Journal of Nanomaterials The latest articles from Hindawi Publishing Corporation © 2015 , Hindawi Publishing Corporation . All rights reserved. Decoration of Silver Nanoparticles on Multiwalled Carbon Nanotubes: Antibacterial Mechanism and Ultrastructural Analysis Sat, 28 Feb 2015 14:23:55 +0000 Recently, development of carbon nanocomposites composed of carbon nanostructures and metal nanoparticles has attracted much interests because of their large potential for technological applications such as catalyst, sensor, biomedicine, and disinfection. In this work, we established a simple chemistry method to synthesize multiwalled carbon nanotubes (MWCNTs) decorated with silver nanoparticles (Ag-NPs) using a modified photochemical reaction (Tollens process). The formation and interaction of Ag-NPs with functionalized groups on the surface of MWCNTs were analyzed by X-ray diffraction, transmission electron microscopy, Raman spectroscopy, and Fourier-transform infrared spectroscopy. The average size of Ag-NPs on the MWCNTs was approximately ~7 nm with nearly uniform size distribution. Antibacterial effect of Ag-MWCNTs nanocomposites was evaluated against two pathogenic bacteria including Gram-negative Escherichia Coli and Gram-positive Staphylococcus aureus bacteria. Interaction and bactericidal mechanism of Ag-MWCNTs with tested bacteria was studied by adapting the electron microscopy. Analysis on ultrastructural changes of bacterial cells indicates that antibacterial action mechanism of Ag-MWCNTs is physical interaction with cell membrane, the large formation of cell-Ag-MWCNTs aggregates, and faster destructibility of cell membrane and disruption of membrane function, hence resulting in cells death. Ngo Xuan Dinh, Nguyen Van Quy, Tran Quang Huy, and Anh-Tuan Le Copyright © 2015 Ngo Xuan Dinh et al. All rights reserved. Comparison of Precipitated Calcium Carbonate/Polylactic Acid and Halloysite/Polylactic Acid Nanocomposites Sat, 28 Feb 2015 14:23:05 +0000 PLA nanocomposites with stearate coated precipitated calcium carbonate (PCC) and halloysite natural nanotubes (HNT) were prepared by melt extrusion. The crystallization behavior, mechanical properties, thermal dynamical mechanical analysis (DMTA), and the morphology of the PCC/PLA, HNT/PLA, and HNT/PCC/PLA composites were discussed. Compared to halloysite nanotubes, PCC nanoparticles showed a better nucleating effect, which decreased both the glass transition and cold crystallization temperatures. The tensile performance of PLA composites showed that the addition of inorganic nanofillers increased Young’s modulus but decreased tensile strength. More interestingly, PLA composites with PCC particles exhibited an effectively increased elongation at break with respect to pure PLA, while HNT/PLA showed a decreased ultimate deformation of composites. DMTA results indicated that PLA composites had a similar storage modulus at temperatures below the glass transition and the addition of nanofillers into PLA caused to shift to lower temperatures by about 3°C. The morphological analysis of fractures surface of PLA nanocomposites showed good dispersion of nanofillers, formation of microvoids, and larger plastic deformation of the PLA matrix when the PCC particles were added, while a strong aggregation was noticed in composites with HNT nanofillers, which has been attributed to a nonoptimal surface coating. Xuetao Shi, Guangcheng Zhang, Cristina Siligardi, Guido Ori, and Andrea Lazzeri Copyright © 2015 Xuetao Shi et al. All rights reserved. Large-Area Resonance-Tuned Metasurfaces for On-Demand Enhanced Spectroscopy Sat, 28 Feb 2015 12:58:41 +0000 We show an effective procedure for lateral structure tuning in nanoimprint lithography (NIL) that has been developed as a vertical top-down method fabricating large-area nanopatterns. The procedure was applied to optical resonance tuning in stacked complementary (SC) metasurfaces based on silicon-on-insulator (SOI) substrates and was found to realize structure tuning at nm precision using only one mold in the NIL process. The structure tuning enabled us to obtain fine tuning of the optical resonances, offering cost-effective, high-throughput, and high-precision nanofabrication. We also demonstrate that the tuned optical resonances selectively and significantly enhance fluorescence (FL) of dye molecules in a near-infrared range. FL intensity on a SC metasurface was found to be more than 450-fold larger than the FL intensity on flat Au film on base SOI substrate. Masanobu Iwanaga, Bongseok Choi, Hideki T. Miyazaki, Yoshimasa Sugimoto, and Kazuaki Sakoda Copyright © 2015 Masanobu Iwanaga et al. All rights reserved. Ag Nanorod Arrays for SERS: Aspects of Spectral Reproducibility, Surface Contamination, and Spectral Sensitivity Sat, 28 Feb 2015 07:51:12 +0000 Ag nanorod arrays prepared by oblique angle vapor deposition (OAD) represent regular, large area substrates for surface-enhanced Raman scattering (SERS) spectroscopy. We studied uniformity and spectral reproducibility of silver