesized for 30 min at 300 °C by wet-chemical hot injection NC synthesis with an average diameter of 6.5 nm. (<b>b</b>) Ultraviolet-visible (UV-Vis) absorption spectrum (blue line) and photoluminescence spectrum of CdSe nanocrystals (NCs) synthesized by a hot injection method recorded at an excitation of 575 nm (red line).</p> Full article ">Figure 3
<p>Different Cd:Se precursor ratios and concentrations—full width at half maximum (FWHM), photoluminescence (PL) peak position, and PL intensity evolution during the NC syntheses.</p> Full article ">Figure 4
<p>Red squares: Development of PL intensity over the HA washing time for CdSe QDs synthesized in hexadecylamine/trioctylphosphine oxide (HDA/TOPO) (100:3:2, 30 min at 300 °C). Blue dots: Respective development of the hydrodynamic diameter together with the standard deviation for CdSe QDs measured by dynamic light scattering (DLS). For both, the half-life τ in min is given for the respective fitted exponential decay.</p> Full article ">Figure 5
<p>Dependency of open-circuit voltage (<span class="html-italic">V</span><sub>OC</sub>), fill factor (FF), short-circuit current density (<span class="html-italic">J</span><sub>SC</sub>) and PCE on the HA washing time at 105 °C for hybrid BHJ solar cells containing CdSe NCs taken from the respective PL brightpoint of the NC hot-injection syntheses performed at 300 °C with a 100:3:2, 100:2:2, and 100:2:3 ratio of (HDA/TOPO):(Cd-SA):(TOP-Se). The results are obtained from two synthesis batches for each ratio and from 60 solar cells, which were thermally post-annealed until reaching their optimal performance.</p> Full article ">Figure 6
<p>Power conversion efficiencies (PCEs) (red spherical points) obtained from 36 hybrid BHJ solar cells containing CdSe QDs (100:2:2) washed for different times in HA, and the optimal annealing time (black rhombic points) required to reach this efficiency.</p> Full article ">Figure 7
<p>Differently long HA washed CdSe QDs (100:2:2) exhibit different performances when incorporated inside hybrid BHJ solar cells both without annealing and with 10 min of thermal annealing at 145 °C (results obtained from 36 cells).</p> Full article ">Figure 8
<p>Incorporating differently long HA washed CdSe QDs (100:2:2) into BHJ hybrid solar cells results in different series resistance (<span class="html-italic">R<sub>S</sub></span>) and parallel resistance (<span class="html-italic">R<sub>P</sub></span>) values before and after 10 min of thermal annealing.</p> Full article ">Figure 9
<p>Parameters of PCPDTBT:CdSe QD solar cells from QDs washed by HA for 10 min (turquoise &amp; blue squares), 12 min (green spherical points), and 21 min (orange &amp; red rhombic points), stored in the dark inside a glovebox and periodically illuminated by a sun-simulator (AM 1.5 G spectrum) and characterized inside the same glovebox.</p> Full article ">Figure 10
<p>Development by time of short circuit current densities, series resistances, open circuit voltages, and parallel resistances for hybrid BHJ CdSe/PCPDTBT solar cells with short-time HA washed and long-time HA washed NCs, and for an organic BHJ PC<sub>61</sub>BM/PCPDTBT solar cell for comparison when taken into air. Since the J<sub>SC</sub> of the solar cell containing short washed QDs displayed a fast initial decrease from its original value, an extrapolated graph has been added to guide the eye.</p> Full article ">
146 KiB  
Erratum
Erratum: Mustafa, R.; Luo, Y.; Wu, Y.; Guo, R.; Shi, X. Dendrimer-Functionalized Laponite® Nanodisks as a Platform for Anticancer Drug Delivery. Nanomaterials 2015, 5, 1716–1731
by Nanomaterials Editorial Office
Nanomaterials 2016, 6(6), 114; https://doi.org/10.3390/nano6060114 - 14 Jun 2016
Viewed by 2904
Abstract
It has been brought to our attention that Laponite® is a trademark of BYK Additives, however the trademark symbol is missing in [1].[...] Full article
1578 KiB  
Article
Targeting and Photodynamic Killing of Cancer Cell by Nitrogen-Doped Titanium Dioxide Coupled with Folic Acid
by Jin Xie, Xiaobo Pan, Mengyan Wang, Longfang Yao, Xinyue Liang, Jiong Ma, Yiyan Fei, Pei-Nan Wang and Lan Mi
Nanomaterials 2016, 6(6), 113; https://doi.org/10.3390/nano6060113 - 14 Jun 2016
Cited by 26 | Viewed by 6158
Abstract
Titanium dioxide (TiO2) has attracted wide attention as a potential photosensitizer (PS) in photodynamic therapy (PDT). However, bare TiO2 can only be excited by ultraviolet illumination, and it lacks specific targeting ligands, which largely impede its application. In our study, [...] Read more.
Titanium dioxide (TiO2) has attracted wide attention as a potential photosensitizer (PS) in photodynamic therapy (PDT). However, bare TiO2 can only be excited by ultraviolet illumination, and it lacks specific targeting ligands, which largely impede its application. In our study, we produced nitrogen-doped TiO2 and linked it with an effective cancer cell targeting agent, folic acid (FA), to obtain N-TiO2-FA nanoconjugates. Characterization of N-TiO2-FA included Zeta potential, absorption spectra and thermogravimetric analysis. The results showed that N-TiO2-FA was successfully produced and it possessed better dispersibility in aqueous solution than unmodified TiO2. The N-TiO2-FA was incubated with human nasopharyngeal carcinoma (KB) and human pulmonary adenocarcinoma (A549) cells. The KB cells that overexpress folate receptors (FR) on cell membranes were used as FR-positive cancer cells, while A549 cells were used as FR-negative cells. Laser scanning confocal microscopy results showed that KB cells had a higher uptake efficiency of N-TiO2-FA, which was about twice that of A549 cells. Finally, N-TiO2-FA is of no cytotoxicity, and has a better photokilling effect on KB cells under visible light irradiation. In conclusion, N-TiO2-FA can be as high-value as a PS in cancer targeting PDT. Full article
(This article belongs to the Special Issue Nanomaterials for Cancer Therapies)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Synthesis procedure of N-TiO<sub>2</sub>-folic acid (FA) nanoparticles (NPs).</p> Full article ">Figure 2
<p>(<b>A</b>) Comparison of the absorption spectrum of 1 μg·mL<sup>−1</sup> folic acid (FA) solution and the subtraction spectrum of N-TiO<sub>2</sub>-FA subtracting N-TiO<sub>2</sub>-NH<sub>2</sub>; (<b>B</b>) Absorption spectra of N-TiO<sub>2</sub> and N-TiO<sub>2</sub>-FA NPs; (<b>C</b>) Thermogravimetric analysis of the air-dried N-TiO<sub>2</sub>, N-TiO<sub>2</sub>-NH<sub>2</sub> and N-TiO<sub>2</sub>-FA NPs.</p> Full article ">Figure 3
<p>(<b>A</b>) Confocal microscopic images of human nasopharyngeal carcinoma (KB) and human pulmonary adenocarcinoma (A549) cells treated with N-TiO<sub>2</sub>-FA (red) for 40 min. Scale bar is 50 μm. (<b>B</b>) Reflection intensity of internalized N-TiO<sub>2</sub>-FA in KB (black), FA-pretreated KB (red), A549 (blue) cells and FA-pretreated A549 (green) as a function of incubation time.</p> Full article ">Figure 4
<p>The dark cytotoxicity of N-TiO<sub>2</sub>-FA with the incubation concentrations of 50–200 μg·mL<sup>−1</sup> on KB and A549 cells. The control groups of untreated cells were also shown for comparison. Data are expressed as mean ± SD (<span class="html-italic">n</span> = 4).</p> Full article ">Figure 5
<p>Photokilling effects of N-TiO<sub>2</sub>-FA (green) and N-TiO<sub>2</sub>-NH<sub>2</sub> (blue) with the concentration of 200 μg·mL<sup>−1</sup> on A549 and KB cells. The control group (black) and light irradiated group (red) were also shown for comparison. Data are expressed as mean ± SD (<span class="html-italic">n</span> = 4).</p> Full article ">
4611 KiB  
Article
Gd-Si Oxide Nanoparticles as Contrast Agents in Magnetic Resonance Imaging
by Alejandro Cabrera-García, Alejandro Vidal-Moya, Ángela Bernabeu, Jesús Pacheco-Torres, Elisa Checa-Chavarria, Eduardo Fernández and Pablo Botella
Nanomaterials 2016, 6(6), 109; https://doi.org/10.3390/nano6060109 - 8 Jun 2016
Cited by 14 | Viewed by 5849
Abstract
We describe the synthesis, characterization and application as contrast agents in magnetic resonance imaging of a novel type of magnetic nanoparticle based on Gd-Si oxide, which presents high Gd3+ atom density. For this purpose, we have used a Prussian Blue analogue as [...] Read more.
