WorldWideScience

Sample records for nafion coated silver

  1. Nanostructured silver and platinum modified carbon fiber microelectrodes coated with nafion for H2O2 determination

    Directory of Open Access Journals (Sweden)

    Vladimir Halouzka

    2010-12-01

    Full Text Available Carbon fiber microelectrodes equipped with nanostructured metals(platinum and silver and covered with a Nafion layer constitutesensitive H2O2 sensors. Metallic layers on carbon fibers wereprepared by surfactant assisted electrodeposition. In the case ofsilver, the procedure leads to coating which is composed of porous,partially aggregated and crystalline deposits containing silvernanoparticles. The electrodeposition of platinum leads to carbonfiber decorated with clusters of platinum nanoparticles. Aftercoating the electrodes with protective and antiinterference barriermade of Nafion, the sensing properties of the preparedmicroelectrodes towards hydrogen peroxide are investigated.

  2. Silver Nafion for Thermogalvanic Applications

    Science.gov (United States)

    Chang, William; Popere, Bhooshan; Evans, Chris; Russ, Boris; Segalman, Rachel

    2015-03-01

    Thermogalvanics convert a temperature gradient, typically from waste heat, into electrical power using a reversible electrochemical reaction. The conversion efficiency in thermogalvanics, like with thermoelectrics, are governed by the Seebeck coefficient, the carrier conductivity and the thermal conductivity of the material. We demonstrate that the material systems silver Nafion and silver poly-styrenesulfonate are air-stable, water processable materials that demonstrate extremely high Seebeck coefficients and moderate carrier conductivities. These power factors, when coupled with the low thermal conductivities inherent in polymers, results in materials with excellent thermogalvanic figure of merits. We show the dependence of these three material properties to material composition and processing. In this talk, we show how the Seebeck coefficient in silver Nafion and silver polystyrene-sulfonate are opposite in sign, allowing construction of a thermogalvanic device. With these ion conductors, we hope to open up a flexible pathway to waste heat recovery using materials typically studied for electrochemical applications.

  3. Nafion/polypyrrole and Nafion/DMSO Organic Coatings for Magnesium Protection

    Institute of Scientific and Technical Information of China (English)

    Renguo SONG; Xiaohua ZHENG; Carsten Blawert; Wolfgang Dietzel

    2007-01-01

    Nafion/polypyrrole and Nafion/Dimethysulfoxid (DMSO) organic coatings were prepared on the surface of pure magnesium by simple immersion and heat treatment. The morphologies and corrosion resistance of the organic coatings were investigated by using optical microscopy and electrochemical corrosion testing, respectively. It is shown that Nafion/polypyrrole organic coatings resulted in the corrosion resistance of magnesium decreasing;while Nafion/DMSO organic coatings can effectively improve the corrosion resistance of magnesium. Also,the corrosion resistance increased with the thickness of the Nafion/DMSO organic coating increased.

  4. Corrosion Protection of AM50 Magnesium Alloy by Nafion/DMSO Organic Coatings

    Institute of Scientific and Technical Information of China (English)

    SONG Renguo; ZHENG Xiaohua; BAI Shuju; BLAWERT Carsten; DIETZEL Wolfgang

    2008-01-01

    The effectiveness of the corrosion protection of Nafion/Dimethysulfoxid (DMSO) organic coatings for AM50 magnesium alloy prepared by simple immersion and heat treatment was investigated. Its corrosion resistance and morphologies of the Nafion/DMSO organic coatings were studied by electrochemical corrosion testing and optical microscopy. The results show that Nafion/DMSO organic coatings can improve the corrosion resistance of AM50 magnesium alloy effectively. Also, the corrosion resistance increases with the surface density of the organic coatings.

  5. Nafion-CNT coated carbon-fiber microelectrodes for enhanced detection of adenosine.

    Science.gov (United States)

    Ross, Ashley E; Venton, B Jill

    2012-07-07

    Adenosine is a neuromodulator that regulates neurotransmission. Adenosine can be monitored using fast-scan cyclic voltammetry at carbon-fiber microelectrodes and ATP is a possible interferent in vivo because the electroactive moiety, adenine, is the same for both molecules. In this study, we investigated carbon-fiber microelectrodes coated with Nafion and carbon nanotubes (CNTs) to enhance the sensitivity of adenosine and decrease interference by ATP. Electrodes coated in 0.05 mg mL(-1) CNTs in Nafion had a 4.2 ± 0.2 fold increase in current for adenosine, twice as large as for Nafion alone. Nafion-CNT electrodes were 6 times more sensitive to adenosine than ATP. The Nafion-CNT coating did not slow the temporal response of the electrode. Comparing different purine bases shows that the presence of an amine group enhances sensitivity and that purines with carbonyl groups, such as guanine and hypoxanthine, do not have as great an enhancement after Nafion-CNT coating. The ribose group provides additional sensitivity enhancement for adenosine over adenine. The Nafion-CNT modified electrodes exhibited significantly more current for adenosine than ATP in brain slices. Therefore, Nafion-CNT modified electrodes are useful for sensitive, selective detection of adenosine in biological samples.

  6. Ordered mesoporous carbon/Nafion as a versatile and selective solid-phase microextraction coating.

    Science.gov (United States)

    Zeng, Jingbin; Zhao, Cuiying; Chen, Jingjing; Subhan, Fazle; Luo, Liwen; Yu, Jianfeng; Cui, Bingwen; Xing, Wei; Chen, Xi; Yan, Zifeng

    2014-10-24

    In this study, ordered mesoporous carbon (OMC) with large surface area (1019m(2)g(-1)), uniform mesoporous structure (pore size distribution centering at 4.2nm) and large pore volume (1.46cm(3)g(-1)) was synthesized using 2D hexagonally mesoporous silica MSU-H as the hard template and sucrose as the carbon precursor. The as-synthesized OMC was immobilized onto a stainless steel wire using Nafion as a binder to prepare an OMC/Nafion solid-phase microextraction (SPME) coating. The extraction characteristics of the OMC/Nafion coating were extensively investigated using a wide range of analytes including non-polar (light petroleum and benzene homologues) and polar compounds (amines and phenols). The OMC/Nafion coating exhibited much better extraction efficiency towards all selected analytes than that of a multi-walled carbon nanotubes/Nafion coating with similar length and thickness, which is ascribed to its high surface area, well-ordered mesoporous structure and large pore volume. When the OMC/Nafion coating was used to extract a mixture containing various kinds of analytes, it possessed excellent extraction selectivity towards aromatic non-polar compounds. In addition, the feasibility of the OMC/Nafion coating for application in electrochemically enhanced SPME was demonstrated using protonated amines as model analytes. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Electrochemical Impedance Characterization of Nafion-Coated Carbon Film Resistor Electrodes for Electroanalysis

    OpenAIRE

    Gouveia-Caridade, Carla; Brett, Christopher M. A.

    2005-01-01

    Carbon film disk electrodes with Nafion coatings have been characterized by electrochemical impedance spectroscopy (EIS) with a view to a better understanding of their advantages and limitations in electroanalysis, particularly in anodic stripping voltammetry of metal ions. After initial examination by cyclic voltammetry, spectra were recorded over the full potential range in acetate buffer solution at the bare electrodes, electrodes electrochemically pretreated in acid solution, and Nafion-c...

  8. Molecular Composite Coatings on Nafion Using Layer-by-Layer Self-Assembly.

    Science.gov (United States)

    Lefaux, Christophe J; Kim, Byoung-Suhk; Venkat, Narayanan; Mather, Patrick T

    2015-05-20

    Controlled growth of nanometer-scale multilayered coatings of negatively charged sulfonated poly(benzobisimidazole) (SPBI), complexed with positively charged poly(2-vinylpyridine) (P2VP) on quartz, and Nafion membrane as substrates has been explored. Both polymers, SPBI and P2VP, possess a net charge in methanol as a result of the dissolution of SPBI by complexation with triethylamine (TEA) and the protonation of P2VP with HCl, respectively, and thereby can form a multilayered molecular composite of alternating anionic SPBI and cationic P2VP via an electrostatic layer-by-layer (LbL) self-assembly. UV-vis absorption spectrophotometry was used to monitor the buildup and growth rate of such SPBI/P2VP multilayer films. Atomic force microscopy (AFM) was used to determine the roughness and thickness of the resulting SPBI/P2VP multilayers. As a result, it was found that a steady-state linear growth regime for the LbL self-assembled SPBI/P2VP multilayer films and coatings onto quartz and Nafion membranes was observed after completion of the first few deposition cycles, indicating the successful formation of the SPBI/P2VP multilayered assembly in methanol solutions. In addition, the SPBI/P2VP multilayer films in the perpendicular direction (flat view) demonstrated isotropic orientation distribution on the Nafion membrane, while the SPBI/P2VP multilayer films examined by X-ray scattering in the parallel direction (edge view) revealed anisotropic orientation, the combined observations indicating confinement of SPBI rods to the plane of the coating. We further found that the SPBI/P2VP multilayer coated Nafion possesses good thermal stability, as indicated by isothermal gravimetric analysis at 310 °C, and it was further observed that SPBI/P2VP multilayer coatings using the LbL self-assembly technique on Nafion membrane significantly increased the membrane stiffness, despite the small coating thickness employed.

  9. Chronically Implanted, Nafion-Coated Ag/AgCl Reference Electrodes for Neurochemical Applications.

    Science.gov (United States)

    Hashemi, Parastoo; Walsh, Paul L; Guillot, Thomas S; Gras-Najjar, Julie; Takmakov, Pavel; Crews, Fulton T; Wightman, R Mark

    2011-11-16

    Fast-scan cyclic voltammetry (FSCV) at carbon fiber microelectrodes can be used to measure behaviorally correlated dopamine changes in the extracellular fluid of the brain of freely moving rats. These experiments employ a chronically implanted Ag/AgCl reference electrode. When dopamine measurements are taken 4 days after implantation, there is often a potential shift, typically greater than +0.2 V, in the anodic and cathodic peaks in the cyclic voltammogram for dopamine. In this work, we optimized a method to coat sintered Ag/AgCl reference electrodes with the perfluorinated polymer, Nafion, to prevent this shift. We find that we can stabilize reference electrodes for up to 28 days. Immunohistochemistry of the tissue around the implant site shows extensive glial encapsulation around both bare and Nafion-coated devices. However, the lesion around bare electrodes has a rough texture implying that these cells are strongly adsorbed onto the bare reference electrode, while the lesion around a Nafion-coated electrode shows that cells are more intact implying that they adsorb less strongly. EDS and SEM analysis of the surface of the electrodes confirms this by visualizing a heavy build up of plaques, organic in nature, only on bare electrodes. Impedance spectroscopy indicates no difference between the impedance of bare and Nafion-coated Ag/AgCl electrodes, indicating that glial encapsulation does not lead to an increase in uncompensated resistance between the working and reference electrodes. The electrochemical shift therefore must be due to the unique chemical microenvironment around the reference electrode that alters the chloride equilibrium, a process that the Nafion coating prevents.

  10. Preparation of Nafion-sulfonated clay nanocomposite membrane for direct menthol fuel cells via a film coating process

    Science.gov (United States)

    Kim, Tae Kyoung; Kang, Myeongsoon; Choi, Yeong Suk; Kim, Hae Kyung; Lee, Wonmok; Chang, Hyuk; Seung, Doyoung

    Nafion sulfonated clay nanocomposite membranes were successfully produced via a film coating process using a pilot coating machine. For producing the composite membranes, we optimized the solvent ratio of N-methyl-2-pyrrolidinone (NMP) to N, N‧-dimethylacetamide (DMAc), the amount of sulfonated montmorillonite (S-MMT) in composite membranes and the overall concentration of composite dispersions. Based on the optimized viscosity and composition, the composite dispersions were coated on a poly(ethylene terephthalate) (PET) substrate film. The distance between a metering roll and a PET film and the ratio of metering roll speed versus coating roll speed of the pilot coating machine were varied to control membrane thickness. The film coated composite membrane exhibited enhanced properties in the swelling behavior against MeOH solution, ion conductivity and MeOH permeability, compared to the cast Nafion composite membrane due to the higher dispersion state of S-MMT in Nafion matrix and the uniform distribution of small-size ion clusters. These properties influenced a cell performance test of a direct methanol fuel cell (DMFC), showing the film coated composite membrane had a higher power density than that of Nafion 115. The power density was also related with the higher selectivity of the composite membrane than Nafion 115.

  11. Acceleration Techniques for Recombination of Gases in Electrolysis Microactuators with Nafion®-Coated Electrocatalyst

    Science.gov (United States)

    Sheybani, Roya; Meng, Ellis

    2015-01-01

    Recombination of electrolysis gases (oxidation of hydrogen and reduction of oxygen) is an important factor in operation efficiency of devices employing electrolysis such as actuators and also unitized regenerative fuel cells. Several methods of improving recombination speed and repeatability were developed for application to electrolysis microactuators with Nafion®-coated catalytic electrodes. Decreasing the electrolysis chamber volume increased the speed, consistency, and repeatability of the gas recombination rate. To further improve recombination performance, methods to increase the catalyst surface area, hydrophobicity, and availability were developed and evaluated. Of these, including in the electrolyte pyrolyzed-Nafion®-coated Pt segments contained in the actuator chamber accelerated recombination by increasing the catalyst surface area and decreasing the gas transport diffusion path. This approach also reduced variability in recombination encountered under varying actuator orientation (resulting in differing catalyst/gas bubble proximity) and increased the rate of recombination by 2.3 times across all actuator orientations. Repeatability of complete recombination for different generated gas volumes was studied through cycling. PMID:26251561

  12. Corrigendum to "Preparation of Nafion-sulfonated clay nanocomposite membrane for direct menthol fuel cells via a film coating process" [J. Power Sources 165 (2007) 1-2

    Science.gov (United States)

    Kim, Tae Kyoung; Kang, Myeongsoon; Choi, Yeong Suk; Kim, Hae Kyung; Lee, Wonmok; Chang, Hyuk; Seung, Doyoung

    The author regrets that the above paper was printed with an error in the title. The correct title reads: "Preparation of Nafion-sulfonated clay nanocomposite membrane for direct methanol fuel cells via a film coating process".

  13. Preventing the dissolution of lithium polysulfides in lithium-sulfur cells by using Nafion-coated cathodes.

    Science.gov (United States)

    Oh, Soo Jung; Lee, Jun Kyu; Yoon, Woo Young

    2014-09-01

    The principal drawback of lithium-sulfur batteries is the dissolution of long-chain lithium polysulfides into the electrolyte, which limits cycling performance. To overcome this problem, we focused on the development of a novel cathode as well as anode material and designed Nafion-coated NiCrAl/S as a cathode and lithium powder as an anode. Nafion-coated NiCrAl/S cathode was synthesized using a two-step dip-coating technique. The lithium-powder anode was used instead of a lithium-foil anode to prohibit dendrite growth and to improve on the electrochemical behaviors. The cells showed an initial discharge capacity of about 900 mA g(-1) and a final discharge capacity of 772 mA g(-1) after 100 cycles at 0.1 C-rate. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) demonstrate that using the Nafion-coated NiCrAl/S cathode can suppress the dissolution of long-chain lithium polysulfides.

  14. Retarding of electrochemical oxidation of formate on the platinum anode by a coat of Nafion membrane

    Science.gov (United States)

    Zhang, Rui; Lv, Weixin; Li, Guanghua; Mezaal, Mohammed Adnan; Li, Xiaojing; Lei, Lixu

    2014-12-01

    It has been found that the faradaic efficiency is decreasing with the electrolysis time for electrochemical reduction of CO2 to formate on a Sn cathode with a Pt anode in an undivided electrolytic cell, because the oxidation of formed formate takes place on the Pt anode, which also limits seriously the highest concentration of formate in the system. Here, we report that a coat of Nafion membrane on the Pt anode can retard the oxidation of formate: even if the concentration of the formate in the electrolyte reaches to 0.12 mol L-1, the faradaic efficiency still maintains above 61.3%; in contrast, the oxidation reaction of the formate on the naked Pt electrode is very fast, when the concentration of the formate in the electrolyte reaches to 0.023 mol L-1, the faradaic efficiency decreases to 35.3%. This is very important because the separation of formic acid could not be economical when its concentration is not high enough, and it is also costly if the depleted solution allows too less of its concentration because the solution has to be reused in the electrochemical process.

  15. Biological coating of paper using silver nanoparticles.

    Science.gov (United States)

    Ghorbani, Hamid Reza

    2014-12-01

    The capacity of Ag nanoparticles to destroy various micro-organisms makes it one of the most powerful antimicrobial agents, an attractive feature against antibiotic resistant bacteria. Here, a simple method to develop coating of colloidal silver on paper using a biological method is presented. The coated paper was studied by scanning electron microscopy, X-ray diffraction technique and atomic absorption spectroscopy. The antibacterial activity of the coated paper against Escherichia coli and Staphylococcus aureus was measured by agar diffusion method. This study shows the potential use of the coated paper as a food antimicrobial packing material for longer shelf life.

  16. Substrate independent silver nanoparticle based antibacterial coatings.

    Science.gov (United States)

    Taheri, Shima; Cavallaro, Alex; Christo, Susan N; Smith, Louise E; Majewski, Peter; Barton, Mary; Hayball, John D; Vasilev, Krasimir

    2014-05-01

    Infections arising from bacterial adhesion and colonization on medical device surfaces are a significant healthcare problem. Silver based antibacterial coatings have attracted a great deal of attention as a potential solution. This paper reports on the development of a silver nanoparticles based antibacterial surface that can be applied to any type of material surface. The silver nanoparticles were surface engineered with a monolayer of 2-mercaptosuccinic acid, which facilitates the immobilization of the nanoparticles to the solid surface, and also reduces the rate of oxidation of the nanoparticles, extending the lifetime of the coatings. The coatings had excellent antibacterial efficacy against three clinically significant pathogenic bacteria i.e. Staphylococcus epidermidis, Staphylococcus aureus and Pseudomonas aeruginosa. Studies with primary human fibroblast cells showed that the coatings had no cytotoxicity in vitro. Innate immune studies in cultures of primary macrophages demonstrated that the coatings do not significantly alter the level of expression of pro-inflammatory cytokines or the adhesion and viability of these cells. Collectively, these coatings have an optimal combination of properties that make them attractive for deposition on medical device surfaces such as wound dressings, catheters and implants. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Characterization of antibacterial silver coated yarns.

    Science.gov (United States)

    Pollini, M; Russo, M; Licciulli, A; Sannino, A; Maffezzoli, A

    2009-11-01

    Surface treatments of textile fibers and fabrics significantly increase their performances for specific biomedical applications. Nowadays, silver is the most used antibacterial agent with a number of advantages. Among them, it is worth to note the high degree of biocompatibility, an excellent resistance to sterilization conditions, antibacterial properties with respect to different bacteria associated with a long-term of antibacterial efficiency. However, there are only a few antibacterial fibres available, mainly synthetic with high production cost and limited effectiveness. Cotton yarns with antimicrobial properties are most suitable for wound healing applications and other medical treatments thanks to their excellent moisture absorbance while synthetic based fibres are most suitable for industrial applications such as automotive tapestry and air filters. The silver-coated fibers were developed applying an innovative and low cost silver deposition technique for natural and synthetic fibers or yarns. The structure and morphology of the silver nanoclusters on the fibers was observed by scanning electron microscopy (SEM), atomic force microscopy analysis (AFM) and XRD analysis, and quantitatively confirmed by thermogravimetric analysis (TGA) measurements. Good silver coating stability has been confirmed performing several industrial washing. Antimicrobial tests with Escherichia coli were performed.

  18. Glass frits coated with silver nanoparticles for silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yingfen, E-mail: lyf350857423@163.com; Gan, Weiping; Zhou, Jian; Li, Biyuan

    2015-06-30

    Graphical abstract: - Highlights: • Silver-coated glass frits for solar cells were prepared by electroless plating. • Gum Arabic was used as the activating agent of glass frits. • Silver-coated glass frits can improve the photovoltaic performances of solar cells. - Abstract: Glass frits coated with silver nanoparticles were prepared by electroless plating. Gum Arabic (GA) was used as the activating agent of glass frits without the assistance of stannous chloride or palladium chloride. The silver-coated glass frits prepared with different GA dosages were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and thermogravimetric analysis (TGA). The characterization results indicated that silver-coated glass frits had the structures of both glass and silver. Spherical silver nanoparticles were distributed on the glass frits evenly. The density and particle size of silver nanoparticles on the glass frits can be controlled by adjusting the GA dosage. The silver-coated glass frits were applied to silver pastes to act as both the densification promoter and silver crystallite formation aid in the silver electrodes. The prepared silver-coated glass frits can improve the photovoltaic performances of solar cells.

  19. Wettability of Nafion and Nafion/Vulcan carbon composite films.

    Science.gov (United States)

    Li, Xiaoan; Feng, Fangxia; Zhang, Ke; Ye, Siyu; Kwok, Daniel Y; Birss, Viola

    2012-04-24

    The wettability of the Pt/carbon/Nafion catalyst layer in proton exchange membrane fuel cells is critical to their performance and durability, especially the cathode, as water is needed for the transport of protons to the active sites and is also involved in deleterious Pt nanoparticle dissolution and carbon corrosion. Therefore, the focus of this work has been on the first-time use of the water droplet impacting method to determine the wettability of 100% Nafion films, as a benchmark, and then of Vulcan carbon (VC)/Nafion composite films, both deposited by spin-coating in the Pt-free state. Pure Nafion films, shown by SEM analysis to have a nanochanneled structure, are initially hydrophobic but become hydrophilic as the water droplet spreads, likely due to reorientation of the sulfonic acid groups toward water. The wettability of VC/Nafion composite films depends significantly on the VC/Nafion mass ratios, even though Nafion is believed to be preferentially oriented (sulfonate groups toward VC) in all cases. At low VC contents, a significant water droplet contact angle hysteresis is seen, similar to pure Nafion films, while at higher VC contents (>30%), the films become hydrophobic, also exhibiting superhydrophobicity, with surface roughness playing a significant role. At >80% VC, the surfaces become wettable again as there is insufficient Nafion loading present to fully cover the carbon surface, allowing the calculation of the Nafion:carbon ratio required for a full coverage of carbon by Nafion.

  20. Silver modified platinum surface/H{sup +} conducting Nafion membrane for cathodic reduction of nitrate ions

    Energy Technology Data Exchange (ETDEWEB)

    Hasnat, M.A., E-mail: mahtazim@yahoo.com [Department of Chemistry, Graduate School of Physical Sciences, Shahajalal University of Science and Technology, Sylhet 3114 (Bangladesh); School of Chemical Sciences, Universiti Sains Malaysia, 11800 Minden, Penang (Malaysia); Ahamad, N.; Nizam Uddin, S.M. [Department of Chemistry, Graduate School of Physical Sciences, Shahajalal University of Science and Technology, Sylhet 3114 (Bangladesh); Mohamed, Norita [School of Chemical Sciences, Universiti Sains Malaysia, 11800 Minden, Penang (Malaysia)

    2012-01-15

    Electrocatalytic reduction of NO{sub 3}{sup -} was performed at an Ag modified Pt electrodes supported on a H{sup +} conducting Nafion-117 polymer electrolyte. The cyclic voltammetric and electrolysis experiments showed that the reduction process was a two-electron transfer reaction. The conversion of nitrate to nitrite follows first order kinetics. Controlled potential electrolysis experiments revealed that the highest reduction rate (k{sub 1}; 95.1 Multiplication-Sign 10{sup -3} min{sup -1}) could be obtained at -1.3 V versus Ag/AgCl (std. KCl) reference electrode. Meanwhile, substantial nitrate removal (ca. 89%) could be attained by a flow system when the flow rate is as low as 0.1 ml min{sup -1}. The Ag particles on the Pt film were a in polycrystalline state having roughness value of 0.45 {mu}m, which was reduced to 0.30 {mu}m after 270 min of undergoing electrolysis.

  1. Effects of recording media composition on the responses of Nafion-coated carbon fiber microelectrodes measured using high-speed chronoamperometry.

    Science.gov (United States)

    Gerhardt, G A; Hoffman, A F

    2001-08-15

    The present study concerns methodological issues of electrochemical recordings using Nafion-coated 30 microm diameter single carbon fiber microelectrodes for high-speed chronoamperometric measurements of biogenic amines. First, the single carbon fiber microelectrodes were coated with Nafion and dried at 85 vs. 200 degrees C and their recording properties were determined. Second, the effects of shifts in solution pH, ionic strength, changes in recording solution levels of Ca(2+) or Mg(2+) and temperature on the recording characteristics and sensitivity of Nafion-coated high temperature dried (200 degrees C) single carbon fiber microelectrodes for measures of dopamine were studied. These studies showed that the high temperature drying of the Nafion produced a microelectrode with better recording properties: higher selectivity for cations versus anions, increased differences between the reduction and oxidation current ratios for the identification of dopamine versus serotonin, and more rapid response times. In addition, these studies demonstrated that the chronoamperometric recordings were insensitive to small changes in pH and divalent cations such as Ca(2+) or Mg(2+). However, increases in ionic strength decreased the sensitivity of the microelectrodes, while increases in temperature produced increases in the sensitivity of the microelectrodes for biogenic amines. These data support that Nafion-coated high temperature (200 degrees C) dried microelectrodes have enhanced recording properties as compared to microelectrodes, which are coated with Nafion and dried at 85 degrees C. In addition, high-speed chronoamperometric recordings of biogenic amines are not affected by solution changes in divalent cations (Ca(2+) or Mg(2+)).

  2. Nafion-Modified PEDOT:PSS as a Transparent Hole-Transporting Layer for High-Performance Crystalline-Si/Organic Heterojunction Solar Cells with Improved Light Soaking Stability.

    Science.gov (United States)

    Hossain, Jaker; Liu, Qiming; Miura, Takuya; Kasahara, Koji; Harada, Daisuke; Ishikawa, Ryo; Ueno, Keiji; Shirai, Hajime

    2016-11-23

    We demonstrate the chemistry of amphiphilic perfluorosulfonic copolymer Nafion-coated conductive poly(3,4-ethyelenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and its effect on the photovoltaic performance of PEDOT:PSS/crystalline Si (c-Si) heterojunction solar cells. The highly hydrophilic sulfonate group of insulating, chemically stable Nafion interacts with PSS in PEDOT:PSS, which reduce the Coulombic interaction between PEDOT and PSS. The highly hydrophobic fluorocarbon backbone of Nafion favorably interacts with hydrophobic PEDOT of PEDOT:PSS. These factors give rise to the extension of π-conjugation of PEDOT chains. Silver paste used as a top grid electrode diffused into the Nafion layer and contacted with underneath Nafion-modified PEDOT:PSS layer. As a consequent, solution-processed Nafion-coated PEDOT:PSS/c-Si heterojunction solar cells exhibited a higher power conversion efficiency of 14.0% with better stability for light soaking rather than that of the pristine PEDOT:PSS/c-Si device by adjusting the layer thickness of Nafion. These findings originate from the chemical stability of hydrophobic fluorocarbon backbone of Nafion, diffusivity of silver paste into Nafion and contact with PEDOT:PSS, and Nafion as an antireflection layer.

  3. A nafion coated capacitive humidity sensor on a flexible PET substrate

    KAUST Repository

    Sapsanis, Christos

    2017-03-07

    This paper reports a simple and low-cost technique for fabricating low-power capacitive humidity sensors without the use of a cleanroom environment. A maskless laser engraving system was utilized to fabricate two different gold electrode structures, interdigitated electrodes and Hilbert\\'s fifth-order fractal. The capacitive structures were implemented on a flexible PET substrate. The usage of Nafion, a well-known polymer for its hydrophilic properties as a sensing film, was attempted on the PET and outperformed the current efforts in flexible substrates. Its humidity sensing properties were evaluated in an automated gas setup with a relative humidity (RH %) ranging from 15% to 95 %.

  4. Influence of injected silver content on synthesis of silver coated nickel particles by DC thermal plasma

    Science.gov (United States)

    Park, Si Taek; Kim, Tae-Hee; Park, Dong-Wha

    2016-06-01

    Silver nanoparticle-coated spherical nickel particles were prepared from a mixture of micro-sized silver and nickel as raw materials by DC thermal plasma treatment. The mixture of micro-sized silver and nickel powders was injected into the high-temperature region of an argon thermal plasma jet. Although the silver, with its very high thermal conductivity and relatively low boiling point, was thoroughly evaporated by this process, nickel was not evaporated perfectly because of its comparatively low thermal conductivity and high boiling point. The rough nickel powder was spheroidized as it melted. Finally, silver evaporated by the thermal plasma quickly condensed into nanoparticles on the surfaces of the micro-sized spherical nickel particles, aided by the sharp temperature gradient of the thermal plasma jet. With varying the ratios of silver to nickel feedstock from 1:10 to 5:1, the products synthesized in each condition were examined by XRD, XPS, FE-SEM, and FE-TEM. More silver nanoparticles were attached on the nickel by increasing the injected feedstock to 9.8 at% silver. Meanwhile, a decrease of silver in the products was observed when larger amounts of silver were introduced to the thermal plasma jet. The exposed silver components decreased with greater proportions of silver feedstock because of the metal's dendritic structure and the formation of silver-coated silver particles.

  5. UV-Shifted Durable Silver Coating for Astronomical Mirrors

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, N.L.; Wolfe, J.

    2000-06-01

    Silver has the highest reflectance of all of the metals, but it tarnishes in the presence of sulfides, chlorides, and oxides in the atmosphere. Also, the silver reflectance is very low at wavelengths below 400 nm making aluminum more desirable mirror coating for the UV region. They have found a way to prevent silver tarnishing by sandwiching the silver layer between two thin layers of NiCrN{sub x}, and to extend the metal's high reflectance down to 200 nm by depositing the (thin) Ag layer on top of Al. Thus, the uv is transmitted through the thin Ag layer below 400 nm wavelength, and is reflected from the Al layer underneath. This UV-shifted durable coating provides a valuable alternative to the aluminum coating for telescope mirror coatings where high throughput and durability are important considerations. The throughput for a telescope with, say, six reflections from silver coatings is (0.97){sup 6} = 83% compared to (0.92){sup 6} = 60% for aluminum coatings, or 28% less. The use of silver coatings allows more photons to be collected by primary mirror. Aluminum also has a reflectance dip at 850 nm caused by inter-band transitions which is eliminated by placing the thin Ag layer on top. This paper describes a non-tarnishing silver coating having high reflectance down into the UV region. The average specular reflectance is 70%-97% in the near-UV, 95%-99% in the visible region, and {ge} 99% in the infrared region covering the total wavelength range 200 nm to 10,000 nm. Figure 1 compares the reflectance of the UVHR-LLNL silver coating to bare silver and aluminum over-coated with magnesium fluoride over the wavelength range 300 nm to 2000 nm.

  6. In vivo electrochemical monitoring of serotonin in spinal dorsal horn with Nafion-coated multi-carbon fiber electrodes.

    Science.gov (United States)

    Rivot, J P; Cespuglio, R; Puig, S; Jouvet, M; Besson, J M

    1995-09-01

    Biosensors sensitive for in vivo monitoring of serotonin (5-HT) in the CNS by differential normal pulse voltammetry were constructed by coating treated multicarbon fiber electrodes (mCFEs) with Nafion (N-mCFE). In vitro sensitivities of mCFE and N-mCFE were compared in solutions ranging from 5 nM to 20 microM of uric acid (UA), 5-hydroxyindoleacetic acid (5-HIAA), and 5-HT. The mCFEs were three to seven times less sensitive for 5-HIAA or UA than for 5-HT. Nafion treatment dramatically decreased sensitivity for 5-HIAA and UA of N-mCFEs (approximately 10(3) times), whereas it remained in the nanomolar range for 5-HT. In vivo, in the dorsal horn of the lumbar spinal cord of anesthetized rats, the monoamine oxidase inhibitor clorgyline (10 mg/kg i.p.) produced a reduction (55 +/- 3% at 180 min) of peak 3 of oxidation current (characteristic of 5-hydroxyindoles) monitored with mCFEs, but with N-mCFEs (in this latter case the peak was termed 3N) peak 3N increased to 135 +/- 5% at 180 min. The 5-HT release-inducer p-chloroamphetamine (PCA; 6 mg/kg i.p.) induced a slight (12 +/- 3% at 150 min) decrease in peak 3 measured with mCFEs, whereas with N-mCFEs PCA induced a rapid increase of peak 3N (137 +/- 6% at 90 min). The xanthine oxidase inhibitor allopurinol (10 mg/kg i.p.) produced a decrease (30 +/- 3% at 180 min) in peak 3 (mCFEs), but peak 3N (N-mCFEs) was not affected (106% at 180 min). After pretreatment with allopurinol, PCA also produced an increase (135 +/- 6% at 90 min) in peak 3N.(ABSTRACT TRUNCATED AT 250 WORDS)

  7. High extraction efficiency for polar aromatic compounds in natural water samples using multiwalled carbon nanotubes/Nafion solid-phase microextraction coating.

    Science.gov (United States)

    Chen, Wenfeng; Zeng, Jingbin; Chen, Jinmei; Huang, Xiaoli; Jiang, Yaqi; Wang, Yiru; Chen, Xi

    2009-12-25

    A novel solid-phase microextraction (SPME) fiber coated with multiwalled carbon nanotubes (MWCNTs)/Nafion was developed and applied for the extraction of polar aromatic compounds (PACs) in natural water samples. The characteristics and the application of this fiber were investigated. Electron microscope photographs indicated that the MWCNTs/Nafion coating with average thickness of 12.5microm was homogeneous and porous. The MWCNTs/Nafion coated fiber exhibited higher extraction efficiency towards polar aromatic compounds compared to an 85microm commercial PA fiber. SPME experimental conditions, such as fiber coating, extraction time, stirring rate, desorption temperature and desorption time, were optimized in order to improve the extraction efficiency. The calibration curves were linear from 0.01 to 10microgmL(-1) for five PACs studied except p-nitroaniline (from 0.005 to 10microgmL(-1)) and m-cresol (from 0.001 to 10microgmL(-1)), and detection limits were within the range of 0.03-0.57ngmL(-1). Single fiber and fiber-to-fiber reproducibility were less than 7.5 (n=7) and 10.0% (n=5), respectively. The recovery of the PACs spiked in natural water samples at 1microgmL(-1) ranged from 83.3 to 106.0%.

  8. Surface-modified Nafion membranes with mesoporous SiO 2 layers via a facile dip-coating approach for direct methanol fuel cells

    Science.gov (United States)

    Lin, Yuhan; Li, Haidong; Liu, Changpeng; Xing, Wei; Ji, Xiangling

    In this study, Nafion ® 117 membrane is surface-modified with mesoporous silica layers through in situ surfactant-templated sol-gel reaction. The reaction makes use of tetraethyl orthosilicate (TEOS) under acidic condition via dip-coating technique on both sides. Scanning electron microscopy (SEM), Fourier transformation infrared (FTIR), and thermogravimetric analysis (TGA) are employed to characterize the resultant membranes. Proton conductivity and methanol permeability of the membranes are also studied. It is determined that the aging time, along with the number of the silicon dioxide (SiO 2) layer, influence both proton conductivity and methanol permeability. Specifically, double-side modified membrane with 5 min interval of the second layer (S (5)) exhibits optimal properties on the combined criterion of conductivity and permeability. However, the application of mesoporous silica layer in modifying commercial Nafion membranes through dip-coating is proven to be a facile route in improving the said criteria simultaneously.

  9. High Reflectivity, Broad-Band Silver Coating Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Silver coatings for optics greater than 2-meters in diameter are sought by NASA for future space telescope systems. In the Phase I research, Surface Optics...

  10. Silver-coated megaprostheses: review of the literature.

    Science.gov (United States)

    Schmidt-Braekling, Tom; Streitbuerger, Arne; Gosheger, Georg; Boettner, Friedrich; Nottrott, Markus; Ahrens, Helmut; Dieckmann, Ralf; Guder, Wiebke; Andreou, Dimosthenis; Hauschild, Gregor; Moellenbeck, Burkhard; Waldstein, Wenzel; Hardes, Jendrik

    2017-03-06

    Periprosthetic infection remains one of the most serious complications following megaendoprostheses. Despite a large number of preventive measures that have been introduced in recent years, it has not been possible to further reduce the rate of periprosthetic infection. With regard to metallic modification of implants, silver in particular has been regarded as highly promising, since silver particles combine a high degree of antimicrobial activity with a low level of human toxicity. This review provides an overview of the history of the use of silver as an antimicrobial agent, its mechanism of action, and its clinical application in the field of megaendoprosthetics. The benefits of silver-coated prostheses could not be confirmed until now. However, a large number of retrospective studies suggest that the rate of periprosthetic infections could be reduced by using silver-coated megaprostheses.

  11. Silver nanoparticles-coated glass frits for silicon solar cells

    Science.gov (United States)

    Li, Yingfen; Gan, Weiping; Li, Biyuan

    2016-04-01

    Silver nanoparticles-coated glass frit composite powders for silicon solar cells were prepared by electroless plating. Silver colloids were used as the activating agent of glass frits. The products were characterized by X-ray diffraction, scanning electron microscopy, and differential scanning calorimetry. The characterization results indicated that silver nanoparticles with the melting temperature of 838 °C were uniformly deposited on glass frit surface. The particle size of silver nanoparticles could be controlled by adjusting the [Ag(NH3)2]NO3 concentration. The as-prepared composite powders were applied in the front side metallization of silicon solar cells. Compared with those based on pure glass frits, the solar cells containing the composite powders had the denser silver electrodes and the better silver-silicon ohmic contacts. Furthermore, the photovoltaic performances of solar cells were improved after the electroless plating.

  12. Preparation of sintered silver nanosheets by coating technique using silver carbamate complex

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Hee-Yong; Cha, Jae-Ryung; Gong, Myoung-Seon, E-mail: msgong@dankook.ac.kr

    2015-03-01

    This study describes a coating technique approach for large-scale preparation of sintered silver nanosheets whose lateral dimensions were controlled in the thickness range of 50–65 nm. These procedures involved coating water-soluble poly (vinyl alcohol) (PVA) and silver 2-ethylhexylcarbamate (Ag-EHC), as well as thermal reduction of a silver precursor by heating at 150 °C, followed by dissolving away the PVA layer with alcoholic water. When the silver carbamate layer on the PVA layer was heated to 150 °C, the silver carbamate layer was thermally reduced and directed to grow into uniform sintered nanosheets with aspect ratios as high as 1000. The multi-stacked PVA/Ag structures and sintered silver nanosheets were confirmed by scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction. Measurements of the conductive property at room temperature indicated that these nanosheets were electrically continuous with a resistivity of approximately 7.3 × 10{sup −6} Ω cm. - Highlights: • A coating technique is used to make sintered Ag nanosheets. • PVA and silver carbamate act as a separation layer and a silver precursor. • The Ag nanosheets have thickness width 50–60 nm and width up to hundred μm. • The Ag nanosheets showed a resistivity of ca. 7.3 × 10{sup −6} Ω cm.

  13. Antibacterial silver nanocluster/silica composite coatings on stainless steel

    Science.gov (United States)

    Ferraris, M.; Perero, S.; Ferraris, S.; Miola, M.; Vernè, E.; Skoglund, S.; Blomberg, E.; Odnevall Wallinder, I.

    2017-02-01

    A coating made of silver nanocluster/silica composites has been deposited, via a radio frequency (RF) co-sputtering technique, for the first time onto stainless steel (AISI 304L) with the aim to improve its antibacterial properties. Different thermal treatments after coating deposition have been applied in order to optimize the coating adhesion, cohesion and its antibacterial properties. Its applicability has been investigated at realistic conditions in a cheese production plant. The physico-chemical characteristics of the coatings have been analyzed by means of different bulk and surface analytical techniques. Field emission scanning electron microscopy (FESEM), X-ray Photoelectron Spectroscopy (XPS), contact angle measurements and atomic force microscopy (AFM) were employed to assess coating morphology, composition, surface roughness, wetting properties, size and local distribution of the nanoparticles within the coating. Tape tests were used to determine the adhesion/cohesion properties of the coating. The amount and time-dependence of released silver in solutions of acetic acid, artificial water, artificial tap water and artificial milk were determined by means of Atomic Absorption Spectroscopy (AAS). The antibacterial effect of the coating was evaluated at different experimental conditions using a standard bacterial strain of Staphylococcus aureus in compliance with National Committee for Clinical Laboratory Standards (NCCLS) and AATCC 147 standards. The Ahearn test was performed to measure the adhesion of bacteria to the coated stainless steel surface compared with a control surface. The antibacterial coating retained its antibacterial activity after thermal treatment up to 450 °C and after soaking in common cleaning products for stainless steel surfaces used for e.g. food applications. The antibacterial capacity of the coating remained at high levels for 1-5 days, and showed a good capacity to reduce the adhesion of bacteria up to 30 days. Only a few

  14. SERS-applicable silver nanoisland film grown under protective coating

    Science.gov (United States)

    Reduto, I.; Chervinskii, S.; Matikainen, A.; Baklanov, A.; Kamenskii, A.; Lipovskii, A.

    2014-10-01

    We have used recently developed out-diffusion technique of growing silver nanoisland films on glass surface to grow silver nanoislands under TiO2 layer deposited on the glass. After covering the surface of silver ion-exchanged glasses with TiO2 film using atomic layer deposition technique and subsequent thermal processing of the samples in hydrogen their optical absorption spectra demonstrate the absorption peak corresponding to surface plasmon resonance in grown silver nanoislands. The spectral position of the peak is shifted relatively to the peak observed in the spectra of the nanoisland film grown on the surface of ion exchanged and annealed glass samples without dielectric cover. The applicability of the silver nanoislands grown under several nm thick protective TiO2 coating in surface-enhanced Raman scattering spectroscopy is demonstrated.

  15. Patchy silica-coated silver nanowires as SERS substrates

    Energy Technology Data Exchange (ETDEWEB)

    Hunyadi Murph, Simona E.; Murphy, Catherine J.

    2013-05-08

    We report a class of core-shell nanomaterials that can be used as efficient surface-enhancement Raman scattering (SERS) substrates. The core consists of silver nanowires, prepared through a chemical reduction process, that are used to capture 4- mercaptobenzoic acid (4-MBA), a model analyte. The shell was prepared through a modified Stöber method and consists of patchy or full silica coats. The formation of silica coats was monitored via transmission electron microscopy, UV-visible spectroscopy and phase-analysis light scattering for measuring effective surface charge. Surprisingly, the patchy silica coated silver nanowires are better SERS substrate than silver nanowires; nanomolar concentration of 4-MBA can be detected. In addition, “nano-matryoshka” configurations were used to quantitate/explore the effect of the electromagnetic field at the tips of the nanowire (“hot spots”) in the Raman scattering experiment.

  16. Antimicrobial titanium/silver PVD coatings on titanium

    OpenAIRE

    Thull Roger; Glückermann Susanne K; Ewald Andrea; Gbureck Uwe

    2006-01-01

    Abstract Background Biofilm formation and deep infection of endoprostheses is a recurrent complication in implant surgery. Post-operative infections may be overcome by adjusting antimicrobial properties of the implant surface prior to implantation. In this work we described the development of an antimicrobial titanium/silver hard coating via the physical vapor deposition (PVD) process. Methods Coatings with a thickness of approximately 2 μm were deposited on titanium surfaces by simultaneous ...

  17. Osteoblast adhesion to functionally graded hydroxyapatite coatings doped with silver.

    Science.gov (United States)

    Sandukas, Stefan; Yamamoto, Akiko; Rabiei, Afsaneh

    2011-06-15

    Silver-doped functionally graded hydroxyapatite (Ag-FGHA) coatings have been prepared on glass and titanium substrates by ion beam assisted deposition (IBAD) method with in situ heat treatment, and the biological response and dissolution properties of the coatings have been examined. Three Ag-FGHA coatings with different percentages of silver (1, 3, and 6.6 wt % Ag) were compared with pure FGHA (without Ag) as a control. MC 3T3-E1 murine osteoblast cells were cultured on FGHA and Ag-FGHA coating surfaces, and the number of adhered cells after 1, 4, and 7 days was counted. Micromanipulation of live single cells was performed to quantitatively compare cell affinity among the four coating compositions. Results showed that FGHA-Ag1 coating (with 1 wt % Ag) had the highest number of adhered cells after each incubation period, as well as the highest cell affinity after 24-h incubation. Surface profilometry was performed to determine surface roughness average (R(a) ) of coating surfaces before and after immersion in high-purity water, showing that all surfaces initially had roughness averages below 200 nm, while after immersion, roughness average of FGHA-Ag1 surface was significantly increased (R(a) = 404 +/- 100.8 nm), attributed to the highest rate of dissolution. Release rate of Ag+ ions in solution was measured, showing release rates of silver ions for all Ag-doped coatings were initially high and then gradually decreased to a minimum over time, which is the expected dissolution of functionally graded coatings. It is concluded that FGHA-Ag1 coating promoted the highest degree of osteoblast adhesion because of optimal dissolution rate and nontoxic Ag percentage.

  18. Antibacterial PVD coatings doped with silver by ion implantation

    Science.gov (United States)

    Osés, J.; Palacio, J. F.; Kulkarni, S.; Medrano, A.; García, J. A.; Rodríguez, R.

    2014-08-01

    The antibacterial effect of certain metal ions, like silver, has been exploited since antiquity. Obviously, the ways to employ the biocide activity of this element have evolved throughout time and it is currently used in a wide range of clinical applications. The work presented here reports the results of an investigation focused on combining the protective properties of PVD coatings with the biocide property of silver, applied by ion implantation. For this purpose, chromium nitride layers were doped with silver implanted at two different doses (5 × 1016 and 1 × 1017 ion/cm2) at 100 keV of energy and perpendicular incidence. Full characterization of the coatings was performed to determine its topographical and mechanical properties. The concentration profile of Ag was analyzed by GD-OES. The thickness of the layers, nano-hardness, roughness, wear resistance and coefficient of friction were measured. Finally, the anti-bacterial efficacy of the coatings was determined following the JIS Z-2801:2010 Standard. The results provide clear insights into the efficacy of silver for antibacterial purposes, as well as on its influence in the mechanical and tribological behaviour of the coatings matrix.

  19. Microfibrous silver-coated polymeric scaffolds with tunable mechanical properties

    KAUST Repository

    Kalakonda, Parvathalu.

    2017-07-07

    Electrospun scaffolds of poly(glycerol sebacate)/poly(ε-caprolactone) (PGS/PCL) have been used for engineered tissues due to their desirable thermal and mechanical properties as well as their tunable degradability. In this paper, we fabricated micro-fibrous scaffolds from a composite of PGS/PCL using a standard electrospinning method and coated them with silver (Ag). The low temperature coating method prevented substrate melting and the Ag coating decreases the pore size and increases the diameter of fibers which resulted in enhanced thermal and mechanical properties. We further compared the mechanical properties of the composite fibrous scaffolds with different thicknesses of Ag coated scaffolds. The composite fibrous scaffold with a 275 nm Ag coating showed higher tensile modulus (E) and ultimate tensile strength (UTS) without any post-processing treatment. Lastly, potential controlled release of the Ag coating from the composite fibrous scaffolds could present interesting biomedical applications.

  20. Quench dynamics in silver coated YBCO tapes

    Science.gov (United States)

    Duckworth, R. C.; Pfotenhauer, J. M.; Lue, J. W.; Gouge, M. J.; Lee, D. F.; Kroeger, D. M.

    2002-05-01

    The role of silver in the quench dynamics of RABiTS-processed YBCO tapes was examined. The voltage distribution along the 20 cm long YBCO tapes with silver thickness between two and eight micrometers was measured when different transport current pulses were applied. Measurements on each sample were performed in a conduction-cooling environment at approximately 50 K. After normal regions were induced in the sample by short over-current pulses, an operating current was applied to monitor the sample recovery or quench. When scaled to the lowest critical current, a thermal runaway current was identified and found to increase with increasing silver thickness. A simple one-dimensional model of the system supported this trend. [This paper is also published in Advances in Cryogenic Engineering Volume 47A, AIP Conference Proceedings Volume 613, pp. 449-456.

  1. Antimicrobial titanium/silver PVD coatings on titanium

    Directory of Open Access Journals (Sweden)

    Thull Roger

    2006-03-01

    Full Text Available Abstract Background Biofilm formation and deep infection of endoprostheses is a recurrent complication in implant surgery. Post-operative infections may be overcome by adjusting antimicrobial properties of the implant surface prior to implantation. In this work we described the development of an antimicrobial titanium/silver hard coating via the physical vapor deposition (PVD process. Methods Coatings with a thickness of approximately 2 μm were deposited on titanium surfaces by simultaneous vaporisation of both metals in an inert argon atmosphere with a silver content of approximately 0.7 – 9% as indicated by energy dispersive X-ray analysis. On these surfaces microorganisms and eukaryotic culture cells were grown. Results The coatings released sufficient silver ions (0.5–2.3 ppb when immersed in PBS and showed significant antimicrobial potency against Staphylococcus epidermis and Klebsiella pneumoniae strains. At the same time, no cytotoxic effects of the coatings on osteoblast and epithelial cells were found. Conclusion Due to similar mechanical performance when compared to pure titanium, the TiAg coatings should be suitable to provide antimicrobial activity on load-bearing implant surfaces.

  2. Silver coated aluminium microrods as highly colloidal stable SERS platforms.

    Science.gov (United States)

    Pazos-Perez, Nicolas; Borke, Tina; Andreeva, Daria V; Alvarez-Puebla, Ramon A

    2011-08-01

    We report on the fabrication of a novel material with the ability to remain in solution even under the very demanding conditions required for structural and dynamic characterization of biomacromolecule assays. This stability is provided by the increase in surface area of a low density material (aluminium) natively coated with a very hydrophilic surface composed of aluminium oxide (Al(2)O(3)) and metallic silver nanoparticles. Additionally, due to the dense collection of active hot spots on their surface, this material offers higher levels of SERS intensity as compared with the same free and aggregated silver nanoparticles.

  3. Hydroxyapatite-silver nanoparticles coatings on porous polyurethane scaffold.

    Science.gov (United States)

    Ciobanu, Gabriela; Ilisei, Simona; Luca, Constantin

    2014-02-01

    The present paper is focused on a study regarding the possibility of obtaining hydroxyapatite-silver nanoparticle coatings on porous polyurethane scaffold. The method applied is based on a combined strategy involving hydroxyapatite biomimetic deposition on polyurethane surface using a Supersaturated Calcification Solution (SCS), combined with silver ions reduction and in-situ crystallization processes on hydroxyapatite-polyurethane surface by sample immersing in AgNO3 solution. The morphology, composition and phase structure of the prepared samples were characterized by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD), UV-Vis spectroscopy and X-ray photoelectron spectroscopy (XPS) measurements. The data obtained show that a layer of hydroxyapatite was deposited on porous polyurethane support and the silver nanoparticles (average size 34.71 nm) were dispersed among and even on the hydroxyapatite crystals. Hydroxyapatite/polyurethane surface acts as a reducer and a stabilizing agent for silver ions. The surface plasmon resonance peak in UV-Vis absorption spectra showed an absorption maximum at 415 nm, indicating formation of silver nanoparticles. The hydroxyapatite-silver polyurethane scaffolds were tested against Staphylococcus aureus and Escherichia coli and the obtained data were indicative of good antibacterial properties of the materials.

  4. Hydroxyapatite-silver nanoparticles coatings on porous polyurethane scaffold

    Energy Technology Data Exchange (ETDEWEB)

    Ciobanu, Gabriela, E-mail: gciobanu03@yahoo.co.uk; Ilisei, Simona; Luca, Constantin

    2014-02-01

    The present paper is focused on a study regarding the possibility of obtaining hydroxyapatite-silver nanoparticle coatings on porous polyurethane scaffold. The method applied is based on a combined strategy involving hydroxyapatite biomimetic deposition on polyurethane surface using a Supersaturated Calcification Solution (SCS), combined with silver ions reduction and in-situ crystallization processes on hydroxyapatite-polyurethane surface by sample immersing in AgNO{sub 3} solution. The morphology, composition and phase structure of the prepared samples were characterized by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD), UV-Vis spectroscopy and X-ray photoelectron spectroscopy (XPS) measurements. The data obtained show that a layer of hydroxyapatite was deposited on porous polyurethane support and the silver nanoparticles (average size 34.71 nm) were dispersed among and even on the hydroxyapatite crystals. Hydroxyapatite/polyurethane surface acts as a reducer and a stabilizing agent for silver ions. The surface plasmon resonance peak in UV-Vis absorption spectra showed an absorption maximum at 415 nm, indicating formation of silver nanoparticles. The hydroxyapatite-silver polyurethane scaffolds were tested against Staphylococcus aureus and Escherichia coli and the obtained data were indicative of good antibacterial properties of the materials. - Highlights: • The hydroxyapatite and silver nanoparticles were grown on the polyurethane scaffold • The hydroxyapatite/polyurethane acts as reducing agent, stabilizer and matrix for Ag • The samples were well characterized by SEM-EDX, XRD, XPS, UV-visible spectroscopy • The hydroxyapatite/silver polyurethane scaffold shows antibacterial property.

  5. Nanofibrous Silver-Coated Polymeric Scaffolds with Tunable Electrical Properties

    Directory of Open Access Journals (Sweden)

    Adnan Memic

    2017-03-01

    Full Text Available Electrospun micro- and nanofibrous poly(glycerol sebacate-poly(ε-caprolactone (PGS-PCL substrates have been extensively used as scaffolds for engineered tissues due to their desirable mechanical properties and their tunable degradability. In this study, we fabricated micro/nanofibrous scaffolds from a PGS-PCL composite using a standard electrospinning approach and then coated them with silver (Ag using a custom radio frequency (RF sputtering method. The Ag coating formed an electrically conductive layer around the fibers and decreased the pore size. The thickness of the Ag coating could be controlled, thereby tailoring the conductivity of the substrate. The flexible, stretchable patches formed excellent conformal contact with surrounding tissues and possessed excellent pattern-substrate fidelity. In vitro studies confirmed the platform’s biocompatibility and biodegradability. Finally, the potential controlled release of the Ag coating from the composite fibrous scaffolds could be beneficial for many clinical applications.

  6. Double Glow Plasma Surface Alloying Antibacterial Silver Coating on Pure Titanium

    Science.gov (United States)

    Lin, Naiming; Guo, Junwen; Hang, Ruiqiang; Zou, Jiaojuan; Tang, Bin

    2014-12-01

    In order to endow the commercial pure titanium dental implant material with antibacterial property and aimed at avoiding the invalidation that is caused by bacterial adhesion on the surface, a silver coating was fabricated via double glow plasma surface alloying. The antibacterial property of the silver coating was assessed via in vitro estimation. The results showed that a continuous and compact coating was formed. The silver coating had absolute superiority in antibacterial property to raw commercial pure titanium. Double glow plasma surface alloying with silver on commercial pure titanium dental implant material could be considered as a potentially effective method for preventing bacterial adhesion.

  7. On the emissivity of silver coated panels, effect of long term stability and effect of coating thickness

    Energy Technology Data Exchange (ETDEWEB)

    Ageladarakis, P.; Obert, W

    1999-01-01

    Silver plated panels have been extensively used for the LHe surfaces of JET's largest cryopumps for more than 15 years now. ITER, the next-generation fusion device, also favours silver plated shields for its cryostat and vacuum vessel. This paper is concerned with the effect of ageing, coating thickness, temperature, moisture and corrosion on the emissivity of silver coated stainless steel samples, as a measure of optimisation for both performance and cost issues. (author)

  8. Comparison of toxicity of uncoated and coated silver nanoparticles

    Science.gov (United States)

    Nguyen, K. C.; Seligy, V. L.; Massarsky, A.; Moon, T. W.; Rippstein, P.; Tan, J.; Tayabali, A. F.

    2013-04-01

    This study compares toxic effects of uncoated (20, 40, 60 and 80 nm) and OECD (Organization for Economic Co-operation and Development) standard citrate- and polyvinylpyrrolidone (PVP)-coated (10, 50, and 75 nm) silver nanoparticles (Ag-NPs) in J774A. 1 macrophage and HT29 epithelial cells. The cells were exposed to different concentrations (silver content) of Ag-NPs for 24 h. Analysis showed that uncoated Ag-NPs, at a concentration of 1 μg/ml, decreased cell viability by 20-40% and that 20 and 40 nm particles were 10% more cytotoxic than the 60 and 80 nm particles. In exposures to coated Ag-NPs, cell viability dropped at 25 μg/ml or higher concentrations, and the effects were also size-dependent. PVP-coated particles induced greater cytotoxicity than citrate-coated particles. Changes in sub-cellular architecture were observed in J774A. 1 cells upon exposure to test Ag-NPs. Furthermore, uncoated Ag-NPs (1 μg/mL) decreased the expression of selected cytokines including TNF-α, IL-1β, and IL-12 (p70) in J774A. 1 and IL-8 in HT29 cells. In contrast, both citrate- and PVP-coated Ag-NPs increased the expression of these cytokines at higher concentrations (25 μg/ml), and PVP-coated particles elevated cytokine levels the most. Moreover, while uncoated Ag-NPs resulted in decreased glutathione (GSH) content and increased superoxide dismutase (SOD) activity in test cells in a size-dependent manner at 1 μg/ml, coated Ag-NPs caused non-significant changes in GSH and SOD, even at the highest test concentrations. Lastly, uncoated (20 and 40 nm) at 1 μg/ml and coated Ag-NPs (10 nm PVP) at 50 μg/ml slightly increased the production of reactive oxygen species (ROS). Our data showed that uncoated Ag-NPs are more toxic than coated Ag-NPs. While uncoated Ag-NPs appear to suppress inflammatory responses and enhance oxidative stress in the test cells, coated Ag-NPs induce toxic effects through up-regulation of cytokines. Our findings support the toxicity of Ag-NPs as being size

  9. Preparation and microwave shielding property of silver-coated carbonyl iron powder

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Xiao Guo, E-mail: xgcao@gdut.edu.cn [School of Materials and Energy, Guangdong University of Technology, Guangzhou 510006, Guangdong (China); Ren, Hao [Guangzhou Research Institute of O-M-E Technology, Guangzhou 510006, Guangdong (China); Zhang, Hai Yan [School of Materials and Energy, Guangdong University of Technology, Guangzhou 510006, Guangdong (China)

    2015-05-15

    Highlights: • The silver-coated carbonyl iron powder is prepared by the electroless plating process. • The silver-coated carbonyl iron powder is a new kind of conductive filler. • The reflection and absorption dominate the shielding mechanism of the prepared powder. • Increasing the thickness of electroconductive adhesive will increase the SE. - Abstract: Electroless silver coating of carbonyl iron powder is demonstrated in the present investigation. The carbonyl iron powders are characterized by scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction analysis (XRD) before and after the coating process. The relatively uniform and continuous silver coating is obtained under the given coating conditions. In this paper, the electromagnetic interference (EMI) shielding mechanism of the silver-coated carbonyl iron powder is suggested. The reflection of silver coating and absorption of carbonyl iron powder dominate the shielding mechanism of the silver-coated carbonyl iron powder. The silver-coated carbonyl iron powders are used as conductive filler in electroconductive adhesive for electromagnetic interference shielding applications. The effect of the thickness of electroconductive adhesive on the shielding effectiveness (SE) is investigated. The results indicate that the SE increases obviously with the increase of the thickness of electroconductive adhesive. The SE of the electroconductive adhesive with 0.35 mm thickness is above 38 dB across the tested frequency range.

  10. Evaluation of Osseous Integration of PVD-Silver-Coated Hip Prostheses in a Canine Model

    Directory of Open Access Journals (Sweden)

    Gregor Hauschild

    2015-01-01

    Full Text Available Infection associated with biomaterials used for orthopedic prostheses remains a serious complication in orthopedics, especially tumor surgery. Silver-coating of orthopedic (megaprostheses proved its efficiency in reducing infections but has been limited to surface areas exposed to soft tissues due to concerns of silver inhibiting osseous integration of cementless stems. To close this gap in the bactericidal capacity of silver-coated orthopedic prostheses extension of the silver-coating on surface areas intended for osseous integration seems to be inevitable. Our study reports about a PVD- (physical-vapor-deposition- silver-coated cementless stem in a canine model for the first time and showed osseous integration of a silver-coated titanium surface in vivo. Radiological, histological, and biomechanical analysis revealed a stable osseous integration of four of nine stems implanted. Silver trace elemental concentrations in serum did not exceed 1.82 parts per billion (ppb and can be considered as nontoxic. Changes in liver and kidney functions associated with the silver-coating could be excluded by blood chemistry analysis. This was in accordance with very limited metal displacement from coated surfaces observed by laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS 12 months after implantation. In conclusion our results represent a step towards complete bactericidal silver-coating of orthopedic prostheses.

  11. Unmasking the Effects of L-DOPA on Rapid Dopamine Signaling with an Improved Approach for Nafion Coating Carbon-Fiber Microelectrodes.

    Science.gov (United States)

    Qi, Lingjiao; Thomas, Elina; White, Stephanie H; Smith, Samantha K; Lee, Christie A; Wilson, Leslie R; Sombers, Leslie A

    2016-08-16

    L-DOPA has been the gold standard for symptomatic treatment of Parkinson's disease. However, its efficacy wanes over time as motor complications develop. Very little is known about how L-DOPA therapy affects the dynamics of fluctuating dopamine concentrations in the striatum on a rapid time scale (seconds). Electrochemical studies investigating the effects of L-DOPA treatment on electrically evoked dopamine release have reported conflicting results with significant variability. We hypothesize that the uncertainty in the electrochemical data is largely due to electrode fouling caused by polymerization of L-DOPA and endogenous catecholamines on the electrode surface. Thus, we have systematically optimized the procedure for fabricating cylindrical, Nafion-coated, carbon-fiber microelectrodes. This has enabled rapid and reliable detection of L-DOPA's effects on striatal dopamine signaling in intact rat brain using fast-scan cyclic voltammetry. An acute dose of 5 mg/kg L-DOPA had no significant effect on dopamine dynamics, demonstrating the highly efficient regulatory mechanisms at work in the intact brain. In contrast, administration of 200 mg/kg L-DOPA significantly increased the amplitude of evoked dopamine release by ∼200%. Overall, this work describes a reliable tool that allows a better measure of L-DOPA augmented dopamine release in vivo, measured using fast-scan cyclic voltammetry. It provides a methodology that improves the stability and performance of the carbon-fiber microelectrode when studying the molecular mechanisms underlying L-DOPA therapy and also promises to benefit a wide variety of studies because Nafion is so commonly used in electroanalytical chemistry.

  12. Study of electroplated silver-palladium biofouling inhibiting coating

    DEFF Research Database (Denmark)

    Chiang, Wen-Chi; Hilbert, Lisbeth Rischel; Møller, Per

    , a new coating has been designed to form an inhibiting effect on the surface by itself. In this way, it is desired that the release of any matter will be in low concentration. This design is based on silver combined with nobler palladium, both with catalytic properties. Due to the potential difference......The undesired microbial and biofilm adhesions on the surfaces of food industrial facilities, water supply systems and etc. are so called as “biofouling”. Biofouling can cause many undesirable effects. Until now for solving biofouling, there are few non-toxic inhibiting treatments. In this study...... between silver and palladium while contacting with an electrolyte, the surface can form numerous discrete anodic and cathodic areas, so that an inhibiting reaction can be formed. In this paper, a series of electrochemical and biological tests were conducted to study the properties of these surfaces...

  13. Preparation of Silver-Coated Polystyrene Composite Particles

    Institute of Scientific and Technical Information of China (English)

    陈卓; 詹鹏; 章建辉; 王振林; 章维益; 闵乃本

    2003-01-01

    We report a feasible approach to the preparation of monodispersed metal-shell composite microspheres based on a combination of surface reaction and surface seeding techniques. The method was implemented for coating polystyrene (PS) spheres with silver shell having a variable thickness by controlling the amount of reagents in the reaction procedure. These composite spherical particles in dimensions of the submicrometer range may become attractive building blocks for the creation of metallo-dielectric photonic band gap materials when they are organized into crystals.

  14. Prevention of primary vascular graft infection with silver-coated polyester graft in a porcine model

    DEFF Research Database (Denmark)

    Gao, H; Sandermann, J; Prag, J;

    2010-01-01

    To evaluate the efficacy of a silver-coated vascular polyester graft in the prevention of graft infection after inoculation with Staphylococcus aureus in a porcine model.......To evaluate the efficacy of a silver-coated vascular polyester graft in the prevention of graft infection after inoculation with Staphylococcus aureus in a porcine model....

  15. Nafion as Cosurfactant: Solubilization of Nafion in Water in the Presence of Pluronics

    KAUST Repository

    Kelarakis, Antonios

    2011-01-18

    Incorporation of Nafion to aqueous solutions of Pluronics adversely impacts micellization due to extensive Nafion/copolymer interactions. Light scattering and zeta potential measurements provide evidence for the formation of sizable and stable Nafion/copolymer complexes, in expense of the neat copolymer micelles. At high copolymer concentrations, the overall interaction diagram of Nafion/copolymer reflects the competitive action of the release of packing constraints due to micellar destabilization induced by Nafion on one hand and the gelator nature of the Nafion on the other. Measurements using a quartz crystal microbalance (QCM-D) show that aqueous solutions of Pluronics (even at very low concentration) can dissolve the Nafion coating on the crystal resonator, while typical low molecular weight ionic surfactants fail to induce similar effects. These studies demonstrate that complexation with this class of copolymers is a facile route to impart dispersibility to Nafion in aqueous environments that otherwise can be achieved through tedious and harsh treatments. © 2010 American Chemical Society.

  16. Silver-polysaccharide nanocomposite antimicrobial coatings for methacrylic thermosets.

    Science.gov (United States)

    Travan, Andrea; Marsich, Eleonora; Donati, Ivan; Benincasa, Monica; Giazzon, Marta; Felisari, Laura; Paoletti, Sergio

    2011-01-01

    Bisphenol A glycidylmethacrylate (BisGMA)/triethyleneglycol dimethacrylate (TEGDMA) thermosets are receiving increasing attention as biomaterials for dental and orthopedic applications; for both these fields, bacterial adhesion to the surface of the implant represents a major issue for the outcome of the surgical procedure. Moreover, the biological behaviour of these materials is influenced by their ability to establish proper interactions between their surface and the eukaryotic cells of the surrounding tissues, which is important for good implant integration. The aim of this work was to develop an antimicrobial non-cytotoxic coating for methacrylic thermosets by means of a nanocomposite material based on a lactose-modified chitosan and antibacterial silver nanoparticles. The coating was characterized by UV-vis spectrophotometry, optical microscopy, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). In vitro tests were employed for a biological characterization of the material: antimicrobial efficacy tests were carried out with both Gram+ and Gram- strains. Osteoblast-like cell-lines, primary human fibroblasts and adipose-derived stem cells, were used for LDH cytotoxicity assays and Alamar blue cell proliferation assays. Cell morphology and distribution were evaluated by SEM and confocal laser scanning microscopy. In vitro results showed that the nanocomposite coating is effective in killing both bacterial strains and that this material does not exert any significant cytotoxic effect towards tested cells, which are able to firmly attach and proliferate on the surface of the coating. Such biocompatible antimicrobial polymeric films containing silver nanoparticles may have good potential for surface modification of medical devices, especially for prosthetic applications in orthopedics and dentistry.

  17. Antimicrobial beeswax coated polylactide films with silver control release capacity.

    Science.gov (United States)

    Martínez-Abad, Antonio; Lagarón, Jose Maria; Ocio, María Jose

    2014-03-17

    Although the application of silver based antimicrobial systems is a widespread technology, its implementation in areas such as food packaging is still challenging. The present paper describes the fabrication of poly(lactic acid) (PLA) coated with beeswax with controlled release properties for sustained antimicrobial performance. Release of silver ions from the polymers was monitored voltammetrically under various conditions (surface contact, immersion in various liquid media and at different pH values) throughout at least 7days. A higher release was noted with decreasing pH while surface release was much slower than the release when immersed in liquid medium. While uncoated films demonstrated a high burst release which in some instances implied surpassing some current migration restrictions (beeswax layer allowed a sustained release of the antimicrobial compound. Increasing the thickness of the beeswax layer resulted in an increase in the water barrier properties of the films while reducing the relatively constant values of sustained release. Antimicrobial performance was correlated with the release of silver ions, indicating threshold concentrations for biocide action of <6μg/L and 9-14μg/L for surface contact and in liquid media, respectively. Either by surface contact or by immersion in growth medium or vegetable soup, the coated films displayed a strong bactericidal effect against Salmonella enterica. The application of this functional barrier thus offers the possibility of tuning the release profiles of the films to suit a specific application and puts forth the possible suitability of these materials for food packaging or other migration sensitive applications.

  18. Update on UCO's advanced coating lab development of silver-based mirror coatings

    Science.gov (United States)

    Phillips, Andrew C.; Fryauf, David M.; Kobayashi, Nobuhiko P.; DuPraw, Brian; Cheleden, Spencer; Ratliff, Christopher; Bolte, Michael J.; Cowley, David

    2016-08-01

    We present progress in efforts underway at the University of California Observatories to develop high performance durable silver-based mirror coatings for telescope and instruments. Silver-based coatings are extremely prone to tarnish and/or corrosion, and successful coatings depend not only on the materials used but also the deposition processes employed. Our physical vapor deposition (PVD) chamber allows both sputtering and ion-assisted e-beam depositions for head-to-head comparison of deposition processes, and we present results of these comparisons. In this paper, we review the problem and discuss our recent activities and findings. We discuss a systematic study to determine which oxides, nitrides and fluorides provide the best protection in environmental tests. We present initial results into the effects of stress in our specific thin films, and thee effects of stress on mirror coating durability. We also discuss studies using Atomic Layer Deposition (ALD) over-coating of Ag, and we describe a large ALD research chamber currently under construction that will demonstrate ALD processes on larger substrates (70 cm diameter).

  19. Size-Controlled Dissolution of Organic-Coated Silver Nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Rui; Levard, Clément; Marinakos, Stella M.; Cheng, Yingwen; Liu, Jie; Michel, F. Marc; Brown, Jr., Gordon E.; Lowry, Gregory V. (Duke)

    2012-04-02

    The solubility of Ag NPs can affect their toxicity and persistence in the environment. We measured the solubility of organic-coated silver nanoparticles (Ag NPs) having particle diameters ranging from 5 to 80 nm that were synthesized using various methods, and with different organic polymer coatings including poly(vinylpyrrolidone) and gum arabic. The size and morphology of Ag NPs were characterized by transmission electron microscopy (TEM). X-ray absorption fine structure (XAFS) spectroscopy and synchrotron-based total X-ray scattering and pair distribution function (PDF) analysis were used to determine the local structure around Ag and evaluate changes in crystal lattice parameters and structure as a function of NP size. Ag NP solubility dispersed in 1 mM NaHCO{sub 3} at pH 8 was found to be well correlated with particle size based on the distribution of measured TEM sizes as predicted by the modified Kelvin equation. Solubility of Ag NPs was not affected by the synthesis method and coating as much as by their size. Based on the modified Kelvin equation, the surface tension of Ag NPs was found to be {approx}1 J/m{sup 2}, which is expected for bulk fcc (face centered cubic) silver. Analysis of XAFS, X-ray scattering, and PDFs confirm that the lattice parameter, {alpha}, of the fcc crystal structure of Ag NPs did not change with particle size for Ag NPs as small as 6 nm, indicating the absence of lattice strain. These results are consistent with the finding that Ag NP solubility can be estimated based on TEM-derived particle size using the modified Kelvin equation for particles in the size range of 5-40 nm in diameter.

  20. Size-controlled dissolution of organic-coated silver nanoparticles.

    Science.gov (United States)

    Ma, Rui; Levard, Clément; Marinakos, Stella M; Cheng, Yingwen; Liu, Jie; Michel, F Marc; Brown, Gordon E; Lowry, Gregory V

    2012-01-17

    The solubility of Ag NPs can affect their toxicity and persistence in the environment. We measured the solubility of organic-coated silver nanoparticles (Ag NPs) having particle diameters ranging from 5 to 80 nm that were synthesized using various methods, and with different organic polymer coatings including poly(vinylpyrrolidone) and gum arabic. The size and morphology of Ag NPs were characterized by transmission electron microscopy (TEM). X-ray absorption fine structure (XAFS) spectroscopy and synchrotron-based total X-ray scattering and pair distribution function (PDF) analysis were used to determine the local structure around Ag and evaluate changes in crystal lattice parameters and structure as a function of NP size. Ag NP solubility dispersed in 1 mM NaHCO(3) at pH 8 was found to be well correlated with particle size based on the distribution of measured TEM sizes as predicted by the modified Kelvin equation. Solubility of Ag NPs was not affected by the synthesis method and coating as much as by their size. Based on the modified Kelvin equation, the surface tension of Ag NPs was found to be ∼1 J/m(2), which is expected for bulk fcc (face centered cubic) silver. Analysis of XAFS, X-ray scattering, and PDFs confirm that the lattice parameter, a, of the fcc crystal structure of Ag NPs did not change with particle size for Ag NPs as small as 6 nm, indicating the absence of lattice strain. These results are consistent with the finding that Ag NP solubility can be estimated based on TEM-derived particle size using the modified Kelvin equation for particles in the size range of 5-40 nm in diameter.

  1. Natural tubule clay template synthesis of silver nanorods for antibacterial composite coating.

    Science.gov (United States)

    Abdullayev, Elshad; Sakakibara, Keita; Okamoto, Ken; Wei, Wenbo; Ariga, Katsuhiko; Lvov, Yuri

    2011-10-01

    Halloysite is naturally available clay mineral with hollow cylindrical geometry and it is available in thousands of tons. Silver nanorods were synthesized inside the lumen of the halloysite by thermal decomposition of the silver acetate, which was loaded into halloysite from an aqueous solution by vacuum cycling. Images of individual ca. 15 nm diameter silver nanorods and nanoparticles were observed with TEM. The presence of silver inside the tubes was also verified with STEM-EDX elemental mapping. Nanorods had crystalline nature with [111] axis oriented ~68° from the halloysite tubule main axis. The composite of silver nanorods encased in clay tubes with the polymer paint was prepared, and the coating antimicrobial activity combined with tensile strength increase was demonstrated. Coating containing up 5% silver loaded halloysite did not change color after light exposure contrary to the sample prepared with loading with unshelled silver nanoparticles. Halloysite tube templates have a potential for scalable manufacturing of ceramic encapsulated metal nanorods for composite materials.

  2. Antibacterial Properties of Silver-Loaded Plasma Polymer Coatings

    Directory of Open Access Journals (Sweden)

    Lydie Ploux

    2012-01-01

    Full Text Available In a previous paper, we proposed new silver nanoparticles (SNPs based antibacterial coatings able to protect eukaryotic cells from SNPs related toxic effects, while preserving antibacterial efficiency. A SNPs containing n-heptylamine (HA polymer matrix was deposited by plasma polymerization and coated by a second HA layer. In this paper, we elucidate the antibacterial action of these new coatings. We demonstrated that SNPs-loaded material can be covered by thin HA polymer layer without losing the antibacterial activity to planktonic bacteria living in the near surroundings of the material. SNPs-containing materials also revealed antibacterial effect on adhered bacteria. Adhered bacteria number was significantly reduced compared to pure HA plasma polymer and the physiology of the bacteria was affected. The number of adhered bacteria directly decreased with thickness of the second HA layer. Surprisingly, the quantity of cultivable bacteria harvested by transfer to nutritive agar decreased not only with the presence of SNPs, but also in relation to the covering HA layer thickness, that is, oppositely to the increase in adhered bacteria number. Two hypotheses are proposed for this surprising result (stronger attachment or weaker vitality, which raises the question of the diverse potential ways of action of SNPs entrapped in a polymer matrix.

  3. Assessing antibacterial effect of filter media coated with silver nanoparticles against Bacillus spp

    Directory of Open Access Journals (Sweden)

    Mahmood Nafisi Bahabadi

    2016-04-01

    Full Text Available Background: Nanotechnology is a field of applied science and technology covering a broad range of topics. Use of nanotechnology and especially silver nanoparticles in control of bacterial diseases and infections has been studied in the recent years. The aim of the present study was to investigate the in vitro antibacterial effect of filter media coated with silver nanoparticles against Bacillus spp. Materials and methods: In this research, first, the antibacterial effects of silver nanoparticles against mentioned bacteria were evaluated by microdilution method in Broth medium. After confidence of inhibitory effect of colloidal silver nanoparticles, antibacterial effect of filter media coated with silver nanoparticles was evaluated via in vitro microbiology tests (zone of inhibition test and test tube test. Results: Present study showed that colloidal silver nanoparticles have good antimicrobial effects against tested bacteria, so that MIC and MBC of silver nanoparticles for Bacillus spp. were calculated 3.9 and 31.25 mg/L, respectively. Also significant decrease was observed in bacterial growth after exposure to filter media coated with silver nanoparticles in test tube test and  zone of inhibition test (P≤ 5%. Conclusion: The results of this research indicate that filter media coated with silver nanoparticles have considerable antimicrobial effects; therefore they could possibly be used as excellent antibacterial water filters and would have several applications in other sectors.