OAD-fabricated substrates (AgOADs) by spectral mapping of methylene blue. The results demonstrate good reproducibility apart from occasional “hot-spot” sites where the intensity is higher. The number of “hot-spots” represents 2%–6% of SERS-active sites of mapping substrate area. We were able to obtain good SERS spectra of testing amino acid tryptophan at 1 × 10−5 M concentration and three different free-base porphyrins down to ∼10−7 M concentration. We found out that keeping the AgOADs in a vacuum chamber overnight prevents the surface from binding any contaminants from the ambient atmosphere, without significant reduction in the SERS enhancement. Such substrates provide stable SERS enhancement even when stored for 1 year after preparation. Martin Šubr, Martin Petr, Vlastimil Peksa, Ondřej Kylián, Jan Hanuš, and Marek Procházka Copyright © 2015 Martin Šubr et al. All rights reserved. Correlation of Defect-Related Optoelectronic Properties in /ZnO Nanostructures with Their Quasi-Fractal Dimensionality Thu, 26 Feb 2015 18:43:36 +0000 Hydrozincite (Zn5(OH)6(CO3)2) is, among others, a popular precursor used to synthesize nanoscale ZnO with complex morphologies. For many existing and potential applications utilizing nanostructures, performance is determined by the surface and subsurface properties. Current understanding of the relationship between the morphology and the defect properties of nanocrystalline ZnO and hydrozincite systems is still incomplete. Specifically, for the latter nanomaterial the structure-property correlations are largely unreported in the literature despite the extensive use of hydrozincite in the synthesis applications. In our work, we addressed this issue by studying precipitated nanostructures of Zn5(OH)6(CO3)2 with varying quasi-fractal dimensionalities containing relatively small amounts of a ZnO phase. Crystal morphology of the samples was accurately controlled by the growth time. We observed a strong correlation between the morphology of the samples and their optoelectronic properties. Our results indicate that a substantial increase of the free surface in the nanocrystal samples generates higher relative concentration of defects, consistent with the model of defect-rich surface and subsurface layers. J. Antonio Paramo, Yuri M. Strzhemechny, Tamio Endo, and Zorica Crnjak Orel Copyright © 2015 J. Antonio Paramo et al. All rights reserved. Preparation and In Vitro Evaluation of a Multifunctional Iron Silicate@Liposome Nanohybrid for pH-Sensitive Doxorubicin Delivery and Photoacoustic Imaging Thu, 26 Feb 2015 08:23:26 +0000 For preventing premature drug release in neutral environment and avoiding them being trapped into the endosomal/lysosomal system, we developed a novel iron silicate@liposome hybrid (ILH) formulation, which can be used as a carrier to transport doxorubicin (DOX) in a pH-sensitive manner and to escape from endosomal/lysosomal trapping through “proton-sponge” effect. The high intensity of photoacoustic signal from in vitro photoacoustic imaging (PAI) experiments suggests that it is a promising candidate for PAI agent, providing the potential for simultaneously bioimaging and cancer-targeting drug delivery. Cytotoxicity of our formulation toward tumor cells was remarkably higher than free DOX (% and %, ). Confocal laser scanning microscopy experiments showed the enhanced transportation and enrichment process of DOX in QSG-7703 cells. Taking together, we developed an easy approach to construct a multifunctional anticancer drug delivery/imaging system with a potency as a PAI agent. The strategy of combining drug carrier and imaging agent is an emerging platform for further construction of nanoparticle and may play a significant role in cancer therapy and diagnosis. Zehua Liu, Shaoheng Tang, Zhiran Xu, Yingjun Wang, Xuan Zhu, Liang-cheng Li, Wanjin Hong, and Xiumin Wang Copyright © 2015 Zehua Liu et al. All rights reserved. The Electrochemical Stability in NaCl Solution of Nanotubes and Nanochannels Elaborated on a New Ti-20Zr-5Ta-2Ag Alloy Thu, 26 Feb 2015 07:33:20 +0000 Nanotubular and nanochannels structures were fabricated via anodizing on a new alloy Ti-20Zr-8Ta-2Ag. A continuous coating of connected tubes/channels can be observed in the SEM micrographs forming tubular structures with diameters in hundreds of nm, as well as smaller tubes, with diameters in tens of nm. In the case of nanochannels structure, the diameters are smaller and wall thicknesses significantly thinner than in nanotubes. Wettability measurements indicate a decrease of contact angles in both cases of nanotubes and nanochannels, but the increase of hydrophilic character is more significant in the case of nanochannels. The Tafel procedure and electrochemical impedance spectroscopy tests performed in NaCl 0.9% solution indicate a better stability for the nanostructured surfaces compared to untreated alloy, the surface with nanochannels offering higher corrosion resistance. Spectral UV-VIS determination has confirmed Ag metallic presence, opening the