We describe the synthesis, characterization and application as contrast agents in magnetic resonance imaging of a novel type of magnetic nanoparticle based on Gd-Si oxide, which presents high Gd3+ atom density. For this purpose, we have used a Prussian Blue analogue as the sacrificial template by reacting with soluble silicate, obtaining particles with nanorod morphology and of small size (75 nm). These nanoparticles present good biocompatibility and higher longitudinal and transversal relaxivity values than commercial Gd3+ solutions, which significantly improves the sensitivity of in vivo magnetic resonance images. Full article
(This article belongs to the Special Issue Nanomaterials for Cancer Therapies)
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<p>Powder X-ray diffraction (XRD) pattern of as-made GdFe nanorods.</p> Full article ">Figure 2
<p>Electron microscopy study of as synthesized GdFe nanorods. (<b>a</b>,<b>b</b>): Transmission electron microscopy (TEM) (<b>a</b>) and field-emission scanning electronic microscopy (FESEM) (<b>b</b>) images; (<b>c</b>) Scanning transmission electron microscopy (STEM) image with energy-dispersive X-ray spectroscopy analysis (EDS) line scans. Legend: blue line = Gd; red line = Fe; (<b>d</b>,<b>f</b>): STEM image (<b>d</b>) and EDS mapping pictures of one GdFe nanorod (<b>e</b>,<b>f</b>).</p> Full article ">Figure 3
<p>Electron microscopy study of GdSi nanorods obtained by alkaline transformation of GdFe precursor. (<b>a</b>,<b>b</b>): TEM (<b>a</b>) and FESEM (<b>b</b>) images of GdSi nanoparticles; (<b>c</b>) EDS elemental analysis; (<b>d</b>) STEM image with EDS line scans. Legend: blue line = Gd; red line = Fe; green line = Si; (<b>e</b>–<b>h</b>) STEM image (<b>e</b>) and EDS mapping pictures of two GdSi nanorods (<b>f</b>–<b>h</b>).</p> Full article ">Figure 4
<p>Particle hydrodynamic diameter of GdSi sample as determined in water by DLS.</p> Full article ">Figure 5
<p><span class="html-italic">T</span><sub>1</sub> (<b>a</b>) and <span class="html-italic">T</span><sub>2</sub> (<b>b</b>) relaxation rate measurements <span class="html-italic">vs</span> concentration of GdSi aqueous solutions (0.1% xanthan gum) at a magnetic field of 3 T. Legend: (<math display="inline"> <semantics> <mrow> <mstyle mathcolor="#C00000"> <mo>□</mo> </mstyle> </mrow> </semantics> </math>) GdSi; (<math display="inline"> <semantics> <mrow> <mstyle mathcolor="#4B76FF"> <mo>◦</mo> </mstyle> </mrow> </semantics> </math>) Gd-DTPA.</p> Full article ">Figure 6
<p><span class="html-italic">T</span><sub>1</sub><span class="html-italic">-</span>weighted (<b>left</b>) and <span class="html-italic">T</span><sub>2</sub>-weighted (<b>right</b>) magnetic resonance imaging (MRI) slices of GdSi aqueous solutions (0.1% xanthan gum), with varying Gd<sup>3+</sup> concentration, at magnetic field of 3 T and echo time of 2 ms (<span class="html-italic">T</span><sub>1</sub>) and 203 ms (<span class="html-italic">T</span><sub>2</sub>).</p> Full article ">Figure 7
<p><span class="html-italic">In vitro</span> 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cell viability assays in different cell lines incubated with variable concentrations of GdSi magnetic nanorods (mean ± SEM, <span class="html-italic">n</span> = 4). Top <span class="html-italic">X</span>-axis indicates the concentration of equivalent Gd<sup>3+</sup>.</p> Full article ">Figure 8
<p><span class="html-italic">In vivo</span> coronal <span class="html-italic">T</span><sub>1</sub>-weighted images acquired from a male Sprague-Dawley rat at 7 T magnetic field. (<b>a</b>,<b>c</b>) Control (baseline) with no MNP administration; (<b>b</b>,<b>d</b>) Acquisition 30 min after GdSi nanoparticles injection (0.04 mmol Gd<sup>3+</sup> kg<sup>−1</sup>); Red lines show up kidneys (<b>a</b>,<b>b</b>) and liver (<b>c</b>,<b>d</b>).</p> Full article ">Scheme 1
<p>Synthesis layout of Gd-Si oxide nanorods using Gd(H<sub>2</sub>O)<sub>4</sub>[Fe(CN)<sub>6</sub>] as a sacrificial template.</p> Full article ">
2603 KiB  
Article
A Flexible 360-Degree Thermal Sound Source Based on Laser Induced Graphene
by Lu-Qi Tao, Ying Liu, Zhen-Yi Ju, He Tian, Qian-Yi Xie, Yi Yang and Tian-Ling Ren
Nanomaterials 2016, 6(6), 112; https://doi.org/10.3390/nano6060112 - 7 Jun 2016
Cited by 20 | Viewed by 6801
Abstract
A flexible sound source is essential in a whole flexible system. It’s hard to integrate a conventional sound source based on a piezoelectric part into a whole flexible system. Moreover, the sound pressure from the back side of a sound source is usually [...] Read more.
A flexible sound source is essential in a whole flexible system. It’s hard to integrate a conventional sound source based on a piezoelectric part into a whole flexible system. Moreover, the sound pressure from the back side of a sound source is usually weaker than that from the front side. With the help of direct laser writing (DLW) technology, the fabrication of a flexible 360-degree thermal sound source becomes possible. A 650-nm low-power laser was used to reduce the graphene oxide (GO). The stripped laser induced graphene thermal sound source was then attached to the surface of a cylindrical bottle so that it could emit sound in a 360-degree direction. The sound pressure level and directivity of the sound source were tested, and the results were in good agreement with the theoretical results. Because of its 360-degree sound field, high flexibility, high efficiency, low cost, and good reliability, the 360-degree thermal acoustic sound source will be widely applied in consumer electronics, multi-media systems, and ultrasonic detection and imaging. Full article
(This article belongs to the Special Issue Nanomaterials for Flexible and Stretchable Devices: Synthesis, Processes, and Applications)
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<p>Fabrication process of the 360-degree thermal sound source.</p> Full article ">Figure 2
<p>Schematic illustration of the testing platform of 360-degree thermal sound source.</p> Full article ">Figure 3
<p>The morphology and structure of the laser induced graphene thermal sound source. (<b>a</b>) The flexible thermal sound source in hand. (<b>b</b>) The 360-degree thermal sound source attached to a cylindrical bottle. (<b>c</b>) The 360-degree thermal sound source attached to an ultrathin stick. (<b>d</b>) The surface profile of graphene oxide (GO) under scanning electron microscope (SEM). (<b>e</b>) The SEM image of laser induced graphene under low magnification. (<b>f</b>) The SEM image of laser induced graphene under high magnification.</p> Full article ">Figure 4
<p>The Raman spectrum of the graphene oxide (blue line) and laser induced graphene (red line).</p> Full article ">Figure 5
<p>Performance testing of the 360-degree thermal sound source. (<b>a</b>) The output sound pressure level <span class="html-italic">vs.</span> the frequency. (<b>b</b>) The directivity of the thermal sound source.</p> Full article ">Figure 6
<p>Simulation of the sound field for the device. (<b>a</b>) The sound field of horizontal plane of the device working at 20 kHz, showing great uniformity at 360 degrees. (<b>b</b>) The sound field of the vertical plane of the device working at 20 kHz. (<b>c</b>) The theoretical sound pressure level (SPL) <span class="html-italic">vs</span>. frequencies ranging from 100 Hz to 20 kHz.</p> Full article ">
3899 KiB  
Review
Selective Plasma Etching of Polymeric Substrates for Advanced Applications
by Harinarayanan Puliyalil and Uroš Cvelbar
Nanomaterials 2016, 6(6), 108; https://doi.org/10.3390/nano6060108 - 7 Jun 2016
Cited by 98 | Viewed by 13221
Abstract
In today’s nanoworld, there is a strong need to manipulate and process materials on an atom-by-atom scale with new tools such as reactive plasma, which in some states enables high selectivity of interaction between plasma species and materials. These interactions first involve preferential [...] Read more.
In today’s nanoworld, there is a strong need to manipulate and process materials on an atom-by-atom scale with new tools such as reactive plasma, which in some states enables high selectivity of interaction between plasma species and materials. These interactions first involve preferential interactions with precise bonds in materials and later cause etching. This typically occurs based on material stability, which leads to preferential etching of one material over other. This process is especially interesting for polymeric substrates with increasing complexity and a “zoo” of bonds, which are used in numerous applications. In this comprehensive summary, we encompass the complete selective etching of polymers and polymer matrix micro-/nanocomposites with plasma and unravel the mechanisms behind the scenes, which ultimately leads to the enhancement of surface properties and device performance. Full article
(This article belongs to the Special Issue Plasma Nanoengineering and Nanofabrication)
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<p>Schematic representation of various uses of different plasma processes.</p> Full article ">Figure 2
<p>Schematic representation of various plasma processing systems for (<b>a</b>) sputtering; (<b>b</b>) reactive ion etching; and (<b>c</b>) highly dissociated weakly ionized plasma for chemical etching.</p> Full article ">Figure 3
<p>(<b>a</b>) Scheme of the fabrication process of Teflon nanocone arrays; (<b>b</b>) Photograph showing a macroscopic view of flexible Teflon nanocone array; (<b>c</b>) Scanning electron microscopy (SEM) images of the tilted nanocone array. Inset: detailed view of Teflon nanocones (Reproduced with permission from [<a href="#B69-nanomaterials-06-00108" class="html-bibr">69</a>]. Copyright American Chemical Society, 2014).</p> Full article ">Figure 4
<p>The schematic of reaction involved in the radical quenching by the aromatic ring to form functional group instead of ring cleavage.</p> Full article ">Figure 5
<p>Atomic force microscopy (AFM) images of two small pieces of graphene (top: a monolayer (1 L) graphene strip; bottom: a few-layer graphene strip). (<b>a</b>) Before and (<b>b</b>) after selective hydrogen plasma edge etching for 60 min at 300 °C (Reproduced with permission from [<a href="#B76-nanomaterials-06-00108" class="html-bibr">76</a>]. Copyright American Chemical Society, 2010).</p> Full article ">Figure 6
<p>Etching rates for various polymer substrates in Ar plasma based on [<a href="#B81-nanomaterials-06-00108" class="html-bibr">81</a>].</p> Full article ">Figure 7
<p>General schematic of the etching rate for various types of polymeric materials in O<sub>2</sub> plasma. (<b>a</b>) Dependence of etching rate on the aliphatic/aromatic behavior of the monomer units; (<b>b</b>) Etching rate dependence on the crystallinity; (<b>c</b>) Functionality dependence of the polymer with etching rate.</p> Full article ">Figure 8
<p>SEM images of the density-controlled fabrication of polymer nanowire (NW) arrays of Kapton by covering the initial surface with (<b>a</b>) 0.75; (<b>b</b>) 1.5; (<b>c</b>) 3; (<b>d</b>) 4.5; (<b>e</b>) 10; and (<b>f</b>) 15 nm of Au before inductively coupled plasma (ICP) etching. The graph represents the length-controlled growth of NWs of polyethylene terephthalate (PET), Kapton film, Durafilm, polystyrene (PS), and polydimethyl siloxane (PDMS). The inset is a SEM image of a NW array on Durafilm after 30 min of etching (Reproduced with permission from [<a href="#B128-nanomaterials-06-00108" class="html-bibr">128</a>]. Copyright American Chemical Society, 2009).</p> Full article ">Figure 9
<p>Simultaneous plasma enhanced reactive ion synthesis and etching (SPERISE) process and Si nanocone formation mechanism. (<b>a</b>) Process flow of the nanomanufacturing process: Pseudo randomly distributed silicon oxybromide nanodots are synthesized on the planar silicon substrate surface in the first few seconds of the SPERISE process. The oxide nanodots grow to hemispheres by a phase-transition nucleation process and act as a protective nanomask for the simultaneous reactive ion etching of the silicon underneath. Depending on the growth rate of the oxide hemispheres and the crystalline structures of the silicon substrates, nanocones with different aspect ratios are formed. The silicon oxybromide nanohemispheres on top of the nanocones are removed by wet etching; (<b>b</b>) Detailed schematic drawing of the three typical stages in the SPERISE process: Bromine and oxygen reactive ions interact with silicon to form synthesized oxide hemisphere and dots (orange) and etched silicon cone structure (green). Both the illustrations and corresponding SEM images at (i) 0–15 s; (ii) 15 s–2 min; and (iii) 2–5 min in the SPERISE process manifest this unique nanomanufacturing method (Reproduced with permission from [<a href="#B129-nanomaterials-06-00108" class="html-bibr">129</a>]. Copyright American Chemical Society, 2011).</p> Full article ">Figure 10
<p>Plasma surface interaction of the glass-filled composite with corresponding SEM images for non-treated and plasma-treated samples for 60 s. The graph represents the variation of comparative tracking index (CTI) performance with plasma exposure time (Reproduced with permission from [<a href="#B101-nanomaterials-06-00108" class="html-bibr">101</a>]. Copyright Royal Society of Chemistry, 2015, Year.”).</p> Full article ">
2813 KiB  
Article
DNA Sequencing by Hexagonal Boron Nitride Nanopore: A Computational Study
by Liuyang Zhang and Xianqiao Wang
Nanomaterials 2016, 6(6), 111; https://doi.org/10.3390/nano6060111 - 6 Jun 2016
Cited by 40 | Viewed by 6622
Abstract
The single molecule detection associated with DNA sequencing has motivated intensive efforts to identify single DNA bases. However, little research has been reported utilizing single-layer hexagonal boron nitride (hBN) for DNA sequencing. Here we employ molecular dynamics simulations to explore pathways for single-strand [...] Read more.