  4. Antimicrobial particulate silver coatings on stainless steel implants for fracture management

    Energy Technology Data Exchange (ETDEWEB)

    DeVasConCellos, Paul; Bose, Susmita [W.M. Keck Biomedical Materials Research Laboratory, School of Mechanical and Materials Engineering, Washington State University, Pullman, WA (United States); Beyenal, Haluk [School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA (United States); Bandyopadhyay, Amit, E-mail: amitband@wsu.edu [W.M. Keck Biomedical Materials Research Laboratory, School of Mechanical and Materials Engineering, Washington State University, Pullman, WA (United States); Zirkle, Lewis G. [Surgical Implant Generation Network (SIGN), Richland, WA (United States)

    2012-07-01

    We have used particulate silver coating on stainless steel to prevent in vivo bacterial infection. Stainless steel is commonly used as an implant material for fracture management. The antimicrobial use of silver has been well documented and studied, therefore the novelty of this research is the use of a particulate coating as well as facing the real world challenges of a fracture repair implant. The variable parameters for applying the coating were time of deposition, silver solution concentration, voltage applied, heat treatment temperature between 400 and 500 Degree-Sign C and time. The resultant coating is shown to be non-toxic to human osteoblasts using an MTT assay for proliferation and SEM images for morphology. In vitro silver release studies of various treatments were done using simulated body fluid. The bactericidal effects were tested by challenging the coatings with Pseudomonas aeruginosa in a bioreactor and compared against uncoated stainless steel. A 13-fold reduction in bacteria was observed at 24 h and proved to be statistically significant. - Highlights: Black-Right-Pointing-Pointer Processing of particulate silver coating that are strongly adherent on SS surface. Black-Right-Pointing-Pointer Optimized the amount of silver that is sufficient to reduce bacterial colonization but non-toxic to human bone tissue. Black-Right-Pointing-Pointer The adhesion strength of silver was sufficient to survive industrial sterilization steps used for fracture management devices.

  5. Preparation and in-vitro Antibacterial Evaluation of Electroless Silver Coated Polymers.

    Science.gov (United States)

    Fazeli, Mohammad Reza; Hosseini, Vahid; Shamsa, Fazel; Jamalifar, Hossein

    2010-01-01

    Long-term use of indwelling medical catheters has often been hindered by catheter-associated nosocomial infections. In this study the effectiveness of silver coating of polystyrene and polyethylene polymers was investigated. Polymer pieces of 2 cm(2) each were coated with a thin layer of silver using electroless plating technique. Silver-coated polymers were challenged with cultures of four different microorganisms known for their involvement in nosocomial infections in both solid and broth media. The tested bacteria included Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli and Pseudomonas aeruginosa. Silver release from the coated polymers was 2-5 μg/cm(2) which was confirmed by chemical and biological methods. The silver coating thickness ranged between 20-450 nm. P. aeruginosa and S. aureus were the most adherent bacteria to polystyrene sheets while E. coli showed minimum adherence effect. The survival rate of different bacteria after 80 min in a time course experiment tended to dominate E. coli as the most sensitive bacteria to the effect of silver with zero survival rate while around 4% of P. aeruginosa were detected after same period. Silver coating of indwelling polymers by electroless technique seems promising in combating nosocomial infections due to long-term catheterization.

  6. Air-stable silver-coated copper particles of sub-micrometer size.

    Science.gov (United States)

    Jung, D S; Lee, H M; Kang, Y C; Park, S B

    2011-12-15

    Silver-coated copper particles with various silver loading were prepared by a direct liquid-to-particle conversion process in spray pyrolysis reactor system. The prepared particles were completely densified at 900°C within a residence time of 2.1 s and had core-shell structure, of which formation mechanism was proposed. The mean diameter of particles was 0.45 μm. Copper particles of 20 wt.% of silver loading were stable under air and 95% of copper remained as metallic copper even after 1 month of exposure to air. This enhanced air-stability contributed to the enhanced electrical property of conductive film obtained from the coated particles. The conductive film obtained from 15 wt.% of silver-coated copper particles had a sheet resistance of 1.2 mΩ square(-1). This low resistance resulted from the lack of oxide layer and low sintering temperature of silver layer.

  7. Preparation of silver-coated glass frit and its application in silicon solar cells

    Science.gov (United States)

    Feng, Xiang; Biyuan, Li; Yingfen, Li; Jian, Zhou; Weiping, Gan

    2016-07-01

    A simple electroless plating process was employed to prepare silver-coated glass frits for solar cells. The surface of the glass frits was modified with polyvinyl-pyrrolidone (PVP) before the electroless plating process. Infrared (IR) spectroscopy, field emission scanning electron microscopy (FESEM), and x-ray diffraction (XRD) were used to characterize the PVP modified glass frits and investigate the mechanism of the modification process. It was found that the PVP molecules adsorbed on the glass frit surface and reduced the silver ions to the silver nanoparticles. Through epitaxial growth, these nanoparticles were uniformly deposited onto the surface of the glass frit. Silicon solar cells with this novel silver coating exhibited a photoelectric conversion efficiency increase of 0.33%. Compared with the electroless plating processes, this method provides a simple route to prepare silver-coated glass frits without introducing impurity ions.

  8. Preparation of silver-coated glass frit and its application in silicon solar cells

    Institute of Scientific and Technical Information of China (English)

    向锋; 李碧渊; 黎应芬; 周健; 甘卫平

    2016-01-01

    A simple electroless plating process was employed to prepare silver-coated glass frits for solar cells. The surface of the glass frits was modified with polyvinyl-pyrrolidone (PVP) before the electroless plating process. Infrared (IR) spectroscopy, field emission scanning electron microscopy (FESEM), and x-ray diffraction (XRD) were used to characterize the PVP modified glass frits and investigate the mechanism of the modification process. It was found that the PVP molecules adsorbed on the glass frit surface and reduced the silver ions to the silver nanoparticles. Through epitaxial growth, these nanoparticles were uniformly deposited onto the surface of the glass frit. Silicon solar cells with this novel silver coating exhibited a photoelectric conversion efficiency increase of 0.33%. Compared with the electroless plating processes, this method provides a simple route to prepare silver-coated glass frits without introducing impurity ions.

  9. Toxicity of silver ions and differently coated silver nanoparticles in Allium cepa roots.

    Science.gov (United States)

    Cvjetko, Petra; Milošić, Anita; Domijan, Ana-Marija; Vinković Vrček, Ivana; Tolić, Sonja; Peharec Štefanić, Petra; Letofsky-Papst, Ilse; Tkalec, Mirta; Balen, Biljana

    2017-03-01

    Silver nanoparticles (AgNPs) are the dominating nanomaterial in consumer products due to their well-known antibacterial and antifungal properties. To enhance their properties, different surface coatings may be used, which affect physico-chemical properties of AgNPs. Due to their wide application, there has been concern about possible environmental and health consequences. Since plants play a significant role in accumulation and biodistribution of many environmentally released substances, they are also very likely to be influenced by AgNPs. In this study we investigated the toxicity of AgNO3 and three types of laboratory-synthesized AgNPs with different surface coatings [citrate, polyvinylpyrrolidone (PVP) and cetyltrimethylammonium bromide (CTAB)] on Allium cepa roots. Ionic form of Ag was confirmed to be more toxic than any of the AgNPs applied. All tested AgNPs caused oxidative stress and exhibited toxicity only when applied in higher concentrations. The highest toxicity was recorded for AgNPs-CTAB, which resulted with increased Ag uptake in the roots, consequently leading to strong reduction of the root growth and oxidative damage. The weakest impact was found for AgNPs-citrate, much bigger, negatively charged NPs, which also aggregated to larger particles. Therefore, we can conclude that the toxicity of AgNPs is directly correlated with their size, overall surface charge and/or surface coating.

  10. Durable Silver Mirror Coating Via Ion Assisted, Electron Beam Evaporation For Large Aperture Optics Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In the Phase I research, Surface Optics Corporation (SOC) demonstrated a durable silver mirror coating based an ion assisted, thermal evaporation process. The recipe...

  11. Durable Silver Mirror Coating Via Ion Assisted, Electron Beam Evaporation For Large Aperture Optics Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Highly reflective optical coatings with low scatter properties are needed to image very faint objects such as extra-solar planets. Silver has the highest...

  12. New Strategies in the Development of Antimicrobial Coatings: The Example of Increasing Usage of Silver and Silver Nanoparticles

    Directory of Open Access Journals (Sweden)

    Leo H. Koole

    2011-01-01

    Full Text Available Bacterial infection from medical devices is a major problem and accounts for an increasing number of deaths as well as high medical costs. Many different strategies have been developed to decrease the incidence of medical device related infection. One way to prevent infection is by modifying the surface of the devices in such a way that no bacterial adhesion can occur. This requires modification of the complete surface with, mostly, hydrophilic polymeric surface coatings. These materials are designed to be non-fouling, meaning that protein adsorption and subsequent microbial adhesion are minimized. Incorporation of antimicrobial agents in the bulk material or as a surface coating has been considered a viable alternative for systemic application of antibiotics. However, the manifestation of more and more multi-drug resistant bacterial strains restrains the use of antibiotics in a preventive strategy. The application of silver nanoparticles on the surface of medical devices has been used to prevent bacterial adhesion and subsequent biofilm formation. The nanoparticles are either deposited directly on the device surface, or applied in a polymeric surface coating. The silver is slowly released from the surface, thereby killing the bacteria present near the surface. In the last decade there has been a surplus of studies applying the concept of silver nanoparticles as an antimicrobial agent on a range of different medical devices. The main problem however is that the exact antimicrobial mechanism of silver remains unclear. Additionally, the antimicrobial efficacy of silver on medical devices varies to a great extent. Here we will review existing antimicrobial coating strategies and discuss the use of silver or silver nanoparticles on surfaces that are designed to prevent medical device related infections.

  13. Inhibition of biofilm formation and antibacterial properties of a silver nano-coating on human dentine.

    Science.gov (United States)

    Besinis, Alexandros; De Peralta, Tracy; Handy, Richard D

    2014-11-01

    The survival of pathogenic bacteria in the oral cavity depends on their successful adhesion to dental surfaces and their ability to develop into biofilms, known as dental plaque. Bacteria from the dental plaque are responsible for the development of dental caries, gingivitis, periodontitis, stomatitis and peri-implantitis. Certain metal nanoparticles have been suggested for infection control and the management of the oral biofilm. Here, it is shown that application of a silver nano-coating directly on dentine can successfully prevent the biofilm formation on dentine surfaces as well as inhibit bacterial growth in the surrounding media. This silver nano-coating was found to be stable (>98.8%) and to maintain its integrity in biological fluids. Its antibacterial activity was compared to silver nitrate and the widely used clinical antiseptic, chlorhexidine. The bacterial growth and cell viability were quantitatively assessed by measuring the turbidity, proportion of live and dead cells and lactate production. All three bioassays showed that silver nanoparticles and silver nitrate dentine coatings were equally highly bactericidal (>99.5%), while inhibiting bacterial adhesion. However, the latter caused significant dentine discolouration (ΔE* = 50.3). The chlorhexidine coating showed no antibacterial effect. Thus, silver nanoparticles may be a viable alternative to both chlorhexidine and silver nitrate, protecting from dental plaque and secondary caries when applied as a dentine coating, while they may provide the platform for creating anti-biofilm surfaces in medical devices and other biomedical applications.

  14. A Facile Fabrication of Silver-Coated Copper Nanowires by Galvanic Replacement

    Directory of Open Access Journals (Sweden)

    Xin He

    2016-01-01

    Full Text Available We demonstrated a general strategy to fabricate silver-coated copper nanowires by a galvanic replacement, which is guided by the chemical principle that metal ions (silver ions with a relatively high reduction potential can galvanically etch nanostructure made from a less metal (copper. Well-dispersed and high-yielded copper nanowires were initially synthesized and then introduced into silver-ammonia solution for the growth of silver nanocrystals on the nanowire surfaces under vigorous oscillation. The results of X-ray diffraction, scanning electron microscope, and transmission electron microscope revealed that the silver nanocrystals were uniformly distributed on the copper nanowire surfaces to form Cu-Ag heterostructures. The concentration of silver-ammonia solution and the time of replacement reaction determine the size and density of the silver nanocrystals. Our investigation might pave the way to the synthesis of other bimetallic nanostructures via a facile, fast, and economical route.

  15. Capillary electrophoresis coupled with inductively coupled mass spectrometry as an alternative to cloud point extraction based methods for rapid quantification of silver ions and surface coated silver nanoparticles.

    Science.gov (United States)

    Qu, Haiou; Mudalige, Thilak K; Linder, Sean W

    2016-01-15

    Speciation and accurate quantification of ionic silver and metallic silver nanoparticles are critical to investigate silver toxicity and to determine the shelf-life of products that contain nano silver under various storage conditions. We developed a rapid method for quantification of silver ions and silver nanoparticles using capillary electrophoresis (CE) interfaced with inductively-coupled plasma mass spectrometry (ICPMS). The addition of 2-mercaptopropionylglycine (tiopronin) to the background electrolyte was used to facilitate the chromatographic separation of ionic silver and maintain the oxidation state of silver. The obtained limits of detection were 0.05 μg kg(-1) of silver nanoparticles and 0.03 μg kg(-1) of ionic silver. Nanoparticles of varied sizes (10-110 nm) with different surface coating, including citrate acid, lipoic acid, polyvinylpyrrolidone and bovine serum albumin (BSA) were successfully analyzed. Particularly good recoveries (>93%) were obtained for both ionic silver and silver nanoparticle in the presence of excess amount of BSA. The method was further tested with six commercially available dietary supplements which varied in concentration and matrix components. The summed values of silver ions and silver nanoparticles correlated well with the total silver concentration determined by ICPMS after acid digestion. This method can serve as an alternative to cloud point extraction technique when the extraction efficiency for protein coated nanoparticles is low.

  16. Spray-coated nanoscale conductive patterns based on in situ sintered silver nanoparticle inks

    Science.gov (United States)

    2014-01-01

    Nanoscale patterns with high conductivity based on silver nanoparticle inks were fabricated using spray coating method. Through optimizing the solution content and spray operation, accurate nanoscale patterns consisting of silver nanoparticles with a square resistance lower than 1 Ω /cm2 were obtained. By incorporating in situ sintering to substitute the general post sintering process, the time consumption could be significantly reduced to one sixth, qualifying it for large-scale and cost-effective fabrication of printed electronics. To testify the application of spray-coated silver nanoparticle inks, an inverted polymer solar cell was also fabricated, which exhibited a power conversion efficiency of 2.76%. PMID:24666992

  17. The potential of photo-deposited silver coatings on Foley catheters to prevent urinary tract infections.

    Science.gov (United States)

    Cooper, Ian Richard; Pollini, Mauro; Paladini, Federica

    2016-12-01

    Catheter-associated urinary tract infection (CAUTI) represents one of the most common causes of morbidity and mortality. The resistance demonstrated by many microorganisms to conventional antibiotic therapies and the increasing health-care costs have recently encouraged the definition of alternative preventive strategies, which can have a positive effect in the management of infections. Antimicrobial urinary catheters have been developed through the photo-chemical deposition of silver coatings on the external and luminal surfaces. The substrates are exposed to ultraviolet radiation after impregnation into a silver-based solution, thus inducing the in situ synthesis of silver particles. The effect of the surface treatment on the material was investigated through scanning electron microscopy (SEM) and silver ion release measurements. The ability of microorganisms commonly associated with urinary tract infections was investigated in terms of bacterial viability, proliferation and biofilm development, using Escherichia coli, Klebsiella pneumoniae and Proteus mirabilis as target organisms. The silver coatings demonstrated good distribution of silver particles to the substrate, and proved an effective antibacterial capability in simulated biological conditions. The low values of silver ion release demonstrated the optimum adhesion of the coating. The results indicated a good potential of silver-based antimicrobial materials for prevention of catheter-associated urinary tract infection.

  18. In vitro antibacterial and osteogenic properties of plasma sprayed silver-containing hydroxyapatite coating

    Institute of Scientific and Technical Information of China (English)

    RUAN HongJiang; FAN CunYi; ZHENG XueBin; ZHANG Yan; CHEN YiKai

    2009-01-01

    The objective of the present investigation was to characterize the antibacterial and osteogenic proper-ties of plasma sprayed silver-containing hydroxyapatite (HA/Ag) coating in vitro. HA/Ag coating was deposited via vacuum plasma spraying. The concentration of silver ions released from HA/Ag coating, the efficacy of the HA/Ag coating against bacterial biofilm development, the effect of the HA/Ag coating on early adhesion and ossification of osteoblast cells in vitro was measured. The silver ion concentra-tion released from the HA/Ag coating was between the minimum inhibitory concentration to bacteria and the cytotoxic concentration. Bacterial biofiim inhibition studies indicated an antibacterial activity on the HA/Ag coating surface when compared with hydroxyapatite (HA) coating alone. Moreover, it was demonstrated that osteoblast cell adhesion and mineralization occurred on the HA/Ag coating surface during the testing period. We conclude that the vacuum plasma sprayed HA/Ag coating possesses good antibacterial capability and osteogenic properties in vitro and represents a promising candidate for coating orthopedic implants.

  19. Effect of dyeing on antibacterial efficiency of silver coated cotton fabrics

    Science.gov (United States)

    Shahidi, Sheila; Rezaee, Sahar; Hezavehi, Emadaldin

    2014-04-01

    Despite numerous investigations during recent decades in the field of antimicrobial treating textile fibers using silver, many obscurities remain regarding the durability and dyeing ability and the influences of dyeing on the antimicrobial effectiveness of silver-treated fibers. In this research work, the cotton fabrics were sputtered using DC magnetron sputtering system for different times of exposure by silver. Then the silver coated samples were dyed by different classes of synthetic and natural dyes. The dye ability of coated samples was compared with untreated cotton. The reflective spectrophotometer was used for this purpose. The morphology of the cotton fabrics before and after dyeing was observed using a scanning electron microscope (SEM). The antibacterial activity of samples before and after dyeing, were investigated and compared. For antibacterial investigation, the antibacterial counting tests were used. It was concluded that, dyeing does not have any negative effect on antibacterial activity of coated samples and very good antibacterial activity was achieved after dyeing.

  20. Chronic Effects of Coated Silver Nanoparticles on Marine Invertebrate Larvae: A Proof of Concept Study.

    Directory of Open Access Journals (Sweden)

    Christine Ying Shan Chan

    Full Text Available Silver nanoparticles (AgNPs, owing to their unique physical and chemical properties, have become increasingly popular in consumer products. However, data on their potential biological effects on marine organisms, especially invertebrates, remain very limited. This proof of principle study reports the chronic sub-lethal toxicity of two coated AgNPs (oleic acid coated AgNPs and polyvinylpyrrolidone coated AgNPs on marine benthic invertebrate larvae across three phyla (i.e., the barnacle Balanus Amphitrite, the slipper-limpet Crepidula onyx, and the polychaete Hydroides elegans in terms of growth, development, and metamorphosis. Bioaccumulation and biodistribution of silver were also investigated. Larvae were also exposed to silver nitrate (AgNO3 in parallel to distinguish the toxic effects derived from nano-silver and the aqueous form of silver. The sub-lethal effect of chronic exposure to coated AgNPs resulted in a significant retardation in growth and development, and reduction of larval settlement rate. The larval settlement rate of H. elegans was significantly lower in the coated AgNP treatment than the AgNO3 treatment, suggesting that the toxicity of coated AgNPs might not be solely evoked by the release of silver ions (Ag+ in the test medium. The three species accumulated silver effectively from coated AgNPs as well as AgNO3, and coated AgNPs were observed in the vacuoles of epithelial cell in the digestive tract of C. onyx. Types of surface coatings did not affect the sub-lethal toxicity of AgNPs. This study demonstrated that coated AgNPs exerted toxic effects in a species-specific manner, and their exposure might allow bioaccumulation of silver, and affect growth, development, and settlement of marine invertebrate larvae. This study also highlighted the possibility that coated AgNPs could be taken up through diet and the toxicity of coated AgNPs might be mediated through toxic Ag+ as well as the novel modalities of coated AgNPs.

  1. Sol-gel-coated Electrocatalytic Dopamine Sensor Based on L-Lysine Incorporated Nafion Film%基于Nafion-L-赖氨酸-溶胶-凝胶膜的电催化型多巴胺传感器

    Institute of Scientific and Technical Information of China (English)

    梁汝萍; 邱建丁; 邹小勇; 蔡沛祥

    2003-01-01

    利用滴涂于铂盘表面的Nafion膜中负电性的磺酸基与L-赖氨酸阳离子之间的静电作用实现L-赖氨酸的固定化,再在Nafion-L-赖氨酸修饰电极表面涂布一层溶胶-凝胶薄膜,制备成Nafion-L-赖氨酸-溶胶-凝胶电催化型多巴胺传感器. 采用循环伏安法和电流-时间曲线考察了传感器的电化学特性,采用差示脉冲伏安法对多巴胺进行定量分析,线性范围为5.0×10-7~5.0×10-4 mol/L,检出限为5.0×10-8 mol/L. 该传感器制备方法简单、稳定性好、灵敏度高,且具有良好的选择性,能有效排除抗坏血酸等常见干扰物质对测定的影响,用于生物样品分析,结果令人满意. 传感器用毕于4 ℃干态保存4周,其响应信号基本不变.

  2. Chemical Silver Coating of Fiber Tips in Near-Field Scanning Optical Microscopy

    Science.gov (United States)

    Vikram, Chandra S.; Witherow, William K.

    1998-01-01

    We report what is believed to be the first experimental demonstration of silver coating by a wet chemical process on tapered fiber tips used in near-field scanning optical microscopy. The process is at room temperature and pressure and takes only a few minutes to complete. Many tips can be simultaneously coated.

  3. A missense mutation in PMEL17 is associated with the Silver coat color in the horse

    Directory of Open Access Journals (Sweden)

    Cothran Gus

    2006-10-01

    Full Text Available Abstract Background The Silver coat color, also called Silver dapple, in the horse is characterized by dilution of the black pigment in the hair. This phenotype shows an autosomal dominant inheritance. The effect of the mutation is most visible in the long hairs of the mane and tail, which are diluted to a mixture of white and gray hairs. Herein we describe the identification of the responsible gene and a missense mutation associated with the Silver phenotype. Results Segregation data on the Silver locus (Z were obtained within one half-sib family that consisted of a heterozygous Silver colored stallion with 34 offspring and their 29 non-Silver dams. We typed 41 genetic markers well spread over the horse genome, including one single microsatellite marker (TKY284 close to the candidate gene PMEL17 on horse chromosome 6 (ECA6q23. Significant linkage was found between the Silver phenotype and TKY284 (θ = 0, z = 9.0. DNA sequencing of PMEL17 in Silver and non-Silver horses revealed a missense mutation in exon 11 changing the second amino acid in the cytoplasmic region from arginine to cysteine (Arg618Cys. This mutation showed complete association with the Silver phenotype across multiple horse breeds, and was not found among non-Silver horses with one clear exception; a chestnut colored individual that had several Silver offspring when mated to different non-Silver stallions also carried the exon 11 mutation. In total, 64 Silver horses from six breeds and 85 non-Silver horses from 14 breeds were tested for the exon 11 mutation. One additional mutation located in intron 9, only 759 bases from the missense mutation, also showed complete association with the Silver phenotype. However, as one could expect to find several non-causative mutations completely associated with the Silver mutation, we argue that the missense mutation is more likely to be causative. Conclusion The present study shows that PMEL17 causes the Silver coat color in the horse and

  4. Localized surface plasmon and exciton interaction in silver-coated cadmium sulphide quantum dots

    Science.gov (United States)

    Ghosh, P.; Rustagi, K. C.; Vasa, P.; Singh, B. P.

    2015-05-01

    Localized surface plasmon and exciton coupling has been investigated on colloidal solutions of silver-coated CdS nanoparticles (NPs), synthesized by gamma irradiation. Two broad photoluminescence (PL) bands (blue/red) corresponding to band to band and defect state transitions have been observed for the bare and coated samples. In case of bare CdS NPs, the intensity of the red PL peak is about ten times higher than the blue PL peak intensity. However, on coating the CdS NPs with silver, the peak intensity of the blue PL band gets enhanced and becomes equal to that of the red PL band. High-resolution transmission electron microscopic (HRTEM) images adequately demonstrate size distribution of these metal/semiconductor nanocomposites. UV-Vis absorption studies show quantum confinement effect in these semiconductor quantum dot (SQD) systems. Absorption spectrum of silver-coated SQDs shows signature of surface plasmon-exciton coupling which has been theoretically verified.

  5. An antibacterial coating based on a polymer/sol-gel hybrid matrix loaded with silver nanoparticles

    Directory of Open Access Journals (Sweden)

    Rivero Pedro

    2011-01-01

    Full Text Available Abstract In this work a novel antibacterial surface composed of an organic-inorganic hybrid matrix of tetraorthosilicate and a polyelectrolyte is presented. A precursor solution of tetraethoxysilane (TEOS and poly(acrylic acid sodium salt (PAA was prepared and subsequently thin films were fabricated by the dip-coating technique using glass slides as substrates. This hybrid matrix coating is further loaded with silver nanoparticles using an in situ synthesis route. The morphology and composition of the coatings have been studied using UV-VIS spectroscopy and atomic force microscopy (AFM. Energy dispersive X-ray (EDX was also used to confirm the presence of the resulting silver nanoparticles within the thin films. Finally the coatings have been tested in bacterial cultures of genus Lactobacillus plantarum to observe their antibacterial properties. It has been experimentally demonstrated that these silver loaded organic-inorganic hybrid films have a very good antimicrobial behavior against this type of bacteria.

  6. Localized surface plasmon and exciton interaction in silver-coated cadmium sulphide quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, P.; Rustagi, K. C.; Vasa, P.; Singh, B. P., E-mail: bhanuprs@gmail.com [Department of Physics, Indian Institute of Technology Bombay, Mumbai- 400076 (India)

    2015-05-15

    Localized surface plasmon and exciton coupling has been investigated on colloidal solutions of silver-coated CdS nanoparticles (NPs), synthesized by gamma irradiation. Two broad photoluminescence (PL) bands (blue/red) corresponding to band to band and defect state transitions have been observed for the bare and coated samples. In case of bare CdS NPs, the intensity of the red PL peak is about ten times higher than the blue PL peak intensity. However, on coating the CdS NPs with silver, the peak intensity of the blue PL band gets enhanced and becomes equal to that of the red PL band. High-resolution transmission electron microscopic (HRTEM) images adequately demonstrate size distribution of these metal/semiconductor nanocomposites. UV-Vis absorption studies show quantum confinement effect in these semiconductor quantum dot (SQD) systems. Absorption spectrum of silver-coated SQDs shows signature of surface plasmon-exciton coupling which has been theoretically verified.

  7. An antibacterial coating based on a polymer/sol-gel hybrid matrix loaded with silver nanoparticles

    Science.gov (United States)

    Rivero, Pedro José; Urrutia, Aitor; Goicoechea, Javier; Zamarreño, Carlos Ruiz; Arregui, Francisco Javier; Matías, Ignacio Raúl

    2011-12-01

    In this work a novel antibacterial surface composed of an organic-inorganic hybrid matrix of tetraorthosilicate and a polyelectrolyte is presented. A precursor solution of tetraethoxysilane (TEOS) and poly(acrylic acid sodium salt) (PAA) was prepared and subsequently thin films were fabricated by the dip-coating technique using glass slides as substrates. This hybrid matrix coating is further loaded with silver nanoparticles using an in situ synthesis route. The morphology and composition of the coatings have been studied using UV-VIS spectroscopy and atomic force microscopy (AFM). Energy dispersive X-ray (EDX) was also used to confirm the presence of the resulting silver nanoparticles within the thin films. Finally the coatings have been tested in bacterial cultures of genus Lactobacillus plantarum to observe their antibacterial properties. It has been experimentally demonstrated that these silver loaded organic-inorganic hybrid films have a very good antimicrobial behavior against this type of bacteria.

  8. Toxicogenomic responses of nanotoxicity in Daphnia magna exposed to silver nitrate and coated silver nanoparticles

    Science.gov (United States)

    Applications for silver nanomaterials in consumer products are rapidly expanding, creating an urgent need for toxicological examination of the exposure potential and ecological effects of silver nanoparticles (AgNPs). The integration of genomic techniques into environmental toxic...

  9. Silver-doped hydroxyapatite coatings formed on Ti–6Al–4V substrates and their characterization

    Energy Technology Data Exchange (ETDEWEB)

    Yanovska, A.A., E-mail: biophy@yandex.ru [Institute of Applied Physics National Academy of Sciences of Ukraine, 58, Sumy 40000 (Ukraine); Stanislavov, A.S. [Institute of Applied Physics National Academy of Sciences of Ukraine, 58, Sumy 40000 (Ukraine); Sukhodub, L.B. [Institute of Microbiology and Immunology, National Academy of Medical Sciences of Ukraine, 14-Puschinskaya St., Kharkov 61057 (Ukraine); Kuznetsov, V.N.; Illiashenko, V.Yu.; Danilchenko, S.N. [Institute of Applied Physics National Academy of Sciences of Ukraine, 58, Sumy 40000 (Ukraine); Sukhodub, L.F. [Sumy State University, Medical Institute, Ministry of Education and Science of Ukraine, R. Korsakova Str. 2, Sumy 40007 (Ukraine)

    2014-03-01

    Coatings with antibacterial components for medical implants are recommended to reduce the risk of bacterial infections. Therefore hydroxyapatite (HA) coatings with addition of chitosan (CS) and silver (Ag) are proposed in this work in an attempt to resolve this problem. Ti–6Al–4V substrates were modified by a chitosan film to study the influence of surface modification on the formation of the HA–Ag and HA–CS–Ag coatings. Using a thermal substrate method, HA and HA–CS coatings doped with Ag{sup +} were prepared at low substrate temperatures (90 °C). Coated surfaces were examined using X-ray diffraction and scanning electron microscopy. The amount of silver in the deposited coatings was analyzed by atomic absorption spectroscopy. From this study it is concluded that the substrate surface modified by a chitosan film promotes the coating formation and increases the antibacterial activity of produced coatings against a strain of Escherichia coli. The adhesion of E. coli (ATCC 25922) to sheep erythrocytes was decreased by 14% as compared with the reference samples without Ag. It could be explained by the inhibition of bacterial adhesins by Ag{sup +} ions released. The combined action of silver ions and chitosan resulted in a 21% decrease in adhesive index. - Highlights: • Silver doped hydroxyapatite (HA) coatings are deposited by thermal substrate method. • Surface modification of Ti–6Al–4V substrates by chitosan film is proposed. • The influence of surface modification on HA–Ag coating formation is investigated. • Substrates modified by a chitosan film promote the nucleation of the HA coatings. • Antibacterial effect on the E. coli is more expressed for coatings on modified surface.

  10. Fabrication and electromagnetic interference shielding effectiveness of polymeric composites filled with silver-coated microorganism cells

    Energy Technology Data Exchange (ETDEWEB)

    Lan, Mingming, E-mail: lan_mingming@163.com [College of Mechanical and Electrical Engineering, Henan Agricultural University, Zhengzhou 450002 (China); Zhang, Deyuan; Cai, Jun; Hu, Yanyan; Yuan, Liming [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, School of Mechanical Engineering and Automation, Beihang University, Beijing 100191 (China)

    2014-07-01

    In this paper, helical silver-coated Spirulina cells were used as conductive fillers for the fabrication of polymeric composites. The morphology and composition of the coated Spirulina cells were analyzed with scanning electron microscope and energy dispersive X-ray spectrometer. The densities of silver-coated Spirulina cells were measured using the standard Archimedes method with distilled water. The electrical resistivity was measured by four-probe technique using ammeter and voltmeter whereas electromagnetic interference shielding effectiveness was measured by four-port method using vector network analyzer and coaxial-airline sample holder. The results showed that the silver-coated Spirulina cells with different coating thickness were lightweight fillers compared to the other typical conductive particles. The polymeric composites could achieve good conductivity at the lower content of silver-coated Spirulina cells owing to their helical shape. The shielding effectiveness of polymeric composites had a strong dependence on their conductivity. At the coating thickness of 0.96 μm and the content of 40 vol%, the shielding effectiveness could reach above 74.3 dB in entire test wave band.

  11. Non-cytotoxic antibacterial silver-coumarin complex doped sol-gel coatings.

    Science.gov (United States)

    Jaiswal, Swarna; Bhattacharya, Kunal; Sullivan, Maeve; Walsh, Maureen; Creaven, Bernadette S; Laffir, Fathima; Duffy, Brendan; McHale, Patrick

    2013-02-01

    Microbial colonisation on clinical and industrial surfaces is currently of global concern and silane based sol-gel coatings are being proposed as potential solutions. Sol-gels are chemically inert, stable and homogeneous and can be designed to act as a reservoir for releasing antimicrobial agents over extended time periods. In the present study, silver nitrate (AgN) and a series of silver coumarin complexes based on coumarin-3-carboxylatosilver (AgC) and it is 6, 7 and 8 hydroxylated analogues (Ag6, Ag7, Ag8) were incorporated into sol-gel coatings. The comparative antibacterial activity of the coatings was determined against meticillin resistant Staphylococcus aureus (MRSA) and multidrug resistance Enterobacter cloacae WT6. The percentage growth inhibitions were found in the range of 9.2 (±2.7)-66.0 (±1.2)% at low silver loadings of 0.3% (w/w) with E. cloacae being the more susceptible. Results showed that among the Ag coumarin complexes, the Ag8 doped coating had the highest antibiofilm property. XPS confirmed the presence of silver in the nanoparticulate state (Ag(0)) at the coating surface where it remained after 4 days of exposure to bacterial culture. Comparative cytotoxicity studies revealed that the Ag-complex coatings were less toxic than the AgN coating. Thus, it can be concluded that a sol-gel matrix with Ag-coumarin complexes may provide non-toxic surfaces with antibacterial properties.

  12. Scalable Coating and Properties of Transparent, Flexible, Silver Nanowire Electrodes

    KAUST Repository

    Hu, Liangbing

    2010-05-25

    We report a comprehensive study of transparent and conductive silver nanowire (Ag NW) electrodes, including a scalable fabrication process, morphologies, and optical, mechanical adhesion, and flexibility properties, and various routes to improve the performance. We utilized a synthesis specifically designed for long and thin wires for improved performance in terms of sheet resistance and optical transmittance. Twenty Ω/sq and ∼ 80% specular transmittance, and 8 ohms/sq and 80% diffusive transmittance in the visible range are achieved, which fall in the same range as the best indium tin oxide (ITO) samples on plastic substrates for flexible electronics and solar cells. The Ag NW electrodes show optical transparencies superior to ITO for near-infrared wavelengths (2-fold higher transmission). Owing to light scattering effects, the Ag NW network has the largest difference between diffusive transmittance and specular transmittance when compared with ITO and carbon nanotube electrodes, a property which could greatly enhance solar cell performance. A mechanical study shows that Ag NW electrodes on flexible substrates show excellent robustness when subjected to bending. We also study the electrical conductance of Ag nanowires and their junctions and report a facile electrochemical method for a Au coating to reduce the wire-to-wire junction resistance for better overall film conductance. Simple mechanical pressing was also found to increase the NW film conductance due to the reduction of junction resistance. The overall properties of transparent Ag NW electrodes meet the requirements of transparent electrodes for many applications and could be an immediate ITO replacement for flexible electronics and solar cells. © 2010 American Chemical Society.

  13. Prevention of Staphylococcus epidermidis biofilm formation using a low-temperature processed silver-doped phenyltriethoxysilane sol-gel coating.

    Science.gov (United States)

    Stobie, Niall; Duffy, Brendan; McCormack, Declan E; Colreavy, John; Hidalgo, Martha; McHale, Patrick; Hinder, Steven J

    2008-03-01

    Sol-gel coatings which elute bioactive silver ions are presented as a potential solution to the problem of biofilm formation on indwelling surfaces. There is evidence that high-temperature processing of such materials can lead to diffusion of silver away from the coating surface, reducing the amount of available silver. In this study, we report the biofilm inhibition of a Staphylococcus epidermidis biofilm using a low-temperature processed silver-doped phenyltriethoxysilane sol-gel coating. The incorporation of a silver salt into a sol-gel matrix resulted in an initial high release of silver in de-ionised water and physiological buffered saline (PBS), followed by a lower sustained release for at least 6 days-as determined by graphite furnace-atomic absorption spectroscopy (GF-AAS). The release of silver ions from the sol-gel coating reduced the adhesion and prevented formation of a S. epidermidis biofilm over a 10-day period. The presence of surface silver before and after 24 h immersion in PBS was confirmed by X-ray photoelectron spectroscopy (XPS). These silver-doped coatings also exhibited significant antibacterial activity against planktonic S. epidermidis. A simple test to visualise the antibacterial effect of silver release coatings on neighbouring bacterial cultures is also reported.

  14. A Facile Synthesis of Silver-Coated Composite Particles by Swelling Surface Method

    Institute of Scientific and Technical Information of China (English)

    LIU Jun-Bing; LI Neng; WANG Si-Zhen; ZHANG Jian-Hui; WANG Zhen-Lin

    2005-01-01

    @@ We report a facile and rapid method for fabrication of composite particles consisting of a polystyrene (PS) core and a uniform silver shell.The process involves the PS colloid surface swelling, the anchoring of silver ions and nanoparticles onto the surfaces, and the subsequent growth of metal seeds in a short period.The present approach has the advantages of simplicity and high efficiency.The TEM images show the morphology of the obtained PS core-silver shell particles, and their chemical composition and crystallinity are analysed by x-ray diffraction.To our knowledge, this is the first study based on swelling PS surface for synthesis of silver-coated PS particles and may be implemented for preparing other metal-coated PS particles.

  15. Preparation of superhydrophobic silver nano coatings with feather-like structures by electroless galvanic deposition

    Institute of Scientific and Technical Information of China (English)

    FENG XiaoJuan; SHI YanLong; WANG YongSheng; YUE GuoRen; YANG Wu

    2013-01-01

    Superhydrophobic silver nanocoatings with feather-like morphology are fabricated on copper substrates by electroless galvanic deposition.The coating exhibit superhydrophobicity with a contact angle of 156.4° and glide angle of 4° without any further surface modification.Scanning electron microscope (SEM),X-ray diffraction (XRD) and contact angle measurements are used to investigate the morphology,crystal structure and superhydrophobicity,respectively,of the coatings.The coatings exhibit high thermal stability; their water contact angle did not change when the coatings were heated to 200℃ for 2 h.The mechanism of superhydrophobicity of the silver coating is discussed based on the work of Amirfazli,Wenzel and Cassie.

  16. Development of silver coating options for the Gemini 8-m telescopes project

    Science.gov (United States)

    Jacobson, Michael R.; Kneale, Ruth C.; Gillett, Fred C.; Raybould, Keith; Filhaber, John M.; Carniglia, Charles K.; Laird, Ronald; Kitchens, Dennis; Shimshock, Ric P.; Booth, Donald C.

    1998-08-01

    Acting as a prime contractor to the Gemini Project, the Optical Data Associates (ODA), with its major subcontractors, BOC Coating Technologies (BOCCT) and Deposition Sciences, Inc. (DSI), developed options for depositing protected silver coatings on the 8-M primary mirrors. The project began with a study that identified sputtering as the preferred deposition technique, defined a set of candidate adhesor and protective coatings for the silver layer, and simulated stack performance. The next phase involved pilot magnetron sputtering studies by BOCCT and DSI of designs involving silicon nitride and hafnia, respectively. ODA also developed mid-IR reflectance standards at (lambda) equals 10.6 micrometers to control the silver coating measurements in the critical 8 - 12 micrometers atmospheric window. The study results were successful, with both BOCCT and DSI producing Ag coatings with R equals 0.9920 +/- 0.0001 and protected Ag coatings with R equals 0.9910 +/- 0.0001. The Gemini Project coating plants are designed to sputter bare and protected Al and Ag coatings.

  17. Synthesis of silver-incorporated hydroxyapatite nanocomposites for antimicrobial implant coatings

    Science.gov (United States)

    Liu, Xiangmei; Mou, Yanan; Wu, Shuilin; Man, H. C.

    2013-05-01

    Because of excellent osteoconductivity and resorbability, hydroxyapatite (HA) is commonly used as a bone substitute material or implant coating. Both ionic and metallic silver are considered to have a broad spectrum of antimicrobial properties especially associated with biomaterial-related infections. The present work proposes a facile chemical reduction method to synthesize an Ag incorporated HA nanocomposite. Ammoniacal silver solution was firstly prepared and then added into the HA solution, followed by hydrazine hydrate (N2H4·H2O) being used to reduce the silver ions to metallic silver. The formed Ag nanoparticles had diameters of 20-30 nm and were firmly attached on the HA particle surfaces. This approach can also keep the integrity of the HA chemical structure and the morphology. The strain Escherichia coli was used to evaluate the antibacterial effect of the nanocomposite. An In vitro bacterial adhesion study indicated a significant enhancement in the antibacterial property of silver containing HA.

  18. NANO-STRUCTURED SILVER COATING ON COPPER PREPARED IN AN ETHANOL-BASED SOLUTION

    Institute of Scientific and Technical Information of China (English)

    Zheliang Wei; Dian Tang; Thomas O'Keefe

    2005-01-01

    Recently, silver as an electrochemical deposit on copper substrate has been attracting much attention in the microelectronics field. To deposit nano-scale silver particles on copper, immersion plating using cyanide-based baths is commonly used. In this study, non-toxic ethanol was used as the plating solution. Sputtered copper samples were terized by a field emission scanning electron microscope (FE-SEM), an energy dispersive X-ray spectroscope (EDS),and an atomic force microscope (AFM). It was found that the deposited particles are metallic silver. After 3 s immersion,fine particles whose diameters were around 6 nm had covered about 40% of the surface of the copper substrate. After10 s immersion, the copper surface was completely covered by silver particles, the diameters of which have increased to about 10-15 nm. After the whole surface was covered, a dense and smooth silver coating was obtained.

  19. Physicochemical Analysis of the Polydimethylsiloxane Interlayer Influence on a Hydroxyapatite Doped with Silver Coating

    Directory of Open Access Journals (Sweden)

    C. L. Popa

    2015-01-01

    Full Text Available We investigate by different complementary methods the processes occurring when a polydimethylsiloxane film is used as interlayer for a silver doped hydroxyapatite coating. The X-ray diffraction and Fourier Transform Infrared Spectroscopy measurements show that the hydroxyapatite doped with silver is in a crystalline form and some SiO44- ions formation takes place at the surface and in the bulk of the new hydroxyapatite doped with silver/polydimethylsiloxane composite layer. The possibility of SiO44- ions incorporation in the structure of silver doped hydroxyapatite by the mechanism of SiO44-/PO43- ions substitution is analysed. The new formed silver doped hydroxyapatite/polydimethylsiloxane composite layer is compact, homogeneous, with no cracks as it was shown by Scanning Electron Microscopy and Glow Discharge Optical Emission Spectrometry.

  20. Pulsed laser deposition of antimicrobial silver coating on Ormocer (registered) microneedles

    Energy Technology Data Exchange (ETDEWEB)

    Gittard, S D; Narayan, R J; Jin, C; Monteiro-Riviere, N A [Joint Department of Biomedical Engineering, North Carolina State University, Raleigh, NC 27695 (United States); Ovsianikov, A; Chichkov, B N [Laser Zentrum Hannover, Hollerithallee 8, 30419 Hannover (Germany); Stafslien, S; Chisholm, B, E-mail: roger_narayan@msn.co [Center for Nanoscale Science and Engineering, North Dakota State University, 1805 Research Park Drive, Fargo, ND 58102 (United States)

    2009-12-15

    One promising option for transdermal delivery of protein- and nucleic acid-based pharmacologic agents involves the use of microneedles. However, microneedle-generated pores may allow microorganisms to penetrate the stratum corneum layer of the epidermis and cause local or systemic infection. In this study, microneedles with antimicrobial functionality were fabricated using two-photon polymerization-micromolding and pulsed laser deposition. The antibacterial activity of the silver-coated organically modified ceramic (Ormocer (registered) ) microneedles was demonstrated using an agar diffusion assay. Human epidermal keratinocyte viability on the Ormocer (registered) surfaces coated with silver was similar to that on uncoated Ormocer (registered) surfaces. This study indicates that coating microneedles with silver thin films using pulsed laser deposition is a useful and novel approach for creating microneedles with antimicrobial functionality. (communication)

  1. Long-term active antimicrobial coatings for surgical sutures based on silver nanoparticles and hyperbranched polylysine.

    Science.gov (United States)

    Ho, Chau Hon; Odermatt, Erich K; Berndt, Ingo; Tiller, Joerg C

    2013-01-01

    The goal of this study was to develop a long-term active antimicrobial coating for surgical sutures. To this end, two water-insoluble polymeric nanocontainers based on hyperbranched polylysine (HPL), hydrophobically modified by either using glycidyl hexadecyl ether, or a mixture of stearoyl/palmitoyl chloride, were synthesized. Highly stabilized silver nanoparticles (AgNPs, 2-5 nm in size) were generated by dissolving silver nitrate in the modified HPL solutions in toluene followed by reduction with L-ascorbic acid. Poly(glycolic acid)-based surgical sutures were dip-coated with the two different polymeric silver nanocomposites. The coated sutures showed high efficacies of more than 99.5% reduction of adhesion of living Staphylococcus aureus cells onto the surface compared to the uncoated specimen. Silver release experiments were performed on the HPL-AgNP modified sutures by washing them in phosphate buffered saline for a period of 30 days. These coatings showed a constant release of silver ions over more than 30 days. After this period of washing, the sutures retained their high efficacies against bacterial adhesion. Cytotoxicity tests using L929 mouse fibroblast cells showed that the materials are basically non-cytotoxic.

  2. The relationship between the antimicrobial effect of catheter coatings containing silver nanoparticles and the coagulation of contacting blood.

    Science.gov (United States)

    Stevens, Kris N J; Crespo-Biel, Olga; van den Bosch, Edith E M; Dias, Aylvin A; Knetsch, Menno L W; Aldenhoff, Yvette B J; van der Veen, Frederik H; Maessen, Jos G; Stobberingh, Ellen E; Koole, Leo H

    2009-08-01

    It is well known that surface coatings for medical devices can be made antimicrobial through introduction of silver nanoparticles. By virtue of their extremely large surface-to-volume ratio, the silver particles serve as a depot for sustained release of silver ions, despite the fact that silver is not readily oxidized. Antimicrobial coatings are especially important in connection with indwelling catheters with a high risk of bacterial line infections, such as central venous catheters (CVCs). This study specifically addressed the question what the impact of silver nanoparticles (exposed at the coating's surface) and/or the release of silver ions would be on coagulation of contacting blood. Studies, performed in vitro with fresh platelet-rich blood plasma (PRP) from 5 different healthy volunteer donors, clearly pointed out that: (i) the presence of silver nanoparticles correlates with accelerated thrombin formation upon contact of the coating with PRP; (ii) platelet activation is stronger as a result from the contact with silver nanoparticle-containing coatings as compared to other coatings which are devoid of silver. A series of titration experiments, in which the potential effect of silver ions is mimicked, revealed that the observed activation of blood platelets can be best explained through a collision mechanism. The results suggest that platelets that collide with silver, exposed at the surface, become activated without adhering to the surface. These new results point, rather unexpectedly, at a double effect of the silver nanoparticles in the coating: a strong antimicrobial effect occurs simultaneously with acceleration of the coagulation of contacting blood. This new information is, evidently, most relevant for the development of improved surface coatings for indwelling catheters (such as CVCs) which should combine antimicrobial features and close-to-zero thrombogenicity.

  3. Mechanical, In Vitro Antimicrobial and Biological Properties of Plasma Sprayed Silver-Doped Hydroxyapatite Coating

    OpenAIRE

    Roy, Mangal; Fielding, Gary A.; BEYENAL, Haluk; Bandyopadhyay, Amit; Bose, Susmita

    2012-01-01

    Implant related infection is one of the key concerns in total joint hip arthroplasties. In order to reduce bacterial adhesion, silver (Ag) / silver oxide (Ag2O) doping was used in plasma sprayed hydroxyapatite (HA) coating on titanium substrate. HA powder was doped with 2.0, 4.0 and 6.0 wt% Ag, heat treated at 800 °C and used for plasma spray coating using a 30 kW plasma spray system, equipped with supersonic nozzle. Application of supersonic plasma nozzle significantly reduced phase decompos...

  4. Preparation of amine coated silver nanoparticles using triethylenetetramine

    Indian Academy of Sciences (India)

    L Ramajo; R Parra; M Reboredo; M Castro

    2009-01-01

    This article presents a simple method towards the preparation of functionalized silver nanoparticles in a continuous medium. Silver nanoparticles were obtained through AgNO3 chemical reduction in ethanol and triethylenetetramine was used to stabilize and functionalize the metal. The product was characterized with X-ray diffraction (XRD), Fourier-transformed infrared spectroscopy (FTIR), UVvisible spectroscopy, thermal gravimetric analysis (TGA) and transmission electron microscopy (TEM). Monocrystalline silver particles with cubic structure and an average size of 20 nm were obtained. The results reveal that it is possible to synthesize Ag nanoparticles functionalized with amine groups and that particle size is influenced by the processing route.

  5. Mechanically stable antimicrobial chitosan-PVA-silver nanocomposite coatings deposited on titanium implants.

    Science.gov (United States)

    Mishra, Sandeep K; Ferreira, J M F; Kannan, S

    2015-05-05

    Bionanocomposite coatings with antimicrobial activity comprising polyvinyl alcohol (PVA)-capped silver nanoparticles embedded in chitosan (CS) matrix were developed by a green soft chemistry synthesis route. Colloidal sols of PVA-capped silver nanoparticles (AgNPs) were synthesized by microwave irradiating an aqueous solution comprising silver nitrate and PVA. The bionanocomposites were prepared by adding an aqueous solution of chitosan to the synthesized PVA-capped AgNPs sols in appropriate ratios. Uniform bionanocomposite coatings with different contents of PVA-capped AgNPs were deposited onto titanium substrates by "spread casting" followed by solvent evaporation. Nanoindentation and antimicrobial activity tests performed on CS and bionanocomposites revealed that the incorporation of PVA-capped AgNPs enhanced the overall functional properties of the coatings, namely their mechanical stability and bactericidal activity against Escherichia coli and Staphylococcus aureus. The coated specimens maintained their antimicrobial activity for 8h due to the slow sustained release of silver ions. The overall benefits for the relevant functional properties of the coatings were shown increase with increasing contents of PVA-capped AgNPs in the bionanocomposites.

  6. Preparation and characterization of chitosan-silver/hydroxyapatite composite coatings onTiO{sub 2} nanotube for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Yajing [Institute of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu 610054 (China); Zhang, Xuejiao [Medical Informatics, Hebei North University, Zhangjiakou 075000 (China); Li, Caixia [Institute of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu 610054 (China); Huang, Yong [Institute of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu 610054 (China); College of Lab Medicine, Hebei North University, Zhangjiakou 075000 (China); Ding, Qiongqiong [Institute of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu 610054 (China); Pang, Xiaofeng, E-mail: xfpang@aliyun.com [Institute of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu 610054 (China)

    2015-03-30

    Highlights: • Chitosan/silver-doped hydroxyapatite biocomposite coating was successfully deposited on anodized Ti by electrochemical deposition. • The chemical state of silver in the synthesized coatings was studied by XPS peak deconvolution. • The synthesized coatings have excellent antibacterial activity because of synergistic effect of the Ag and CS. • The CSAgHAp coatings showed good biocompatibility and no adverse effect in cell culture tests. - Abstract: A biocomposite coating containing chitosan, silver, and hydroxyapatite was developed on anodized titanium substrate by electrochemical deposition. Coatings were characterized by field-emission scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and polarisation studies. Results showed that the prepared coatings had compact and dense morphology with a thickness of 6.2 ± 0.7 μm and that silver was evenly distributed. Testing the prepared coatings with Gram-positive and Gram-negative bacterial strains exhibited antibacterial activity because of the synergistic effect of silver and chitosan. The prepared coatings were also found to be nontoxic to MC3T3-E1 cells. These results suggested that chitosan/silver-hydroxyapatite biocomposite coatings can prevent the bacterial infection of implants.

  7. Silver nanocluster/silica composite coatings obtained by sputtering for antibacterial applications

    Science.gov (United States)

    Ferraris, M.; Balagna, C.; Perero, S.; Miola, M.; Ferraris, S.; Baino, F.; Battiato, A.; Manfredotti, C.; Vittone, E.; Vernè, E.

    2012-09-01

    Silver nanocluster silica composite coatings were deposited by radio frequency co-sputtering technique on several substrates. This versatile method allows tailoring of silver content and antibacterial behaviour of coatings deposited on glasses, ceramics, metals and polymers for several applications. Coating morphology and composition as well as nanocluster size were analyzed by means of UV-Visible absorption, X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), electron dispersive spectroscopy (EDS), X-ray Photoelectron Spectroscopy (XPS) and Atomic Force Microscopy (AFM). The antibacterial effect was verified through the inhibition halo test against standard bacterial strain, Staphylococcus aureus, before and after sterilization process. Tape test demonstrated a good adhesion of the coatings to the substrates.

  8. Electrodeposition, characterization, and antibacterial activity of zinc/silver particle composite coatings

    Energy Technology Data Exchange (ETDEWEB)

    Reyes-Vidal, Y.; Suarez-Rojas, R.; Ruiz, C.; Torres, J. [Center of Research and Technological Development in Electrochemistry (CIDETEQ), Parque Tecnológico Sanfandila, Pedro Escobedo, Querétaro, A.P.064, C.P.76703, Querétaro (Mexico); Ţălu, Ştefan [Technical University of Cluj-Napoca, Faculty of Mechanical Engineering, Department of AET, Discipline of Descriptive Geometry and Engineering Graphics, 103-105 B-dul Muncii St., Cluj-Napoca 400641 Cluj (Romania); Méndez, Alia [Centro de Química-ICUAP Benemérita Universidad Autónoma de Puebla, Ciudad Universitaria Puebla, 72530 Puebla (Mexico); Trejo, G., E-mail: gtrejo@cideteq.mx [Center of Research and Technological Development in Electrochemistry (CIDETEQ), Parque Tecnológico Sanfandila, Pedro Escobedo, Querétaro, A.P.064, C.P.76703, Querétaro (Mexico)

    2015-07-01

    Highlights: • Zn/AgPs composites coatings were formed for electrodeposition. • CTAB promotes occlusion of silver particles in the coating. • Zn/AgPs coatings present very good antibacterial activity. - Abstract: Composite coatings consisting of zinc and silver particles (Zn/AgPs) with antibacterial activity were prepared using an electrodeposition technique. The morphology, composition, and structure of the Zn/AgPs composite coatings were analyzed using scanning electron microscopy (SEM) coupled with energy-dispersive spectroscopy (EDS), inductively coupled plasma (ICP) spectrometry, and X-ray diffraction (XRD). The antibacterial properties of the coatings against the microorganisms Escherichia coli as a model Gram-negative bacterium and Staphylococcus aureus as a model Gram-positive bacterium were studied quantitatively and qualitatively. The results revealed that the dispersant cetyltrimethylammonium bromide (CTAB) assisted in the formation of a stable suspension of Ag particles in the electrolytic bath for 24 h. Likewise, a high concentration of CTAB in the electrolytic bath promoted an increase in the number of Ag particles occluded in the Zn/AgPs coatings. The Zn/AgPs coatings that were obtained were compact, smooth, and shiny materials. Antimicrobial tests performed on the Zn/AgPs coatings revealed that the inhibition of bacterial growth after 30 min of contact time was between 91% and 98% when the AgPs content ranged from 4.3 to 14.0 mg cm{sup −3}.

  9. Adhesion of E. coli to silver- or copper-coated porous clay ceramic surfaces

    Science.gov (United States)

    Yakub, I.; Soboyejo, W. O.

    2012-06-01

    Porous ceramic water filters (CWFs), produced by sintering a mixture of clay and a combustible material (such as woodchips), are often used in point-of-use water filtration systems that occlude microbes by size exclusion. They are also coated with colloidal silver, which serves as a microbial disinfectant. However, the adhesion of microbes to porous clay surfaces and colloidal silver coated clay surfaces has not been studied. This paper presents the results of atomic force microscopy (AFM) measurements of the adhesion force between Escherichia coli bacteria, colloidal silver, and porous clay-based ceramic surfaces. The adhesion of silver and copper nanoparticles is also studied in control experiments on these alternative disinfectant materials. The adhesive force between the wide range of possible bi-materials was measured using pull-off measurements during force microscopy. These were combined with measurements of AFM tip radii/substrate roughness that were incorporated into adhesion models to obtain the adhesion energies for the pair wise interaction. Of the three antimicrobial metals studied, the colloidal silver had the highest affinity for porous ceramic surface (125 ± 32 nN and ˜0.29 J/m2) while the silver nanoparticles had the highest affinity for E. coli bacteria (133 ± 21 nN and ˜0.39 J/m2). The implications of the results are then discussed for the design of ceramic water filter that can purify water by adsorption and size exclusion.

  10. Antimicrobial activity and cytotoxicity of cotton fabric coated with conducting polymers, polyaniline or polypyrrole, and with deposited silver nanoparticles

    Science.gov (United States)

    Maráková, Nela; Humpolíček, Petr; Kašpárková, Věra; Capáková, Zdenka; Martinková, Lenka; Bober, Patrycja; Trchová, Miroslava; Stejskal, Jaroslav

    2017-02-01

    Cotton fabric was coated with conducting polymers, polyaniline or polypyrrole, in situ during the oxidation of respective monomers. Raman and FTIR spectra proved the complete coating of substrates. Polypyrrole content was 19.3 wt.% and that of polyaniline 6.0 wt.%. Silver nanoparticles were deposited from silver nitrate solutions of various concentrations by exploiting the reduction ability of conducting polymers. The content of silver was up to 11 wt.% on polypyrrole and 4 wt.% on polyaniline. The sheet resistivity of fabrics was determined. The conductivity was reduced after deposition of silver. The chemical cleaning reduced the conductivity by less than one order of magnitude for polypyrrole coating, while for polyaniline the decrease was more pronounced. The good antibacterial activity against S. aureus and E. coli and low cytotoxicity of polypyrrole-coated cotton, both with and without deposited silver nanoparticles

  11. Stabilization of 2D assemblies of silver nanoparticles by spin-coating polymers

    Science.gov (United States)

    Hu, Longyu; Pfirman, Aubrie; Chumanov, George

    2015-12-01

    Silver nanoparticles self-assembled on poly(4-vinylpyridine) modified surfaces were spin-coated with poly(methyl methacrylate), poly(butyl methacrylate) and polystyrene from anisole and toluene solutions. The polymers filled the space between the particles thereby providing stabilization of the assemblies against particle aggregation when dried or chemically modified. The polymers did not coat the top surface of the nanoparticles offering the chemical accessibility to the metal surface. This was confirmed by converting the stabilized nanoparticles into silver sulfide and gold clusters. Etching the nanoparticles resulted in crater-like polymeric structures with the cavities extending down to the underlying substrate. Electrochemical reduction of silver inside the craters was performed. The approach can be extended to other nanoparticle assemblies and polymers.

  12. Antimicrobial activity of nanocomposite zirconium nitride/silver coatings to combat external bone fixation pin infections.

    Science.gov (United States)

    Wickens, David J; West, Glen; Kelly, Peter J; Verran, Joanna; Lynch, Stephen; Whitehead, Kathryn A

    2012-10-01

    During external fixation, temporary implants are used to penetrate the skin, muscle and bone to support severely fractured bones. This creates a biologically critical interface at the site of entry, which potentially allows a risk of infection. The aim of this study, therefore, was to investigate potential antimicrobial nanocomposites to combat infection. Magnetron sputtering was used to produce zirconium nitride/silver nanocomposite coatings, which were prepared at two different silver concentrations of 15.5 at.% and 29.8 at.%. These coatings were characterized for morphology, chemical composition, and antimicrobial activity in comparison to pure zirconium nitride and stainless steel. Staphylococcus aureus and Staphylococcus epidermidis were used as in vitro test organisms in a range of antimicrobial assays; retention of the bacteria on the surfaces and their survival using LiveDead™ staining; the use of a metabolic redox dye to indicate a contact kill and zone of inhibition assays to indicate leaching of inhibitory silver ions. Antimicrobial tests demonstrated a significant kill when the bacterial cells came in contact with the coatings containing silver at both 15.5 at.% and 29.8 at.%. No inhibitory leaching from the surfaces occurred. These surfaces demonstrate potential for use as antimicrobial fixation pin coatings.

  13. CHEMICALLY DEPOSITED SILVER FILM USED AS A SERS-ACTIVE OVER COATING LAYER FOR POLYMER FILM

    Institute of Scientific and Technical Information of China (English)

    Xiao-ning Liu; Gi Xue; Yun Lu; Jun Zhang; Fen-ting Li; Chen-chen Xue; Stephen Z.D. Cheng

    2001-01-01

    When colloidal silver particles were chemically deposited onto polymer film as an over-coating layer, surfaceenhanced Raman scattering (SERS) spectra could be collected for the surface analysis. SERS measurements of liquid crystal film were successfully performed without disturbing the surface morphology.

  14. Progress in UCO's search for silver-based telescope mirror coatings

    Science.gov (United States)

    Phillips, Andrew C.; Miller, Joseph S.; Bolte, Michael; DuPraw, Brian; Radovan, Matthew; Cowley, David

    2012-09-01

    We report on the on-going effort at University of California Observatories Astronomical Coatings Lab to develop robust protected-silver coatings suitable for telescope mirrors. We have identified a very promising recipe based on YF3 that produces excellent reflectivity at wavelengths of 340 nm and greater, has ~1.5% emissivity in the thermal IR, and does not contain problematic materials for the Mid-IR, such as SiO2 and Al2O3. The recipe holds up extremely well to aggressive environmental testing (80C and 80% RH; high-H2S atmosphere), and currently is being evaluated under real observatory conditions. This coating may satisfy the need for telescope mirror coatings that are long-lasting (~5 years or more) and have good reflectivity into the UV. We also evaluate and compare some other silver-based coatings developed elsewhere that should be useful in the same role. In addition, we describe recent upgrades to our coating facilities allowing us to deposit ion-assisted e-beam coatings on optics up to ~1m. This novel arrangement places the e-gun and ion source on a pivoting "swing-arm", allowing the position to move radially without changing the e-gun/ion source/ substrate geometry. Large substrates can be coated with good uniformity using single-axis rotation only. This technique is scalable to arbitrarily large substrate sizes.

  15. Employment of gold-coated silver nanowires as transparent conductive electrode for organic light emitting diodes

    Science.gov (United States)

    Kim, Sunho; Kim, Bongsung; Im, Inseob; Kim, Dongjae; Lee, Haeseong; Nam, Jaewook; Chung, Ho Kyoon; Lee, Hoo-Jeong; Cho, Sung Min

    2017-08-01

    This study proposes a simple method of Au coating on silver nanowires (Ag NWs) transparent conductive films as the anode of organic light emitting diodes (OLED) to increase the work function of the film and thus enhance hole transport. We carefully engineer the process conditions (pretreatment, solution concentrations, and coating number) of the coating using a diluted HAuCl4 solution on the Ag NWs film to minimize etching damage on Ag NWs accompanying the galvanic replacement reaction. Ultraviolet photoelectron spectroscopy and Kelvin probe force microscopy show work function increase of Ag NWs upon Au coating. OLED devices based on Au-coated Ag NWs show a lower turn-on voltage and higher luminance, compared with pristine Ag NWs device. Although the Ag NWs device displays poor efficiencies in the low luminance range due to a high leakage, some of the Au-coated Ag NWs devices showed efficiencies higher than those of the ITO device in a high luminance.

  16. Cytotoxicity Induced by Engineered Silver Nanocrystallites is Dependent on Surface Coatings and Cell Types

    Energy Technology Data Exchange (ETDEWEB)

    Suresh, Anil K [ORNL; Pelletier, Dale A [ORNL; Wang, Wei [ORNL; Morrell-Falvey, Jennifer L [ORNL; Doktycz, Mitchel John [ORNL

    2012-01-01

    Due to their unique antimicrobial properties silver nanocrystallites have garnered substantial recognition and are used extensively in biomedical applications such as wound dressing, surgical instruments and as bone substitute material. They are also released into unintended locations such as the environment or biosphere. Therefore it is imperative to understand the potential interactions, fate and transport of nanoparticles with environmental biotic systems. Although numerous factors including the composition, size, shape, surface charge and capping molecule of nanoparticles are known to influence the cell cytotoxicity, our results demonstrate for the first time that surface coatings are a major determinant in eliciting the potential cytotoxicity and cell interactions of silver nanoparticles. In the present investigation, silver nanocrystallites with nearly uniform size and shape distribution but with different surface coatings, imparting overall high negativity to high positivity, were synthesized. These nanoparticles were poly (diallyldimethylammonium) chloride-Ag, biogenic-Ag, colloidal-Ag (uncoated) and oleate-Ag with zeta potentials +45 5 mV, -12 2 mV, -42 5 mV and -45 5 mV respectively; the particles were thoroughly purified so as to avoid false cytotoxicity interpretations. A systematic investigation on the cytotoxic effects, cellular response and membrane damage caused by these four different silver nanoparticles were evaluated using multiple toxicity measurements on mouse macrophage (RAW-264.7) and lung epithelial (C-10) cell lines. From a toxicity perspective, our results clearly indicated that the cytotoxicity was depend on various factors such as synthesis procedure, surface coat or surface charge and the cell-type for the different silver nanoparticles that were investigated. Poly (diallyldimethylammonium) chloride -Ag was found to be the most toxic, followed by biogenic-Ag and oleate-Ag, whereas uncoated-Ag was found to be least toxic to both

  17. Silver ion doped ceramic nano-powder coated nails prevent infection in open fractures: In vivo study.

    Science.gov (United States)

    Kose, Nusret; Çaylak, Remzi; Pekşen, Ceren; Kiremitçi, Abdurrahman; Burukoglu, Dilek; Koparal, Savaş; Doğan, Aydın

    2016-02-01

    Despite improvement in operative techniques and antibiotic therapy, septic complications still occur in open fractures. We developed silver ion containing ceramic nano powder for implant coating to provide not only biocompatibility but also antibacterial activity to the orthopaedic implants. We hypothesised silver ion doped calcium phosphate based ceramic nano-powder coated titanium nails may prevents bacterial colonisation and infection in open fractures as compared with uncoated nails. 33 rabbits divided into three groups. In the first group uncoated, in the second group hydroxyapatite coated, and in the third group silver doped hydroxyapatite coated titanium nails were inserted left femurs of animals from knee regions with retrograde fashion. Before implantation of nails 50 μl solution containing 10(6)CFU/ml methicillin resistance Staphylococcus aureus (MRSA) injected intramedullary canal. Rabbits were monitored for 10 weeks. Blood was taken from rabbits before surgery and on 2nd, 6th and 10th weeks. Blood was analysed for biochemical parameters, blood count, C-reactive protein and silver levels. At the end of the 10 weeks animals were sacrificed and rods were extracted in a sterile fashion. Swab cultures were taken from intramedullary canal. Bacteria on titanium rods were counted. Liver, heart, spleen, kidney and central nervous tissues samples were taken for determining silver levels. Histopathological evaluation of bone surrounding implants was also performed. No significant difference was detected between the groups from hematologic, biochemical, and toxicological aspect. Microbiological results showed that less bacterial growth was detected with the use of silver doped ceramic coated implants compared to the other two groups (p=0.003). Accumulation of silver was not detected. No cellular inflammation was observed around the silver coated prostheses. No toxic effect of silver on bone cells was seen. Silver ion doped calcium phosphate based ceramic nano

  18. Silver activation on thin films of Ag-ZrCN coatings for antimicrobial activity.

    Science.gov (United States)

    Ferreri, I; Calderon V, S; Escobar Galindo, R; Palacio, C; Henriques, M; Piedade, A P; Carvalho, S

    2015-10-01

    Nowadays, with the increase of elderly population and related health problems, knee and hip joint prosthesis are being widely used worldwide. However, failure of these invasive devices occurs in a high percentage thus demanding the revision of the chirurgical procedure. Within the reasons of failure, microbial infections, either hospital or subsequently-acquired, contribute in high number to the statistics. Staphylococcus epidermidis (S. epidermidis) has emerged as one of the major nosocomial pathogens associated with these infections. Silver has a historic performance in medicine due to its potent antimicrobial activity, with a broad-spectrum on the activity of different types of microorganisms. Consequently, the main goal of this work was to produce Ag-ZrCN coatings with antimicrobial activity, for the surface modification of hip prostheses. Thin films of ZrCN with several silver concentrations were deposited onto stainless steel 316 L, by DC reactive magnetron sputtering, using two targets, Zr and Zr with silver pellets (Zr+Ag target), in an atmosphere containing Ar, C2H2 and N2. The antimicrobial activity of the modified surfaces was tested against S. epidermidis and the influence of an activation step of silver was assessed by testing samples after immersion in a 5% (w/v) NaClO solution for 5 min. The activation procedure revealed to be essential for the antimicrobial activity, as observed by the presence of an inhibition halo on the surface with 11 at.% of Ag. The morphology analysis of the surface before and after the activation procedure revealed differences in silver distribution indicating segregation/diffusion of the metallic element to the film's surface. Thus, the results indicate that the silver activation step is responsible for an antimicrobial effect of the coatings, due to silver oxidation and silver ion release.

  19. PVP-coated silver nanoparticles and silver ions induce reactive oxygen species, apoptosis and necrosis in THP-1 monocytes

    DEFF Research Database (Denmark)

    Foldbjerg, Rasmus; Olesen, Ping Liu; Hougaard, Mads

    2009-01-01

    the effect of well characterized, PVP-coated Ag NPs (69 nm ± 3 nm) and Ag+ in a human monocytic cell line (THP-1). Characterization of the Ag NPs was conducted in both stock suspension and cell media with or without serum and antibiotics. By using the flowcytometric annexin V/propidium iodide (PI) assay......The objective of the present study was to investigate the toxicity of silver nanoparticles (Ag NPs) in vitro. Silver ions (Ag+) have been used in medical treatments for decades whereas Ag NPs have been used in a variety of consumer products within recent years. This study was undertaken to compare......, both Ag NPs and Ag+ were shown to induce apoptosis and necrosis in THP-1 cells depending on dose and exposure time. Furthermore, the presence of apoptosis could be confirmed by the TUNEL method. A number of studies have implicated the production of reactive oxygen species (ROS) in cytotoxicity mediated...

  20. Silver-coated dacron prosthesis in the treatment of infection in arterial surgery: Case reports

    Directory of Open Access Journals (Sweden)

    Nenezić Dragoslav

    2008-01-01

    Full Text Available INTRODUCTION Although the incidence is low, infection of prosthetic vascular graft bears a high incidence of serious complications including 25-75% mortality rate and 40-75% limb loss. The standard treatment of vascular graft infection consists of excision of the prosthesis, wound debridement and extraanatomic revascularization. Conservative treatment might be an option in a limited number of patients. We present three cases of surgical and conservative treatment of vascular graft infection. CASE OUTLINE Case 1: A patient developed silver-coated graft infection after femorodistal arterial reconstruction performed because of critical limb ischemia. In the early postoperative period, massive skin and subcutaneous tissue necrosis developed, with the graft being exposed. After two months of persistent debridement and wound toilette, the defect was covered with a Thiersch skin graft. Case 2: PTFE graft infection in the right groin followed reconstruction of the isolated common femoral artery aneurysm. This graft was replaced with a silver-coated graft in situ. Reinfection of the proximal end of the implanted silver-coated graft occurred and the graft was exposed. After repeated debridement and wound toilette, the exposed prosthesis was covered with granulomatous tissue, and the wound healed. Case 3: A year after anastomotic pseudoaneurysm resection in the left groin, prosthesis was exposed following wound infection. This graft was substituted with a silver-coated graft in situ. The wound healed primarily. CONCLUSION These three cases demonstrate that under some circumstances vascular prosthesis infection can be successfully treated conservatively without graft removal, and also by in situ replacement using silver-coated graft.

  1. Improvement of transmission properties for a rugged polymer-coated silver hollow fiber

    Science.gov (United States)

    Iwai, Katsumasa; Takaku, Hiroyuki; Miyagi, Mitsunobu; Shi, Yi-Wei; Matsuura, Yuji

    2015-03-01

    An extremely rugged hollow fiber is fabricated by liquid-phase coating technique. A silica glass capillary is used as the substrate and vitreous film is firstly coated on the inner surface of the capillary to protect the glass tube from moisture. This protective coating keeps the thin-wall glass tube away from damage due to the following silver plating process. The additional transmission loss caused by the roughness of the protective film is decreased by limiting the length of the protective film. The whole length of 0.7-mm-bore hollow fiber was 1.2 m and the length of the rugged part which formed the protective film was only 30 cm. Transmission properties of the rugged polymer-coated silver hollow fibers for the Er:YAG laser and red pilot beam delivery have been improved. The loss for the 0.7-μm-bore size, 1.2-m-length rugged polymer-coated silver hollow fiber was 1 dB and 6.9 dB under straight condition, and 1.9 dB and 9.4 dB under the condition of a 270 degree bend with a 15-mm bending radius at the wavelength of 2.94 μm and 650 nm, respectively.

  2. Determination of acetylsalicylic acid in commercial tablets by SERS using silver nanoparticle-coated filter paper

    Science.gov (United States)

    Sallum, Loriz Francisco; Soares, Frederico Luis Felipe; Ardila, Jorge Armando; Carneiro, Renato Lajarim

    2014-12-01

    In this work, filter paper was used as a low cost substrate for silver nanoparticles in order to perform the detection and quantification of acetylsalicylic acid by SERS in a commercial tablet. The reaction conditions were 150 mM of ammonium hydroxide, 50 mM of silver nitrate, 500 mM of glucose, 12 min of the reaction time, 45 °C temperature, pretreatment with ammonium hydroxide and quantitative filter paper (1-2 μm). The average size of silver nanoparticles deposited on the paper substrate was 180 nm. Adsorption time of acetylsalicylic acid on the surface of the silver-coated filter paper was studied and an adsorption time of 80 min was used to build the analytical curve. It was possible to obtain a calibration curve with good precision with a coefficient of determination of 0.933. The method proposed in this work was capable to quantify acetylsalicylic acid in commercial tablets, at low concentration levels, with relative error of 2.06% compared to the HPLC. The preparation of filter paper coated with silver nanoparticles using Tollen's reagent presents several advantages such as low cost of synthesis, support and reagents; minimum amount of residuals, which are easily treated, despite the SERS spectroscopy presenting fast analysis, with low sample preparation and low amount of reactants as in HPLC analysis.

  3. Preparation of silver-chitosan nanocomposites and coating on bandage for antibacterial wound dressing application

    Energy Technology Data Exchange (ETDEWEB)

    Susilowati, Endang, E-mail: endwati@yahoo.co.id; Ashadi [Chemistry Education Department, Faculty of Teacher Training and Education, Universitas Sebelas Maret Surakarta (Indonesia); Maryani [Medical Doctor Program, Faculty of Medicine, Universitas Sebelas Maret Surakarta, Indonesia Jl. Ir Sutami 36 A Surakarta Indonesia 53126 (Indonesia)

    2016-02-08

    Bandage is a medical device that is essential for wound dressing. To improve the performance of the bandage, it has been coated by silver-chitosan nanocomposites (Ag/Chit) with pad-dry-cure method. The nanocomposites were performed by chemical reduction method at room temperature using glucose as reducing agent, sodium hydroxide (NaOH) as accelerator reagent, silver nitrate (AgNO{sub 3}) as metal precursor and chitosan as stabilizing agent. Localized surface plasmon resonance (LSPR) absorption band of silver nanoparticles was investigated using UV-Vis spectrophotometer. The bandage coated Ag/Chit nanocomposites (B-Ag/Chit) were characterized by fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscope (SEM). In addition, antibacterial activity of the bandage toward Gram positive (Staphylococcus aureus) and Gram negative (Escherichia coli) were also studied. The formation of silver nanoparticles was confirmed by the appearance of LSPR absorption peak at 412.2 – 423.2 nm. Coating of nanocomposite cause increasing rigidity of bandage and decreasing on crystallinity. The bandages of B-Ag/Chit demonstrated good activity against both Gram positive (S. aureus) and Gram negative (E.Coli). Thus the bandages have a potential to be used for antibacterial wound dressing application.