door for applications not only in tissue engineering but for water splitting and the photoreduction of CO2 as well. Claudiu Constantin Manole, Cristian Pirvu, Andrei Bogdan Stoian, Jose M. Calderon Moreno, Doina Stanciu, and Ioana Demetrescu Copyright © 2015 Claudiu Constantin Manole et al. All rights reserved. PAMAM Dendrimers as Potential Carriers of Gadolinium Complexes of Iminodiacetic Acid Derivatives for Magnetic Resonance Imaging Wed, 25 Feb 2015 11:53:54 +0000 This is the first study describing the utilization of PAMAM dendrimers as delivery vehicles of novel magnetic resonance imaging (MRI) contrast agents. The purpose of this paper was to establish the potential of G4 PAMAM dendrimers as carriers of gadolinium complexes of iminodiacetic acid derivatives and determine imaging properties of synthesized compounds in in vivo studies. Furthermore, we examined the influence of four synthesized complexes on the process of clot formation, stabilization, and lysis and on amidolytic activity of thrombin. Biodistribution studies have shown that the compounds composed of PAMAM G4 dendrimers and gadolinium complexes of iminodiacetic acid derivatives increase signal intensity preferably in liver in range of 59–116% in MRI studies which corresponds with the greatest accumulation of gadolinium after administration of the compounds. Synthesized compounds affect kinetic parameters of the proces of clot formation, its stabilization, and lysis. However, only one synthesized compound at concentration 10-fold higher than potential plasma concentrations contributed to the increase of general parameters such as the overall potential of clot formation and lysis (↑CLAUC) and total time of the process (↑T). Results of described studies provide additional insight into delivery properties of PAMAM dendrimers but simultaneously underscore the necessity for further research. Magdalena Markowicz-Piasecka, Joanna Sikora, Paweł Szymański, Oliwia Kozak, Michał Studniarek, and Elżbieta Mikiciuk-Olasik Copyright © 2015 Magdalena Markowicz-Piasecka et al. All rights reserved. Synthesis and Antibacterial Activity of Antibiotic-Functionalized Graphite Nanofibers Wed, 25 Feb 2015 10:52:34 +0000 Surface functionalization of nanomaterials is an area of current investigation that supports the development of new biomaterials for applications in biology and medicine. Herein we describe the synthesis, characterization, and antibacterial properties of the first examples of antibiotic-labeled graphitic carbon nanofibers (GCNFs) covalently functionalized with aminoglycoside and quinolone antibiotics. Ruthenium tetroxide oxidation of herringbone GCNFs gave higher amounts of surface carboxyl groups than previous methods. These carboxyl groups served as sites of attachment for antibiotics by acyl substitution. Bioassay of these novel, functionalized GCNFs using serial dilution and optical density methods demonstrated that antibiotic-labeled GCNFs possess significant antibacterial activity against Pseudomonas aeruginosa. The activity we observe for aminoglycoside-functionalized GCNFs suggests a membranolytic mechanism of action. Madeline Rotella, Alicia Briegel, John Hull, Anthony Lagalante, and Robert Giuliano Copyright © 2015 Madeline Rotella et al. All rights reserved. Synthesis of LiFePO4/Graphene Nanocomposite and Its Electrochemical Properties as Cathode Material for Li-Ion Batteries Wed, 25 Feb 2015 09:42:24 +0000 LiFePO4/graphene nanocomposite was successfully synthesized by rheological phase method and its electrochemical properties as the cathode materials for lithium ion batteries were measured. As the iron source in the synthesis, FeOOH nanorods anchored on graphene were first synthesized. The FeOOH nanorods precursors and the final LiFePO4/graphene nanocomposite products were characterized by XRD, SEM, and TEM. While the FeOOH precursors were nanorods with 5–10 nm in diameter and 10–50 nm in length, the LiFePO4 were nanoparticles with 20–100 nm in size. Compared with the electrochemical properties of LiFePO4 particles without graphene nanosheets, it is clear that the graphene nanosheets can improve the performances of LiFePO4 as the cathode material for lithium ion batteries. The as-synthesized LiFePO4/graphene nanocomposite showed high capacities and good cyclabilities. When measured at room temperature and at the rate of 0.1C (1C = 170 mA g−1), the composite showed a discharge capacity of 156 mA h g−1 in the first cycle and a capacity retention of 96% after 15 cycles. The improved performances of the composite are believed to be the result of the three-dimensional conducting network formed by the flexible and planar graphene nanosheets. Xiaoling Ma, Gongxuan Chen, Qiong Liu, Guoping Zeng, and Tian Wu Copyright © 2015 Xiaoling Ma et al. All rights reserved. Surface Modification of Porous Titanium with Microarc Oxidation and Its Effects on Osteogenesis Activity In Vitro Tue, 24 Feb 2015 16:25:59 +0000 Microarc oxidation (MAO) is a method about surface treatment that can provide nanoporous