The single molecule detection associated with DNA sequencing has motivated intensive efforts to identify single DNA bases. However, little research has been reported utilizing single-layer hexagonal boron nitride (hBN) for DNA sequencing. Here we employ molecular dynamics simulations to explore pathways for single-strand DNA (ssDNA) sequencing by nanopore on the hBN sheet. We first investigate the adhesive strength between nucleobases and the hBN sheet, which provides the foundation for the hBN-base interaction and nanopore sequencing mechanism. Simulation results show that the purine base has a more remarkable energy profile and affinity than the pyrimidine base on the hBN sheet. The threading of ssDNA through the hBN nanopore can be clearly identified due to their different energy profiles and conformations with circular nanopores on the hBN sheet. The sequencing process is orientation dependent when the shape of the hBN nanopore deviates from the circle. Our results open up a promising avenue to explore the capability of DNA sequencing by hBN nanopore. Full article
(This article belongs to the Special Issue Computational Modeling and Simulations of Carbon Nanomaterials)
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<p>Scheme of single-strand DNA (ssDNA) sequencing with hexagonal boron nitride (hBN) nanopore. The ssDNA is placed right above the hBN nanopore and perpendicular to the hBN sheet. The red, orange, pink and grey areas represent the adenine (A), thymine (T), cytosine (C) and guanine (G) nucleotides separately.</p> Full article ">Figure 2
<p>Evolution of binding energy between hBN and four basic nucleotides.</p> Full article ">Figure 3
<p>Evolution of binding energy between graphene and four basic nucleotides.</p> Full article ">Figure 4
<p>Contribution of van der Waals (vdW) and electrostatic interaction in the binding energy between hBN and four basic nucleotides.</p> Full article ">Figure 5
<p>Conformation of stretching process of ssDNA before passing through the hBN nanopore (<b>a</b>–<b>d</b>); Evolution of real-time process of passing-through the hBN nanopore (<b>e</b>–<b>h</b>); Evolution of real-time radius of gyration (<b>i</b>).</p> Full article ">Figure 6
<p>Hexagonal boron nitride (hBN) nanopores of different geometries and illustration of nucleotides passing through the nanopore: (<b>a</b>) circular nanopore; (<b>b</b>) elliptical nanopore.</p> Full article ">Figure 7
<p>Energy profile when ssDNA passed through the circular hBN nanopores. The energy peak values for different nucleotides are extracted from the energy profile.</p> Full article ">Figure 8
<p>Energy profile when ssDNA passes through the elliptical hBN nanopores. The energy peak values for different nucleotides are extracted from the energy profile.</p> Full article ">
9511 KiB  
Review
Complex-Morphology Metal-Based Nanostructures: Fabrication, Characterization, and Applications
by Antonella Gentile, Francesco Ruffino and Maria Grazia Grimaldi
Nanomaterials 2016, 6(6), 110; https://doi.org/10.3390/nano6060110 - 6 Jun 2016
Cited by 86 | Viewed by 11909
Abstract
Due to their peculiar qualities, metal-based nanostructures have been extensively used in applications such as catalysis, electronics, photography, and information storage, among others. New applications for metals in areas such as photonics, sensing, imaging, and medicine are also being developed. Significantly, most of [...] Read more.
Due to their peculiar qualities, metal-based nanostructures have been extensively used in applications such as catalysis, electronics, photography, and information storage, among others. New applications for metals in areas such as photonics, sensing, imaging, and medicine are also being developed. Significantly, most of these applications require the use of metals in the form of nanostructures with specific controlled properties. The properties of nanoscale metals are determined by a set of physical parameters that include size, shape, composition, and structure. In recent years, many research fields have focused on the synthesis of nanoscale-sized metallic materials with complex shape and composition in order to optimize the optical and electrical response of devices containing metallic nanostructures. The present paper aims to overview the most recent results—in terms of fabrication methodologies, characterization of the physico-chemical properties and applications—of complex-morphology metal-based nanostructures. The paper strongly focuses on the correlation between the complex morphology and the structures’ properties, showing how the morphological complexity (and its nanoscale control) can often give access to a wide range of innovative properties exploitable for innovative functional device production. We begin with an overview of the basic concepts on the correlation between structural and optical parameters of nanoscale metallic materials with complex shape and composition, and the possible solutions offered by nanotechnology in a large range of applications (catalysis, electronics, photonics, sensing). The aim is to assess the state of the art, and then show the innovative contributions that can be proposed in this research field. We subsequently report on innovative, versatile and low-cost synthesis techniques, suitable for providing a good control on the size, surface density, composition and geometry of the metallic nanostructures. The main purpose of this study is the fabrication of functional nanoscale-sized materials, whose properties can be tailored (in a wide range) simply by controlling the structural characteristics. The modulation of the structural parameters is required to tune the plasmonic properties of the nanostructures for applications such as biosensors, opto-electronic or photovoltaic devices and surface-enhanced Raman scattering (SERS) substrates. The structural characterization of the obtained nanoscale materials is employed in order to define how the synthesis parameters affect the structural characteristics of the resulting metallic nanostructures. Then, macroscopic measurements are used to probe their electrical and optical properties. Phenomenological growth models are drafted to explain the processes involved in the growth and evolution of such composite systems. After the synthesis and characterization of the metallic nanostructures, we study the effects of the incorporation of the complex morphologies on the optical and electrical responses of each specific device. Full article
(This article belongs to the Special Issue Semiconductor Core/Shell Nanocrystals for Optoelectronic Applications)
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<p>A summary of different shapes that have been achieved for various metal nanocrystals. Reproduced with permission from [<a href="#B2-nanomaterials-06-00110" class="html-bibr">2</a>]. Copyright Wiley, 2008.</p> Full article ">Figure 2
<p>(<b>a</b>) Scattering spectra of single silver nanoparticles of different shapes obtained in dark-field configuration. Optical dark field images together with scanning electron microscope (SEM) images of individual gold nanoparticles (<b>b</b>) and corresponding scattering spectra (<b>c</b>) for an incident light polarization along the long particle axis. (<b>a</b>) Reproduced with permission from [<a href="#B59-nanomaterials-06-00110" class="html-bibr">59</a>]. Copyright American Institute of Physics, 2002. (<b>b</b>,<b>c</b>) reproduced with permission from [<a href="#B60-nanomaterials-06-00110" class="html-bibr">60</a>]. Copyright American Institute of Physics, 2003.</p> Full article ">Figure 3
<p>Simulated intensity distribution of the optical near-field above an ensemble of well-separated gold particles (<b>a</b>) and a chain of closely spaced gold nanoparticles (<b>b</b>). While for separated particles interference effects of the scattered fields are visible, in the particle chain, the fields are closely confined in gaps between adjacent particles. Plasmon resonances were excited using prism coupling with the direction of the in-plane moment component as outlined in the pictures. Reproduced with permission from [<a href="#B61-nanomaterials-06-00110" class="html-bibr">61</a>]. Copyright Wiley, 2001.</p> Full article ">Figure 4
<p>Extinction spectra for square two-dimensional gratings of gold nanoparticles (height 14 nm, diameter 150 nm) with grating constant d situated on a glass substrate. Reproduced with permission from [<a href="#B63-nanomaterials-06-00110" class="html-bibr">63</a>]. Copyright American Physical Society, 2000.</p> Full article ">Figure 5
<p>SEM images of gold nanorings and nanodisks prepared by colloidal lithography. (<b>a</b>) 80° tilt image of a ring structure. The walls of the rings are thin enough for the 30 keV electrons to pass through; (<b>b</b>,<b>c</b>) Top views of disks and rings taken at an acceleration voltage of 1.5 keV. The heights of the disks and rings in the figure are <b>≈</b>20 and <b>≈</b>40 nm, respectively, whereas the radius is <b>≈</b>60 nm in both cases. The thickness of the ring walls was estimated at 14 ± 2 nm from sideview SEM images similar to (<b>a</b>); (<b>d</b>) Experimental extinction spectra of disks (<span class="html-italic">d</span>, dashed line) and rings (<span class="html-italic">r</span>, solid lines). The estimated wall thickness d of the rings is <span class="html-italic">d</span> = 14 ± 2 nm (<span class="html-italic">r</span><sub>1</sub>), d <span class="html-italic">=</span> 10 ± 2 nm (<span class="html-italic">r</span><sub>2</sub>), and d = 9 ± 2 nm (<span class="html-italic">r</span><sub>3</sub>), respectively. (<b>d</b>) Calculated extinction spectra for the same particles as in (<b>a</b>). The rings exhibit near-infrared features at larger wavelengths for thinner walls. The disks show a dipolar excitation at around 700 nm. Reproduced with permission from [<a href="#B69-nanomaterials-06-00110" class="html-bibr">69</a>]. Copyright American Physical Society, 2003.</p> Full article ">Figure 6
<p>(<b>A</b>) Schematics of the fabrication of hematite-Au core-shell nanorice particles. SEM (<b>left</b>) and transmission electron microscopy (TEM) (<b>right</b>) images of (<b>B</b>) hematite core (longitudinal diameter of 340 ± 20 nm, and transverse diameter of 54 ± 4 nm; (<b>C</b>) seed particles; (<b>D</b>) nanorice particles with thin shells (13.1 ± 1.1 nm); and (<b>E</b>) nanorice particles with thick shells (27.5 ± 1.7 nm). Reproduced with permission from [<a href="#B73-nanomaterials-06-00110" class="html-bibr">73</a>]. Copyright American Chemical Society, 2006.</p> Full article ">Figure 7