  4. Facile route for preparation of silver nanoparticle-coated precipitated silica

    Science.gov (United States)

    Quang, Dang Viet; Sarawade, Pradip B.; Hilonga, Askwar; Park, Sung Dae; Kim, Jong-Kil; Kim, Hee Taik

    2011-02-01

    In this research, a facile route was used to prepare silver nanoparticle-coated precipitated silica using sodium silicate, a cheap precursor. Precipitated silica (PS) was synthesized by dropping 8% H2SO4 into a mixed solution of sodium silicate 24% (Na2O·3.4SiO2) and NaCl 4%; under constant stirring. The precipitated silica was then modified by simultaneous addition of 3-aminopropyltriethoxysilane (3-APTES) and 8% H2SO4. The resulting material was aged at 80 °C for 1 h to produce amino-functionalized precipitated silica (AFPS). Silver nanoparticle-coated precipitated silica (Ag-NPS) was synthesized by adding silver nitrate (AgNO3). The synthesis procedure also involved mixing for 2 h and dropping 0.05 M sodium borohydride (NaBH4). The final products, namely, PS, AFPS, and Ag-NPS were characterized using BET analyzer, FE-SEM, TEM and XRD. Silver nanoparticles with an average size ranging from 18 to 25 nm were found mostly coated on the exterior layer of the precipitated silica. The synthesis method reported in this work is facile and might be used for large-scale industrial production of inexpensive Ag-NPS.

  5. Biocompatible Silver-containing a-C:H and a-C coatings: AComparative Study

    Energy Technology Data Exchange (ETDEWEB)

    Endrino, Jose Luis; Allen, Matthew; Escobar Galindo, Ramon; Zhang, Hanshen; Anders, Andre; Albella, Jose Maria

    2007-04-01

    Hydrogenated diamond-like-carbon (a-C:H) and hydrogen-free amorphous carbon (a-C) coatings are known to be biocompatible and have good chemical inertness. For this reason, both of these materials are strong candidates to be used as a matrix that embeds metallic elements with antimicrobial effect. In this comparative study, we have incorporated silver into diamond-like carbon (DLC) coatings by plasma based ion implantation and deposition (PBII&D) using methane (CH4) plasma and simultaneously depositing Ag from a pulsed cathodic arc source. In addition, we have grown amorphous carbon - silver composite coatings using a dual-cathode pulsed filtered cathodic-arc (FCA) source. The silver atomic content of the deposited samples was analyzed using glow discharge optical spectroscopy (GDOES). In both cases, the arc pulse frequency of the silver cathode was adjusted in order to obtain samples with approximately 5 at.% of Ag. Surface hardness of the deposited films was analyzed using the nanoindentation technique. Cell viability for both a-C:H/Ag and a-C:/Ag samples deposited on 24-well tissue culture plates has been evaluated.

  6. Impact of polymer-coated silver nanoparticles on marine microbial communities: a microcosm study.

    Science.gov (United States)

    Doiron, K; Pelletier, E; Lemarchand, K

    2012-11-15

    The use of silver nanoparticles (AgNPs) in consumer products is increasing drastically and their potential environmental impacts on aquatic organisms from bacterial communities to vertebrates are not well understood. This study reports on changes in marine bacterial richness using denaturing gradient gel electrophoresis (DGGE), and overall community abundance determined by flow cytometry in marine microcosms exposed to polymer-coated AgNPs (20±5 nm) and ionic silver (Ag(+)). Our study clearly demonstrated that at low concentrations (5 and 50 μg L(-1) total silver), un-aggregated polymer-coated AgNPs and dissolved Ag(+) contamination produced similar effects: a longer lag phase suggesting an adaptation period for microorganisms. As richness decreased in the treated samples, this longer lag phase could correspond to the selection of a fraction of the initial community that is insensitive to silver contamination. Polymer-coated AgNPs preserved their bactericidal properties even under the high ionic strength of estuarine waters.

  7. Calcium phosphate coating containing silver shows high antibacterial activity and low cytotoxicity and inhibits bacterial adhesion

    Energy Technology Data Exchange (ETDEWEB)

    Ando, Yoshiki, E-mail: andoy@jmmc.jp [Division of Microbiology, Department of Pathology and Microbiology, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga 849-8501 (Japan); Research Department, Japan Medical Materials Corporation, Uemura Nissei Bldg.9F 3-3-31 Miyahara, Yodogawa-ku, Osaka 532-0003 (Japan); Miyamoto, Hiroshi [Division of Microbiology, Department of Pathology and Microbiology, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga 849-8501 (Japan); Noda, Iwao; Sakurai, Nobuko [Research Department, Japan Medical Materials Corporation, Uemura Nissei Bldg.9F 3-3-31 Miyahara, Yodogawa-ku, Osaka 532-0003 (Japan); Akiyama, Tomonori [Division of Microbiology, Department of Pathology and Microbiology, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga 849-8501 (Japan); Yonekura, Yutaka; Shimazaki, Takafumi; Miyazaki, Masaki; Mawatari, Masaaki; Hotokebuchi, Takao [Department of Orthopaedic Surgery, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga 849-8501 (Japan)

    2010-01-01

    Surgical site infection is one of the serious complications of orthopedic implants. In order to reduce the incidence of implant-associated infections, we developed a novel coating technology of calcium phosphate (CP) containing silver (Ag), designated Ag-CP coating, using a thermal spraying technique. In this study, we evaluated the antibacterial efficacy and biological safety of this coating. In vitro antibacterial activity tests showed that the growths of Escherichia coli, Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) are completely suppressed on Ag-CP coating. In vitro bacterial adherence tests revealed that the number of adherent bacteria on the surface of this coating is significantly less (p < 0.02) than that on the surface of the CP coating. Moreover, the Ag-CP coating completely inhibits MRSA adhesion [<10 colony-forming units (CFU)] when 10{sup 2} CFU MRSA is inoculated. On the other hand, V79 Chinese hamster lung cells were found to grow on the Ag-CP coating as well as on the CP coating in a cytotoxicity test. These results indicate that the Ag-CP coating on the surface of orthopedic implants exhibits antibacterial activity and inhibits bacterial adhesion without cytotoxicity.

  8. Formation of Silver Nanoplates Layer on Amino Group Grafted Silica Coatings

    Directory of Open Access Journals (Sweden)

    Jurgis PILIPAVICIUS

    2016-05-01

    Full Text Available In this study the self-arrangement of Ag nanoplates on (3-Aminopropyltriethoxysilane (APTES silanized silica coatings was investigated. Silica coatings were made by sol-gel method and silanized in two different ways. The first one includes silanization in acidic 2-propanol solution, the other one – in dry toluene. Coatings were silanized by using different amounts of APTES in case of silanization in 2-propanol. Silver nanoplates layer of functionalized silica coatings was obtained via self-assembly. Coatings were investigated by atomic force microscopy (AFM, water contact angle measurements (CA, FT-IR analysis, and scanning electron microscopy (SEM. Research showed that dense Ag nanoplates arrangement occurs when there is a high amount of amino groups on the surface.DOI: http://dx.doi.org/10.5755/j01.ms.22.2.8405

  9. Fabrication of dendritic silver-coated copper powders by galvanic displacement reaction and their thermal stability against oxidation

    Science.gov (United States)

    Park, Yu-Seon; An, Chang Yong; Kannan, Padmanathan Karthick; Seo, Nary; Zhuo, Kai; Yoo, Tae Kyong; Chung, Chan-Hwa

    2016-12-01

    Two steps of wet chemical processes have been developed for the preparation of core-shell nanostructures of copper and silver, which is a facile and low cost method for the production of large quantity of dendritic powders. First step involves a galvanic displacement reaction with hydrogen evolution which is the motive force of spontaneous electrochemical reaction. To achieve the core-shell structure, silver has been coated on the dendritic copper using the galvanic displacement reaction. The dendritic silver-coated copper powders exhibit high surface-area, excellent conductivity, and good oxidation resistance. It has been found that silver-coated copper powders maintain the electrical conductivity even after annealing at 150 °C for several to tens of minutes, thus it is a promising material and an alternative to pure silver powders in printed electronics application.

  10. Ultrasonically spray coated silver layers from designed precursor inks for flexible electronics

    Science.gov (United States)

    Marchal, W.; Vandevenne, G.; D'Haen, J.; Almeida, A. Calmont de Andrade; Durand Sola, M. A., Jr.; van den Ham, E. J.; Drijkoningen, J.; Elen, K.; Deferme, W.; Van Bael, M. K.; Hardy, A.

    2017-05-01

    Integration of electronic circuit components onto flexible materials such as plastic foils, paper and textiles is a key challenge for the development of future smart applications. Therefore, conductive metal features need to be deposited on temperature sensitive substrates in a fast and straightforward way. The feasibility of these emerging (nano-) electronic technologies depends on the availability of well-designed deposition techniques and on novel functional metal inks. As ultrasonic spray coating (USSC) is one of the most promising techniques to meet the above requirements, innovative metal organic decomposition (MOD) inks are designed to deposit silver features on plastic foils. Various amine ligands were screened and their influence on the ink stability and the characteristics of the resulting metal depositions were evaluated to determine the optimal formulation. Eventually, silver layers with excellent performance in terms of conductivity (15% bulk silver conductivity), stability, morphology and adhesion could be obtained, while operating in a very low temperature window of 70 °C-120 °C. Moreover, the optimal deposition conditions were determined via an in-depth analysis of the ultrasonically sprayed silver layers. Applying these tailored MOD inks, the USSC technique enabled smooth, semi-transparent silver layers with a tunable thickness on large areas without time-consuming additional sintering steps after deposition. Therefore, this novel combination of nanoparticle-free Ag-inks and the USSC process holds promise for high throughput deposition of highly conductive silver features on heat sensitive substrates and even 3D objects.

  11. The influence of silver content on the tribological and antimicrobial properties of ZrN/Ag nanocomposite coatings.

    Science.gov (United States)

    Kelly, P J; Whitehead, K A; Li, H; Verran, J; Arnell, R D

    2011-06-01

    ZrN/Ag nanocomposite coatings with varying silver contents were produced by co-deposition in a dual pulsed magnetron sputtering system. The coatings were characterised using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), scratch adhesion testing, thrust washer wear testing and nanoindentation. The hardness of the ZrN/Ag coatings and the friction coefficient running unlubricated against a steel counterface decreased with increasing silver content, whereas the coating-to-substrate adhesion increased for coatings with higher silver contents, compared to a 'pure' ZrN coating. The antimicrobial properties of the coatings were investigated using two well established microbiological assay techniques: zones of inhibition and a NBT (nitro-blue tetrazolium) redox dye. Zones of inhibition were used to determine the extent of silver ion release from the nanocomposite materials, and a NBT (nitro-blue tetrazolium) redox dye was used to determine the antimicrobial effectiveness of the surfaces following incubation. The microorganisms tested were Pseudomonas aeruginosa (P. aeruginosa), Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Whilst no zones of inhibition were observed for S. aureus, on any of the surfaces, the diameter of the 'kill' zones generally increased with increasing silver content for the other microorganisms. For the NBT assays, after incubation, no P. aeruginosa colony forming units were observed on any surface and the number of viable cells of E. coli and S. aureus decreased with increasing silver content, compared to a 'pure' ZrN surface.

  12. Study of electroplated silver-palladium biofouling inhibiting coating

    DEFF Research Database (Denmark)

    Chiang, Wen-Chi; Hilbert, Lisbeth Rischel; Schroll, Casper

    2008-01-01

    Biofouling can cause many undesirable effects in industrial and medical settings. In this study, a new biofouling inhibiting Ag-Pd surface was designed to form an inhibiting effect by itself. This design was based on silver combined with nobler palladium, both with catalytic properties. Owing...... to the potential difference between silver and palladium while contacting with an electrolyte, the surface can form numerous discrete anodic and cathodic areas, so that an inhibiting reaction can occur. In this paper, a series of electrochemical and biological investigations were conducted to study the properties...... and biofouling inhibiting mechanism of these surfaces. In this study, the evidence is presented that the inhibiting effect can be caused by the electrochemical interactions and/or electric field between Pd and Ag/AgCl combined with an organic environment....

  13. Comparison of Heat Transfer Coefficients of Silver Coated and Chromium Coated Copper Tubes of Condenser in Dropwise Condensation

    Directory of Open Access Journals (Sweden)

    Er. Shivesh Kumar

    2016-09-01

    Full Text Available Since centuries steam is being used in power generating system. The steam leaving the power unit is reconverted into water in a condenser designed to transfer heat from the steam to the cooling water as rapidly and as efficiently as possible. The efficiency of condenser depends on rate of condensation and mode of condensation of steam in the condenser. The increase in efficiency of the condenser enhances the heat transfer co-efficient which in turn results in economic design of condenser and reduced pumping power for a desired output. Higher heat transfer coefficient in condensers is beneficial in the industrial applications e.g., Sugar industry, ships propulsion, nuclear power reactor, power generating system, production of Liquefied petroleum gases, liquid nitrogen and liquid oxygen. In the present experimental study, comparison of heat transfer coefficients of silver coated and chromium coated copper tubes of condenser have been performed. it has been observed that inside heat transfer coefficient (hᵢ, outside heat transfer coefficient (h₀ and overall heat transfer coefficient (U associated with silver coated condenser made of copper is more than that of chromium coated condenser made of copper. It is also observed that all the three types of heat transfer coefficient increases with increase of steam pressure [1].

  14. High Reflectivity, Broad-Band Silver Coating Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Future space telescopes such as the Super Nova Acceleration Probe (SNAP) require exceptionally reflective coatings applied to mirrors several meters in diameter. In...

  15. Breakthrough analysis for water disinfection using silver nanoparticles coated resin beads in fixed-bed column

    Energy Technology Data Exchange (ETDEWEB)

    Mthombeni, Nomcebo H. [Department of Chemical and Metallurgical Engineering, Tshwane University of Technology, Pretoria (South Africa); Mpenyana-Monyatsi, Lizzy [Department of Environmental, Water and Earth Sciences, Tshwane University of Technology, Pretoria (South Africa); Onyango, Maurice S., E-mail: OnyangoMS@tut.ac.za [Department of Chemical and Metallurgical Engineering, Tshwane University of Technology, Pretoria (South Africa); Momba, Maggie N.B. [Department of Environmental, Water and Earth Sciences, Tshwane University of Technology, Pretoria (South Africa)

    2012-05-30

    Highlights: Black-Right-Pointing-Pointer Performance of silver nanoparticles coated resin in water disinfection is presented. Black-Right-Pointing-Pointer Sigmoidal models are used to describe breakthrough curves. Black-Right-Pointing-Pointer The performance of the media in water disinfection is affected by process variables. Black-Right-Pointing-Pointer Test with environmental water shows the media is effective in water disinfection. - Abstract: This study demonstrates the use of silver nanoparticles coated resin beads in deactivating microbes in drinking water in a column filtration system. The coated resin beads are characterized using X-ray diffraction (XRD), Fourier transform infra-red (FT-IR), scanning electron microscope (SEM), transmission electron microscope (TEM) and energy dispersive spectroscopy (EDS) to confirm the functional groups, morphology and the presence of silver nanoparticles on the surface of the resin. The performance of the coated resin is evaluated as a function of bed mass, initial bacterial concentration and flow rate using Escherichia coli as model microbial contaminant in water. The survival curves of E. coli are expressed as breakthrough curves (BTCs), which are modeled using sigmoidal regression equations to obtain relevant rate parameters. The number of bed volumes processed at breakthrough point and capacity of the bed are used as performance indicators. Results show that performance increases with a decrease in initial bacterial concentration, an increase in flow rate and an increase in bed mass.

  16. PEGylated chitosan protected silver nanoparticles as water-borne coating for leather with antibacterial property.

    Science.gov (United States)

    Liu, Gongyan; Li, Kaijun; Luo, Quanqing; Wang, Haibo; Zhang, Zongcai

    2017-03-15

    Development of eco-labeled and effectively antibacterial coatings for final leather products has been desiderated both by industry and by consumers. Herein, PEGylated chitosan modified silver nanoparticles (PEG-g-CS@AgNPs) were prepared and characterized by UV-vis spectroscopy, transmission electron microscopy and dynamic light scattering. The antimicrobial activity of such silver nanoparticles was investigated against Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus), exhibiting much lower minimum inhibitory concentration (MIC) than chitosan or PEG-g-CS. Water-borne coating was formed by immobilizing the PEG-g-CS@AgNPs onto the leather surface through the electrostatic interaction between amino groups of chitosan and carboxyl groups of leather collagen. Scanning electron microscopy and water contact angle were employed to study the coating's morphology and hydrophilicity, respectively. After coating, leather samples showed significantly high bactericidal efficiency with reusability after release of dead cells from the coating by simply water washing. The excellent antibacterial property of PEG-g-CS@AgNPs coating was ascribed to the combination of bacteria-resistance and bacteria-release by PEGylation, and dual bacteria-killing based on chitosan and Ag(+) release.

  17. SiO{sub 2} coating of silver nanoparticles by photoinduced chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Boies, Adam M; Girshick, Steven L [Department of Mechanical Engineering, University of Minnesota, 111 Church Street SE, Minneapolis, MN 55455 (United States); Roberts, Jeffrey T [Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, MN 55455 (United States); Zhang Bin; Nakamura, Toshitaka; Mochizuki, Amane, E-mail: jtrob@umn.ed, E-mail: slg@umn.ed [Nitto Denko Technical Corporation, 501 Via Del Monte, Oceanside, CA 92058 (United States)

    2009-07-22

    Gas-phase silver nanoparticles were coated with silicon dioxide (SiO{sub 2}) by photoinduced chemical vapor deposition (photo-CVD). Silver nanoparticles, produced by inert gas condensation, and a SiO{sub 2} precursor, tetraethylorthosilicate (TEOS), were exposed to vacuum ultraviolet (VUV) radiation at atmospheric pressure and varying temperatures. The VUV photons dissociate the TEOS precursor, initiating a chemical reaction that forms SiO{sub 2} coatings on the particle surfaces. Coating thicknesses were measured for a variety of operation parameters using tandem differential mobility analysis and transmission electron microscopy. The chemical composition of the particle coatings was analyzed using energy dispersive x-ray spectrometry and Fourier transform infrared spectroscopy. The highest purity films were produced at 300-400 {sup 0}C with low flow rates of additional oxygen. The photo-CVD coating technique was shown to effectively coat nanoparticles and limit core particle agglomeration at concentrations up to 10{sup 7} particles cm{sup -3}.

  18. Chemical, mechanical and antibacterial properties of silver nanocluster/silica composite coated textiles for safety systems and aerospace applications

    Energy Technology Data Exchange (ETDEWEB)

    Ferraris, S., E-mail: sara.ferraris@polito.it [Politecnico di Torino, Torino, C.so Duca degli Abruzzi 24, 10129 (Italy); Perero, S.; Miola, M.; Vernè, E. [Politecnico di Torino, Torino, C.so Duca degli Abruzzi 24, 10129 (Italy); Rosiello, A.; Ferrazzo, V.; Valletta, G. [Aero Sekur S.p.A., Aprilia, via delle Valli 46, 04011 (Italy); Sanchez, J.; Ohrlander, M. [Bactiguard AB, Biblioteksgatan 25, Box 5070, SE-10242, Stockholm (Sweden); Tjörnhammar, S.; Fokine, M.; Laurell, F. [KTH Royal Institute of Technology, Department of Applied Physics, Roslagstullsbacken 21, SE-106 91 Laserphysics, Stockholm (Sweden); Blomberg, E. [KTH Royal Institute of Technology, Div. Surface and Corrosion Science, Drottning Kristinas väg 51, SE-100 44, Stockholm (Sweden); SP Technical Research Institute of Sweden, Chemistry, Materials and Surfaces, Box 5607, SE-114 86, Stockholm (Sweden); Skoglund, S.; Odnevall Wallinder, I. [KTH Royal Institute of Technology, Div. Surface and Corrosion Science, Drottning Kristinas väg 51, SE-100 44, Stockholm (Sweden); Ferraris, M. [Politecnico di Torino, Torino, C.so Duca degli Abruzzi 24, 10129 (Italy)

    2014-10-30

    Highlights: • Silver nanoclusters-silica composite coatings were deposited on textiles. • Textiles for NBC protection suites and for aerospace applications were considered. • The coating process conferred all textiles a good antibacterial activity. • The coating does not alter the properties of bare textiles. - Abstract: This work describes the chemical, mechanical and antibacterial properties of a novel silver nanocluster/silica composite coating, obtained by sputtering, on textiles for use in nuclear bacteriological and chemical (NBC) protection suites and for aerospace applications. The properties of the coated textiles were analyzed in terms of surface morphology, silver concentration and silver release in artificial sweat and synthetic tap water, respectively. No release of silver nanoparticles was observed at given conditions. The water repellency, permeability, flammability and mechanical resistance of the textiles before and after sputtering demonstrated that the textile properties were not negatively affected by the coating. The antibacterial effect was evaluated at different experimental conditions using a standard bacterial strain of Staphylococcus aureus and compared with the behavior of uncoated textiles. The coating process conferred all textiles a good antibacterial activity. Optimal deposition conditions were elaborated to obtain sufficient antibacterial action without altering the aesthetical appearance of the textiles. The antibacterial coating retained its antibacterial activity after one cycle in a washing machine only for the Nylon based textile.

  19. Silver-nanoparticle-coated biliary stent inhibits bacterial adhesion in bacterial cholangitis in swine

    Institute of Scientific and Technical Information of China (English)

    Wei Wen; Li-Mei Ma; Wei He; Xiao-Wei Tang; Yin Zhang; Xiang Wang; Li Liu; Zhi-Ning Fan

    2016-01-01

    BACKGROUND: One of the major limitations of biliary stents is the stent occlusion, which is closely related to the over-growth of bacteria. This study aimed to evaluate the feasibility of a novel silver-nanoparticle-coated polyurethane (Ag/PU) stent in bacterial cholangitis model in swine. METHODS: Ag/PU was designed by coating silver nanopar-ticles on polyurethane (PU) stent. Twenty-four healthy pigs with bacterial cholangitis using Ag/PU and PU stents were ran-domly divided into an Ag/PU stent group (n=12) and a PU stent group (n=12), respectively. The stents were inserted by standard endoscopic retrograde cholangiopancreatography. Laboratory assay was performed for white blood cell (WBC) count, alanine aminotransferase (ALT), interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α) at baseline time, 8 hours, 1, 2, 3, and 7 days after stent placements. The segment of bile duct containing the stent was examined histologically ex vivo. Implanted bili-ary stents were examined by a scan electron microscope. The amount of silver release was also measured in vitro. RESULTS: The number of inflammatory cells and level of ALT, IL-1β and TNF-α were significantly lower in the Ag/PU stent group than in the PU stent group. Hyperplasia of the mucosa was more severe in the PU stent group than in the Ag/PU stent group. In contrast to the biofilm of bacteria on the PU stent, fewer bacteria adhered to the Ag/PU stent. CONCLUSIONS: PU biliary stents modified with silver nanoparticles are able to alleviate the inflammation of pigs with bacterial cholangitis. Silver-nanoparticle-coated stents are resistant to bacterial adhesion.

  20. Ion-exchange voltammetry of dopamine at Nafion-coated glassy carbon electrodes: quantitative features of ion-exchange partition and reassessment on the oxidation mechanism of dopamine in the presence of excess ascorbic acid.

    Science.gov (United States)

    Rocha, Luciana S; Carapuça, Helena M

    2006-10-01

    The incorporation/exclusion features of dopamine (DA), ascorbic acid (AA) and uric acid (UA) are evaluated for Nafion (NA)-coated glassy carbon electrodes (GCE) of different thicknesses. The ion-exchange partition of DA(+) between the NA film and the sodium phosphate electrolyte is evaluated by determining the partition coefficient (k(D)) and the apparent diffusion coefficient (D(app)) in thick NA films which were 401 and 1.5 x 10(-9) cm(2) s(-1), respectively. The solution diffusion coefficient was found to be 6.0 x 10(-6) cm(2) s(-1). Also, the effect of NA loading and of the voltammetric timescale on DA voltammetry in the presence of excess AA is assessed, at physiologic like conditions. It is demonstrated that, although AA is excluded at the NA coating, a catalytic regeneration of DA, induced by AA, occurs at the interface NA film/electrolyte resulting from the diffusion of the o-quinone product of DA oxidation from the electrode surface to that interface. The interference of AA in the voltammetric signal of DA is eliminated using 18 microg mm(-2) NA films and v> or =0.5 V s(-1). Therefore, fast, selective and sensitive voltammetric analysis of DA at concentrations<100 microM in the presence of excess AA, e.g., 1 mM is achieved.

  1. Surface-enhanced Raman spectroscopy using silver-coated porous glass-ceramic substrates.

    Science.gov (United States)

    Pan, Z; Zavalin, A; Ueda, A; Guo, M; Groza, M; Burger, A; Mu, R; Morgan, S H

    2005-06-01

    Surface-enhanced Raman scattering (SERS) has been studied using a silver-coated porous glass-ceramic material as a new type of substrate. The porous glass-ceramic is in the CaO-TiO2-P2O5 system prepared by controlled crystallization and subsequent chemical leaching of the dense glass-ceramic, leaving a solid skeleton with pores ranging in size from 50 nm to submicrometer. Silver was coated on the surface of the porous glass-ceramic by radio frequency (RF) sputtering or e-beam evaporation in vacuum. SERS spectra of excellent quality were obtained from several dyes and carboxylic acid molecules, including rhodamine 6G, crystal violet, isonicotinic acid, and benzoic acid, using this new substrate. This new substrate showed a good compatibility with these molecules. The porous glass ceramic with a nanometer-structured surface accommodated both test molecules and silver film. The absorbed molecules were therefore better interfaced with silver for surface-enhanced Raman scattering.

  2. Examination of Ostwald ripening in the photocatalytic growth of silver nanoparticles on titanium dioxide coatings

    Energy Technology Data Exchange (ETDEWEB)

    Piwoński, Ireneusz, E-mail: irek@uni.lodz.pl [University of Lodz, Faculty of Chemistry, Department of Materials Technology and Chemistry, Pomorska 163, 90-236 Lodz (Poland); Spilarewicz-Stanek, Kaja; Kisielewska, Aneta [University of Lodz, Faculty of Chemistry, Department of Materials Technology and Chemistry, Pomorska 163, 90-236 Lodz (Poland); Kądzioła, Kinga [Molecular and Nanostructural Biophysics Laboratory, Technopark Łódź, Dubois 114/116, 93-465 Lodz (Poland); Cichomski, Michał; Ginter, Joanna [University of Lodz, Faculty of Chemistry, Department of Materials Technology and Chemistry, Pomorska 163, 90-236 Lodz (Poland)

    2016-06-15

    Graphical abstract: The growth of silver nanoparticles (AgNPs) according to Ostwald ripening process. - Highlights: • Silver nanoparticles were grown on the sol–gel TiO{sub 2} coating by photoreduction of silver ions at short illumination times. • Size and number of nanoparticles were measured using scanning electron microscopy. • Large nanoparticles grow at the expense of small nanoparticles according to Ostwald ripening mechanism. - Abstract: Silver nanoparticles (AgNPs) were grown on the surface of titanium dioxide coating (TiO{sub 2}) using a photochemical method. The size and number of AgNPs were monitored using scanning electron microscopy (SEM) after 20, 30, 180 and 300 s of UV illumination. It was found that for short illumination times (20 s) a significant number of small nanoparticles were grown. However, after an additional 10 s of illumination, small nanoparticles were subject to decomposition and the released Ag{sup +} ions were utilized for the growth of the existing larger nanoparticles, causing an increase in their dimensions. The observed results indicate that the nucleation and further growth of AgNPs proceed according to Ostwald ripening. For longer illumination times (180, 300 s) a coalescence of closely located particles was observed.

  3. Evaluation of antimicrobial efficacy of nano coated silver-titania metallic plates against selective pathogens

    Directory of Open Access Journals (Sweden)

    Mohamad, S.M.

    2012-01-01

    Full Text Available Aim: Nanotechnology is an increasingly growing field with its current application in Science and Technology for the purpose of manufacture of novel materials at the nanoscale level. Silver-Titania nanoparticles (AgTiO2-NPs have been known to have inhibitory and bactericidal effects.Methodology and Results: In the present study, stable silver-titania nanoparticles coated metallic blocks were prepared for testing their efficacy against selected bacterial pathogens like Escherichia coli and Staphylococcus aureus. In the experimental part, the bacterial pathogens were inoculated on silver-titania nanoparticle coated blocks and the treatment was carried out in „0‟ time and „24‟ h interval and were enumerated.Conclusion, significance and impact of study:The results were compared with the control (uncoated metallic blocks and analyzed by using Japanese Industrial Standard (JIS Z2801:2000 method. From this study, it was concluded that silver-titania nanoparticles has inhibitory effect on bacterial pathogen tested.

  4. Characterization and antimicrobial performance of nano silver coatings on leather materials

    OpenAIRE

    N. Lkhagvajav; Koizhaiganova,M.; Yasa, I.; Çelik, E.; Ö. Sari

    2015-01-01

    In this study, the characterization and the antimicrobial properties of nano silver (nAg) coating on leather were investigated. For this purpose, turbidity, viscosity and pH of nAg solutions prepared by the sol-gel method were measured. The formation of films from these solutions was characterized according to temperature by Differential Thermal Analysis-Thermogravimetry (DTA-TG) equipment. The surface morphology of treated leathers was observed using Scanning Electron Microscopy (SEM). The a...

  5. Silver nanowire/optical adhesive coatings as transparent electrodes for flexible electronics.

    Science.gov (United States)

    Miller, Michael S; O'Kane, Jessica C; Niec, Adrian; Carmichael, R Stephen; Carmichael, Tricia Breen

    2013-10-23

    We present new flexible, transparent, and conductive coatings composed of an annealed silver nanowire network embedded in a polyurethane optical adhesive. These coatings can be applied to rigid glass substrates as well as to flexible polyethylene terephthalate (PET) plastic and elastomeric polydimethylsiloxane (PDMS) substrates to produce highly flexible transparent conductive electrodes. The coatings are as conductive and transparent as indium tin oxide (ITO) films on glass, but they remain conductive at high bending strains and are more durable to marring and scratching than ITO. Coatings on PDMS withstand up to 76% tensile strain and 250 bending cycles of 15% strain with a negligible increase in electrical resistance. Since the silver nanowire network is embedded at the surface of the optical adhesive, these coatings also provide a smooth surface (root mean squared surface roughness<10 nm), making them suitable as transparent conducting electrodes in flexible light-emitting electrochemical cells. These devices continue to emit light even while being bent to radii as low as 1.5 mm and perform as well as unstrained devices after 20 bending cycles of 25% tensile strain.

  6. Investigation of silver impact on hydroxyapatite/lignin coatings electrodeposited on titanium

    Energy Technology Data Exchange (ETDEWEB)

    Eraković, Sanja; Janković, Ana [Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11 000 Belgrade (Serbia); Matić, Ivana Z.; Juranić, Zorica D. [Institute of Oncology and Radiology of Serbia, Pasterova 14, 11 000 Belgrade (Serbia); Vukašinović-Sekulić, Maja [Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11 000 Belgrade (Serbia); Stevanović, Tatjana [Département des sciences du bois et de la forêt, Université Laval, 2425 rue de la Terrasse, Québec (Canada); Mišković-Stanković, Vesna, E-mail: vesna@tmf.bg.ac.rs [Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11 000 Belgrade (Serbia)

    2013-11-01

    Silver doped hydroxyapatite (HAP) [Ca{sub 9.95}Ag{sub 0.05}(PO{sub 4}){sub 6}(OH){sub 2}] composite coatings with natural polymer organosolv lignin (Lig) were produced by electrophoretic deposition (EPD) on titanium. Coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), field emission scanning electron microscopy (FE-SEM), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). The corrosion stability of electrodeposited coatings was evaluated in vitro in Kokubo's simulated body fluid (SBF) at 37 °C using electrochemical impedance spectroscopy (EIS). Antimicrobial properties are directly proportional to the rate of silver ions release from the coatings, determined from inductively coupled plasma spectrometry (ICP-AES). The obtained results are in good agreement with viability of pathogenic bacteria strain Staphylococcus aureus TL in suspension, which had completely disappeared after 24 h. Composite Ag/HAP/Lig coatings were confirmed as non-toxic for healthy immunocompetent peripheral blood mononuclear cells (PBMC). - Highlights: • Biocompatibility and antimicrobial properties of Ag/HAP/Lig were investigated. • Ag ions embedded into HAP lattice are released from material upon immersion in SBF. • Strong antibactericidal effect against Staphylococcus aureus. • Non-toxic properties of nanocomposite confirmed against PBMC cells. • Promising result for the future developments of bioactive implant materials.

  7. Antibacterial and bioactivity of silver substituted hydroxyapatite/TiO2 nanotube composite coatings on titanium

    Science.gov (United States)

    Yan, Yajing; Zhang, Xuejiao; Huang, Yong; Ding, Qiongqiong; Pang, Xiaofeng

    2014-09-01

    Hydroxyapatite doped with Ag+ ions (AgHAp) was synthesized via electrochemical deposition method on anodized titanium. The samples were characterized via X-ray diffraction, Fourier transform infrared spectrum analysis, X-Ray photoelectron spectroscopy and scanning electron microscopy to investigate the phase formation and microstructure of the samples. Highly ordered TiO2 nanotubes with a diameter of 100 nm were successfully synthesized, and the AgHAp coating was deposited on the TiO2 nanotubes, which has a thickness of about 17.7 ± 1.5 μm. Moreover, silver was uniformly-distributed on the nanotubes. Bioactivity and electrochemical studies were performed for the AgHAp-coated TiO2 in a simulated body fluid, where significant good bioactivity and corrosion resistance were exhibited. The antibacterial and osteoblast cell adhesion tests in vitro revealed that the AgHAp coating with 2.03 wt% silver had significant antibacterial and osteogenic properties. Thus, the AgHAp coating was regarded as a promising candidate for coating orthopedic implants.

  8. Cytocompatibility and antibacterial properties of zirconia coatings with different silver contents on titanium

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Heng-Li [School of Dentistry, China Medical University, Taichung 404, Taiwan (China); Chang, Yin-Yu, E-mail: yinyu@mail2000.com.tw [Department of Mechanical and Computer-Aided Engineering, National Formosa University, Yunlin 632, Taiwan (China); Chen, Ya-Chi [Department of Materials Science and Engineering, Mingdao University, Changhua 52345, Taiwan (China); Lai, Chih-Ho [School of Medicine, China Medical University, Taichung 404, Taiwan (China); Chen, Michael Y.C. [School of Dentistry, China Medical University, Taichung 404, Taiwan (China); Division of Oral and Maxillofacial Surgery, China Medical University Hospital, Taichung 404, Taiwan (China)

    2013-12-31

    This study used a twin-gun magnetron sputtering system to deposit ZrO{sub 2}-silver (Ag) coatings on biograde pure-titanium implant materials, and the Ag content in the deposited coatings was controlled by the magnetron power. The films were then annealed using rapid thermal annealing at 350 °C for 2 min to induce the nucleation and growth of nanoparticles on the film surface. Staphylococcus aureus (S. aureus) and Actinobacillus actinomycetemcomitans (A. actinomycetemcomitans) were used for in vitro antibacterial analyses. The cytocompatibility, mRNA expression, and adhesive morphology of human gingival fibroblast (HGF) cells on the coatings were also determined. The obtained results suggest that ZrO{sub 2}-Ag composite coatings containing less than 10.6 at.% Ag show hydrophobicity, good viability and proliferation of HGF cells, and antibacterial effects on S. aureus and A. actinomycetemcomitans. Moreover, the antibacterial performance of ZrO{sub 2}-Ag coatings is superior to that pure-titanium whilst maintaining biological compatibility. - Highlights: • The annealed ZrO{sub 2}-Ag coatings showed a tetragonal-and-monoclinic structure. • Nanoparticles were well distributed in the annealed ZrO{sub 2}-Ag composite coatings. • The ZrO{sub 2}-Ag coated Ti showed hydrophobic feature. • The ZrO{sub 2}-Ag showed good antibacterial performance. • The ZrO{sub 2}-Ag showed good human gingival fibroblast cell viability.

  9. Biological responses of silver-coated thermosets: an in vitro and in vivo study.

    Science.gov (United States)

    Marsich, E; Travan, A; Donati, I; Turco, G; Kulkova, J; Moritz, N; Aro, H T; Crosera, M; Paoletti, S

    2013-02-01

    Bisphenol A glycidylmethacrylate (BisGMA)/triethyleneglycol dimethacrylate (TEGDMA) thermosets are biomaterials commonly employed for orthopedic and dental applications; for both these fields, bacterial adhesion to the surface of the implant represents a major issue for the outcome of the surgical procedures. In this study, the antimicrobial properties of a nanocomposite coating formed by polysaccharide 1-deoxylactit-1-yl chitosan (Chitlac) and silver nanoparticles (nAg) on methacrylate thermosets were studied. The Chitlac-nAg system showed good anti-bacterial and anti-biofilm activity although its biocidal properties can be moderately, albeit significantly, inhibited by serum proteins. In vitro studies on the silver release kinetic in physiological conditions showed a steady metal release associated with a gradual loss of antimicrobial activity. However, after 3weeks there was still effective protection against bacterial colonization which could be accounted for by the residual silver. This time-span could be considered adequate to confer short-term protection from early peri-implant infections. Preliminary in vivo tests in a mini-pig animal model showed good biological compatibility of Chitlac-nAg-coated materials when implanted in bony tissue. The comparison was made with implants of titanium Ti6Al4V alloy and with a Chitlac-coated thermoset. Bone healing patterns and biocompatibility parameters observed for nAg-treated material were comparable with those observed for control implants.

  10. Cavitation erosion of silver plated coating at different temperatures and pressures

    Energy Technology Data Exchange (ETDEWEB)

    Hattori, Shuji; Motoi, Yoshihiro [Graduate School of Engineering, University of Fukui, 3-9-1 Bunkyo, Fuku-shi, Fukui 910-8507 (Japan); Kikuta, Kengo; Tomaru, Hiroshi [IHI Corperation, TOYOSU IHI BUILDING, 1-1, Toyosu 3-chome, Koto-ku, Tokyo 1358710 (Japan)

    2014-04-11

    Cavitation often occurs in inducer pumps used for space rockets. Silver plated coating on the inducer liner faces the damage of cavitation. Therefore, it is important to study about the cavitation erosion resistance for silver plated coating at several operating conditions in the inducer pumps. In this study, the cavitation erosion tests were carried for silver plated coating in deionized water and ethanol at several liquid temperatures (273K–400K) and pressures (0.10MPa–0.48MPa). The mass loss rate is evaluated in terms of thermodynamic parameter Σ proposed by Brennen [9], suppression pressure p–p{sub v} (p{sub v}: saturated vapor pressure) and acoustic impedance ρc (ρ: density and c: sound speed). Cavitation bubble behaviors depending on the thermodynamic effect and the liquid type were observed by high speed video camera. The mass loss rate is formulated by thermodynamic parameter Σ, suppression pressure p–p{sub v} and acoustic impedance ρc.

  11. Antimicrobial activity and cytocompatibility of silver nanoparticles coated catheters via a biomimetic surface functionalization strategy

    Science.gov (United States)

    Wu, Ke; Yang, Yun; Zhang, Yanmei; Deng, Jiexi; Lin, Changjian

    2015-01-01

    Catheter-related bloodstream infections are a significant problem in the clinic and may result in a serious infection. Here, we developed a facile and green procedure for buildup of silver nanoparticles (AgNPs) on the central venous catheters (CVCs) surface. Inspired by mussel adhesive proteins, dopamine was used to form a thin polydopamine layer and induce AgNPs formation without additional reductants or stabilizers. The chemical and physicochemical properties of AgNPs coated CVCs were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and water contact angle. The Staphylococcus aureus culture experiment was used to study the antibacterial properties. The cytocompatibility was assessed by water soluble tetrazolium salts (WST-1) assay, fluorescence staining, and scanning electron microscopy analysis. The results indicated that the CVCs surface was successfully coated with compact AgNPs. AgNPs were significantly well separated and spherical with a size of 30–50 nm. The density of AgNPs could be modulated by the concentration of silver nitrate solution. The antibacterial activity was dependent on the AgNPs dose. The high dose of AgNPs showed excellent antibacterial activity while associated with increased cytotoxicity. The appropriate density of AgNPs coated CVCs could exhibit improved biocompatibility and maintained evident sterilization effect. It is promising to design mussel-inspired silver releasing CVCs with both significant antimicrobial efficacy and appropriate biological safety. PMID:26664115

  12. Corrosion stability and bioactivity in simulated body fluid of silver/hydroxyapatite and silver/hydroxyapatite/lignin coatings on titanium obtained by electrophoretic deposition.

    Science.gov (United States)

    Eraković, Sanja; Janković, Ana; Veljović, Djordje; Palcevskis, Eriks; Mitrić, Miodrag; Stevanović, Tatjana; Janaćković, Djordje; Mišković-Stanković, Vesna

    2013-02-14

    Hydroxyapatite is the most suitable biocompatible material for bone implant coatings. However, its brittleness is a major obstacle, and that is why, recently, research focused on creating composites with various biopolymers. In this study, hydroxyapatite coatings were modified with lignin in order to attain corrosion stability and surface porosity that enables osteogenesis. Incorporating silver, well known for its antimicrobial properties, seemed the best strategy for avoiding possible infections. The silver/hydroxyapatite (Ag/HAP) and silver/hydroxyapatite/lignin (Ag/HAP/Lig) coatings were cathaphoretically deposited on titanium from ethanol suspensions, sintered at 900 °C in Ar, and characterized by X-ray diffraction, scanning electron microscopy, field emission scanning electron microscopy, attenuated total reflection Fourier transform infrared, and X-ray photoelectron spectroscopy. The corrosion stability of electrodeposited coatings was evaluated in vitro in Kokubo's simulated body fluid (SBF) at 37 °C using electrochemical impedance spectroscopy. Bioactivity was estimated by immersion in SBF to evaluate the formation of hydroxyapatite on the coating surface. A microcrystalline structure of newly formed plate-shaped carbonate-hydroxyapatite was detected after only 7 days, indicating enhanced bioactive behavior. Both coatings had good corrosion stability during a prolonged immersion time. Among the two, the Ag/HAP/Lig coating had a homogeneous surface, less roughness, and low values of contact angle.

  13. Size- and coating-dependent cytotoxicity and genotoxicity of silver nanoparticles evaluated using in vitro standard assays.

    Science.gov (United States)

    Guo, Xiaoqing; Li, Yan; Yan, Jian; Ingle, Taylor; Jones, Margie Yvonne; Mei, Nan; Boudreau, Mary D; Cunningham, Candice K; Abbas, Mazhar; Paredes, Angel M; Zhou, Tong; Moore, Martha M; Howard, Paul C; Chen, Tao

    2016-11-01

    The physicochemical characteristics of silver nanoparticles (AgNPs) may greatly alter their toxicological potential. To explore the effects of size and coating on the cytotoxicity and genotoxicity of AgNPs, six different types of AgNPs, having three different sizes and two different coatings, were investigated using the Ames test, mouse lymphoma assay (MLA) and in vitro micronucleus assay. The genotoxicities of silver acetate and silver nitrate were evaluated to compare the genotoxicity of nanosilver to that of ionic silver. The Ames test produced inconclusive results for all types of the silver materials due to the high toxicity of silver to the test bacteria and the lack of entry of the nanoparticles into the cells. Treatment of L5718Y cells with AgNPs and ionic silver resulted in concentration-dependent cytotoxicity, mutagenicity in the Tk gene and the induction of micronuclei from exposure to nearly every type of the silver materials. Treatment of TK6 cells with these silver materials also resulted in concentration-dependent cytotoxicity and significantly increased micronucleus frequency. With both the MLA and micronucleus assays, the smaller the AgNPs, the greater the cytotoxicity and genotoxicity. The coatings had less effect on the relative genotoxicity of AgNPs than the particle size. Loss of heterozygosity analysis of the induced Tk mutants indicated that the types of mutations induced by AgNPs were different from those of ionic silver. These results suggest that AgNPs induce cytotoxicity and genotoxicity in a size- and coating-dependent manner. Furthermore, while the MLA and in vitro micronucleus assay (in both types of cells) are useful to quantitatively measure the genotoxic potencies of AgNPs, the Ames test cannot.

  14. Electrical resistivity and dielectric properties of helical microorganism cells coated with silver by electroless plating

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Jun, E-mail: jun_cai@buaa.edu.cn [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, School of Mechanical Engineering and Automation, Beihang University, Beijing 100191 (China); Lan, Mingming; Zhang, Deyuan; Zhang, Wenqiang [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, School of Mechanical Engineering and Automation, Beihang University, Beijing 100191 (China)

    2012-09-01

    Highlights: Black-Right-Pointing-Pointer We use the microorganism cells as forming templates to fabricate the bio-based conductive particles. Black-Right-Pointing-Pointer The microorganism cells selected as forming templates are Spirulina platens, which are of natural helical shape and high aspect ratio. Black-Right-Pointing-Pointer The sliver-coated Spirulina cells are a kind of lightweight conductive particles. Black-Right-Pointing-Pointer The composites containing sliver-coated Spirulina cells exhibit a lower percolation value. - Abstract: In this paper, microorganism cells (Spirulina platens) were used as forming templates for the fabrication of the helical functional particles by electroless silver plating process. The morphologies and ingredients of the coated Spirulina cells were analyzed with scanning electron microscopy and energy dispersive spectrometer. The crystal structures were characterized by employing the X-ray diffraction. The electrical resistivity and dielectric properties of samples containing different volume faction of sliver-coated Spirulina cells were measured and investigated by four-probe meter and vector network analyzer. The results showed that the Spirulina cells were successfully coated with a uniform silver coating and their initial helical shapes were perfectly kept. The electrical resistivity and dielectric properties of the samples had a strong dependence on the volume content of sliver-coated Spirulina cells and the samples could achieve a low percolation value owing to high aspect ratio and preferable helical shape of Spirulina cells. Furthermore, the conductive mechanism was analyzed with the classic percolation theory, and the values of {phi}{sub c} and t were obtained.

  15. Acute and Subacute Toxicity In Vivo of Thermal-Sprayed Silver Containing Hydroxyapatite Coating in Rat Tibia

    Directory of Open Access Journals (Sweden)

    Masatsugu Tsukamoto

    2014-01-01

    Full Text Available To reduce the incidence of implant-associated infection, we previously developed a novel coating technology using hydroxyapatite (HA containing silver (Ag. This study examined in vivo acute and subacute toxicity associated with the Ag-HA coating in rat tibiae. Ten-week-old rats received implantation of HA-, 2% Ag-HA-, or 50% Ag-HA-coated titanium rods. Concentrations of silver in serum, brain, liver, kidneys, and spleen were measured in the acute phase (2–4 days after treatment and subacute phase (4–12 weeks after treatment. Biochemical and histological examinations of those organs were also performed. Mean serum silver concentration peaked in the acute phase and then gradually decreased. Mean silver concentrations in all examined organs from the 2% Ag-HA coating groups showed no significant differences compared with the HA coating group. No significant differences in mean levels of glutamic-oxaloacetic transaminase, glutamic-pyruvic transaminase, lactate dehydrogenase, creatinine, or blood urea nitrogen were seen between the three groups and controls. Histological examinations of all organs revealed no abnormal pathologic findings. No acute or subacute toxicity was seen in vivo for 2% Ag-HA coating or HA coating. Ag-HA coatings on implants may represent biologically safe antibacterial biomaterials and may be of value for reducing surgical-site infections related to implantation.

  16. Silver nanoparticle behaviour in lake water depends on their surface coating.

    Science.gov (United States)

    Jiménez-Lamana, Javier; Slaveykova, Vera I

    2016-12-15

    The present study examines the stability of silver nanoparticles (AgNPs) of three different coatings - citrate (CIT), polyvinyl pyrrolidone (PVP) and lipoic acid (LIP) and two sizes - 20 and 50nm in lake water (LW) over time. Using a combination of asymmetric flow field-flow fractionation (AsFlFFF), surface plasmon resonance (SPR), and single particle inductively coupled plasma mass spectrometry (SP-ICP-MS), the influence of size, surface coating, exposure time, as well as the presence and nature of dissolved organic matter (DOM) on the transformation of AgNPs at low environmental concentrations was thoroughly investigated. The results revealed that the AgNP stability in lake water are complex interplay between the surface coating characteristics, exposure time and presence and nature of DOM. Among the studied variables surface coating was found to play the major role of determining AgNPs behaviour in lake water. PVP-coated AgNPs agglomerated to a lesser extent as compared with the CIT- and LIP-AgNPs. For a given surface coating, DOM of pedogenic and aquagenic origin increased the stability of the AgNPs (LW+EPS>LW+SRHA>LW). Moreover, extracellular polymeric substances (EPS; aquagenic origin) stabilized lipoic acid-coated AgNPs more effectively than Suwannee River Humic Acids (SRHA; pedogenic origin), showing that DOM nature has to be also considered for improved understanding the AgNP stability in aquatic environment. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Antibacterial Activity of Polyaniline Coated Silver Nanoparticles Synthesized from Piper Betle Leaves Extract.

    Science.gov (United States)

    Mamun Or Rashida, Md; Shafiul Islam, Md; Azizul Haque, Md; Arifur Rahman, Md; Tanvir Hossain, Md; Abdul Hamid, Md

    2016-01-01

    Plants or natural resources have been found to be a good alternative method for nanoparticles synthesis. In this study, polyaniline coated silver nanoparticles (AgNPs) synthesized from Piper betle leaves extract were investigated for their antibacterial activity. Silver nanoparticles were prepared from the reduction of silver nitrate and NaBH4 was used as reducing agent. Silver nanoparticles and extracts were mixed thoroughly and then coated by polyaniline. Prepared nanoparticles were characterized by Visual inspection, Ultraviolet-visible spectroscopy (UV), Fourier transform infrared Spectroscopy (FT-IR), Transmission Electron Microscopy (TEM) techniques. Antibacterial activities of the synthesized silver nanoparticles were tested against Staphylococcus aureus ATCC 25923, Salmonella typhi ATCC 14028, Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853. UV-Vis spectrum of reaction mixture showed strong absorption peak with centering at 400 nm. The FT-IR results imply that Ag-NPs were successfully synthesized and capped with bio-compounds present in P. betle. TEM image showed that Ag-NPs formed were well dispersed with a spherical structures and particle size ranging from 10 to 30 nm. The result revealed that Ag-Extract NPs showed 32.78±0.64 mm zone of inhibition against S. aureus, whereas norfloxacin (positive control) showed maximum 32.15±0.40 mm zone of inhibition for S. aureus. Again, maximum zone of inhibition 29.55±0.45 mm was found for S. typhi, 27.12±0.38 mm for E. coli and 21.95±0.45 mm for P. aeruginosa. The results obtained by this study can't be directly extrapolated to human; so further studies should be undertaken to established the strong antimicrobial activity of Ag-Extract NPs for drug development program.

  18. Characterisation of bioaccumulation dynamics of three differently coated silver nanoparticles and aqueous silver in a simple freshwater food chain

    DEFF Research Database (Denmark)

    Kalman, Judit; Paul, Kai B.; Khan, Farhan R.

    2015-01-01

    This study investigated the bioaccumulation dynamics of silver nanoparticles (Ag NPs) with different coatings (polyvinyl pyrrolidone, polyethylene glycol and citrate), in comparison with aqueous Ag (added as AgNO3), in a simplified freshwater food chain comprising the green alga Chlorella vulgaris...... and the crustacean Daphnia magna. Algal uptake rate constants (ku) and membrane transport characteristics (binding site density, transporter affinity and strength of binding) were determined after exposing algae to a range of either aqueous Ag or Ag NP concentrations. In general, higher ku values were related...... to higher toxicity in the algae. Transmission electron microscopy images were used to investigate the internalisation of Ag NPs in algal cells following exposure to low concentrations for 72 h (mimicking inhibition tests) or high concentrations for 4 h (mimicking preparation for daphnia dietary exposure...

  19. Transport of citrate-coated silver nanoparticles in unsaturated sand

    Science.gov (United States)

    Kumahor, Samuel; Hron, Pavel; Metreveli, George; Schaumann, Gabriele; Vogel, Hans-Jörg

    2015-04-01

    Chemical factors and physical constraints lead to coupled effects during particle transport in unsaturated porous media. Unlike for saturated transport, studies on unsaturated transport as typical for soil are currently scarce. We investigated the mobility of citrate-coated Ag NPs in unsaturated sand (grain diameter: 0.1-0.3 mm). For three flux rates and a given pore-water ionic strength (1 mM KNO3), the citrate-coated Ag NPs were less mobile at pH = 5 compared to pH = 9. The classic Derjaguin-Landau-Verwey-Overbeek (DLVO) theory suggests unfavorable deposition conditions at both, the air-water interface and solid-water interface. Breakthrough curves measured under quasi-steady state unsaturated flow showed retardation of the citrate-coated Ag NPs compared to inert solute (KBr). After flushing with nanoparticle-free 1 mM KNO3 solution (pH-adjusted), retention was much lower in deeper depths compared to the surface where the particles entered the flow field. The results show a non-linear dependence of nanoparticle (NP) mobility on flux rate and water content. Especially the observed retardation similar to equilibrium sorption is in contrast to observations under saturated flow conditions. A convection-dispersion and reaction model that combines a reversible equilibrium process and a non-equilibrium interaction process reproduced the measured breakthrough curves reasonably well. From comparison between saturated and unsaturated experiments we conclude that the air-water interface is responsible for the reversible equilibrium process while the water-solid interface accounts for irreversible soption.

  20. In Vitro Assessment of the Antibacterial Potential of Silver Nano-Coatings on Cotton Gauzes for Prevention of Wound Infections

    Directory of Open Access Journals (Sweden)

    Federica Paladini

    2016-05-01

    Full Text Available Multidrug-resistant organisms are increasingly implicated in acute and chronic wound infections, thus compromising the chance of therapeutic options. The resistance to conventional antibiotics demonstrated by some bacterial strains has encouraged new approaches for the prevention of infections in wounds and burns, among them the use of silver compounds and nanocrystalline silver. Recently, silver wound dressings have become widely accepted in wound healing centers and are commercially available. In this work, novel antibacterial wound dressings have been developed through a silver deposition technology based on the photochemical synthesis of silver nanoparticles. The devices obtained are completely natural and the silver coatings are characterized by an excellent adhesion without the use of any binder. The silver-treated cotton gauzes were characterized through scanning electron microscopy (SEM and thermo-gravimetric analysis (TGA in order to verify the distribution and the dimension of the silver particles on the cotton fibers. The effectiveness of the silver-treated gauzes in reducing the bacterial growth and biofilm proliferation has been demonstrated through agar diffusion tests, bacterial enumeration test, biofilm quantification tests, fluorescence and SEM microscopy. Moreover, potential cytotoxicity of the silver coating was evaluated through 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide colorimetric assay (MTT and the extract method on fibroblasts and keratinocytes. Inductively coupled plasma mass spectrometry (ICP-MS was performed in order to determine the silver release in different media and to relate the results to the biological characterization. All the results obtained were compared with plain gauzes as a negative control, as well as gauzes treated with a higher silver percentage as a positive control.

  1. A Comparative Study on the Conductive Properties of Coated and Printed Silver Layers on a Paper Substrate

    Science.gov (United States)

    Nash, Cian; Spiesschaert, Yann; Amarandei, George; Stoeva, Zlatka; Tomov, Rumen I.; Tonchev, Dan; van Driessche, Isabel; Glowacki, Bartlomiej Andrzej

    2015-01-01

    The industrial sector of flexible printed electronics has shown a dynamic growth in the last decades. Therefore, demand for new inks, coatings and printing methods leading to improved performances of the electronic components at room temperature is also increasing. Here, we present a study on the conductive properties of silver layers obtained by different coating and printing methods. The results obtained proved that drop-on-demand inkjet printing of water-based inks containing micron-sized silver flakes with narrow-size distribution is a feasible method for in situ fabrication of conductive silver coatings that does not require additional heat treatment. A rigorous optimization Taguchi experiment was carried out considering the major process parameters. This experiment showed that the printing pressure was the dominant factor defining the quality of the printed coatings and tracks.

  2. Novel microcalorimetric assay for antibacterial activity of implant coatings: The cases of silver-doped hydroxyapatite and calcium hydroxide.

    Science.gov (United States)

    Braissant, Olivier; Chavanne, Philippe; de Wild, Michael; Pieles, Uwe; Stevanovic, Sabrina; Schumacher, Ralf; Straumann, Lukas; Wirz, Dieter; Gruner, Philipp; Bachmann, Alexander; Bonkat, Gernot

    2015-08-01

    Biomaterials with antimicrobial properties are now commonly used in different clinical specialties including orthopedics, endodontic, and traumatology. As a result, assessing the antimicrobial effect of coatings applied on implants is of critical importance. In this study, we demonstrate that isothermal microcalorimetry (IMC) can be used for monitoring bacterial growth and biofilm formation at the surface of such coatings and for determining their antimicrobial effects. The antibacterial effects of silver doped hydroxyapatite (HA) and calcium hydroxide coatings on Staphylococcus epidermidis were determined with a minimal workload. Using the Gompertz growth model we determined biofilm growth rates close to those values reported in the literature. Furthermore, we were able to estimate the reduction in the bacterial inocula originally applied at the surface of the coatings. Therefore, in addition to monitoring the antimicrobial effect of silver doped HA and calcium hydroxide coatings, we also demonstrate that IMC might be a valuable tool for assessing such antimicrobial properties of implant coatings at a minimal workload.

  3. Non-contact assessment of electrical performance for rapidly sintered nanoparticle silver coatings through colorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Cherrington, M.; Claypole, T.C.; Gethin, D.T. [Welsh Centre for Printing and Coating, College of Engineering, Swansea University, Singleton Park, Swansea, SA2 8PP (United Kingdom); Worsley, D.A. [SPECIFIC, College of Engineering, Swansea University, Baglan Bay Innovation Centre, Central Avenue, Baglan Energy Park, Port Talbot, SA12 7AX (United Kingdom); Deganello, D., E-mail: d.deganello@swansea.ac.uk [Welsh Centre for Printing and Coating, College of Engineering, Swansea University, Singleton Park, Swansea, SA2 8PP (United Kingdom)

    2012-11-01

    The color change during the ultrafast near-infrared sintering process of a nanoparticle silver ink has been correlated to its electrical performance through colorimetry using the CIELAB industry standard. Nanoparticle silver ink films, deposited over a flexible polyethylene terephthalate substrate, presented significant shifting in the a* and b* color coordinates during sintering, exhibiting the best conductivity with an a* coordinate of approximately 0 and a b* coordinate of approximately + 10. This color change has been associated with the Lorenz-Mie theory of electromagnetic scattering. This indirect measurement technique is potentially a breakthrough technology for fast in-line non-contact characterization of the drying and sintering process of nanoparticle conductive inks for use in large area roll-to-roll processing of printed electronics. - Highlights: Black-Right-Pointing-Pointer Color change of a nanoparticle silver coating was measured during sintering Black-Right-Pointing-Pointer Color change was correlated to the electrical performance of the coating. Black-Right-Pointing-Pointer Potential in-line non-contact measurement method for roll-to-roll printed electronics.

  4. Effect of silver nanoparticle coatings on mycobacterial biofilm attachment and growth: Implications for ceramic water filters

    Science.gov (United States)

    Larimer, Curtis James

    Silver is a natural, broad-spectrum antibacterial metal and its toxicity can be enhanced when surface area is maximized. As a result, silver nanoparticles (AgNP) have been investigated for use in novel water treatment technologies. The hypothesis of this work is that deposited AgNPs can enhance water treatment technologies by inhibiting growth of planktonic bacteria and biofilms. This was investigated by evaluating the antibacterial efficacy of AgNPs both in solution and as deposited on surfaces. AgNPs were found to be toxic to three species of environmental mycobacteria, M. smegmatis, M. avium, and M. marinum and the level of susceptibility varied widely, probably owing to the varying levels of silver that each species is exposed to in its natural environment. When cultured in a AgNP enriched environment M. smegmatis developed resistance to the toxic effects of both the nanoparticles and silver ions. The resistant mutant was as viable as the unmodified strain and was also resistant to antibiotic isoniazid. However, the strain was more susceptible to other toxic metal ions from ZnSO4 and CuSO4. AgNPs were deposited on silicon wafer substrates by vertical colloidal deposition (VCD). Manipulating deposition speed and also concentration of AgNPs in the depositing liquid led to a range of AgNP coatings with distinctive deposition lines perpendicular to the motion of the meniscus. Experimental results for areal coverage, which was measured from SEM images of AgNP coatings, were compared to Diao's theory of VCD but did not show agreement due to a stick-slip mechanism that is not accounted for by the theory. Durability of AgNP coatings is critical for antibacterial efficacy and to mitigate the risks of exposing the environment to nanomaterials and it was measured by exposing AgNP coatings to liquid flow in a flow cell. Durability was improved by modifying processing to include a heat treatment after deposition. Finally, the antibiofilm efficacy of deposited AgNPs was

  5. Mechanical and microstructural characterization of aluminum reinforced with carbon-coated silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Sanchez, R. [Centro de Investigacion en Materiales Avanzados (CIMAV), Miguel de Cervantes No. 120, CP 31109, Chihuahua (Mexico)]. E-mail: roberto.martinez@cimav.edu.mx; Reyes-Gasga, J. [Instituto de Fisica, UNAM, Apartado Postal 20-364, 01000 Mexico, D.F. (Mexico); Caudillo, R. [Texas Materials Institute and Chemical Engineering Department, University of Texas at Austin, Austin, TX 78712-1063 (United States); Garcia-Gutierrez, D.I. [Texas Materials Institute and Chemical Engineering Department, University of Texas at Austin, Austin, TX 78712-1063 (United States); Marquez-Lucero, A. [Centro de Investigacion en Materiales Avanzados (CIMAV), Miguel de Cervantes No. 120, CP 31109, Chihuahua (Mexico); Estrada-Guel, I. [Centro de Investigacion en Materiales Avanzados (CIMAV), Miguel de Cervantes No. 120, CP 31109, Chihuahua (Mexico); Mendoza-Ruiz, D.C. [Centro de Investigacion en Materiales Avanzados (CIMAV), Miguel de Cervantes No. 120, CP 31109, Chihuahua (Mexico); Jose Yacaman, M. [Texas Materials Institute and Chemical Engineering Department, University of Texas at Austin, Austin, TX 78712-1063 (United States)

    2007-07-12

    Composites of pure aluminum with carbon-coated silver nanoparticles (Ag-C NP) of 10 nm in size were prepared by the mechanical milling process. Transmission electron microscopy showed that the Ag-C NP are homogeneously dispersed into the Al matrix, silver nanoparticles do not coalesce, grow or dissolve in the aluminum matrix due the carbon shell. The values of yield strength ({sigma} {sub y}), maximum strength ({sigma} {sub max}) and micro-hardness Vickers (HVN) of the composites were evaluated and reported as a function of Ag-C NP content. It has been found that the introduction of this type of particles in aluminum strengthen it, increasing all the previous parameters.

  6. Characterization and antimicrobial performance of nano silver coatings on leather materials.

    Science.gov (United States)

    Lkhagvajav, N; Koizhaiganova, M; Yasa, I; Çelik, E; Sari, Ö

    2015-03-01

    In this study, the characterization and the antimicrobial properties of nano silver (nAg) coating on leather were investigated. For this purpose, turbidity, viscosity and pH of nAg solutions prepared by the sol-gel method were measured. The formation of films from these solutions was characterized according to temperature by Differential Thermal Analysis-Thermogravimetry (DTA-TG) equipment. The surface morphology of treated leathers was observed using Scanning Electron Microscopy (SEM). The antimicrobial performance of nAg coatings on leather materials to the test microorganisms as Escherichia coli , Staphylococcus aureus , Candida albicans and Aspergillius niger was evaluated by the application of qualitative (Agar overlay method) and quantitative (percentage of microbial reduction) tests. According to qualitative test results it was found that 20 μg/cm (2) and higher concentrations of nAg on the leather samples were effective against all microorganisms tested. Moreover, quantitative test results showed that leather samples treated with 20 μg/cm (2) of nAg demonstrated the highest antibacterial activity against E. coli with 99.25% bacterium removal, whereas a 10 μg/cm (2) concentration of nAg on leather was enough to exhibit the excellent percentage reduction against S. aureus of 99.91%. The results are promising for the use of colloidal nano silver solution on lining leather as antimicrobial coating.

  7. Characterization and antimicrobial performance of nano silver coatings on leather materials

    Directory of Open Access Journals (Sweden)

    N. Lkhagvajav

    2015-03-01

    Full Text Available In this study, the characterization and the antimicrobial properties of nano silver (nAg coating on leather were investigated. For this purpose, turbidity, viscosity and pH of nAg solutions prepared by the sol-gel method were measured. The formation of films from these solutions was characterized according to temperature by Differential Thermal Analysis-Thermogravimetry (DTA-TG equipment. The surface morphology of treated leathers was observed using Scanning Electron Microscopy (SEM. The antimicrobial performance of nAg coatings on leather materials to the test microorganisms as Escherichia coli, Staphylococcus aureus, Candida albicans and Aspergillius niger was evaluated by the application of qualitative (Agar overlay method and quantitative (percentage of microbial reduction tests. According to qualitative test results it was found that 20 μg/cm2 and higher concentrations of nAg on the leather samples were effective against all microorganisms tested. Moreover, quantitative test results showed that leather samples treated with 20 μg/cm2 of nAg demonstrated the highest antibacterial activity against E. coli with 99.25% bacterium removal, whereas a 10 μg/cm2 concentration of nAg on leather was enough to exhibit the excellent percentage reduction against S. aureus of 99.91%. The results are promising for the use of colloidal nano silver solution on lining leather as antimicrobial coating.

  8. Organic matter induced mobilization of polymer-coated silver nanoparticles from water-saturated sand.

    Science.gov (United States)

    Yang, Xinyao; Yin, Ziyi; Chen, Fangmin; Hu, Jingjing; Yang, Yuesuo

    2015-10-01

    Mobilization of polymer-coated silver nanoparticles (AgNPs) by anionic surfactant (sodium dodecylbenzenesulphonate: SDBS), amino acid derivative (N-acetylcysteine: NAC), and chelate (ethylenediaminetetraacetic acid: EDTA) in water-saturated sand medium was explored based on carefully designed column tests. Exposure experiments monitoring the size evolution of polyvinylpyrrolidone (PVP) coated AgNPs in organic solutions confirm the capacity of SDBS, NAC and EDTA to partly displace PVP. Single Pulse Column Experiment (SPCE) results show both the PVP polymer and the silver core controlled AgNP deposition while the effect of the PVP was dominant. Results of Co-injected Pulse Column Experiments (CPCEs) where AgNP and SDBS or NAC were co-injected into the column following a very short mixing (organic would mobilize irreversibly deposited particles from the uncoated sand, while surface charge modification by adsorbed NAC was identified as a potential mobilizing mechanism for AgNP from the iron-oxide-coated sand. Triple Pulse Column Experiment (TPCE) results confirm that such a charging effect of the adsorbed organic molecules may enable SDBS and NAC to mobilize AgNPs from the iron-oxide-coated sands. TPCE results with five distinct levels of SDBS indicate that concentration-stimulated change in the SDBS format from an individual to a micelle significantly increased the mobilizing efficiency and site blockage of SDBS. Although being an electrolyte, EDTA did not mobilize AgNPs, as the case with SDBS or NAC, as it dissolved the iron oxides which in turn prevented EDTA adsorption on sand. The findings have implications for better understanding the behavior of polymer-coated nanoparticles in organic-presented groundwater systems, i.e., detachment-associated uncertainty in exposure prediction of the nanomaterials.

  9. Early investigation of silver-coated Silzone heart valves prosthesis in 126 patients.

    Science.gov (United States)

    Auer, J; Berent, R; Ng, C K; Punzengruber, C; Mayr, H; Lassnig, E; Schwarz, C; Puschmann, R; Hartl, P; Eber, B

    2001-11-01

    Permanent silver (Silzone) coating of the sewing cuff of St. Jude Medical prosthetic heart valves may reduce the rate of prosthetic valve endocarditis (PVE). However, the incidence of paravalvular leaks and stroke in patients after implantation of Silzone-coated heart valve prostheses is largely unknown. Complications were analyzed among 126 consecutive patients (78 males, 48 females; mean age 64.7 years; range: 40-80 years) who received Silzone-coated prostheses at our institution between February 1998 and December 1999. Among patients, 94 had aortic valve replacement, 29 mitral valve replacement, and three had aortic and mitral valve replacement. Concomitant cardiac procedures (mainly coronary bypass) were performed in 47 patients (37.3%). Hospital mortality was 1.6% (2/126) and freedom from valve-related mortality 99.2+/-0.9%. Total follow up was 137.4 patient-years, and 98.4% complete. Strokes or transitory ischemic attacks (TIAs) occurred in four cases (two strokes, two TIAs; stroke rate 1.5%/year; 95% CI 0.4-2.6%/year; stroke+TIA rate 3%/year; 95% CI 0.4-5.25%/year). There was no case of prosthetic valve dysfunction or PVE. Freedom from reoperation due to procedure-associated complications was 97.6% (one aortic dissection, two major bleeds). Paravalvular leak was detected in 19 cases, and graded trivial or mild in 17 cases (11 grade 0-I, six grade I), and moderate in two cases (grade I-II in one, grade II in one). No patient needed reoperation due to paravalvular leak. Left ventricular (LV) function was normal in 80 cases, but was impaired mildly in 20 cases, moderately in 16, and severely in eight. Bicycle exercise testing in 92 patients (73%) showed median exercise performance (81.4+/-23.9% of normal) after correction for age and weight. Cerebral magnetic resonance imaging was performed in 64 patients (50.8%); median MRI score was 2.0+/-1.8 according to a 12-scaled score system. The overall incidence of echocardiographic paravalvular leak graded more than

  10. Antimicrobial activity and cytocompatibility of silver nanoparticles coated catheters via a biomimetic surface functionalization strategy

    Directory of Open Access Journals (Sweden)

    Wu K

    2015-12-01

    Full Text Available Ke Wu,1 Yun Yang,2,3 Yanmei Zhang,2,3 Jiexi Deng,1 Changjian Lin2,31Department of Cardiology, The Affiliated Dongnan Hospital of Xiamen University, Zhangzhou, 2Department of Medical Materials, Beijing Medical Implant Engineering Research Center, Beijing Naton Technology Group, Beijing, 3State Key Laboratory of Physical Chemistry of Solid Surfaces, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, People’s Republic of ChinaAbstract: Catheter-related bloodstream infections are a significant problem in the clinic and may result in a serious infection. Here, we developed a facile and green procedure for buildup of silver nanoparticles (AgNPs on the central venous catheters (CVCs surface. Inspired by mussel adhesive proteins, dopamine was used to form a thin polydopamine layer and induce AgNPs formation without additional reductants or stabilizers. The chemical and physicochemical properties of AgNPs coated CVCs were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and water contact angle. The Staphylococcus aureus culture experiment was used to study the antibacterial properties. The cytocompatibility was assessed by water soluble tetrazolium salts (WST-1 assay, fluorescence staining, and scanning electron microscopy analysis. The results indicated that the CVCs surface was successfully coated with compact AgNPs. AgNPs were significantly well separated and spherical with a size of 30–50 nm. The density of AgNPs could be modulated by the concentration of silver nitrate solution. The antibacterial activity was dependent on the AgNPs dose. The high dose of AgNPs showed excellent antibacterial activity while associated with increased cytotoxicity. The appropriate density of AgNPs coated CVCs could exhibit improved biocompatibility and maintained evident sterilization effect. It is promising to design mussel-inspired silver releasing CVCs with both

  11. Fabrication of a rugged polymer-coated silver hollow fiber with a vitreous film for the infrared

    Science.gov (United States)

    Iwai, Katsumasa; Miyagi, Mitsunobu; Shi, Yi-Wei; Matsuura, Yuji

    2013-03-01

    A rugged hollow fiber is fabricated by liquid-phase coating techniques. A silica glass capillary is used as the substrate and a vitreous film is firstly coated on the inner surface of the capillary to protect the glass tube from moisture. This protective coating keeps the thin-wall glass tube away from damage due to the following silver plating process. On the protective coating, a silver film is deposited by the conventional mirror plating technique. Subsequently, a polymer film is coated on the silver film to reduce transmission loss by employing interference effect of the polymer film. Fabrication processes and transmission properties of the rugged polymer-coated silver hollow fiber were discussed. The loss for the 700-μm-bore size, 1-m-length hollow fiber was 2 dB under straight configuration, and 3.5 dB under the configuration of a 270 degree bending with a 15-mm bending radius at the wavelength of 2.94 μm.

  12. Transport of citrate-coated silver nanoparticles in unsaturated sand

    Energy Technology Data Exchange (ETDEWEB)

    Kumahor, Samuel K., E-mail: samuel.kumahor@ufz.de [Department of Soil Physics, Helmholtz Centre for Environmental Research–UFZ, Theodor-Lieser-Strasse 4, 06120 Halle-Saale (Germany); Hron, Pavel, E-mail: pavel.hron@iwr.uni-heidelberg.de [Interdisciplinary Center for Scientific Computing, University of Heidelberg, Im Neuenheimer Feld 368, Raum 422, 69120 Heidelberg (Germany); Metreveli, George, E-mail: metreveli@uni-landau.de [Universität Koblenz-Landau, Institute for Environmental Sciences, Group of Environmental and Soil Chemistry, Fortstr. 7, D-76829 Landau (Germany); Schaumann, Gabriele E., E-mail: schaumann@uni-landau.de [Universität Koblenz-Landau, Institute for Environmental Sciences, Group of Environmental and Soil Chemistry, Fortstr. 7, D-76829 Landau (Germany); Vogel, Hans-Jörg, E-mail: hans-joerg.vogel@ufz.de [Department of Soil Physics, Helmholtz Centre for Environmental Research–UFZ, Theodor-Lieser-Strasse 4, 06120 Halle-Saale (Germany); Institute of Soil Science and Plant Nutrition, Martin-Luther-University Halle-Wittenberg, Von-Seckendorff-Platz 3, 06120 Halle-Saale (Germany)

    2015-12-01

    Chemical factors and physical constraints lead to coupled effects during particle transport in unsaturated porous media. Studies on unsaturated transport as typical for soils are currently scarce. In unsaturated porous media, particle mobility is determined by the existence of an air–water interface in addition to a solid–water interface. To this end, we measured breakthrough curves and retention profiles of citrate-coated Ag nanoparticles in unsaturated sand at two pH values (5 and 9) and three different flow rates corresponding to different water contents with 1 mM KNO{sub 3} as background electrolyte. The classical DLVO theory suggests unfavorable deposition conditions at the air–water and solid–water interfaces. The breakthrough curves indicate modification in curve shapes and retardation of nanoparticles compared to inert solute. Retention profiles show sensitivity to flow rate and pH and this ranged from almost no retention for the highest flow rate at pH = 9 to almost complete retention for the lowest flow rate at pH = 5. Modeling of the breakthrough curves, thus, required coupling two parallel processes: a kinetically controlled attachment process far from equilibrium, responsible for the shape modification, and an equilibrium sorption, responsible for particle retardation. The non-equilibrium process and equilibrium sorption are suggested to relate to the solid–water and air–water interfaces, respectively. This is supported by the DLVO model extended for hydrophobic interactions which suggests reversible attachment, characterized by a secondary minimum (depth 3–5 kT) and a repulsive barrier at the air–water interface. In contrast, the solid–water interface is characterized by a significant repulsive barrier and the absence of a secondary minimum suggesting kinetically controlled and non-equilibrium interaction. This study provides new insights into particle transport in unsaturated porous media and offers a model concept representing the

  13. Smooth-surface silver nanowire electrode with high conductivity and transparency on functional layer coated flexible film

    Energy Technology Data Exchange (ETDEWEB)

    Lee, So Hee; Lim, Sooman; Kim, Haekyoung, E-mail: hkkim@ynu.ac.kr

    2015-08-31

    Transparent conductive electrode (TCE) with silver nanowires has been widely studied as an alternative of indium tin oxide for flexible electronic or optical devices such as organic light-emitting diodes, and solar cells. However, it has an issue of surface roughness due to nanowire's intrinsic properties. Here, to achieve a smooth electrode with high conductivity and transmittance on polyethylene terephthalate (PET) substrates, a functional layer of poly(N-vinylpyrrolidone) (PVP) is utilized with a mechanical transfer process. The silver nanowire electrode on PVP-coated PET with low surface roughness of 9 nm exhibits the low sheet resistance of 18 Ω □{sup −1} and high transmittance of 87.6%. It is produced by transferring the silver nanowire electrode spin-coated on the glass to PVP-coated PET using a pressure of 10 MPa for 10 min. Silver nanowire electrode on PVP-coated PET demonstrates the stable sheet resistance of 18 Ω □{sup −1} after the mechanical taping test due to strong adhesion between PVP functional layer and silver nanowires. Smooth TCE with silver nanowires could be proposed as a transparent electrode for flexible electronic or optical devices, which consist of thin electrical active layers on TCE. - Highlights: • Silver nanowire (Ag NWs) transparent electrodes were fabricated on flexible film. • Flexible film was coated with poly N-vinylpyrrolidone (PVP). • PVP layer plays roles as an adhesive layer and matrix in electrode. • Ag NWs electrode exhibited with low surface roughness of 9 nm. • Ag NWs electrode has a low resistance (18 Ω ☐{sup −1}) and high transmittance (87.6%)

  14. New antimicrobial and biocompatible implant coating with synergic silver-vancomycin conjugate action.

    Science.gov (United States)

    Varisco, Massimo; Khanna, Nina; Brunetto, Priscilla S; Fromm, Katharina M

    2014-06-01

    Materials foreign to the body are used ever more frequently, as increasing numbers of patients require implants. As a consequence, the numbers of implant-related infections have grown as well, and with increasing resistance. Treatments often fail; thus, new antibacterial coating strategies are being developed by scientists to avoid, or at least strongly reduce, bacterial adhesion to implant surfaces. In this study, we focused on producing a self-protective coating combining silver(I) ions and a vancomycin-derived molecule, intelligent pyridinate vancomycin (IPV), with a synergetic and effective action against bacteria. These Ag(I) -IPV conjugate-coated surfaces are well characterized and exhibit strong bactericidal activity in vitro against Staphylococci strains. Furthermore, the released quantities of both drugs from the coated surfaces do not affect their biocompatibility and soft tissue integration. These newly developed Ag(I) -IPV conjugate coatings thus represent a possible and efficient protection method against bacterial adhesion and biofilm formation during and after implant surgery.