pits and thick oxide layers. A kind of porous metal-entangled titanium (Ti) wire material was treated with MAO process, resulting in a homogeneous rough TiO2 layer, which helped facilitate MG-63 cell growth, cell viability, early cell differentiation, and cell mineralization in vitro. In addition, the MAO-treated Ti surfaces could promote the proliferation of MG-63 cells without sacrificing differentiation in vitro, which would benefit de novo bone formation around MAO-treated titanium at the early stage. The transcription levels of the extracellular matrix genes of osterix (OSX), collagen type I (Col I), bone sialoprotein (BSP), alkaline phosphatase (ALP), osteocalcin (OC) and osteopontin (OPN) and their protein expression levels were measured, suggesting that the cocultured cells with MAO titanium maintained the osteoblastic phenotype and that the MAO-treated titanium surface greatly stimulated osteoblast cell proliferation and differentiation compared to the untreated titanium. In conclusion, MAO technique can improve the surface of titanium and can contribute to the osseointegration process. Qi Wang, Mengqi Cheng, Guo He, and Xianlong Zhang Copyright © 2015 Qi Wang et al. All rights reserved. Investigations of the Toxic Effect of Silver Nanoparticles on Mammalian Cell Lines Tue, 24 Feb 2015 08:28:28 +0000 Silver nanoparticles are widely used for many applications. In this study silver nanoparticles have been tested for their toxic effect on fibroblasts (NIH-3T3), on a human lung adenocarcinoma epithelial cell line (A-549), on PC-12-cells, a rat adrenal pheochromocytoma cell line, and on HEP-G2-cells, a human hepatocellular carcinoma cell line. The viability of the cells cultivated with different concentrations of silver was determined by the MTT assay, a photometric method to determine cell metabolism. Dose-response curves were extrapolated and IC50, total lethal concentration (TLC), and no observable adverse effect concentration (NOAEC) values were calculated for each cell line. As another approach, ECIS (electric-cell-substrate-impedance-sensing) an automated method to monitor cellular behavior in real-time was applied to observe cells cultivated with silver nanoparticles. To identify the type of cell death the membrane integrity was analyzed by measurements of the lactate dehydrogenase releases and by determination of the caspase 3/7 activity. To ensure that the cytotoxic effect of silver nanoparticles is not traced back to the presence of Ag+ ions in the suspension, an Ag+ salt (AgNO3) has been examined at the same concentration of Ag+ present in the silver nanoparticle suspension that is assuming that the Ag particles are completely available as Ag+ ions. F. Sambale, S. Wagner, F. Stahl, R. R. Khaydarov, T. Scheper, and D. Bahnemann Copyright © 2015 F. Sambale et al. All rights reserved. Nanomaterials for Energy-Efficient Applications Tue, 24 Feb 2015 07:33:23 +0000 Xiaohu Huang, Guozhong Xing, Yongfeng Li, and Ekaterina Nannen Copyright © 2015 Xiaohu Huang et al. All rights reserved. Potential of Biosynthesized Silver Nanoparticles as Nanocatalyst for Enhanced Degradation of Cellulose by Cellulase Mon, 23 Feb 2015 12:00:18 +0000 Silver nanoparticles (AgNPs) as a result of their excellent optical and electronic properties are promising catalytic materials for various applications. In this study, we demonstrate a novel approach for enhanced degradation of cellulose using biosynthesized AgNPs in an enzyme catalyzed reaction of cellulose hydrolysis by cellulase. AgNPs were synthesized through reduction of silver nitrate by extracts of five medicinal plants (Mentha arvensis var. piperascens, Buddleja officinalis Maximowicz, Epimedium koreanum Nakai, Artemisia messer-schmidtiana Besser, and Magnolia kobus). An increase of around twofold in reducing sugar formation confirmed the catalytic activity of AgNPs as nanocatalyst. The present study suggests that immobilization of the enzyme onto the surface of the AgNPs can be useful strategy for enhanced degradation of cellulose, which can be utilized for diverse industrial applications. Bipinchandra K. Salunke, Shailesh S. Sawant, Tae Koo Kang, Deok Yun Seo, Youngjong Cha, Sun A. Moon, Bassam Alkotaini, Ezhaveni Sathiyamoorthi, and Beom Soo Kim Copyright © 2015 Bipinchandra K. Salunke et al. All rights reserved. Functionalization of Cellulose Fibres with Oxygen Plasma and ZnO Nanoparticles for Achieving UV Protective Properties Mon, 23 Feb 2015 08:55:42 +0000 Low-pressure oxygen plasma created by an electrodeless radiofrequency (RF) discharge was applied to modify the properties of cellulosic fibrous polymer (cotton) in order to improve adsorption properties towards zinc oxide (ZnO) nanoparticles and to achieve excellent ultraviolet (UV) protective properties of cotton fabric. The chemical and physical surface modifications of plasma-treated cotton fabric were examined by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The mechanical properties of plasma-treated samples were evaluated, measuring