<p>(<b>A</b>) Extinction spectra of hematite-Au core-shell nanorice with different shell thicknesses. Two plasmon peaks are observed for each sample. The plasmons at longer and shorter wavelengths are the longitudinal and transverse plasmons, respectively. The samples measured are monolayers of isolated nanoshells immobilized on polyvinylpyridine (PVP)-glass slides; (<b>B</b>) A SEM image of a monolayer of nanorice particles (shell thickness of 13.1 (1.1 nm) on a PVP-glass slide; (<b>C</b>) Calculated far-field extinction spectra of the nanorice with incident polarization along the longitudinal and (inset) transverse axis of a nanorice particle using finite difference time domain (FDTD). The nanorice particle employed for the FDTD simulations is composed of a hematite core with longitudinal diameter of 340 nm and transverse diameter of 54 nm surrounded by a 13-nm-thick Au shell. Near-field profile of the nanorice under resonance excitations: (<b>D</b>) incident polarization along the longitudinal axis, λ<sub>ex</sub> = 1160 nm; (<b>E</b>) incident polarization along the transverse axis, λ<sub>ex</sub> = 860 nm. Reproduced with permission from [<a href="#B73-nanomaterials-06-00110" class="html-bibr">73</a>]. Copyright American Chemical Society, 2006.</p> Full article ">Figure 8
<p>SEM micrographs of NPG synthesized by means of corrosion for 5 min (<b>a</b>) and 24 h (<b>b</b>); (<b>c</b>) ultraviolet (UV)-vis extinction spectra and (<b>d</b>) the resonant peak position of λ<sub>1</sub> and λ<sub>2</sub> of NPG with the pore sizes of 10–50 nm in water. For comparison, the dashed line represents the size dependence resonant band of gold nanoparticles. UV-vis extinction spectra of porous gold films with (<b>e</b>) 10 nm; (<b>f</b>) 30 nm; and (<b>g</b>) 50 nm are recorded by immersing them into various dielectric environments. Refractive index of these solutions increase from left to right: water (<span class="html-italic">n</span> = 1.33), ethanol (<span class="html-italic">n</span> = 1.36), 3:1 ethanol/toluene (<span class="html-italic">n</span> = 1.39), 1:1 ethanol/toluene (<span class="html-italic">n</span> = 1.429), 1:3 ethanol/toluene (<span class="html-italic">n</span> = 1.462), and toluene (<span class="html-italic">n</span> = 1.495). (d) Dependence of resonance (λ<sub>1</sub>), empty symbols and LSPR (λ<sub>2</sub>, solid symbols) peaks of NPG films on refractive index. Reproduced with permission from [<a href="#B97-nanomaterials-06-00110" class="html-bibr">97</a>]. Copyright American Institute of Physics, 2011.</p> Full article ">Figure 9
<p>Representative SEM micrographs of nanoporous gold with various nanopore sizes. (<b>a</b>) Nanoporous gold film after 5 min dealloying at room temperature; (<b>b</b>) dealloyed at room temperature for 48 h; (<b>c</b>) thoroughly rinsed nanoporous gold annealed at 200 °C for 2 h; (<b>d</b>) 400 °C for 2 h; (<b>e</b>) 500 °C for 2 h; and (<b>f</b>) 600 °C for 2 h. SERS spectra of nanoporous gold with different pore sizes for (<b>g</b>) 10<sup>−7</sup> mol/L R6G aqueous solution and (<b>h</b>) 10<sup>−5</sup> mol/L crystal violet (CV) methanol solution. Reproduced with permission from [<a href="#B96-nanomaterials-06-00110" class="html-bibr">96</a>]. Copyright American Institute of Physics, 2007.</p> Full article ">Figure 10
<p>Resistance (dots are the experimental data) of a growing gold film on glass as a function of volume (or area) fraction f of gold. Images included show characteristic morphology at each stage of gold coverage. Reproduced with permission from [<a href="#B107-nanomaterials-06-00110" class="html-bibr">107</a>]. Copyright American Physical Society, 2008.</p> Full article ">Figure 11
<p>SEM images (false color) at 25° tilt of the perfectly ordered array of the nanoporous gold nanoparticles formed from the 15 nm Au/30 nm Ag bilayers. Reproduced with permission from [<a href="#B112-nanomaterials-06-00110" class="html-bibr">112</a>]. Copyright Beilstein-Institut, 2012.</p> Full article ">Figure 12
<p>Cross-sectional SEM micrographs showing the morphological evolution of Au–Cu nanowires with an initial Au content of 11 atomic % and a diameter of 200 nm as a function of the dealloying time and potential. Different dealloying potentials were explored: (<b>a</b>–<b>c</b>) 0.2; (<b>d</b>–<b>f</b>) 0.3; and (<b>g</b>–<b>i</b>) 0.4 V. Scale bar: 100 nm. Reproduced with permission from [<a href="#B113-nanomaterials-06-00110" class="html-bibr">113</a>]. Copyright American Chemical Society, 2016.</p> Full article ">Figure 13
<p>Dendritic structures obtained by electrochemical deposition of copper. (<b>a</b>) From 0.5 M CuSO<sub>4</sub>/0.5 M H<sub>2</sub>SO<sub>4</sub> at 350 mV (frame width = 2.5 mm); and (<b>b</b>) from 0.5 M CuCl<sub>2</sub> /0.5 M H<sub>2</sub>SO<sub>4</sub> at 500 mV (frame width = 0.6 mm). Reproduced with permission from [<a href="#B114-nanomaterials-06-00110" class="html-bibr">114</a>]. Copyright American Physical Society, 1995.</p> Full article ">Figure 14
<p>UV-vis absorption spectrum of Au nanodendrites. The inset shows the Au nanodendrites grown in mixed dodecyltrimethylammonium bromide/β-cyclodextrin solution. Reproduced with permission from [<a href="#B138-nanomaterials-06-00110" class="html-bibr">138</a>]. Copyright American Chemical Society, 2010.</p> Full article ">Figure 15
<p>UV-vis absorption spectra of the samples: (<b>a</b>) Ag B, 0.3 M aqueous NH<sub>3</sub> solution; (<b>b</b>) Ag C, 0.6 M aqueous NH<sub>3</sub> solution and (<b>c</b>) Ag D, 1.2 M aqueous NH<sub>3</sub> solution. The inset reports the simulated absorption spectrum from the Mie theory for the samples. Reproduced with permission from [<a href="#B139-nanomaterials-06-00110" class="html-bibr">139</a>]. Copyright Institute of Physics, 2007.</p> Full article ">Figure 16
<p>(<b>a</b>) Large-scale SEM image and (<b>b</b>) magnified image of silver nano-dendrites; (<b>c</b>) typical TEM image of C<sub>60</sub> nanoclusters coupled with silver dendrite. The inset shows a schematic SERS process; light is coupled with a plasmon leading to an interaction and this is then Raman scattered by C<sub>60</sub> nanoclusters on the surface of silver dendrite, and the outgoing plasmon is then scattered back into a photon; (<b>d</b>) SERS spectrum of C<sub>60</sub> nanoclusters coupled with silver dendrites from a solution of 1 mM C<sub>60</sub> in toluene. The Raman spectrum at the bottom corresponds to the sample of C<sub>60</sub> nanoclusters coupled with Si wafer from 1 mM C<sub>60</sub> toluene solution. Reproduced with permission from [<a href="#B143-nanomaterials-06-00110" class="html-bibr">143</a>]. Copyright Institute of Physics, 2009.</p> Full article ">Figure 17
<p>Temperature-dependent cathodoluminescent spectra of gold nano-peapodded silica nanowires. The inset shows the corresponding Fourier transform infrared spectroscopy (FTIR) spectrum. Reproduced with permission from [<a href="#B145-nanomaterials-06-00110" class="html-bibr">145</a>]. Copyright Nature Publishing Group, 2006.</p> Full article ">Figure 18
<p>Optical absorption spectra for plain silica nanowires (dotted line), gold peapodded silica nanowires (solid line) and gold-filled silica nanowires wherein the aspect ratio of the gold segment is about 3–5 (dashed line). Reproduced with permission from [<a href="#B145-nanomaterials-06-00110" class="html-bibr">145</a>]. Copyright Nature Publishing Group, 2006.</p> Full article ">Figure 19
<p>(<b>a</b>) TEM images showing the structure of metal nanoparticle-encapsulated silicon dioxide nanowire. The inset in in (<b>a</b>) shows an electron-diffraction pattern recorded along the [<a href="#B120-nanomaterials-06-00110" class="html-bibr">120</a>] zone axis; (<b>b</b>) Photoresponse measurements. The room-temperature resistance response as a function of time to light illumination for plain silica nanowires (<b>upper</b> part) and gold nanopeapodded silica nanowires (<b>lower</b> part). Shaded (pink, excitation wavelength lex = 635 nm; green, lex = 532 nm; purple, lex = 405 nm) and unshaded regions mark the light-on and light-off periods. Reproduced with permission from [<a href="#B145-nanomaterials-06-00110" class="html-bibr">145</a>]. Copyright Nature Publishing Group, 2006.</p> Full article ">Figure 20
<p>Field-emission scanning electron microscopy images of nanowire (NW) devices consisting of (<b>a</b>) plain silica NW (without the Au NPs) and (<b>b</b>) Au NPs-silica NW; (<b>c</b>) Dark I–V characteristics of single NW devices, with and without Au NP peapods, measured in vacuum, and the corresponding linear fit to the dataset; (<b>d</b>) Dark and photocurrent measured under vacuum in single NW devices, with and without Au NP peapods, as a function of time. The color bars indicate the duration of the 532 nm illumination. The measurement has been performed with a 1 V applied bias at room temperature. The bare silica NW showed no photoresponse, whereas the Au NPs-silica NW showed strong photoresponse. Reproduced with permission from [<a href="#B146-nanomaterials-06-00110" class="html-bibr">146</a>]. Copyright Nature Publishing Group, 2013.</p> Full article ">Figure 21
<p>Picture of a possible complex-morphology Au nanostructure (plan-view) crossing the properties of Au nanorings with the properties of sharp Au tips typical of nanodendritic structures.</p> Full article ">Figure 22
<p>Picture of a possible nanoporous Au nanodendrites.</p> Full article ">Figure 23
<p>Picture of a possible branched silica nanowires embedded with Au nanoparticles.</p> Full article ">
4183 KiB  
Article
Fe3+-Doped TiO2 Nanotube Arrays on Ti-Fe Alloys for Enhanced Photoelectrocatalytic Activity
by Jiangdong Yu, Zhi Wu, Cheng Gong, Wang Xiao, Lan Sun and Changjian Lin
Nanomaterials 2016, 6(6), 107; https://doi.org/10.3390/nano6060107 - 6 Jun 2016
Cited by 25 | Viewed by 7847
Abstract
Highly ordered, vertically oriented Fe3+-doped TiO2 nanotube arrays (Fe-TNTs) were prepared on Ti-Fe alloy substrates with different Fe contents by the electrochemical anodization method. The as-prepared Fe-TNTs were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction [...] Read more.