  15. Plasmon-enhanced refractometry using silver nanowire coatings on tilted fibre Bragg gratings.

    Science.gov (United States)

    Bialiayeu, A; Bottomley, A; Prezgot, D; Ianoul, A; Albert, J

    2012-11-09

    A novel technique for increasing the sensitivity of tilted fibre Bragg grating (TFBG) based refractometers is presented. The TFBG sensor was coated with chemically synthesized silver nanowires ~100 nm in diameter and several micrometres in length. A 3.5-fold increase in sensor sensitivity was obtained relative to the uncoated TFBG sensor. This increase is associated with the excitation of surface plasmons by orthogonally polarized fibre cladding modes at wavelengths near 1.5 μm. Refractometric information is extracted from the sensor via the strong polarization dependence of the grating resonances using a Jones matrix analysis of the transmission spectrum of the fibre.

  16. Spray coated silver nanowires as transparent electrodes in OPVs for Building Integrated Photovoltaics applications

    OpenAIRE

    Ding, Ziqian; Stoichkov, Vasil; Horie, Masaki; Brousseau, Emmanuel Bruno Jean-Paul; Kettle, Jeffrey

    2016-01-01

    The application of spray coated silver nanowires (AgNWs) onto OPVs for building Integrated Photovoltaics (BIPVs) is demonstrated. By using AgNWs with PEDOT:PSS, a transparent conductive layer was demonstrated on top of an P3HT:PCBM active layer with a sheet resistance of 30 Ω/⎕ for 90% transparency. This has been applied to two separate configurations; semi-transparent OPVs for solar glazing applications and OPVs onto an opaque substrate, namely steel. For the latter, a novel technique to pla...

  17. A novel hydroxyapatite film coated with ionic silver via inositol hexaphosphate chelation prevents implant-associated infection

    Science.gov (United States)

    Funao, Haruki; Nagai, Shigenori; Sasaki, Aya; Hoshikawa, Tomoyuki; Tsuji, Takashi; Okada, Yasunori; Koyasu, Shigeo; Toyama, Yoshiaki; Nakamura, Masaya; Aizawa, Mamoru; Matsumoto, Morio; Ishii, Ken

    2016-03-01

    Various silver-coated implants have been developed to prevent implant-associated infections, and have shown dramatic effects in vitro. However, the in vivo results have been inconsistent. Recent in vitro studies showed that silver exerts antibacterial activity by mediating the generation of reactive oxygen species in the presence of oxygen. To maintain its antibacterial activity in vivo, the silver should remain in an ionic state and be stably bound to the implant surface. Here, we developed a novel bacteria-resistant hydroxyapatite film in which ionic silver is immobilized via inositol hexaphosphate chelation using a low-heat immersion process. This bacteria-resistant coating demonstrated significant antibacterial activity both in vitro and in vivo. In a murine bioluminescent osteomyelitis model, no bacteria were detectable 21 days after inoculation with S. aureus and placement of this implant. Serum interleukin-6 was elevated in the acute phase in this model, but it was significantly lower in the ionic-silver group than the control group on day 2. Serum C-reactive protein remained significantly higher in the control group than the ionic-silver group on day 14. Because this coating is produced by a low-heat immersion process, it can be applied to complex structures of various materials, to provide significant protection against implant-associated infections.

  18. In vitro Biocompatibility of New Silver(I Coordination Compound Coated-Surfaces for Dental Implant Applications

    Directory of Open Access Journals (Sweden)

    Priscilla S. Brunetto

    2011-01-01

    Full Text Available Biofilm formation on implant materials causes a common problem: resistance to aggressive pharmacological agents as well as host defenses. Therefore, to reduce bacterial adhesion to implant surfaces we propose to use silver(I coordination networks as it is known that silver is the most powerful antimicrobial inorganic agent. As a model surface, self-assembled monolayers (SAMs on gold Au(111 was used to permit permanent attachment of our silver(I coordination networks. The surface coatings showed typical nano-structured surfaces with a good biocompatibility for soft-tissue integration with fibroblast cells.

  19. The effect of honey-coated bandages compared with silver-coated bandages on treatment of malignant wounds - a randomized study

    DEFF Research Database (Denmark)

    Lund-Nielsen, Betina; Adamsen, Lis; Kolmos, Hans Jørn

    2011-01-01

    Malignant wounds (MWs) occur in 5-10% of all cancer patients. Malodor and exudation are the most common side effects. The aim was to determine the influence of honey-coated compared with silver-coated bandages on treatment of MWs. Patients were randomly selected to enter either group A (honey......-coated bandages) or group B (silver-coated bandages). Parameters were the following: wound size, cleanliness, malodor, exudation, and wound pain. Digital photographs, visual analog scales (VAS), and wound morphology registration were used for measurement at baseline and following the 4-week intervention. Sixty......-nine patients with MWs and advanced cancer, aged 47-90 (median 65.6), were included. No statistically significant difference was noted between the groups with respect to wound size, degree of cleanliness, exudation, malodor, and wound pain. There was a median decrease in wound size of 15 cm(2) and 8 cm(2...

  20. Chitosan-coated anisotropic silver nanoparticles as a SERS substrate for single-molecule detection

    Science.gov (United States)

    Potara, Monica; Baia, Monica; Farcau, Cosmin; Astilean, Simion

    2012-02-01

    Surface-enhanced Raman spectroscopy (SERS) is a technique that has become widely used for identifying and providing structural information about molecular species in low concentration. There is an ongoing interest in finding optimum particle size, shape and spatial distribution for optimizing the SERS substrates and pushing the sensitivity toward the single-molecule detection limit. This work reports the design of a novel, biocompatible SERS substrate based on small clusters of anisotropic silver nanoparticles embedded in a film of chitosan biopolymer. The SERS efficiency of the biocompatible film is assessed by employing Raman imaging and spectroscopy of adenine, a significant biological molecule. By combining atomic force microscopy with SERS imaging we find that the chitosan matrix enables the formation of small clusters of silver nanoparticles, with junctions and gaps that greatly enhance the Raman intensities of the adsorbed molecules. The study demonstrates that chitosan-coated anisotropic silver nanoparticle clusters are sensitive enough to be implemented as effective plasmonic substrates for SERS detection of nonresonant analytes at the single-molecule level.

  1. Biobased silver nanocolloid coating on silk fibers for prevention of post-surgical wound infections

    Directory of Open Access Journals (Sweden)

    Dhas SP

    2015-10-01

    Full Text Available Sindhu Priya Dhas, Suruthi Anbarasan, Amitava Mukherjee, Natarajan Chandrasekaran Center for Nanobiotechnology, VIT University, Vellore, India Abstract: Bombyx mori silk fibers are an important biomaterial and are used in surgical sutures due to their remarkable biocompatibility. The major drawback to the application of biomaterials is the risk of bacterial invasion, leading to clinical complications. We have developed an easy and cost-effective method for fabrication of antibacterial silk fibers loaded with silver nanoparticles (AgNPs by an in situ and ex situ process using an aqueous extract of Rhizophora apiculata leaf. Scanning electron microscopy revealed that well dispersed nanoparticles impregnated the silk fibers both in situ and ex situ. The crystalline nature of the AgNPs in the silk fibers was demonstrated by X-ray diffraction. The thermal and mechanical properties of the silk fibers were enhanced after they were impregnated with AgNPs. The silver-coated silk fibers fabricated by the in situ and ex situ method exhibited more than 90% inhibition against Pseudomonas aeruginosa and Staphylococcus aureus. Silk fibers doped with AgNPs were found to be biocompatible with 3T3 fibroblasts. The results obtained represent an important advance towards the clinical application of biocompatible AgNP-loaded silk fibers for prevention of surgical wound infections. Keywords: silk fibers, silver nanoparticles, antibacterial activity, wound infections, cytotoxicity, 3T3 fibroblast cells

  2. Microstructure and cytotoxicity evaluation of duplex-treated silver-containing antibacterial TiO{sub 2} coatings

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiangyu; Wu, Haibo; Geng, Zhenhua; Huang, Xiaobo; Hang, Ruiqiang; Ma, Yong; Yao, Xiaohong; Tang, Bin, E-mail: tangbin6405@sina.com

    2014-12-01

    Implant-related infection is one of the most common and serious complications associated with biomedical implantation. To prevent bacterial adhesion, a series of porous TiO{sub 2} coatings with different concentrations of silver (designated as M0, M1, M2 and M3) were prepared on pure titanium substrates by a duplex-treatment technique combining magnetron sputtering with micro-arc oxidation. All coatings are porous with pore size less than 5 μm and the concentrations of silver in the M0, M1, M2 and M3 are 0, 0.95, 1.36 and 1.93 wt.%, respectively. Silver is found to be distributed throughout the thickness of the coatings by scanning electron microscopy. The release of silver from the TiO{sub 2} coatings was confirmed by an inductively-coupled plasma mass spectroscopy. The antibacterial effects of these coatings were tested against Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli), and the cytotoxicity was evaluated using the mouse pre-osteoblast cells. The results indicate that the antibacterial activities of TiO{sub 2} coatings are greatly improved due to the incorporation of silver. No cytotoxic effect is found for the M1 surfaces from the observation of pre-osteoblast cell by MTT assay and fluorescence microscopy. Although the M2 and M3 coatings appeared to be toxic for pre-osteoblast cells after 1 day in culture, the cell viability on M2 and M3 surfaces was greatly raised after culturing for 2 days. Our results suggested that the TiO{sub 2} coatings incorporated with an optimum amount of silver can possess excellent antibacterial activities without cytotoxic effect, which has promising applications in biomedical devices. - Highlights: • Porous TiO{sub 2} coatings with various concentration of Ag on titanium were prepared. • Ag element was distributed throughout the thickness of the coatings. • The antibacterial activities were greatly improved due to the incorporation of Ag. • The release amounts of Ag were

  3. Mechanisms of antibacterial activity and stability of silver nanoparticles grown on magnetron sputtered TiO2 coatings

    Indian Academy of Sciences (India)

    K Zawadzka; A Kisielewska; I Piwoński; K Kądzioła; A Felczak; S Różalska; N Wrońska; K Lisowska

    2016-02-01

    Nanomaterials with high stability and efficient antibacterial activity are of considerable interest. The preparation of silver nanoparticles (AgNPs) on titania coatings and their effective antibacterial activity against Staphylococcus aureus ATCC 6538 were reported. Titanium dioxide (TiO2) coatings with AgNPs were prepared on Si wafers using the reactive magnetron sputtering method. The surface topography of AgNPs/TiO2 coatings imaged using scanning electron microscopy revealed that the size and surface density of AgNPs grown by the photoreduction of silver ions were dependent on the concentration of AgNO3 in the primary solution and the time of TiO2 exposure to UV illumination. Evaluation of the antimicrobial properties and surface analysis before and after the biological test of AgNPs/TiO2 coatings indicates their high antimicrobial stability and durability. Furthermore, the interdependence between the concentration of released silver and bacterial growth inhibition was demonstrated. In addition, direct contact killing and released silver-mediated killing have been proposed as a bactericidal mechanism of action of tested coatings with AgNPs.

  4. Gold-coated silver dendrites as SERS substrates with an improved lifetime.

    Science.gov (United States)

    Gutés, Albert; Maboudian, Roya; Carraro, Carlo

    2012-12-21

    Nanostructured silver is known to yield the highest signal-enhancement factors in surface-enhanced Raman spectroscopy, but its low chemical stability toward oxidation presents a challenge in the realization of Ag-based SERS substrates with long operating lifetimes. Here, a study of the long-term stability of silver dendrites as SERS substrates is reported. SERS spectra of 1,2-benzenedithiol monolayers on Ag dendrites, acquired over a period of time in excess of 1 year, shows appreciable degradation with time. However, no degradation is observed in the spectra of monolayers deposited on Ag dendrites that were coated with a monolayer-thin Au film deposited by an immersion plating process. X-ray photoelectron spectra confirm the oxidation of the uncoated Ag dendrites whereas no chemical changes are detected in the Au-coated ones. These results suggest that the galvanic displacement of Au on preformed Ag nanostructures provides a suitable route to producing SERS-active substrates with long operating and/or shelf lifetimes.

  5. Properties of polyacrylic acid-coated silver nanoparticle ink for inkjet printing conductive tracks on paper with high conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Qijin [Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201 (China); Shen, Wenfeng, E-mail: wfshen@nimte.ac.cn [Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201 (China); Xu, Qingsong [Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201 (China); Tan, Ruiqin [Faculty of Information Science and Engineering, Ningbo University, Ningbo, Zhejiang 315211 (China); Song, Weijie, E-mail: weijiesong@nimte.ac.cn [Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201 (China)

    2014-10-15

    Silver nanoparticles with a mean diameter of approximately 30 nm were synthesized by reduction of silver nitrate with triethanolamine in the presence of polyacrylic acid. Silver nanoparticle-based ink was prepared by dispersing silver nanoparticles into a mixture of water and ethylene glycol. The mechanism for the dispersion and aggregation of silver nanoparticles in ink is discussed. The strong electrostatic repulsions of the carboxylate anions of the adsorbed polyacrylic acid molecules disturbed the aggregation of metal particles in solutions with a high pH value (pH > 5). An inkjet printer was used to deposit this silver nanoparticle-based ink to form silver patterns on photo paper. The actual printing qualities of the silver tracks were then analyzed by variation of printing passes, sintering temperature and time. The results showed that sintering temperature and time are associated strongly with the conductivity of the inkjet-printed conductive patterns. The conductivity of printed patterns sintered at 150 °C increased to 2.1 × 10{sup 7} S m{sup −1}, which was approximately one third that of bulk silver. In addition, silver tracks on paper substrate also showed better electrical performance after folding. This study demonstrated that the resulting ink-jet printed patterns can be used as conductive tracks in flexible electronic devices. - Highlights: • An ink from silver nanoparticles coated with polyacrylic acid was prepared. • The ink was used for inkjet-printed tracks at varying printing parameters. • The conductivity of printed tracks sintered at 150 °C increased to 2.1 × 10{sup 7} S/m. • Mechanism for dispersion and aggregation of the nanoparticles in ink is discussed.

  6. Evaluation of Antibacterial Effects of Silver-Coated Stainless Steel Orthodontic Brackets

    Directory of Open Access Journals (Sweden)

    Valiollah Arash

    2016-08-01

    Full Text Available Objectives: White spots and enamel demineralization around orthodontic brackets are among the most important complications resulting from orthodontic treatments. Since the antibacterial properties of metals and metallic particles have been well documented, the aim of this study was to assess the antibacterial effect of stainless steel orthodontic brackets coated with silver (Ag particles.Materials and Methods: In this study, 40 standard metal brackets were divided into two groups of 20 cases and 20 controls. The brackets in the case group were coated with Ag particles using an electroplating method. Atomic force microscopy (AFM and scanning electron microscopy (SEM were used to assess the adequacy of the coating process. In addition, antibacterial tests, i.e., disk diffusion and direct contact tests were performed at three, six, 24and 48 hours, and 15 and 30 days using a Streptococcus mutans strain. The results were analyzed using Student’s t-test and repeated measures ANOVA.Conclusions: Brackets coated with Ag, via an electroplating method, exhibited antibacterial properties when placed in direct contact with Streptococcus mutans. This antibacterial effect persisted for 30 days after contact with the bacteria.

  7. Improving properties of Hanji by coating chitosan-silver nanoparticle solution.

    Science.gov (United States)

    Jung, Jeyoung; Raghavendra, Gownolla Malegowd; Kim, Dowan; Seo, Jongchul

    2016-12-01

    A chitosan-silver nanoparticle solution (CSNS) was applied as a coating material to Hanji (Korean traditional paper), and the properties of the coated paper were investigated as a function of the dilution ratio. The required CSNS was first prepared from AgNO3 (30mmol) by utilizing chitosan as a reducing and stabilizing agent via ultrasonication. The as-prepared CSNS was diluted to various ratios (undiluted, 1/10, 1/100, and 1/1000) and applied to Hanji by a dip-coating method. The tensile, burst, oil resistance, and antibacterial properties of the coated Hanji against Escherichia coli were evaluated. Among the various dilution ratios, the maximum level of dilution that can positively influence the tensile, burst, oil resistance, and antibacterial properties of Hanji was identified as 1/10, 1/100, 1/10 and 1/1000 of the pure CSNS, respectively. These findings are significant because a specific property of Hanji can be economically improved by changing the dilution ratio. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Cytotoxicity and antibacterial property of titanium alloy coated with silver nanoparticle-containing polyelectrolyte multilayer

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xinming [School of Materials Science and Engineering, Tianjin University, Tianjin, 300072 (China); Li, Zhaoyang [School of Materials Science and Engineering, Tianjin University, Tianjin, 300072 (China); Tianjin Key Laboratory of Composite and Functional Materials, Tianjin, 300072 (China); Yuan, Xubo [School of Materials Science and Engineering, Tianjin University, Tianjin, 300072 (China); Cui, Zhenduo [School of Materials Science and Engineering, Tianjin University, Tianjin, 300072 (China); Tianjin Key Laboratory of Composite and Functional Materials, Tianjin, 300072 (China); Bao, Huijing; Li, Xue; Liu, Yunde [School of Laboratory Medicine, Tianjin Medical University, Tianjin, 300203 (China); Yang, Xianjin, E-mail: xjyang@tju.edu.cn [School of Materials Science and Engineering, Tianjin University, Tianjin, 300072 (China); Tianjin Key Laboratory of Composite and Functional Materials, Tianjin, 300072 (China)

    2013-07-01

    Silver nanoparticle (AgNP) was incorporated into dopamine-modified alginate/chitosan (DAL/CHI) polyelectrolyte multilayer to modify the surface of titanium alloy and improve its antibacterial property. Scanning electron microscopy showed that AgNP with the size of 50 nm embedded in DAL/CHI multilayers homogeneously. X-ray photoelectron spectroscopy analysis indicated that the nanoparticles were silver (0) with peaks at 368.4 and 374.4 eV, respectively. The formation of silver (0) without the addition of reductants was due to the self-polymerization of dopamine, which can reduce the silver cation into neutral metal. The polyelectrolyte multilayer coating enhanced the wettability of titanium alloy and promoted the fibroblast proliferation significantly, which could be attributed to the excellent biocompatibility of DAL/CHI. Despite the slight fall of L929 cell activity after AgNP incorporation, AgNP-DAL/CHI multilayer inhibited the growth of both Escherichia coli and Staphylococcus aureus. The above results demonstrate that dopamine decoration is a simple and effective way to induce the in-situ formation of AgNP within polyelectrolyte multilayer. Furthermore, the AgNP-containing multilayer considerably enhances the antibacterial activity of titanium alloy. The fabrication of AgNP-DAL/CHI multilayer on the surface of titanium implant might have great potential in orthopedic use. - Highlights: • Polyelectrolyte multilayer was fabricated through layer-by-layer assembly. • AgNP was formed in-situ and embedded within polyelectrolyte multilayer. • Surface of titanium was modified by AgNP-DAL/CHI multilayer with a facile method. • AgNP-DAL/CHI multilayer enhanced antibacterial activity of titanium alloy.

  9. X-ray photoelectron spectroscopy and transmission electron microscopy analysis of silver-coated gold nanorods designed for bionanotechnology applications

    Science.gov (United States)

    Watanabe, Fumiya; Nima, Zeid A.; Honda, Takumi; Mitsuhara, Masatoshi; Nishida, Minoru; Biris, Alexandru S.

    2017-01-01

    Multicomponent nano-agents were designed and built via a core-shell approach to enhance their surface enhanced Raman scattering (SERS) signals. These nano-agents had 36 nm × 12 nm gold nanorod cores coated by 4 nm thick silver shell films and a subsequent thin bifunctional thiolated polyethylene glycol (HS-PEG-COOH) layer. Ambient time-lapsed SERS signal measurements of these functionalized nanorods taken over a two-week period indicated no signal degradation, suggesting that large portions of the silver shells remained in pure metallic form. The morphology of the nanorods was characterized by transmission electron microscopy (TEM) and ultra-high resolution scanning TEM. X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) were utilized to assess the oxidation states of the silver shells covered by HS-PEG-COOH. The binding energies of Ag 3d XPS spectra yielded very small chemical shifts with oxidation; however, the AES peak shapes gave meaningful information about the extent of oxidation undergone by the nano-agent. While the silver shells without HS-PEG-COOH coatings oxidized significantly, the silver shells with HS-PEG-COOH remained predominantly metallic. In fact, six month-old samples still retained mostly metallic silver shells. These findings further demonstrate the stability and longevity of the nanostructures, indicating their significant potential as plasmonically active agents for highly sensitive detection in various biological systems, including cancer cells, tissues, or even organisms.

  10. Citrate coated silver nanoparticles with modulatory effects on aflatoxin biosynthesis in Aspergillus parasiticus

    Science.gov (United States)

    Mitra, Chandrani

    The manufacture and usage of silver nanoparticles has drastically increased in recent years (Fabrega et al. 2011a). Hence, the levels of nanoparticles released into the environment through various routes have measurably increased and therefore are concern to the environment and to public health (Panyala, Pena-Mendez and Havel 2008). Previous studies have shown that silver nanoparticles are toxic to various organisms such as bacteria (Kim et al. 2007), fungi (Kim et al. 2008), aquatic plants (He, Dorantes-Aranda and Waite 2012a), arthropods (Khan et al. 2015), and mammalian cells (Asharani, Hande and Valiyaveettil 2009) etc. Most of the toxicity studies are carried out using higher concentrations or lethal doses of silver nanoparticles. However, there is no information available on how the fungal community reacts to the silver nanoparticles at nontoxic concentrations. In this study, we have investigated the effect of citrate coated silver nanoparticles (AgNp-cit) at a size of 20nm on Aspergillus parasiticus, a popular plant pathogen and well-studied model for secondary metabolism (natural product synthesis). A. parasiticus produces 4 major types of aflatoxins. Among other aflatoxins, aflatoxin B1 is considered to be one of most potent naturally occurring liver carcinogen, and is associated with an estimated 155,000 liver cancer cases globally (Liu and Wu 2010); therefore, contaminated food and feed are a significant risk factor for liver cancer in humans and animals (CAST 2003; Liu and Wu 2010). In this study, we have demonstrated the uptake of AgNp-cit (20nm) by A. parasiticus cells from the growth medium using a time course ICP-OES experiment. It was observed that the uptake of AgNp-cit had no effect on fungal growth and significantly decreased intracellular oxidative stress. It also down-regulated aflatoxin biosynthesis at the level of gene expression of aflatoxin pathway genes and the global regulatory genes of secondary metabolism. We also observed that the

  11. Fiber optic probes based on silver-only coated hollow glass waveguides for ionizing beam radiation dosimetry

    Science.gov (United States)

    Darafsheh, Arash; Liu, Haoyang; Melzer, Jeffrey E.; Taleei, Reza; Harrington, James A.; Kassaee, Alireza; Zhu, Timothy C.; Finlay, Jarod C.

    2016-03-01

    Čerenkov contamination is a significant issue in radiation detection by fiber-coupled scintillators. To enhance the scintillation signal transmission while minimizing Čerenkov contamination, we designed a fiber probe using a silver-only coated hollow waveguide (HWG). The HWG tip with inserted scintillator, embedded in tissue mimicking phantoms, was irradiated with clinical electron and photon beams. Optical spectra of irradiated tips were taken using a fiber spectrometer, and the signal was deconvolved with a linear fitting algorithm. The resultant decomposed spectra of the scintillator with and without Čerenkov correction were in good agreement with measurements performed by an electron diode and ion chamber for electron and photon beam dosimetry, respectively, indicating the minimal effect of Čerenkov contamination. Compared with a silver/dielectric coated HWG fiber dosimeter design we observed higher signal transmission in our design based on the use of silver-only HWG.

  12. MICRO-MATERIAL HANDLING, EMPLOYING E-BEAM COATINGS OF COPPER AND SILVER

    Directory of Open Access Journals (Sweden)

    S. Matope

    2012-01-01

    Full Text Available

    ENGLISH ABSTRACT: Van der Waals forces and other adhesive forces impose great challenges on micro-material handling. Mechanical grippers fail to release micro-parts reliably because of them. This paper explores how the problematic Van der Waals forces may be used for micro-material handling purposes using surface roughnesses generated by e-beam coatings of copper and silver on silicon. An atomic force microscope, model Asylum MFP 3 D-Bio with version 6.22A software, was used to measure the forces exerted by the surfaces. A silver coating of 1.41 nm rms surface roughness value is found to exert the highest Van der Waals force, followed by a copper coating of 2.72 nm rms; a copper coating of 217 nm rms exerts the least force. This implies that, in a reliable micro-material handling system, these coatings are suitable for the interactive surfaces of the placement position, micro-gripper, and the pick-up position respectively.

    AFRIKAANSE OPSOMMING: Van der Waalskragte en ander bindingskragte hou steeds groot uitdagings in vir mikromateriaalhantering. As gevolg van hierdie bindingskragte stel meganiese gryptoerusting nie die mikro-partikels vry nie. Hierdie artikel ondersoek hoe die Van der Waalskragte gebruik kan word vir die mikro-materiaalhanteringsproses deur die gebruik van oppervlakgrofheid gegenereer deur ’n e-straal-laagbedekking van koper en silwer op silikon. ’n Atoomkrag mikroskoop, model Asylum MFP 3 D-Bio met weergawe 6.22A programmatuur, is gebruik om die kragte deur die oppervlakke uitgeoefen te meet. Daar is gevind dat ’n silwer laagbedekking met ’n oppervlakgrofheid van 1.41nm wortel-gemiddelde-kwadraat (wgk die hoogste Van der Waalskrag uitoefen, gevolg deur ’n koper laagbedekking met ’n oppervlakgrofheid van 2.72nm wgk; ’n koper laagbedekking met ’n grofheid van 217nm wgk het die kleinste krag uitgeoefen. Dit impliseer dat, vir ’n betroubare mikro-materiaalhanteringsisteem, hierdie laagbedekkings geskik

  13. Hepatoprotective effect of engineered silver nanoparticles coated bioactive compounds against diethylnitrosamine induced hepatocarcinogenesis in experimental mice.

    Science.gov (United States)

    Prasannaraj, Govindaraj; Venkatachalam, Perumal

    2017-02-01

    animals group. Histopathological investigation reveals decreased fat accumulation, appearance of binucleated cells in nanoparticle treated animals and showed mere normal cells induced by DEN. Argyrophilic nucleolar organiser region (AgNORs) had a significant decrease in number of acidic proteins and mast cells assay showed decrease of metachromatic cells in nanoparticles treated animal groups over control. Present results strongly suggest that biomolecule coated silver nanoparticles exposure showed potential hepatoprotective effect against DEN induced liver cancer and could be used as an effective anticancer nanodrug.

  14. Antibacterial and bioactivity of silver substituted hydroxyapatite/TiO{sub 2} nanotube composite coatings on titanium

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Yajing [Institute of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu 610054 (China); Zhang, Xuejiao [Medical Informatics, Hebei North University, Zhangjiakou 075000 (China); Huang, Yong [Institute of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu 610054 (China); College of Lab Medicine, Hebei North University, Zhangjiakou 075000 (China); Ding, Qiongqiong [Institute of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu 610054 (China); Pang, Xiaofeng, E-mail: xfpang@aliyun.com [Institute of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu 610054 (China)

    2014-09-30

    Highlights: • Silver-substituted hydroxyapatite coating was successfully deposited on anodic TiO{sub 2} nanotubes by electrochemical deposition. • The bond strength between the AgHAp coatings and the substrate was improved by anodization pretreatment. • The antibacterial capability of the HAp coatings were enhanced with Ag{sup +} incorporation against E. coli. • The AgHAp coatings showed good biocompatibility and no adverse effect in cell culture tests. - Abstract: Hydroxyapatite doped with Ag{sup +} ions (AgHAp) was synthesized via electrochemical deposition method on anodized titanium. The samples were characterized via X-ray diffraction, Fourier transform infrared spectrum analysis, X-Ray photoelectron spectroscopy and scanning electron microscopy to investigate the phase formation and microstructure of the samples. Highly ordered TiO{sub 2} nanotubes with a diameter of 100 nm were successfully synthesized, and the AgHAp coating was deposited on the TiO{sub 2} nanotubes, which has a thickness of about 17.7 ± 1.5 μm. Moreover, silver was uniformly-distributed on the nanotubes. Bioactivity and electrochemical studies were performed for the AgHAp-coated TiO{sub 2} in a simulated body fluid, where significant good bioactivity and corrosion resistance were exhibited. The antibacterial and osteoblast cell adhesion tests in vitro revealed that the AgHAp coating with 2.03 wt% silver had significant antibacterial and osteogenic properties. Thus, the AgHAp coating was regarded as a promising candidate for coating orthopedic implants.

  15. Quantifying the influence of polymer coatings on the serum albumin corona formation around silver and gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Treuel, Lennart, E-mail: lennart.treuel@kit.edu [Karlsruhe Institute of Technology (KIT), Institute of Applied Physics and Center for Functional Nanostructures (CFN) (Germany); Malissek, Marcelina; Grass, Stefan [University of Duisburg-Essen, Institute for Physical Chemistry (Germany); Diendorf, Joerg; Mahl, Dirk; Meyer-Zaika, Wolfgang; Epple, Matthias [University of Duisburg-Essen, Institute of Inorganic Chemistry and Center for Nanointegration Duisburg-Essen (CeNIDE) (Germany)

    2012-09-15

    When nanoparticles (NPs) come into contact with biological fluids, proteins, and other biomolecules interact with their surface. Upon exposure to biological fluids a layer of proteins adsorbs onto their surface, the so-called protein corona, and interactions of biological systems with NPs are therefore mediated by this corona. Here, interactions of serum albumin with silver and gold NPs were quantitatively investigated using circular dichroism spectroscopy. Moreover, surface enhanced Raman spectroscopy was used for further elucidation of protein binding to silver surfaces. The decisive role of poly(vinylpyrrolidone), coatings on the protein adsorption was quantitatively described for the first time and the influential role of the polymer coatings is discussed. Research in nanotoxicology may benefit from such molecular scale data as well as scientific approaches seeking to improve nanomedical applications by using a wide range of polymer surface coatings to optimize biological transport and medical action of NPs.

  16. Multipactor suppression by micro-structured gold/silver coatings for space applications

    Energy Technology Data Exchange (ETDEWEB)

    Nistor, Valentin, E-mail: valentin.nistor@uam.es [Departamento de Fisica Aplicada, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); González, Luis A. [Departamento de Fisica Aplicada, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Aguilera, Lydya; Montero, Isabel [Instituto de Ciencia de Materiales de Madrid (CSIC), Cantoblanco, 28049 Madrid (Spain); Galán, Luis [Departamento de Fisica Aplicada, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Wochner, Ulrich [Tesat Spacecom GmbH and Co. KG,Gerberstr. 49, D-71522 Backnang (Germany); Raboso, David [European Space Agency (ESA), European Space Research and Technology Centre (ESTEC), 2200 AG Noordwijk (Netherlands)

    2014-10-01

    Highlights: • Total suppression of the multipactor effect was achieved for a specific configuration of a high RF power K{sub u}-band waveguide. • Secondary emission of electrons was decreased by surfaces of high aspect ratio. • Simple techniques were used in the manufacturing of metallic microscopical rough coatings. • Surface analysis of the treatment was performed. • The RF insertion losses were improved with respect to Alodine, the standard coating for space applications. - Abstract: The secondary electron emission (SEE) from materials used in high power RF devices in space is the main trigger and sustaining mechanism of the resonant avalanche electron discharge known as the multipactor effect. It limits the attainable power of those devices. During recent decades, some scientific research has been focused on material properties for obtaining anti-multipactor coatings of low secondary emission yield (SEY). The European Space Agency (ESA) is leading a technological research on a new approach based on surface roughness that might perform as a kind of blackbody or Faraday cage effect. A multilayer coating structure was adopted for fulfilling the stringent requirements of the space. The surface of a standard silver plating was modified by a two-step treatment. First, a wet chemically etching process created a roughness of high aspect ratio, in the scale of microns. Secondly, the surface was coated with a protective 2 μm overlayer of gold, using magnetron sputtering. This anti-multipactor coating has been tested on several types of K{sub u}-band WR75 waveguide transformers and band-pass filters, with excellent results. The multipactor effect was suppressed for two waveguides, even when applying the maximum available power levels. As for the other final four, the increase of multipactor power level was in the range of 4–6 dB. These results were obtained after more than one year of air exposure. In spite of the strong roughness, the insertion losses were

  17. Colorimetric detection of trace copper ions based on catalytic leaching of silver-coated gold nanoparticles.

    Science.gov (United States)

    Lou, Tingting; Chen, Lingxin; Chen, Zhaopeng; Wang, Yunqing; Chen, Ling; Li, Jinhua

    2011-11-01

    A colorimetric, label-free, and nonaggregation-based silver coated gold nanoparticles (Ag/Au NPs) probe has been developed for detection of trace Cu(2+) in aqueous solution, based on the fact that Cu(2+) can accelerate the leaching rate of Ag/Au NPs by thiosulfate (S(2)O(3)(2-)). The leaching of Ag/Au NPs would lead to dramatic decrease in the surface plasmon resonance (SPR) absorption as the size of Ag/Au NPs decreased. This colorimetric strategy based on size-dependence of nanoparticles during their leaching process provided a highly sensitive (1.0 nM) and selective detection toward Cu(2+), with a wide linear detection range (5-800 nM) over nearly 3 orders of magnitude. The cost-effective probe allows rapid and sensitive detection of trace Cu(2+) ions in water samples, indicating its potential applicability for the determination of copper in real samples.

  18. Examination of Ostwald ripening in the photocatalytic growth of silver nanoparticles on titanium dioxide coatings

    Science.gov (United States)

    Piwoński, Ireneusz; Spilarewicz-Stanek, Kaja; Kisielewska, Aneta; Kądzioła, Kinga; Cichomski, Michał; Ginter, Joanna

    2016-06-01

    Silver nanoparticles (AgNPs) were grown on the surface of titanium dioxide coating (TiO2) using a photochemical method. The size and number of AgNPs were monitored using scanning electron microscopy (SEM) after 20, 30, 180 and 300 s of UV illumination. It was found that for short illumination times (20 s) a significant number of small nanoparticles were grown. However, after an additional 10 s of illumination, small nanoparticles were subject to decomposition and the released Ag+ ions were utilized for the growth of the existing larger nanoparticles, causing an increase in their dimensions. The observed results indicate that the nucleation and further growth of AgNPs proceed according to Ostwald ripening. For longer illumination times (180, 300 s) a coalescence of closely located particles was observed.

  19. Immunomodulatory effect of gelatin-coated silver nanoparticles in mice: Ultrastructural evaluation.

    Science.gov (United States)

    Ahmed, Omar Bauomy; Mahmoud, Usama Taha; Elganady, Sara; Nafady, Allam Mohamed; Afifi, Salah Mohamed Hassan

    2016-01-01

    Silver nanoparticles (SNP) are used in many pharmaceutical, cosmetic, and industrial products already available in the market. Although they are considered relatively safe, many toxic and pathological alterations in different organs including immune organs were reported after SNP administration. In this study, 10-week-old male mice (n = 20) were divided into two groups. Ten mice received greenly synthesized gelatin-coated silver nanoparticles in a dose of 10 mg/kg body weight for five consecutive days while the other 10 received 0.5 ml of distilled water daily for 5 days and kept as control. At the sixth day, all mice were sacrificed; blood and tissue samples were collected and prepared for pathological analysis. Liver and kidney lesions were in the form of degenerative and inflammatory changes. Interestingly, the immune organs were drastically affected by SNP treatment. Severe hyperplasia of the Peyer's patches was noticed in the intestines of intoxicated animals both in gross and microscopic examination. Spleen was enlarged and showed large number of megakaryocytes. The particles were encountered in membrane-bound phagosomes inside macrophages in different organs like lungs and spleen. Blood picture complied to morphological findings with an increase in monocytes and eosinophils accompanied by drop in the platelets count in the intoxicated animals.

  20. Synthesis Optimisation of Lysozyme Monolayer-Coated Silver Nanoparticles in Aqueous Solution

    Directory of Open Access Journals (Sweden)

    A. V. Yakovlev

    2014-01-01

    Full Text Available This paper presents an optimisation of the synthesis of silver nanoparticles encapsulated in a biological shell. The synthesis was carried out in an aqueous solution of silver nitrate. Sodium borohydride was used as a reducing agent. Lysozyme served as a bioactive coating agent. The samples produced were studied using dynamic light scattering, transmission electron microscopy, and UV-Vis spectroscopy. The function of the dependence of the reagent ratio in obtained sols on optical properties is shown. Furthermore, the influence of the synthesis temperature, reactant ratio, and order of mixing on the particle size distribution parameters is shown. The optimal reagent mass ratio, NaBH4 : LYZ : AgNO3 = 0.22 : 0.77 : 1, is established. The resulting composition allows the synthesis of particles with a mean diameter of 18 nm and a bioshell thickness of ≈3.5 nm. Moreover, the necessity of the synthesis optimisation and precise parameter control is clearly demonstrated.

  1. Biobased silver nanocolloid coating on silk fibers for prevention of post-surgical wound infections.

    Science.gov (United States)

    Dhas, Sindhu Priya; Anbarasan, Suruthi; Mukherjee, Amitava; Chandrasekaran, Natarajan

    2015-01-01

    Bombyx mori silk fibers are an important biomaterial and are used in surgical sutures due to their remarkable biocompatibility. The major drawback to the application of biomaterials is the risk of bacterial invasion, leading to clinical complications. We have developed an easy and cost-effective method for fabrication of antibacterial silk fibers loaded with silver nanoparticles (AgNPs) by an in situ and ex situ process using an aqueous extract of Rhizophora apiculata leaf. Scanning electron microscopy revealed that well dispersed nanoparticles impregnated the silk fibers both in situ and ex situ. The crystalline nature of the AgNPs in the silk fibers was demonstrated by X-ray diffraction. The thermal and mechanical properties of the silk fibers were enhanced after they were impregnated with AgNPs. The silver-coated silk fibers fabricated by the in situ and ex situ method exhibited more than 90% inhibition against Pseudomonas aeruginosa and Staphylococcus aureus. Silk fibers doped with AgNPs were found to be biocompatible with 3T3 fibroblasts. The results obtained represent an important advance towards the clinical application of biocompatible AgNP-loaded silk fibers for prevention of surgical wound infections.

  2. Polyacrylonitrile nanofibers coated with silver nanoparticles using a modified coaxial electrospinning process

    Directory of Open Access Journals (Sweden)

    Yu DG

    2012-11-01

    Full Text Available Deng-Guang Yu,1 Jie Zhou,2 Nicholas P Chatterton,3 Ying Li,1 Jing Huang,2 Xia Wang11School of Materials Science and Engineering, University of Shanghai for Science and Technology, Shanghai, People's Republic of China; 2School of Life Sciences, East China Normal University, Shanghai, People's Republic of China; 3Faculty of Life Sciences, London Metropolitan University, London, United KingdomBackground: The objective of this investigation was to develop a new class of antibacterial material in the form of nanofibers coated with silver nanoparticles (AgNPs using a modified coaxial electrospinning approach. Through manipulation of the distribution on the surface of nanofibers, the antibacterial effect of Ag can be improved substantially.Methods: Using polyacrylonitrile (PAN as the filament-forming polymer matrix, an electrospinnable PAN solution was prepared as the core fluid. A silver nitrate (AgNO3 solution was exploited as sheath fluid to carry out the modified coaxial electrospinning process under varied sheath-to-core flow rate ratios.Results: Scanning electron microscopy and transmission electron microscopy demonstrated that the sheath AgNO3 solution can take a role in reducing the nanofibers' diameters significantly, a sheath-to-core flow rate ratio of 0.1 and 0.2 resulting in PAN nanofibers with diameters of 380 ± 110 nm and 230 ± 70 nm respectively. AgNPs are well distributed on the surface of PAN nanofibers. The antibacterial experiments demonstrated that these nanofibers show strong antimicrobial activities against Bacillus subtilis Wb800, and Escherichia coli dh5α.Conclusion: Coaxial electrospinning with AgNO3 solution as sheath fluid not only facilitates the electrospinning process, providing nanofibers with reduced diameters, but also allows functionalization of the nanofibers through coating with functional ingredients, effectively ensuring that the active antibacterial component is on the surface of the material, which leads to

  3. Polyelectrolyte Multilayer Film Coated Silver Nanorods: An Effective Carrier System for Externally Activated Drug Delivery

    Science.gov (United States)

    Paramasivam, Gokul; Sharma, Varsha; Sundaramurthy, Anandhakumar

    2017-08-01

    Nanoparticle anisotropy offers unique functions and features in comparison with spherical nanoparticles (NPs) and makes anisotropic nanoparticles (ANPs) promising candidates in applications like drug delivery, imaging, biosensing and theranostics. Presence of surface active groups (e.g. amine, and carboxylate groups) on their surface provides binding sites for ligands or other biomolecules, and hence, this could be targeted for specific part or cells in our body. In the quest of such surface modification, functionalization of ANPs along Layer-by-Layer (LbL) coating of oppositely charged polyelectrolytes (PE) reduces cellular toxicity and promotes easy encapsulation of drugs. In this work, we report the silver nanorods (AgNRs) synthesis by adsorbate directed synthetic approach using cetyltrimethyl ammonium bromide (CTAB). The formed ANPs is investigated by scanning electron microscopy (SEM) and UV-Visible (UV-Vis) spectroscopy revealing the shaping of AgNRs of 3-16 nm aspect ratio with some presence of triangles. These NRs were further coated with bio polymers of chitosan (CH) and dextran sulphate (DS) through LbL approach and used for encapsulation of water soluble anti-bacterial drugs like ciprofloxacin hydrochloride (CFH). The encapsulation of drugs and profiles of drug release were investigated and compared to that of spherical silver nanoparticles (AgNPs). The added advantages of the proposed drug delivery system (DDS) can be externally activated to release the loaded drug and used as contrast agents for biological imaging under exposure to NIR light. Such system shows unique and attractive characteristics required for drug delivery and bioimaging thus offering the scope for further development as theranostic material.

  4. Sorption of untreated and humic acid coated silver nanoparticles to environmental and model surfaces

    Science.gov (United States)

    Abraham, Priya M.; Baumann, Thomas; Schaumann, Gabriele E.

    2014-05-01

    The environmental fate of engineered nanoparticles is controlled their colloidal stability and their interaction with different environmental surfaces. Little is known about sorption of nanoparticles to environmental surfaces under quasi-equilibrium conditions. Nevertheless, sorption isotherms may also be a valuable means of studying nanoparticle-sorbent interactions. We investigated sorption of engineered silver nanoparticles (nAg) from stable and unstable suspensions in presence and absence of natural organic matter (NOM) to model surfaces (sorbents with specific chemical functional groups) and environmental materials (plant leaves and sand). Morphology and nanomechanical parameters of the surfaces covered with nanoparticles were assessed using atomic force microscopy (AFM) and scanning electron microscopy (SEM). The sorption of nAg from stable suspensions and in absence of NOM was non-linear and best described by a Langmuir model, where Langmuir coefficients varied with sorbent surface chemistry, which suggests monolayer sorption (Abraham et al. 2013). For nAg sorption from an unstable suspension, the sorption isotherms did not follow any classical sorption models, suggesting interplay between aggregation and sorption (Abraham et al. 2013). In contrast, sorption was strongly suppressed and exhibited linear sorption isotherms in the presence of NOM. The difference in sorption isotherms suggests predominance of different sorption mechanisms depending on presence or absence of NOM, which can be only partly explained by the NOM coating alone. On the basis of the current results, a partial release of NOM coating for sorption of certain surfaces cannot be excluded. The validity of the Langmuir isotherm suggests monolayer sorption, which can be explained by the blocking effect due to electrostatic repulsion of individual nanoparticles. In unstable suspensions, aggregates are instead formed in suspension, formed on the surface and then sorbed, or formed in both ways

  5. Disentangling the effects of polymer coatings on silver nanoparticle agglomeration, dissolution, and toxicity to determine mechanisms of nanotoxicity

    Energy Technology Data Exchange (ETDEWEB)

    Zook, Justin M., E-mail: jzook@nist.gov; Halter, Melissa D.; Cleveland, Danielle; Long, Stephen E. [National Institute of Standards and Technology, Material Measurement Laboratory (United States)

    2012-10-15

    Silver nanoparticles (AgNPs) are frequently coated with a variety of polymers, which may affect various interdependent mechanisms of toxicity or antimicrobial action, including agglomeration and dissolution rates. Here, we systematically measure how citrate, dextran, 5 and 20 kDa poly(ethylene glycol) (PEG), and poly(vinyl pyrrolidone) coatings affect AgNP agglomeration, dissolution, and toxicity. In addition, to disentangle the coatings' effects on agglomeration from their other effects, we produce multiple stable agglomerate sizes of several of the coated {approx}23 nm AgNPs ranging from singly-dispersed to mean agglomerate sizes of several hundred nanometers. These dispersions allow us to independently study the effects of agglomeration and polymer coating on dissolution rate and hemolytic toxicity. We find that both hemolytic toxicity and dissolution rate are highest for the 5 kDa PEG coating, and toxicity and dissolution rate decrease significantly with increasing agglomerate size independent of coating. This correlation between toxicity and dissolution rate suggests that both polymer coating and agglomeration may affect hemolytic toxicity largely through their effects on dissolution. Because both the AgNP dissolution rate and hemolysis decrease only moderately compared to the large increases in agglomerate size, AgNPs' hemolytic toxicity may be caused by their large surface area and consequently high dissolution rate, rather than from other size-specific effects. At the silver concentrations used in this work, silver dissolved from AgNPs is expected to be primarily in the form of AgCl NPs, which are therefore more likely than Ag{sup +} ions to be the primary drivers of hemolytic toxicity. In addition, all AgNPs we tested are much more toxic to horse red blood cells than sheep red blood cells, highlighting the complexity of toxic responses and the need to test toxicity in multiple biological systems.

  6. Electrocatalytic response of poly(cobalt tetraaminophthalocyanine)/multi-walled carbon nanotubes-Nafion modified electrode toward sulfadiazine in urine

    Institute of Scientific and Technical Information of China (English)

    Xiao-ping HONG; Yah ZHU; Yan-zhen ZHANG

    2012-01-01

    A highly sensitive amperometric sulfadiazine sensor fabricated by electrochemical deposition of poly(cobalt tetraaminophthalocyanine) (poly(CoⅡTAPc)) on the surface of a multi-walled carbon nanotubes-Nafion (MWCNTs-Nafion) modified electrode is described.This electrode showed a very attractive performance by combining the advantages of Co11TAPc,MWCNTs,and Nafion.Compared with the bare glassy carbon electrode (GCE) and the MWCNTs-Nafion modified electrode,the electrocatalytic activity of poly(CoⅡTAPc)-coated MWCNTs-Nafion GCE generated greatly improved electrochemical detections toward sulfadiazine including low oxidation potential,high current responses,and good anti-fouling performance.The oxidation peak currents of sulfadiazine obtained on the new modified electrode increased linearly while increasing the concentration of sulfadiazine from 0.5 to 43.5 μmol/L with the detection limit of 0.17 μmol/L.

  7. In Vitro Antifungal Activity against Oral Candida Species Using a Denture Base Coated with Silver Nanoparticles

    Directory of Open Access Journals (Sweden)

    Yoshiaki Kamikawa

    2014-01-01

    Full Text Available Although oral Candida easily adheres to denture base materials, many denture detergents are effective only against bacteria but not against Candida. Silver nanoparticles (AgNPs, which are known to have potent antibacterial and antifungal activity, have been used in the prevention of oral candidiasis (OC. We evaluated the adherence of Candida albicans and Candida glabrata on a heat-cured Acron resin piece supported by AgNPs by low-vacuum scanning electron microscopy (SEM and measuring colony-forming units. C. albicans and C. glabrata increasingly adhered to the resin surface of the control piece over time, but the adhesion AgNP of both Candida species to the AgNP-coated surface was significantly inhibited (P<0.001. Low-vacuum SEM revealed that C. albicans and C. glabrata on the resin surface of control pieces appeared as oval colonies, with a major axis of 3-4 μm and a smooth cell wall, but those on the AgNP-coated resin surface were less abundant than the control and showed swollen yeast features, with a major axis of more than 5 μm and a corrugated cell wall. Our results suggest a way to prevent denture-associated OC by using denture base materials processed by AgNPs.

  8. Single-step electrochemical deposition of antimicrobial orthopaedic coatings based on a bioactive glass/chitosan/nano-silver composite system.

    Science.gov (United States)

    Pishbin, F; Mouriño, V; Gilchrist, J B; McComb, D W; Kreppel, S; Salih, V; Ryan, M P; Boccaccini, A R

    2013-07-01

    Composite orthopaedic coatings with antibacterial capability containing chitosan, Bioglass® particles (9.8μm) and silver nanoparticles (Ag-np) were fabricated using a single-step electrophoretic deposition (EPD) technique, and their structural and preliminary in vitro bactericidal and cellular properties were investigated. Stainless steel 316 was used as a standard metallic orthopaedic substrate. The coatings were compared with EPD coatings of chitosan and chitosan/Bioglass®. The ability of chitosan as both a complexing and stabilizing agent was utilized to form uniformly deposited Ag-np. Due to the presence of Bioglass® particles, the coatings were bioactive in terms of forming carbonated hydroxyapatite in simulated body fluid (SBF). Less than 7wt.% of the incorporated silver was released over the course of 28days in SBF and the possibility of manipulating the release rate by varying the deposition order of coating layers was shown. The low released concentration of Ag ions (effects. This was attributed to the relatively high concentration of Ag-np incorporated in the coatings.

  9. Adsorption and sub-nanomolar sensing of thioflavin T on colloidal gold nanoparticles, silver nanoparticles and silver-coated films studied using surface-enhanced Raman scattering.

    Science.gov (United States)

    Maiti, Nandita; Chadha, Ridhima; Das, Abhishek; Kapoor, Sudhir

    2015-01-01

    Raman and surface-enhanced Raman scattering (SERS) studies of thioflavin T (ThT) in solid, solution, gold nanoparticles (GNPs), silver nanoparticles (SNPs) and silver-coated films (SCFs) were investigated. Concentration-dependent SERS spectrum of ThT in GNPs and SNPs indicated the existence of two possible structures, one with the torsional angle (φ) between benzothiazole and dimethylaminobenzene rings being 37° and the other with φ=90°. The SERS spectrum of ThT in SCFs were similar to the Raman spectrum of solid and solution that suggests φ=37°. In this paper, the high sensitivity of the SERS technique was employed for sub-nanomolar (picomolar) sensing of ThT.

  10. Nanostructured titanium–silver coatings with good antibacterial activity and cytocompatibility fabricated by one-step magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Bai, Long [Research Institute of Surface Engineering, Taiyuan University of Technology, Taiyuan (China); Hang, Ruiqiang, E-mail: hangruiqiang@tyut.edu.cn [Research Institute of Surface Engineering, Taiyuan University of Technology, Taiyuan (China); Gao, Ang [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Zhang, Xiangyu; Huang, Xiaobo; Wang, Yueyue; Tang, Bin [Research Institute of Surface Engineering, Taiyuan University of Technology, Taiyuan (China); Zhao, Lingzhou, E-mail: zhaolingzhou1983@hotmail.com [State Key Laboratory of Military Stomatology, Department of Periodontology, School of Stomatology, The Fourth Military Medical University, Xi’an (China); Chu, Paul K. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)

    2015-11-15

    Graphical abstract: - Highlights: • We fabricate Ti–Ag coatings with different Ag contents and surface morphologies. • The Ti–Ag coatings possess long-term antibacterial ability. • Increased Ag contents in the coatings leads to enhanced osteoblast functions. - Abstract: Bacterial infection and loosing are serious complications for biomedical implants in the orthopedic, dental, and other biomedical fields and the ideal implants should combine good antibacterial ability and bioactivity. In this study, nanostructured titanium–silver (Ti–Ag) coatings with different Ag contents (1.2 to 21.6 at%) are prepared on Ti substrates by magnetron sputtering. As the Ag concentration is increased, the coatings change from having dense columnar crystals to sparse ones and eventually no columnar structure. The Ti–Ag coatings can effectively kill Staphylococcus aureus during the first few days and remain moderately antibacterial after immersion for 75 days. Compared to pure Ti, the Ti–Ag coatings show good cytocompatibility as indicated by good osteoblast adhesion, proliferation, intracellular total protein synthesis, and alkaline phosphatase (ALP) activity. In addition, cell spreading, collagen secretion, and extracellular matrix mineralization are promoted on the coatings with the proper Ag contents due to the nanostructured morphological features. Our results indicate that favorable antibacterial activity and osseointegration ability can be simultaneously achieved by regulating the Ag contents in Ti–Ag coatings.

  11. Silver nanoparticles and growth factors incorporated hydroxyapatite coatings on metallic implant surfaces for enhancement of osteoinductivity and antibacterial properties.

    Science.gov (United States)

    Xie, Chao-Ming; Lu, Xiong; Wang, Ke-Feng; Meng, Fan-Zhi; Jiang, Ou; Zhang, Hong-Ping; Zhi, Wei; Fang, Li-Ming

    2014-06-11

    Research on incorporation of both growth factors and silver (Ag) into hydroxyapatite (HA) coatings on metallic implant surfaces for enhancing osteoinductivity and antibacterial properties is a challenging work. Generally, Ag nanoparticles are easy to agglomerate and lead to a large increase in local Ag concentration, which could potentially affect cell activity. On the other hand, growth factors immobilization requires mild processing conditions so as to maintain their activities. In this study, bone morphology protein-2 (BMP-2) and Ag nanoparticle contained HA coatings were prepared on Ti surfaces by combining electrochemical deposition (ED) of Ag and electrostatic immobilization of BMP-2. During the ED process, chitosan (CS) was selected as the stabilizing agent to chelate Ag ions and generate Ag nanoparticles that are uniformly distributed in the coatings. CS also reduces Ag toxicity while retaining its antibacterial activity. Afterwards, a BMP/heparin solution was absorbed on the CS/Ag/HA coatings. Consequently, BMP-2 was immobilized on the coatings by the electrostatic attraction between CS, heparin, and BMP-2. Sustained release of BMP-2 and Ag ions from HA coatings was successfully demonstrated for a long period. Results of antibacterial tests indicate that the CS/Ag/HA coatings have high antibacterial properties against both Staphylococcus epidermidis and Escherichia coli. Osteoblasts (OB) culture reveals that the CS/Ag/HA coatings exhibit good biocompatibility. Bone marrow stromal cells (BMSCs) culture indicates that the BMP/CS/Ag/HA coatings have good osteoinductivity and promote the differentiation of BMSCs. Ti bars with BMP/CS/Ag/HA coatings were implanted into the femur of rabbits to evaluate the osteoinductivity of the coatings. Results indicate that BMP/CS/Ag/HA coatings favor bone formation in vivo. In summary, this study presents a convenient and effective method for the incorporation of growth factors and antibacterial agents into HA coatings. This

  12. Synthesis, characterization and antibacterial activity against Gram positive and Gram negative bacteria of biomimetically coated silver nanoparticles.

    Science.gov (United States)

    Amato, Elvio; Diaz-Fernandez, Yuri A; Taglietti, Angelo; Pallavicini, Piersandro; Pasotti, Luca; Cucca, Lucia; Milanese, Chiara; Grisoli, Pietro; Dacarro, Cesare; Fernandez-Hechavarria, Jose M; Necchi, Vittorio

    2011-08-02

    In the present work, we describe a simple procedure to produce biomimetically coated silver nanoparticles (Ag NPs), based on the postfunctionalization and purification of colloidal silver stabilized by citrate. Two biological capping agents have been used (cysteine Cys and glutathione GSH). The composition of the capped colloids has been ascertained by different techniques and antibacterial tests on GSH-capped Ag NPs have been conducted under physiological conditions, obtaining values of Minimum Inhibitory Concentration (MIC) of 180 and 15 μg/mL for Staphylococcus aureus and Escherichia coli, respectively. The antibacterial activity of these GSH capped NPs can be ascribed to the direct action of metallic silver NPs, rather than to the bulk release of Ag(+).

  13. Transformations of citrate and Tween coated silver nanoparticles reacted with Na{sub 2}S

    Energy Technology Data Exchange (ETDEWEB)

    Baalousha, M. [Center for Environmental Nanoscience and Risk, Department of Environmental Health Sciences, Arnold School of Public Health, University of South Carolina, Columbia, SC 29028 (United States); Arkill, K.P. [School of Biochemistry, University of Bristol, Bristol BS8 1TD (United Kingdom); Romer, I. [School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham B15 2TT (United Kingdom); Palmer, R.E. [School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT (United Kingdom); Lead, J.R. [Center for Environmental Nanoscience and Risk, Department of Environmental Health Sciences, Arnold School of Public Health, University of South Carolina, Columbia, SC 29028 (United States); School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham B15 2TT (United Kingdom)

    2015-01-01

    Silver nanoparticles (Ag NPs) are susceptible to transformations in environmental and biological media such as aggregation, oxidation, dissolution, chlorination, sulfidation, formation/replacement of surface coatings following interaction with natural organic matter (NOM). This paper investigates the impact of surface coating and Suwannee River fulvic acid (SRFA) on the transformations and behavior of Ag NPs (citrate coated and Tween coated; cit-Ag NPs and Tween-Ag NPs, respectively), following reaction with different concentrations of Na{sub 2}S solution (as a source of sulfide species, H{sub 2}S and HS{sup −}). These transformations and the dominant mechanisms of transformations were investigated using UV–vis and scanning transmission electron microscopy coupled with electron energy loss spectroscopy. Here, we have shown that Ag NP surface coating impacts their dissolution following dilution in ultrahigh purity water, with higher extent of dissolution of Tween-Ag NPs compared with cit-Ag NPs. Tween-Ag NPs are susceptible to dissolution following their sulfidation at low S/Ag molar ratio. Suwannee River fulvic acid (SRFA) slows down the dissolution of Tween-Ag NPs at low sulfide concentrations and reduces the aggregation of cit-Ag NP in the presence of sodium sulfide. Sulfidation appears to occur by direct interaction of sulfide species with Ag NPs rather than by indirect reaction of sulfide with dissolved Ag species subsequent to dissolution. Furthermore, the sulfidation process results in the formation of partially sulfidized Ag NPs containing unreacted (metallic) subgrains at the edge of the NPs for Tween-Ag NPs in the presence of high sulfide concentration (2000 nM Na{sub 2}S), which occurred to less extent at lower Na{sub 2}S concentration for Tween-Ag NPs and at all concentrations of Na{sub 2}S for cit-Ag NPs. Thus, sulfidized Ag NPs may preserve some of the properties of the Ag NPs such as their potential to shed Ag{sup +} ions and their toxic potential

  14. Hybrid biocomposite with a tunable antibacterial activity and bioactivity based on RF magnetron sputter deposited coating and silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ivanova, A.A. [Department of Theoretical and Experimental Physics, Center of Technology, National Research Tomsk Polytechnic University, 634050 Tomsk (Russian Federation); Surmenev, R.A., E-mail: rsurmenev@gmail.com [Department of Theoretical and Experimental Physics, Center of Technology, National Research Tomsk Polytechnic University, 634050 Tomsk (Russian Federation); Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB, 70569 Stuttgart (Germany); Surmeneva, M.A.; Mukhametkaliyev, T. [Department of Theoretical and Experimental Physics, Center of Technology, National Research Tomsk Polytechnic University, 634050 Tomsk (Russian Federation); Loza, K.; Prymak, O.; Epple, M. [Inorganic Chemistry and Center for Nanointegration Duisburg-Essen (CeNIDE), University of Duisburg-Essen, 45117 Essen (Germany)

    2015-02-28

    Highlights: • A biocomposite of hydroxyapatite film and silver nanoparticles (AgNPs) was tested. • The concentration of the released silver in phosphate or acetate buffer was studied. • The concentration and release rate of AgNPs can be controlled in a tailored manner. - Abstract: In this work, we describe fabrication techniques used to prepare a multifunctional biocomposite based on a hydroxyapatite (HA) coating and silver nanoparticles (AgNPs). AgNPs synthesized by a wet chemical reduction method were deposited on Ti substrates using a dripping/drying method followed by deposition of calcium phosphate (CaP) coating via radio-frequency (RF) magnetron sputter-deposition. The negatively charged silver nanoparticles (zeta potential −21 mV) have a spherical shape with a metallic core diameter of 50 ± 20 nm. The HA coating was deposited as a dense nanocrystalline film over a surface of AgNPs. The RF-magnetron sputter deposition of HA films on the AgNPs layer did not affect the initial content of AgNPs on the substrate surface as well as NPs size and shape. SEM cross-sectional images taken using the backscattering mode revealed a homogeneous layer of AgNPs under the CaP layer. The diffraction patterns from the coatings revealed reflexes of crystalline HA and silver. The concentration of Ag ions released from the biocomposites after 7 days of immersion in phosphate and acetate buffers was estimated. The obtained results revealed that the amount of silver in the solutions was 0.27 ± 0.02 μg mL{sup −1} and 0.54 ± 0.02 μg mL{sup −1} for the phosphate and acetate buffers, respectively, which corresponded well with the minimum inhibitory concentration range known for silver ions in literature. Thus, this work establishes a new route to prepare a biocompatible layer using embedded AgNPs to achieve a local antibacterial effect.

  15. Ageing of plasma-mediated coatings with embedded silver nanoparticles on stainless steel: An XPS and ToF-SIMS investigation

    Science.gov (United States)

    Zanna, S.; Saulou, C.; Mercier-Bonin, M.; Despax, B.; Raynaud, P.; Seyeux, A.; Marcus, P.

    2010-09-01

    Nanocomposite thin films (˜170 nm), composed of silver nanoparticles enclosed in an organosilicon matrix, were deposited onto stainless steel, with the aim of preventing biofilm formation. The film deposition was carried out under cold plasma conditions, combining radiofrequency (RF) glow discharge fed with argon and hexamethyldisiloxane and simultaneous silver sputtering. XPS and ToF-SIMS were used to characterize Ag-organosilicon films in native form and after ageing in saline solution (NaCl 0.15 M), in order to further correlate their lifetime with their anti-fouling properties. Two coatings with significantly different silver contents (7.5% and 20.3%) were tested. Surface analysis confirmed the presence of metallic silver in the pristine coating and revealed significant modifications after immersion in the saline solution. Two different ageing mechanisms were observed, depending on the initial silver concentration in the film. For the sample exhibiting the low silver content (7.5%), the metal amount decreased at the surface in contact with the solution, due to the release of silver from the coating. As a result, after a 2-day exposure, silver nanoparticles located at the extreme surface were entirely released, whereas silver is still present in the inner part of the film. The coating thickness was not modified during ageing. In contrast, for the high silver content film (20.3%), the thickness decreased with immersion time, due to significant silver release and matrix erosion, assigned to a percolation-like effect. However, after 18 days of immersion, the delamination process stopped and a thin strongly bounded layer remained on the stainless steel surface.

  16. The effect of the deposition parameters on size, distribution and antimicrobial properties of photoinduced silver nanoparticles on titania coatings

    Science.gov (United States)

    Piwoński, Ireneusz; Kądzioła, Kinga; Kisielewska, Aneta; Soliwoda, Katarzyna; Wolszczak, Marian; Lisowska, Katarzyna; Wrońska, Natalia; Felczak, Aleksandra

    2011-06-01

    Controlled photodeposition of silver nanoparticles (AgNP) on titania coatings using two different sources of UV light is described. Titania (anatase) thin films were prepared by the sol-gel dip-coating method on silicon wafers. AgNPs were grown on the titania surface as a result of UV illumination of titania films immersed in aqueous solutions of silver nitrate. UV xenon lamp or excimer laser, both operating at the wavelength 351 ± 5 nm, was used as illumination sources. The AFM topography of AgNP/TiO 2 nanocomposites revealed that silver nanoparticles could be synthesized by both sources of illumination, however the photocatalysis carried out by UV light from xenon lamp illumination leads to larger AgNP than those synthesized using the laser beam. It was found that the increasing concentration of silver ions in the initial solution increases the number of Ag nanoparticles on the titania surface, while longer time of irradiation results the growth of larger size nanoparticles. Antibacterial tests performed on TiO 2 covered by Ag nanoparticles revealed that increasing density of nanoparticles enhances the inhibition of bacterial growth. It was also found that antibacterial activity drops by only 10-15% after 6 cycles compared to the initial use.

  17. The effect of the deposition parameters on size, distribution and antimicrobial properties of photoinduced silver nanoparticles on titania coatings

    Energy Technology Data Exchange (ETDEWEB)

    Piwonski, Ireneusz, E-mail: irek@uni.lodz.pl [University of Lodz, Department of Technology and Chemistry of Materials, Pomorska 163, 90-236 Lodz (Poland); Kadziola, Kinga; Kisielewska, Aneta; Soliwoda, Katarzyna [University of Lodz, Department of Technology and Chemistry of Materials, Pomorska 163, 90-236 Lodz (Poland); Wolszczak, Marian [Technical University of Lodz, Institute of Applied Radiation Chemistry, Wroblewskiego 15, 93-590 Lodz (Poland); Lisowska, Katarzyna; Wronska, Natalia; Felczak, Aleksandra [University of Lodz, Department of Industrial Microbiology and Biotechnology, Pilarskiego 14/16, 90-231 Lodz (Poland)

    2011-06-01

    Controlled photodeposition of silver nanoparticles (AgNP) on titania coatings using two different sources of UV light is described. Titania (anatase) thin films were prepared by the sol-gel dip-coating method on silicon wafers. AgNPs were grown on the titania surface as a result of UV illumination of titania films immersed in aqueous solutions of silver nitrate. UV xenon lamp or excimer laser, both operating at the wavelength 351 {+-} 5 nm, was used as illumination sources. The AFM topography of AgNP/TiO{sub 2} nanocomposites revealed that silver nanoparticles could be synthesized by both sources of illumination, however the photocatalysis carried out by UV light from xenon lamp illumination leads to larger AgNP than those synthesized using the laser beam. It was found that the increasing concentration of silver ions in the initial solution increases the number of Ag nanoparticles on the titania surface, while longer time of irradiation results the growth of larger size nanoparticles. Antibacterial tests performed on TiO{sub 2} covered by Ag nanoparticles revealed that increasing density of nanoparticles enhances the inhibition of bacterial growth. It was also found that antibacterial activity drops by only 10-15% after 6 cycles compared to the initial use.

  18. Developmental and reproductive toxicity of PVP/PEI-coated silver nanoparticles to zebrafish.

    Science.gov (United States)

    Orbea, Amaia; González-Soto, Nagore; Lacave, José María; Barrio, Irantzu; Cajaraville, Miren P

    2017-09-01

    Cellular and molecular mechanisms of toxicity of silver nanoparticles (NPs) and their toxicity to fish embryos after waterborne exposure have been widely investigated, but much less information is available regarding the effect of Ag NPs on physiological functions such as growth or reproduction. In this work, the effects of waterborne exposure of adult zebrafish (Danio rerio) to PVP/PEI coated Ag NPs (~5nm) on reproduction (fecundity) were investigated. Moreover, the development of the embryos after parental exposure was compared with the development of embryos after direct waterborne exposure to the NPs. For this, two experiments were run: 1) embryos from unexposed parents were treated for 5days with Ag NPs (10μgAgL(-1)-10mgAgL(-1)) and development was monitored, and 2) selected breeding zebrafish were exposed for 3weeks to 100ngAgL(-1) (environmentally relevant concentration) or to 10μgAgL(-1) of Ag NPs, fecundity was scored and development of resulting embryos was monitored up to 5days. Waterborne exposure of embryos to Ag NPs resulted in being highly toxic (LC50 at 120h=50μgAgL(-1)), causing 100% mortality during the first 24h of exposure at 0.1mgAgL(-1). Exposure of adults, even at the environmentally relevant silver concentration, caused a significant reduction of fecundity by the second week of treatment and resulting embryos showed a higher prevalence of malformations than control embryos. Exposed adult females presented higher prevalence of vacuolization in the liver. These results show that Ag NPs at an environmentally relevant concentration are able to affect population level parameters in zebrafish. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Transmission properties of fluorocarbon polymer-coated silver hollow glass waveguide with tapered section for Er:YAG laser light

    Science.gov (United States)

    Wang, You; Hiraga, Hajime; Miura, Daisuke; Kato, Yuji; Miyagi, Mitsunobu

    1996-11-01

    We have succeeded in fabricating low-loss fluorocarbon polymer (FCP)-coated silver hollow glass waveguides by using a liquid-flow coating method. The thickness of a FCP film is strongly dependent on the flow speed and the concentration of FCP solution. It is shown that the optimum condition exists for depositing the polymer to reduce the roughness of layer. The transmission loss of the fabricated waveguide with inner diameter of 700 micrometers is about 0.2 dB/m for Er:YAG laser light. An efficient tapered coupler with a lens is also investigated to couple the laser beam with large diameter to small-bore waveguides.

  20. Surface silver-doping of biocompatible glasses to induce antibacterial properties. Part II: Plasma sprayed glass-coatings.

    Science.gov (United States)

    Miola, M; Ferraris, S; Di Nunzio, S; Robotti, P F; Bianchi, G; Fucale, G; Maina, G; Cannas, M; Gatti, S; Massé, A; Vitale Brovarone, C; Verné, E

    2009-03-01

    A 57% SiO(2), 3% Al(2)O(3), 34% CaO and 6% Na(2)O glass (SCNA) has been produced in form of powders and deposited by plasma spray on titanium alloy and stainless steel substrates. The obtained coatings have been subjected to a patented ion-exchange treatment to introduce silver ions in the surface inducing an antibacterial behavior. Silver surface-enriched samples have been characterized by means of X-ray diffraction, SEM observation, EDS analysis, in vitro bioactivity tests, leaching tests by GFAAS (graphite furnace atomic adsorption spectroscopy) analyses, cells adhesion and proliferation, and antibacterial tests using Staphylococcus Aureus strain. In vitro tests results showed that the modified samples acquired an antimicrobial action against tested bacteria maintaining unaffected the biocompatibility of the glass. Furthermore the ion-exchange treatment can be successfully applied to glass-coated samples without affecting the properties of the coatings; the simplicity and reproducibility of the method make it suitable for glass or glass-ceramic coatings of different composition in order to produce coated devices for bone healing and/or prostheses, able to reduce bacterial colonization and infections risks.

  1. The electrochemical impedance spectroscopy of silver doped hydroxyapatite coating in simulated body fluid used as corrosive agent

    Directory of Open Access Journals (Sweden)

    Mišković-Stanković Vesna

    2012-01-01

    Full Text Available Titanium is a key biomedical material due its good biocompatibility, mechanical properties and corrosion stability, but infections of the implantation site still pose serious threat. One approach to prevent infection is to improve antimicrobial ability of the coating material. Silver doped hydroxyapatite (Ag/HAP nanoparticles were synthesized by new modified precipitation method. The synthesized powder was used for preparation of Ag/HAP coating on titanium by electrophoretic deposition. The coating was characterized in terms of phase composition and structure by Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR and X-ray diffraction (XRD; surface morphology and chemical composition was assessed using scanning electron microscopy (SEM and energy dispersive spectroscopy (EDS. Research focused on evaluation of the corrosion behaviour of Ag/HAP coating in simulated body fluid (SBF at 37 ºC during prolonged immersion time by electrochemical impedance spectroscopy (EIS. Silver doped HAP coating provided good corrosion protection in SBF solution. [Acknowledgements. This research was financed by the Ministry of Education, Science and Technological Development of the Republic of Serbia, contracts No. III 45019 and by National Sciences and Engineering Research Council of Canada (NSERC. Dr Ana Jankovic was financed by the FP7 Nanotech FTM Grant Agreement 245916

  2. Antibacterial activity of silver nanoparticle-coated fabric and leather against odor and skin infection causing bacteria.

    Science.gov (United States)

    Velmurugan, Palanivel; Lee, Sang-Myeong; Cho, Min; Park, Jung-Hee; Seo, Sang-Ki; Myung, Hyun; Bang, Keuk-Soo; Oh, Byung-Taek

    2014-10-01

    We present a simple, eco-friendly synthesis of silver and gold nanoparticles using a natural polymer pine gum solution as the reducing and capping agent. The pine gum solution was combined with silver nitrate (AgNO3) or a chloroauric acid (HAuCl4) solution to produce silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs), respectively. The reaction process was simple; formation of the nanoparticles was achieved by autoclaving the silver and gold ions with the pine gum. UV-Vis spectra showed surface plasmon resonance (SPR) for silver and gold nanoparticles at 432 and 539 nm, respectively. The elemental forms of AgNPs and AuNPs were confirmed by energy-dispersive X-ray spectroscopy (EDX). Fourier transform infrared spectroscopy (FTIR) showed the biomolecules present in the pine gum, AgNPs, and AuNPs. Transmission electron microscopy (TEM) images showed the shape and size of AgNPs and AuNPs. The crystalline nature of synthesized AgNPs and AuNPs was confirmed by X-ray crystallography [X-ray diffraction (XRD)]. Application of synthesized AgNPs onto cotton fabrics and leather, in order to evaluate their antibacterial properties against odor- or skin infection-causing bacteria, is also discussed. Among the four tested bacteria, AgNP-coated cotton fabric and leather samples displayed excellent antibacterial activity against Brevibacterium linens.

  3. Fabrication of SERS-active substrates using silver nanofilm-coated porous anodic aluminum oxide for detection of antibiotics.

    Science.gov (United States)

    Chen, Jing; Feng, Shaolong; Gao, Fang; Grant, Edward; Xu, Jie; Wang, Shuo; Huang, Qian; Lu, Xiaonan

    2015-04-01

    We have developed a silver nanofilm-coated porous anodic aluminum oxide (AAO) as a surface-enhanced Raman scattering (SERS)-active substrate for the detection of trace level of chloramphenicol, a representative antibiotic in food systems. The ordered aluminum template generated during the synthesis of AAO serves as a patterned matrix on which a coated silver film replicates the patterned AAO matrix to form a 2-dimensional ordered nanostructure. We used atomic force microscopy and scanning electron microscopy images to determine the morphology of this nanosubstrate, and characterized its localized surface plasmon resonance by ultraviolet-visible reflection. We gauged the SERS effect of this nanosubstrate by confocal micro-Raman spectroscopy (782-nm laser), finding a satisfactory and consistent performance with enhancement factors of approximately 2 × 10(4) and a limit of detection for chloramphenicol of 7.5 ppb. We applied principal component analysis to determine the limit of quantification for chloramphenicol of 10 ppb. Using electromagnetic field theory, we developed a detailed mathematical model to explain the mechanism of Raman signal enhancement of this nanosubstrate. With simple sample pretreatment and separation steps, this silver nanofilm-coated AAO substrate could detect 50 ppb chloramphenicol in milk, indicating good potential as a reliable SERS-active substrate for rapid detection of chemical contaminants in agricultural and food products.

  4. Bulk Surfaces Coated with Triangular Silver Nanoplates: Antibacterial Action Based on Silver Release and Photo-Thermal Effect

    Directory of Open Access Journals (Sweden)

    Agnese D’Agostino

    2017-01-01

    Full Text Available A layer of silver nanoplates, specifically synthesized with the desired localized surface plasmon resonance (LSPR features, was grafted on amino-functionalized bulk glass surfaces to impart a double antibacterial action: (i the well-known, long-term antibacterial effect based on the release of Ag+; (ii an “on demand” action which can be switched on by the use of photo-thermal properties of silver nano-objects. Irradiation of these samples with a laser having a wavelength falling into the so called “therapeutic window” of the near infrared region allows the reinforcement, in the timescale of minutes, of the classical antibacterial effect of silver nanoparticles. We demonstrate how using the two actions allows for almost complete elimination of the population of two bacterial strains of representative Gram-positive and Gram-negative bacteria.