strength and elongation of the fabrics. The quantity of zinc on the ZnO-functionalized cotton samples was determined using inductively coupled plasma mass spectrometry (ICP-MS) and the effectiveness of plasma treatment for UV protective properties of cotton fabrics was evaluated using UV-VIS spectrometry, measuring the UV protection factor (UPF). The results indicated that longer plasma treatment times cause higher concentration of oxygen functional groups on the surface of fibres and higher surface roughness of fibres. These two conditions are crucial in increasing the content of ZnO nanoparticles on the fibres, providing excellent UV protective properties of treated cotton, with UPF factor up to 65.93. Katja Jazbec, Martin Šala, Miran Mozetič, Alenka Vesel, and Marija Gorjanc Copyright © 2015 Katja Jazbec et al. All rights reserved. The Preparation of a Highly Stretchable Cellulose Nanowhisker Nanocomposite Hydrogel Mon, 23 Feb 2015 08:30:18 +0000 Molecules that associate to form cross-links by hydrophobic association are designed and synthesised. Hydrogels, based on cellulose nanowhiskers (CNWs), acrylamide (AM), and stearyl methacrylate (C18), were synthesised by micellar copolymerisation, using ammonium peroxydisulfate as an initiator. CNWs composite hydrogels were characterised by Fourier transform infrared spectroscopy (FTIR) and their morphologies were investigated by scanning electron microscope (SEM). The system shows the original extensibility up to about 2500%: the tensile strength and compressive strength have maximum values of 1.338 MPa and 2.835 MPa, respectively. Besides excellent mechanical properties, CNWs composite hydrogels also have the ability to self-heal and remould: this is mainly attributed to the dissociation and reassociation of the associated micelles. In contrast to conventional cellulose hydrogels, these systems, when broken or cut, can be simply repaired by bringing together fractured surfaces to self-heal at room temperature. Jiufang Duan, Jianxin Jiang, Jianzhang Li, Liujun Liu, Yiqiang Li, and Chao Guan Copyright © 2015 Jiufang Duan et al. All rights reserved. Synthesis, Characterization, Properties, and Applications of Nanosized Ferroelectric, Ferromagnetic, or Multiferroic Materials Mon, 23 Feb 2015 08:11:51 +0000 Debasis Dhak, Seungbum Hong, Soma Das, and Prasanta Dhak Copyright © 2015 Debasis Dhak et al. All rights reserved. Effects of Two Different Cellulose Nanofiber Types on Properties of Poly(vinyl alcohol) Composite Films Sun, 22 Feb 2015 11:18:26 +0000 This work concerns a study on the effects of fiber types and content of cellulose nanofiber on mechanical, thermal, and optical properties polyvinyl alcohol (PVA) composites. Two different types of cellulose nanofibers, which are nanofibrillated cellulose (NFC) and bacterial cellulose (BC), were prepared under various mechanical treatment times and then incorporated into the PVA prior to the fabrication of composite films. It was found that tensile modulus of the PVA film increased with nanofibers content at the expense of its percentage elongation value. DSC thermograms indicate that percentage crystallinity of PVA increased after adding 2–4 wt% of the fibers. This contributed to the better mechanical properties of the composites. Tensile toughness values of the PVA/BC nanocomposite films were also superior to those of the PVA/NFC system containing the same fiber loading. SEM images of the composite films reveal that tensile fractured surface of PVA/BC experienced more ductile deformation than the PVA/NFC analogue. The above discrepancies were discussed in the light of differences between the two types of fibers in terms of diameter and their intrinsic properties. Lastly, percentage total visible light transmittance values of the PVA composite films were greater than 90%, regardless of the fiber type and content. Kitti Yuwawech, Jatuphorn Wootthikanokkhan, and Supachok Tanpichai Copyright © 2015 Kitti Yuwawech et al. All rights reserved. Characterization of Multiferroic Domain Structures in Multiferroic Oxides Sun, 22 Feb 2015 06:52:49 +0000 Multiferroic oxides have been received much attention due to that these materials exhibit multiple ferroic order parameters (e.g., electric polarization in ferroelectrics, magnetization in ferromagnetics, or spontaneous strain in ferroelastics) simultaneously in the same phase in a certain temperature range, which offer an exciting way of coupling between the ferroic order parameters. Thus, this provides a possibility for constructing new type of multifunctional devices. The multiferroic domain structures in these materials are considered to be an important factor to improve the efficiency and performance of future multiferroic devices. Therefore, the domain structures in multiferroic oxides are widely investigated. Recent developments in domain characterization techniques, particularly the aberration-corrected transmission electron microscopy (TEM), have enabled us to determine the domain structures at subangstrom scale, and