Highly ordered, vertically oriented Fe3+-doped TiO2 nanotube arrays (Fe-TNTs) were prepared on Ti-Fe alloy substrates with different Fe contents by the electrochemical anodization method. The as-prepared Fe-TNTs were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and related electrochemical techniques. XPS results demonstrated that Fe3+ ions were successfully doped into TiO2 nanotubes. The photoelectrochemical activity of Fe-TNTs was compared with that of pure TiO2 nanotube arrays (TNTs). The results showed that Fe-TNTs grown on low concentration (0.5 wt %–1 wt % Fe) Ti-Fe alloys possessed higher photocurrent density than TNTs. The Fe-TNTs grown on Ti-Fe alloy containing 0.8 wt % Fe exhibited the highest photoelectrochemical activity and the photoelectrocatalytic degradation rate of methylene blue (MB) aqueous solution was significantly higher than that of TNTs. Full article
(This article belongs to the Special Issue Nanomaterials for Electrocatalysis)
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<p>Top-view scanning electron microscope (SEM) images of the nanotube arrays grown on (<b>a</b>) Ti; (<b>b</b>) Ti05Fe; (<b>c</b>) Ti08Fe; (<b>d</b>) Ti10Fe; (<b>e</b>) Ti50Fe and (<b>f</b>) energy dispersive spectrum (EDS) pattern of Ti08Fe. The insets were the corresponding cross-sectional images.</p> Full article ">Figure 2
<p>Transmission electron microscopy (TEM) images of Fe-TNTs based on Ti08Fe: (<b>a</b>) low magnification of top-view image; (<b>b</b>) low magnification of cross-section-view image; (<b>c</b>) high magnification of cross-section-view image; and (<b>d</b>) HRTEM image. TNTs: TiO<sub>2</sub> nanotube arrays (TNTs).</p> Full article ">Figure 3
<p>X-ray diffraction (XRD) patterns of the nanotube arrays grown on Tiand different Ti-Fe alloys.</p> Full article ">Figure 4
<p>X-ray photoelectron spectroscopy (XPS) survey spectrum of Fe-TNTs (<b>a</b>) and high resolution XPS spectra of Fe 2p (<b>b</b>); Ti 2p (<b>c</b>) and O 1s (<b>d</b>) of Fe-TNTs.</p> Full article ">Figure 5
<p>UV-vis diffuse reflectance spectra of TNTs and Fe-TNTs prepared by anodizing Ti-Fe alloys with different Fe content.</p> Full article ">Figure 6
<p>(<b>a</b>) <span class="html-italic">J</span>-<span class="html-italic">V</span> and (<b>b</b>) <span class="html-italic">J</span>-<span class="html-italic">t</span> curves with a bias of 0.6 V for all samples under Xe lamp irradiation.</p> Full article ">Figure 7
<p>Electrochemical impedance spectroscopy (EIS) Nyquist plots for TNTs and Fe-TNTs prepared by anodizing Ti08Fe alloy under Xe lamp irradiation.</p> Full article ">Figure 8
<p>(<b>a</b>) UV-vis absorption spectra of methylene blue (MB) solution photoelectrodegraded by Ti08Fe and (<b>b</b>) MB degradation kinetic curves of TNTs and Fe-TNTs.</p> Full article ">Figure 9
<p>Schematic illustrating the separation and transport of charge carriers in the process of photoelectrocatalytic degradation over Fe-TNTs.</p> Full article ">Figure 10
<p>Schematic diagram of a photoelectrochemical cell for photoelectrocatalytic degradation of organic pollutant by capitalizing on Fe-TNTs (or TNTs) as working electrode, Pt as counter electrode, and saturated calomel electrode (SCE) as the reference electrode, respectively.</p> Full article ">
150 KiB  
Editorial
Engineered Nanomaterials in the Environment
by Jonathan D. Judy and Paul Bertsch
Nanomaterials 2016, 6(6), 106; https://doi.org/10.3390/nano6060106 - 6 Jun 2016
Cited by 3 | Viewed by 3870
Abstract
This Special Issue of Nanomaterials, “Engineered Nanomaterials in the Environment”, is comprised of one communication and five research articles.[...] Full article
(This article belongs to the Special Issue Engineered Nanomaterials in the Environment)
147 KiB  
Editorial
Nanoparticles in Bioimaging
by Yurii K. Gun’ko
Nanomaterials 2016, 6(6), 105; https://doi.org/10.3390/nano6060105 - 6 Jun 2016
Cited by 24 | Viewed by 4763
Abstract
This Special Issue of Nanomaterials is dedicated to the application of nanoparticulate materials in biological imaging.[...] Full article
(This article belongs to the Special Issue Nanoparticles in Bioimaging)
1751 KiB  
Article
The Influence of Modified Silica Nanomaterials on Adult Stem Cell Culture
by Luigi Tarpani, Francesco Morena, Marta Gambucci, Giulia Zampini, Giuseppina Massaro, Chiara Argentati, Carla Emiliani, Sabata Martino and Loredana Latterini
Nanomaterials 2016, 6(6), 104; https://doi.org/10.3390/nano6060104 - 4 Jun 2016
Cited by 20 | Viewed by 5241
Abstract
The preparation of tailored nanomaterials able to support cell growth and viability is mandatory for tissue engineering applications. In the present work, silica nanoparticles were prepared by a sol-gel procedure and were then functionalized by condensation of amino groups and by adsorption of [...] Read more.
The preparation of tailored nanomaterials able to support cell growth and viability is mandatory for tissue engineering applications. In the present work, silica nanoparticles were prepared by a sol-gel procedure and were then functionalized by condensation of amino groups and by adsorption of silver nanoparticles. Transmission electron microscopy (TEM) imaging was used to establish the morphology and the average dimensions of about 130 nm, which were not affected by the functionalization. The three silica samples were deposited (1 mg/mL) on cover glasses, which were used as a substrate to culture adult human bone marrow-mesenchymal stem cells (hBM-MSCs) and human adipose-derived stem cells (hASCs). The good cell viability over the different silica surfaces was evaluated by monitoring the mitochondrial dehydrogenase activity. The analysis of the morphological parameters (aspect ratio, cell length, and nuclear shape Index) yielded information about the interactions of stem cells with the surface of three different nanoparticles. The data are discussed in terms of chemical properties of the surface of silica nanoparticles. Full article
(This article belongs to the Special Issue Nanomaterials for Tissue Engineering)
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<p>Transmission electron microscopy (TEM) images of SiO<sub>2</sub> (<b>a</b>), inset size distribution histogram), N-SiO<sub>2</sub> (<b>b</b>), and Ag-SiO<sub>2</sub> (<b>c</b>), inset: TEM image of dodecanethiol-stabilized silver nanoparticles (DDT-Ag nanoparticles); (<b>d</b>) Atomic force microscopy (AFM) image of SiO<sub>2</sub> nanoparticles deposited on cover glass after washing procedure. Scale bars are 200 nm.</p> Full article ">Figure 2
<p>Stem cell viability on surfaces of SiO<sub>2</sub>, N-SiO<sub>2</sub>, and Ag-SiO<sub>2</sub> nanoparticles: (<b>a</b>) (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) viability assay of human bone marrow-mesenchymal stem cells (hBM-MSCs) on different nanoparticles at 3, 7, and 14 days; (<b>b</b>) MTT viability assay of hASCs on different nanoparticles at 3, 7, and 14 days.</p> Full article ">Figure 3
<p>Interaction adult hBM-MSCs with nanoparticles: Immunofluorescence of hBM-MSCs seeded on (<b>a</b>) SiO<sub>2</sub>; (<b>b</b>) N-SiO<sub>2</sub>; (<b>c</b>) Ag-SiO<sub>2</sub>; (<b>d</b>) Control culture. Fluorescein isothiocyanate)-Phalloidin (FITC): F-actin; 4′,6-Diamidino-2-Phenylindole, Dihydrochloride (DAPI): nuclei. (<b>e</b>) Nuclear shape Index; (<b>f</b>) aspect ratio; (<b>g</b>) cell length. See method section for details.</p> Full article ">Figure 4
<p>Interaction adult hASCs with nanoparticles: Immunofluorescence of hASCs seeded on (<b>a</b>) SiO<sub>2</sub>; (<b>b</b>) N-SiO<sub>2</sub>; (<b>c</b>) Ag-SiO<sub>2</sub>; (<b>d</b>) Control culture. FITC-phalloidin: F-actin; DAPI: nuclei. (<b>e</b>) Nuclear shape Index; (<b>f</b>) aspect ratio; (<b>g</b>) cell length. See method section for details.</p> Full article ">
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Article
Enhanced Activity of Supported Ni Catalysts Promoted by Pt for Rapid Reduction of Aromatic Nitro Compounds
by Huishan Shang, Kecheng Pan, Lu Zhang, Bing Zhang and Xu Xiang
Nanomaterials 2016, 6(6), 103; https://doi.org/10.3390/nano6060103 - 4 Jun 2016
Cited by 42 | Viewed by 6317
Abstract
To improve the activities of non-noble metal catalysts is highly desirable and valuable to the reduced use of noble metal resources. In this work, the supported nickel (Ni) and nickel-platinum (NiPt) nanocatalysts were derived from a layered double hydroxide/carbon composite precursor. The catalysts [...] Read more.