  5. Silver hollow optical fibers with acrylic silicone resin coating as buffer layer for sturdy structure

    Science.gov (United States)

    Iwai, Katsumasa; Takaku, Hiroyuki; Miyagi, Mitsunobu; Shi, Yi-Wei; Zhu, Xiao-Song; Matsuura, Yuji

    2016-03-01

    For sturdy silver hollow optical fibers, acrylic silicone resin is newly used as a buffer layer between an inner silver layer and a silica capillary. This acrylic silicone resin film prevents the glass surface from chemical and mechanical micro damages during silver plating process, which deteriorate mechanical strength of the hollow fibers. In addition, it keeps high adhesion of the silver layer with the glass surface. We discuss improvement of mechanical strength of the hollow glass fibers without deterioration of optical properties.

  6. ANTIMICROBIAL PROPERTIES OF HYDROXYAPATITE COATINGS CONTAINING OF CHITOSAN AND SILVER ON TITANIUM SUBSTRATES IN RELATION TO MICROORGANISMS E.COLI ATCC 25922

    Directory of Open Access Journals (Sweden)

    Sukhodub LB

    2013-03-01

    Full Text Available In this work it was studied the antibacterial properties of coatings based on HA, with Chitosan and silver ions additions, produced by substrates termodeposition method from aqueous solutions with varying concentrations of Chitosan (0.025 and 0.1 g/l and silver (1 mg/l as the antimicrobial components as well as three-part cover, consisting of a film of Chitosan, HA and silver. Study on antibacterial properties of composite coatings on the pathogen E.coli ATCC 25922 was held by Spectrophotometric measurement and analysis of optical density of suspensions, containing samples. 3 series of measurements data were averaged. The results showed that the concentration of antimicrobial components have indicated a bacteriostatic effect of coatings on the culture of E. coli AS ATCC 25922 in physiological solution at a temperature of 37 °C. The most effective was the three-part cover consisting of a film of chitosan, HA and silver.

  7. Study on the Thickness Change of Nickel-Plated Layer in Fabrication of the Silver Hollow Nickel Waveguides by the Outer-Coating Method of the Liquid Phase Process

    OpenAIRE

    2016-01-01

    A metallic hollow waveguide is promising fiber for the delivery of laser radiation. Thickness of the nickel plated layer for supporting of the waveguide in fabrication of a dielectric coated silver hollow nickel waveguide is very important factor. In this paper, the change characteristic in the thickness of the nickel plated layer along the length of the silver coated glass mandrel during fabricating the silver hollow nickel waveguide by the outer-coating method of the liquid phase process ha...

  8. Antimicrobial and anti-thrombogenic features combined in hydrophilic surface coatings for skin-penetrating catheters. Synergy of co-embedded silver particles and heparin.

    Science.gov (United States)

    Croes, Sander; Stobberingh, Ellen E; Stevens, Kris N J; Knetsch, Menno L W; Koole, Leo H

    2011-07-01

    Percutaneous (skin-penetrating) catheters such as central venous catheters (CVCs), are used ubiquitously in the treatment of critically ill patients, although it is known that the risks for serious complications, particularly bloodstream infection and thromboembolism, are high. Materials science and engineering offer important new perspectives regarding further improvement of CVCs. A promising approach is the use of synthetic biocompatible hydrogel coatings with both silver particles and heparin embedded therein. Such formulations combine the well-known broad-spectrum antimicrobial features of silver with the anticoagulant activity of immobilized heparin. Previous work revealed that heparin augments antimicrobial activity of silver, while maintaining its anticoagulant function. This study set out to investigate the synergy of heparin and silver in more detail. Exit-challenge tests, experiments on bacterial killing and adherence, as well as in vitro challenge tests with three Staphylococcus aureus strains (one reference strain, and two clinical isolates) consistently showed the synergistic effect. In addition, the impact of changing the coating's hydrophilicity, and changing the silver concentration in the coatings, were examined. The experimental results, taken together and combined with data from the literature, point out that synergy of heparin and silver is best explained by binding of Ag(+) ions to heparin within the swollen coating, followed by release of heparin-Ag(+) complexes upon immersion of the coatings in an aqueous environment such as blood. Possible implications of this work regarding the development of improved/safer CVCs are briefly discussed.

  9. Glycans coated silver nanoparticles induces autophagy and necrosis in HeLa cells

    Science.gov (United States)

    Panzarini, Elisa; Mariano, Stefania; Dini, Luciana

    2015-06-01

    This study reports the induction of autophagy by two concentrations (2×103 or 2×104 NPs/cell) of 30 nm sized β-D-Glucose- and β-D-Glucose/Sucrose-coated silver NanoParticles (AgNPs-G and AgNPs-GS respectively) in HeLa cells treated for 6, 12, 24 and 48 hrs. Cell viability was assessed by Neutral Red (NR) test and morphological evaluation. In addition ROS generation (NBT test) and induction of apoptosis/necrosis (Annexin V/Propidium Iodide-Annexin V/PI staining) and autophagy (Monodansylcadaverine-MDC staining) were evaluated. Cytotoxicity, ROS generation and morphology changes depend on NPs type and amount, and incubation time. As a general result, AgNPs-G are more toxic than AgNPs-GS. Moreover, the lowest AgNPs-GS concentration is ineffective on cell viability and ROS generation. Only 10% and 25% of viable HeLa cells were found at the end of incubation time in the presence of higher amount of AgNPs - G and AgNPs-GS respectively and in parallel ROS generation is induced. To elucidate the type of cell death, Annexin V/PI and MDC staining was performed. Interestingly, irrespective of coating type and NPs amount the percentage of apoptotic cells (Annexin V+/PI-) is similar to viable HeLa cells. At contrary, we observed a NPs amount dependent autophagy and necrosis induction. In fact, the lower amount of NPs induces autophagy (MDC+/PI- cells) whereas the higher one induces necrosis (Annexin V+/PI+ cells). Our findings suggest that AgNPs-induced cytotoxicity depends on AgNPs amount and type and provide preliminary evidence of induction of autophagy in HeLa cells cultured in the presence of AgNPs.

  10. Electrochemical and morphological investigation of silver and zinc modified calcium phosphate bioceramic coatings on metallic implant materials

    Energy Technology Data Exchange (ETDEWEB)

    Furko, M., E-mail: monika.furko@bayzoltan.hu [Bay Zoltán Nonprofit Ltd. for Applied Research, H-1116 Budapest, Fehérvári u. 130 (Hungary); Jiang, Y.; Wilkins, T.A. [Institute of Particle Science and Engineering, University of Leeds, LS2 9JT (United Kingdom); Balázsi, C. [Bay Zoltán Nonprofit Ltd. for Applied Research, H-1116 Budapest, Fehérvári u. 130 (Hungary)

    2016-05-01

    In our research nanostructured silver and zinc doped calcium-phosphate (CaP) bioceramic coatings were prepared on commonly used orthopaedic implant materials (Ti6Al4V). The deposition process was carried out by the pulse current technique at 70 °C from electrolyte containing the appropriate amount of Ca(NO{sub 3}){sub 2} and NH{sub 4}H{sub 2}PO{sub 4} components. During the electrochemical deposition Ag{sup +} and Zn{sup 2+} ions were introduced into the solution. The electrochemical behaviour and corrosion rate of the bioceramic coatings were investigated by potentiodynamic polarization and Electrochemical Impedance Spectroscopy (EIS) measurements in conventional Ringer's solution in a three electrode open cell. The coating came into contact with the electrolyte and corrosion occurred during immersion. In order to achieve antimicrobial properties, it is important to maintain a continuous release of silver ions into physiological media, while the bioactive CaP layer enhances the biocompatibility properties of the layer by fostering the bone cell growth. The role of Zn{sup 2+} is to shorten wound healing time. Morphology and composition of coatings were studied by Scanning Electron Microscopy, Transmission Electron Microscopy and Energy-dispersive X-ray spectroscopy. Differential thermal analyses (DTA) were performed to determine the thermal stability of the pure and modified CaP bioceramic coatings while the structure and phases of the layers were characterized by X-ray diffraction (XRD) measurements. - Highlights: • Ag and Zn doped calcium phosphate (CaP) layers were electrochemically deposited. • Layer degradation was studied by EIS and potentiodynamic measurements. • The bioceramic coatings became passive after a period of immersion time. • Ag and Zn modified layer shows higher degradation rate compared to pure CaP coating.

  11. Plating Layer Structure and Property of Silver-Coated Copper Power with High Silver Content%高银含量银包铜粉镀层结构及性能研究

    Institute of Scientific and Technical Information of China (English)

    胡磊; 朱晓云

    2012-01-01

    采用化学镀法制备具有高银含量、一定厚度、致密性好的银包铜粉,用SEM、XRD、粒度分布仪、数字欧姆表和差热分析仪表征了镀银铜粉和原始铜粉的表面形貌、表面结构及导电性能.结果表明:高银含量银包铜粉表面镀层致密性好、包覆完全,包覆层厚度达到336 nm,同时具有较好的导电性和抗氧化性.%The silver-coated copper powder with high silver content, a silver layer of certain thickness and high density was prepared by chemistry plating reaction. The surface morphology, structure and conductivity of the coated powder and the initial powder were characterized by SEM, XRD, LSPSDA, DOM and TG-DTA. Results show that the surface of the silver-coated copper power with high silver content is dense and coated completely, and the coating thickness is up to 336 nm. The powder has good conductivity and oxidation resistance.

  12. Colloidal stability of carbonate-coated silver nanoparticles in synthetic and natural freshwater.

    Science.gov (United States)

    Piccapietra, Flavio; Sigg, Laura; Behra, Renata

    2012-01-17

    To gain important information on fate, mobility, and bioavailability of silver nanoparticles (AgNP) in aquatic systems, the influence of pH, ionic strength, and humic substances on the stability of carbonate-coated AgNP (average diameter 29 nm) was systematically investigated in 10 mM carbonate and 10 mM MOPS buffer, and in filtered natural freshwater. Changes in the physicochemical properties of AgNP were measured using nanoparticle tracking analysis, dynamic light scattering, and ultraviolet-visible spectroscopy. According to the pH-dependent carbonate speciation, below pH 4 the negatively charged surface of AgNP became positive and increased agglomeration was observed. Electrolyte concentrations above 2 mM Ca(2+) and 100 mM Na(+) enhanced AgNP agglomeration in the synthetic media. In the considered concentration range of humic substances, no relevant changes in the AgNP agglomeration state were measured. Agglomeration of AgNP exposed in filtered natural freshwater was observed to be primarily controlled by the electrolyte type and concentration. Moreover, agglomerated AgNP were still detected after 7 days of exposure. Consequently, slow sedimentation and high mobility of agglomerated AgNP could be expected under the considered natural conditions. A critical evaluation of the different methods used is presented as well.

  13. Strontium incorporation to optimize the antibacterial and biological characteristics of silver-substituted hydroxyapatite coating

    Energy Technology Data Exchange (ETDEWEB)

    Geng, Zhen; Cui, Zhenduo [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Li, Zhaoyang, E-mail: zyli@tju.edu.cn [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Tianjin Key Laboratory of Composite and Functional Materials, Tianjin 300072 (China); Zhu, Shengli [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Tianjin Key Laboratory of Composite and Functional Materials, Tianjin 300072 (China); Liang, Yanqin [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Liu, Yunde; Li, Xue; He, Xin; Yu, Xiaoxu; Wang, Renfeng [School of Laboratory Medicine, Tianjin Medical University, Tianjin 300072 (China); Yang, Xianjin, E-mail: xjyang@tju.edu.cn [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Tianjin Key Laboratory of Composite and Functional Materials, Tianjin 300072 (China)

    2016-01-01

    Infection in primary total joint prostheses is attracting considerable attention. In this study, silver (Ag) was incorporated into hydroxyapatite (HA) using a hydrothermal method in order to improve its antimicrobial properties. Strontium (Sr) was added as a second binary element to improve the biocompatibility. The substituted HA samples were fixed on titanium (Ti) substrates by dopamine-assisted immobilization in order to evaluate their antibacterial and biological properties. The results showed that Ag and Sr were successfully incorporated into HA without affecting their crystallinity. Further, the antibacterial tests showed that all the Ag-substituted samples had good anti-bacterial properties against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Despite their good antibacterial ability, the Ag-substituted samples showed evidence of cytotoxicity on MG63 cells, characterized by low cell density and poor spreadability. The addition of Sr to the Ag-substituted samples considerably reduced the cytotoxicity of Ag. Although the viability of the cells grown on the surfaces of co-substituted HA was not as high as that of the cells grown on the HA surfaces, it is believed that excellent antibacterial properties and good biological activity can be achieved by balancing the dosage of Sr and Ag. - Highlights: • Ag- and Sr-substituted HA was prepared by hydrothermal method. • Ag- and Sr-substituted HA coating was deposited on dopamine functionalized titanium. • Ag-substituted HA biofilm showed a remarkable antibacterial activity. • Sr could offset the side effects of Ag.

  14. Study on the Thickness Change of Nickel-Plated Layer in Fabrication of the Silver Hollow Nickel Waveguides by the Outer-Coating Method of the Liquid Phase Process

    CERN Document Server

    Ro, Sok-Bong; Kim, Uo-Hyon

    2016-01-01

    A metallic hollow waveguide is promising fiber for the delivery of laser radiation. Thickness of the nickel plated layer for supporting of the waveguide in fabrication of a dielectric coated silver hollow nickel waveguide is very important factor. In this paper, the change characteristic in the thickness of the nickel plated layer along the length of the silver coated glass mandrel during fabricating the silver hollow nickel waveguide by the outer-coating method of the liquid phase process has been studied both experimentally and analytically. Waveguides with uniform thickness of the nickel plated layer along the length of the silver coated glass mandrel have been fabricated.

  15. Investigation of coatings of natural organic matter on silver nanoparticles under environmentally relevant conditions by surface-enhanced Raman scattering.

    Science.gov (United States)

    Kühn, Melanie; Ivleva, Natalia P; Klitzke, Sondra; Niessner, Reinhard; Baumann, Thomas

    2015-12-01

    The widespread use of engineered inorganic nanoparticles (EINP) leads to a growing risk for an unintended release into the environment. Despite the good characterization of EINP in regard to their function scale and the application areas, there is still a gap of knowledge concerning their behaviour in the different environmental compartments. Due to their high surface to volume ratio, surface properties and existence or development of a coating are of high importance for their stability and transport behaviour. However, analytical methods to investigate organic coatings on nanoparticles in aqueous media are scarce. We used Raman microspectroscopy in combination with surface-enhanced Raman scattering (SERS) to investigate humic acid coatings on silver nanoparticles under environmentally relevant conditions and in real world samples. This setup is more challenging than previous mechanistic studies using SERS to characterize the humic acids in tailored settings where only one type of organic matter is present and the concentrations of the nanoparticles can be easily adjusted to the experimental needs. SERS offers the unique opportunity to work with little sample preparation directly with liquid samples, thus significantly reducing artefacts. SERS spectra of different natural organic matter brought into contact with silver nanoparticles indicate humic acid in close proximity to the nanoparticles. This coating was also present after several washing steps by centrifugation and resuspension in deionized water and after an increase in ionic strength.

  16. Acute toxicity, bioaccumulation and effects of dietary transfer of silver from brine shrimp exposed to PVP/PEI-coated silver nanoparticles to zebrafish.

    Science.gov (United States)

    Lacave, José María; Fanjul, Álvaro; Bilbao, Eider; Gutierrez, Nerea; Barrio, Irantzu; Arostegui, Inmaculada; Cajaraville, Miren P; Orbea, Amaia

    2017-09-01

    The extensive use and release to the aquatic environment of silver nanoparticles (NPs) could lead to their incorporation into the food web. Brine shrimp larvae of 24h showed low sensitivity to the exposure to PVP/PEI-coated Ag NPs (5nm), with EC50 values at 24h of 19.63mgAgL(-1), but they significantly accumulated silver after 24h of exposure to 100μgL(-1) of Ag NPs. Thus, to assess bioaccumulation and effects of silver transferred by the diet in zebrafish, brine shrimp larvae were exposed to 100ngL(-1) of Ag NPs as an environmentally relevant concentration or to 100μgL(-1) as a potentially effective concentration and used to feed zebrafish for 21days. Autometallography revealed a dose- and time-dependent metal accumulation in the intestine and in the liver of zebrafish. Three-day feeding with brine shrimps exposed to 100ngL(-1) of Ag NPs was enough to impair fish health as reflected by the significant reduction of lysosomal membrane stability and the presence of vacuolization and necrosis in the liver. However, dietary exposure to 100μgL(-1) of Ag NPs for 3days did not significantly alter gene transcription levels, neither in the liver nor in the intestine. After 21days, biological processes such as lipid transport and localization, cellular response to chemical stimulus and response to xenobiotic stimulus were significantly altered in the liver. Overall, these results indicate an effective dietary transfer of silver and point out to liver as the main target organ for Ag NP toxicity in zebrafish after dietary exposure. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Genotoxicity of polyvinylpyrrolidone-coated silver nanoparticles in BEAS 2B cells.

    Science.gov (United States)

    Nymark, Penny; Catalán, Julia; Suhonen, Satu; Järventaus, Hilkka; Birkedal, Renie; Clausen, Per Axel; Jensen, Keld Alstrup; Vippola, Minnamari; Savolainen, Kai; Norppa, Hannu

    2013-11-08

    Silver nanoparticles (AgNPs) are widely utilized in various consumer products and medical devices, especially due to their antimicrobial properties. However, several studies have associated these particles with toxic effects, such as inflammation and oxidative stress in vivo and cytotoxic and genotoxic effects in vitro. Here, we assessed the genotoxic effects of AgNPs coated with polyvinylpyrrolidone (PVP) (average diameter 42.5±14.5 nm) on human bronchial epithelial BEAS 2B cells in vitro. AgNPs were dispersed in bronchial epithelial growth medium (BEGM) with 0.6 mg/ml bovine serum albumin (BSA). The AgNP were partially well-dispersed in the medium and only limited amounts (ca. 0.02 μg Ag(+) ion/l) could be dissolved after 24h. The zeta-potential of the AgNPs was found to be highly negative in pure water but was at least partially neutralized in BEGM with 0.6 mg BSA/ml. Cytotoxicity was measured by cell number count utilizing Trypan Blue exclusion and by an ATP-based luminescence cell viability assay. Genotoxicity was assessed by the alkaline single cell gel electrophoresis (comet) assay, the cytokinesis-block micronucleus (MN) assay, and the chromosomal aberration (CA) assay. The cells were exposed to various doses (0.5-48 μg/cm(2) corresponding to 2.5-240 μg/ml) of AgNPs for 4 and 24 h in the comet assay, for 48 h in the MN assay, and for 24 and 48 h in the CA assay. DNA damage measured by the percent of DNA in comet tail was induced in a dose-dependent manner after both the 4-h and the 24-h exposures to AgNPs, with a statistically significant increase starting at 16 μg/cm(2) (corresponding to 60.8 μg/ml) and doubling of the percentage of DNA in tail at 48 μg/cm(2). However, no induction of MN or CAs was observed at any of the doses or time points. The lack of induction of chromosome damage by the PVP-coated AgNPs is possibly due to the coating which may protect the cells from direct interaction with the AgNPs, either by reducing ion leaching from the

  18. Advanced surface characterization of silver nanocluster segregation in Ag-TiCN bioactive coatings by RBS, GDOES, and ARXPS.

    Science.gov (United States)

    Escobar Galindo, R; Manninen, N K; Palacio, C; Carvalho, S

    2013-07-01

    Surface modification by means of wear protective and antibacterial coatings represents, nowadays, a crucial challenge in the biomaterials field in order to enhance the lifetime of bio-devices. It is possible to tailor the properties of the material by using an appropriate combination of high wear resistance (e.g., nitride or carbide coatings) and biocide agents (e.g., noble metals as silver) to fulfill its final application. This behavior is controlled at last by the outmost surface of the coating. Therefore, the analytical characterization of these new materials requires high-resolution analytical techniques able to provide information about surface and depth composition down to the nanometric level. Among these techniques are Rutherford backscattering spectrometry (RBS), glow discharge optical emission spectroscopy (GDOES), and angle resolved X-ray photoelectron spectroscopy (ARXPS). In this work, we present a comparative RBS-GDOES-ARXPS study of the surface characterization of Ag-TiCN coatings with Ag/Ti atomic ratios varying from 0 to 1.49, deposited at room temperature and 200 °C. RBS analysis allowed a precise quantification of the silver content along the coating with a non-uniform Ag depth distribution for the samples with higher Ag content. GDOES surface profiling revealed that the samples with higher Ag content as well as the samples deposited at 200 °C showed an ultrathin (1-10 nm) Ag-rich layer on the coating surface followed by a silver depletion zone (20-30 nm), being the thickness of both layers enhanced with Ag content and deposition temperature. ARXPS analysis confirmed these observations after applying general algorithm involving regularization in addition to singular value decomposition techniques to obtain the concentration depth profiles. Finally, ARXPS measurements were used to provide further information on the surface morphology of the samples obtaining an excellent agreement with SEM observations when a growth model of silver islands with

  19. Enhancement of the electrical properties of silver nanowire transparent conductive electrodes by atomic layer deposition coating with zinc oxide

    Science.gov (United States)

    Pham, Anh-Tuan; Nguyen, Xuan-Quang; Tran, Duc-Huy; Phan, Vu Ngoc; Duong, Thanh-Tung; Nguyen, Duy-Cuong

    2016-08-01

    Transparent conductive electrodes for applications in optoelectronic devices such as solar cells and light-emitting diodes are important components and require low sheet resistance and high transmittance. Herein, we report an enhancement of the electrical properties of silver (Ag) nanowire networks by coating with zinc oxide using the atomic layer deposition technique. A strong decrease in the sheet resistance of Ag nanowires, namely from 20-40 Ω/□ to 7-15 Ω/□, was observed after coating with ZnO. Ag nanowire electrodes coated with 200-cycle ZnO by atomic layer deposition show the best quality, with a sheet resistance of 11 Ω/□ and transmittance of 75%.

  20. 3,4-Dihydro-1,3-2H-benzoxazines: Novel reducing agents through one electron donation mechanism and their application as the formation of nano-metallic silver coating

    Energy Technology Data Exchange (ETDEWEB)

    Kaewvilai, Attaphon [Department of Materials Engineering, Faculty of Engineering, Kasetsart University, Chatuchak, Bangkok, 10900 (Thailand); Wattanathana, Worawat [Department of Chemistry, Faculty of Science, Kasetsart University, Chatuchak, Bangkok, 10900 (Thailand); Jongrungruangchok, Suchada [Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Rangsit University, Pathumthani, 12000 (Thailand); Veranitisagul, Chatchai [Department of Material and Metallurgical Engineering, Faculty of Engineering, Rajamangala University of Technology Thanyaburi, Klong 6, Thanyaburi, Pathumthani, 12110 (Thailand); Koonsaeng, Nattamon [Department of Chemistry, Faculty of Science, Kasetsart University, Chatuchak, Bangkok, 10900 (Thailand); Laobuthee, Apirat, E-mail: fengapl@ku.ac.th [Department of Materials Engineering, Faculty of Engineering, Kasetsart University, Chatuchak, Bangkok, 10900 (Thailand)

    2015-11-01

    3,4-dihydro-1,3-2H-benzoxazines as novel one-electron donators for silver(I) ion into nano-metallic silver was firstly found and reported. The silver formation from nano-spherical particles to coral-like and dendrite-like structures was presented. With respect to the characterization results, the feasible reaction mechanism of the silver formation was proposed as an electron donated from benzoxazine to silver(I) ion, resulting in a radical cationic species of benzoxazine and silver(0). Based on this reduction process, a new approach for nano-silver coating on various surfaces such as fumed silica (SiO{sub 2}), titanium dioxide (TiO{sub 2}), carbon black (CB), chitosan (CS) including plastic sheet (polycarbonate, PC) and pellet (polyvinyl alcohol, PVA), was also revealed. Besides the nano-silver coated products were applied as antimicrobials fillers for Staphylococcus aureus ATCC 25923, Bacillus subtilis ATCC 6633, Micrococcus luteus ATCC 9341, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 2785 and Candida albicans ATCC 10231. - Highlights: • Benzoxazines were discovered to be novel reducing agents for silver(I) ion. • The speculated mechanism of the one electron donation process was investigated. • Dendrite structure of silver was formed from spherical silver nanoparticles. • A new approach for nano metallic-silver coating on various surfaces was revealed. • The nano-silver coated products were applied as antimicrobials fillers.

  1. Low molecular weight chitosan-coated silver nanoparticles are effective for the treatment of MRSA-infected wounds

    Science.gov (United States)

    Peng, Yinbo; Song, Chenlu; Yang, Chuanfeng; Guo, Qige; Yao, Min

    2017-01-01

    Silver nanoparticles (AgNPs) are being widely applied as topical wound materials; however, accumulated deposition of silver in the liver, spleen, and other main organs may lead to organ damage and dysfunction. We report here that low molecular weight chitosan-coated silver nanoparticles (LMWC-AgNPs) are effective against methicillin-resistant Staphylococcus aureus (MRSA), have better biocompatibility, and have lower body absorption characteristics when compared with polyvinylpyrrolidone-coated silver nanoparticles (PVP-AgNPs) and silver nanoparticles without surface stabilizer (uncoated-AgNPs) in a dorsal MRSA wound infection mouse model. LMWC-AgNPs were synthesized by reducing silver nitrate with low molecular weight chitosan as a stabilizer and reducing agent, while PVP-AgNPs were synthesized using polyvinylpyrrolidone as a stabilizer and ethanol as a reducing agent. AgNPs with different surface stabilizers were identified by UV-visible absorption spectrometry, and particle size was determined by transmission electron microscopy. UV-visible absorption spectra of LMWC-AgNPs, PVP-AgNPs and uncoated-AgNPs were similar and their sizes were in the range of 10–30 nm. In vitro experiments showed that the three types of AgNPs had similar MRSA-killing effects, with obvious effect at 4 μg/mL and 100% effect at 8 μg/mL. Bacteriostatic annulus experiments also showed that all the three types of AgNPs had similar antibacterial inhibitory effect at 10 μg/mL. Cell counting kit-8 assay and Hoechst/propidium iodide (PI) staining showed that LMWC-AgNPs were significantly less toxic to human fibroblasts than PVP-AgNPs and uncoated-AgNPs. Treatment of mice with MRSA wound infection demonstrated that the three types of AgNPs effectively controlled MRSA wound infection and promoted wound healing. After continuous application for 14 days, LMWC-AgNPs-treated mice showed significantly reduced liver dysfunction as demonstrated by the reduced alanine aminotransferase and aspartate

  2. Low molecular weight chitosan-coated silver nanoparticles are effective for the treatment of MRSA-infected wounds.

    Science.gov (United States)

    Peng, Yinbo; Song, Chenlu; Yang, Chuanfeng; Guo, Qige; Yao, Min

    2017-01-01

    Silver nanoparticles (AgNPs) are being widely applied as topical wound materials; however, accumulated deposition of silver in the liver, spleen, and other main organs may lead to organ damage and dysfunction. We report here that low molecular weight chitosan-coated silver nanoparticles (LMWC-AgNPs) are effective against methicillin-resistant Staphylococcus aureus (MRSA), have better biocompatibility, and have lower body absorption characteristics when compared with polyvinylpyrrolidone-coated silver nanoparticles (PVP-AgNPs) and silver nanoparticles without surface stabilizer (uncoated-AgNPs) in a dorsal MRSA wound infection mouse model. LMWC-AgNPs were synthesized by reducing silver nitrate with low molecular weight chitosan as a stabilizer and reducing agent, while PVP-AgNPs were synthesized using polyvinylpyrrolidone as a stabilizer and ethanol as a reducing agent. AgNPs with different surface stabilizers were identified by UV-visible absorption spectrometry, and particle size was determined by transmission electron microscopy. UV-visible absorption spectra of LMWC-AgNPs, PVP-AgNPs and uncoated-AgNPs were similar and their sizes were in the range of 10-30 nm. In vitro experiments showed that the three types of AgNPs had similar MRSA-killing effects, with obvious effect at 4 μg/mL and 100% effect at 8 μg/mL. Bacteriostatic annulus experiments also showed that all the three types of AgNPs had similar antibacterial inhibitory effect at 10 μg/mL. Cell counting kit-8 assay and Hoechst/propidium iodide (PI) staining showed that LMWC-AgNPs were significantly less toxic to human fibroblasts than PVP-AgNPs and uncoated-AgNPs. Treatment of mice with MRSA wound infection demonstrated that the three types of AgNPs effectively controlled MRSA wound infection and promoted wound healing. After continuous application for 14 days, LMWC-AgNPs-treated mice showed significantly reduced liver dysfunction as demonstrated by the reduced alanine aminotransferase and aspartate

  3. Adding Processes of Silver Solution and the Deposit Process of Silver Coating during Reduction Preparation of Silver-Coated Copper Powders%还原法制备银包铜粉主盐添加工艺及镀层沉积过程研究

    Institute of Scientific and Technical Information of China (English)

    赵少凡; 夏志东; 周虎; 刘小黑

    2012-01-01

    The silver-coated copper powders were prepared by a reduction method, using glucose as the reductant. The different adding processes of silver-ammonia solution varied the micro-morphology and appearance color of the powders. The coated powders were characterized by SEM and EDS. The silver contents of different adding processes were calculated by titration. Thus the optimal adding process was determined. Meanwhile, the silver coating deposit process was analyzed by observation of the powders taken out from the solution at different stages during silver plating.%用葡萄糖作为还原剂制备银包铜粉.在还原法镀银过程中,主盐溶液以不同的工艺添加可得到不同微观形貌和表观颜色的银包铜粉,用扫描电镜、能谱仪对银包铜粉进行表征,并用滴定法计算不同添加工艺制备的银包铜粉的含银量,确定了较优的主盐添加工艺;同时,通过在施镀过程中阶段性取粉观察,对银包铜粉镀层的沉积过程进行了分析.

  4. Equine multiple congenital ocular anomalies and silver coat colour result from the pleiotropic effects of mutant PMEL.

    Directory of Open Access Journals (Sweden)

    Lisa S Andersson

    Full Text Available Equine Multiple Congenital Ocular Anomalies (MCOA syndrome is a heritable eye disorder mainly affecting silver colored horses. Clinically, the disease manifests in two distinct classes depending on the horse genotype. Horses homozygous for the mutant allele present with a wide range of ocular defects, such as iris stromal hypoplasia, abnormal pectinate ligaments, megaloglobus, iridociliary cysts and cataracts. The phenotype of heterozygous horses is less severe and predominantly includes iridociliary cysts, which occasionally extend into the temporal retina. In order to determine the genetic cause of MCOA syndrome we sequenced the entire previously characterized 208 kilobase region on chromosome 6 in ten individuals; five MCOA affected horses from three different breeds, one horse with the intermediate Cyst phenotype and four unaffected controls from two different breeds. This was performed using Illumina TruSeq technology with paired-end reads. Through the systematic exclusion of all polymorphisms barring two SNPs in PMEL, a missense mutation previously reported to be associated with the silver coat colour and a non-conserved intronic SNP, we establish that this gene is responsible for MCOA syndrome. Our finding, together with recent advances that show aberrant protein function due to the coding mutation, suggests that the missense mutation is causative and has pleiotrophic effect, causing both the horse silver coat color and MCOA syndrome.

  5. PREPARATION OF TITANIA SOL-GEL COATINGS CONTAINING SILVER IN VARIOUS FORMS AND MEASURING OF THEIR BACTERICIDAL EFFECTS AGAINST E. COLI

    Directory of Open Access Journals (Sweden)

    Diana Horkavcova

    2015-09-01

    Full Text Available The work describes titania coatings containing various forms of silver applied on a titanium substrate by a dip-coating sol-gel technique. Silver was added into the basic titania sol in form of colloid particles of Ag, crystals of AgNO3, particles of AgI, particles of Ag3PO4 and Ag3PO4 developed in situ (in the sol by reaction of AgNO3 with added calcium phosphate (brushite or monetite. Mechanically and chemically treated titanium substrates were dipped at a constant rate into individual types of sols. Subsequently, they were slowly fired. The fired coatings contained microcracks. All over the surface there were evenly distributed spherical nanoparticles of silver (Ag, AgNO3 or microcrystals of AgI and Ag3PO4. The prepared coatings were tested under static conditions for their bactericidal effects against gram-negative bacteria Escherichia coli (E. coli. The coated substrates were immersed into a suspension of E. coli in physiological solution for 24 and 4 hours. The basic titania coatings with no silver demonstrated no bactericidal properties. Very good bactericidal effect against E. coli in both types of bactericidal test showed the titania coatings with AgNO3, Ag3PO4 crystals and Ag3PO4 developed in situ.

  6. Nanostructured titanium-silver coatings with good antibacterial activity and cytocompatibility fabricated by one-step magnetron sputtering

    Science.gov (United States)

    Bai, Long; Hang, Ruiqiang; Gao, Ang; Zhang, Xiangyu; Huang, Xiaobo; Wang, Yueyue; Tang, Bin; Zhao, Lingzhou; Chu, Paul K.

    2015-11-01

    Bacterial infection and loosing are serious complications for biomedical implants in the orthopedic, dental, and other biomedical fields and the ideal implants should combine good antibacterial ability and bioactivity. In this study, nanostructured titanium-silver (Ti-Ag) coatings with different Ag contents (1.2 to 21.6 at%) are prepared on Ti substrates by magnetron sputtering. As the Ag concentration is increased, the coatings change from having dense columnar crystals to sparse ones and eventually no columnar structure. The Ti-Ag coatings can effectively kill Staphylococcus aureus during the first few days and remain moderately antibacterial after immersion for 75 days. Compared to pure Ti, the Ti-Ag coatings show good cytocompatibility as indicated by good osteoblast adhesion, proliferation, intracellular total protein synthesis, and alkaline phosphatase (ALP) activity. In addition, cell spreading, collagen secretion, and extracellular matrix mineralization are promoted on the coatings with the proper Ag contents due to the nanostructured morphological features. Our results indicate that favorable antibacterial activity and osseointegration ability can be simultaneously achieved by regulating the Ag contents in Ti-Ag coatings.

  7. In vitro antimicrobial properties of silver-polysaccharide coatings on porous fiber-reinforced composites for bone implants.

    Science.gov (United States)

    Nganga, Sara; Travan, Andrea; Marsich, Eleonora; Donati, Ivan; Söderling, Eva; Moritz, Niko; Paoletti, Sergio; Vallittu, Pekka K

    2013-12-01

    Biostable fiber-reinforced composite (FRC) implants prepared from bisphenol-A-dimethacrylate and triethyleneglycoldimethacrylate resin reinforced with E-glass fibers have been successfully used in cranial reconstructions in 15 patients. Recently, porous FRC structures were suggested as potential implant materials. Compared with smooth surface, porous surface allows implant incorporation via bone ingrowth, but is also a subject to bacterial attachment. Non-cytotoxic silver-polysaccharide nanocomposite coatings may provide a way to decrease the risk of bacterial contamination of porous FRC structures. This study is focused on the in vitro characterization of the effect porosity on the antimicrobial efficiency of the coatings against Staphylococcus aureus and Pseudomonas aeruginosa by a series of microbiological tests (initial adhesion, antimicrobial efficacy, and biofilm formation). Characterization included confocal laser scanning microscopy and scanning electron microscopy. The effect of porosity on the initial attachment of S. aureus was pronounced, but in the case of P. aeruginosa the effect was negligible. There were no significant effects of the coatings on the initial bacterial attachment. In the antimicrobial efficacy test, the coatings were potent against both strains regardless of the sample morphology. In the biofilm tests, there were no clear effects either of morphology or of the coating. Further coating development is foreseen to achieve a longer-term antimicrobial effect to inhibiting bacterial implant colonization.

  8. One-step polypyrrole coating of self-assembled silver nanoprisms for enhanced stability and Raman scattering

    Science.gov (United States)

    Jeong, Dong-Won; Jeong, Sugyeong; Jang, Du-Jeon

    2017-07-01

    Self-assemblies of silver nanoprisms (AgPRs) having enhanced structural stability and optical properties have been facilely coated with polypyrrole (PPy) via the in situ polymerization of pyrrole monomers that also act as an assembling agent. The assemblies of AgPRs, whose edge lengths and thicknesses are typically 78 and 4 nm, respectively, have been surrounded by a PPy coating of 6 nm. AgPRs are assembled in a side-to-side orientation, and the degree of assembly has been controlled by varying the concentration of trisodium citrate dihydrate, which attaches selectively to the {111} facets of AgPRs. The morphology deformation time of PPy-coated AgPRs in 0.6 mM H2O2(aq) is seven times longer than that of PPy-free AgPRs, suggesting that PPy coating prevents the sharp tips of AgPRs from being truncated by oxidizing agents. The SERS effect of highly self-assembled and PPy-coated AgPRs becomes as high as 6.3 due to numerous hot spots generated between nanoprisms. Overall, our fabricated AgPRs assemblies with PPy coating have not only improved structural stability but also enhanced optical properties, extending the practical use of noble-metal nanoprisms for various optical applications.

  9. Storage Stability of Kinnow Fruit (Citrus reticulata as Affected by CMC and Guar Gum-Based Silver Nanoparticle Coatings

    Directory of Open Access Journals (Sweden)

    Syed Wasim Ahmad Shah

    2015-12-01

    Full Text Available The influence of carboxy methyl cellulose (CMC and guargum-based coatings containing silver nanoparticles was studied on the postharvest storage stability of the kinnow mandarin (Citrus reticulata cv. Blanco for a period of 120 days (85%–90% relative humidity at 4 °C and 10 °C. Physicochemical and microbiological qualities were monitored after every 15 days of storage. Overall results revealed an increase in total soluble solid (TSS, total sugars, reducing sugars and weight loss but this increase was comparatively less significant in coated fruits stored at 4 °C. Ascorbic acid, total phenolics, and antioxidant activity was significantly enhanced in coated fruits stored at 4 °C. Titratable acidity significantly decreased during storage except for coated kinnow stored at 4 °C. In control samples stored at 10 °C, high intensity of fruit rotting and no chilling injury was observed. Total aerobic psychrotrophic bacteria and yeast and molds were noticed in all treatments during storage but the growth was not significant in coated fruits at 4 °C. Kinnow fruit can be kept in good quality after coating for four months at 4 °C and for 2 months at 10 °C.

  10. Voltammetric determination of theophylline at a Nafion/multi-wall carbon nanotubes composite film-modified glassy carbon electrode

    Indian Academy of Sciences (India)

    Suling Yang; Ran Yang; Gang Li; Jianjun Li; Lingbo Qu

    2010-11-01

    A Nafion/multi-wall carbon nanotubes (MWNTs) composite film-modified electrode was fabricated and applied to the sensitive and convenient determination of theophylline (TP). Multi-wall carbon nanotubes (MWNTs) were easily dispersed homogeneously into 0.1% Nafion methanol solution by sonication. Appropriate amount of Nafion/MWNTs suspension was coated on a glassy carbon electrode. After evaporating methanol, a Nafion/MWNTs composite film-modified electrode was achieved. TP could effectively accumulate at Nafion/MWNTs composite film-modified electrode and cause a sensitive anodic peak at around 1180 mV (vs SCE) in 0.01 mol/L H2SO4 medium (pH 1.8). In contrast with the bare glassy carbon electrode, Nafion film-modified electrode, Nafion/MWNTs film-modified electrode could remarkably increase the anodic peak current and decreased the overpotential of TP oxidation. Under the optimized conditions, the anodic peak current was proportional to TP concentration in the range of 8.0 × 10-8-6.0 × 10-5 mol/L, with a detection limit of 2.0 × 10-8 mol/L. This newly developed method was used to determine TP in drug samples with good percentage of recoveries.

  11. Sonochemical coating of silver nanoparticles on textile fabrics (nylon, polyester and cotton) and their antibacterial activity

    Energy Technology Data Exchange (ETDEWEB)

    Perelshtein, Ilana; Applerot, Guy; Perkas, Nina; Gedanken, Aharon [Department of Chemistry, Kanbar Laboratory for Nanomaterials, Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 52900 (Israel); Guibert, Geoffrey; Mikhailov, Serguei [Haute Ecole Arc Ingenierie IMA-Arc, NEODE, 17 Eplatures-Grise, CH-2300 La Chaux-de-Fonds (Switzerland)], E-mail: gedanken@mail.biu.ac.il

    2008-06-18

    Silver nanoparticles were synthesized and deposited on different types of fabrics using ultrasound irradiation. The structure of silver-fabric composites was studied by physico-chemical methods. The mechanism of the strong adhesion of silver nanoparticles to the fibers is discussed. The excellent antibacterial activity of the Ag-fabric composite against Escherichia coli (gram-negative) and Staphylococcus aureus (gram-positive) cultures was demonstrated.

  12. On the Use of the Electrospinning Coating Technique to Produce Antimicrobial Polyhydroxyalkanoate Materials Containing In Situ-Stabilized Silver Nanoparticles

    Directory of Open Access Journals (Sweden)

    Jinneth Lorena Castro-Mayorga

    2016-12-01

    Full Text Available Electro-hydrodynamic processing, comprising electrospraying and electrospinning techniques, has emerged as a versatile technology to produce nanostructured fiber-based and particle-based materials. In this work, an antimicrobial active multilayer system comprising a commercial polyhydroxyalkanoate substrate (PHA and an electrospun PHA coating containing in situ-stabilized silver nanoparticles (AgNPs was successfully developed and characterized in terms of morphology, thermal, mechanical, and barrier properties. The obtained materials reduced the bacterial population of Salmonella enterica below the detection limits at very low silver loading of 0.002 ± 0.0005 wt %. As a result, this study provides an innovative route to generate fully renewable and biodegradable materials that could prevent microbial outbreaks in food packages and food contact surfaces.

  13. Effect of thermal treatments on sputtered silver nanocluster/silica composite coatings on soda-lime glasses: ionic exchange and antibacterial activity

    Energy Technology Data Exchange (ETDEWEB)

    Ferraris, M.; Ferraris, S., E-mail: sara.ferraris@polito.it; Miola, M.; Perero, S.; Balagna, C.; Verne, E. [Politecnico di Torino, Department of Applied Science and Technology, Institute of Materials Physics and Engineering (Italy); Gautier, G. [IMAMOTER Institute for Agricultural and Earthmoving Machines (Italy); Manfredotti, Ch.; Battiato, A.; Vittone, E. [University of Torino, Physics Department, NIS Excellence Centre and CNISM (Italy); Speranza, G. [Fondazione Bruno Kessler FBK (Italy); Bogdanovic, I. [Ruder Boskovic Institute, Experimental Physics Department (Croatia)

    2012-12-15

    Silver nanocluster/silica composite coatings were deposited on both soda-lime and silica glasses by radio frequency (RF) co-sputtering. The effect of thermal treatments on the microstructure in the range of 150-450 Degree-Sign C were examined by UV-visible spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and Time of Flight-Elastic Recoil Detection Analysis. Sodium/silver ionic exchange was evidenced for coatings sputtered on soda-lime substrates after heating at 450 Degree-Sign C; presence of silver ions and/or silver nanoclusters, nanocluster size and their position inside the sputtered layers will be discussed for as-deposited and heated coatings on both substrates. The antibacterial activity of all coatings was determined against Staphylococcus aureus and Candida albicans by disk diffusion method and colonies forming units count; in agreement with microstructural results, the antibacterial activity present on all coatings was slightly reduced after heating at 450 Degree-Sign C. All coatings have been submitted to humidity plus UV ageing and sterilization by autoclave, gamma ray and ethylene oxide gas. Tape resistance (ASTM D3359-97) tests have been done on each coating before and after ageing and sterilizations, revealing a good adhesion on soda-lime substrates, except for those aged in humidity plus UV and sterilized by autoclave. Scratch tests and nanoindentation tests have been done on each coating, as-deposited and after heating at 450 Degree-Sign C. The coating hardness was improved by heating only when coatings were deposited on silica. The heating of coatings deposited on soda-lime substrates gave opposite effect on their hardness.

  14. Immobilization of Nafion-ordered mesoporous carbon on a glassy carbon electrode: Application to the detection of epinephrine

    Energy Technology Data Exchange (ETDEWEB)

    Zhou Ming [Faculty of Chemistry, Northeast Normal University, Renmin Street 5268, Changchun 130024 (China); Guo Liping [Faculty of Chemistry, Northeast Normal University, Renmin Street 5268, Changchun 130024 (China)], E-mail: guolp078@nenu.edu.cn; Hou Ying; Peng Xiaojuan [Faculty of Chemistry, Northeast Normal University, Renmin Street 5268, Changchun 130024 (China)

    2008-05-01

    A stable suspension of ordered mesoporous carbon (OMC) was obtained by dispersing OMC in a solution of Nafion. By coating the suspension onto glassy carbon (GC) electrode, cyclic voltammetry was used to evaluate the electrochemical behaviors of Nafion-OMC-modified GC (Nafion-OMC/GC) electrode in 0.1 mmol L{sup -1} hexaammineruthenium(III) chloride (Ru(NH{sub 3}){sub 6}Cl{sub 3})/0.1 mol L{sup -1} KCl solution, where Nafion-OMC/GC electrode shows a faster electron transfer rate as compared with OMC/GC, Nafion/GC and GC electrodes. Due to the unique properties of Nafion-OMC, an obvious decrease in the overvoltage of the epinephrine (EP) oxidation (ca. 100 mV at pH 4.1 and 115 mV at pH 7.0) as well as a dramatic increase in the peak current (12 times at pH 4.1 and 6 times at pH 7.0) was observed at Nafion-OMC/GC electrode compared to that seen at GC electrode. By combining the advantages of OMC with those of Nafion, the anodic peak of EP and that of ascorbic acid (AA) were separated successfully (by ca. 144-270 mV) in the pH range of 2.0-10.0, which may make Nafion-OMC/GC electrode potential for selective determination of EP in the presence of AA at a broad pH range. As an EP sensor, the EP amperometric response at Nafion-OMC/GC electrode in pH 7.0 PBS is extremely stable, with 99% of the initial activity remaining (compared to 32% at GC surface) after 120 min stirring of 0.20 mmol L{sup -1} EP. And Nafion-OMC/GC electrode can be used to readily detect the physiological concentration of EP at pH 7.0. These make Nafion-OMC/GC electrode potential candidates for stable and efficient electrochemical sensor for the detection of EP. The solubilization of OMC by Nafion may provide a route to more precise manipulation, and functionalization for the construction of OMC-based sensors, as well as allowing OMC to be introduced to biologically relevant systems.

  15. Silver-doped nanocomposite carbon coatings (Ag-DLC) for biomedical applications – Physiochemical and biological evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Bociaga, Dorota, E-mail: dorota.bociaga1@gmail.com [Division of Biomedical Engineering and Functional Materials, Lodz University of Technology, Institute of Materials Science and Engineering, 1/15 Stefanowskiego St., 90-924 Lodz (Poland); Komorowski, Piotr [Division of Biophysics, Lodz University of Technology, Institute of Materials Science and Engineering, 1/15 Stefanowskiego St., 90-924 Lodz (Poland); BioNanoPark Laboratories of Lodz Regional Park of Science and Technology, Lodz (Poland); Batory, Damian [Division of Biomedical Engineering and Functional Materials, Lodz University of Technology, Institute of Materials Science and Engineering, 1/15 Stefanowskiego St., 90-924 Lodz (Poland); Szymanski, Witold [Division of Biophysics, Lodz University of Technology, Institute of Materials Science and Engineering, 1/15 Stefanowskiego St., 90-924 Lodz (Poland); Olejnik, Anna; Jastrzebski, Krzysztof [Division of Biomedical Engineering and Functional Materials, Lodz University of Technology, Institute of Materials Science and Engineering, 1/15 Stefanowskiego St., 90-924 Lodz (Poland); Jakubowski, Witold [Division of Biophysics, Lodz University of Technology, Institute of Materials Science and Engineering, 1/15 Stefanowskiego St., 90-924 Lodz (Poland)

    2015-11-15

    Graphical abstract: - Highlights: • The DLC coatings with interlayer improving adhesion were manufactured using the author's method in dual RF/MS PCVD system. • The Ag ions were incorporated into DLC matrix using ion beam implantation method. • The morphology, chemical structure and composition of coatings were examined. • Viability, cytotoxicity of human cells and the formation of bacterial biofilm on the samples surface were evaluated. • <5% of Ag in DLC coating is efficient to make it bactericidal and biocompatible. - Abstract: The formation of bacteria biofilm on the surface of medical products is a major clinical issue nowadays. Highly adaptive ability of bacteria to colonize the surface of biomaterials causes a lot of infections. This study evaluates samples of the AISI 316 LVM with special nanocomposite silver-doped (by means of ion implantation) diamond-like carbon (DLC) coating prepared by hybrid RF/MS PACVD (radio frequency/magnetron sputtering plasma assisted chemical vapour deposition) deposition technique in order to improve the physicochemical and biological properties of biomaterials and add new features such as antibacterial properties. The aim of the following work was to evaluate antimicrobial efficacy and biocompatibility of gradient a-C:H/Ti + Ag coatings in relation to the physiochemical properties of the surface and chemical composition of coating. For this purpose, samples were tested in live/dead test using two cell strains: human endothelial cells (Ea.hy926) and osteoblasts-like cells (Saos-2). For testing bactericidal activity of the coatings, an exponential growth phase of Escherichia coli strain DH5α was used as a model microorganism. Surface condition and its physicochemical properties were investigated using SEM, AFM and XPS. Examined coatings showed a uniformity of silver ions distribution in the amorphous DLC matrix, good biocompatibility in contact with mammalian cells and an increased level of bactericidal

  16. Fabrication of electrically conductive nickel-silver bimetallic particles via polydopamine coating.

    Science.gov (United States)

    Kim, Sung Yeop; Kim, Jieun; Choe, Jaehoon; Byun, Young Chang; Seo, Jung Hyun; Kim, Do Hyun

    2013-11-01

    Inspired by adhesive proteins excreted by marine mussels, dopamine can act as a versatile surface modification agent for various organic and inorganic materials. By using adhesive polydopamine (PDA) as an intermediate layer, a simple and novel method for fabricating nickel-PDA-silver (Ni-PDA-Ag) bimetallic composite particles was developed. Ni-PDA-Ag bimetallic particles were fabricated by dispersing Ni particles in an aqueous dopamine solution followed by electroless Ag plating on the prepared Ni-PDA particles. A PDA layer with nano-meter thickness was deposited spontaneously on the surface of the Ni particles by oxidative self-polymerization of dopamine under alkaline conditions. Electroless Ag plating on the prepared Ni-PDA particles was carried out in the presence of a glucose solution as a reducing agent. Ni-PDA particles and Ni-PDA-Ag composite particles with a PDA intermediate layer were characterized by X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared (FT-IR) spectroscopy, field-emission scanning electron microscopy (FE-SEM), field-emission transmission electron microscopy (FE-TEM), and X-ray diffraction (XRD). In addition, the electrical conductivity of as-prepared composite particles was evaluated by a 4-point probe. The PDA layer deposited on the surface of Ni was confirmed by XPS spectra, FT-IR spectroscopy, and FE-TEM. FE-SEM images demonstrated that Ag nanoparticles were successfully plated on the PDA layer-coated Ni particles after the electroless Ag plating process. XRD patterns also confirmed the presence of Ag in a metallic state. In addition, the sheet resistance of as-prepared composite particles showed a tendency to decrease with increasing AgNO3 concentration.

  17. Photocatalytic and biocidal activities of novel coating systems of mesoporous and dense TiO₂-anatase containing silver nanoparticles.

    Science.gov (United States)

    Roldán, María V; de Oña, Paula; Castro, Yolanda; Durán, Alicia; Faccendini, Pablo; Lagier, Claudia; Grau, Roberto; Pellegri, Nora S

    2014-10-01

    Here we describe the development of novel nanostructured coating systems with improved photocatalytic and antibacterial activities. These systems comprise a layer of SiO2 followed by a layer of mesoporous or dense TiO2-anatase, and doping with silver nanoparticles (Ag NPs). The coatings were synthesized via a sol-gel technique by combining colloidal Ag NPs with TiO2 and SiO2 sols. The photocatalytic activity was studied through methyl orange decomposition under UV light. Results showed a great increase of photocatalytic activity by Ag NPs doping. The most active photocatalyst corresponded to the Ag-SiO2/TiO2 mesoporous system, associated with the porosity of the coatings and with the decrease of e-h recombination for the presence of Ag NPs. All the TiO2 coatings showed a strong bactericidal activity against planktonic forms of Gram-negative (enterohemorrhagic Escherichia coli) and Gram-positive (Listeria monocytogenes) pathogens, as well as a strong germicidal effect against deadly spores of human gas gangrene- and anthrax-producing bacteria (Clostridium perfringens and Bacillus anthracis, respectively). The bactericidal and sporocidal activity was improved by doping the coatings with Ag NPs, even more when nanoparticles were in the outer layer of TiO2, because they are more accessible to the environment. The mechanisms responsible for the increase of photocatalytic and bactericidal behaviors related to Ag NP doping were studied by spectroscopic ellipsometry, UV-vis spectroscopy, photoluminescence and anodic stripping voltammetry. It was found that the separation of the electron-hole pair contributed to the enhancement of photocatalysis, whereas the effect of the local electric field reinforcement was probably present. A possible involvement of a decrease of band-gap energy and dispersion by silver nanoparticles is ruled out. bactericidal efficacy was increased by Ag(+) ion release. Overall, the results included in this article show that the architecture of the

  18. Lysozyme-coated silver nanoparticles for differentiating bacterial strains on the basis of antibacterial activity

    Science.gov (United States)

    Ashraf, Sumaira; Chatha, Mariyam Asghar; Ejaz, Wardah; Janjua, Hussnain Ahmed; Hussain, Irshad

    2014-10-01

    Lysozyme, an antibacterial enzyme, was used as a stabilizing ligand for the synthesis of fairly uniform silver nanoparticles adopting various strategies. The synthesized particles were characterized using UV-visible spectroscopy, FTIR, dynamic light scattering (DLS), and TEM to observe their morphology and surface chemistry. The silver nanoparticles were evaluated for their antimicrobial activity against several bacterial species and various bacterial strains within the same species. The cationic silver nanoparticles were found to be more effective against Pseudomonas aeruginosa 3 compared to other bacterial species/strains investigated. Some of the bacterial strains of the same species showed variable antibacterial activity. The difference in antimicrobial activity of these particles has led to the conclusion that antimicrobial products formed from silver nanoparticles may not be equally effective against all the bacteria. This difference in the antibacterial activity of silver nanoparticles for different bacterial strains from the same species may be due to the genome islands that are acquired through horizontal gene transfer (HGT). These genome islands are expected to possess some genes that may encode enzymes to resist the antimicrobial activity of silver nanoparticles. These silver nanoparticles may thus also be used to differentiate some bacterial strains within the same species due to variable silver resistance of these variants, which may not possible by simple biochemical tests.

  19. Antibacterial properties of a self-cured acrylic resin composed of a polymer coated with a silver-containing organic composite antibacterial agent.

    Science.gov (United States)

    Kiriyama, Takashi; Kuroki, Kenjiro; Sasaki, Keisuke; Tomino, Masahumi; Asakura, Masaki; Kominami, Yoshiko; Takahashi, Yoshihumi; Kawai, Tatsushi

    2013-01-01

    A novel antibacterial polymer, coated with a silver-containing organic composite antibacterial agent, was dispersed in a self-cured acrylic resin. Residual viable cell count of each oral bacterial and fungal species cultivated on acrylic resin specimens containing the antibacterial polymer was significantly decreased when compared to those cultivated on specimens prepared from untreated polymer. A strong inverse correlation was found between the amount of eluted silver ions and the residual viable cell count of all species grown on the antibacterial polymer: the lower the viable cell count, the higher the amount of eluted silver ions. This clearly indicated the antibacterial activity of silver ions. As the content of organic composite antibacterial agent added to the polymer increased from 0.5% to 1.5% in 0.5% increments, amount of eluted silver ions significantly increased with each 0.5% increment to exert greater antibacterial effect.

  20. Biocompatibility versus peritoneal mesothelial cells of polypropylene prostheses for hernia repair, coated with a thin silica/silver layer.

    Science.gov (United States)

    Muzio, Giuliana; Perero, Sergio; Miola, Marta; Oraldi, Manuela; Ferraris, Sara; Vernè, Enrica; Festa, Federico; Canuto, Rosa Angela; Festa, Valentino; Ferraris, Monica

    2017-08-01

    Hernias are generally repaired using synthetic prostheses. Infection may already be present or develop during implantation. Based on the increasing resistance to antibiotics, and the well-known antimicrobial properties of silver (Ag), the possibility of coating hernia prostheses with a nanostructured layer containing Ag was explored. Prostheses (Clear Mesh Composite [CMC]) made up of two polypropylene layers (macroporous light mesh and thin transparent film) were tested with human mesothelial cells from omentum biopsies. Mesotheliocytes modulate abdominal wall healing producing cytokines, growth factors, and adhesion molecules. Evaluating the growth of these cells on CMC or film alone showed that cell numbers on CMC increased over time, and were higher than those on film alone. Vimentin immunostaining confirmed the cells to be mesotheliocytes. Subsequently, the biocompatibility of mesh layer, coated or not with a thin layer of Ag/SiO2 -nanoclusters, was analyzed, showing no difference in absence or presence of Ag/SiO2 . Differently, TGF-β2 production, involved in tissue repair and fibrosis, increased in the presence of Ag/SiO2 . Moreover, Ag/SiO2 -coated mesh showed antibacterial properties. In conclusion, the mesh layer coated with Ag/SiO2 afforded cell growth, and showed antibacterial activity. Coating only the mesh layer did not decrease film transparency, and did not favor the formation of adhesions on the visceral side. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1586-1593, 2017. © 2016 Wiley Periodicals, Inc.

  1. Merit and demerit effects of silver nanoparticles in the bioperformance of an electrodeposited hydroxyapatite: nanosilver composite coating

    Energy Technology Data Exchange (ETDEWEB)

    Ionita, D., E-mail: md_ionita@yahoo.com; Dilea, M., E-mail: mirela_dilea@yahoo.com [University Politehnica of Bucharest, Faculty of Applied Chemistry and Materials Science (Romania); Titorencu, I., E-mail: irina.titorencu@icbp.ro [Institute of Cellular Biology and Pathology (Romania); Demetrescu, I., E-mail: i_demetrescu@chim.upb.ro [University Politehnica of Bucharest, Faculty of Applied Chemistry and Materials Science (Romania)

    2012-10-15

    For this research, TiAlZr specimens were covered with a hydroxyapatite-silver nanoparticles composite coatings (nAg-HA) prepared by pulse electrodeposition. The morphological texture of the nAg-HA nanoparticles on TiAlZr surface was investigated with scanning electron microscopy and energy dispersive X-ray spectroscopy. Electrochemical parameters from dynamic polarization tests performed in Ringer's solution indicate better anticorrosive properties for the TiAlZr alloy after nAg-HA electrodeposition. Bacteriological experiments performed in vitro demonstrate the efficacy of TiAlZr implants coated with nAg-HA against the growth of Escherichia coli bacteria quantified in a 98 % inhibition of Escherichia coli growth. The biocompatibility tests regarding cell adherence, proliferation, and viability of coating (also by means of Reverse Transcription Polymerase Chain Reaction-RT-PCR) completed the characterization of the coating, enabling us to discuss the merit and demerit effects of Ag nanoparticles (nAg) effects on bioperformance. Based on experimental and literature data, the coating could be considered a passive-active structure.

  2. Merit and demerit effects of silver nanoparticles in the bioperformance of an electrodeposited hydroxyapatite: nanosilver composite coating

    Science.gov (United States)

    Ionita, D.; Dilea, M.; Titorencu, I.; Demetrescu, I.

    2012-10-01

    For this research, TiAlZr specimens were covered with a hydroxyapatite-silver nanoparticles composite coatings (nAg-HA) prepared by pulse electrodeposition. The morphological texture of the nAg-HA nanoparticles on TiAlZr surface was investigated with scanning electron microscopy and energy dispersive X-ray spectroscopy. Electrochemical parameters from dynamic polarization tests performed in Ringer's solution indicate better anticorrosive properties for the TiAlZr alloy after nAg-HA electrodeposition. Bacteriological experiments performed in vitro demonstrate the efficacy of TiAlZr implants coated with nAg-HA against the growth of Escherichia coli bacteria quantified in a 98 % inhibition of Escherichia coli growth. The biocompatibility tests regarding cell adherence, proliferation, and viability of coating (also by means of Reverse Transcription Polymerase Chain Reaction—RT-PCR) completed the characterization of the coating, enabling us to discuss the merit and demerit effects of Ag nanoparticles (nAg) effects on bioperformance. Based on experimental and literature data, the coating could be considered a passive-active structure.

  3. Initial study of sediment antagonism and characteristics of silver nanoparticle-coated biliary stents in an experimental animal model

    Directory of Open Access Journals (Sweden)

    Tian Y

    2016-04-01

    Full Text Available Yigeng Tian,1,* Mingfeng Xia,2,* Shuai Zhang,3 Zhen Fu,4 Qingbin Wen,2 Feng Liu,4 Zongzhen Xu,4 Tao Li,4 Hu Tian4 1Department of Physics, School of Physics and Technology, University of Jinan, Jinan, Shandong, People’s Republic of China; 2Department of Surgery, Shandong University of Traditional Chinese Medicine, Jinan, Shandong, People’s Republic of China; 3Department of General Surgery, Sixth People’s Hospital of Jinan, Jinan, Shandong, People’s Republic of China; 4Department of General Surgery, Shandong Provincial Qianfoshan Hospital, Shandong University, Jinan, Shandong, People’s Republic of China *These authors contributed equally to this work Objective: Plastic biliary stents used to relieve obstructive jaundice are frequently blocked by sediment, resulting in loss of drainage. We prepared stents coated with silver nanoparticles (AgNPs and compared their ability to resist sedimentation with Teflon stents in a beagle model of obstructive jaundice.Methods: AgNP-coated Teflon biliary stents were prepared by chemical oxidation–reduction and evaluated in an obstructive jaundice model that was produced by ligation of common bile duct (CBD; animals were randomized to two equal groups for placement of AgNP-coated or Teflon control stents. Liver function and inflammatory index were found to be similar in the two groups, and the obstruction was relieved. Stents were removed 21 days after insertion and observed by scanning and transmission electron microscopy. The AgNP coating was analyzed by energy dispersive X-ray analysis (EDXA, and the composition of sediment was assayed by Fourier-transform infrared (FTIR spectroscopy.Results: Electron microscopy revealed a black, closely adherent AgNP stent coating, with thicknesses of 1.5–6 µm. Sediment thickness and density were greater on Teflon than on AgNP-coated stents. EDXA confirmed the stability and integrity of the AgNP coating before and after in vivo animal experimentation. FTIR

  4. Tip-enhanced Raman spectroscopy with silver-coated optical fiber probe in reflection mode for investigating multiwall carbon nanotubes.

    Science.gov (United States)

    Wang, Rui; Wang, Jia; Hao, Fenghuan; Zhang, Mingqian; Tian, Qian

    2010-04-01

    We developed a tip-enhanced Raman spectrometer (TERS) with reflection mode. The instrument, with a scanning shear-force microscope (ShFM) and a side-illumination Raman spectroscope, can overcome the diffraction limit and has high sensitivity. A chemical method to fabricate optical fiber probes with Ag coating is proposed. The local electromagnetic responses of the silver-coated optical fiber probe are numerically analyzed by the finite-difference time-domain method, and the excitation wavelength is optimized to resonate with the localized surface plasmons (LSP) of the probe tip. The instrument is applied to investigate a single multiwall carbon nanotube. The experiment results indicate that our TERS instrument has a spatial resolution better than 70 nm, and the enhancement factor is about 5 x 10(3).

  5. 镀银锦纶针织面料的质量控制%Quality Control for Silver-coated Polyamide Fabrics

    Institute of Scientific and Technical Information of China (English)

    杨秀芳; 柯华

    2013-01-01

    In this article, it points out that broken yarns, fabric hole and color difference due to oxidation often occur in the knitting of silver-coated polyamide fabric. The corresponding solutions are proposed, which are:handle with care for silver-coated polyamide fibers to reduce rub; try best to shorten the working distance of silver-coated polyamide fibers in knitting machines; soak silver-coated polyamide fibers in knitting oil rapidly and place for 24 h then using; classify silver-coated polyamide fibers with different color due to oxidation and use silver-coated polyamide fibers with the same color in one fabric; and so on. In dyeing and finishing process of silver-coated polyamide fabric, it should try best to treat this kind of fabrics under low temperature with shorten time, meanwhile, it is better to use nonionic detergents to washing. The results show that after dyeing and finishing in the proposed condition, silver-coated polyamide fabrics have high antibacterial property.%文中指出了锦纶镀银纤维在织造中存在断纱、坯布洞眼、氧化色差等问题,提出了相应的解决办法,包括轻拿轻放镀银丝,减少摩擦;尽量缩短其与织机的距离;使用前用针织油快速浸泡镀银丝并放置24 h后再使用;如若由于银的氧化而产生了色差,应对镀银丝再进行分色,同批布中应尽量使用无色差的镀银丝等等。在染整加工过程中,应尽量做到低温少时,并使用非离子性洗涤液对其进行洗涤。检测数据证明,经建议的织造和染整条件加工后,镀银丝针织面料具有较少的织造疵点和良好的抗菌效果。

  6. Size and Aging Effects on Antimicrobial Efficiency of Silver Nanoparticles Coated on Polyamide Fabrics Activated by Atmospheric DBD Plasma.

    Science.gov (United States)

    Zille, Andrea; Fernandes, Margarida M; Francesko, Antonio; Tzanov, Tzanko; Fernandes, Marta; Oliveira, Fernando R; Almeida, Luís; Amorim, Teresa; Carneiro, Noémia; Esteves, Maria F; Souto, António P

    2015-07-01

    This work studies the surface characteristics, antimicrobial activity, and aging effect of plasma-pretreated polyamide 6,6 (PA66) fabrics coated with silver nanoparticles (AgNPs), aiming to identify the optimum size of nanosilver exhibiting antibacterial properties suitable for the manufacture of hospital textiles. The release of bactericidal Ag(+) ions from a 10, 20, 40, 60, and 100 nm AgNPs-coated PA66 surface was a function of the particles' size, number, and aging. Plasma pretreatment promoted both ionic and covalent interactions between AgNPs and the formed oxygen species on the fibers, favoring the deposition of smaller-diameter AgNPs that consequently showed better immediate and durable antimicrobial effects against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria. Surprisingly, after 30 days of aging, a comparable bacterial growth inhibition was achieved for all of the fibers treated with AgNPs <100 nm in size. The Ag(+) in the coatings also favored the electrostatic stabilization of the plasma-induced functional groups on the PA66 surface, thereby retarding the aging process. At the same time, the size-related ratio (Ag(+)/Ag(0)) of the AgNPs between 40 and 60 nm allowed for the controlled release of Ag(+) rather than bulk silver. Overall, the results suggest that instead of reducing the size of the AgNPs, which is associated with higher toxicity, similar long-term effects can be achieved with larger NPs (40-60 nm), even in lower concentrations. Because the antimicrobial efficiency of AgNPs larger than 30 nm is mainly ruled by the release of Ag(+) over time and not by the size and number of the AgNPs, this parameter is crucial for the development of efficient antimicrobial coatings on plasma-treated surfaces and contributes to the safety and durability of clothing used in clinical settings.

  7. Comparative study on microstructure, crystallite size and lattice strain of as-deposited and thermal treatment silver silicon nitride coating on Ti6Al4V alloy

    Science.gov (United States)

    Zalilah, Umi; Mahmoodian, R.

    2017-06-01

    Silver silicon nitride coating were deposited on Ti6Al4V alloy using physical vapor deposition magnetron sputtering technique. Field Emission Spectroscopy (FESEM), Electron Dispersive Spectroscopy (EDS) and X-ray diffraction (XRD) were used to characterize as-deposited and after heat treatment of AgSiN coatings in order to understand the morphology, compositions and structure. Meanwhile, in determining the crystallite size and lattice strain, the simplified Williamson-Hall plot method was utilized. The heat treated coated sample shown to reveal granular surface structure, bigger crystallite size and lattice strain as compared to the as-deposited coated sample.

  8. Preventing infection of osseointegrated transcutaneous implants: Incorporation of silver into preconditioned fibronectin-functionalized hydroxyapatite coatings suppresses Staphylococcus aureus colonization while promoting viable fibroblast growth in vitro.

    Science.gov (United States)

    Chimutengwende-Gordon, Mukai; Pendegrass, Catherine; Bayston, Roger; Blunn, Gordon

    2014-09-01

    The success of transcutaneous implants depends on the achievement of a soft tissue seal by enabling fibroblasts to win the race for the surface against bacteria. Fibronectin-functionalized hydroxyapatite coatings (HAFn) have been shown to improve dermal tissue ingrowth and attachment. However, during the early postoperative period before a soft tissue seal has formed, bacterial colonization may occur. This study explored the incorporation of silver, a broad spectrum antimicrobial agent, into HAFn coatings with the aim of reducing bacterial colonization. Silver is known to have dose-dependent cytotoxic effects. Therefore, the effects of silver incorporation into HAFn coatings on both in vitro human dermal fibroblast viability and Staphylococcus aureus colonization were assessed. An electrochemical deposition technique was used to codeposit hydroxyapatite and silver (HAAg) and fibronectin was adsorbed onto this to produce HAAgFn coatings. Surfaces were preconditioned with serum to mimic the in vivo environment. Nonpreconditioned HAAg and HAAgFn coatings suppressed bacterial colonization but were cytotoxic. After serum-preconditioning, more than 90% of fibroblasts that grew on all HAAg and HAAgFn coatings were viable. The highest silver content coatings tested (HAAg100 and HAAgFn100) resulted in a greater than 99% reduction in biofilm and planktonic bacterial numbers compared to HA and HAFn controls. Although HAAg100 had greater antibacterial activity than HAAgFn100, the findings of this study indicate that fibroblasts would win the race for the surface against S aureus on both HAAg100 and HAAgFn100 after serum-preconditioning.

  9. Graphene oxide decorated with silver nanoparticles as a coating on a stainless-steel fiber for solid-phase microextraction.

    Science.gov (United States)

    Wang, Licheng; Hou, Xiudan; Li, Jubai; Liu, Shujuan; Guo, Yong

    2015-07-01

    A novel graphene oxide decorated with silver nanoparticles coating on a stainless-steel fiber for solid-phase microextraction was prepared. Scanning electron microscopy and X-ray photoelectron spectroscopy were used to characterize the coating surface and showed that silver nanoparticles were dispersed on the wrinkled graphene oxide surface. Coupled to gas chromatography with flame ionization detection, the extraction abilities of the fiber for polycyclic aromatic hydrocarbons were examined in the headspace solid-phase microextraction mode. The extraction parameters including adsorption time, adsorption temperature, salt concentration, desorption time and desorption temperature were investigated. Under the optimized condition, wide linearity with low limits of detection from 2 to 10 ng/L was obtained. The relative standard deviations for single-fiber repeatability and fiber-to-fiber reproducibility were less than 10.6 and 17.5%, respectively. The enrichment factors were from 1712.5 to 4503.7, showing the fiber has good extraction abilities. Moreover, the fiber exhibited a good stability and could be reused for more than 120 times. The established method was also applied for determination of polycyclic aromatic hydrocarbons in two real water samples and the recoveries of analytes ranged from 84.4-116.3% with relative standard deviations less than 16.2%.

  10. Beneficial silver: antibacterial nanocomposite Ag-DLC coating to reduce osteolysis of orthopaedic implants

    Energy Technology Data Exchange (ETDEWEB)

    Endrino, J L; Sanchez-Lopez, J C; Galindo, R Escobar; Horwat, D; Anders, A, E-mail: jlendrino@icmm.csic.es

    2010-11-01

    Silver-containing diamond-like-carbon (DLC) is a promising material for biomedical implants due to its excellent combination of antibacterial and mechanical properties. In this work, a dual-cathode pulsed filtered cathodic arc source containing silver and graphite rods was employed in order to obtain DLC samples with various silver contents. Chemical composition of the samples was analyzed by acquiring their compositional depth-profiles using radio-frequency Glow Discharge Optical Emission Spectroscopy (rf-GDOES), while the microstructural properties were analyzed by X-ray diffraction and Raman spectroscopy. Tribological studies carried out against UHMWPE balls in fetal bovine serum indicate that the presence of silver in DLC could be beneficial to reduce the wear of the polymeric surfaces.

  11. Carbon nanotubes with silver nanoparticle decoration and conductive polymer coating for improving the electrical conductivity of polycarbonate composites

    KAUST Repository

    Patole, Archana S.

    2015-01-01

    We proposed a strategy to enhance the conductivity of polycarbonate by using three-phase hybrid metallic/non-metallic fillers. Ethylene diamine (EDA) functionalized multiwalled carbon nanotubes (MWCNT-EDA) are first decorated with silver nanoparticles. These Ag/ MWCNT-EDA fillers are then coated with a conductive layer of ethylene glycol treated PEDOT: PSS (poly [3,4-ethylenedioxythiophene]: poly [styrenesulfonate]) (EP). In such an approach, the MWCNT backbone is covered by a highly conductive coating made of Ag nanoparticles surrounded by EP. To understand how Ag and EP form a highly conductive coating, the effect of different wt% of Ag nanoparticles on EP was studied. Ag nanoparticles around the size of 128 ± 28 nmeffectively lowered the volume resistivity of bulk EP, resulting in a highly conducting Ag/EP blend. We found that in the final Ag/MWCNT-EDA/EP assembly, the EP coating enhances the electrical conductivity in two ways: (1) it is an efficient dispersing agent that helps in achieving a uniform dispersion of the Ag/MWCNT-EDA and (2) it acts as a conductive bridge between particles (Ag and MWCNT-EDA), reducing the particle to particle resistivity. When inserted into polycarbonate, this three-phase blend successfully reduced the volume resistivity of the polymer by two orders of magnitude compared with previous approaches.

  12. Cost-Effective Filter Materials Coated with Silver Nanoparticles for the Removal of Pathogenic Bacteria in Groundwater

    Science.gov (United States)

    Mpenyana-Monyatsi, Lizzy; Mthombeni, Nomcebo H.; Onyango, Maurice S.; Momba, Maggy N. B.

    2012-01-01

    The contamination of groundwater sources by pathogenic bacteria poses a public health concern to communities who depend totally on this water supply. In the present study, potentially low-cost filter materials coated with silver nanoparticles were developed for the disinfection of groundwater. Silver nanoparticles were deposited on zeolite, sand, fibreglass, anion and cation resin substrates in various concentrations (0.01 mM, 0.03 mM, 0.05 mM and 0.1 mM) of AgNO3. These substrates were characterised by SEM, EDS, TEM, particle size distribution and XRD analyses. In the first phase, the five substrates coated with various concentrations of AgNO3 were tested against E. coli spiked in synthetic water to determine the best loading concentration that could remove pathogenic bacteria completely from test water. The results revealed that all filters were able to decrease the concentration of E. coli from synthetic water, with a higher removal efficiency achieved at 0.1 mM (21–100%) and a lower efficiency at 0.01 mM (7–50%) concentrations. The cation resin-silver nanoparticle filter was found to remove this pathogenic bacterium at the highest rate, namely 100%. In the second phase, only the best performing concentration of 0.1 mM was considered and tested against presumptive E. coli, S. typhimurium, S. dysenteriae and V. cholerae from groundwater. The results revealed the highest bacteria removal efficiency by the Ag/cation resin filter with complete (100%) removal of all targeted bacteria and the lowest by the Ag/zeolite filter with an 8% to 67% removal rate. This study therefore suggests that the filter system with Ag/cation resin substrate can be used as a potential alternative cost-effective filter for the disinfection of groundwater and production of safe drinking water. PMID:22470290

  13. Bone loss at implant with titanium abutments coated by soda lime glass containing silver nanoparticles: a histological study in the dog.

    Science.gov (United States)

    Martinez, Arturo; Guitián, Francisco; López-Píriz, Roberto; Bartolomé, José F; Cabal, Belén; Esteban-Tejeda, Leticia; Torrecillas, Ramón; Moya, José S

    2014-01-01

    The aim of the present study was to evaluate bone loss at implants connected to abutments coated with a soda-lime glass containing silver nanoparticles, subjected to experimental peri-implantitis. Also the aging and erosion of the coating in mouth was studied. Five beagle dogs were used in the experiments. Three implants were placed in each mandible quadrant: in 2 of them, Glass/n-Ag coated abutments were connected to implant platform, 1 was covered with a Ti-mechanized abutment. Experimental peri-implantitis was induced in all implants after the submarginal placement of cotton ligatures, and three months after animals were euthanatized. Thickness and morphology of coating was studied in abutment cross-sections by SEM. Histology and histo-morphometric studies were carried on in undecalfied ground slides. After the induced peri-implantitis: 1.The abutment coating shown losing of thickness and cracking. 2. The histometry showed a significant less bone loss in the implants with glass/n-Ag coated abutments. A more symmetric cone of bone resorption was observed in the coated group. There were no significant differences in the peri-implantitis histological characteristics between both groups of implants. Within the limits of this in-vivo study, it could be affirmed that abutments coated with biocide soda-lime-glass-silver nanoparticles can reduce bone loss in experimental peri-implantitis. This achievement makes this coating a suggestive material to control peri-implantitis development and progression.