the recent development of in situ TEM techniques allows ones to study the dynamic behaviors of multiferroic domains under applied fields or stress while the atomic structure is imaged directly. This paper provides a review of recent advances on the characterization of multiferroic domain structures in multiferroic oxides, which have been achieved by the notable advancement of aberration-corrected TEM. Lizhi Liang, Heng Wu, Lei Li, and Xinhua Zhu Copyright © 2015 Lizhi Liang et al. All rights reserved. Ferroelectric and Dielectric Properties of ZnFe2O4-Pb(ZrTi)O3 Multiferroic Nanocomposites Thu, 19 Feb 2015 13:05:16 +0000 Magnetoelectric composites of zinc ferrite and soft lead zirconate titanate (PZT) having formula 0.5 ZnFe2O4-0.5 PZT were synthesized by sol-gel technique. X-ray diffraction analysis was carried out to confirm the coexistence of individual phase. TEM micrographs were taken to confirm the formation of nanosized powders and SEM micrographs were taken to study the morphology of the sintered pellets. Dielectric and P-E hysteresis loops were recorded, respectively, to confirm the ferroelectric properties of the composites. Shrabanee Sen, Sk. Md. Mursalin, and M. Maharajan Copyright © 2015 Shrabanee Sen et al. All rights reserved. Growth of BiFeO3 Microcylinders under a Hydrothermal Condition Thu, 19 Feb 2015 12:05:24 +0000 BiFeO3 microcylinders were synthesized via a hydrothermal condition. SEM observation reveals that with increasing the hydrothermal reaction time from 6 to 15 h, the microcylinders grow from ~0.7 to ~4.1 μm in height, whereas their diameter remains to be 3.7-3.8 μm with a minor change. The microcylinders are mainly made up of sphere-like grains of 100–150 nm in size. A possible growth mechanism of the BiFeO3 microcylinders is proposed. The photocatalytic activity of the as-prepared BiFeO3 samples was evaluated by the degradation of acid orange 7 under simulated sunlight irradiation, revealing that they possess an appreciable photocatalytic activity. Magnetic hysteresis loop measurement shows that the BiFeO3 microcylinders exhibit a typical antiferromagnetic behavior at room temperature. L. J. Di, H. Yang, T. Xian, J. Y. Ma, H. M. Zhang, J. L. Jiang, Z. Q. Wei, and W. J. Feng Copyright © 2015 L. J. Di et al. All rights reserved. Synthesis and Cytotoxicity of POSS Modified Single Walled Carbon Nanotubes Thu, 19 Feb 2015 12:02:13 +0000 Single walled carbon nanotubes (SWNTs) decorated with polyhedral oligomeric silsesquioxane (POSS) were synthesized via the amide linkages between the acid treated SWNTs and amine-functionalized POSS. The successful modification of SWNTs with POSS was confirmed by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and UV-Vis spectra. The resulting SWNTs-POSS can be dispersed in both water and organic solutions. The biocompatibility and cytotoxicity of the SWNTs and SWNTs-POSS were evaluated by CCK-8 viability assays, which indicated that SWNTs-POSS exhibit very extremely low toxicity. The low toxicity of the POSS modified SWNTs leads to more opportunities for using carbon nanotubes in biomedical fields. Yuhua Xue and Hao Chen Copyright © 2015 Yuhua Xue and Hao Chen. All rights reserved. Synthesis of Monodispersed Gold Nanoparticles with Exceptional Colloidal Stability with Grafted Polyethylene Glycol-g-polyvinyl Alcohol Thu, 19 Feb 2015 11:15:19 +0000 Herein, we report the synthesis of spherical gold nanoparticles with tunable core size (23–79 nm) in the presence of polyethylene glycol-g-polyvinyl alcohol (PEG-g-PVA) grafted copolymer as a reducing, capping, and stabilizing agent in a one-step protocol. The resulted PEG-g-PVA-capped gold nanoparticles are monodispersed with an exceptional colloidal stability against salt addition, repeated centrifugation, and extensive dialysis. The effect of various synthesis parameters and the kinetic/mechanism of the nanoparticle formation are discussed. Alaaldin M. Alkilany, Alaa I. Bani Yaseen, and Mohammed H. Kailani Copyright © 2015 Alaaldin M. Alkilany et al. All rights reserved. Ultra-Sensitive Colorimetric Plasmonic Sensing and Microfluidics for Biofluid Diagnostics Using Nanohole Array Wed, 18 Feb 2015 16:00:13 +0000 Colorimetric techniques provide a useful approach for sensing application because of their low cost, use of inexpensive equipment, requirement of fewer signal transduction hardware, and, above all, their simple-to-understand results. Colorimetric sensor can be used for both qualitative analyte identification as well as quantitative analysis for many application areas such as clinical diagnosis, food quality control, and environmental monitoring. A gap exists between high-end, accurate, and expensive laboratory equipment and low-cost qualitative point-of-care testing tools. Here, we present a label-free plasmonic-based colorimetric sensor fabricated on a transparent plastic substrate consisting of about one billion nanocups in an array with a subwavelength opening and decorated with metal nanoparticles on the side walls, to bridge that gap. The