To improve the activities of non-noble metal catalysts is highly desirable and valuable to the reduced use of noble metal resources. In this work, the supported nickel (Ni) and nickel-platinum (NiPt) nanocatalysts were derived from a layered double hydroxide/carbon composite precursor. The catalysts were characterized and the role of Pt was analysed using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDS) mapping, and X-ray photoelectron spectroscopy (XPS) techniques. The Ni2+ was reduced to metallic Ni0 via a self-reduction way utilizing the carbon as a reducing agent. The average sizes of the Ni particles in the NiPt catalysts were smaller than that in the supported Ni catalyst. The electronic structure of Ni was affected by the incorporation of Pt. The optimal NiPt catalysts exhibited remarkably improved activity toward the reduction of nitrophenol, which has an apparent rate constant (Ka) of 18.82 × 10−3 s−1, 6.2 times larger than that of Ni catalyst and also larger than most of the reported values of noble-metal and bimetallic catalysts. The enhanced activity could be ascribed to the modification to the electronic structure of Ni by Pt and the effect of exposed crystal planes. Full article
(This article belongs to the Special Issue Nanoparticles for Catalysis)
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<p>X-ray diffraction (XRD) patterns of (<b>a</b>) layered double hydroxide (LDH), LDH/carbon (C), and Pt@LDH/C; (<b>b</b>) NiPt catalysts obtained at different calcination temperatures; and (<b>c</b>) the Ni and NiPt catalysts with different Pt loadings.</p> Full article ">Figure 2
<p>Transmission electron microscopy (TEM) images and size distributions of the supported Ni and NiPt catalysts with different Pt loadings (<b>a</b>) and (<b>b</b>) Ni; (<b>c</b>) and (<b>d</b>) NiPt-0.2%; (<b>e</b>) and (<b>f</b>) NiPt-0.6%; (<b>g</b>) and (<b>h</b>) NiPt-1.0%.</p> Full article ">Figure 3
<p>High-resolution transmission electron microscopy (HRTEM) images of the supported catalysts: (<b>a</b>) Ni; (<b>b</b>) NiPt-0.2%; (<b>c</b>) NiPt-0.6%; (<b>d</b>) NiPt-1.0%; (<b>e</b>) Energy dispersive X-ray spectroscopy (EDS) mapping of the catalyst NiPt-0.6%.</p> Full article ">Figure 4
<p>X-ray photoelectron spectroscopy (XPS) spectra of Pt and Ni core levels in the supported catalysts: (<b>a</b>) NiPt-0.2%; (<b>b</b>) NiPt-0.6%; (<b>c</b>) NiPt-1.0% and (<b>d</b>) Ni.</p> Full article ">Figure 5
<p>(<b>a</b>) Ultraviolet-visible (UV-VIS) absorption spectra of the solution before (i) and after (ii) the addition of NaBH<sub>4</sub> and (iii) after the addition of NiPt-0.6% catalyst; (<b>b</b>) time-dependent UV-VIS absorption spectra of the reduction of 4-NP over the NiPt-0.6% catalyst in aqueous solution at room temperature; (<b>c</b>) reduction of 4-NP over different catalysts as a function of time; (<b>d</b>) apparent rate constants (<span class="html-italic">K<sub>a</sub></span>) of the reactions in the presence of supported catalysts.</p> Full article ">Figure 6
<p>Reaction pathways for the reduction of 4-NP to 4-AP: (<b>a</b>) NaBH<sub>4</sub> hydrolyzed to release H<sub>2</sub>; (<b>b</b>) H<sub>2</sub> molecules split to H atoms on the surface of metal NPs and reacted with 4-NP; (<b>c</b>) H atoms reacted with the nitrosophenol intermediate to form hydroxylamine; (<b>d</b>) hydroxylamine was further reduced to the final product 4-AP. H–M–H represents the split of H<sub>2</sub> molecules on the surface of metal NPs.</p> Full article ">Figure 7
<p>Separation of NiPt-0.6% from solution by a magnet: (<b>a</b>) before addition of the catalyst; (<b>b</b>) after addition of the catalyst; (<b>c</b>) the suspension solution after reaction; (<b>d</b>) separation of solid catalysts with a magnet.</p> Full article ">
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Article
Fluorescent Nanocomposite of Embedded Ceria Nanoparticles in Crosslinked PVA Electrospun Nanofibers
by Nader Shehata, Soha Gaballah, Effat Samir, Aya Hamed and Marwa Saad
Nanomaterials 2016, 6(6), 102; https://doi.org/10.3390/nano6060102 - 1 Jun 2016
Cited by 12 | Viewed by 4856
Abstract
This paper introduces a new fluorescent nanocomposite of electrospun biodegradable nanofibers embedded with optical nanoparticles. In detail, this work introduces the fluorescence properties of PVA nanofibers generated by the electrospinning technique with embedded cerium oxide (ceria) nanoparticles. Under near-ultra violet excitation, the synthesized [...] Read more.
This paper introduces a new fluorescent nanocomposite of electrospun biodegradable nanofibers embedded with optical nanoparticles. In detail, this work introduces the fluorescence properties of PVA nanofibers generated by the electrospinning technique with embedded cerium oxide (ceria) nanoparticles. Under near-ultra violet excitation, the synthesized nanocomposite generates a visible fluorescent emission at 520 nm, varying its intensity peak according to the concentration of in situ embedded ceria nanoparticles. This is due to the fact that the embedded ceria nanoparticles have optical tri-valiant cerium ions, associated with formed oxygen vacancies, with a direct allowed bandgap around 3.5 eV. In addition, the impact of chemical crosslinking of the PVA on the fluorescence emission is studied in both cases of adding ceria nanoparticles in situ or of a post-synthesis addition via a spin-coating mechanism. Other optical and structural characteristics such as absorbance dispersion, direct bandgap, FTIR spectroscopy, and SEM analysis are presented. The synthesized optical nanocomposite could be helpful in different applications such as environmental monitoring and bioimaging. Full article
(This article belongs to the Special Issue Multifunctional Polymer-Based Nanocomposites)
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<p>Poly(vinyl alcohol) (PVA) nanofibers (NFs) with <span class="html-italic">in situ</span> embedded cerium oxide nanoparticles (ceria NPs):(<b>a</b>) Absorbance curve;(<b>b</b>) Bandgap curve.</p> Full article ">Figure 2
<p>Fluorescence intensity PVA NFs with <span class="html-italic">in situ</span> embedded different concentrations of ceria NPs.</p> Full article ">Figure 3
<p>(<b>a</b>) TEM of ceria NPs and (<b>b</b>) SEM of nanofibers with embedded ceria with the arrows showing the agglomerated parts of ceria NPs over the PVA nanofibers.</p> Full article ">Figure 4
<p>(<b>a</b>) The absorbance dispersion of crosslinked PVA NFs with <span class="html-italic">in situ</span> embedded different concentrations of ceria NPs, and (<b>b</b>) the corresponding direct allowed bandgap.</p> Full article ">Figure 5
<p>(<b>a</b>) The absorbance dispersion of spin-coated ceria NPs at 1 wt % on crosslinked PVA NFs, and (<b>b</b>) the corresponding allowed direct bandgap.</p> Full article ">Figure 6
<p>(<b>a</b>) Fluorescence intensity of crosslinked PVA NFs with <span class="html-italic">in situ</span> embedded different concentrations of ceria NPs; (<b>b</b>) Fluorescence intensity after immersing the crosslinked fiber in water.</p> Full article ">Figure 7
<p>(<b>a</b>) Fluorescence intensity of spin-coated ceria NPs on crosslinked PVA NFs and (<b>b</b>) SEM image of the crosslinked PVA NFs.</p> Full article ">Figure 8
<p>FTIR spectroscopy pattern of crosslinked PVA with embedded ceria NPs.</p> Full article ">Figure 9
<p>Schematic diagram of the electrospinning setup.</p> Full article ">Figure 10
<p>Fluorescence intensity spectroscopy setup.</p> Full article ">
2423 KiB  
Article
TiAl3-TiN Composite Nanoparticles Produced by Hydrogen Plasma-Metal Reaction: Synthesis, Passivation, and Characterization
by Ju Ying Li and Qing Song Mei
Nanomaterials 2016, 6(6), 101; https://doi.org/10.3390/nano6060101 - 1 Jun 2016
Cited by 1 | Viewed by 4785
Abstract
TiAl3 and TiN composite nanoparticles were continuously synthesized from Ti–48Al master alloy by hydrogen plasma-metal reaction in a N2, H2 and Ar atmosphere. The phase, morphology, and size of the nanoparticles were studied by X-ray diffraction (XRD) and transmission [...] Read more.
TiAl3 and TiN composite nanoparticles were continuously synthesized from Ti–48Al master alloy by hydrogen plasma-metal reaction in a N2, H2 and Ar atmosphere. The phase, morphology, and size of the nanoparticles were studied by X-ray diffraction (XRD) and transmission electronic microscopy (TEM). X-ray photoelectron spectroscopy (XPS) and evolved gas analysis (EGA) were used to analyze the surface phase constitution and oxygen content of the nanoparticles. The as-synthesized nanopowders were mainly composed of nearly spherical TiAl3 and tetragonal TiN phases, with a mean diameter of ~42 nm and mass fractions of 49.1% and 24.3%, respectively. Passivation in the atmosphere of Ar and O2 for 24 h at room temperature led to the formation of amorphous Al2O3 shells on the TiAl3 particle surface, with a mean thickness of ~5.0 nm and a mass fraction of ~23.5%, as well as TiO2 with a mass fraction of ~3.2%. Full article
(This article belongs to the Special Issue Plasma Nanoengineering and Nanofabrication)
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<p>(<b>a</b>) and (<b>b</b>) Typical bright-field transmission electron microscope (TEM) micrographs of the nanoparticles synthesized from the master alloy of Ti–48Al by hydrogen plasma-metal reaction (HPMR) in N<sub>2</sub>, H<sub>2</sub>, and Ar atmosphere; (<b>c</b>) particle size distribution.</p> Full article ">Figure 2
<p>X-ray diffraction analysis (XRD) pattern of the nanoparticles synthesized from the master alloy of Ti–48Al by HPMR in N<sub>2</sub>, H<sub>2</sub>, and Ar atmosphere.</p> Full article ">Figure 3
<p>(<b>a</b>) X-ray photoelectron spectroscopy (XPS) patterns of the nanoparticles synthesized from the master alloy of Ti–48Al by HPMR in N<sub>2</sub>, H<sub>2</sub>, and Ar atmosphere; (<b>b</b>–<b>d</b>) are the enlargements corresponding to different ranges of binding energy.</p> Full article ">Figure 4
<p>(<b>a</b>) Release curve of oxygen in the passivated nanopowders synthesized from the master alloy of Ti–48Al by HPMR in N<sub>2</sub>, H<sub>2</sub>, and Ar atmosphere; (<b>b</b>) the amplification in the time range of 0–110 s.</p> Full article ">Figure 5
<p>High resolution transmission electron microscopy (HRTEM) micrograph of the passivated TiAl<sub>3</sub> nanoparticle showing the surface oxide.</p> Full article ">
2549 KiB  
Article
Fabricating Water Dispersible Superparamagnetic Iron Oxide Nanoparticles for Biomedical Applications through Ligand Exchange and Direct Conjugation
by Tina Lam, Pramod K. Avti, Philippe Pouliot, Foued Maafi, Jean-Claude Tardif, Éric Rhéaume, Frédéric Lesage and Ashok Kakkar
Nanomaterials 2016, 6(6), 100; https://doi.org/10.3390/nano6060100 - 26 May 2016
Cited by 28 | Viewed by 8674
Abstract
Stable superparamagnetic iron oxide nanoparticles (SPIONs), which can be easily dispersed in an aqueous medium and exhibit high magnetic relaxivities, are ideal candidates for biomedical applications including contrast agents for magnetic resonance imaging. We describe a versatile methodology to render water dispersibility to [...] Read more.
Stable superparamagnetic iron oxide nanoparticles (SPIONs), which can be easily dispersed in an aqueous medium and exhibit high magnetic relaxivities, are ideal candidates for biomedical applications including contrast agents for magnetic resonance imaging. We describe a versatile methodology to render water dispersibility to SPIONs using tetraethylene glycol (TEG)-based phosphonate ligands, which are easily introduced onto SPIONs by either a ligand exchange process of surface-anchored oleic-acid (OA) molecules or via direct conjugation. Both protocols confer good colloidal stability to SPIONs at different NaCl concentrations. A detailed characterization of functionalized SPIONs suggests that the ligand exchange method leads to nanoparticles with better magnetic properties but higher toxicity and cell death, than the direct conjugation methodology. Full article
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<p>Transmission electron microscopy (TEM) images and histograms of size distribution for water-dispersible SPIONs.</p> Full article ">Figure 2
<p>Hydrodynamic diameters measured from dynamic light scattering (DLS) at various Sodium chloride (NaCl) concentrations for all water-dispersible Super paramagnetic iron oxide nanoparticles (SPIONs).</p> Full article ">Figure 3
<p>Brain endothelial cell viability after 12 and 24 h treatment with water-dispersible SPIONs at various concentrations (μg/mL): (<b>A</b>) SPIONs-OA/PMe; (<b>B</b>) SPIONs-OA/POH; (<b>C</b>) SPIONs-PMe; (<b>D</b>) SPIONs-POH.</p> Full article ">Figure 4
<p>Optical images of bEnd.3 cells treated with 2.5 µg/mL of conjugated SPIONs for 24 h: Control, extreme left; SPIONs-OA/PMe, top middle; SPIONs-PMe, bottom middle; SPIONs-OA/POH, top extreme right; SPIONs-POH, bottom extreme right.</p> Full article ">Scheme 1
<p>Synthetic elaboration of phosphonate-two tetraethylene glycol (TEG)-OH (<b>10</b>) and phosphonate-TEG-Me (<b>14</b>).</p> Full article ">
3806 KiB  
Article
Synthesis of Ball-Like Ag Nanorod Aggregates for Surface-Enhanced Raman Scattering and Catalytic Reduction
by Wenjing Zhang, Yin Cai, Rui Qian, Bo Zhao and Peizhi Zhu
Nanomaterials 2016, 6(6), 99; https://doi.org/10.3390/nano6060099 - 25 May 2016
Cited by 9 | Viewed by 6276
Abstract
In this work, ball-like Ag nanorod aggregates have been synthesized via a simple seed-mediated method. These Ag mesostructures were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV-Vis), and X-ray diffraction (XRD). Adding a certain amount of polyvinyl pyrrolidone [...] Read more.