  14. Bone loss at implant with titanium abutments coated by soda lime glass containing silver nanoparticles: a histological study in the dog.

    Directory of Open Access Journals (Sweden)

    Arturo Martinez

    Full Text Available The aim of the present study was to evaluate bone loss at implants connected to abutments coated with a soda-lime glass containing silver nanoparticles, subjected to experimental peri-implantitis. Also the aging and erosion of the coating in mouth was studied. Five beagle dogs were used in the experiments. Three implants were placed in each mandible quadrant: in 2 of them, Glass/n-Ag coated abutments were connected to implant platform, 1 was covered with a Ti-mechanized abutment. Experimental peri-implantitis was induced in all implants after the submarginal placement of cotton ligatures, and three months after animals were euthanatized. Thickness and morphology of coating was studied in abutment cross-sections by SEM. Histology and histo-morphometric studies were carried on in undecalfied ground slides. After the induced peri-implantitis: 1.The abutment coating shown losing of thickness and cracking. 2. The histometry showed a significant less bone loss in the implants with glass/n-Ag coated abutments. A more symmetric cone of bone resorption was observed in the coated group. There were no significant differences in the peri-implantitis histological characteristics between both groups of implants. Within the limits of this in-vivo study, it could be affirmed that abutments coated with biocide soda-lime-glass-silver nanoparticles can reduce bone loss in experimental peri-implantitis. This achievement makes this coating a suggestive material to control peri-implantitis development and progression.

  15. Synthesis of new antibacterial composite coating for titanium based on highly ordered nanoporous silica and silver nanoparticles.

    Science.gov (United States)

    Massa, Miguel A; Covarrubias, Cristian; Bittner, Mauricio; Fuentevilla, Ignacio Andrés; Capetillo, Pavel; Von Marttens, Alfredo; Carvajal, Juan Carlos

    2014-12-01

    Infection is the most common factor that leads to dental titanium implant failure. Antibacterial implant surfaces based on nano-scale modifications of the titanium appear as an attractive strategy for control of peri-implantitis. In the present work, the preparation and antibacterial properties of a novel composite coating for titanium based on nanoporous silica and silver nanoparticles are presented. Starch-capped silver nanoparticles (AgNPs) were synthesized and then incorporated into sol-gel based solution system. The AgNP-doped nanoporous silica coatings were prepared on titanium surface using a combined sol-gel and evaporation-induced self-assembly (EISA) method. The coating nanostructure was characterized by XRD, SEM-EDX, and HR-TEM. Antibacterial activity was evaluated against Aggregatibacter actinomycetemcomitans, a representative pathogen of dental peri-implantitis. Colony-forming units (CFUs) were counted within the biofilm and at the planktonic state. Biofilm development was quantified using crystal violet staining and viability of adherent bacteria was confirmed with the Live/Dead fluorescence assay. Silica-based composite coating containing AgNPs (AgNP/NSC) was prepared on titanium surface by direct incorporation of AgNP suspension into the sol-gel system. The self-assembly technique enabled the spontaneous formation of a highly ordered nanoporosity in the coating structure, which is a desired property for osseointegration aspects of titanium implant surface. AgNP/NSC coating produces a strong antibacterial effect on titanium surface by not only killing the adherent bacteria but also reducing the extent of biofilm formation. Biofilm survival is reduced by more than 70% on the AgNP/NSC-modified titanium surface, compared to the control. This antibacterial effect was verified for up to 7 days of incubation. The long-term antibacterial activity exhibited by the nanostructured AgNP/NSC-titanium surface against A. actinomycetemcomitans suggests that this

  16. A photochemical approach designed to improve the coating of nanoscale silver films onto food plastic wrappings intended to control bacterial hazards

    Energy Technology Data Exchange (ETDEWEB)

    Mustatea, Gabriel [University Politehnica of Bucharest, Faculty of Applied Chemistry and Materials Science (Romania); Vidal, Loïc [Institut de Sciences des Matériaux de Mulhouse, CNRS UMR 7361 (France); Calinescu, Ioan [University Politehnica of Bucharest, Faculty of Applied Chemistry and Materials Science (Romania); Dobre, Alina; Ionescu, Mariana [National Research and Development Institute for Food Bioresources – IBA Bucharest (Romania); Balan, Lavinia, E-mail: lavinia.balan@uha.fr [Institut de Sciences des Matériaux de Mulhouse, CNRS UMR 7361 (France)

    2015-01-15

    Plasmonic silver film was directly generated on a variety of substrates through a facile and environmentally friendly method, which involves a UV-photoreduction process without any reducing or stabilizing agent and requiring no thermal step. Top-coated films of unprotected silver nanoparticles (3–11 nm) were generated from hydroalcoholic AgNO{sub 3} solution and directly on glass substrates or food packaging plastic wraps, low density polyethylene film, and polyvinyl chloride. The natural antibacterial activity of the material was evaluated. The correlation between silver migration and antimicrobial activity of silver-functionalized substrates against pure strains of gram-negative bacteria (Escherichia coli) and gram-positive bacteria (Staphylococcus aureus) was demonstrated. By way of illustration, food plastic wraps top-coated in this way exhibited a high antibacterial activity. The metal nanoparticle film obtained in this way was characterized and the influence of several parameters (fluence, exposure, silver nitrate concentration, and nature of the free radicals generator) on their formation was studied. Moreover, by shaping the actinic beam with an appropriate device, it is very easy to pattern the brown yellow silver nanofilm or to print messages in plain text.

  17. Inhibitory effect on in vitro Streptococcus oralis biofilm of a soda-lime glass containing silver nanoparticles coating on titanium alloy.

    Directory of Open Access Journals (Sweden)

    Belén Cabal

    Full Text Available This paper reports the effect of soda-lime-glass-nAg coating on the viability of an in vitro biofilm of Streptococcus oralis. Three strains (ATCC 35037 and two clinical isolates from periodontitis patients were grown on coated with glass, glass containing silver nanoparticles, and uncoated titanium alloy disks. Two different methods were used to quantify biofilm formation abilities: crystal violet staining and determination of viable counts. The influence of the surface morphology on the cell attachment was studied. The surface morphology was characterized by scanning electron microscopy (SEM and using a profilometer. SEM was also used to study the formation and the development of biofilm on the coated and uncoated disks. At least a >99.7% inocula reduction of biofilm respect to titanium disks and also to glass coated disks was observed in the glass-nAg coated disks for all the studied strains. A quantitative evaluation of the release of silver was conducted in vitro to test whether and to what extend the biocidal agent (silver could leach from the coating. These findings suggest that the biofilm formation of S. oralis strains is highly inhibited by the glass-nAg and may be useful for materials which require durable antibacterial effect on their surfaces, as it is the case of dental implants.

  18. Inhibitory effect on in vitro Streptococcus oralis biofilm of a soda-lime glass containing silver nanoparticles coating on titanium alloy.

    Science.gov (United States)

    Cabal, Belén; Cafini, Fabio; Esteban-Tejeda, Leticia; Alou, Luís; Bartolomé, José F; Sevillano, David; López-Piriz, Roberto; Torrecillas, Ramón; Moya, José Serafín

    2012-01-01

    This paper reports the effect of soda-lime-glass-nAg coating on the viability of an in vitro biofilm of Streptococcus oralis. Three strains (ATCC 35037 and two clinical isolates from periodontitis patients) were grown on coated with glass, glass containing silver nanoparticles, and uncoated titanium alloy disks. Two different methods were used to quantify biofilm formation abilities: crystal violet staining and determination of viable counts. The influence of the surface morphology on the cell attachment was studied. The surface morphology was characterized by scanning electron microscopy (SEM) and using a profilometer. SEM was also used to study the formation and the development of biofilm on the coated and uncoated disks. At least a >99.7% inocula reduction of biofilm respect to titanium disks and also to glass coated disks was observed in the glass-nAg coated disks for all the studied strains. A quantitative evaluation of the release of silver was conducted in vitro to test whether and to what extend the biocidal agent (silver) could leach from the coating. These findings suggest that the biofilm formation of S. oralis strains is highly inhibited by the glass-nAg and may be useful for materials which require durable antibacterial effect on their surfaces, as it is the case of dental implants.

  19. Silsesquioxane-based hybrid nanocomposites with methacrylate units containing titania and/or silver nanoparticles as antibacterial/antifungal coatings for monumental stones

    Energy Technology Data Exchange (ETDEWEB)

    Aflori, Magdalena [“Petru Poni” Institute of Macromolecular Chemistry, 41A Grigore Ghica Voda Alley, 700487 Iasi (Romania); Simionescu, Bogdana [“Petru Poni” Institute of Macromolecular Chemistry, 41A Grigore Ghica Voda Alley, 700487 Iasi (Romania); “Costin D. Nenitescu” Centre of Organic Chemistry, 202B Splaiul Independentei, 7114 Bucharest (Romania); Bordianu, Irina-Elena; Sacarescu, Liviu; Varganici, Cristian-Dragos; Doroftei, Florica; Nicolescu, Alina [“Petru Poni” Institute of Macromolecular Chemistry, 41A Grigore Ghica Voda Alley, 700487 Iasi (Romania); Olaru, Mihaela, E-mail: olaruma@icmpp.ro [“Petru Poni” Institute of Macromolecular Chemistry, 41A Grigore Ghica Voda Alley, 700487 Iasi (Romania)

    2013-11-20

    Highlights: • Synthesis of nanocomposites with noble metals having high antibacterial efficiency. • Silver nanoparticles antibacterial activity for monumental stone conservation. • A high antibacterial activity while assuring good stone protection. -- Abstract: The present paper reports on the evaluation of two silsesquioxane-based hybrid nanocomposites with methacrylate units containing titania and/or silver nanoparticles aimed as antibacterial coatings for monumental stones. Sol–gel reaction of titanium isopropoxide and/or 3-(trimethoxysilyl)propyl methacrylate, in the presence of silver nitrate and a primary amine surfactant, yielded new types of hybrid nanocomposites with high antibacterial/antifungal efficacy. Different polymer behaviours regarding a frequently used monumental stone originating from Romania were evidenced through Fourier-transform infrared (FTIR) spectroscopy and powder X-ray diffraction (PXRD) technique. Conclusions regarding the stones acid-resistant character and lower influence of salt weathering on its durability, as well as a better protective coating containing titania units were revealed.

  20. Synthesis and characterization of silver colloidal nanoparticles with different coatings for SERS application

    Energy Technology Data Exchange (ETDEWEB)

    Mikac, L.; Ivanda, M., E-mail: ivanda@irb.hr [Ruđer Bošković Institute, Laboratory for Molecular Physics (Croatia); Gotić, M. [Ruđer Bošković Institute, Laboratory for Synthesis of New Materials (Croatia); Mihelj, T. [Ruđer Bošković Institute, Laboratory for Synthesis and Processes of Self-assembling of Organic Molecules (Croatia); Horvat, L. [Ruđer Bošković Institute, Laboratory for Electron Microscopy (Croatia)

    2014-12-15

    Silver colloids were produced by chemical reduction of silver salt (silver nitrate, AgNO{sub 3}) solution. As reducing agents, trisodium citrate, sodium borohydride, ascorbic acid, polyvinylpyrrolidone, and glucose were used. The colloids were characterized by UV–Vis, DLS, zeta potential measurements, and SEM. The colloids were stabilized with negative groups or large molecules attached to their surface. The surface-enhanced Raman scattering (SERS) effect of stabilized nanoparticles was measured by using pyridine and rhodamine 6G molecules as analytes and NaNO{sub 3}, KCl, and KBr at different concentrations as aggregating agents. The best Raman signal enhancement was achieved using silver nanoparticles of 40 nm size reduced and stabilized with citrate. The SERS signal of analyte molecules was further enhanced with the addition of sodium borohydride as an alternative aggregating agent. The borohydride had the strongest impact on the SERS effect of the colloid consistent of large (0.5 µm) silver nanoparticles stabilized with aminodextran. The mixture colloid-borohydride-pyridine was stable for hours. The mechanism of borohydride in the colloids is discussed.

  1. Surface stabilized GMR nanorods of silver coated CrO{sub 2} synthesized via a polymer complex at ambient pressure

    Energy Technology Data Exchange (ETDEWEB)

    Biswas, S., E-mail: drsomnathbiswas@gmail.com [The LNM Institute of Information Technology, Jaipur-302031 (India); Singh, G.P. [Centre for Nanotechnology, Central University of Jharkhand, Ranchi-835205 (India); Ram, S. [Materials Science Centre, Indian Institute of Technology, Kharagpur-721302 (India); Fecht, H.-J. [Insitut für Micro-und Nanomaterialien, Universität Ulm, Albert Einstein Allee-47, Ulm, D-89081, and Forschungszentrum Karlsruhe, Institute of Nanotechnology, Karlsruhe, D-76021 (Germany)

    2013-08-15

    Stable anisotropic nanorods of surface modified CrO{sub 2} (∼18 nm diameter) with a correlated diamagnetic layer (2–3 nm thickness) of silver efficiently tailors useful magnetic and magnetoresistance (MR) properties. Essentially, it involves a core-shell structure that is developed by displacing part of Cr{sup 4+} ions by Ag atoms on the CrO{sub 2} surface (topotactic surface layer) via an etching reaction of a CrO{sub 2}-polymer complex with Ag{sup +} ions in hot water followed by heating the dried sample at 300–400 °C in air. The stable Ag-layer so obtained in the form of a shell protects CrO{sub 2} such that it no longer converts to Cr{sub 2}O{sub 3} in ambient pressure during the processing. X-ray diffractogram of the Rutile type tetragonal CrO{sub 2} structure (lattice parameters a=0.4429 nm and c=0.2950 nm) includes weak peaks of a minority phase of an fcc-Ag (a=0.4086 nm). The silver surface layer, which manifests itself in a doublet of the 3d{sub 5/2} and 3d{sub 3/2} X-ray photoelectron bands of binding energies 368.46 eV and 374.48 eV, respectively, suppresses almost all Cr bands to appear in a measurable intensity. The sample exhibits a distinctly enhanced MR-value, e.g., (−) 7.6% at 77 K, than reported values in compacted CrO{sub 2} powders or composites. Such a large MR-value in the Coulomb blockade regime (<100 K) arises not only due to the suppressed spin flipping at low temperature but also from a spin dependent co-tunneling through an interlinked structure of silver and silver coated CrO{sub 2} nanorods. - Highlights: • Synthesis and structural studies of a novel GMR material of Ag coated CrO{sub 2}. • Tailoring useful GMR property in CrO{sub 2} nanorods of controlled shape and anisotropy. • Enhanced GMR is explained in correlation to the surface structure of CrO{sub 2} nanorods.

  2. Molecular structure, optical, electrical and sensing properties of PANI-based coatings with silver nanoparticles deposited from the active gas phase

    Energy Technology Data Exchange (ETDEWEB)

    Ragachev, A.A., E-mail: rogachev78@mail.ru [International Chinese-Belorussian Scientific Laboratory on Vacuum-Plasma Technology, College of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); National Research Tomsk Polytechnic University, 30, Lenin Avenue, Tomsk 634050 (Russian Federation); Yarmolenko, M.A. [International Chinese-Belorussian Scientific Laboratory on Vacuum-Plasma Technology, College of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); National Research Tomsk Polytechnic University, 30, Lenin Avenue, Tomsk 634050 (Russian Federation); Xiaohong, Jiang [International Chinese-Belorussian Scientific Laboratory on Vacuum-Plasma Technology, College of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Shen, Ruiqi [Key Lab of Soft Chemistry and Functional Materials of Ministry of Education, Nanjing University of Science and Technology, Nanjing 210094 (China); Luchnikov, P.A. [National Research Tomsk Polytechnic University, 30, Lenin Avenue, Tomsk 634050 (Russian Federation); Rogachev, A.V. [Francisk Skorina Gomel State University, 104, Sovetskaya Street, Gomel 246019 (Belarus)

    2015-10-01

    Highlights: • PANI-based coatings were deposited by plasma chemical solvent-free method. • PANI + AgCl coating has a partially doped structure with low variation in size of oxidized and reduced PANI units. • The increasing of the sensing performance of this coating was established at the low frequency region of impedance spectra. - Abstract: The plasma chemical solvent-free method of doped and nanocomposite polyaniline-based (PANI-based) conductive coatings deposition was elaborated. Molecular structure, morphology, optical, electrical and sensing properties of PANI-based coating were investigated by Fourier transform infrared, UV–vis, impedance spectroscopy methods and transmittance electron microscopy. The synthesized PANI-based coatings containing silver nanoparticles have a partially doped structure with low variation in size of oxidized and reduced PANI units. The nanocomposite PANI-based coatings were deposited onto interdigital capacitor for ammonia gas sensing applications. The increasing of the sensing performance of the PANI-based coatings with silver nanoparticles was established in particular at the low frequency region of impedance spectra. The high sensitivity and linearity of this sensor response were examined at a direct and alternating voltage with ammonia concentrations up to 10 ppm.

  3. A prospective interventional study to examine the effect of a silver alloy and hydrogel-coated catheter on the incidence of catheter-associated urinary tract infection.

    Science.gov (United States)

    Chung, P Hy; Wong, C Wy; Lai, C Kc; Siu, H K; Tsang, D Nc; Yeung, K Y; Ip, D Km; Tam, P Kh

    2017-06-01

    Catheter-associated urinary tract infection is a major hospital-acquired infection. This study aimed to analyse the effect of a silver alloy and hydrogel-coated catheter on the occurrence of catheter-associated urinary tract infection. This was a 1-year prospective study conducted at a single centre in Hong Kong. Adult patients with an indwelling urinary catheter for longer than 24 hours were recruited. The incidence of catheter-associated urinary tract infection in patients with a conventional latex Foley catheter without hydrogel was compared with that in patients with a silver alloy and hydrogel-coated catheter. The most recent definition of urinary tract infection was based on the latest surveillance definition of the National Healthcare Safety Network managed by Centers for Disease Control and Prevention. A total of 306 patients were recruited with a similar ratio between males and females. The mean (standard deviation) age was 81.1 (10.5) years. The total numbers of catheter-days were 4352 and 7474 in the silver-coated and conventional groups, respectively. The incidences of catheter-associated urinary tract infection per 1000 catheter-days were 6.4 and 9.4, respectively (P=0.095). There was a 31% reduction in the incidence of catheter-associated urinary tract infection per 1000 catheter-days in the silver-coated group. Escherichia coli was the most commonly involved pathogen (36.7%) of all cases. Subgroup analysis revealed that the protective effect of silver-coated catheter was more pronounced in long-term users as well as female patients with a respective 48% (P=0.027) and 42% (P=0.108) reduction in incidence of catheter-associated urinary tract infection. The mean catheterisation time per person was the longest in patients using a silver-coated catheter (17.0 days) compared with those using a conventional (10.8 days) or both types of catheter (13.6 days) [P=0.01]. Silver alloy and hydrogel-coated catheters appear to be effective in preventing catheter

  4. Fabrication and characterization of silver- and copper-coated Nylon 6 forcespun nanofibers by thermal evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Mihut, Dorina M., E-mail: dorinamm@yahoo.com; Lozano, Karen [Department of Mechanical Engineering, The University of Texas Pan American, 1201 W University Drive, Edinburg, Texas 78539 (United States); Foltz, Heinrich [Department of Electrical Engineering, The University of Texas Pan American, 1201 W University Drive, Edinburg, Texas 78539 (United States)

    2014-11-01

    Silver and copper nanoparticles were deposited as thin films onto substrates consisting of Nylon 6 nanofibers manufactured using forcespinning{sup ®} equipment. Different rotational speeds were used to obtain continuous nanofibers of various diameters arranged as nonwoven mats. The Nylon 6 nanofibers were collected as successive layers on frames, and a high-vacuum thermal evaporation method was used to deposit the silver and copper thin films on the nanofibers. The structures were investigated using scanning electron microscopy–scanning transmission electron microscopy, atomic force microscopy, x-ray diffraction, and electrical resistance measurements. The results indicate that evaporated silver and copper nanoparticles were successfully deposited on Nylon 6 nanofibers as thin films that adhered well to the polymer substrate while the native morphology of the nanofibers were preserved, and electrically conductive nanostructures were achieved.

  5. PVP-coated, negatively charged silver nanoparticles: A multi-center study of their physicochemical characteristics, cell culture and in vivo experiments

    Directory of Open Access Journals (Sweden)

    Sebastian Ahlberg

    2014-11-01

    Full Text Available PVP-capped silver nanoparticles with a diameter of the metallic core of 70 nm, a hydrodynamic diameter of 120 nm and a zeta potential of −20 mV were prepared and investigated with regard to their biological activity. This review summarizes the physicochemical properties (dissolution, protein adsorption, dispersability of these nanoparticles and the cellular consequences of the exposure of a broad range of biological test systems to this defined type of silver nanoparticles. Silver nanoparticles dissolve in water in the presence of oxygen. In addition, in biological media (i.e., in the presence of proteins the surface of silver nanoparticles is rapidly coated by a protein corona that influences their physicochemical and biological properties including cellular uptake. Silver nanoparticles are taken up by cell-type specific endocytosis pathways as demonstrated for hMSC, primary T-cells, primary monocytes, and astrocytes. A visualization of particles inside cells is possible by X-ray microscopy, fluorescence microscopy, and combined FIB/SEM analysis. By staining organelles, their localization inside the cell can be additionally determined. While primary brain astrocytes are shown to be fairly tolerant toward silver nanoparticles, silver nanoparticles induce the formation of DNA double-strand-breaks (DSB and lead to chromosomal aberrations and sister-chromatid exchanges in Chinese hamster fibroblast cell lines (CHO9, K1, V79B. An exposure of rats to silver nanoparticles in vivo induced a moderate pulmonary toxicity, however, only at rather high concentrations. The same was found in precision-cut lung slices of rats in which silver nanoparticles remained mainly at the tissue surface. In a human 3D triple-cell culture model consisting of three cell types (alveolar epithelial cells, macrophages, and dendritic cells, adverse effects were also only found at high silver concentrations. The silver ions that are released from silver nanoparticles may be

  6. Gas Sorption, Diffusion, and Permeation in Nafion

    KAUST Repository

    Mukaddam, Mohsin Ahmed

    2015-12-22

    The gas permeability of dry Nafion films was determined at 2 atm and 35 °C for He, H2, N2, O2, CO2, CH4, C2H6, and C3H8. In addition, gas sorption isotherms were determined by gravimetric and barometric techniques as a function of pressure up to 20 atm. Nafion exhibited linear sorption uptake for low-solubility gases, following Henry’s law, and convex behavior for highly sorbing condensable gases, indicating rubber-like behavior at 35 °C. XRD results demonstrated that Nafion contains bimodal amorphous chain domains with average d-spacing values of 2.3 and 5.3 Å. Only helium and hydrogen showed relatively high gas permeability of 37 and 7 barrers, respectively; all other gases exhibited low permeability that decreased significantly as penetrant size increased. Dry Nafion was characterized by extraordinarily high selectivities: He/H2 = 5.2, He/CH4 = 445, He/C2H6 = 1275, He/C3H8 = 7400, CO2/CH4 = 28, CO2/C2H6 = 79, CO2/C3H8 = 460, H2/CH4 = 84, H2/C2H6 = 241, and H2/C3H8 = 1400. These high selectivities could make Nafion a potential candidate membrane material for dry feeds for helium recovery and carbon dioxide separation from natural gas and removal of higher hydrocarbons from hydrogen-containing refinery gases.

  7. Vegetable-Oil-Based Hyperbranched Polyester-Styrene Copolymer Containing Silver Nanoparticle as Antimicrobial and Corrosion-Resistant Coating Materials

    Directory of Open Access Journals (Sweden)

    Manawwer Alam

    2013-01-01

    Full Text Available Pongamia oil (PO was converted to Pongamia oil hydroxyl (POH via epoxidation process. The esterification of POH with linolenic acid was carried out to form hyperbranched polyester (HBPE, and further styrenation was performed at the conjugated double bond in the chain of linolenic acid. After styrenation, silver nanoparticle was added in different weight percentages (0.1–0.4 wt%. The structural elucidation of POH, HBPE, and HBPE-St was carried out by FT-IR, 1H-NMR, and 13C-NMR spectroscopic techniques. Physicochemical and physicomechanical analyses were performed by standard method. Thermal behavior of the HBPE-St was analyzed by using thermogravimetric analysis (TGA and differential scanning calorimetry (DSC. The coatings of HBPE-St were prepared on mild steel strips. The anticorrosive behavior of HBPE-St resin-based coatings in acid, saline, and tap water was evaluated, and the molecular weight of HBPE-St was determined by gel permeation chromatography (GPC. The antibacterial activities of the HBPE-St copolymers were tested in vitro against bacteria and fungi by disc diffusion method. The HBPE-St copolymers exhibited good antibacterial activities and can be used as antimicrobial and corrosion-resistant coating materials.

  8. Surface enhanced Raman spectroscopy on silver-nanoparticle-coated carbon-nanotube networks fabricated by electrophoretic deposition

    Science.gov (United States)

    Sarkar, Anirban; Wang, Hao; Daniels-Race, Theda

    2014-03-01

    In this study, the efficiency of silver nanoparticle (AgNP) decorated carbon nanotube (CNT) based porous substrates has been investigated for surface-enhanced Raman spectroscopy (SERS) applications. The fabrication of uniform thin coatings of carbon nanotubes is accomplished by Electrophoretic Deposition (EPD) on organosilane functionalized silicon substrates. The deposition process exemplifies a fast, reproducible and single-step room temperature coating strategy to fabricate horizontally aligned porous CNT network. Surfactant stabilized AgNPs were deposited on the CNT networks by immersion coating. The acquired Raman spectra of Rhodamine6G (R6G) analyte examined on the fabricated Ag-CNT-Si substrates exhibited enhanced signal intensity values when compared to SERS-active planar AgNP-Si substrates. An overall enhancement factor of ˜109 was achieved for the tested analyte which enables pushing the limit of detection to 1 × 10-12 M (1 pM). The enhancement can be attributed to the large surface area offered by the AgNP-CNT porous network, which is expected to increase the number of effective "hot spots" for the SERS effect.

  9. The effect of heat treatment on the microstructure and diffusion of silver in pyrolytic carbon coatings

    OpenAIRE

    CANCINO TREJOA F.; SÁENZ PADILLA M.; LOPEZ HONORATO Eddie; CARVAJAL NUNEZ URSULA; BOSHOVEN Jacobus; Somers, Joseph

    2016-01-01

    It is well accepted that TRISO (tristructural isotropic) coated nuclear fuel particles are capable of retaining fission products up to 1600 ºC, however above this temperature fission products can diffuse through the pyrolytic carbon and silicon carbide coatings that act as the containment barriers in this fuel. Despite decades of research and development, little is known on the origin of this fuel temperature limit. Since pyrolytic carbon (PyC) coatings are an integral part of the safety of ...

  10. Enhanced electrical conductivity and hardness of silver-nickel composites by silver-coated multi-walled carbon nanotubes.

    Science.gov (United States)

    Lee, Dongmok; Sim, Jeonghyun; Kim, Wonyoung; Moon, Chuldong; Cho, Wookdong; Baik, Seunghyun

    2015-07-24

    We investigated electrical conductivity and Vickers hardness of Ag- and Ni-based composites prepared by powder metallurgy involving spark plasma sintering. The starting composition was Ag:Ni = 61:39 vol%, which provided an electrical conductivity of 3.30 × 10(5) S cm(-1) and a hardness of 1.27 GPa. The addition of bare multi-walled carbon nanotubes (MWNTs, 1.45 vol%) increased hardness (1.31 GPa) but decreased electrical conductivity (2.99 × 10(5) S cm(-1)) and carrier mobility (11 cm(2) V(-1) s(-1)) due to the formation of Ni3C in the interface between the MWNTs and Ni during spark plasma sintering. The formation of Ni3C was prevented by coating the surface of the nanotubes with Ag (nAgMWNTs), concomitantly increasing electrical conductivity (3.43 × 10(5) S cm(-1)) and hardness (1.37 GPa) of the sintered specimen (Ag:Ni:nAgMWNTs = 59.55:39:1.45 vol%). The electrical contact switching time (133 357) was also increased by 30%, demonstrating excellent feasibility as electrical contact materials for electric power industries.

  11. Manipulated localized surface plasmon resonances in silver nanoshells coated with a spherical anisotropic layer

    Institute of Scientific and Technical Information of China (English)

    Jiang Shu-Min; Wu Da-Jian; Cheng Ying; Liu Xiao-Jun

    2012-01-01

    The influences of the anisotropy of the outer spherically anisotropic (SA) layer on the far-field spectra and near-field enhancements of the silver nanoshells are investigated by using a modified Mie scattering theory.It is found that with the increase of the anisotropic value of the SA layer,the dipole resonance wavelength of the silver nanoshell first increases and then decreases,while the local field factor (LFF) reduces.With the decrease of SA layer thickness,the dipole wavelength of the silver nanoshell shows a distinct blue-shift.When the SA layer becomes very thin,the modulations of the anisotropy of the SA layer on the plasmon resonance energy and the near-field enhancement are weakened.We further find that the smaller anisotropic value of the SA layer is helpful for obtaining the larger near-field enhancement in the Ag nanoshell.The geometric average of the dielectric components of the SA layer has a stronger effect on the plasmon resonance energy of the silver nanoshell than on the near-field enhancement.

  12. Ultra-Thin Films of Poly(acrylic acid/Silver Nanocomposite Coatings for Antimicrobial Applications

    Directory of Open Access Journals (Sweden)

    Alaa Fahmy

    2016-01-01

    Full Text Available In this work not only colloids of poly(acrylic acid (PAA embedded with silver nanoparticles (Ag-NPs but thin films (10 nm also were deposited using electrospray deposition technique (ESD. A mixture of sodium borohydride (NaBH4 and ascorbic acid (AA were utilized to reduce the silver ions to generate Ag-NPs in the PAA matrix. Moreover, sodium tricitrate was used to stabilize the prepared colloids. The obtained colloids and films were characterized using UV-visible, transmission electron microscopy (TEM. UV-Vis results reveal that an absorption peak at 425 nm was observed in presence of PAA-AgNO3-AA-citrate-NaBH4. This peak is attributed to the well-known surface plasmon resonance of the silver bound in Ag-NPs, while the reduction was rendering and/or inhibiting in absence of the AA and citrate. FTIR spectroscopy was used to study the mechanism of the reaction process of silver nitrate with PAA. TEM images showed the well dispersion of Ag-NPs in the PAA matrix with average particle size of 8 nm. The antimicrobial studies showed that the Ag-NPs embedded in the PAA matrix have proven to have a significant antimicrobial activity against E. coli, B. subtilis, and C. albicans.

  13. Comparison of Some Mechanical and Physical Methods for Measurement of Residual Stresses in Brush-Plated Nickel Hardened Gold and Silver Coatings

    Directory of Open Access Journals (Sweden)

    Harri LILLE

    2016-05-01

    Full Text Available Hard gold and silver are applied in coating owing to their high hardness, good wear and corrosion resistance for engineering application (e.g. on generators slip rings, sliding contacts and small machine parts and are typically plated on copper (mostly, brass and bronze. The studied nickel-hardened gold and silver coatings were brush plated on open thin-walled copper ring substrates. Residual stresses in the coatings were calculated from the curvature changes of the substrates. Biaxial intrinsic residual stresses were also determined by nanoindentation testing and by the X-ray technique. The values of the residual stresses represented tensile stresses and when determined by the techniques used they were comparable within a maximum limit of measurement uncertainty. These stresses relax; the dependence of relaxation time was approximated by a linear-fractional function.DOI: http://dx.doi.org/10.5755/j01.ms.22.1.7439

  14. Citrate-coated silver nanoparticles interactions with effluent organic matter: influence of capping agent and solution conditions

    KAUST Repository

    Gutierrez, Leonardo

    2015-07-31

    Fate and transport studies of silver nanoparticles (AgNPs) discharged from urban wastewaters containing effluent organic matter (EfOM) into natural waters represent a key knowledge gap. In this study, EfOM interfacial interactions with AgNPs and their aggregation kinetics were investigated by atomic force microscopy (AFM) and time-resolved dynamic light scattering (TR-DLS), respectively. Two well-characterized EfOM isolates, i.e., wastewater humic (WW humic) and wastewater colloids (WW colloids, a complex mixture of polysaccharides-proteins-lipids), and a River humic isolate of different characteristics were selected. Citrate-coated AgNPs were selected as representative capped-AgNPs. Citrate-coated AgNPs showed a considerable stability in Na+ solutions. However, Ca2+ ions induced aggregation by cation bridging between carboxyl groups on citrate. Although the presence of River humic increased the stability of citrate-coated AgNPs in Na+ solutions due to electrosteric effects, they aggregated in WW humic-containing solutions, indicating the importance of humics characteristics during interactions. Ca2+ ions increased citrate-coated AgNPs aggregation rates in both humic solutions, suggesting cation bridging between carboxyl groups on their structures as a dominant interacting mechanism. Aggregation of citrate-coated AgNPs in WW colloids solutions was significantly faster than those in both humic solutions. Control experiments in urea solution indicated hydrogen bonding as the main interacting mechanism. During AFM experiments, citrate-coated AgNPs showed higher adhesion to WW humic than to River humic, evidencing a consistency between TR-DLS and AFM results. Ca2+ ions increased citrate-coated AgNPs adhesion to both humic isolates. Interestingly, strong WW colloids interactions with citrate caused AFM probe contamination (nanoparticles adsorption) even at low Na+ concentrations, indicating the impact of hydrogen bonding on adhesion. These results suggest the importance

  15. Highly stable polymer coated nano-clustered silver plates: a multimodal optical contrast agent for biomedical imaging.

    Science.gov (United States)

    Ray, Aniruddha; Mukundan, Ananya; Xie, Zhixing; Karamchand, Leshern; Wang, Xueding; Kopelman, Raoul

    2014-11-07

    Here, we present a new optical contrast agent based on silver nanoplate clusters embedded inside of a polymer nano matrix. Unlike nanosphere clusters, which have been well studied, nanoplate clusters have unique properties due to the different possible orientations of interaction between the individual plates, resulting in a significant broadening of the absorption spectra. These nanoclusters were immobilized inside of a polymer cladding so as to maintain their stability and optical properties under in vivo conditions. The polymer-coated silver nanoplate clusters show a lower toxicity compared to the uncoated nanoparticles. At high nanoparticle concentrations, cell death occurs mostly due to apoptosis. These nanoparticles were used for targeted fluorescence imaging in a rat glioma cell line by incorporating a fluorescent dye into the matrix, followed by conjugation of a tumor targeting an F3 peptide. We further used these nanoparticles as photoacoustic contrast agents in vivo to enhance the contrast of the vasculature structures in a rat ear model. We observed a contrast enhancement of over 90% following the nanoparticle injection. It is also shown that these NPs can serve as efficient contrast agents, with specific targeting abilities for broadband multimodal imaging that are usable for diagnostic applications and that extend into use as therapeutic agents as well.

  16. Highly stable polymer coated nano-clustered silver plates: a multimodal optical contrast agent for biomedical imaging

    Science.gov (United States)

    Ray, Aniruddha; Mukundan, Ananya; Xie, Zhixing; Karamchand, Leshern; Wang, Xueding; Kopelman, Raoul

    2014-11-01

    Here, we present a new optical contrast agent based on silver nanoplate clusters embedded inside of a polymer nano matrix. Unlike nanosphere clusters, which have been well studied, nanoplate clusters have unique properties due to the different possible orientations of interaction between the individual plates, resulting in a significant broadening of the absorption spectra. These nanoclusters were immobilized inside of a polymer cladding so as to maintain their stability and optical properties under in vivo conditions. The polymer-coated silver nanoplate clusters show a lower toxicity compared to the uncoated nanoparticles. At high nanoparticle concentrations, cell death occurs mostly due to apoptosis. These nanoparticles were used for targeted fluorescence imaging in a rat glioma cell line by incorporating a fluorescent dye into the matrix, followed by conjugation of a tumor targeting an F3 peptide. We further used these nanoparticles as photoacoustic contrast agents in vivo to enhance the contrast of the vasculature structures in a rat ear model. We observed a contrast enhancement of over 90% following the nanoparticle injection. It is also shown that these NPs can serve as efficient contrast agents, with specific targeting abilities for broadband multimodal imaging that are usable for diagnostic applications and that extend into use as therapeutic agents as well.

  17. Influences of the coating on silver nanoparticle toxicity in a chronic test with Daphnia magna

    DEFF Research Database (Denmark)

    Sakka, Y.; Mackevica, Aiga; Skjolding, Lars Michael

    2015-01-01

    coated AgNP in a chronic Daphnia test. One type of AgNP was coated with citrate (cAgNP), the other AgNP were generally uncoated (pAgNP; p= pure), but sterically stabilized by an organic dispersant. Particles with a similar shape and diameter were chosen. The focus of the study was to relate observed...

  18. Green synthesis of Kocuran-functionalized silver glyconanoparticles for use as antibiofilm coatings on silicone urethral catheters

    Science.gov (United States)

    Ganesh Kumar, C.; Sujitha, Pombala

    2014-08-01

    Microbial infections due to biofilm formation on medical implants are serious complications arising after surgery which can be prevented by using antimicrobial coatings on biomaterial surfaces. We developed a simple, rapid and green chemistry approach for synthesis of silver glyconanoparticles (AgNPs) using Kocuran, an exopolysaccharide produced by Kocuria rosea strain BS-1. Kocuran-capped AgNPs exhibited a characteristic surface plasmon resonance (SPR) peak around 435 nm. They were mono-dispersed, spherical with an average particle size of 12 nm. XRD and SAED studies suggested that AgNPs were crystalline in nature. AgNPs had a zeta potential of -33.9 mV and were anionic charged. They showed colloidal stability at different pH (6 to 10), temperatures (30 °C to 100 °C), in NaCl, NaNO3 and BSA solutions. Kocuran-capped AgNPs exhibited effective antimicrobial activity against Staphylococcus aureus and Escherichia coli and cell death was mainly due to hydroxyl radical induction and depletion of NADH. They also inhibited the biofilm development by S. aureus and E. coli and confocal scanning laser microscopic images revealed the damage of intact cell architecture. In vitro evaluation of Kocuran-capped silver glyconanoparticles on human gingival fibroblasts demonstrated good cell proliferation as compared to commercial AgNPs suggesting that they are biocompatible and non-toxic in nature. This is a first report on Kocuran-functionalized AgNPs exhibiting potential antibacterial and antiadhesive properties for use as antimicrobial coatings against bacterial adhesion and biofilm formation on silicone urethral catheters.

  19. Inflammatory responses of a human keratinocyte cell line to 10 nm citrate- and PEG-coated silver nanoparticles

    Science.gov (United States)

    Bastos, V.; Brown, D.; Johnston, H.; Daniel-da-Silva, A. L.; Duarte, I. F.; Santos, C.; Oliveira, H.

    2016-07-01

    Silver nanoparticles (AgNPs) are among the most commonly used engineered NPs and various commercially available products are designed to come in direct contact with the skin (wound dressings, textiles, creams, among others). Currently, there is limited understanding of the influence of coatings on the toxicity of AgNPs and in particular their ability to impact on AgNP's mediated inflammatory responses. As AgNPs are often stabilized by different coatings, including citrate and polyethyleneglycol (PEG), in this study we investigate the influence of citrate (Cit10) or PEG (PEG10) coatings to 10 nm AgNP on skin, using human HaCaT keratinocytes. AgNPs cytotoxicity and inflammatory response (nuclear factor (NF)-κB induction and cytokine production) of HaCaT were assessed after in vitro exposure to 10 and 40 µg/mL after 4, 24, and 48 h. Results showed that although both types of coated AgNPs decreased cell proliferation and viability, Cit10 AgNPs were more toxic. NF-κB inhibition was observed for the highest concentration (40 µg/mL) of PEG10 AgNPs, and the putative link to early apoptotic pathways observed in these cells is discussed. No production of IL-1β, IL-6, IL-10, and TNFα was stimulated by AgNPs. Furthermore, Cit10 and PEG10 AgNPs decreased the release of MCP-1 by HaCaT cells after 48 h of exposure. As cytokines are vital for the immunologic regulation in the human body, and it is demonstrated that they may interfere with NPs, more research is needed to understand how different AgNPs affect the immune system.

  20. Microbial diversity of the supra- and subgingival biofilm of healthy individuals after brushing with chlorhexidine- or silver-coated toothbrush bristles.

    Science.gov (United States)

    do Nascimento, Cássio; Paulo, Diana Ferreira; Pita, Murillo Sucena; Pedrazzi, Vinícius; de Albuquerque Junior, Rubens Ferreira

    2015-02-01

    Nanoparticulate silver has recently been reported as an effective antimicrobial agent. The aim of this clinical study was to investigate the potential changes on the oral microbiota of healthy individuals after controlled brushing with chlorhexidine- or silver-coated toothbrush bristles. Twenty-four healthy participants were enrolled in this investigation and randomly submitted to 3 interventions. All the participants received, in a crossover format, the following toothbrushing interventions: (i) chlorhexidine-coated bristles, (ii) silver-coated bristles, and (iii) conventional toothbrush (Control). All the interventions had a duration of 30 days. The DNA checkerboard hybridization method was used to identify and quantify up to 43 microbial species colonizing the supra- and subgingival biofilm. The supragingival samples presented higher genome counts than the subgingival samples (p toothbrush bristles impregnated with silver nanoparticles reduced the total and individual genome count in the supra- and subgingival biofilm after 4 weeks of brushing. Chlorhexidine was not effective in reducing the total genome counts in both supra- or subgingival biofilm after 4 weeks of brushing. Chlorhexidine reduced the individual genome counts in the supragingival biofilm for most of the target species, including putative periodontal pathogens.

  1. Ionizing radiation effect on central venous catheters (CVC) of polyurethane coatings with silver nanoparticles; Efeito da radiacao ionizante nos revestimentos de cateteres venosos centrais (CVC) de poliuretano com nanoparticulas de prata

    Energy Technology Data Exchange (ETDEWEB)

    Heilman, Sonia; Silva, Leonardo G.A., E-mail: sheilman@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Hewer, Thiago L.R.; Souza, Michele L. [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Instituto de Quimica

    2015-07-01

    The present work aimed to study the use of ionizing radiation for coating of silver nanoparticles on central polyurethane catheters, providing reduction of infections associated with contamination of catheters introduced into the bloodstream. Silver nanoparticles have physical, chemical and biological properties only when compared to metal on a macroscopic scale, and have been used in the medical field because of its remarkable antimicrobial activity. Titanium dioxide nanoparticles obtained by the sol gel method were used as the coating catheters for subsequent impregnation of silver nanoparticles with ionizing radiation at doses of 25 and 50 kGy. A Raman spectrometry was used to identify the polymorph of titanium oxide, rutile. In trials with (ICP OES) were evaluated amounts of titanium and silver coated catheters in titanium oxide and silver.(author)

  2. Bendable Electro-chemical Lactate Sensor Printed with Silver Nano-particles

    Science.gov (United States)

    Abrar, Md Abu; Dong, Yue; Lee, Paul Kyuheon; Kim, Woo Soo

    2016-07-01

    Here we report a flexible amperometric lactate biosensor using silver nanoparticle based conductive electrode. Mechanically bendable cross-serpentine-shaped silver electrode is generated on flexible substrate for the mechanical durability such as bending. The biosensor is designed and fabricated by modifying silver electrode with lactate oxidase immobilized by bovine serum albumin. The in-sensor pseudo Ag/AgCl reference electrode is fabricated by chloridization of silver electrode, which evinced its long-term potential stability against a standard commercial Ag/AgCl reference electrode. The amperometric response of the sensor shows linear dependence with lactate concentration of 1~25 mM/L. Anionic selectivity is achieved by using drop-casted Nafion coated on silver electrode against anionic interferences such as ascorbate. This non-invasive electrochemical lactate sensor also demonstrates excellent resiliency against mechanical deformation and temperature fluctuation which leads the possibility of using it on human epidermis for continuous measurement of lactate from sweat. Near field communication based wireless data transmission is demonstrated to reflect a practical approach of the sensor to measure lactate concentration portably using human perspiration.

  3. Silver Nanoparticle-Embedded Thin Silica-Coated Graphene Oxide as an SERS Substrate

    Directory of Open Access Journals (Sweden)

    Xuan-Hung Pham

    2016-09-01

    Full Text Available A hybrid of Ag nanoparticle (NP-embedded thin silica-coated graphene oxide (GO@SiO2@Ag NPs was prepared as a surface-enhanced Raman scattering (SERS substrate. A 6 nm layer of silica was successfully coated on the surface of GO by the physical adsorption of sodium silicate, followed by the hydrolysis of 3-mercaptopropyl trimethoxysilane. Ag NPs were introduced onto the thin silica-coated graphene oxide by the reduction of Ag+ to prepare GO@SiO2@Ag NPs. The GO@SiO2@Ag NPs exhibited a 1.8-fold enhanced Raman signal compared to GO without a silica coating. The GO@SiO2@Ag NPs showed a detection limit of 4-mercaptobenzoic acid (4-MBA at 0.74 μM.

  4. Nafion and modified-Nafion membranes for polymer electrolyte fuel cells: An overview

    Indian Academy of Sciences (India)

    A K Sahu; S Pitchumani; P Sridhar; A K Shukla

    2009-06-01

    Polymer electrolyte fuel cells (PEFCs) employ membrane electrolytes for proton transport during the cell reaction. The membrane forms a key component of the PEFC and its performance is controlled by several physical parameters, viz. water up-take, ion-exchange capacity, proton conductivity and humidity. The article presents an overview on Nafion membranes highlighting their merits and demerits with efforts on modified-Nafion membranes.

  5. Hybrid Antimicrobial Enzyme and Silver Nanoparticle Coatings for Medical Instruments (Postprint)

    Science.gov (United States)

    2009-01-01

    13525), Candida albicans (ATCC 10231), and Staphylococcus epidermidis (ATCC 14990). Bacillus anthracis Sterne strain 34F2 was ob- tained from Colorado...coated blades demonstrated potent bactericidal activity, reducing cell viability by > log 10 within 1.5 h for Klebsiella pneumonia, Bacillus ...anthracis Sterne and Bacillus subtilis and within 3 h for Staphylococcus aureus. The results confirmed that complex antimicrobial coatings can be easily

  6. A novel coated silver ketamine(I electrode for potentiometric determination of ketamine hydrochloride in ampoules and urine samples

    Directory of Open Access Journals (Sweden)

    Hazem M. Abu Shawish

    2014-11-01

    Full Text Available A new ketamine coated silver electrode (KCSE based on ketamine hydrochloride with sodium tetraphenylborate (KT-TPB as electroactive material has been described. The influence of membrane composition, type of solvent mediators, kind of electroactive materials and interfering ions on the sensor was investigated. The sensor displays Nernstian response of 55.8 ± 0.3 mV/decade over the concentration range of 2.5 × 10−6 to 1.0 × 10−2 M with limit of detection of 8.5 × 10−7 M. The coated wire electrode has short response time ∼8 s and it can be used in pH range of 2.6–6.4. The selective coefficients were determined in relation to several inorganic, organic ions, sugars and some common drug excipients. The KCSE electrode was successfully used for the determination of the ketamine content in ampoule and urine samples with satisfactory results. Statistical student’s t-test and F test showed insignificant systematic error between proposed and official methods.

  7. In situ synthesis of silver nanoparticles uniformly distributed on polydopamine-coated silk fibers for antibacterial application.

    Science.gov (United States)

    Lu, Zhisong; Xiao, Jing; Wang, Ying; Meng, Mei

    2015-08-15

    Fabrication of silver nanoparticles (AgNPs)-modified silk for antibacterial application is one of the hottest topics in the textile material research. However, the utilization of a polymer as both 3-dimensional matrix and reductant for the in-situ synthesis of AgNPs on silk fibers has not been realized. In this work, a facile, efficient and green approach was developed to in-situ grow AgNPs on the polydopamine (PDA)-functionalized silk. AgNPs with the size of 30-90 nm were uniformly deposited on the silk fiber surface with the PDA coating layer as a reduction reagent. The AgNPs exhibit excellent face-centered cubic crystalline structures. The bacterial growth curve and inhibition zone assays clearly demonstrate the antibacterial properties of the functionalized silk. Both high Ag(+) release level and long-time release profile were observed for the as-prepared AgNPs-PDA-coated silk, indicating the high-density loading of AgNPs and the possible long-term antibacterial effects. This work may provide a new method for the preparation of AgNPs-functionalized silk with antibacterial activity for the clothing and textile industry.

  8. Physicochemical characterization of 3,6-diHydroxyflavone binding BSA immobilized on PEG-coated silver nanoparticles

    Science.gov (United States)

    Voicescu, Mariana; Ionescu, Sorana; Calderon-Moreno, Jose M.; Nistor, Cristina L.

    2017-02-01

    Studies based on silver nanoparticles (SNPs) and polyethylene glycols (PEGs) are mainly in the pharmaceutical field, with PEG as good "vehicle" to transport protein-based drugs. In this work, physicochemical characteristics of 3,6-diHydroxyflavone (3,6-diHF) binding bovine serum albumin (BSA) on PEG (Tween20, L64, and Myrj52)-coated SNPs have been investigated by steady-state and time-resolved fluorescence spectroscopy. These interactions give rise to the formation of intermolecular and intramolecular H bonds. As a subject of interest, the effect of temperature (30-60 °C) on the H bonds was studied by steady-state fluorescence. The size distribution and zeta potential of SNPs were determined by dynamic light scattering (DLS). Scanning electron microscopy (SEM) analysis revealed the spherical nature of particles with average diameter 40-80 nm. The structure, stability, dynamics, and conformational changes in adsorbed BSA protein on the PEG-coated SNPs surface have been also investigated by steady-state/lifetime fluorescence and circular dichroism spectroscopy. The results have relevance in the oxidative stress and drug delivery processes.

  9. Bactericidal effects of silver plus titanium dioxide-coated endotracheal tubes on Pseudomonas aeruginosa and Staphylococcus aureus

    Directory of Open Access Journals (Sweden)

    Keiko M Tarquinio

    2010-03-01

    Full Text Available Keiko M Tarquinio1, Nikhil K Kothurkar2, Dharendra Y Goswami3, Ronald C Sanders Jr4, Arno L Zaritsky5, Ann Marie LeVine61Division of Pediatric Critical Care Medicine, Department of Pediatrics, Rhode Island Hospital, The Warren Alpert Medical School, Brown University, Providence, RI USA; 2Department of Chemical Engineering and Materials Science, Amrita School of Engineering, Ettimadai, Coimbatore, India; 3Clean Energy Research Center, University of South Florida, Tampa, FL, USA; 4Section of Pediatric Critical Care, Department of Pediatrics, College of Medicine, University of Arkansas for Medical Sciences, Arkansas Children’s Hospital, Little Rock, AR, USA; 5Executive Medical Director, Children’s Hospital of The King’s Daughters, Norfolk, VA, USA; 6Pediatric Critical Care Medicine, University of Michigan Medical School, C.S. Mott Children’s Hospital, Ann Arbor, MI, USAPurpose: Ventilator-associated pneumonia (VAP is a nosocomial infection resulting in significant morbidity and mortality. Pseudomonas aeruginosa (P. aeruginosa and Staphylococcus aureus (S. aureus are pathogens associated with VAP. Silver (Ag coating of endotracheal tubes (ETTs reduces bacterial colonization, however titanium dioxide (TiO2 coating has not been studied.Methods: Five types of ETT coatings were applied over silica layer: Ag, solgel TiO2, solgel TiO2 with Ag, Degussa P25 TiO2 (Degussa TiO2, and Degussa TiO2 with Ag. After ETTs were incubated with P. aeruginosa or S. aureus; colonization was determined quantitatively.Results: Pseudomonas aeruginosa and S. aureus grew for 5 days on standard ETTs. Compared to standard ETTs, P. aeruginosa growth was significantly inhibited by solgel TiO2 with Ag at 24 hours, and by Degussa TiO2 with Ag at 24 and 48 hours after inoculation. No significant difference in S. aureus growth was observed between the control and any of the five coatings for 5 days.Conclusion: In vitro, solgel TiO2 with Ag and Degussa TiO2 with Ag both

  10. Antibacterial properties and cytocompatibility of tantalum oxide coatings with different silver content

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Heng-Li [School of Dentistry, China Medical University, Taichung 404, Taiwan (China); Chang, Yin-Yu, E-mail: yinyu@mail2000.com.tw; Chen, Hung-Jui; Chou, Yu-Kai [Department of Mechanical and Computer-Aided Engineering, National Formosa University, Yunlin 632, Taiwan (China); Lai, Chih-Ho [School of Medicine, China Medical University, Taichung 404, Taiwan (China); Chen, Michael Y. C. [Division of Oral and Maxillofacial Surgery, China Medical University Hospital, Taichung 404, Taiwan (China)

    2014-03-15

    Tantalum (Ta) oxides and their coatings have been proved to increase their applications in the biomedical fields by improving osseointegration and wear resistance. In this study, Ta oxide coatings containing different proportions of Ag are deposited on SS304 materials. A twin-gun magnetron sputtering system is used to deposit the tantalum oxide-Ag coating. In this study, Staphylococcus aureus, which exhibits physiological commensalism on the human skin, nares, and mucosal and oral areas, is chosen as the model for in vitro antibacterial analyses via a fluorescence staining method using Syto9. The cytocompatibility and adhesive morphology of human skin fibroblast cells (CCD-966SK) on the coatings are also determined by using the microculture tetrazolium assay. This study shows that Ta{sub 2}O{sub 5} and Ta{sub 2}O{sub 5}-Ag coatings with 12.5 at. % of Ag exhibit improved antibacterial effects against S. aureus and have good skin fibroblast cell cellular biocompatibility.

  11. Effect of a nano-silver coating on the quality of fresh turkey meat during storage after modified atmosphere or vacuum packaging.

    Science.gov (United States)

    Deus, D; Kehrenberg, C; Schaudien, D; Klein, G; Krischek, C

    2017-02-01

    Nano-silver is used in consumer products due to its antibacterial properties. The aim of this study was to evaluate the effect of a nano-silver-coated film on the quality of turkey meat during vacuum-sealed and modified atmosphere packaging up to 12 days of storage. In the first part of the experiment, turkey breasts were packaged using either vacuum packaging or modified atmosphere packages (MAPs) and contained films with or without a nano-silver coating (control film). Parameters such as pH, electrical conductivity, color (lightness L*, redness a*), myoglobin redox forms, thiobarbituric acid-reactive substances (TBARS), biogenic amines (BAs), total viable bacterial counts, Pseudomonas species counts, and Enterobacteriaceae species counts were evaluated on storage days 4, 8, and 12. In the second part of the study, the antimicrobial effect of a nano-silver-coated film on turkey breast was evaluated after inoculation with Escherichia coli (E. coli). Turkey meat packaged with the nano-silver film exhibited lower a* values on days 1 (3.15 ± 0.62), 4 (3.90 ± 0.68), and 8 (4.27 ± 0.76) compared to the packaged meat with the control film (3.41 ± 0.73, 4.35 ± 0.94, 4.85 ± 0.89, respectively), indicating special optical properties of nanoparticles. Concerning the BAs, silver packaged meat showed higher values of tyramine on day 12 (1274 ± 392 ng/g meat) and cadaverine on day 4 (1224 ± 435 ng/g meat) compared to the normal packaged products (647 ± 576 and 508 ± 314 ng/g meat, respectively). MAP meat revealed higher L* and TBARS values and lower microbial counts than the vacuum packaged products on all days. The MAP meat also showed lower a* results on days 4 and 8 and higher metmyoglobin (metMb) values on days 8 and 12 compared to th E: vacuum products. In the inoculation study, the microbial counts of the turkey meat were comparable between the two film types. The study showed that the nano-silver coating did not exhibit any advantageous

  12. Fabrication of a polymer-coated silver hollow optical fiber with high performance

    Science.gov (United States)

    Shi, Yi-Wei; Ito, Kentaro; Ma, Lin; Yoshida, Takanori; Matsuura, Yuji; Miyagi, Mitsunobu

    2006-09-01

    The techniques for fabricating a hollow optical fiber with an inner silver layer and a cyclic olefin polymer (COP) layer have been improved to reduce the surface roughness of these two layers. The loss spectrum was thereby drastically reduced over a wide wavelength range, from visible to near infrared. Optimization of the COP layer thickness resulted in low loss simultaneously at several key laser wavelengths. Infrared hollow fiber with low loss was developed for Er:YAG and Nd:YAG lasers. It can also deliver green and red pilot beams with low loss. Use of this fiber in therapeutic and pilot lasers should prove useful for research and development in laser medicine.

  13. Detection of H2O2 at a composite film modified electrode with highly dispersed Ag nanoparticles in Nafion

    Institute of Scientific and Technical Information of China (English)

    Mei Xiu Kan; Xue Ji Wang; Hui Min Zhang

    2011-01-01

    Ag nanoparticles were prepared by using the ion-exchange of Nafion combined with electrochemical reduction on the electrode. Ag nanoparticles are highly dispersed in Nafion film with an average size of 4.0 ± 0.2 nm. The amount of Ag nanoparticles can be readily controlled by the amount of Nafion coated on the electrode. Thus obtained Ag nanoparticles exhibit good catalytic activity for the reduction of H2O2 with a linear response to H2O2 in the concentration range of 0.04-8.0 mmol/L with a sensitivity of 0.34 μA/mmol/L and a detection limit of 1.0×10-8 mol/L.

  14. Study on preparation and properties of micro silver-coated copper powders%银包覆铜微粉的制备与性能研究

    Institute of Scientific and Technical Information of China (English)

    李雅丽; 刘娟; 党蕊

    2011-01-01

    By using CuSO4 · 5H2O as raw materials, the micro size of copper powders were prepared by pre-reduction method using glucose in the ethylene glycol medium, and the micro silver type of copper-coated powders were directly obtained through replacement reaction method. By means of experiment of conductivity, and analysis of the particle size and distribution, the optimum technology condition was confirmed to prepare the micro silver-coated copper powders.%以硫酸铜为原料,采用葡萄糖预还原法在乙二醇介质中制备微米级铜粉,由直接置换法制备铜包银型微粉;通过导电性实验、粒径及粒径分布分析等,优化了制备银包覆铜微粉的工艺条件.

  15. Femtosecond laser induced breakdown spectroscopy of silver within surrogate high temperature gas reactor fuel coated particles

    CSIR Research Space (South Africa)

    Roberts, DE

    2010-11-01

    Full Text Available been studied with femtosecond Laser Induced Breakdown Spectroscopy (femto-LIBS). The SiC layer of the TRISO coated particle is the main barrier to metallic and gaseous fission products of which 110mAg is of particular interest for direct cycle high...

  16. Cytotoxicity of β-D-glucose/sucrose-coated silver nanoparticles depends on cell type, nanoparticles concentration and time of incubation

    Science.gov (United States)

    Vergallo, Cristian; Panzarini, Elisa; Carata, Elisabetta; Ahmadi, Meysam; Mariano, Stefania; Tenuzzo, Bernardetta Anna; Dini, Luciana

    2016-06-01

    The use of silver NanoParticles (AgNPs) in several consumer commercialized products, like food contact materials, medical devices and cosmetics has increased significantly, owing to their antibacterial and antifungal properties. Even though the NPs are widely diffused, due to the great variety in size, coating or shape, controversial data on their possible detrimental health effects still exist. Herein, by performing an easy and fast green method synthesis, we used β-D-glucose/sucrose to stabilize AgNPs and avoid the release of cytotoxic soluble silver ions Ag+ in the culture medium. The cytotoxic effects of these β-D-Glucose/Sucrose-Coated AgNPs (AgNPs-GS) was assessed on two cell culture models, which are human liver HepG2 and human Peripheral Blood Lymphocytes (PBLs) cells. AgNPs-GS, as determined by Transmission Electron Microscopy (TEM) analyses, had an average diameter of 30±5 nm, a spherical shape and were well-dispersed in the freshly-prepared solution. In addition, they were found spectrophotometrically stable throughout the experiment. Cytotoxicity, determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction assay, was evaluated by using two AgNPs-GS amounts, indicated as highest (10×103 of NPs/cell) and lowest (2×103 NPs/cell) concentration for 6, 12 and 24 h. The highest concentration of AgNPs-GS was significantly cytotoxic for both HepG2 and PBLs cells at all times, when compared with the negative control; conversely, the lowest amount of AgNPs-GS was toxic only for HepG2 cells. A significant increase of Reactive Oxygen Species (ROS) levels, determined by Nitro Blue Tetrazolium (NBT) reduction assay, was observed only in PBLs after treatment with NPs, by reaching maximum levels after the incubation with the lowest amount of NPs for 24 h. Significant morphological changes, depending on NPs/cell amount, characteristic of cell toxicity, like shape, cytoplasm, and nucleus alterations, were observed in lymphocytes and Hep

  17. Label-free SERS detection of relevant bioanalytes on silver-coated carbon nanotubes: The case of cocaine

    Science.gov (United States)

    Sanles-Sobrido, Marcos; Rodríguez-Lorenzo, Laura; Lorenzo-Abalde, Silvia; González-Fernández, África; Correa-Duarte, Miguel A.; Alvarez-Puebla, Ramón A.; Liz-Marzán, Luis M.

    2009-09-01

    Surface-enhanced Raman scattering (SERS) spectroscopy can be used for the label-free determination and quantification of relevant small biometabolites that are hard to identify by conventional immunological methods, in the absence of labelling. In this work, detection is based on monitoring the vibrational changes occurring at a specific biointerface (a monoclonal antibody, mAb) supported on silver-coated carbon nanotubes (CNT@Ag). Engineered CNT@Ag play a key role, as they offer a stable substrate to support the biointerface, with a high density of hot spots. Proof of concept is demonstrated through the analysis and quantification of the main cocaine metabolite benzoylecgonine. These results open a new avenue toward the generation of portable sensors for fast ultradetection and quantification of relevant metabolites. The use of discrete particles (CNT@Ag@mAb) rather than rough films, or other conventional SERS supports, will also enable a safe remote interrogation of highly toxic sources in environmental problems or in biological fluids.Surface-enhanced Raman scattering (SERS) spectroscopy can be used for the label-free determination and quantification of relevant small biometabolites that are hard to identify by conventional immunological methods, in the absence of labelling. In this work, detection is based on monitoring the vibrational changes occurring at a specific biointerface (a monoclonal antibody, mAb) supported on silver-coated carbon nanotubes (CNT@Ag). Engineered CNT@Ag play a key role, as they offer a stable substrate to support the biointerface, with a high density of hot spots. Proof of concept is demonstrated through the analysis and quantification of the main cocaine metabolite benzoylecgonine. These results open a new avenue toward the generation of portable sensors for fast ultradetection and quantification of relevant metabolites. The use of discrete particles (CNT@Ag@mAb) rather than rough films, or other conventional SERS supports, will also

  18. Toxicity and antibacterial assessment of chitosan-coated silver nanoparticles on human pathogens and macrophage cells

    Directory of Open Access Journals (Sweden)

    Jena P

    2012-04-01

    Full Text Available Prajna Jena1, Soumitra Mohanty1, Rojee Mallick1, Biju Jacob2, Avinash Sonawane11School of Biotechnology, KIIT University, Bhubaneswar, Orissa, India; 2Center for Innovation, Technopark Technology Business Incubator, Bangalore, Karnataka, IndiaBackground: Pathogenic bacteria are able to develop various strategies to counteract the bactericidal action of antibiotics. Silver nanoparticles (AgNPs have emerged as a potential alternative to conventional antibiotics because of their potent antimicrobial properties. The purpose of this study was to synthesize chitosan-stabilized AgNPs (CS-AgNPs and test for their cytotoxic, genotoxic, macrophage cell uptake, antibacterial, and antibiofilm activities.Methods: AgNPs were synthesized using chitosan as both a stabilizing and a reducing agent. Antibacterial activity was determined by colony-forming unit assay and scanning electron microscopy. Genotoxic and cytotoxic activity were determined by DNA fragmentation, comet, and MTT [3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide] assays. Cellular uptake and intracellular antibacterial activity were tested on macrophages.Results: CS-AgNPs exhibited potent antibacterial activity against different human pathogens and also impeded bacterial biofilm formation. Scanning electron microscopy analysis indicated that CS-AgNPs kill bacteria by disrupting the cell membrane. CS-AgNPs showed no significant cytotoxic or DNA damage effect on macrophages at the bactericidal dose. Propidium iodide staining indicated active endocytosis of CS-AgNPs resulting in reduced intracellular bacterial survival in macrophages.Conclusion: The present study concludes that at a specific dose, chitosan-based AgNPs kill bacteria without harming the host cells, thus representing a potential template for the design of antibacterial agents to decrease bacterial colonization and to overcome the problem of drug resistance.Keywords: chitosan-silver nanoparticles, antibiofilm, cytotoxicity

  19. Modeling of ion conductivity in Nafion membranes

    Institute of Scientific and Technical Information of China (English)

    YANG Zhen; PENG Xiaofeng; WANG Buxuan; LEE Duujong; DUAN Yuanyuan

    2007-01-01

    A theoretical investigation was conducted to describe the ion transport behavior in a Nafion Membrane of proton exchange membrane fuel cells (PEMFC).By analyzing the surface energy configuration of the ionic clusters in a Nafion membrane,an equivalent field intensity,Ee,was introduced to facilitate the analysis of surface resistance against ion conduction in the central region of clusters.An expression was derived for ionic conductivity incorporating the influence of surface resistance.A face-centered cubic (FCC)lattice model for a spatial cluster distribution was used to modify the effect of water content on ionic conductivity in the polymeric matrix,i.e.,the regions between clusters.Compared with the available empirical correlations,the new expression showed much better agreement with the available experimental results,which indicates the rationality to consider the structural influence on ion conduction in water-swollen Nation membranes.

  20. Silver (Ag) Transport Mechanisms in TRISO coated particles: A Critical Review

    Energy Technology Data Exchange (ETDEWEB)

    I J van Rooyen; J H Neethling; J A A Engelbrecht; P M van Rooyen; G Strydom

    2012-10-01

    Transport of 110mAg in the intact SiC layer of TRISO coated particles has been studied for approximately 30 years without arriving at a satisfactory explanation of the transport mechanism. In this paper the possible mechanisms postulated in previous experimental studies, both in-reactor and out-of reactor research environment studies are critically reviewed and of particular interest are relevance to very high temperature gas reactor operating and accident conditions. Among the factors thought to influence Ag transport are grain boundary stoichiometry, SiC grain size and shape, the presence of free silicon, nano-cracks, thermal decomposition, palladium attack, transmutation products, layer thinning and coated particle shape. Additionally new insight to nature and location of fission products has been gained via recent post irradiation electron microscopy examination of TRISO coated particles from the DOE’s fuel development program. The combined effect of critical review and new analyses indicates a direction for investigating possible the Ag transport mechanism including the confidence level with which these mechanisms may be experimentally verified.

  1. High dielectric, dynamic mechanical and thermal properties of polyimide composite film filled with carbon-coated silver nanowires

    Science.gov (United States)

    Wang, Lisi; Piao, Xiaoyu; Zou, Heng; Wang, Ya; Li, Hengfeng

    2015-01-01

    High dielectric permittivity materials are much desirable in the electric industry. Filling polymer matrix with conductive powders to form percolative composites is one of the most promising methods to achieve high dielectric permittivity. However, they do not always provide high mechanical properties and thermal stability, which seriously limit their applications. In this study, we present the preparation of functional core-shell structured silver nanowires/polyimide (AgNWs/PI) hybrid film with high dielectric permittivity and low loss dielectric. The core-shell structure of AgNWs was characterized by transmission electric microscopy. The dynamical mechanical analysis showed that AgNWs/PI hybrid films had relative high dynamic mechanical properties with storage modules over 1 Gpa. Moreover, the hybrid films exhibited excellent thermal stability with 5 % weight-loss temperature above 500 °C. The dielectric properties of the carbon-coated AgNWs hybrid films were remarkably improved. The maximum dielectric permittivity of hybrid films is 126 at 102 Hz, which was 39 times higher than that of pure PI matrix, while the dielectric loss of that is still remained at a low value. This study showed a new method to improve the dielectric, dynamic mechanical and thermal properties of films.

  2. Newly designed silver coated-magnetic, monodisperse polymeric microbeads as SERS substrate for low-level detection of amoxicillin

    Science.gov (United States)

    Kibar, Güneş; Topal, Ahmet Emin; Dana, Aykutlu; Tuncel, Ali

    2016-09-01

    We report the preparation of silver-coated magnetic polymethacrylate core-shell nanoparticles for use in surface-enhanced Raman scattering based drug detection. Monodisperse porous poly (mono-2-(methacryloyloxy)ethyl succinate-co-glycerol dimethacrylate), poly (MMES-co-GDMA) microbeads of ca. 5 μm diameter were first synthesized through a multistage microsuspension polymerization technique to serve as a carboxyl-bearing core region. Microspheres were subsequently magnetized by the co-precipitation of ferric ions, aminated through the surface hydroxyl groups and decorated with Au nanoparticles via electrostatic attraction. An Ag shell was then formed on top of the Au layer through a seed-mediated growth process, resulting in micron-sized monodisperse microbeads that exhibit Raman enhancement effects due to the roughness of the Ag surface layer. The core-shell microspheres were used as a new substrate for the detection of amoxicillin at trace concentrations up to 10-8 M by SERS. The proposed SERS platform can be evaluated as a useful tool for the follow-up amoxicillin pollution and low-level detection of amoxicillin in aqueous media.

  3. Controllable in situ synthesis of silver nanoparticles on multilayered film-coated silk fibers for antibacterial application.

    Science.gov (United States)

    Meng, Mei; He, Huawei; Xiao, Jing; Zhao, Ping; Xie, Jiale; Lu, Zhisong

    2016-01-01

    Layer-by-layer (LbL) assembly is a versatile technique for the preparation of multilayered polymeric films. However, fabrication of LbL polymetic film on silk for the in situ growth of high-density silver nanoparticles (AgNPs) has not been realized. Herein poly(acrylic acid) (PAA)/poly(dimethyldiallylammonium chloride) (PDDA) multilayers are constructed on silk via the LbL approach, subsequently serving as a 3-dimensional matrix for in situ synthesis of AgNPs. After 8 rounds of LbL assembly, the silk is fully covered with a layer of polymeric film. AgNPs with good crystalline structures could be in-situ generated in the silk-coated multilayers and their amount could be tailored by adjusting the bilayer numbers. The as-prepared silk could effectively kill the existing bacteria and inhibit the bacterial growth, demonstrating the antimicrobial activity. Moreover, the release of Ag(+) from the modified silk can last for 120 h, rendering the modified silk sustainable antimicrobial activity. This work may provide a novel method to prepare AgNPs-functionalized antimicrobial silk for potential applications in textile industry.

  4. Annealing-free, flexible silver nanowire-polymer composite electrodes via a continuous two-step spray-coating method.

    Science.gov (United States)

    Choi, Dong Yun; Kang, Hyun Wook; Sung, Hyung Jin; Kim, Sang Soo

    2013-02-07

    For the realization of high-efficiency flexible optoelectronic devices, transparent electrodes should be fabricated through a low-temperature process and have the crucial feature of low surface roughness. In this paper, we demonstrated a two-step spray-coating method for producing large-scale, smooth and flexible silver nanowire (AgNW)-poly3,4-ethylenedioxythiophene:polystyrenesulfonate (PEDOT:PSS) composite electrodes. Without the high-temperature annealing process, the conductivity of the composite film was improved via the lamination of highly conductive PEDOT:PSS modified by dimethyl sulfoxide (DMSO). Under the room temperature process condition, we fabricated the AgNW-PEDOT:PSS composite film showing an 84.3% mean optical transmittance with a 10.76 Ω sq(-1) sheet resistance. The figure of merit Φ(TC) was higher than that obtained from the indium tin oxide (ITO) films. The sheet resistance of the composite film slightly increased less than 5.3% during 200 cycles of tensile and compression folding, displaying good electromechanical flexibility for use in flexible optoelectronic applications.

  5. PVP-coated silver nanoparticles block the transmission of cell-free and cell-associated HIV-1 in human cervical culture

    Directory of Open Access Journals (Sweden)

    Rodriguez-Padilla Cristina

    2010-07-01

    Full Text Available Abstract Background Previous in vitro studies have demonstrated that polyvinylpyrrolidone coated silver nanoparticles (PVP-coated AgNPs have antiviral activity against HIV-1 at non-cytotoxic concentrations. These particles also demonstrate broad spectrum virucidal activity by preventing the interaction of HIV-1 gp120 and cellular CD4, thereby inhibiting fusion or entry of the virus into the host cell. In this study, we evaluated the antiviral activity of PVP-coated AgNPs as a potential topical vaginal microbicide to prevent transmission of HIV-1 infection using human cervical culture, an in vitro model that simulates in vivo conditions. Results When formulated into a non-spermicidal gel (Replens at a concentration of 0.15 mg/mL, PVP-coated AgNPs prevented the transmission of cell-associated HIV-1 and cell-free HIV-1 isolates. Importantly, PVP-coated AgNPs were not toxic to the explant, even when the cervical tissues were exposed continuously to 0.15 mg/mL of PVP-coated AgNPs for 48 h. Only 1 min of PVP-coated AgNPs pretreatment to the explant was required to prevent transmission of HIV-1. Pre-treatment of the cervical explant with 0.15 mg/mL PVP-coated AgNPs for 20 min followed by extensive washing prevented the transmission of HIV-1 in this model for 48 h. Conclusions A formulation of PVP-coated AgNPs homogenized in Replens gel acts rapidly to inhibit HIV-1 transmission after 1 min and offers long-lasting protection of the cervical tissue from infection for 48 h, with no evidence of cytotoxicity observed in the explants. Based on this data, PVP-coated AgNPs are a promising microbicidal candidate for use in topical vaginal/cervical agents to prevent HIV-1 transmission, and further research is warranted.

  6. The potential use of a layer-by-layer strategy to develop LDPE antimicrobial films coated with silver nanoparticles for packaging applications.

    Science.gov (United States)

    Azlin-Hasim, Shafrina; Cruz-Romero, Malco C; Cummins, Enda; Kerry, Joseph P; Morris, Michael A

    2016-01-01

    Commercial low-density polyethylene (LDPE) films were UV/ozone treated and coated using a layer-by-layer (LbL) technique by alternating the deposition of polyethyleneimine (PEI) and poly(acrylic acid) (PAA) polymer solutions and antimicrobial silver (Ag). The effects of the initial pH of the PEI/PAA polymer solutions alternating layers (pH 10.5/4 or 9/6.5) on the antimicrobial activity of the developed LbL coatings combined with Ag against Gram-negative and Gram-positive bacteria were investigated. The results from fourier transform infrared spectroscopy and toluidine blue O assay showed that LDPE LbL coated using PEI/PAA polymer solutions with initial pH of 10.5/4 significantly increased the presence of carboxylic acid groups and after Ag attachment the coating had higher antimicrobial activity against both Gram-negative and Gram-positive bacteria compared to the LDPE LbL coated using PEI/PAA polymer solutions with initial pH of 9/6.5. The LDPE LbL coated films using non-modified pH PEI/PAA polymer solutions decreased the water contact-angle indicating an increased hydrophilicity of the film, also increased the tensile strength and roughness of LDPE LbL coated films compared to uncoated LbL samples. The LDPE LbL coated films attached with Ag(+) were UV/ozone treated for 20 min to oxidise Ag(+) to Ag(0). The presence of Ag(0) (Ag nanoparticles (NPs)) on the LDPE LbL coated films was confirmed by XRD, UV-vis spectrophotometer and colour changes. The overall results demonstrated that the LbL technique has the potential to be used as a coating method containing antimicrobial Ag NPs and that the manufactured films could potentially be applied as antimicrobial packaging.

  7. Cleanable and Hardcoat Coatings for Increased Durability of Silvered Polymeric Mirrors

    Energy Technology Data Exchange (ETDEWEB)

    Padiyath, Raghunath

    2013-05-01

    We have successfully developed coating formulations which significantly increasethe abrasion resistance of mirror films. We have demonstrated manufacturing scale-up of these films to full width andproduction volumes. Implementation of these films in commercial test sites is planned for Q2 2013(Abengoa, Gossamer Space Frames). This slide show outlines the background and objectives of the project, technical approach and results, and key lessons. It also presents the need and opportunity for reduction of costs for CSP and collectors. It also presents an approach for a large aperture parabolic trough collector with reflective film and a high concentration factor, including demonstration and results.

  8. In vitro and in vivo evaluation of biologically synthesized silver nanoparticles for topical applications: effect of surface coating and loading into hydrogels.