fabrication techniques of the plasmonic sensor, integration to portable microfluidic devices for lab on chip applications, demonstration of highly sensitive refractive-index sensing, DNA hybridization detection, and protein-protein interaction will be reviewed. Further, we anticipate that the colorimetric sensor can be applied to point-of-care diagnostics by utilizing proper surface functionalization techniques, which seems to be one of the current limiting factors. Finally, the future outlook for the colorimetric plasmonic sensors is discussed. Abid Ameen, Manas Ranjan Gartia, Austin Hsiao, Te-Wei Chang, Zhida Xu, and Gang Logan Liu Copyright © 2015 Abid Ameen et al. All rights reserved. Improved Visible Light Photocatalytic Activity for TiO2 Nanomaterials by Codoping with Zinc and Sulfur Wed, 18 Feb 2015 09:13:12 +0000 S/Zn codoped TiO2 nanomaterials were synthesized by a sol-gel method. X-ray diffraction, UV-vis diffuse reflectance spectroscopy, transmission electron microscopy, photoluminescence spectroscopy, and X-ray photoelectron spectroscopy were used to characterize the morphology, structure, and optical properties of the prepared samples. The introduction of Zn and S resulted in significant red shift of absorption edge for TiO2-based nanomaterials. The photocatalytic activity was evaluated by degrading reactive brilliant red X-3B solution under simulated sunlight irradiation. The results showed S/Zn codoped TiO2 exhibited higher photocatalytic activity than pure TiO2 and commercial P25, due to the photosynergistic effect of obvious visible light absorption, efficient separation of photoinduced charge carriers, and large surface area. Moreover, the content of Zn and S in the composites played important roles in photocatalytic activity of TiO2-based nanomaterials. Qianzhi Xu, Xiuying Wang, Xiaoli Dong, Chun Ma, Xiufang Zhang, and Hongchao Ma Copyright © 2015 Qianzhi Xu et al. All rights reserved. Direct Preparation and Characterization of Copper Pentacyanonitrosylferrate Nanoparticles Mon, 16 Feb 2015 07:28:55 +0000 The present work describes the preparation of nanoparticles of copper pentacyanonitrosyl complexes starting from the compound sodium nitroprusside. Copper pentacyanonitrosylferrate (NCuNP) nanoparticles were successfully synthesized by using deionized water and formamide as solvent. The material was characterized by Fourier-transforming infrared spectroscopy (FT-IR), X-ray diffraction (XRD), ultraviolet-visible (UV-Vis) spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and cyclic voltammetry (CV). The results revealed that the electronic spectra of NCuNP exhibited a broad intervalence charge transfer band at 685 nm. An XRD peak broadening pattern of the NCuNP was verified, indicating a particle decrease when formamide is used. The particle size of NCuNP is estimated to be 80 nm. The cyclic voltammogram of the modified graphite paste electrode with NCuNP showed two redox pairs with formal potentials  V and  V ( mV s−1; KCl 1.0 M), attributed to the redox process and [(CN)5NO]/[(CN)5NO], respectively. The graphite paste electrode with NCuNP presents electrocatalytic response for Sulfite determination. D. R. Do Carmo, M. M. Souza, U. O. Bicalho, V. S. Dos Santos, J. P. Souza, and D. R. Silvestrini Copyright © 2015 D. R. Do Carmo et al. All rights reserved. Extracellular Biosynthesis of Copper and Copper Oxide Nanoparticles by Stereum hirsutum, a Native White-Rot Fungus from Chilean Forests Sun, 15 Feb 2015 14:36:49 +0000 The white-rot fungus Stereum hirsutum was studied to evaluate its applicability for use in the biosynthesis of copper/copper oxide nanoparticles under different pH conditions and in the presence of three different copper salts (CuCl2, CuSO4, and Cu(NO3)2). The nanoparticle formation was evaluated by UV-visible spectroscopy, electron microscopy (TEM), X-ray diffraction analysis (XRD), and Fourier transforms infrared spectroscopy (FTIR). The nanoparticles biosynthesis in presence of all copper salts demonstrated higher formation with 5 mM CuCl2 under alkaline conditions. TEM analysis confirmed that the nanoparticles were mainly spherical (5 to 20 nm). The presence of amine groups attached to nanoparticles was confirmed by FTIR, which suggests that extracellular protein of fungus is responsible for the formation of the nanoparticles. Therefore, the white-rot fungus S. hirsutum was found to exhibit potential for use in the synthesis of copper/copper oxide nanoparticles. R. Cuevas, N. Durán, M. C. Diez, G. R. Tortella, and O. Rubilar Copyright © 2015 R. Cuevas et al. All rights reserved. The Effect of Charge at the Surface of Silver Nanoparticles on Antimicrobial Activity against Gram-Positive and Gram-Negative Bacteria: A Preliminary Study Sun, 15 Feb 2015 14:21:10 +0000 The bactericidal efficiency of various positively and negatively charged silver nanoparticles has been extensively evaluated in literature, but there is no report on efficacy of neutrally charged silver nanoparticles. The goal of this study is to