In this work, ball-like Ag nanorod aggregates have been synthesized via a simple seed-mediated method. These Ag mesostructures were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV-Vis), and X-ray diffraction (XRD). Adding a certain amount of polyvinyl pyrrolidone (PVP) can prolong its coagulation time. These Ag nanorod aggregates exhibit effective SERS effect, evaluated by Rhodamine 6G (R6G) and doxorubicin (DOX) as probe molecules. The limit of detection (LOD) for R6G and DOX are as low as 5 × 10−9 M and 5 × 10−6 M, respectively. Moreover, these Ag nanorod aggregates were found to be potential catalysts for the reduction of 4-nitrophenol (4-NP) in the presence of NaBH4. Full article
(This article belongs to the Special Issue Nanoparticles for Catalysis)
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<p>Scanning electron microscope (SEM) images of the ball-like Ag nanorod aggregates.</p> Full article ">Figure 2
<p>Transmission electron microscopy (TEM) (<b>a</b>) and high resolution TEM (HRTEM) (<b>b</b>) images of the ball-like Ag nanorod aggregates. Inset in (<b>b</b>) is the selected area electron diffraction (SEAD) pattern of Ag nanorod aggregates.</p> Full article ">Figure 3
<p>Ultraviolet-visible spectroscopy (UV-Vis) spectrum of the ball-like Ag nanorod aggregates.</p> Full article ">Figure 4
<p>X-ray diffraction (XRD) pattern of the ball-like Ag nanorod aggregates.</p> Full article ">Figure 5
<p>TEM images of the ball-like Ag nanorod aggregates under different concentrations of AgNO<sub>3</sub>: (<b>a</b>) 5 mM; (<b>b</b>) 10 mM; (<b>c</b>) 15 mM; (<b>d</b>) 20 mM.</p> Full article ">Figure 6
<p>The coagulation condition of Ag nanorod aggregates without adding polyvinyl pyrrolidone (PVP) (left) and with adding PVP (right): (<b>a</b>) 0 min; (<b>b</b>) 10 min; (<b>c</b>) 30 min; (<b>d</b>) 80 min.</p> Full article ">Figure 7
<p>Raman spectra of Rhodamine 6G (R6G) at different concentrations absorbed on Ag nanorod aggregates. Spectra represent the concentrations of R6G being (<b>a</b>) 5 × 10<sup>−6</sup>; (<b>b</b>) 5 × 10<sup>−7</sup>; (<b>c</b>) 5 × 10<sup>−8</sup>; (<b>d</b>) 5 × 10<sup>−9</sup>; (<b>e</b>) 5 × 10<sup>−10</sup> M, respectively.</p> Full article ">Figure 8
<p>Raman spectra of DOX at different concentrations absorbed on Ag nanorod aggregates. Spectra represent the concentrations of DOX being (<b>a</b>) 5 × 10<sup>−4</sup>; (<b>b</b>) 5 × 10<sup>−5</sup>; (<b>c</b>) 5 × 10<sup>−6</sup>; (<b>d</b>) 5 × 10<sup>−7</sup> M, respectively.</p> Full article ">Figure 9
<p>UV-Vis absorption spectra: (<b>a</b>) reduction of 4-NP by NaBH<sub>4</sub> using Ag nanorod aggregates as catalyst; (<b>b</b>) The plot of ln(<span class="html-italic">A</span><sub>t</sub>/<span class="html-italic">A</span><sub>0</sub>) against the reaction time for pseudo-first-order reduction kinetics of 4-NP in the presence of ball-like Ag nanorod aggregates.</p> Full article ">
2535 KiB  
Article
Enhancing the Photocurrent of Top-Cell by Ellipsoidal Silver Nanoparticles: Towards Current-Matched GaInP/GaInAs/Ge Triple-Junction Solar Cells
by Yiming Bai, Lingling Yan, Jun Wang, Lin Su, Zhigang Yin, Nuofu Chen and Yuanyuan Liu
Nanomaterials 2016, 6(6), 98; https://doi.org/10.3390/nano6060098 - 25 May 2016
Cited by 7 | Viewed by 5282
Abstract
A way to increase the photocurrent of top-cell is crucial for current-matched and highly-efficient GaInP/GaInAs/Ge triple-junction solar cells. Herein, we demonstrate that ellipsoidal silver nanoparticles (Ag NPs) with better extinction performance and lower fabrication temperature can enhance the light harvest of GaInP/GaInAs/Ge solar [...] Read more.
A way to increase the photocurrent of top-cell is crucial for current-matched and highly-efficient GaInP/GaInAs/Ge triple-junction solar cells. Herein, we demonstrate that ellipsoidal silver nanoparticles (Ag NPs) with better extinction performance and lower fabrication temperature can enhance the light harvest of GaInP/GaInAs/Ge solar cells compared with that of spherical Ag NPs. In this method, appropriate thermal treatment parameters for Ag NPs without inducing the dopant diffusion of the tunnel-junction plays a decisive role. Our experimental and theoretical results confirm the ellipsoidal Ag NPs annealed at 350 °C show a better extinction performance than the spherical Ag NPs annealed at 400 °C. The photovoltaic conversion efficiency of the device with ellipsoidal Ag NPs reaches 31.02%, with a nearly 5% relative improvement in comparison with the device without Ag NPs (29.54%). This function of plasmonic NPs has the potential to solve the conflict of sufficient light absorption and efficient carrier collection in GaInP top-cell devices. Full article
(This article belongs to the Special Issue Nanostructured Solar Cells)
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<p>(<b>a</b>) Schematic layer structure and (<b>b</b>) cross-sectional view scanning electron microscope (SEM) image of the epitaxial structure of GaInP/GaInAs/Ge triple-junction solar cells (TJSCs).</p> Full article ">Figure 2
<p>Plane-view SEM images of (<b>a</b>) ellipsoidal and (<b>b</b>) spherical Ag NPs.</p> Full article ">Figure 3
<p>(<b>a</b>) Current-voltage (<span class="html-italic">J</span>-<span class="html-italic">V</span>) characteristic curve and (<b>b</b>) external quantum efficiency of the GaInP/GaInAs/Ge device.</p> Full article ">Figure 4
<p>Theoretical (dotted lines) and experimental (solid lines) extinction spectra of spherical Ag NPs with <span class="html-italic">D</span> = 88 nm and ellipsoidal Ag NPs with 2<span class="html-italic">a</span>/2<span class="html-italic">b</span>/2<span class="html-italic">c</span> = 76/94/76 nm.</p> Full article ">Figure 5
<p>External quantum efficiency of GaInP top-cell in TJSCs.</p> Full article ">Figure 6
<p><span class="html-italic">J</span>-<span class="html-italic">V</span> characteristics of GaInP/GaInAs/Ge triple-junction solar cells at one-sun AM 1.5G, 25 °C. The measurement was performed on the 1.1 cm<sup>2</sup> solar cell devices.</p> Full article ">
3335 KiB  
Article
Improving the Photocurrent in Quantum-Dot-Sensitized Solar Cells by Employing Alloy PbxCd1−xS Quantum Dots as Photosensitizers
by Chunze Yuan, Lin Li, Jing Huang, Zhijun Ning, Licheng Sun and Hans Ågren
Nanomaterials 2016, 6(6), 97; https://doi.org/10.3390/nano6060097 - 25 May 2016
Cited by 27 | Viewed by 7225
Abstract
Ternary alloy PbxCd1−xS quantum dots (QDs) were explored as photosensitizers for quantum-dot-sensitized solar cells (QDSCs). Alloy PbxCd1−xS QDs (Pb0.54Cd0.46S, Pb0.31Cd0.69S, and Pb0.24Cd0.76 [...] Read more.