    Science.gov (United States)

    Mekkawy, Aml I; El-Mokhtar, Mohamed A; Nafady, Nivien A; Yousef, Naeima; Hamad, Mostafa A; El-Shanawany, Sohair M; Ibrahim, Ehsan H; Elsabahy, Mahmoud

    2017-01-01

    In the present study, silver nanoparticles (AgNPs) were synthesized via biological reduction of silver nitrate using extract of the fungus Fusarium verticillioides (green chemistry principle). The synthesized nanoparticles were spherical and homogenous in size. AgNPs were coated with polyethylene glycol (PEG) 6000, sodium dodecyl sulfate (SDS), and β-cyclodextrin (β-CD). The averaged diameters of AgNPs were 19.2±3.6, 13±4, 14±4.4, and 15.7±4.8 nm, for PEG-, SDS-, and β-CD-coated and uncoated AgNPs, respectively. PEG-coated AgNPs showed greater stability as indicated by a decreased sedimentation rate of particles in their water dispersions. The antibacterial activities of different AgNPs dispersions were investigated against Gram-positive bacteria (methicillin-sensitive and methicillin-resistant Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli) by determination of the minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs). MIC and MBC values were in the range of 0.93-7.5 and 3.75-15 µg/mL, respectively, which were superior to the reported values in literature. AgNPs-loaded hydrogels were prepared from the coated-AgNPs dispersions using several gelling agents (sodium carboxymethyl cellulose [Na CMC], sodium alginate, hydroxypropylmethyl cellulose, Pluronic F-127, and chitosan). The prepared formulations were evaluated for their viscosity, spreadability, in vitro drug release, and antibacterial activity, and the combined effect of the type of surface coating and the polymers utilized to form the gel was studied. The in vivo wound-healing activity and antibacterial efficacy of Na CMC hydrogel loaded with PEG-coated AgNPs in comparison to the commercially available silver sulfadiazine cream (Dermazin(®)) were evaluated. Superior antibacterial activity and wound-healing capability, with normal skin appearance and hair growth, were demonstrated for the hydrogel formulations, as compared to the silver

  9. In vitro and in vivo evaluation of biologically synthesized silver nanoparticles for topical applications: effect of surface coating and loading into hydrogels

    Science.gov (United States)

    Mekkawy, Aml I; El-Mokhtar, Mohamed A; Nafady, Nivien A; Yousef, Naeima; Hamad, Mostafa A; El-Shanawany, Sohair M; Ibrahim, Ehsan H; Elsabahy, Mahmoud

    2017-01-01

    In the present study, silver nanoparticles (AgNPs) were synthesized via biological reduction of silver nitrate using extract of the fungus Fusarium verticillioides (green chemistry principle). The synthesized nanoparticles were spherical and homogenous in size. AgNPs were coated with polyethylene glycol (PEG) 6000, sodium dodecyl sulfate (SDS), and β-cyclodextrin (β-CD). The averaged diameters of AgNPs were 19.2±3.6, 13±4, 14±4.4, and 15.7±4.8 nm, for PEG-, SDS-, and β-CD-coated and uncoated AgNPs, respectively. PEG-coated AgNPs showed greater stability as indicated by a decreased sedimentation rate of particles in their water dispersions. The antibacterial activities of different AgNPs dispersions were investigated against Gram-positive bacteria (methicillin-sensitive and methicillin-resistant Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli) by determination of the minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs). MIC and MBC values were in the range of 0.93–7.5 and 3.75–15 µg/mL, respectively, which were superior to the reported values in literature. AgNPs-loaded hydrogels were prepared from the coated-AgNPs dispersions using several gelling agents (sodium carboxymethyl cellulose [Na CMC], sodium alginate, hydroxypropylmethyl cellulose, Pluronic F-127, and chitosan). The prepared formulations were evaluated for their viscosity, spreadability, in vitro drug release, and antibacterial activity, and the combined effect of the type of surface coating and the polymers utilized to form the gel was studied. The in vivo wound-healing activity and antibacterial efficacy of Na CMC hydrogel loaded with PEG-coated AgNPs in comparison to the commercially available silver sulfadiazine cream (Dermazin®) were evaluated. Superior antibacterial activity and wound-healing capability, with normal skin appearance and hair growth, were demonstrated for the hydrogel formulations, as compared to the silver

  10. Pulmonary toxicity of instilled silver nanoparticles: influence of size, coating and rat strain.

    Directory of Open Access Journals (Sweden)

    Joanna Seiffert

    Full Text Available Particle size and surface chemistry are potential determinants of silver nanoparticle (AgNP respiratory toxicity that may also depend on the lung inflammatory state. We compared the effects of intratracheally-administered AgNPs (20 nm and 110 nm; polyvinylpyrrolidone (PVP and citrate-capped; 0.1 mg/Kg in Brown-Norway (BN and Sprague-Dawley (SD rats. In BN rats, there was both a neutrophilic and eosinophilic response, while in SD rats, there was a neutrophilic response at day 1, greatest for the 20 nm citrate-capped AgNPs. Eosinophilic cationic protein was increased in bronchoalveolar lavage (BAL in BN and SD rats on day 1. BAL protein and malondialdehyde levels were increased in BN rats at 1 and 7 days, and BAL KC, CCL11 and IL-13 levels at day 1, with increased expression of CCL11 in lung tissue. Pulmonary resistance increased and compliance decreased at day 1, with persistence at day 7. The 20 nm, but not the 110 nm, AgNPs increased bronchial hyperresponsiveness on day 1, which continued at day 7 for the citrate-capped AgNPs only. The 20 nm versus the 110 nm size were more proinflammatory in terms of neutrophil influx, but there was little difference between the citrate-capped versus the PVP-capped AgNPs. AgNPs can induce pulmonary eosinophilic and neutrophilic inflammation with bronchial hyperresponsiveness, features characteristic of asthma.

  11. Pulmonary toxicity of instilled silver nanoparticles: influence of size, coating and rat strain.

    Science.gov (United States)

    Seiffert, Joanna; Hussain, Farhana; Wiegman, Coen; Li, Feng; Bey, Leo; Baker, Warren; Porter, Alexandra; Ryan, Mary P; Chang, Yan; Gow, Andrew; Zhang, Junfeng; Zhu, Jie; Tetley, Terry D; Chung, Kian Fan

    2015-01-01

    Particle size and surface chemistry are potential determinants of silver nanoparticle (AgNP) respiratory toxicity that may also depend on the lung inflammatory state. We compared the effects of intratracheally-administered AgNPs (20 nm and 110 nm; polyvinylpyrrolidone (PVP) and citrate-capped; 0.1 mg/Kg) in Brown-Norway (BN) and Sprague-Dawley (SD) rats. In BN rats, there was both a neutrophilic and eosinophilic response, while in SD rats, there was a neutrophilic response at day 1, greatest for the 20 nm citrate-capped AgNPs. Eosinophilic cationic protein was increased in bronchoalveolar lavage (BAL) in BN and SD rats on day 1. BAL protein and malondialdehyde levels were increased in BN rats at 1 and 7 days, and BAL KC, CCL11 and IL-13 levels at day 1, with increased expression of CCL11 in lung tissue. Pulmonary resistance increased and compliance decreased at day 1, with persistence at day 7. The 20 nm, but not the 110 nm, AgNPs increased bronchial hyperresponsiveness on day 1, which continued at day 7 for the citrate-capped AgNPs only. The 20 nm versus the 110 nm size were more proinflammatory in terms of neutrophil influx, but there was little difference between the citrate-capped versus the PVP-capped AgNPs. AgNPs can induce pulmonary eosinophilic and neutrophilic inflammation with bronchial hyperresponsiveness, features characteristic of asthma.

  12. Strontium incorporation to optimize the antibacterial and biological characteristics of silver-substituted hydroxyapatite coating.

    Science.gov (United States)

    Geng, Zhen; Cui, Zhenduo; Li, Zhaoyang; Zhu, Shengli; Liang, Yanqin; Liu, Yunde; Li, Xue; He, Xin; Yu, Xiaoxu; Wang, Renfeng; Yang, Xianjin

    2016-01-01

    Infection in primary total joint prostheses is attracting considerable attention. In this study, silver (Ag) was incorporated into hydroxyapatite (HA) using a hydrothermal method in order to improve its antimicrobial properties. Strontium (Sr) was added as a second binary element to improve the biocompatibility. The substituted HA samples were fixed on titanium (Ti) substrates by dopamine-assisted immobilization in order to evaluate their antibacterial and biological properties. The results showed that Ag and Sr were successfully incorporated into HA without affecting their crystallinity. Further, the antibacterial tests showed that all the Ag-substituted samples had good anti-bacterial properties against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Despite their good antibacterial ability, the Ag-substituted samples showed evidence of cytotoxicity on MG63 cells, characterized by low cell density and poor spreadability. The addition of Sr to the Ag-substituted samples considerably reduced the cytotoxicity of Ag. Although the viability of the cells grown on the surfaces of co-substituted HA was not as high as that of the cells grown on the HA surfaces, it is believed that excellent antibacterial properties and good biological activity can be achieved by balancing the dosage of Sr and Ag.

  13. Adhesion of silver/polypyrrole nanocomposite coating to a fluoropolymer substrate

    Science.gov (United States)

    Horváth, Barbara; Kawakita, Jin; Chikyow, Toyohiro

    2016-10-01

    This paper describes the adhesive interface between a conducting polymer/metal composite and a polytetrafluoroethylene (PTFE) substrate. Strong adhesion was observed from using a Ag/polypyrrole (Ag/PPy) composite on a fluoropolymer substrate, which in most cases has a very low adhesion to different materials. To clarify the adhesion mechanism between the Ag/PPy composite and the PTFE substrate, the interfacial structure was studied by the use of transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS). Our results show that Ag/PPy composite is absorbed inside the nano-sized pores of PTFE and the composite mechanically interlocks after solidifying, which causes the nanocomposite to stick strongly to the substrate. The use of Ag/PPy coating could be a novel technique for developing electrodes, antennae or other high performance applications as this metal/conductive polymer composite has excellent adhesion properties on various plastics.

  14. Morphology Effect of Silver Nanostructures on the Performance of a P3HT:Graphene:AgNs-Based Active Layer Obtained via Dip Coating

    Directory of Open Access Journals (Sweden)

    Alí Gómez-Acosta

    2016-01-01

    Full Text Available We report the effect of the use of different silver nanostructures (AgNs layers deposited via dip coating onto a poly(3-hexylthiophene (P3HT and solution processable functionalized graphene (SPFGraphene composite film intended to be used as active layer in BHJ devices. SPFGraphene was added to P3HT in a ratio of 1.5 wt%. The best results were achieved when a layer of silver nano-pseudospheres (AgNPSs obtained after 10 immersion cycles was used as coating; in this case the highest light trapping and efficiency percent (η=0.23% were achieved. This means an increase of ~11.3% in comparison with the efficiency of the noncoated P3HT:SPFGraphene composite. Results also indicate that graphene was successfully functionalized in order to obtain appropriate dispersion in P3HT and that such conjugated polymer remained unaltered after the addition of SPFGraphene. Finally, it can be concluded that the electrical properties of the as-synthesized films are dependent on the shape and concentration of the AgNs deposited via dip coating.

  15. Effect of phosphate buffer on aggregation kinetics of citrate-coated silver nanoparticles induced by monovalent and divalent electrolytes.

    Science.gov (United States)

    Afshinnia, K; Baalousha, M

    2017-03-01

    The attachment efficiency (α) is an important parameter that can be used to characterize nanoparticle (NPs) aggregation behavior and has been a topic of discussion of several papers in the past few years. The importance of α is because it is one of the key parameters that can be used to model NP environmental fate and behavior. This study uses UV-vis and laser Doppler electrophoresis to monitor the aggregation behavior of citrate-coated silver nanoparticles (cit-AgNPs) induced by Na(+) and Ca(2+) as counter ions in the presence and absence of Suwannee River fulvic acid (SRFA) as a surrogate of natural organic matter and different concentrations of phosphate buffer (0-1mM). Results demonstrate that phosphate buffer, which serves to maintain pH nearly constant over the course of a reaction, is an important determinant of NP aggregation behavior. Increasing phosphate buffer concentration results in a decrease in the critical coagulation concentrations (CCC) of cit-AgNPs to lower counter ion concentration and an increase of α at the same counter ion concentration, both in the absence and presence of SRFA. SRFA stabilizes AgNPs and increases the CCC to higher counter ion concentrations. The outcome of this study can be used to rationalize the variation in α and CCC values reported in the literature for NPs with similar physicochemical properties, where different α and CCC values are reported when different types of buffers and buffer concentrations are used in different studies. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Effects of citrate-coated silver nanoparticles on interactions between soil bacteria and the major crop plant Zea mays

    Science.gov (United States)

    Doody, Michael; Bais, Harsh; Jin, Yan

    2014-05-01

    The increasing use of silver nanoparticles (AgNPs) in commercial antimicrobial products presents an opportunity for increased environmental exposures. While the behavior of AgNPs in surface waters is becoming increasingly understood, little research has been conducted on the effects of these, or any nanoparticles, on soil-dwelling bacteria and major crop plants. Because of the importance of soil bacteria to the overall health of natural and agricultural soils, it is necessary to better understand how AgNPs interact with common bacterial species such as Bacillus subtilis and Escherichia coli. It is further necessary to quantify the effect of AgNPs on major crop plants, including Zea mays, a staple crop for much of the world. Finally, research is needed on how complex plant-microbe interactions that originate in the rhizosphere may be disrupted by AgNPs. Our preliminary data show highly statistically significant growth inhibition near 30% for both species of bacteria exposed to 1.0 mg L-1 citrate-coated AgNPs (c-AgNPs). Growth curves compiled from absorbance data show a similar dose-response for both species. Treatment with aqueous Ag as AgNO3 slightly inhibits E. coli (90 ± 5 %), but enhances growth of B. subtilis to 127 ± 23% of control. These results indicate that toxicity may be related to specific nano-scale properties of the c-AgNPs. On-going experiments measure potential growth inhibition, root development and morphology of Z. mays exposed to c-AgNPs, and resulting changes in plant-microbe interactions.

  17. Effects on cytotoxicity and antibacterial properties of the incorporations of silver nanoparticles into the surface coating of dental alloys*

    Science.gov (United States)

    Shen, Xiao-ting; Zhang, Yan-zhen; Xiao, Fang; Zhu, Jing; Zheng, Xiao-dong

    2017-01-01

    The aim of this study was to research the changes in cytotoxicity and antibacterial properties after silver nanoparticles (AgNPs) were incorporated into the surface coating of dental alloys. AgNPs were attached to cobalt chromium alloys and pure titanium using a hydrothermal method, according to the reaction: AgNO3+NaBH4→ Ag+1/2H2+1/2B2H6+NaNO3. A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay was used to evaluate the cytotoxicity of the alloys when in contact with osteogenic precursor cells (MC3T3-E1) from mice and mesenchymal stem cells (BMSC) from rats. The antibacterial properties of dental alloys incorporating three different concentrations (10, 4, and 2 μmol/L) of AgNPs were tested on Staphylococcus aureus (SA) and Streptococcus mutans (MS). High cytotoxicity values were observed for all dental alloys that contained 0% of AgNPs (the control groups). The incorporation of AgNPs reduced cytotoxicity values. No significant difference was observed for antibacterial performance when comparing dental alloys containing AgNPs to the respective control groups. The results demonstrated that the cobalt chromium alloys and pure titanium all had cytotoxicity to MC3T3-E1 and BMSC and that the incorporation of AgNPs could reduce this cytotoxicity. The concentrations of AgNPs adopted in this study were found to have no antibacterial action against SA or MS. PMID:28681586

  18. A novel and greener approach for shape controlled synthesis of gold and gold-silver core shell nanostructure and their application in optical coatings.

    Science.gov (United States)

    Sinha, Tanur; Ahmaruzzaman, M

    2015-06-15

    Green and facile synthetic methods have gained marvellous fame for the production of polyhedral, anisotropic and spherical gold, and gold-silver bimetallic nanostructures. The useful pivotal characteristics of a green procedure are the usage of environment benign solvent medium, reducing and stabilising agents, and shorter reaction time. We describe here a novel, and greener method for the production of gold and gold-silver core shell nanostructures using aqueous fish scales extract of the Labeo rohita. The effect of various reaction parameters, such as temperature and concentration for the synthesis of the nanostructures were studied. Results indicated that triangular and decahedron gold nanostructures were formed at a lower temperature (40°C) and concentration (10%). While, icosahedral and spherical gold nanostructures were produced at a comparatively higher temperature (100°C) and concentration (40%). The study also revealed that the core-shell bimetallic nanostructures with different morphologies (spherical and oval-shape) were formed at different ratios of chloroaurate and silver nitrate solution. Thus, the present study indicated a simple shape controlled synthesis of gold and gold silver core-shell nanostructures. The synthesised gold nanotriangles were coated over the glass substrate and found to be highly efficient in absorbing infra-red radiations for potential architectural applications. Therefore, the study demonstrated the facile usage of gold nanotriangles for optical coatings. The present strategy depicted the dual functional ability of the fish scale extract as reducing and stabilising agents. This strategy also eliminates the usage of hazardous chemicals, toxic solvents and harsh reducing and stabilizing agents.

  19. Adhesion of silver/polypyrrole nanocomposite coating to a fluoropolymer substrate

    Energy Technology Data Exchange (ETDEWEB)

    Horváth, Barbara; Kawakita, Jin, E-mail: KAWAKITA.Jin@nims.go.jp; Chikyow, Toyohiro

    2016-10-30

    Highlights: • Interfacial structure between Ag/polypyrrole (PPy) nanocomposite and PTFE was revealed. • PPy enters into PTFE substrate as a dispersion with up to 12 nm size Ag nanoparticles. • The nanocomposite is absorbed by PTFE substrate up to 1–2 μm deep. • Ag/PPy interlocks mechanically with PTFE causing strong adhesion. - Abstract: This paper describes the adhesive interface between a conducting polymer/metal composite and a polytetrafluoroethylene (PTFE) substrate. Strong adhesion was observed from using a Ag/polypyrrole (Ag/PPy) composite on a fluoropolymer substrate, which in most cases has a very low adhesion to different materials. To clarify the adhesion mechanism between the Ag/PPy composite and the PTFE substrate, the interfacial structure was studied by the use of transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS). Our results show that Ag/PPy composite is absorbed inside the nano-sized pores of PTFE and the composite mechanically interlocks after solidifying, which causes the nanocomposite to stick strongly to the substrate. The use of Ag/PPy coating could be a novel technique for developing electrodes, antennae or other high performance applications as this metal/conductive polymer composite has excellent adhesion properties on various plastics.

  20. Citrate coated silver nanoparticles change heavy metal toxicities and bioaccumulation of Daphnia magna.

    Science.gov (United States)

    Kim, Injeong; Lee, Byung-Tae; Kim, Hyun-A; Kim, Kyoung-Woong; Kim, Sang Don; Hwang, Yu-Sik

    2016-01-01

    Citrate-coated AgNPs (c-AgNPs) have negatively charged surfaces and their surface interactions with heavy metals can affect metal toxicity in aquatic environments. This study used Daphnia magna to compare the acute toxicities and bioaccumulation of As(V), Cd, and Cu when they interact with c-AgNPs. The 24-h acute toxicities of As(V) and Cu were not affected by the addition of c-AgNPs, while bioaccumulation significantly decreased in the presence of c-AgNPs. In contrast, both the 24-h acute toxicity and bioaccumulation of Cd increased in the presence of c-AgNPs. These toxicity and bioaccumulation trends can be attributed to the interactions between the AgNP surface and the heavy metals. As(V) and c-AgNPs compete by negative charge, decreasing As(V) toxicity. Copper adheres readily to c-AgNP citrate, decreasing Cu bioavailability, and thus reducing Cu toxicity and bioaccumulation. Citrate complexes with divalent cations such as Ca and Mg reduce the competition between divalent cations and Cd on biotic ligand, increasing toxicity and bioaccumulation of Cd. This study shows that surface properties determine the effect of c-AgNPs on heavy metal toxicities and bioaccumulations; hence, further studies on the effect of nanoparticle by it surface properties are warranted.

  1. Study of Nano-silver Waterborne Antibacterial Wood Coatings%纳米银水性抗菌木器涂料的研制

    Institute of Scientific and Technical Information of China (English)

    张然; 梁亮; 宛焱; 胡龙

    2015-01-01

    This paper discusses the stable nano-silver colloid with nano silica sol as carrier and glucose as reductant which has characteristics in structure and particle size of the sol.This synthesizing method uses thermal-UV dual curing emulsion as film-forming resin,nano-silver sol as antibacterial agents,and the design of waterborne antibacterial coatings modified by nano-silver.It also explores the effect of nano-sil-ver sol in various mass fractions on antibacterial performance and formaldehyde degradation rate of water-borne wood coatings.The results show when mass fraction of nano-silver sol is 10%,the nano-silver anti-bacterial waterborne wood coatings have satisfactory performance with over 90%antibacterial rate against Escherichia coli and staphylococcus aureus.And after 48 h daylight the volatility of formaldehyde will reach 70%.%以纳米硅溶胶为载体,葡萄糖为还原剂制备出稳定的纳米银溶胶,并对银溶胶的结构和粒径进行表征.选择热-紫外光双重固化乳液作为成膜树脂,以纳米银溶胶作为纳米抗菌剂,设计出纳米银改性水性木器涂料,讨论了不同质量分数的纳米银溶胶对漆膜抗菌性能和降解甲醛效果的影响.结果表明:当纳米银溶胶的质量分数为10%时,该水性抗菌木器涂料的漆膜性能优良,对大肠杆菌和金黄色葡萄球菌的灭菌率达到90%以上,在自然光下处理48 h后对甲醛的去除率可达70%.

  2. Enhanced actuation in functionalized carbon nanotube–Nafion composites

    KAUST Repository

    Lian, Huiqin

    2011-08-01

    The fabrication and electromechanical performance of functionalized carbon nanotube (FCNT)-Nafion composite actuators were studied. The CNTs were modified successfully with polyethylene glycol (PEG), as verified by thermogravimetric analysis (TGA) and Fourier transform infrared (FT-IR) spectroscopy. Scanning electron microscopy (SEM) images show that the FCNTs are homogeneously dispersed in the Nafion matrix. The properties of FCNT-Nafion composites in terms of water uptake, ion exchange capacity, proton conductivity, dynamic mechanical properties, and actuation behavior were evaluated. The results show that the sample with 0.5 wt% FCNT exhibits the best overall behavior. Its storage modulus is 2.4 times higher than that of Nafion. In addition, the maximum generated strain and the blocking force for the same sample are 2 and 2.4 times higher compared to the neat Nafion actuator, respectively. © 2011 Elsevier B.V.

  3. Examination of tapered plastic multimode fiber-based sensor performance with silver coating for different concentrations of calcium hypochlorite by soft computing methodologies--a comparative study.

    Science.gov (United States)

    Zakaria, Rozalina; Sheng, Ong Yong; Wern, Kam; Shamshirband, Shahaboddin; Wahab, Ainuddin Wahid Abdul; Petković, Dalibor; Saboohi, Hadi

    2014-05-01

    A soft methodology study has been applied on tapered plastic multimode sensors. This study basically used tapered plastic multimode fiber [polymethyl methacrylate (PMMA)] optics as a sensor. The tapered PMMA fiber was fabricated using an etching method involving deionized water and acetone to achieve a waist diameter and length of 0.45 and 10 mm, respectively. In addition, a tapered PMMA probe, which was coated by silver film, was fabricated and demonstrated using a calcium hypochlorite (G70) solution. The working mechanism of such a device is based on the observation increment in the transmission of the sensor that is immersed in solutions at high concentrations. As the concentration was varied from 0 to 6 ppm, the output voltage of the sensor increased linearly. The silver film coating increased the sensitivity of the proposed sensor because of the effective cladding refractive index, which increases with the coating and thus allows more light to be transmitted from the tapered fiber. In this study, the polynomial and radial basis function (RBF) were applied as the kernel function of the support vector regression (SVR) to estimate and predict the output voltage response of the sensors with and without silver film according to experimental tests. Instead of minimizing the observed training error, SVR_poly and SVR_rbf were used in an attempt to minimize the generalization error bound so as to achieve generalized performance. An adaptive neuro-fuzzy interference system (ANFIS) approach was also investigated for comparison. The experimental results showed that improvements in the predictive accuracy and capacity for generalization can be achieved by the SVR_poly approach in comparison to the SVR_rbf methodology. The same testing errors were found for the SVR_poly approach and the ANFIS approach.

  4. In vitro and in vivo evaluation of biologically synthesized silver nanoparticles for topical applications: effect of surface coating and loading into hydrogels

    Directory of Open Access Journals (Sweden)

    Mekkawy AI

    2017-01-01

    Full Text Available Aml I Mekkawy,1 Mohamed A El-Mokhtar,2 Nivien A Nafady,3 Naeima Yousef,3 Mostafa A Hamad,4 Sohair M El-Shanawany,5 Ehsan H Ibrahim,5 Mahmoud Elsabahy5–8 1Department of Pharmaceutics and Clinical Pharmacy, Faculty of Pharmacy, Sohag University, Sohag, 2Department of Microbiology and Immunology, Faculty of Medicine, 3Department of Botany and Microbiology, Faculty of Science, 4Department of Surgery, Faculty of Medicine, 5Department of Pharmaceutics, Faculty of Pharmacy, 6Assiut International Center of Nanomedicine, Al-Rajhi Liver Hospital, Assiut University, Assiut, Egypt; 7Laboratory for Synthetic-Biologic Interactions, Department of Chemistry, Texas A&M University, College Station, TX, USA; 8Misr University for Science and Technology, 6th of October, Egypt Abstract: In the present study, silver nanoparticles (AgNPs were synthesized via biological reduction of silver nitrate using extract of the fungus Fusarium verticillioides (green chemistry principle. The synthesized nanoparticles were spherical and homogenous in size. AgNPs were coated with polyethylene glycol (PEG 6000, sodium dodecyl sulfate (SDS, and β-cyclodextrin (β-CD. The averaged diameters of AgNPs were 19.2±3.6, 13±4, 14±4.4, and 15.7±4.8 nm, for PEG-, SDS-, and ß-CD-coated and uncoated AgNPs, respectively. PEG-coated AgNPs showed greater stability as indicated by a decreased sedimentation rate of particles in their water dispersions. The antibacterial activities of different AgNPs dispersions were investigated against Gram-positive bacteria (methicillin-sensitive and methicillin-resistant Staphylococcus aureus and Gram-negative bacteria (Escherichia coli by determination of the minimum inhibitory concentrations (MICs and minimum bactericidal concentrations (MBCs. MIC and MBC values were in the range of 0.93–7.5 and 3.75–15 µg/mL, respectively, which were superior to the reported values in literature. AgNPs-loaded hydrogels were prepared from the coated

  5. Silver Doped TiO2 Nanostructure Composite Photocatalyst Film Synthesized by Sol-Gel Spin and Dip Coating Technique on Glass

    OpenAIRE

    Mojtaba Nasr-Esfahani; Mohammad Hossein Habibi

    2008-01-01

    New composite films (P25SGF-MC-Ag, MPC500SGF-MC-Ag, and ANPSGF-MC-Ag) have been synthesized by a modified sol-gel method using different particle sizes of TiO2 powder and silver addition. Nanostructure TiO2/Ag composite thin films were prepared by a sol-gel spin and dip coating technique. while, by introducing methyl cellulose (MC) porous, TiO2/Ag films were obtained after calcining at a temperature of 500°C. The as-prepared TiO2 and TiO2/Ag films were characterized by X-ray diffractometry, a...

  6. Inactivation of microbial infectiousness by silver nanoparticles-coated condom: a new approach to inhibit HIV- and HSV-transmitted infection

    Directory of Open Access Journals (Sweden)

    Mohammed Fayaz A

    2012-09-01

    Full Text Available A Mohammed Fayaz,1,* Zhujun Ao,1,3,* Morkattu Girilal,2 Liyu Chen,3,4 Xianzhong Xiao,4 PT Kalaichelvan,2 Xiaojian Yao1,31Laboratory of Molecular Human Retrovirology, Department of Medical Microbiology, Faculty of Medicine, University of Manitoba, Winnipeg, MB, Canada; 2CAS in Botany, University of Madras, Guindy Campus, Chennai, Tamil Nadu, India; 3Department of Microbiology, 4School of Basic Medical Sciences, Central South University, Changsha, Hunan, People’s Republic of China*Both authors contributed equally to this workAbstract: Recent research suggests that today’s condoms are only 85% effective in preventing human immunodeficiency virus (HIV and other sexually transmitted diseases. In response, there has been a push to develop more effective ways of decreasing the spread of the disease. The new nanotechnology-based condom holds the promise of being more potent than the first-generation products. The preliminary goal of this study was to develop a silver nanoparticles (Ag-NPs-coated polyurethane condom (PUC and to investigate its antimicrobial potential including the inactivation of HIV and herpes simplex virus (HSV infectiousness. The Ag-NPs-coated PUC was characterized by using ultraviolet-visible spectrophotometry, Fourier transform-infrared spectroscopy, high-resolution scanning electron microscopy, and energy-dispersive analysis of X-ray spectroscopy. Nanoparticles were stable on the PUC and not washed away by water. Morphology of the PUC was retained after coating. The NP binding is due to its interaction with the nitrogen atom of the PUC. No significant toxic effects was observed when human HeLa cells, 293T and C8166 T cells were contacted to Ag-NPs-coated PUC for three hours. Interestingly, our results demonstrated that the contact of the Ag-NPs-coated PUC with HIV-1 and HSV-1/2 was able to efficiently inactivate their infectiousness. In an attempt to elucidate the antiviral action of the Ag-NPs, we have demonstrated that the

  7. 载银硅灰石涂层对变形链球菌的抑制%Inhibition effect of silver ion-loaded wollastonite coating on streptococcus mutans

    Institute of Scientific and Technical Information of China (English)

    贾莹; 刘焱; 秦波; 王金生

    2012-01-01

    背景:涂层材料本身无抗菌性,带有涂层的植入物在植入体内后也有发生感染的可能.目的:体外实验评价载银硅灰石涂层对变形链球菌的抑制作用.方法:用纸片扩散法测定载银硅灰石涂层材料的抑菌环大小,从而评价材料的抑菌性能优劣.结果与结论:随着硝酸银浓度的提高,涂层载银量增加;5%载银硅石灰组抑菌环持续40 d 以上,其最大直径显著大于1%载银硅石灰组抑菌环最大直径及未载银原始硅灰石涂层的抑菌环最大直径(P均<0.01).结果提示,载银硅石灰涂层能缓慢释放出具有抗菌作用的Ag+,从而具有一定的抑菌性.通过加入不同初始浓度的Ag+溶液,可以在一定范围内调节载银硅石灰涂层的抑菌效率和持续时间.%BACKGROUND: Coating material has no antibacterial. Implants containing coatings may result in infection after implantation in vivo. OBJECTIVE: To evaluate the inhibition effect of silver ion-loaded wollastonite coating on streptococcus mutans in vitro. METHODS: The bacteriostatic annulus of silver ion-loaded wollastonite coating were measured using disc diffusion method in order to evaluate the antibacterial properties of the material. RESULTS AND CONCLUSION: With the increase of the concentration of nitric acid silver, the silver ion in the coatings was increased. The bacteriostatic annulus of the 5% silver ion-loaded wollastonite group sustained for over 40 days, and the maximum diameter was bigger than those of the 1% silver ion-loaded wollastonite group and the none silver ion-loaded wollastonite group (P < 0.01). It is indicated that the silver ion-loaded wollastonite coating can slowly release Ag+ which can inhibit bacteria. The bacteriostatic efficiency of silver ion-loaded wollastonite coating and its duration time can be regulated in some degree by adding Ag+ solution of different initial concentrations into it.

  8. Super-hydrophobic Silver-Doped TiO2 @ Polycarbonate Coatings Created on Various Material Substrates with Visible-Light Photocatalysis for Self-Cleaning Contaminant Degradation

    Science.gov (United States)

    Li, Zhengjian; Sun, Zongzhao; Duan, Zhiqiang; Li, Rui; Yang, Yanli; Wang, Jingyi; Lv, Xiaoxia; Qi, Wei; Wang, Hua

    2017-01-01

    In the present work, a facile and efficient fabrication method has been developed for creating super-hydrophobic coatings of silver-doped TiO2@polycarbonate (TiO2 (Ag)@PC) on the substrates of different materials with photocatalytic self-cleaning performances simply by the “dipping and drying” process. The substrates were first patterned with glue and then deposited with the dopamine-capped TiO2 (Ag)@PC (DA-TiO2 (Ag)@PC) nanocomposites, followed by the further etching with dimethylbenzene. The so prepared super-hydrophobic E-DA-TiO2(Ag)@PC coatings could present the lotus leaf-like porous architectures, high adhesion stability, and especially the visible-light photocatalysis for organic contaminant degradation, thus promising the wide outdoor and indoor applications like water proofing, metal erosion protection, and surface self-cleaning. PMID:28218285

  9. Super-hydrophobic Silver-Doped TiO2 @ Polycarbonate Coatings Created on Various Material Substrates with Visible-Light Photocatalysis for Self-Cleaning Contaminant Degradation

    Science.gov (United States)

    Li, Zhengjian; Sun, Zongzhao; Duan, Zhiqiang; Li, Rui; Yang, Yanli; Wang, Jingyi; Lv, Xiaoxia; Qi, Wei; Wang, Hua

    2017-02-01

    In the present work, a facile and efficient fabrication method has been developed for creating super-hydrophobic coatings of silver-doped TiO2@polycarbonate (TiO2 (Ag)@PC) on the substrates of different materials with photocatalytic self-cleaning performances simply by the “dipping and drying” process. The substrates were first patterned with glue and then deposited with the dopamine-capped TiO2 (Ag)@PC (DA-TiO2 (Ag)@PC) nanocomposites, followed by the further etching with dimethylbenzene. The so prepared super-hydrophobic E-DA-TiO2(Ag)@PC coatings could present the lotus leaf-like porous architectures, high adhesion stability, and especially the visible-light photocatalysis for organic contaminant degradation, thus promising the wide outdoor and indoor applications like water proofing, metal erosion protection, and surface self-cleaning.

  10. New type of protective hybrid and nanocomposite hybrid coatings containing silver and copper with an excellent antibacterial effect especially against MRSA

    Energy Technology Data Exchange (ETDEWEB)

    Slamborova, Irena [Centre for Nanomaterials, Advanced Technologies and Innovations, Studentska 1402/2, 461 17 Liberec 1 (Czech Republic); Zajicova, Veronika, E-mail: veronika.zajicova@tul.cz [Centre for Nanomaterials, Advanced Technologies and Innovations, Studentska 1402/2, 461 17 Liberec 1 (Czech Republic); Karpiskova, Jana [Institute of Novel Technologies and Applied Informatics, Faculty of Mechatronics, Informatics and Interdisciplinary Studies, Technical University of Liberec, Studentska 2, 461 17 Liberec 1 (Czech Republic); Exnar, Petr; Stibor, Ivan [Centre for Nanomaterials, Advanced Technologies and Innovations, Studentska 1402/2, 461 17 Liberec 1 (Czech Republic)

    2013-01-01

    Epidemics spread many types of pathogenic bacterial strains, especially strains of MRSA (Methicillin-resistant Staphylococcus aureus), which are being increasingly reported in many geographical areas [1]. This is becoming to be a serious global problem, particularly in hospitals. Not only are antibiotics proving to be increasingly ineffective but also the bacteria responsible for more than 70% of hospital-acquired bacterial infections are resistant to at least one of the drugs commonly used to treat them. In this study, hybrid coating A1 and nanocomposite hybrid coating A2 based on TMSPM (3-(trimethoxysilyl)propyl methacrylate, MMA (methyl methacrylate), TEOS (tetraethyl orthosilicate) and IPTI (titanium isopropoxide) containing silver and copper ions with or without nanoparticles of titanium dioxide were prepared by the sol-gel method. They were deposited on glass, poly(methyl methacrylate) and cotton using dip-coating or spin-coating, and then cured at 150 Degree-Sign C for 3 h or, in the case of poly(methyl methacrylate), at 100 Degree-Sign C for 4.5 h. The morphology and microstructure of these hybrid coatings were examined by SEM. The abrasion resistance was tested using a washability tester and found to depend heavily on the curing temperature. Seven types of bacterial strains were used to determine the profile of antibacterial activity, namely Escherichia coli, Staphylococcus aureus, Methicillin-resistant Staphylococcus aureus - MRSA (CCM 4223), MRSA-2 (CCM 7112), Acinetobacter baumanii, Pseudomonas aeruginosa, and Proteus vulgaris (according to ALE-G18, CSNI). All the samples were tested by irradiating with either a UV-A or a daylight fluorescent lamp. All types of hybrid coating A1 and nanocomposite hybrid coating A2 were found to possess an excellent antibacterial effect, including against the pathogenic bacterial strains of MRSA, which present a dangerous threat on a global scale.

  11. Biological responses of human gingival fibroblasts (HGFs in an innovative co-culture model with Streptococcus mitis to thermosets coated with a silver polysaccharide antimicrobial system.

    Directory of Open Access Journals (Sweden)

    Silvia Sancilio

    Full Text Available This study sought to evaluate the in vitro biological response of human gingival fibroblasts (HGFs co-coltured with Streptococcus mitis to bisphenol A glycidylmethacrylate/triethylene glycol dimethacrylate (BisGMA/TEGDMA thermosets coated with Chitlac-nAg, a nanocomposite system with antimicrobial properties. To avoid bacterial adhesion to dental devices and to reduce cytotoxicity against eukaryotic cells, we coated BisGMA/TEGDMA methacrylic thermosets with a new material, Chitlac-nAg, formed by stabilizing silver nanoparticles, which have well-known antimicrobial properties, with a polyelectrolyte solution containing Chitlac. Cytotoxicity, cell morphology, cell migration and inflammatory interleukine-6 (IL-6 and prostaglandin E2 (PGE2 secretion were evaluated. Our results showed that the cytotoxicity exerted on HGFs by our nanocomposite material was absent in our co-culture model, where fibroblasts are able to adhere and migrate. After 24 h thermosets coated with Chitlac as well as those coated with Chitlac-nAg exerted a minimal cytotoxic effect on HGFs, while after 48 h LDH release rises up 20%. Moreover the presence of S. mitis reduced this release in a greater amount with Chitlac-nAg coated thermosets. The secretion of IL-6 was significant in both Chitlac and Chitlac-nAg coated thermosets, but PGE2 production was minimal, suggesting that the IL-6 production was not related to an inflammatory response. Co-culture and the addiction of saliva did not influence IL-6 and PGE2 secretion. Data obtained in the present work suggest that Chitlac n-Ag coated thermosets could significantly improve the success rates of restorative dentistry, since they limit bacterial adhesion and are not toxic to HGFs.

  12. Bactericidal activities of woven cotton and nonwoven polypropylene fabrics coated with hydroxyapatite-binding silver/titanium dioxide ceramic nanocomposite "Earth-plus"

    Directory of Open Access Journals (Sweden)

    Kasuga E

    2011-09-01

    Full Text Available Eriko Kasuga1,2, Yoshiyuki Kawakami2,3, Takehisa Matsumoto1, Eiko Hidaka1, Kozue Oana2, Naoko Ogiwara1, Dai Yamaki4, Tsukasa Sakurada4, Takayuki Honda1,51Department of Laboratory Medicine, Shinshu University Hospital, 2Division of Infection Control and Microbiological Regulation, Department of Health and Medical Sciences, Shinshu University Graduate School of Medicine, 3Division of Clinical Microbiology, Department of Biomedical Laboratory Sciences, School of Health Sciences, Shinshu University School of Medicine, 4Shinshu Ceramics Co Ltd, Kiso, Nagano, Japan; 5Department of Laboratory Medicine, Shinshu University School of Medicine, Matsumoto, JapanBackground: Bacteria from the hospital environment, including linens and curtains, are often responsible for hospital-associated infections. The aim of the present study was to evaluate the bactericidal effects of fabrics coated with the hydroxyapatite-binding silver/titanium dioxide ceramic nanocomposite "Earth-plus".Methods: Bactericidal activities of woven and nonwoven fabrics coated with Earth-plus were investigated by the time-kill curve method using nine bacterial strains, including three Staphylococcus aureus, three Escherichia coli, and three Pseudomonas aeruginosa strains.Results: The numbers of viable S. aureus and E. coli cells on both fabrics coated with Earth-plus decreased to below 2 log10 colony-forming units/mL in six hours and reached the detection limit in 18 hours. Viable cell counts of P. aeruginosa on both fabrics coated with Earth-plus could not be detected after 3–6 hours. Viable cells on woven fabrics showed a more rapid decline than those on nonwoven fabrics. Bacterial cell counts of the nine strains on fabrics without Earth-plus failed to decrease even after 18 hours.Conclusion: Woven cotton and nonwoven polypropylene fabrics were shown to have excellent antibacterial potential. The woven fabric was more bactericidal than the nonwoven fabric.Keywords: hydroxyapatite

  13. Assessment of the effectiveness of silver-coated dressing, chlorhexidine acetate (0.5%), citric acid (3%), and silver sulfadiazine (1%) for topical antibacterial effects against the multi-drug resistant Pseudomonas aeruginosa infecting full-skin thickness burn wounds on rats.

    Science.gov (United States)

    Yabanoglu, Hakan; Basaran, Ozgur; Aydogan, Cem; Azap, Ozlem Kurt; Karakayali, Feza; Moray, Gokhan

    2013-01-01

    The aim of this study was to compare the effects of four different topical antimicrobial dressings on a multi-drug resistant Pseudomonas aeruginosa contaminated full-thickness burn wound rat model. A total of 40 adult male Wistar albino rats were used. The control group (group 1), silver sulfadiazine (1%) group 2, chlorhexidine acetate (0.5%) group 3, citric acid (3%) group 4, and silver-coated dressing group 5 were compared to assess the antibacterial effects of a daily application to a 30% full-skin thickness burn wound seeded 10 minutes earlier with 10(8) CFU (colony forming unit)/0.5 mL of a multi-drug resistant Pseudomonas aeruginosa strain. Five groups (1 control group and 4 treatment groups) were compared. The administration of third-degree burns to all rats was confirmed based on histopathologic data. The tissue cultures from groups 2 and 5 exhibited significant differences compared to those of the other 3 groups, whereas no significant differences were observed between groups 1, 3, and 4. The effectiveness of the treatments was as follows: 1% silver sulfadiazine > silver-coated dressing > 3% citric acid > 0.5% chlorhexidine acetate > control group. Our results supported the efficacy of topical therapy by silver sulfadiazine and silver-coated dressing on infections caused by multi-drug resistant Pseudomonas spp.

  14. Wetting and absorption of water drops on Nafion films.

    Science.gov (United States)

    Goswami, Sharonmoyee; Klaus, Shannon; Benziger, Jay

    2008-08-19

    Water drops on Nafion films caused the surface to switch from being hydrophobic to being hydrophilic. Contact angle hysteresis of >70 degrees between advancing and receding values were obtained by the Wilhelmy plate technique. Sessile drop measurements were consistent with the advancing contact angle; the sessile drop contact angle was 108 degrees . Water drop adhesion, as measured by the detachment angle on an inclined plane, showed much stronger water adhesion on Nafion than Teflon. Sessile water and methanol drops caused dry Nafion films to deflect. The flexure went through a maximum with time. Flexure increased with contact area of the drop, but was insensitive to the film thickness. Methanol drops spread more on Nafion and caused larger film flexure than water. The results suggest that the Nafion surface was initially hydrophobic but water and methanol drops caused hydrophilic sulfonic acid domains to be drawn to the Nafion surface. Local swelling of the film beneath the water drop caused the film to buckle. The maximum flexure is suggested to result from motion of a water swelling front through the Nafion film.

  15. Two-component spin-coated Ag/CNT composite films based on a silver heterogeneous nucleation mechanism adhesion-enhanced by mechanical interlocking and chemical grafting

    Science.gov (United States)

    Zhang, Yang; Kang, Zhixin; Bessho, Takeshi

    2017-03-01

    In this paper, a new method for the synthesis of silver carbon nanotube (Ag/CNT) composite films as conductive connection units for flexible electronic devices is presented. This method is about a two-component solution process by spin coating with an after-treatment annealing process. In this method, multi-walled carbon nanotubes (MWCNTs) act as the core of silver heterogeneous nucleation, which can be observed and analyzed by a field-emission scanning electron microscope. With the effects of mechanical interlocking, chemical grafting, and annealing, the interfacial adhesive strength between films and PET sheets was enhanced to 12 N cm-1. The tensile strength of the Ag/CNT composite films was observed to increase by 38% by adding 5 g l-1 MWCNTs. In the four-probe method, the resistivity of Ag/CNT-5 declined by 78.2% compared with pristine Ag films. The anti-fatigue performance of the Ag/CNT composite films was monitored by cyclic bending deformation and the results revealed that the growth rate of electrical resistance during the deformation was obviously retarded. As for industrial application, this method provides an efficient low-cost way to prepare Ag/CNT composite films and can be further applied to other coating systems.

  16. Antibacterial efficacy of advanced silver-amorphous carbon coatings deposited using the pulsed dual cathodic arc technique

    Energy Technology Data Exchange (ETDEWEB)

    Endrino, J L; Anders, A; Albella, J M; Horton, J A; Horton, T H; Ayyalasomayajula, P R; Allen, M, E-mail: jlendrino@icmm.csic.es

    2010-11-01

    Amorphous carbon (a-C) also referred as diamond-like carbon (DLC) films are well known to be a biocompatible material with good chemical in ertness; this makes it a strong candidate to be used as a matrix that embeds metallic elements with an antimicrobial effect. We have deposited as et of a-C:Ag films using a dual-cathode pulsed filtered cathodic arc source, the arc pulse frequency of the silver and graphite cathodes was controlled in order to obtain samples with various silver contents. In this study, we show the deposition of silver and carbon ions using this technique and analyze the advantages of incorporating silver into a-C by studying the antimicrobial properties against staphylococcus of samples deposited on Ti{sub 6}Al{sub 4}V coupons and evaluated using 24-well tissue culture plates.

  17. Photocatalytic and biocidal activities of novel coating systems of mesoporous and dense TiO{sub 2}-anatase containing silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Roldán, María V. [Laboratorio de Materiales Cerámicos, FCEIA-UNR, IFIR-CONICET, Pellegrini 250, Rosario S2000BTP (Argentina); Oña, Paula de [Laboratorio de Microbiología Molecular, FCByF-UNR-CONICET, Suipacha 531, Rosario S2002LRK (Argentina); Castro, Yolanda; Durán, Alicia [Instituto de Cerámica y Vidrio (CSIC), Campus de Cantoblanco, 28049, Madrid (Spain); Faccendini, Pablo; Lagier, Claudia [IQUIR-UNR-CONICET, Suipacha 531, Rosario S2002LRK (Argentina); Grau, Roberto, E-mail: robertograu@fulbrightmail.org [Laboratorio de Microbiología Molecular, FCByF-UNR-CONICET, Suipacha 531, Rosario S2002LRK (Argentina); Pellegri, Nora S., E-mail: pellegri@fceia.unr.edu.ar [Laboratorio de Materiales Cerámicos, FCEIA-UNR, IFIR-CONICET, Pellegrini 250, Rosario S2000BTP (Argentina)

    2014-10-01

    Here we describe the development of novel nanostructured coating systems with improved photocatalytic and antibacterial activities. These systems comprise a layer of SiO{sub 2} followed by a layer of mesoporous or dense TiO{sub 2}-anatase, and doping with silver nanoparticles (Ag NPs). The coatings were synthesized via a sol–gel technique by combining colloidal Ag NPs with TiO{sub 2} and SiO{sub 2} sols. The photocatalytic activity was studied through methyl orange decomposition under UV light. Results showed a great increase of photocatalytic activity by Ag NPs doping. The most active photocatalyst corresponded to the Ag–SiO{sub 2}/TiO{sub 2} mesoporous system, associated with the porosity of the coatings and with the decrease of e–h recombination for the presence of Ag NPs. All the TiO{sub 2} coatings showed a strong bactericidal activity against planktonic forms of Gram-negative (enterohemorrhagic Escherichia coli) and Gram-positive (Listeria monocytogenes) pathogens, as well as a strong germicidal effect against deadly spores of human gas gangrene- and anthrax-producing bacteria (Clostridium perfringens and Bacillus anthracis, respectively). The bactericidal and sporocidal activity was improved by doping the coatings with Ag NPs, even more when nanoparticles were in the outer layer of TiO{sub 2}, because they are more accessible to the environment. The mechanisms responsible for the increase of photocatalytic and bactericidal behaviors related to Ag NP doping were studied by spectroscopic ellipsometry, UV–vis spectroscopy, photoluminescence and anodic stripping voltammetry. It was found that the separation of the electron–hole pair contributed to the enhancement of photocatalysis, whereas the effect of the local electric field reinforcement was probably present. A possible involvement of a decrease of band-gap energy and dispersion by silver nanoparticles is ruled out. bactericidal efficacy was increased by Ag{sup +} ion release. Overall, the results

  18. Carbon nanotubes based nafion composite membranes for fuel cell applications

    CSIR Research Space (South Africa)

    Cele, NP

    2009-01-01

    Full Text Available surface oxidation as well as functionalisation in composite membranes was investigated by focussing on three aspects: thermo-mechanical stability, thermal degradation and proton conductivity. The oCNTs-containing Nafion composite membrane exhibited...

  19. Nafion-based nanocomposite membranes for fuel cells

    CSIR Research Space (South Africa)

    Cele, NP

    2008-11-01

    Full Text Available Nafion nanocomposites were prepared with pure multiwalled carbon nanotubes (PMWCNTs), oxidised MWCNTs (OMWCNTs) and functionalised MWCNTs (FMWCNTs) as fillers, to investigate the effect of multiwalled carbon nanotubes on thermal stability...

  20. Multifunctional Graphene/Platinum/Nafion Hybrids via Ice Templating

    KAUST Repository

    Estevez, Luis

    2011-04-27

    We report the synthesis of multifunctional hybrids in both films and bulk form, combining electrical and ionic conductivity with porosity and catalytic activity. The hybrids are synthesized by a two-step process: (a) ice templation of an aqueous suspension comprised of Nafion, graphite oxide, and chloroplatinic acid to form a microcellular porous network and (b) mild reduction in hydrazine or monosodium citrate which leads to graphene-supported Pt nanoparticles on a Nafion scaffold. © 2011 American Chemical Society.

  1. Aqua-vanadyl ion interaction with Nafion® membranes

    Directory of Open Access Journals (Sweden)

    Vijayakumar eMurugesan

    2015-03-01

    Full Text Available Lack of comprehensive understanding about the interactions between Nafion membrane and battery electrolytes prevents the straightforward tailoring of optimal materials for redox flow battery applications. In this work, we analyzed the interaction between aqua-vanadyl cation and sulfonic sites within the pores of Nafion membranes using combined theoretical and experimental X-ray spectroscopic methods. Molecular level interactions namely solvent share and contact pair mechanisms are discussed based on Vanadium and Sulfur K-edge spectroscopic analysis.

  2. Novel method to produce {sup 109}Cd via proton irradiation of electroplated silver on a gold-coated copper backing

    Energy Technology Data Exchange (ETDEWEB)

    Gholamzadeh, Z.; Sadeghi, M.; Mirzaei, M. [Nuclear Science and Technology Research Institute, Tehran (Iran, Islamic Republic of). Agricultural, Medical and Industrial Research School; Aref, M. [Zanjan Univ. (Iran, Islamic Republic of). Faculty of Physics

    2011-08-15

    Silver electrodeposition on gold layer was carried out by the alkaline plating baths to produce cadmium-109 via {sup nat}Ag(p, n){sup 109}Cd nuclear reaction. Gold was electrodeposited on copper backing in the beginning; the bath content consisted of 17.7 gl{sup -1} KCN, 6.6 gl{sup -1} Au, 6.6 gl{sup -1} K{sub 2}CO{sub 3} and 3.3 gl{sup -1} Na{sub 2}CO{sub 3} while acidity and temperature of the bath adjusted at 10 and 45 C respectively. A DC current density of ca 2.08 mA . cm{sup -2} was used to electroplate gold. A gold layer of 63 {mu}m thickness with suitable morphology was obtained after the electrodeposition. Silver was electrodeposited on the gold layer with 100% efficiency using a cyanide bath. The silver target was irradiated with 15 MeV proton beam and current of 150 {mu}A; the {sup 109}Cd production yield was 2.0 {mu}Ci/{mu}A . h (0.074 MBq/{mu}A . h). The target material was dissolved by 14 M HNO{sub 3}{sup .} Cadmium-109 in the dissolved target solution was separated from silver by evaporation process. Cadmium recovered with more than 88% efficiency involved non-detected silver impurity. (orig.)

  3. Thermal stability of nafion membranes under mechanical stress

    Energy Technology Data Exchange (ETDEWEB)

    Quintilii, M.; Struis, R. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    The feasibility of adequately modified fluoro-ionomer membranes (NAFION{sup R}) is demonstrated for the selective separation of methanol synthesis products from the raw reactor gas at temperatures around 200{sup o}C. For an economically relevant application of this concept on a technical scale the Nafion membranes should be thin ({approx_equal}10 {mu}m) and thermally stable over a long period of time (1-2 years). In cooperation with industry (Methanol Casale SA, Lugano (CH)), we test the thermal stability of Nafion hollow fibers and supported Nafion thin sheet membranes at temperatures between 160 and 200{sup o}C under mechanical stress by applying a gas pressure difference over the membrane surface ({Delta}P{<=} 40 bar). Tests with the hollow fibers revealed that Nafion has visco-elastic properties. Tests with 50 {mu}m thin Nafion sheets supported by a porous metal carrier at 200{sup o}C and {Delta}P=39 bar showed no mechanical defects over a period of 92 days. (author) 5 figs., 4 refs.

  4. Synthesizing A Phase Changing Bistable Electroactive Polymer And Silver Nanoparticles Coated Fabric As A Resistive Heating Element

    Science.gov (United States)

    Ren, Zhi

    that decreases to several MPa at above 70°C after a rigid-to-rubbery transition via glass transition. The rubbery BSEP possesses a stable storage modulus regardless of temperature fluctuations, which is beneficial to stable electrical actuation performances under an electric field. The bimodal structure creates a framework involving both long chain crosslinkers and small molecular crosslinkers. Due to the limited chain extensibility of this bimodal framework, the rubbery BSEP can self-stiffen at modest strains to suppress electromechanical instability, which is responsible for the premature electrical breakdown of the previous BSEP materials in their rubbery states. A BSEP actuator with a braille dot size exhibits steadily increased actuation height with increasing electric field at 70 °C. A stable actuation with a cycle lifetime of over 2000 cycles at a raised dot height of 0.4 mm was demonstrated. A fabrication process for a page-size braille paper using the BSEP has been developed. A selective heating strategy has been investigated based on a 2-cell device to provide a selective actuation strategy of BSEP braille dots. Wearable thermal management strategy has presented itself recently as a new challenge to offer an optimal thermal experience for the occupant as well as to reduce building energy usage for heating, ventilation and air conditioning (HVAC). Joule heating based on silver nanoparticles (AgNPs) coated non-woven fabric can provide a wearable localized heating element.A sheet resistance of <0.3 ohm/square can be achieved for AgNPs-coated polyester fabrics upon thermal annealing. Multistep electroless deposition creates chemical bonding between oxygen groups on the fabrics' surface and AgNPs. As a result, the bonding between the AgNPs layer and the polyester fabrics is strong enough to resist sonication damage. The resistance only increased slightly after an 80minutes of sonication and therefore the AgNPs-polyester fabrics composite are regarded as washable

  5. Development of Antibacterial Plastic Biliary Stent Coated with Nono-Silver%胆管纳米银涂层抗菌塑料支架的研制

    Institute of Scientific and Technical Information of China (English)

    杨杰; 令狐恩强; 王银川

    2011-01-01

    The common complications of the endoprosthesis are occlusion of the stents;and cholangitis. There are many bacterial colonies in the blocked stents. Some studies have proved that the silver in a low concentration has the antimicrobial efficacy.The plastic biliary stents coated with nano-silver were prepared by the chemical redox process with plastic stents as carriers and silver nitrate as material. Then the friction coefficient and elastic modulus of the stents were detected by use of scanning electron microscope(SEM),transmission electron microscopy (TEM)and Energy Dispersive X-ray analysis(EDXA);scanning tunneling microscope(STM). The result shows that the nano-sliver coating is high purity and the nanoparticle is well-distributed;range of size is 5-80nm. Antibacterial plastic biliary stents coated with nano-sliver that its surface is smooth and elasticity is not obvious change.%胆管塑料支架置入胆管时常见的并发症是胆管炎、支架阻塞,可以见到大量的细菌菌落.应用低浓度的银离子对细菌、真菌等微生物具有杀灭作用.通过化学氧化还原法,以胆管塑料支架为载体,硝酸银为原料,在胆管支架内外表面均匀沉积纳米银,研制成功纳米银涂层抗菌塑料胆管支架.通过扫描电镜(SEM )、透射电镜(TEM )、X射线能谱分析(EDXA) 、扫描隧道显微镜(STM )等检测纳米银涂层塑料胆管支架的弹性系数和摩擦系数.结果 表明,制备纳米银涂层纳米颗粒分布均匀、纯度高、纳米颗粒大小约5-80 nm.纳米银涂层抗菌塑料支架表面光滑,弹性较原始支架无明显变化.

  6. The in vivo effect of a porous titanium alloy flange with hydroxyapatite, silver and fibronectin coatings on soft-tissue integration of intraosseous transcutaneous amputation prostheses

    Science.gov (United States)

    Chimutengwende-Gordon, M.; Pendegrass, C.; Blunn, G.

    2017-01-01

    Aims The Intraosseous Transcutaneous Amputation Prosthesis (ITAP) may improve quality of life for amputees by avoiding soft-tissue complications associated with socket prostheses and by improving sensory feedback and function. It relies on the formation of a seal between the soft tissues and the implant and currently has a flange with drilled holes to promote dermal attachment. Despite this, infection remains a significant risk. This study explored alternative strategies to enhance soft-tissue integration. Materials and Methods The effect of ITAP pins with a fully porous titanium alloy flange with interconnected pores on soft-tissue integration was investigated. The flanges were coated with fibronectin-functionalised hydroxyapatite and silver coatings, which have been shown to have an antibacterial effect, while also promoting viable fibroblast growth in vitro. The ITAP pins were implanted along the length of ovine tibias, and histological assessment was undertaken four weeks post-operatively. Results The porous titanium alloy flange reduced epithelial downgrowth and increased soft-tissue integration compared with the current drilled flange. The addition of coatings did not enhance these effects. Conclusion These results indicate that a fully porous titanium alloy flange has the potential to increase the soft-tissue seal around ITAP and reduce susceptibility to infection compared with the current design. Cite this article: Bone Joint J 2017;99-B:393–400. PMID:28249981

  7. The effect of electron and gamma irradiation on the quality of surface and reflection of silver mirror coated by TiO2 and Ta2O5

    Directory of Open Access Journals (Sweden)

    E Khalouie

    2016-02-01

    Full Text Available In this study, the effects of gamma and electron radiation on reflectivity of silver mirrors coated by TiO2 and Ta2O5, in the wavelength range 250 to 1100 (nm has been investigated. The coatings are considered for space applications in LEO orbit at 500 (km from the earth surface for three-year mission in space. Electron and gamma dose absorbed within the three-year are respectively about 7.5 (KGy and 0.4 (KGy in this orbit. To measure the resistance of TiO2, gamma radiation with CO60 irradiation source was applied on the sample in the range from 0.2 to 20 (KGy including dose 400 (Gy at the desired height. At the highest dose, 20 (KGy, radiation effects on both samples were compared with each other. The atomic force microscopy was used to investigate the effect of radiation on the quality of samples surface after radiation, and an spectrophotometer was used to measure the samples reflection before and after radiation. The results showed that in spite of very minor surface changes, and color change of the mirror substrate, its reflection remains unchanged with TiO2 and Ta2O5 coatings.

  8. A spray-coating process for highly conductive silver nanowire networks as the transparent top-electrode for small molecule organic photovoltaics.

    Science.gov (United States)

    Selzer, Franz; Weiss, Nelli; Kneppe, David; Bormann, Ludwig; Sachse, Christoph; Gaponik, Nikolai; Eychmüller, Alexander; Leo, Karl; Müller-Meskamp, Lars

    2015-02-14

    We present a novel top-electrode spray-coating process for the solution-based deposition of silver nanowires (AgNWs) onto vacuum-processed small molecule organic electronic solar cells. The process is compatible with organic light emitting diodes (OLEDs) and organic light emitting thin film transistors (OLETs) as well. By modifying commonly synthesized AgNWs with a perfluorinated methacrylate, we are able to disperse these wires in a highly fluorinated solvent. This solvent does not dissolve most organic materials, enabling a top spray-coating process for sensitive small molecule and polymer-based devices. The optimized preparation of the novel AgNW dispersion and spray-coating at only 30 °C leads to high performance electrodes directly after the deposition, exhibiting a sheet resistance of 10.0 Ω □(-1) at 87.4% transparency (80.0% with substrate). By spraying our novel AgNW dispersion in air onto the vacuum-processed organic p-i-n type solar cells, we obtain working solar cells with a power conversion efficiency (PCE) of 1.23%, compared to the air exposed reference devices employing thermally evaporated thin metal layers as the top-electrode.

  9. Investigation of Free-Standing Plasmonic Mesoporous Ag/CMK-8-Nafion Composite Membrane for the Removal of Organic Pollutants with 254-nm UV Irradiation

    Science.gov (United States)

    Tseng, Chuan Ming; Chen, Hsin Liang; Lai, Sz Nian; Chen, Ming Shiung; Peng, Chien Jung; Li, Chia Jui; Hung, Wei Hsuan

    2017-05-01

    "Carbon-based material" has demonstrated a great potential on water purification due to its strong physical adsorption to organic pollutants in the water. Three-dimensional cubic ordered mesoporous carbon (CMK-8), one of the well-known ordered mesoporous carbons, was prepared by using nanocasting method with mesoporous silica (KIT-6) as the template. In this study, CMK-8 blended with Nafion polymer to form a free-standing mesoporous CMK-8-Nafion composite membrane. The synthesis of high crystallinity CMK-8 was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). More than 80% methyl orange (MO) removal efficiency was observed under 254-nm UV irradiation after 120 min. Ninety-two percent recycling performance was remained after four recycling tests, which indicated a reliable servicing lifetime for the water purification. Furthermore, an additional layer of plasmonic silver nanoparticles (Ag NPs) was integrated into this CMK-8-Nafion membrane for higher pollutant removal efficiency, attributing from the generation of plasmon-resonance hot electrons from Ag NPs. A 4-in. CMK-8-Nafion composite membrane was also fabricated for the demonstration of potential large-scale utilization.

  10. Preparation and characterization of hybrid Nafion/silica and Nafion/silica/PTA membranes for redox flow batteries

    Energy Technology Data Exchange (ETDEWEB)

    Glibin, V.; Pupkevich, V.; Svirko, L.; Karamanev, D. [Western Ontario Univ., London, ON (Canada). Dept. of Biochemical and Chemical Engineering

    2008-07-01

    Redox flow batteries are both efficient and cost-effective. However, the long-term stability of most ion-exchange membranes is limited as a result of the high oxidation rates of ions with high redox potentials. A method of synthesizing multi-component Nafion-silica and Nafion-silica-PTA membranes was presented in this study, which also investigated the electrochemical and ion transport properties of the membranes. Membranes were cast from dimethylformamide (DMFA) solution. The iron ion diffusion kinetics of the Nafion-silica and Nafion-silica PTA membranes were studied by dialysis. Results of the investigation demonstrated that the introduction of silica and phosphotungstic acid (PTA) into the Nafion membrane composition resulted in a significant decrease of ion transfer through the membrane. The addition of PTA also increased membrane permeability to ferric ions. The low iron diffusion coefficient and high ionic conductivity of the Nafion-silica membrane makes it a promising material for use in redox flow batteries. 4 refs., 1 tab., 1 fig.

  11. Preparation and stability of silver/kerosene nanofluids.

    Science.gov (United States)

    Li, Dan; Fang, Wenjun

    2012-07-02

    A series of silver nanoparticles surface-coated with di-n-dodecyldithiophosphate, di-n-cetyldithiophosphate, or di-n-octadecyldithiophosphate have been prepared and have good dispersity in alkanes or kerosene. Stable silver nanofluids can be formed in alkanes or kerosene with the surface-coated silver nanoparticles. Thermal stability of the silver nanofluids has been measured at different temperatures. The effects of the silver nanoparticles on the thermal oxidation of kerosene have been investigated at different temperatures. The coatings can be released from the surface of the silver nanoparticles above 150°C, giving oxygen access to the silver core and inhibiting the kerosene oxidized by oxygen.

  12. Development of silver/titanium dioxide/chitosan adipate nanocomposite as an antibacterial coating for fruit storage

    Science.gov (United States)

    A novel nanocomposite of silver/titanium dioxide/chitosan adipate (Ag/TiO2/CS) was developed through photochemical reduction using a chitosan adipate template. Chitosan served as a reducing agent for the metal ions, and anchored metal ions by forming Ag–N coordination bonds and electrostatic attract...

  13. Synthesis of Silver-Doped Titanium TiO2 Powder-Coated Surfaces and Its Ability to Inactivate Pseudomonas aeruginosa and Bacillus subtilis

    Directory of Open Access Journals (Sweden)

    Saman Khan

    2013-01-01

    Full Text Available Hard, nonporous environmental surfaces in daily life are now receiving due recognition for their role in reducing the spread of several nosocomial infections. In this work, we established the photokilling effects of 1% silver-doped titanium dioxide TiO2. The nanoparticles synthesized by liquid impregnation method were characterized using X-ray diffraction (XRD, energy dispersive spectroscopy (EDS, and scanning electron microscopy (SEM. The Ag-TiO2 nanoparticle coatings that have been applied on glass and venetian blind surfaces were effective in generating a loss of viability of two bacteria (Pseudomonas aeruginosa and Bacillus subtilis after two hours of illumination under normal light in the visible spectrum. Such surfaces can be applicable to medical and other facilities where the potential for infection should be controlled.

  14. Double locked silver-coated silicon nanoparticle/graphene core/shell fiber for high-performance lithium-ion battery anodes

    Science.gov (United States)

    Gu, Minsu; Ko, Seunghee; Yoo, Seungmin; Lee, Eunhee; Min, Sa Hoon; Park, Soojin; Kim, Byeong-Su

    2015-12-01

    We present a fabrication of scalable coaxial core/shell silicon (Si)-graphene fiber prepared by dual-nozzle-induced wet-spinning assembly for high-performance Si anode. Over 50 wt% of Si nanoparticles mixed with graphene oxide suspension can be incorporated in the core with the outstanding dispersibility of unique silver-coated Si nanoparticles in aqueous media. The core fiber is further encapsulated by graphene shell which not only provides conducting pathways, but also alleviates severe volume expansion of Si core. This novel core/shell Si anode with double locked graphene architecture delivers more stable cycle performance and superior rate capability than anodes composed of simple mixture of Si-graphene composites.

  15. Separation of Silver Nanoparticles with Different Coatings by Capillary Electrophoresis Coupled to ICP-MS in Single Particle Mode.

    Science.gov (United States)

    Mozhayeva, Darya; Engelhard, Carsten

    2017-09-19

    The possibility of separating mixtures of Ag nanoparticles (NPs) with similar sizes but different surface coatings using capillary electrophoresis coupled to single particle inductively coupled mass-spectrometry (CE-SP-ICP-MS) was investigated. In two-component mixtures, it was possible to separate 40 nm sized polyvinylpirrolidone (PVP)- and citrate-coated NPs, 40 nm sized polyethylene glycol (PEG)- and citrate-coated NPs, and 60 nm sized PVP- and citrate-coated NPs. The separation of a more complex mixture containing NPs with the different coatings and sizes was successful, and each component, namely, 20, 40, and 60 nm sized citrate-coated and 40 and 60 nm sized PVP-coated NPs, could be distinguished. The theoretically expected migration order was confirmed by experimental results with selected Ag NPs. On the basis of the experimental observations, a separation mechanism that considers the effect of stable vs displaceable coatings during NP migration in CE is suggested. The ICP-MS was equipped with a prototype data acquisition system (μsDAQ) that provided 5 μs time resolution.

  16. Microbial biofilms on needleless connectors for central venous catheters: comparison of standard and silver-coated devices collected from patients in an acute care hospital.

    Science.gov (United States)

    Perez, Elizabeth; Williams, Margaret; Jacob, Jesse T; Reyes, Mary Dent; Chernetsky Tejedor, Sheri; Steinberg, James P; Rowe, Lori; Ganakammal, Satishkumar Ranganathan; Changayil, Shankar; Weil, M Ryan; Donlan, Rodney M

    2014-03-01

    Microorganisms may colonize needleless connectors (NCs) on intravascular catheters, forming biofilms and predisposing patients to catheter-associated infection (CAI). Standard and silver-coated NCs were collected from catheterized intensive care unit patients to characterize biofilm formation using culture-dependent and culture-independent methods and to investigate the associations between NC usage and biofilm characteristics. Viable microorganisms were detected by plate counts from 46% of standard NCs and 59% of silver-coated NCs (P=0.11). There were no significant associations (P>0.05, chi-square test) between catheter type, side of catheter placement, number of catheter lumens, site of catheter placement, or NC placement duration and positive NC findings. There was an association (P=0.04, chi-square test) between infusion type and positive findings for standard NCs. Viable microorganisms exhibiting intracellular esterase activity were detected on >90% of both NC types (P=0.751), suggesting that a large percentage of organisms were not culturable using the conditions provided in this study. Amplification of the 16S rRNA gene from selected NCs provided a substantially larger number of operational taxonomic units per NC than did plate counts (26 to 43 versus 1 to 4 operational taxonomic units/NC, respectively), suggesting that culture-dependent methods may substantially underestimate microbial diversity on NCs. NC bacterial communities were clustered by patient and venous access type and may reflect the composition of the patient's local microbiome but also may contain organisms from the health care environment. NCs provide a portal of entry for a wide diversity of opportunistic pathogens to colonize the catheter lumen, forming a biofilm and increasing the potential for CAI, highlighting the importance of catheter maintenance practices to reduce microbial contamination.

  17. Bovine Serum Albumin and Chitosan Coated Silver Nanoparticles and Its Antimicrobial Activity against Oral and Nonoral Bacteria

    Directory of Open Access Journals (Sweden)

    León Francisco Espinosa-Cristóbal

    2015-01-01

    Full Text Available Antimicrobial agents have been developed for drug-resistance infections, which have been rapidly increasing; however, the control of involved microorganisms is still a challenge. In this work, SNP with bovine serum albumin (BSA and chitosan (CS coatings were prepared with an aqueous reduction method, characterized using dispersion light scattering, transmission electron microscopy, and thermal analysis. Antibacterial activity was tested on seven oral and nonoral bacteria by microdilution test and scanning electron microscopy. Six different sizes and shapes of coated SNP were prepared and used. Characterization revealed narrow size and good distribution of particles, spherical and pseudospherical shapes, and the presence of coatings on the SNP surfaces. All samples showed antimicrobial activity, although smaller sizes and CS samples had the best inhibition effects. The highest microbial resistance was shown by Gram-positive bacteria. Although coated SNP action depends on particular bacterium, BSA and CS coated SNP could be used for drug-resistance infections.

  18. Silver coating effects on biofouling growth and morphology on heat transfer surfaces%换热表面镀银对微生物污垢的生长与形态的影响

    Institute of Scientific and Technical Information of China (English)

    杨倩鹏; 常思远; 史琳

    2013-01-01

    Silver ions provide bacteria sterilization effectively inhibit biofouling by bacteria.However,current research has mainly focused on the effects of silver ions in medical applications.For industrial applications like heat transfer surfaces,the effects of silver coatings on biofouling inhibition have rarely been reported.There are notable differences between silver ions in solution and silver coatings tihe the effectiveness dependent on the structure of the biofouling.There are also differences between planktonic bacteria in solution and in biofouling.This study focuses on the effects of silver on biofouling structures and growth rates to illustrate the mechanism and effectiveness of silver coatings.The results show the biofouling wet and dry weights both decreased more than 20% with a silver coating.The bottom biofouling layer became hollow and the bacteria cells in the biofouling within 100μm of the material surface showed decreased activity.%银离子溶液对悬浮细菌杀灭作用显著,对由细菌形成的微生物污垢也有明显抑制作用.当前,银离子溶液杀灭作用的研究主要集中在医学领域,对工业领域的换热器表面的镀银方式和微生物污垢形式涉及较少.镀银方式与银离子溶液作用机理有所差别,镀银方式与空间位置关系明显.微生物污垢形式,与菌液中悬浮细菌也有明显差异.该文从镀银对微生物污垢空间形态和重量曲线两方面出发,探讨了镀银抑垢的机理和效果.结果表明:镀银后污垢湿重量和干重量均下降20%以上.污垢底层空洞化,距离材料表面100 μm厚度以内污垢中的细胞活性下降.

  19. Tin Oxide-Silver Composite Nanomaterial Coating for UV Protection and Its Bactericidal Effect on Escherichia coli (E. coli

    Directory of Open Access Journals (Sweden)

    Gil Nonato C. Santos

    2014-05-01

    Full Text Available SnO2-Ag composite nanomaterials of mass ratio 1:4, 2:3, 3:2 and 4:1 were fabricated and tested for toxicity to E. coli using the pour-plate technique. The said nanomaterials were mixed with laminating fluid and then coated on glass slides. The intensity of UVA transmitted through the coated glass slides was measured. Results revealed that the 1:4 ratios of SnO2-Ag composite nanomaterials have the optimum toxicity to E. coli. Furthermore, the glass slides coated with SnO2 nanomaterial showed the lowest intensity of transmitted UVA.

  20. Release properties of titanium-based nano-silver coating%钛基表面纳米银复合涂层的缓释性能

    Institute of Scientific and Technical Information of China (English)

    鲜爱明; 张晓岗; 曹力; 王佳明; 彭理斌; 胡洋

    2014-01-01

    BACKGROUND:Surface modification of orthopedic implants can reduce or prevent bacterial adhersion. Bacteriostatic and bactericidal ingredients released from special coating of metal surfaces prevent orthopedic surgery infection. OBJECTIVE:To prepare hydroxyapatite/nano-silver composite coating on the surface of medical titanium based on different preparation parameters and to observe the release properties of silver ions on the composite material surface in the simulated body fluid. METHODS:Using pulse electrochemical methods, hydroxyapatite and nano-silver were deposited in the solution containing silver, calcium and phosphate ions. Scanning electron microscopy, X-ray diffraction and energy dispersive spectroscopy were used to characterize its morphology and composition. The composite titanium materials containing 0.5, 1 mmol/L silver were immersed in the simulated body fluid, and Ag+concentration was detected by atomic absorption spectrometry at the different time points. RESULTS AND CONCLUSION:Nanoparticles were uniformly distributed in the coating which was interwoven with the nano needle-like hydroxypatite and dot-like silver particles. After high temperature processing, the coating became denser, and hydroxypatite became more crystal and silver particles exhibited no agglomeration. In the simulated body fluid, Ag+release was maximal at 1-7 days and became stable at 7-30 days which maintained an effective antimicrobial concentration. The material containing 0.5 mmol/L Ag+showed a lower amount of Ag+released than cytotoxic concentration at 30 days, but the material containing 1 mmol/L Ag+could release the total of Ag+close to the critical value of celltoxicity at 30 days. Above al , the material containing 0.5 mmol/L Ag+is more secure in the clinical application.%背景:骨科植入材料表面改性可以减少或避免细菌黏附,利用金属表面的特殊涂层释放抑菌及杀菌成分可以预防骨科术后感染。目的:选择不同的制备

  1. Structure and Water Transport in Nafion Nanocomposite Membranes

    Science.gov (United States)

    Davis, Eric; Page, Kirt

    2014-03-01

    Perfluorinated ionomers, specifically Nafion, are the most widely used ion exchange membranes for vanadium redox flow battery applications, where an understanding of the relationship between membrane structure and transport of water/ions is critical to battery performance. In this study, the structure of Nafion/SiO2 nanocomposite membranes, synthesized using sol-gel chemistry, as well as cast directly from Nafion/SiO2 nanoparticle dispersions, was measured using both small-angle neutron scattering (SANS) and ultra-small-angle neutron scattering (USANS). Through contrast match studies of the SiO2 nanoparticles, direct information on the change in the structure of the Nafion membranes and the ion-transport channels within was obtained, where differences in membrane structure was observed between the solution-cast membranes and the membranes synthesized using sol-gel chemistry. Additionally, water sorption and diffusion in these Nafion/SiO2 nanocomposite membranes were measured using in situ time-resolved Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopy and dynamic vapor sorption (DVS).