evaluate the role of electrical charge at the surface of silver nanoparticles on antibacterial activity against a panel of microorganisms. Three different silver nanoparticles were synthesized by different methods, providing three different electrical surface charges (positive, neutral, and negative). The antibacterial activity of these nanoparticles was tested against gram-positive (i.e., Staphylococcus aureus, Streptococcus mutans, and Streptococcus pyogenes) and gram-negative (i.e., Escherichia coli and Proteus vulgaris) bacteria. Well diffusion and micro-dilution tests were used to evaluate the bactericidal activity of the nanoparticles. According to the obtained results, the positively-charged silver nanoparticles showed the highest bactericidal activity against all microorganisms tested. The negatively charged silver nanoparticles had the least and the neutral nanoparticles had intermediate antibacterial activity. The most resistant bacteria were Proteus vulgaris. We found that the surface charge of the silver nanoparticles was a significant factor affecting bactericidal activity on these surfaces. Although the positively charged nanoparticles showed the highest level of effectiveness against the organisms tested, the neutrally charged particles were also potent against most bacterial species. Abbas Abbaszadegan, Yasamin Ghahramani, Ahmad Gholami, Bahram Hemmateenejad, Samira Dorostkar, Mohammadreza Nabavizadeh, and Hashem Sharghi Copyright © 2015 Abbas Abbaszadegan et al. All rights reserved. Mechanical Properties of High-Viscosity Glass Ionomer Cement and Nanoparticle Glass Carbomer Sun, 15 Feb 2015 09:35:13 +0000 Introduction. The lack of evidence regarding the best available material for restoring occlusal-proximal cavities in primary teeth leads to the development of new restorative material, with nanoparticles, in order to enhance mechanical properties, resulting in increased restoration longevity. Aim. To evaluate the Knoop hardness and bond strength of nanoparticles material glass carbomer cement (CAR) and high-viscosity glass ionomer cement (GIC) in sound and caries-affected dentin. Methods. Forty bovine incisors were selected and assigned into four groups (): SGIC, sound dentin and GIC; SCAR, sound dentin and CAR; CGIC, caries-affected dentin and GIC; and CCAR, caries-affected dentin and CAR. All groups were submitted to microshear bond strength (MPa). Knoop hardness was also performed. Bond strength values were subjected to two-way ANOVA and Tukey test. Knoop hardness data were subjected to one-way ANOVA. Results. GIC presented higher Knoop hardness () and bond strength () than CAR. Also, both materials showed better performance in sound than in caries-affected substrates (). The interaction between factors was not statistically different (). Conclusion. Despite nanoparticles, CAR shows inferior performance as compared to GIC for the two properties tested in vitro. Moreover, sound dentin results in better bonding performance of both restorative materials evaluated. Isabel Cristina Olegário, Anna Paula Vieira Ferreira Prado Malagrana, Sabrina Sun Ha Kim, Daniela Hesse, Tamara Kerber Tedesco, Ana Flávia Bissoto Calvo, Lucila Basto Camargo, and Daniela Prócida Raggio Copyright © 2015 Isabel Cristina Olegário et al. All rights reserved. Surface-Initiated Atom Transfer Radical Polymerization of Magnetite Nanoparticles with Statistical Poly(tert-butyl acrylate)-poly(poly(ethylene glycol) methyl ether methacrylate) Copolymers Sun, 15 Feb 2015 08:46:45 +0000 This work presented the surface modification of magnetite nanoparticle (MNP) with poly[(t-butyl acrylate)-stat-(poly(ethylene glycol) methyl ether methacrylate)] copolymers (P[(t-BA)-stat-PEGMA]) via a surface-initiated “grafting from” atom transfer radical polymerization (ATRP). Loading molar ratio of t-BA to PEGMA was systematically varied (100 : 0, 75 : 25, 50 : 50, and 25 : 75, resp.) such that the degree of hydrophilicity of the copolymers, affecting the particle dispersibility in water, can be fine-tuned. The reaction progress in each step of the synthesis was monitored via Fourier transform infrared spectroscopy (FTIR). The studies in the reaction kinetics indicated that PEGMA had higher reactivity than that of t-BA in the copolymerizations. Gel permeation chromatography (GPC) indicated that the molecular weights of the copolymers increased with the increase of the monomer conversion. Transmission electron microscopy (TEM) revealed that the particles were spherical with averaged size of 8.1 nm in diameter. Dispersibility of the particles in water was apparently improved when the copolymers were coated as compared to P(t-BA) homopolymer coating. The percentages of MNP and the copolymer in the composites were determined via thermogravimetric analysis (TGA) and their magnetic properties were investigated via vibrating sample magnetometry (VSM). Patcharin Kanhakeaw, Boonjira Rutnakornpituk, Uthai Wichai, and Metha Rutnakornpituk Copyright © 2015 Patcharin Kanhakeaw et al. All rights reserved.