Ternary alloy PbxCd1−xS quantum dots (QDs) were explored as photosensitizers for quantum-dot-sensitized solar cells (QDSCs). Alloy PbxCd1−xS QDs (Pb0.54Cd0.46S, Pb0.31Cd0.69S, and Pb0.24Cd0.76S) were found to substantially improve the photocurrent of the solar cells compared to the single CdS or PbS QDs. Moreover, it was found that the photocurrent increases and the photovoltage decreases when the ratio of Pb in PbxCd1−xS is increased. Without surface protecting layer deposition, the highest short-circuit current density reaches 20 mA/cm2 under simulated AM 1.5 illumination (100 mW/cm2). After an additional CdS coating layer was deposited onto the PbxCd1−xS electrode, the photovoltaic performance further improved, with a photocurrent of 22.6 mA/cm2 and an efficiency of 3.2%. Full article
(This article belongs to the Special Issue Nanostructured Solar Cells)
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<p>Incident photon to current efficiency (IPCE) spectra (<b>a</b>) and current–voltage (I–V) curves (<b>b</b>) of quantum-dot-sensitized solar cells (QDSCs) employing three successive ionic-layer adsorption and reaction (SILAR) cycles of CdS, PbS, and PbCdS-1 as photosensitizers. Inset of (<b>a</b>) is the absorption spectra of three-SILAR-cycle QD-sensitized TiO<sub>2</sub> films. “3C” means three SILAR cycles, and the bare TiO<sub>2</sub> film was used as blank.</p> Full article ">Figure 2
<p>Absorption spectra (<b>a</b>) and Tauc plots (<b>b</b>) of five-SILAR-cycle PbS, PbCdS-1, -2, -3, and CdS-sensitized TiO<sub>2</sub> films. The bare TiO<sub>2</sub> film was used as blank in the absorption measurement. Inset images of (<b>a</b>) show the PbS, PbCdS-1, -2, -3, and CdS electrodes in turn from left to right. The doted tangent lines of the linear region of plots in (<b>b</b>) show the linear fit for the bandgap energy of QDs.</p> Full article ">Figure 3
<p>Cyclic voltammograms (CVs) of five-SILAR-cycle PbS, PbCdS-1, -2, -3, and CdS-sensitized TiO<sub>2</sub> electrode. CVs were measured with the electrolyte of 0.1 M KCl in deionized water (pH 6.9), and the scan rate was 10 mV/s. The arrows indicate the scan direction. The dotted part in the CV figures is to show the onset potentials of the reduction current varied at the different electrodes.</p> Full article ">Figure 4
<p>Dark I–V curves of QDSCs employing five-SILAR-cycle PbS, PbCdS-1, -2, -3, and CdS.</p> Full article ">Figure 5
<p>The photovoltaic parameters of QDSCs employing CdS, PbS, and three Pb<span class="html-italic"><sub>x</sub></span>Cd<sub>1−<span class="html-italic">x</span></sub>S QDs in terms of the number of SILAR cycles. (<b>a</b>) short-circuit current density (<span class="html-italic">J<sub>sc</sub></span>); (<b>b</b>) open-circuit voltage (<span class="html-italic">V<sub>oc</sub></span>); (<b>c</b>) fill factor (<span class="html-italic">FF</span>); (<b>d</b>) efficiency (η).</p> Full article ">Figure 6
<p>(<b>a</b>) IPCE spectra and (<b>b</b>) I–V curves of QDSCs employing PbCdS-1 (seven SILAR cycles), PbCdS-2 (seven SILAR cycles), and PbCdS-3 (nine SILAR cycles).</p> Full article ">Figure 7
<p>I–V curve of QDSC employing a hybrid QDs of PbCdS-1 (seven SILAR cycles) and CdS (three SILAR cycles), where PbCdS-1 was sensitized onto a TiO<sub>2</sub> film, followed by subsequently depositing CdS onto PbCdS-1. Inset: IPCE spectrum of the hybrid QDs compared to the corresponding PbCdS-1 QDs.</p> Full article ">Scheme 1
<p>Schematic diagram of edge energy levels of the conduction band (CB) edge and valence band (VB) edge for TiO<sub>2</sub> and five-SILAR-cycle PbS, CdS, and three kinds of Pb<span class="html-italic"><sub>x</sub></span>Cd<sub>1−<span class="html-italic">x</span></sub>S.</p> Full article ">
4076 KiB  
Article
Structural Changes Induced in Grapevine (Vitis vinifera L.) DNA by Femtosecond IR Laser Pulses: A Surface-Enhanced Raman Spectroscopic Study
by Nicoleta E. Dina, Cristina M. Muntean, Nicolae Leopold, Alexandra Fălămaș, Adela Halmagyi and Ana Coste
Nanomaterials 2016, 6(6), 96; https://doi.org/10.3390/nano6060096 - 25 May 2016
Cited by 11 | Viewed by 5746
Abstract
In this work, surface-enhanced Raman spectra of ten genomic DNAs extracted from leaf tissues of different grapevine (Vitis vinifera L.) varieties, respectively, are analyzed in the wavenumber range 300–1800 cm−1. Furthermore, structural changes induced in grapevine genomic nucleic acids upon [...] Read more.
In this work, surface-enhanced Raman spectra of ten genomic DNAs extracted from leaf tissues of different grapevine (Vitis vinifera L.) varieties, respectively, are analyzed in the wavenumber range 300–1800 cm−1. Furthermore, structural changes induced in grapevine genomic nucleic acids upon femtosecond (170 fs) infrared (IR) laser pulse irradiation (λ = 1100 nm) are discussed in detail for seven genomic DNAs, respectively. Surface-enhanced Raman spectroscopy (SERS) signatures, vibrational band assignments and structural characterization of genomic DNAs are reported for each case. As a general observation, the wavenumber range between 1500 and 1660 cm−1 of the spectra seems to be modified upon laser treatment. This finding could reflect changes in the base-stacking interactions in DNA. Spectral shifts are mainly attributed to purines (dA, dG) and deoxyribose. Pyrimidine residues seem to be less affected by IR femtosecond laser pulse irradiation. Furthermore, changes in the conformational properties of nucleic acid segments are observed after laser treatment. We have found that DNA isolated from Feteasca Neagra grapevine leaf tissues is the most structurally-responsive system to the femtosecond IR laser irradiation process. In addition, using unbiased computational resources by means of principal component analysis (PCA), eight different grapevine varieties were discriminated. Full article
(This article belongs to the Special Issue DNA-Based Nanotechnology)
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<p>Surface-enhanced Raman spectroscopy (SERS) spectra of five selected genomic DNAs isolated from leaves of different grapevine varieties (Feteasca Neagra, Tamaioasa Romaneasca, Gordan, Feteasca Regala, Coarna Neagra), respectively, as labeled in the figure.</p> Full article ">Figure 2
<p>SERS spectra of six selected genomic DNAs isolated from leaves of different grapevine varieties (Ardeleanca, Gordan, Braghina, Carloganca, Francuse, Cramposie), respectively, as labeled in the figure.</p> Full article ">Figure 3
<p>SERS spectra of seven genomic DNAs isolated from leaves of different grapevine varieties (Feteasca Regala, Braghina, Francuse, Carloganca, Feteasca Neagra, Tamaioasa Romaneasca, Ardeleanca), respectively, as labeled in the figure. DNA samples were irradiated with femtosecond infrared (IR) laser pulses (1100 nm, 60 mW average power, 30 min).</p> Full article ">Figure 4
<p>SERS spectra of seven non-irradiated and femtosecond IR laser pulse-treated genomic DNAs extracted from different grapevine varieties, respectively: <b>A</b>, Feteasca Regala; <b>B</b>, Braghina; <b>C</b>, Francuse; <b>D</b>, Carloganca; <b>E</b>, Feteasca Neagra; <b>F</b>, Tamaioasa Romaneasca; <b>G</b>, Ardeleanca.</p> Full article ">Figure 5
<p>Principal component analysis (PCA) scores showing the grouping of the eight sets of SERS spectra of DNAs extracted from different grapevine varieties (Ardeleanca, Coarna Neagra, Feteasca Neagra, Francuse, Gordan, Tamaioasa Romaneasca, Cramposie, Feteasca Regala), respectively.</p> Full article ">Figure 6
<p>First principal component (PC1) loadings showing the marker bands considered as the main contribution (51% explained by the PCA model) in the grouping of the spectral data.</p> Full article ">Figure 7
<p>Second principal component (PC2) loadings showing the marker bands considered as the main contribution (26% explained by the PCA model) in the grouping of the spectral data.</p> Full article ">
4151 KiB  
Article
Ultraviolet Plasmonic Aluminium Nanoparticles for Highly Efficient Light Incoupling on Silicon Solar Cells
by Yinan Zhang, Boyuan Cai and Baohua Jia
Nanomaterials 2016, 6(6), 95; https://doi.org/10.3390/nano6060095 - 24 May 2016
Cited by 45 | Viewed by 7505
Abstract
Plasmonic metal nanoparticles supporting localized surface plasmon resonances have attracted a great deal of interest in boosting the light absorption in solar cells. Among the various plasmonic materials, the aluminium nanoparticles recently have become a rising star due to their unique ultraviolet plasmonic [...] Read more.
Plasmonic metal nanoparticles supporting localized surface plasmon resonances have attracted a great deal of interest in boosting the light absorption in solar cells. Among the various plasmonic materials, the aluminium nanoparticles recently have become a rising star due to their unique ultraviolet plasmonic resonances, low cost, earth-abundance and high compatibility with the complementary metal-oxide semiconductor (CMOS) manufacturing process. Here, we report some key factors that determine the light incoupling of aluminium nanoparticles located on the front side of silicon solar cells. We first numerically study the scattering and absorption properties of the aluminium nanoparticles and the influence of the nanoparticle shape, size, surface coverage and the spacing layer on the light incoupling using the finite difference time domain method. Then, we experimentally integrate 100-nm aluminium nanoparticles on the front side of silicon solar cells with varying silicon nitride thicknesses. This study provides the fundamental insights for designing aluminium nanoparticle-based light trapping on solar cells. Full article
(This article belongs to the Special Issue Nanostructured Solar Cells)
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<p>Schematic diagram of the investigated solar cell structure, consisting of the Al nanoparticles (NPs), the SiN<span class="html-italic"><sub>x</sub></span> spacing layer, and the Si layer with the red spheres representing the metal NPs.</p> Full article ">Figure 2
<p>Calculated normalized scattering (<b>a</b>) and absorption (<b>b</b>) cross sections of the Al NPs with a 100-nm diameter on top of a Si layer, in comparison with Ag and Au NPs.</p> Full article ">Figure 3
<p>(<b>a</b>) Calculated normalized light transmittance of Si solar cells integrated with an array of Al NPs (100-nm diameter and 10% surface coverage), compared with the Si solar cells integrated with Ag and Au NPs. (<b>b</b>) Calculated absorption losses in the NP arrays.</p> Full article ">Figure 4
<p>(<b>a</b>) Calculated transmittance of the Si solar cells with an array of hemispherical and cubic Al NPs (100-nm diameter/width and 10% surface coverage), referenced to that of a bare Si layer. (<b>b</b>) Calculated normalized scattering cross sections of the corresponding Al NPs on top of the Si layer.</p> Full article ">Figure 5
<p>Calculated normalized scattering (<b>a</b>) and absorption (<b>b</b>) cross sections of the Al NPs in the air with 100-nm, 200-nm and 300-nm diameters, respectively.</p> Full article ">Figure 6
<p>Calculated light transmittance into the Si wafer under the configurations of (<b>a</b>) varying diameter at 10% surface coverage and (<b>b</b>) increasing surface coverage from 10% to 70% for a 100-nm particle size.</p> Full article ">Figure 7
<p>(<b>a</b>) Calculated light transmittance spectra of the Si wafer integrated with the Al NP array (100-nm diameter and 10% surface coverage) on top of the 20-nm SiN<span class="html-italic"><sub>x</sub></span>, referenced to that without Al NPs and the bare Si. (<b>b</b>) Calculated integrated light transmittance of the Si wafer with the Al NPs as a function of the SiN<span class="html-italic"><sub>x</sub></span> spacing layer thickness. The inset figures show the relative enhancement.</p> Full article ">Figure 8
<p>Scanning electron images (SEM) of the fabricated Al (<b>a</b>) and Ag (<b>b</b>) NPs (Scale bar: 1 µm). The UV-VIS-NIR spectra of the Al (<b>c</b>) and Ag (<b>d</b>) NPs in deionized water solution.</p> Full article ">Figure 9
<p>(<b>a</b>) Measured reflectance of the Si solar cells integrated with Al and Ag NPs. (<b>b</b>) Measured external quantum efficiency (EQE) enhancement of the solar cells integrated with Al and Ag NPs, relative to that without NPs.</p> Full article ">Figure 10
<p>(<b>a</b>) Measured EQE of the solar cells with the Al NPs on top of a 20-nm SiN<sub>x</sub> spacing layer, compared with that without Al NPs. (<b>b</b>) The corresponding photocurrent density as a function of the SiN<sub>x</sub> layer thickness. The inset figures are the relative enhancement.</p> Full article ">
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