  2. Krytox-Montmorillonite-Nafion registered nanocomposite membrane for effective methanol crossover reduction in DMFCs

    Energy Technology Data Exchange (ETDEWEB)

    Gosalawit, Rapee; Chirachanchai, Suwabun [The Petroleum and Petrochemical College, Chulalongkorn University, Chula Soi 12, Pathumwan, Bangkok (Thailand); Shishatskiy, Sergey; Nunes, Suzana P. [Institute of Polymer Research, GKSS Research Center Geesthacht GmbH, Max-Planck Street 1, 21502 Geesthacht (Germany)

    2007-12-15

    Nafion registered and Montmorillonite (MMT) functionalized with Krytox nanocomposite membrane (Krytox-MMT-Nafion registered) is proposed for DMFC applications. The nanocomposite is obtained with good compatibility between MMT and Nafion registered via the function of Nafion registered -like polymer chain namely Krytox 157 FSL. The MMT layers are exfoliated with Nafion registered polymer matrices and show homogeneity as confirmed by XRD and SEM. The AFM micrographs clarifies the successful MMT clay dispersion all over the nanocomposite membrane. The thermogravimetric analysis exhibits the improvement in water retention and thermal resistance as compared to Nafion registered membrane. The membranes perform for more than 50% reduction in the permeation of methanol in 10%(v/v) solution at either room temperature or as high as 60 C. The Arrhenius plot suggests the lower activation energy for proton migration in the Krytox-MMT-Nafion registered membranes than in the Nafion registered membrane under Grotthus mechanism. (author)

  3. Ultrafine Zinc and Nickel, Palladium, Silver Coated Zinc Particles Used for Reductive Dehalogenation of Chlorinated Ethylenes in Aqueous Solution

    OpenAIRE

    Li, Weifeng; Kenneth J. Klabunde

    1998-01-01

    Zero-valent zinc metal has been employed for the reductive dehalogenation of chlorinated ethylenes. In order to enhance this environmental remediation chemistry, ultrafine zinc particles and transition metal additives (coatings) have been employed. Indeed, activated zinc (cryozinc) significantly enhanced the reduction/dehalogenation process, especially in the presence of nickel and palladium coatings. These reagents were able to achieve rapid, deep reductive dehalogenation of trichloroethylen...

  4. A study aimed at characterizing the interfacial structure in a tin–silver solder on nickel-coated copper plate during aging

    Indian Academy of Sciences (India)

    D C Lin; R Kovacevic; T S Srivatsan; G X Wang

    2008-06-01

    This paper highlights the interfacial structure of tin-silver (Sn-3·5Ag) solder on nickel-coated copper pads during aging performance studies at a temperature of 150°C for up to 96 h. Experimental results revealed the as-solidified solder bump made from using the lead-free solder (Sn-3·5Ag) exhibited or showed a thin layer of the tin–nickel–copper intermetallic compound (IMC) at the solder/substrate interface. This includes a sub-layer having a planar structure immediately adjacent to the Ni-coating and a blocky structure on the inside of the solder. Aging performance studies revealed the thickness of both the IMC layer and the sub-layer, having a planar structure, to increase with an increase in aging time. The observed increase was essentially non-linear. Fine microscopic cracks were observed to occur at the interfaces of the planar sub-layer and the block sub-layer.

  5. A spray-coating process for highly conductive silver nanowire networks as the transparent top-electrode for small molecule organic photovoltaics

    Science.gov (United States)

    Selzer, Franz; Weiß, Nelli; Kneppe, David; Bormann, Ludwig; Sachse, Christoph; Gaponik, Nikolai; Eychmüller, Alexander; Leo, Karl; Müller-Meskamp, Lars

    2015-01-01

    We present a novel top-electrode spray-coating process for the solution-based deposition of silver nanowires (AgNWs) onto vacuum-processed small molecule organic electronic solar cells. The process is compatible with organic light emitting diodes (OLEDs) and organic light emitting thin film transistors (OLETs) as well. By modifying commonly synthesized AgNWs with a perfluorinated methacrylate, we are able to disperse these wires in a highly fluorinated solvent. This solvent does not dissolve most organic materials, enabling a top spray-coating process for sensitive small molecule and polymer-based devices. The optimized preparation of the novel AgNW dispersion and spray-coating at only 30 °C leads to high performance electrodes directly after the deposition, exhibiting a sheet resistance of 10.0 Ω □-1 at 87.4% transparency (80.0% with substrate). By spraying our novel AgNW dispersion in air onto the vacuum-processed organic p-i-n type solar cells, we obtain working solar cells with a power conversion efficiency (PCE) of 1.23%, compared to the air exposed reference devices employing thermally evaporated thin metal layers as the top-electrode.We present a novel top-electrode spray-coating process for the solution-based deposition of silver nanowires (AgNWs) onto vacuum-processed small molecule organic electronic solar cells. The process is compatible with organic light emitting diodes (OLEDs) and organic light emitting thin film transistors (OLETs) as well. By modifying commonly synthesized AgNWs with a perfluorinated methacrylate, we are able to disperse these wires in a highly fluorinated solvent. This solvent does not dissolve most organic materials, enabling a top spray-coating process for sensitive small molecule and polymer-based devices. The optimized preparation of the novel AgNW dispersion and spray-coating at only 30 °C leads to high performance electrodes directly after the deposition, exhibiting a sheet resistance of 10.0 Ω □-1 at 87

  6. Performance of Nafion® N115, Nafion® NR-212, and Nafion® NR-211 in a 1 kW Class All Vanadium Mixed Acid Redox Flow Battery

    Energy Technology Data Exchange (ETDEWEB)

    Reed, David M.; Thomsen, Edwin C.; Wang, Wei; Nie, Zimin; Li, Bin; Wei, Xiaoliang; Koeppel, Brian J.; Sprenkle, Vincent L.

    2015-07-01

    Three Nafion membranes of similar composition but different thicknesses were operated in a 3-cell 1kW class all vanadium mixed acid redox flow battery. The influence of current density on the charge/discharge characteristics, coulombic and energy efficiency, capacity fade, operating temperature and pressure drop in the flow circuit will be discussed and correlated to the Nafion membrane thickness. Material costs associated with the Nafion membranes, ease of handling the membranes, and performance impacts will also be discussed.

  7. Nafion/organically modified silicate hybrids membrane for vanadium redox flow battery

    Energy Technology Data Exchange (ETDEWEB)

    Teng, Xiangguo; Xi, Jingyu; Wu, Zenghua [Laboratory of Advanced Power Sources, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055 (China); Zhao, Yongtao; Qiu, Xinping [Laboratory of Advanced Power Sources, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055 (China); Key Laboratory of Organic Optoelectronics and Molecular, Tsinghua University, Beijing 100084 (China); Chen, Liquan [Laboratory of Advanced Power Sources, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055 (China); Laboratory for Solid State Ionics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China)

    2009-04-15

    In our previous work, Nafion/SiO{sub 2} hybrid membrane was prepared via in situ sol-gel method and used for the vanadium redox flow battery (VRB) system. The VRB with modified Nafion membrane has shown great advantages over that of the VRB with Nafion membrane. In this work, a novel Nafion/organically modified silicate (ORMOSIL) hybrids membrane was prepared via in situ sol-gel reactions for mixtures of tetraethoxysilane (TEOS) and diethoxydimethylsilane (DEDMS). The primary properties of Nafion/ORMOSIL hybrids membrane were measured and compared with Nafion and Nafion/SiO{sub 2} hybrid membrane. The permeability of vanadium ions through the Nafion/ORMOSIL hybrids membrane was measured using an UV-vis spectrophotometer. The results indicate that the hybrids membrane has a dramatic reduction in crossover of vanadium ions compared with Nafion membrane. Fourier transform infrared spectra (FT-IR) analysis of the hybrids membrane reveals that the ORMOSIL phase is well formed within hybrids membrane. Cell tests identify that the VRB with Nafion/ORMOSIL hybrids membrane presents a higher coulombic efficiency (CE) and energy efficiency (EE) compared with that of the VRB with Nafion and Nafion/SiO{sub 2} hybrid membrane. The highest EE of the VRB with Nafion/ORMOSIL hybrids membrane is 87.4% at 20 mA cm{sup -2}, while the EE of VRB with Nafion and the EE of VRB with Nafion/SiO{sub 2} hybrid membrane are only 73.8% and 79.9% at the same current density. The CE and EE of VRB with Nafion/ORMOSIL hybrids membrane is nearly no decay after cycling more than 100 times (60 mA cm{sup -2}), which proves the Nafion/ORMOSIL hybrids membrane possesses high chemical stability during long charge-discharge process under strong acid solutions. The self-discharge rate of the VRB with Nafion/ORMOSIL hybrids membrane is the slowest among the VRB with Nafion, Nafion/SiO{sub 2} and Nafion/ORMOSIL membrane, which further proves the excellent vanadium ions blocking characteristic of the prepared

  8. Chitosan-assisted buffer layer incorporated with hydroxypropyl methylcellulose-coated silver nanowires for paper-based sensors

    Science.gov (United States)

    Xu, Duohua; Qiu, Jingshen; Wang, Yucheng; Yan, Jiajun; Liu, Gui-Shi; Yang, Bo-Ru

    2017-06-01

    Fabricating flexible sensors on paper is intriguing. Here, we exploited chitosan as a buffer layer to facilitate the fabrication of silver nanowire (AgNW) networks and flexible devices on commercial paper. We found that the AgNW networks exhibited uniform distribution, smooth surface, and strong adhesion. The enhanced adhesion of AgNWs was attributed to the intermolecular hydrogen bonding between chitosan and hydroxypropyl methylcellulose (HPMC), which can be tailored by tuning the pH of the chitosan aqueous solution. This facile fabrication method utilizing biodegradable polymers and cost-effective AgNW ink holds great promise for portable, wearable, and disposable paper-based electronics.

  9. Study on the Technology of Micro Silver-coated Copper Powders in Conductive Ink%用于导电油墨的银包覆铜微粉工艺研究

    Institute of Scientific and Technical Information of China (English)

    李雅丽

    2012-01-01

    The micro size of copper powders were prepared by pre-reduction method using glucose in the ethyl-ene glycol system, and the micro silver type of copper-coated powders were directly made through substitution reaction method. By means of the laboratory experiment on the conductivity, the varieties of resistance value was discussed on the powders at different conditions. Therefore the optimum technology condition is confirmed to prepare the micro silver-coated copper powders.%在乙二醇体系中采用葡萄糖预还原法制备微米级铜粉,由直接置换法制备银包覆铜型微粉.通过导电性实验讨论不同条件下粉体的电阻值变化,确定了制备银包覆铜型微粉的最佳工艺条件.

  10. Inactivation of vegetative cells, but not spores, of Bacillus anthracis, B. cereus, and B. subtilis on stainless steel surfaces coated with an antimicrobial silver- and zinc-containing zeolite formulation.

    Science.gov (United States)

    Galeano, Belinda; Korff, Emily; Nicholson, Wayne L

    2003-07-01

    Stainless steel surfaces coated with paints containing a silver- and zinc-containing zeolite (AgION antimicrobial) were assayed in comparison to uncoated stainless steel for antimicrobial activity against vegetative cells and spores of three Bacillus species, namely, B. anthracis Sterne, B. cereus T, and B. subtilis 168. Under the test conditions (25 degrees C and 80% relative humidity), the zeolite coating produced approximately 3 log(10) inactivation of vegetative cells within a 5- to 24-h period, but viability of spores of the three species was not significantly affected.

  11. Nanostructured copper particles-incorporated Nafion-modified electrode for oxygen reduction

    Indian Academy of Sciences (India)

    T Selvaraju; R Ramaraj

    2005-10-01

    The electrocatalytic activity of nanostructured copper particles (represented as Cunano) incorporated Nafion (Nf) film-coated glassy carbon (GC) electrode (GC/Nf/Cunano) towards oxygen reduction was investigated in oxygenated 0.1 M phosphate buffer (pH 7.2). The electrodeposited Cunano in Nf film was characterized by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The electrocatalytic activity of Cunano at the modified electrode towards oxygen reduction was studied using cyclic voltammetry technique. The molecular oxygen reduction at the GC/Nf/Cunano-modified electrode started at a more positive potential than at a bare GC electrode. A possible reaction mechanism was proposed in which oxygen reduction may proceed through two-step two-electron processes at the GC/Nf/Cunano electrode. The GC/Nf/Cunano electrode shows higher stability for oxygen reduction in neutral solution and the electrode may find applications in fuel cells.

  12. Electrochemical and in situ spectroelectrochemical studies of gold nanoparticles immobilized Nafion matrix modified electrode

    Indian Academy of Sciences (India)

    T Selvaraju; S Sivagami; S Thangavel; R Ramaraj

    2008-06-01

    Electrochemical and in situ spectroelectrochemical behaviours of phenosafranine (PS+) were studied at the gold nanoparticles (AuNps) immobilized Nafion (Nf) film coated glassy carbon (GC) and indium tin oxide (ITO) electrodes. Cyclic voltammetric studies showed that the PS+ molecules strongly interact with the AuNps immobilized in the Nf matrix through the electrostatic interaction. The presence of AuNps in the Nf film improved the electrochemical characteristics of the incorporated dye molecules. The emission spectra of Nf–AuNps–PS+ films showed that the incorporated PS+ was quenched by AuNps and it could be explained based on the electronic interaction between the AuNps and PS+ molecules. The in situ spectroelectrochemical study showed an improved electrochemical characteristic of the incorporated PS+ molecules at the ITO/Nf–AuNps electrode when compared to the ITO/Nf electrode.

  13. 106 ASSESSMENT OF ANTI-BACTERIAL EFFECTS OF PEGYLATED SILVER-COATED CARBON NANOTUBES ON CAUSATIVE BACTERIA OF BOVINE INFERTILITY USING BIOLUMINESCENCE IMAGING SYSTEM.

    Science.gov (United States)

    Park, S; Chaudhari, A A; Pillai, S; Singh, S R; Willard, S T; Ryan, P L; Feugang, J M

    2016-01-01

    Pathogenic bacteria including Escherichia coli and Salmonella sp. are the major causative agents of endometritis and can cause infertility in livestock animals. Antibiotics are commonly used to terminate bacterial infections, but the development of bacterial antibiotic resistance is often encountered. Nanotechnology associated with silver nanoparticles has been highlighted as an alternative anti-bacterial agent, and pegylated silver-coated single-walled carbon nanotubes have high anti-bacterial effects and are non-toxic to human and murine cells in vitro. Here we verified whether a real-time bioluminescence monitoring system could be an alternative tool to assess anti-bacterial effects of nanotubes in a noninvasive approach. Escherichia coli and Salmonella sp. were transfected with plasmids containing constructs for luciferase enzyme (LuxCDABE) and substrate (luciferin) to create self-illuminating bioluminescent bacteria. Pathogens were grown in LB broth at 37°C, adjusted to 10(7) cfumL(-1), and placed in 96-well plates for treatments. Pegylated (pSWCNTs-Ag) and non-pegylated (SWCNTs-Ag) nanotubes were prepared and added to culture wells at various concentrations (31.25-125µgmL(-1)). The control group corresponded to bacteria without nanotubes (0µgmL(-1)). Anti-bacterial effects of nanotubes were determined every 10min until 1h, then every 30min up to 6h incubation through optical density (600nm) measurements and bioluminescence imaging (BLI) and quantification using an IVIS system. Optical density and BLI data were compared at each time-point using 2-way ANOVA, with PBioluminescence signals emitted by both bacteria stains appeared within 10min of incubation. Thereafter, control bacteria showed exponential growth that was detected as early as 25min post-incubation. Bioluminescence imaging revealed dose-dependent anti-bacterial activities of both pSWCNTs-Ag and SWCNTs-Ag on each E. coli and Salmonella sp. (P0.05); meanwhile, pSWCNTs-Ag nanotubes exhibited

  14. Zirconium oxide nanotube-Nafion composite as high performance membrane for all vanadium redox flow battery

    Science.gov (United States)

    Aziz, Md. Abdul; Shanmugam, Sangaraju

    2017-01-01

    A high-performance composite membrane for vanadium redox flow battery (VRB) consisting of ZrO2 nanotubes (ZrNT) and perfluorosulfonic acid (Nafion) was fabricated. The VRB operated with a composite (Nafion-ZrNT) membrane showed the improved ion-selectivity (ratio of proton conductivity to permeability), low self-discharge rate, high discharge capacity and high energy efficiency in comparison with a pristine commercial Nafion-117 membrane. The incorporation of zirconium oxide nanotubes in the Nafion matrix exhibits high proton conductivity (95.2 mS cm-1) and high oxidative stability (99.9%). The Nafion-ZrNT composite membrane exhibited low vanadium ion permeability (3.2 × 10-9 cm2 min-1) and superior ion selectivity (2.95 × 107 S min cm-3). The VRB constructed with a Nafion-ZrNT composite membrane has lower self-discharge rate maintaining an open-circuit voltage of 1.3 V for 330 h relative to a pristine Nafion membrane (29 h). The discharge capacity of Nafion-ZrNT membrane (987 mAh) was 3.5-times higher than Nafion-117 membrane (280 mAh) after 100 charge-discharge cycles. These superior properties resulted in higher coulombic and voltage efficiencies with Nafion-ZrNT membranes compared to VRB with Nafion-117 membrane at a 40 mA cm-2 current density.

  15. Nafion/Silicon Oxide Composite Membrane for High Temperature Proton Exchange Membrane Fuel Cell

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Nafion/Silicon oxide composite membranes were produced via in situ sol-gel reaction of tetraethylorthosilicate (TEOS) in Nafion membranes. The physicochemical properties of the membranes were studied by FT-IR, TG-DSC and tensile strength. The results show that the silicon oxide is compatible with the Nafion membrane and the thermo stability of Nafion/Silicon oxide composite membrane is higher than that of Nafion membrane. Furthermore, the tensile strength of Nafion/Silicon oxide composite membrane is similar to that of the Nafion membrane. The proton conductivity of Nafion/Silicon oxide composite membrane is higher than that of Nafion membrane. When the Nafion/Silicon oxide composite membrane was employed as an electrolyte in H2/O2 PEMFC, a higher current density value (1 000 mA/cm2 at 0.38 V) than that of the Nafion 1135 membrane (100 mA/cm2 at 0.04 V) was obtained at 110 ℃.

  16. About the Interactions Controlling Nafion's Viscoelastic Properties and Morphology

    NARCIS (Netherlands)

    Melchior, Jan-Patrick; Bräuniger, Thomas; Wohlfarth, Andreas; Portale, Giuseppe; Kreuer, Klaus-Dieter

    2015-01-01

    Interactions controlling the viscoelastic properties of Nafion are identified by investigating morphological changes induced through stretching at a wide range of controlled temperature and relative humidity. H-2-goniometer NMR exploiting the pseudonematic effect in D2O-containing membranes provides

  17. 纳米银羟基磷灰石涂层正畸陶瓷托槽的抗菌与力学性能%Antibacterial and mechanical properties of ceramic orthodontic brackets with nano silver hydroxyapatite coating

    Institute of Scientific and Technical Information of China (English)

    周冠军; 杨大鹏; 刘新芳; 胡博

    2015-01-01

    背景:临床口腔正畸过程中,陶瓷托槽存在抗菌性能和力学性能不足的情况,容易导致各种不良事件的出现,影响正畸效果。目的:观察纳米银羟基磷灰石涂层陶瓷托槽的抗菌与力学性能。方法:制备纳米银羟基磷灰石涂层陶瓷托槽,采用扫描电镜观察涂层表面,并进行涂层表面定量抗菌实验。将50颗离体人上颌前磨牙随机分为2组,实验组(n=25)粘接纳米银羟基磷灰石涂层陶瓷托槽,对照组(n=25)粘接普通陶瓷托槽,检测两组抗剪切强度。结果与结论:纳米银羟基磷灰石涂层整体结构有序,均匀致密,羟基磷灰石具有多孔状结构,孔径属于微纳米级别,其中均匀分布大量纳米银颗粒。定量抗菌实验显示,纳米银羟基磷灰石涂层陶瓷托槽对大肠杆菌、白色葡萄球菌有较强的抑制作用,抗菌率均在95%以上。实验组抗剪切强度低于对照组(P <0.05)。表明纳米银羟基磷灰石涂层陶瓷托槽具有良好的抗菌和力学性能,满足临床正畸过程中力学变化的需求。%BACKGROUND:In the clinical orthodontics, ceramic brackets have deficiencies in the aspects of antibacterial and mechanical properties, which easily lead to the emergence of a variety of adverse events and influence the orthodontic effect. OBJECTIVE:To observe the antibacterial and mechanical properties of nano silver hydroxyapatite coating ceramic brackets. METHODS:The nano silver hydroxyapatite coating ceramic brackets were prepared. Scanning electron microscopy was used to observe the coating surface. Coating antibacterial experiment was conducted. Totaly 50 in vitro human maxilary premolars were randomly divided into two groups (n=25 per group): experimental and control groups. Premolars in the experimental group were bonded to nano silver coating hydroxyapatite ceramic brackets, and premolars in the control group were bonded to ordinary ceramic brackets. The

  18. Impact of surface coating and environmental conditions on the fate and transport of silver nanoparticles in the aquatic environment.

    Science.gov (United States)

    Ellis, Laura-Jayne A; Valsami-Jones, Eugenia; Lead, Jamie R; Baalousha, Mohammed

    2016-10-15

    The role of surface coating (polyvinylpyrrolidone (PVP) and citrate) and water chemistry on the fate and behavior of AgNPs in aquatic microcosms is reported in this study. The migration and transformation of the AgNPs was examined in low (ultrapure water-UPW) and high ionic strength (moderately hard water - MHW) preparations, and in the presence of modeled natural organic matter (NOM) of Suwannee River Fulvic Acid (SRFA). The migration and fate of the AgNPs in the microcosms was validated using a sedimentation-diffusion model and the aggregation behavior was monitored by UV-visible spectrometry (UV-vis). Dissolved and particulate Ag concentrations (% Ag) were analyzed by ultrafiltration methods. Imaging of the AgNPs was captured using transmission electron microscopy (TEM). Results indicate that PVP-coated AgNPs (PVP-AgNPs) remained stable for 28days with similarly distributed concentrations of the PVP-AgNPs throughout the columns in each of the water conditions after approximately 96h (4days). The sedimentation-diffusion model confirmed PVP-AgNP stability in each condition, by showing diffusion dominated transport by using the original unaltered AgNP sizes to fit the parameters. In comparison, citrate AgNPs were largely unstable in the more complex water preparations (MHW). In MHW, aggregation dominated behavior followed by sedimentation/dissolution controlled transport was observed. The addition of SRFA to MHW resulted in small stabilizing effects, to the citrate coated AgNPs, producing smaller sized AgNPs (TEM) and mixed sedimentation and diffusion migration compared the studies absent of SRFA. The results suggest that surface coating and solution chemistry has a major impact on AgNP stability, furthermore the corresponding modeling will support the experimental understanding of the overall fate of AgNPs in the environment. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Conductive and corrosion behaviors of silver-doped carbon-coated stainless steel as PEMFC bipolar plates

    Institute of Scientific and Technical Information of China (English)

    Ming Liu; Hong-feng Xu; Jie Fu; Ying Tian

    2016-01-01

    Ni–Cr enrichment on stainless steel SS316L resulting from chemical activation enabled the deposition of carbon by spraying a stable suspension of carbon nanoparticles; trace Ag was depositedin situ to prepare a thin continuous Ag-doped carbon film on a porous carbon-coated SS316L substrate. The corrosion resistance of this film in 0.5 mol·L−1 H2SO4 solution containing 5 ppm F− at 80°C was inves-tigated using polarization tests. The results showed that the surface treatment of the SS316L strongly affected the adhesion of the carbon coating to the stainless steel. Compared to the bare SS316L, the Ag-doped carbon-coated SS316L bipolar plate was remarkably more stable in both the anode and cathode environments of proton exchange membrane fuel cell (PEMFC) and the interface contact resistance between the specimen and Toray 060 carbon paper was reduced from 333.0 mΩ·cm2 to 21.6 mΩ·cm2 at a compaction pressure of 1.2 MPa.

  20. Silver Doped TiO2 Nanostructure Composite Photocatalyst Film Synthesized by Sol-Gel Spin and Dip Coating Technique on Glass

    Directory of Open Access Journals (Sweden)

    Mojtaba Nasr-Esfahani

    2008-01-01

    Full Text Available New composite films (P25SGF-MC-Ag, MPC500SGF-MC-Ag, and ANPSGF-MC-Ag have been synthesized by a modified sol-gel method using different particle sizes of TiO2 powder and silver addition. Nanostructure TiO2/Ag composite thin films were prepared by a sol-gel spin and dip coating technique. while, by introducing methyl cellulose (MC porous, TiO2/Ag films were obtained after calcining at a temperature of 500°C. The as-prepared TiO2 and TiO2/Ag films were characterized by X-ray diffractometry, and scanning electron microscopy to reveal the structural and morphological differences. In addition, the photocatalytic properties of these films were investigated by degrading methyl orange (MO under UV irradiation. After 500°C calcination, the microstructure of MC-TiO2 film without Ag addition exhibited a microstructure, while significant sintering effect was noticed with Ag additions and the films exhibited a porous microstructure. Nanostructure anatase-phase TiO2 can be observed with respect to the sharpening of XRD diffraction peaks. The photodegradation of porous TiO2 deposited with 5×10−4 mol Ag exhibited the best photocatalytic efficiency, where 69% methyl orange can be decomposed after UV exposure for 1 hour.

  1. Preparation of silver nanowires coated with TiO2 using chemical binder and their applications as photoanodes in dye sensitized solar cell

    Science.gov (United States)

    Jang, Inseok; Kang, Taeho; Cho, Woohyung; Kang, Yong Soo; Oh, Seong-Geun; Im, Seung Soon

    2015-11-01

    In this study, the core-shell structured Ag@TiO2 wire was prepared for application to dye-sensitized solar cell (DSSC). The Ag nanowire, having an excellent electrical conductivity, was synthesized by using the facile microwave-assisted polyol reduction process. The diameter and length of Ag wires were 40-50 nm and 20-30 μm, respectively, and the face-centered cubic silver crystal structure was obtained. In the presence of 2-mercaptoethanol as a chemical binder, the entire surface of Ag wire was coated with the TiO2 shell, which has thickness of 20 nm, through solvothermal method. The crystalline structure of TiO2 shell was the anatase phase possessing an advantage to achieve the high efficiency in DSSC. The core-shell structured Ag@TiO2 wire exhibited the high thermal stability. The high conversion efficiency (5.56%) in fabricated device with Ag@TiO2 electrode, which is about 10% higher than reference cell, was achieved by enhancement of short-current density (Jsc) value. The core-shell structured Ag@TiO2 wire could effectively reduce the charge recombination through the contribution to electron shortcut for improvement in the electron transfer rate and lifetime.

  2. One-Step Synthesis of Silver Nanoparticles on Polydopamine-Coated Sericin/Polyvinyl Alcohol Composite Films for Potential Antimicrobial Applications

    Directory of Open Access Journals (Sweden)

    Rui Cai

    2017-04-01

    Full Text Available Silk sericin has great potential as a biomaterial for biomedical applications due to its good hydrophilicity, reactivity, and biodegradability. To develop multifunctional sericin materials for potential antibacterial application, a one-step synthesis method for preparing silver nanoparticles (AgNPs modified on polydopamine-coated sericin/polyvinyl alcohol (PVA composite films was developed. Polydopamine (PDA acted as both metal ion chelating and reducing agent to synthesize AgNPs in situ on the sericin/PVA composite film. Scanning electron microscopy and energy dispersive spectroscopy analysis revealed that polydopamine could effectively facilitate the high-density growth of AgNPs as a 3-D matrix. X-ray diffractometry studies suggested the synthesized AgNPs formed good face-centered cubic crystalline structures. Contact angle measurement and mechanical test indicated AgNPs modified PDA-sericin/PVA composite film had good hydrophilicity and mechanical property. The bacterial growth curve and inhibition zone assays showed the AgNPs modified PDA-sericin/PVA composite film had long-term antibacterial activities. This work develops a new method for the preparation of AgNPs modified PDA-sericin/PVA film with good hydrophilicity, mechanical performance and antibacterial activities for the potential antimicrobial application in biomedicine.

  3. One-Step Synthesis of Silver Nanoparticles on Polydopamine-Coated Sericin/Polyvinyl Alcohol Composite Films for Potential Antimicrobial Applications.

    Science.gov (United States)

    Cai, Rui; Tao, Gang; He, Huawei; Song, Kai; Zuo, Hua; Jiang, Wenchao; Wang, Yejing

    2017-04-30

    Silk sericin has great potential as a biomaterial for biomedical applications due to its good hydrophilicity, reactivity, and biodegradability. To develop multifunctional sericin materials for potential antibacterial application, a one-step synthesis method for preparing silver nanoparticles (AgNPs) modified on polydopamine-coated sericin/polyvinyl alcohol (PVA) composite films was developed. Polydopamine (PDA) acted as both metal ion chelating and reducing agent to synthesize AgNPs in situ on the sericin/PVA composite film. Scanning electron microscopy and energy dispersive spectroscopy analysis revealed that polydopamine could effectively facilitate the high-density growth of AgNPs as a 3-D matrix. X-ray diffractometry studies suggested the synthesized AgNPs formed good face-centered cubic crystalline structures. Contact angle measurement and mechanical test indicated AgNPs modified PDA-sericin/PVA composite film had good hydrophilicity and mechanical property. The bacterial growth curve and inhibition zone assays showed the AgNPs modified PDA-sericin/PVA composite film had long-term antibacterial activities. This work develops a new method for the preparation of AgNPs modified PDA-sericin/PVA film with good hydrophilicity, mechanical performance and antibacterial activities for the potential antimicrobial application in biomedicine.

  4. 代银镀层技术研究进展%Advances in Research on Plating Technology of Substitute for Silver Coating

    Institute of Scientific and Technical Information of China (English)

    王崇蕊; 郝建军; 董春艳; 刘新院

    2011-01-01

    Several plating methods of substitute for Silver coating such as tin electroplating with sulfate electrolyte, Sn-Ce and acid bright Sn-Ce-Bi alloy electroplating were described. Ni-P/Ni-B double-layer electroless plating, and tin electroless plating followed by Sn-Ce-Sb electroplating method were also introduced. The characteristics of these plating methods were briefly summarized, and the developing trends of these methods were put forward.%介绍了几种替代银镀层的镀覆方法,其中有硫酸盐电解液镀锡、电镀锡-铈合金、酸性光亮镀锡-铈-铋合金等.化学镀Ni-P/Ni-B双层合金镀层,电镀和化学镀相结合的方法有化学镀锡和电镀锡-铈-锑合金.并归纳了各种代银镀层方法的特点,指出了代银镀层技术的发展趋势.

  5. A study of the effects of citrate-coated silver nanoparticles on RAW 264.7 cells using a toolbox of cytotoxic endpoints

    Science.gov (United States)

    Bastos, V.; Duarte, I. F.; Santos, C.; Oliveira, H.

    2017-05-01

    Citrate-coated silver nanoparticles (citrate-AgNPs) are among the most commonly used nanomaterials, widely present in industrial and biomedical products. In this study, the cytotoxicity of 30-nm citrate-AgNPs on the macrophage cell line RAW 264.7 was evaluated, using a battery of cytotoxicity endpoints (viability, oxidative stress, and cytostaticity/clastogenicity), at 24 and 48 h of exposure. Citrate-AgNPs decreased cell proliferation and viability only at 75 μg/mL, suggesting a low sensitivity of RAW cells to lower doses of these AgNPs. After 24 h of exposure, ROS content decreased in cells exposed to 60 μg/mL AgNPs (IC20 value), corroborating the high tolerance of these cells to citrate-AgNPs. However, these cells suffered an impairment of the cell cycle, shown by an increase at the sub-G1 phase. This increase of the sub-G1 population was correlated with an increase of DNA fragmentation, suggesting an increase of apoptosis. Thus, our data are important to understand the effects of low concentrations (IC20) of citrate-AgNPs on in vitro vital macrophage functions.

  6. Silver Sulfadiazine

    Science.gov (United States)

    Silver sulfadiazine, a sulfa drug, is used to prevent and treat infections of second- and third-degree ... Silver sulfadiazine comes in a cream. Silver sulfadiazine usually is applied once or twice a day. Follow ...

  7. Preparation, proton conductivity and mechanical properties of Nafion 117-zirconium phosphate sulphophenylphosphonate composite membranes

    Energy Technology Data Exchange (ETDEWEB)

    Capitani, D. [Istituto di Metodologie Chimiche, CNR, Monterotondo Scalo (Italy); Donnadio, A.; Frittella, V.; Pica, M.; Sganappa, M. [CEMIN - Dipartimento di Chimica, Perugia (Italy); Casciola, M.

    2009-08-15

    Nafion-zirconium phosphate (ZrP) composite membranes, containing 20 to 40 wt.-% ZrP were treated with aqueous solutions of meta-sulphophenylphosphonic acid (H{sub 2}SPP) in order to functionalise the filler particles with strongly acidic sulphonic groups. The functionalised samples (Nafion/ZrSPP) were characterised by {sup 31}P MAS NMR, water uptake determinations, stress-strain mechanical tests and conductivity measurements. The Nafion/ZrSPP membranes are more hydrophilic than Nafion 117 and stiffer than the parent Nafion/ZrP membranes: at room temperature, the elastic modulus of the membranes with 20 and 40 wt.-% ZrP increases from 191 and 329 N mm{sup -2} to 342 and 470 N mm{sup -2}, respectively, after functionalisation. At 100 C and in the RH range of 30-90% the conductivity of the Nafion/ZrSPP membranes decreases with the increase in the filler loading, being however always higher than that of the parent Nafion/ZrP membranes and nearly coincident with that of Nafion 117. Conductivity measurements as a function of temperature in the range of 80-150 C showed that, at 90% RH, the conductivity of the Nafion/ZrSPP membranes is stable up to 140 C thus indicating a better dimensional stability of the composite membrane in comparison with neat Nafion 117. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  8. Green engineering of biomolecule-coated metallic silver nanoparticles and their potential cytotoxic activity against cancer cell lines

    Science.gov (United States)

    Prasannaraj, Govindaraj; Venkatachalam, Perumal

    2017-06-01

    This report describes the synthesis of metallic silver nanoparticles (AgNPs) using extracts of four medicinal plants (Aegle marmelos (A. marmelos), Alstonia scholaris (A. scholaris), Andrographis paniculata (A. paniculata) and Centella asiatica (C. asiatica)). The bio-conjugates were characterized by UV-visible spectroscopy, scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), Fourier transform infrared spectrometry (FTIR), x-ray diffraction (XRD) and zeta potential. This analysis confirmed that UV-Vis spectral peaks at 375 nm, 380 nm, 420 nm and 380 nm are corresponding to A. marmelos, A. scholaris, A. paniculata and C. asiatica mediated AgNPs, respectively. SEM images revealed that all the obtained four AgNPs are predominantly spherical, fibres and rectangle in shape with an average size of 36-97 nm. SEM-EDS and XRD analysis confirmed the presence of elemental AgNPs in crystalline form for all the four nanoparticle samples. The phytochemicals of various medicinal plant extracts with different functional groups were responsible for reduction of Ag+ to AgNPs, which act as capping and stabilizing agent. Among four types of AgNPs tested for anticancer activity, the Ap mediated AgNPs had shown enhanced activity against HepG2 cells (27.01 µg ml-1) and PC3 cells (32.15 µg ml-1).

  9. Long-lasting in vivo and in vitro antibacterial ability of nanostructured titania coating incorporated with silver nanoparticles.

    Science.gov (United States)

    Cheng, Hao; Li, Yong; Huo, Kaifu; Gao, Biao; Xiong, Wei

    2014-10-01

    Although titanium (Ti) implants are widely used clinically, implant-associated bacterial infection is still one of the most serious complications in orthopedic surgery. Long-term antibacterial properties and the ability to inhibit biofilm formation are highly desirable to prevent implant associated infection. In this study, a controllable amount of silver (Ag) nanoparticles was incorporated into titanium oxide; or titanium, nanotubes (TiO₂ -NTs). The reliable release and long-term antibacterial function of Ag, in vivo and in vitro, and influence normal bone-implant integration from the Ag released from Ag-incorporated NTs in vivo have been studied to make them useable in clinical practice. In the current study, TiO₂ -NTs loaded with Ag (NT-Ag) exhibited strong antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA, ATCC43300) in vitro for 30 days, and the ability to penetrate the protein layer well. In addition, X-ray examination and 2-[(18)F]-fiuoro-2-deoxy-D-glucose positron emission tomography indicates that NT-Ag show extremely long antibacterial activity in vivo in a rat model. Furthermore, histomorphometric analysis demonstrated that satisfactory bio-integration can be expected. Our results indicate that NT-Ag has both simultaneous antimicrobial and excellent bio-integration properties, make it a promising therapeutic material for orthopedic application.

  10. Hierarchical Nafion enhanced carbon aerogels for sensing applications

    Science.gov (United States)

    Weng, Bo; Ding, Ailing; Liu, Yuqing; Diao, Jianglin; Razal, Joselito; Lau, King Tong; Shepherd, Roderick; Li, Changming; Chen, Jun

    2016-02-01

    This work describes the fabrication of hierarchical 3D Nafion enhanced carbon aerogels (NECAGs) for sensing applications via a fast freeze drying method. Graphene oxide, multiwalled carbon nanotubes and Nafion were mixed and extruded into liquid nitrogen followed by the removal of ice crystals by freeze drying. The addition of Nafion enhanced the mechanical strength of NECAGs and effective control of the cellular morphology and pore size was achieved. The resultant NECAGs demonstrated high strength, low density, and high specific surface area and can achieve a modulus of 20 kPa, an electrical conductivity of 140 S m-1, and a specific capacity of 136.8 F g-1 after reduction. Therefore, NECAG monoliths performed well as a gas sensor and as a biosensor with high sensitivity and selectivity. The remarkable sensitivity of 8.52 × 103 μA mM-1 cm-2 was obtained in dopamine (DA) detection, which is two orders of magnitude better than the literature reported values using graphene aerogel electrodes made from a porous Ni template. These outstanding properties make the NECAG a promising electrode candidate for a wide range of applications. Further in-depth investigations are being undertaken to probe the structure-property relationship of NECAG monoliths prepared under various conditions.This work describes the fabrication of hierarchical 3D Nafion enhanced carbon aerogels (NECAGs) for sensing applications via a fast freeze drying method. Graphene oxide, multiwalled carbon nanotubes and Nafion were mixed and extruded into liquid nitrogen followed by the removal of ice crystals by freeze drying. The addition of Nafion enhanced the mechanical strength of NECAGs and effective control of the cellular morphology and pore size was achieved. The resultant NECAGs demonstrated high strength, low density, and high specific surface area and can achieve a modulus of 20 kPa, an electrical conductivity of 140 S m-1, and a specific capacity of 136.8 F g-1 after reduction. Therefore, NECAG

  11. A Plasmonic Coupling Substrate Based on Sandwich Structure of Ultrathin Silica-Coated Silver Nanocubes and Flower-Like Alumina-Coated Etched Aluminum for Sensitive Detection of Biomarkers in Urine.

    Science.gov (United States)

    Nguyen, Minh-Kha; Su, Wei-Nien; Hwang, Bing-Joe

    2017-05-01

    Interactions between substrate and plasmonic nanostructures can give rise to unique optical properties and influence performance in plasmonic biosensing applications. In this study, a substrate with low refractive index and roughness based on flower-like alumina-coated etched aluminum foil (f-Al2 O3 /e-Al) has been fabricated. Silver@silica (Ag@SiO2 ) nanocubes (NCs) assemble in an edge-edge configuration when deposited on this substrate. The rough surface texture of f-Al2 O3 /e-Al provides a pathway for coupling of incident light to surface plasmons. The Ag@SiO2 /f-Al2 O3 /e-Al substrate exhibits a coupling efficiency of laser light sources into surface plasmon hotspots for both surface-enhanced Raman scattering (SERS) and metal-enhanced photoluminescence (MEPL). Moreover, the shelf life of this substrate is significantly improved due to a reduction in oxygen diffusion rate mediated by the ultrathin silica spacer and the flower-like Al2 O3 dielectric layer. Creatinine and flavin adenine dinucleotide are biomolecules present in human blood and urine. With advanced label-free SERS and MEPL techniques, it is possible to detect these biomarkers in urine, allowing cheap, noninvasive, yet sensitive analysis. The approach explored in this work can be developed into a powerful encoding tool for high-throughput bioanalysis. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Experimental and theoretical studies on localized surface plasmon resonance based fiber optic sensor using graphene oxide coated silver nanoparticles

    Science.gov (United States)

    Nayak, Jeeban Kumar; Parhi, Purnendu; Jha, Rajan

    2016-07-01

    An optical fiber based refractive index sensor using graphene oxide (GO) encapsulated silver nanoparticles (AgNPs) is reported. The AgNPs are encapsulated with a very thin layer of GO as it controls the inter-particle distance thereby preventing aggregation. The encapsulation also enhances the colloidal stability and prevents the oxidation of the AgNPs by separating them from direct contact with the aqueous medium. High-resolution transmission electron microscopy results support the formation of 1 nm thick GO around AgNPs of an average size of 35 nm. A Raman spectrometer and a UV-VIS spectrometer have been used to characterize and study the synthesized nanoparticles along with GO. Further, Raman spectra support a 64.72% increase in D-peak intensity and a 52.91% increase in G-peak intensity of the GO-encapsulated AgNPs (GOE-AgNPs) with respect to GO. Further, the GOE-AgNPs are immobilized on the core of functionalized plastic-cladded silica fiber. FESEM confirms the immobilization of the GOE-AgNPs on the fiber core. We observed that the peak absorbance changes by 87.55% with a 0.05 change in the refractive index. The sensitivity of the proposed fiber sensor is found to be 0.9406 ΔA/RIU along with a resolution of 12.8  ×  {{10}-4} RIU. MATLAB is used to calculate the absorbance of the AgNPs by considering the bound and free electron contribution along with the size-dependent dispersion of the nanoparticles. We found that the simulation results are in good agreement with the experimental results.

  13. Interaction between Nafion ionomer and noble metal catalyst for PEMFCs

    DEFF Research Database (Denmark)

    Andersen, Shuang Ma

    The implement of polymer impregnation in electrode structure (catalyst layer) decreasing the noble metal catalyst loading by a factor of ten , , is one of the essential mile stones in the evolution of Proton Exchange Membrane Fuel Cells’ development among the application of catalyst support...... and electrode deposition etc. In fuel cell reactions, both electrons and protons are involved. Impregnation of Nafion ionomer in catalyst layer effectively increases the proton-electron contact, enlarge the reaction zone, extend the reaction from the surface to the entire electrode. Therefore, the entire...... catalyst layer conducts both electrons and protons so that catalyst utilization in the layer is improved dramatically. The catalyst layer will in turn generate and sustain a higher current density. One of the generally adapted methods to impregnate Nafion into the catalyst layer is to mix the catalysts...

  14. Property modification of Nafion via polymer blending with ethylene vinyl alcohol "polyimide" (Conference Presentation)

    Science.gov (United States)

    Hwang, Taeseon; Nam, Jungsoo; Shen, Qi; Trabia, Sarah; Suhr, Jonghwan; Lee, Dong-Chan; Kim, Kwang Jin

    2016-04-01

    The blended ion exchange membrane between Nafion and ethylene vinyl alcohol (EVOH) was used for fabrication of the ionic polymer-metal composite (IPMC) to redeem inherent drawbacks of Nafion such as high cost or environment-unfriendliness. EVOH solution was blended in Nafion solution by a volume ratio of 15 and 30 % membranes were prepared through solution casting method. The prepared blended Nafion membranes can be fabricated IPMCs with deposition of platinum electrode onto its surface without crack or delamination. The surface resistance of all prepared IPMCs is measured through 2 point probe. This study investigated the chemical structure and thermal properties of prepared membranes. Moreover, we characterized the cross-section morphology and studied the electromechanical performances (displacement and blocking force) of prepared IPMC actuators. The IPMC actuators with proposed blended Nafion membranes were demonstrated comparable electromechanical performance by significantly reducing the content of Nafion.

  15. Visualization of ion transport in Nafion using electrochemical strain microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Suran; No, Kwangsoo; Hong, Seungbum

    2015-12-24

    The electromechanical response of a Nafion membrane immersed in water was probed using electrochemical strain microscopy (ESM) to redistribute protons and measure the resulting local strain that is caused by the movement of protons. We also measured the relaxation of protons from the surface resulting from proton diffusion. Using this technique, we can visualize and analyze the local strain change resulting from the redistribution and relaxation of hydrated protons.

  16. ZnO-MWCNTs/Nafion inorganic-organic composite film:Preparation and application in bioelectrochemistry of hemoglobin

    Institute of Scientific and Technical Information of China (English)

    Wei Ma; Wei Song; Dan Bi Tian

    2009-01-01

    Multi-walled carbon nanombes (MWCNTs) were coated with ZnO by a hydrothermal method. The resulting nanocomposites were mixed with the Nation solution to form a composite matrix for the fabrication of hemoglobin (Hb) biosensor. To prevent the leak of Hb molecules of the biosensor, silica sol-gel film was coated on the surface of the Hb/ZnO-MWCNTs/Nafion electrode. The silica sol-gel/Hb/ZnO-MWCNTs/Nation film exhibited a pair of well-defined, quasi-reversible redox peaks. This biosensor showed excellent electrocatalytic activity to H2O2. The sensitivity and apparent Michaelis-Menten constant of this Hb biosensor to H2O2 were 1.31 A/(M cm2) and 82.8 umol/L, respectively, which indicated that Hb had high affinity to H2O2.

  17. Performance of Nafion® N115, Nafion® NR-212, and Nafion® NR-211 in a 1 kW class all vanadium mixed acid redox flow battery

    Science.gov (United States)

    Reed, David; Thomsen, Edwin; Wang, Wei; Nie, Zimin; Li, Bin; Wei, Xiaoliang; Koeppel, Brian; Sprenkle, Vincent

    2015-07-01

    Three Nafion® membranes of similar composition but different thicknesses were operated in a 3-cell 1 kW class all vanadium mixed acid redox flow battery. The influence of current density on the charge/discharge characteristics, coulombic and energy efficiency, capacity fade, operating temperature and pressure drop in the flow circuit will be discussed and correlated to the Nafion® membrane thickness. Material costs associated with the Nafion® membranes, ease of handling the membranes, and performance impacts will also be discussed.

  18. Multiple splice variants within the bovine silver homologue (SILV gene affecting coat color in cattle indicate a function additional to fibril formation in melanophores

    Directory of Open Access Journals (Sweden)

    Weikard Rosemarie

    2007-09-01

    Full Text Available Abstract Background The silver homologue(SILV gene plays a major role in melanosome development. SILV is a target for studies concerning melanoma diagnostics and therapy in humans as well as on skin and coat color pigmentation in many species ranging from zebra fish to mammals. However, the precise functional cellular mechanisms, in which SILV is involved, are still not completely understood. While there are many studies addressing SILV function upon a eumelaneic pigment background, there is a substantial lack of information regarding the further relevance of SILV, e.g. for phaeomelanosome development. Results In contrast to previous results in other species reporting SILV expression exclusively in pigmented tissues, our experiments provide evidence that the bovine SILV gene is expressed in a variety of tissues independent of pigmentation. Our data show that the bovine SILV gene generates an unexpectedly large number of different transcripts occurring in skin as well as in non-pigmented tissues, e.g. liver or mammary gland. The alternative splice sites are generated by internal splicing and primarily remove complete exons. Alternative splicing predominantly affects the repeat domain of the protein, which has a functional key role in fibril formation during eumelanosome development. Conclusion The expression of the bovine SILV gene independent of pigmentation suggests SILV functions exceeding melanosome development in cattle. This hypothesis is further supported by transcript variants lacking functional key elements of the SILV protein relevant for eumelanosome development. Thus, the bovine SILV gene can serve as a model for the investigation of the putative additional functions of SILV. Furthermore, the splice variants of the bovine SILV gene represent a comprehensive natural model to refine the knowledge about functional domains in the SILV protein. Our study exemplifies that the extent of alternative splicing is presumably much higher than

  19. The platinum microelectrode/Nafion interface - An electrochemical impedance spectroscopic analysis of oxygen reduction kinetics and Nafion characteristics

    Science.gov (United States)

    Parthasarathy, Arvind; Dave, Bhasker; Srinivasan, Supramaniam; Appleby, John A.; Martin, Charles R.

    1992-01-01

    The objectives of this study were to use electrochemical impedance spectroscopy (EIS) to study the oxygen-reduction reaction under lower humidification conditions than previously studied. The EIS technique permits the discrimination of electrode kinetics of oxygen reduction, mass transport of O2 in the membrane, and the electrical characteristics of the membrane. Electrode-kinetic parameters for the oxygen-reduction reaction, corrosion current densities for Pt, and double-layer capacitances were calculated. The production of water due to electrochemical reduction of oxygen greatly influenced the EIS response and the electrode kinetics at the Pt/Nafion interface. From the finite-length Warburg behavior, a measure of the diffusion coefficient of oxygen in Nafion and diffusion-layer thickness was obtained. An analysis of the EIS data in the high-frequency domain yielded membrane and interfacial characteristics such as ionic conductivity of the membrane, membrane grain-boundary capacitance and resistance, and uncompensated resistance.

  20. A new high-performance ionic polymer-metal composite based on Nafion/polyimide blends

    Science.gov (United States)

    Nam, Jungsoo; Hwang, Taeseon; Kim, Kwang Jin; Lee, Dong-Chan

    2017-03-01

    For the first time, we report ion-exchange membranes based on Nafion and polyimide (PI, Kapton) blends to fabricate ionic polymer-metal composites (IPMCs). Polyamic acid [PAA, poly(pyromellitic dianhydride-co-4,4‧-oxydianiline), as a precursor of PI] solution was blended with Nafion solution using physical blending method to provide PAA-Nafion blend membrane. This work demonstrates that, by simple physical blending method, the thermal and mechanical properties of Nafion can be improved while maintaining the excellent actuating performance. After thermal imidization, PAA converted into PI, resulting in PI-Nafion blend membrane. Optimum conditions to cast PAA-Nafion blends and thermal imidization have been established, and blend membranes with PI wt% of 6, 12, 18, and 30 were prepared. Fourier transform infrared spectroscopy confirmed the incorporation of PI in the Nafion matrix. Thermal decomposition unique to the PI became more noticeable as the content of PI increased, which was measured by thermogravimetric analysis. Dynamic mechanical analysis showed that the storage modulus (E‧) increased as a function of PI content while loss modulus (E″) exhibited only a minor change, which resulted in the decrease in the damping properties (tan δ). The blend membranes were fabricated into IPMCs by deposition of platinum electrode onto the membrane surface through electroless plating process. Among tested, NPI-18 IPMC actuator, which has 18 wt% of PI in Nafion, showed comparable electromechanical performance to the commercially available Nafion 117 IPMC actuator.

  1. Nafion/PTFE composite membranes for direct methanol fuel cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Hsiu-Li; Yu, T. Leon; Chen, Li-Chung [Department of Chemical Engineering and Materials Science, Yuan Ze University, Nei-Li, Taoyuan 32026 (Taiwan); Huang, Li-Ning; Shen, Kun-Sheng; Jung, Guo-Bin [Fuel Cell Center, Yuan Ze University, Nei-Li, Taoyuan 32026 (Taiwan)

    2005-10-04

    Using dynamic light scattering and scanning electron microscope (SEM), it is shown that a high-carbon-number alcohol/water, i.e., 2-propanol/water, mixed solvent is more effective than low-carbon-number alcohol/water, i.e., ethanol/water and methanol/water, mixed solvents in dispersing Nafion molecules. Thus, it is a better solvent for the preparation of Nafion/PTFE (poly(tetrafluoroethylene)) composite membranes. The performance of direct methanol fuel cells (DMFCs) with a Nafion/PTFE composite membrane, which was prepared in-house, a commercial Nafion-117 membrane, or a commercial Nafion-112 membrane were investigated by feeding various concentrations, i.e., 2-5M, of methanol to the anode. The Nafion/PTFE composite membrane gave a better DMFC performance than that obtained with Nafion-117 or Nafion-112 membranes. Using a DMFC model and varying the methanol concentration at the anode, cell voltage data were analyzed with respect to methanol concentration and cell current. The results indicate that inserting porous PTFE into Nafion polymer causes a reduction not only in methanol diffusion cross-over but also in the electro-osmosis of methanol cross-over in the membrane. (author)

  2. Anhydrous proton conducting membranes for PEM fuel cells based on Nafion/Azole composites

    Energy Technology Data Exchange (ETDEWEB)

    Sen, Unal; Ata, Ali [Gebze Institute of Technology, Materials Science and Engineering, Gebze, Kocaeli (Turkey); Uenueguer Celik, Sevim; Bozkurt, Ayhan [Department of Chemistry, Fatih University, 34500, Buyukcekmece, Istanbul (Turkey)

    2008-06-15

    Proton conducting membranes are the most crucial part of energy generating electrochemical systems such as polymer electrolyte membrane fuel cells (PEMFCs). In this work, Nafion based proton conducting anhydrous composite membranes were prepared via two different approaches. In the first, commercial Nafion115 and Nafion112 were swelled in the concentrated solution of azoles such as 1H-1,2,4-triazole (Tri), 3-amino-1,2,4-triazole (ATri) and 5-aminotetrazole (ATet) as heterocyclic protogenic solvents. In the second, the proton conducting films were cast from the Nafion/Azole solutions. The partial protonation of azoles in the anhydrous membranes were studied by Fourier transform infrared (FT-IR) spectroscopy. Thermal properties were investigated via thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). TGA results showed that Nafion/ATri and Nafion/ATet electrolytes are thermally stable at least up to 200 C. Methanol permeability measurements showed that the composite membranes have lower methanol permeability compared to Nafion112. Nafion115/ATri system has better conductivity at 180 C, exceeding 10{sup -3} S/cm compared to other Nafion/heterocycle systems under anhydrous conditions. (author)

  3. The measurement of silver diffusivity in zirconium carbide to study the release behavior of 110mAg in the ZrC TRISO-coated nuclear fuel particle

    Science.gov (United States)

    Yang, Young-Ki; Allen, Todd R.

    2016-03-01

    The tri-structural isotropic (TRISO) coated particle fuel has been developed and used for high temperature gas-cooled reactors (HTGRs). It provides a unique robustness of the first barrier for the fission products. The TRISO fuel particle has typically consisted of a UO2 or UCO kernel, surrounded by successive layers of porous carbon, dense inner pyrocarbon, silicon carbide, and dense outer pyrocarbon. During operation, however, the SiC layer has been known to release radioactive silver 110mAg which makes maintenance more difficult and thus costly. Zirconium carbide has been considered as a promising alternative to the SiC fission product barrier. ZrC exhibits high temperature stability and possibly possesses superior Pd resistance, while the retention properties especially for silver have not been adequately studied. To help elucidate the diffusive behavior of silver in the ZrC coating of the TRISO-coated particle, a new diffusion experimental technique, called the encapsulating source method, has been developed by constructing a constant source diffusion couple between ZrC and Ag gas originated from Zr-Ag solid solution. Scanning electron microscopy (SEM), wavelength-dispersive X-ray spectroscopy (WDS), electron backscatter diffraction (EBSD) and optical methods were used to analyze the diffusion couple annealed at 1500 °C. The resultant diffusion coefficient of Ag in single-crystalline ZrC0.84 at 1500 °C was experimentally determined to be about 2.8 (±1.2) × 10-17 m2/s.

  4. Technologies and Performances of Silver-coated Copper Powder Prepared by Displacement Reaction%置换还原法制备银包铜粉工艺及性能研究

    Institute of Scientific and Technical Information of China (English)

    宋曰海; 马丽杰

    2013-01-01

    Silver-coated copper powder was prepared by displacement reaction using EDTA as the complexing agent.The effects of the concentration of reducing agent,dispersant as well as the complexing agent on the performances of silver-coated copper powder were investigated.The results showed that the powder prepared by displacement reaction using EDTA as the complexing agent was in dense and uniform state.When the concentration of complexing agent and reducing agent was all 0.12 mol/L and the ultrasonic dispersion was conducted,the prepared silver-coated copper powder possessed optimal conductivity with dense structure,silvery white color,high clad ratio and best antioxidation.%采用EDTA为络合剂,利用置换还原法制备银包铜粉.研究了还原剂的浓度,分散剂以及络合剂的浓度对银包铜粉性能的影响.实验结果表明,采用EDTA为络合剂,所得粉末表层结构致密,包覆均匀.当c(EDTA)为0.12 mol/L,c(葡萄糖)为0.12 mol/L,同时采用超声波分散,所得银包铜粉导电性最好,镀银层致密,粉末为银白色,包覆率高,抗氧化性最佳.

  5. The measurement of silver diffusivity in zirconium carbide to study the release behavior of {sup 110m}Ag in the ZrC TRISO-coated nuclear fuel particle

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Young-Ki, E-mail: deltag@naver.com; Allen, Todd R., E-mail: allen@engr.wisc.edu

    2016-03-15

    The tri-structural isotropic (TRISO) coated particle fuel has been developed and used for high temperature gas-cooled reactors (HTGRs). It provides a unique robustness of the first barrier for the fission products. The TRISO fuel particle has typically consisted of a UO{sub 2} or UCO kernel, surrounded by successive layers of porous carbon, dense inner pyrocarbon, silicon carbide, and dense outer pyrocarbon. During operation, however, the SiC layer has been known to release radioactive silver {sup 110m}Ag which makes maintenance more difficult and thus costly. Zirconium carbide has been considered as a promising alternative to the SiC fission product barrier. ZrC exhibits high temperature stability and possibly possesses superior Pd resistance, while the retention properties especially for silver have not been adequately studied. To help elucidate the diffusive behavior of silver in the ZrC coating of the TRISO-coated particle, a new diffusion experimental technique, called the encapsulating source method, has been developed by constructing a constant source diffusion couple between ZrC and Ag gas originated from Zr–Ag solid solution. Scanning electron microscopy (SEM), wavelength-dispersive X-ray spectroscopy (WDS), electron backscatter diffraction (EBSD) and optical methods were used to analyze the diffusion couple annealed at 1500 °C. The resultant diffusion coefficient of Ag in single-crystalline ZrC{sub 0.84} at 1500 °C was experimentally determined to be about 2.8 (±1.2) × 10{sup −17} m{sup 2}/s. - Highlights: • Developed new diffusion experimental method in lieu of problematic existing method. • Measured concentration profiles of Ag in ZrC after diffusion annealing. • Firstly determined diffusion coefficient of Ag in ZrC at 1500 °C.

  6. 载银纳米氧化钛涂层抗菌性能的初步研究%Primary study on the antibacterial property of silver-loaded nano-titania coatings

    Institute of Scientific and Technical Information of China (English)

    冯宇; 曹聪; 李宝娥; 刘宣勇; 董宇启

    2008-01-01

    Objective To study the preparation and characteristics of silver-loaded nano-titania coating so as to develop a bioactive implant material with antibacterial property.Methods Plasma sprayed nano-titania coatings were immersed in 1%,5%,and 9% AgNO3 solution to load silver.The loaded silver and its distribution were evaluated by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS).After optimizing the preparation process,the release rate of silver from the nano-titania coating was measured in deionized water,its corresponding in vitro cytotoxicity and antibacterial activity were also examined.Results The loaded silver was in proper quantity and distributed evenly on the nano-titania coatings after immersion in 5% AgNO3.A burst release of the silver could be detected.The quick release of silver from the titania coatings sustained about 12 days in deionized water,which had no obvious influence on the surface morphology of titania coatings.The loaded silver did not inhibit the osteoblast proliferation (P = 0.1 ) and alkaline phosphatase expression (P = 0.06 ),however,it effectively inhibited the survival and growth of Staphylococcus aureus for 12 days:the zone of inhibition reached 3.81±0.8 mm with a bacteria killing rate of 100%.Conclusions It is economical and effective to prepare the silver-loaded nano-titania coatings by 5% AgNO3 solution.The loaded silver has good antibacterial function,and shows no obvious effect on the physical and biological properties of nano-titania coatings.%目的 探讨载银纳米氧化钛生物陶瓷涂层的制备和表征,以期获得具抗菌作用的植入物涂层材料.方法 将等离子体喷涂纳米氧化钛涂层浸入1%、5%、9%的硝酸银溶液中载银,通过背散射电镜和能谱仪考察各自载银量和银分布,选择合适的载银工艺.对以该工艺制备的载银涂层进行银离子缓释、成骨细胞毒性和体外抗菌性能试验.结果 5%硝酸银溶液使得涂层载银量适

  7. Characterization of Nafion ionomer and its change due to X radiation; Caracterizacao do ionomero Nafion e sua modificacao por irradiacao de raios X

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, Selma Helena de

    1996-07-01

    In this study, first the characterization of Nafion-117 membranes in the acid form (Nafion-H) and in the salt forms (Na{sup +}, K{sup +}, Rb{sup +} and Cs{sup +}) was performed. In another step, the X-ray effects on membranes (Nafion-H and Nafion-Na) were investigated. The samples were irradiated with X-ray, at 160 kGy/h, with 80-1280 kGy dosages. The characterization of samples (irradiated and unirradiated samples) was performed by X-ray diffractometry, vibrational spectroscopy (photoacoustic in infrared region and Raman scattering), electronic absorption spectroscopy (UV/Vis), electronic paramagnetic resonance spectroscopy (EPR) and thermal analysis (TG and DCS). The studies showed that the membranes submitted to high temperature or to hydration structural changes, as evidence by IR and UV/Vis spectra and DSC curves. This behavior can be assigned to the reorganization of the clusters, resulting in redistribution of the ions and reorientation of the polymers. UV/Vis spectra and DSC curves indicates that the conformational changes induced by temperature and hydration effect continue to occur slowly in the membrane due to relaxation of the polymer. TG analysis indicated that the thermal decomposition mechanism by Nafion-H is different from the mechanism by Nafion-Na. Nafion-H membranes degraded in at least three stages, while Nafion-Na membranes, which showed higher thermal stability than Nafion-H, degraded in only one stage. For irradiation dose higher than 320 kGy, the samples became brittle, which enhanced with increasing doses. This behavior indicates that the predominant effect was the chain scission. The results obtained by different technique showed that the main effects of X-rays on Nafion membranes are the following: decrease in the mechanical properties, peroxy radical production, formation of unsaturated species (C=C and C=O), scissions in the C-O and C-S bonds and SO{sub 2} production. The Nafion-Na membrane showed higher thermal stability and higher

  8. Amino-silica modified Nafion membrane for vanadium redox flow battery

    Science.gov (United States)

    Lin, Chien-Hong; Yang, Ming-Chien; Wei, Hwa-Jou

    2015-05-01

    A hybrid membrane of Nafion/amino-silica (amino-SiO2) for vanadium redox flow battery (VRB) systems is prepared via the sol-gel method to improve the selectivity of the Nafion membrane, to reduce the crossover of vanadium ions, and to decrease water transfer across the membranes. The sulfonated pores of the pristine Nafion membrane are filled with amino-SiO2 nanoparticles localized by electrostatic interaction. The permeability of vanadium ions through the Nafion/amino-SiO2 hybrid membrane is determined by electrometric titration. The results indicate the crossover of vanadium ions through the hybrid membrane is 26.8% of the pristine Nafion membrane. The presence of amino-SiO2 in the hybrid membrane is verified by X-ray photoelectron spectroscopy (XPS). Nafion/amino-SiO2 hybrid membrane exhibits through plane conductivity about the same as the pristine Nafion membrane. The ion exchange capacity (IEC) of the hybrid membrane is 9.4% higher than that of the pristine Nafion membrane. In addition, Nafion/amino-SiO2 hybrid membrane exhibits a higher coulombic efficiency (CE), voltage efficiency (VE), and energy efficiency (EE) over a range of current densities from 20 to 80 mA cm-2. The performance of VRB with Nafion/amino-SiO2 hybrid membrane varies little around a charge-discharge current density of 80 mA cm-2 for 150 cycles. Thus, the Nafion/amino-SiO2 hybrid membrane can suppress the vanadium ions crossover in VRB.

  9. Carbon nanotubes-Nafion composites as Pt-Ru catalyst support for methanol electro-oxidation in acid media

    Institute of Scientific and Technical Information of China (English)

    Shengzhou Chen; Fei Ye; Weiming Lin

    2009-01-01

    Carbon nanotubes-Nafion (CNTs-Nafion) composites were prepared by impregnated CNTs with Nafion in ethanol solution and characterized by FT-IR. Pt-Ru catalysts supported on CNTs-Nafion composites were synthesized by microwave-assisted polyol process. The physical and electrochemical properties of the catalysts were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), CO stripping voltammetry, cyclic voltammetry (CV) and chronoamperometry (CA). The results showed that the Nafion incorporation in CNTs-Nafion composites did not significantly alter the oxygen-containing groups on the CNTs surface. The Pt-Ru catalyst supported on CNTs-Nafion composites with 2 wt% Nafion showed good dispersion and the best CO oxidation and methanol electro-oxidation activities.

  10. 镀银铜粉电磁屏蔽水性涂料的制备及性能研究%Preparation of Silver Plated Copper Electromagnetic Shielding Waterborne Coatings and Its Property

    Institute of Scientific and Technical Information of China (English)

    李桃安; 毛倩瑾; 郑付营; 崔素萍; 兰明章; 王子明; 王亚丽

    2011-01-01

    Electromagnetic shielding waterborne coatings was developed, with acrylic emulsion and silver plated copper powder as main raw material, wetting agent, dispersing agent, defoamer, leveling agent and water as additives. The process of coating preparation is as following: first, wetting agent, dispersing agent, first part of defoamer and silver plated copper were mixed, then emulsion was added and stired for some time, lastly leveling agent and the rest of defoamer were put into to obtain electromagnetic shielding coatings. The effects of the content of silver plated copper powder, water, and different emulsion on the conductivity and electromagnetic shielding property were discussed by conductive mechanism,electromagnetic shielding theory and the microcosmic structure of coatings. The shielding efficiency of the electromagnetic shielding waterborne coatings is 55-65 dB at range of frequency 100 kHz—1.5 GHz.%以丙烯酸类乳液和片状镀银铜粉为主要原料,添加润湿剂、分散剂、消泡剂、流平剂和水,制备得到电磁屏蔽水性涂料.涂料的制备工艺为:先将润湿剂、分散剂、部分消泡剂和镀银铜粉进行搅拌混合,再加入乳液搅拌均匀,最后加入流平剂和余下消泡剂制得屏蔽涂料.讨论了镀银铜粉含量、乳液种类及用水量对涂层导电性和电磁屏蔽性能的影响,并从导电机理、电磁屏蔽原理和涂层微观结构方面进行了分析.所制备的涂料在100kHz-1.5 GHz的频率范围内,其屏蔽效能达到55-65dB.

  11. Electrostatic self-assembly Pd particles on NafionTM membrane surface to reduce methanol crossover

    Institute of Scientific and Technical Information of China (English)

    TANG Haolin; PAN Mu; MU Shichun; YUAN Runzhang

    2005-01-01

    @@ NafionTM perfluorosulfonate proton exchange membranes (PEM) have been widely used as solid electrolytes in direct methanol fuel cell (DMFC) because it possesses relatively good mechanical strength and chemical stability. Due to its structure of side chains fixed at CF backbones, phase separation occurs between hydrophilic regions and hydrophobic ones in hydrated NafionTM membrane[1].

  12. Sulfonated graphene oxide/nafion composite membrane for vanadium redox flow battery.

    Science.gov (United States)

    Kim, Byung Guk; Han, Tae Hee; Cho, Chang Gi

    2014-12-01

    Nafion is the most frequently used as the membrane material due to its good proton conductivity, and excellent chemical and mechanical stabilities. But it is known to have poor barrier property due to its well-developed water channels. In order to overcome this drawback, graphene oxide (GO) derivatives were introduced for Nafion composite membranes. Sulfonated graphene oxide (sGO) was prepared from GO. Both sGO and GO were treated each with phenyl isocyanate and transformed into corresponding isGO and iGO in order to promote miscibility with Nafion. Then composite membranes were obtained, and the adaptability as a membrane for vanadium redox flow battery (VRFB) was investigated in terms of proton conductivity and vanadium permeability. Compared to a pristine Nafion, proton conductivities of both isGO/Nafion and iGO/Nafion membranes showed less temperature sensitivity. Both membranes also showed quite lower vanadium permeability at room temperature. Selectivity of the membrane was the highest for isGO/Nafion and the lowest for the pristine Nafion.

  13. Electrodeposition of Platinum and Ruthenium Nanoparticles in Multiwalled Carbon Nanotube-Nafion Nanocomposite for Methanol Electrooxidation

    Directory of Open Access Journals (Sweden)

    Yu-Huei Hong

    2009-01-01

    Full Text Available PtRu nanoparticles with a diameter of 10–15 nm were electrodeposited within multiwalled carbon nanotube-Nafion (MWCNT-Nafion nanocomposite. The formation of PtRu nanoparticles in MWCNT-Nafion nanocomposite was characterized by scanning electron microscopy, transmission electron microscopy, and energy dispersive X-ray spectroscopy. The electrocatalytic activity towards the methanol electrooxidation at PtRu-MWCNT-Nafion and Pt-MWCNT-Nafion nanocomposite-modified glassy carbon electrodes was investigated by cyclic voltammetry. The results indicated that the PtRu-MWCNT-Nafion nanocomposite was electrocatalytically more active than Pt-MWCNT-Nafion nanocomposite. The effect of atomic ratio of Pt : Ru on the electrocatalytic ability towards the methanol electrooxidation was investigated in order to achieve a high catalyst use. The PtRu bimetallic catalyst with 1 : 1 atomic ratio showed better electrocatalytic activity towards the methanol electrooxidation. The stability for the methanol electrooxidation at PtRu-MWCNT-Nafion nanocomposite modified was also investigated.

  14. Preparation of L-Butyl Lactate via Transesterification by Using Nafion-H Catalyst

    Institute of Scientific and Technical Information of China (English)

    Wei LI; Guo Rong ZHENG; Ping LU

    2005-01-01

    Optically pure L-butyl lactate was synthesized by normal transesterification using nafion-H catalyst in moderate yield. Various reaction conditions were investigated, including the reaction temperature, reaction time, ratio of the starting material and amount of the nafion catalyst.

  15. Nafion/SiO2 Nanocomposites: High Potential Catalysts for Alkylation of Benzene with Linear C9-C13 Alkenes

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    High surface area Nafion/SiO2 nanocomposites with nano-sized Nafion resin particles entrapped and dispersed within the highly porous silica matrix exhibited significantly enhanced activity, high selectivity and long-term stability for the alkylation of benzene with linear C9-C13 alkenes owing to the increased accessibility of Nafion resin-based acid sites to reactants.

  16. Gravimetric and volumetric determination of the purity of electrolytically refined silver and the produced silver nitrate

    Directory of Open Access Journals (Sweden)

    Ačanski Marijana M.

    2007-01-01

    Full Text Available Silver is, along with gold and the platinum-group metals, one of the so called precious metals. Because of its comparative scarcity, brilliant white color, malleability and resistance to atmospheric oxidation, silver has been used in the manufacture of coins and jewelry for a long time. Silver has the highest known electrical and thermal conductivity of all metals and is used in fabricating printed electrical circuits, and also as a coating for electronic conductors. It is also alloyed with other elements such as nickel or palladium for use in electrical contacts. The most useful silver salt is silver nitrate, a caustic chemical reagent, significant as an antiseptic and as a reagent in analytical chemistry. Pure silver nitrate is an intermediate in the industrial preparation of other silver salts, including the colloidal silver compounds used in medicine and the silver halides incorporated into photographic emulsions. Silver halides become increasingly insoluble in the series: AgCl, AgBr, AgI. All silver salts are sensitive to light and are used in photographic coatings on film and paper. The ZORKA-PHARMA company (Sabac, Serbia specializes in the production of pharmaceutical remedies and lab chemicals. One of its products is chemical silver nitrate (argentum-nitricum (l. Silver nitrate is generally produced by dissolving pure electrolytically refined silver in hot 48% nitric acid. Since the purity of silver nitrate, produced in 2002, was not in compliance with the p.a. level of purity, there was doubt that the electrolytically refined silver was pure. The aim of this research was the gravimetric and volumetric determination of the purity of electrolytically refined silver and silver nitrate, produced industrially and in a laboratory. The purity determination was carried out gravimetrically, by the sedimentation of silver(I ions in the form of insoluble silver salts: AgCl, AgBr and Agi, and volumetrically, according to Mohr and Volhardt. The

  17. Application of silver - coated antimicrobial dressings in pressure ulcer with infection%银离子抗菌敷料在感染性压疮护理中的应用

    Institute of Scientific and Technical Information of China (English)

    徐云侠

    2011-01-01

    Objective To assess the antibacterial activity of silver - coated antimicrobial dressings in pressure ulcer with infection. Methods 42 patients with infected pressure ulcers were divided into two groups:the experimental group and the control group. The experi mental group, 22 patients with 26 pressure ulcers, was treated with silver- coated antimicrobial dressings, while the control group, 20 pa tients with 23 pressure ulcers, received a treatment with traditional care. Dressings'effectiveness , days of treatment, frequencies of change dressings and the cost of the treatment were evaluated and compared between two groups. Results Compared with the control group, the in fections of all pressure ulcers were under control and there were significant differences in the days to healing and in the number of dressings changes in the experimental group, whereas there was no significant increase in the cost per ulcer of dressings between the two groups. Con clusion The nursing procedure of silver - coated antimicrobial dressings is convenient and the silver dressings is demonstrated beneficial in healing ulcer infection.%目的 探讨银离子抗菌敷料在感染性压疮护理中的应用效果.方法 42例感染性压疮患者分为试验组和对照组,其中试验组22例,感染性压疮共26处;对照组20例,感染性压疮共23处;试验组采用银离子抗菌敷料治疗护理,而对照组采用传统的纱布敷料护理,比较两组患者伤口感染控制前的治疗时间、换药次数以及换药费用等情况.结果 与对照组比较,银离子抗菌敷料对感染的控制率达100%,并能够明显缩短压疮感染控制时间,减少换药次数,而且两组敷料费用差异无统计学意义.结论 银离子抗菌敷料护理操作方便,对感染性压疮具有很好的治疗效果.

  18. Thermal Stability of Temperable Mono-silver Coated Low-E Glass%可钢化单银low-E镀膜玻璃的耐热性能

    Institute of Scientific and Technical Information of China (English)

    王永斌; 孙震; 余刚; 杨幼然; 郭明; 汪洪

    2012-01-01

    低辐射(Low-E)镀膜玻璃膜层的热稳定性对可钢化产品质量影响很大,在Low-E镀膜玻璃的钢化工艺中,由于加热温度过高或加热时间过长,可能会造成一些缺陷,如弯曲,波形,脱膜,色差,麻点等。本文用马弗炉对相同膜系的可钢化单银low-E玻璃进行了不同加热温度、不同保温时间下的耐热实验;通过观察外观变化,测试颜色变化、色差,及其方块电阻、E值、透过率、雾度等随温度和保温时间的变化关系,研究了相同膜系结构的可钢低辐射镀膜玻璃的耐热性能;为产品膜系结构设计,质量风险评估提供参考。%Thermal stability of low-E glass has a great effect on the quality of tempered products.Owning to high temperature or long heating time,defects in low-E glass such as bending,wave-forming,stripping,color differences and pitting may be caused by tempering.Thermal experiments on temperable mono-silver coated low-E glasses were performed under different temperatures and heating times by using a muffle furnace.Variations of appearance,color,color differences,sheet resistance,E value,transmittance and haze with the heating temperature and heating time were observed and tested in order to reveal their relationship.Thermal stability of temperable low-E glass was studied which can offer references for film design and quality risk assessment.

  19. Nanocharacterization and nanofabrication of a Nafion thin film in liquids by atomic force microscopy.

    Science.gov (United States)

    Umemura, Kazuo; Wang, Tong; Hara, Masahiko; Kuroda, Reiko; Uchida, On; Nagai, Masayuki

    2006-03-28

    We demonstrated the nanocharacterization and nanofabrication of a Nafion thin film using atomic force microscopy (AFM). AFM images showed that the Nafion molecules form nanoclusters in water, in 5% methanol, and in acetic acid. Young's modulus E of a Nafion film was estimated by sequential force curve measurements in water and in 5% methanol on one sample surface. Ewater/E5% methanol was 1.75 +/- 0.40, so the film was much softer in 5% methanol than in water. Even when solvent was replaced from 5% methanol to water, Young's modulus was not recovered soon. We showed the first example of the mechanical properties of a Nafion film on the nanoscale. Furthermore, we succeeded in fabricating 3D nanostructures on a Nafion surface by AFM nanolithography in liquids. Our results showed the new potential of the AFM nanolithography of a polymer film by softening the molecules in liquids.

  20. Progress in Fabrication of Gold and Silver Nanoparticles Coated Core-shell Microspheres%金、银纳米粒子包覆核壳结构微球的制备与研究进展

    Institute of Scientific and Technical Information of China (English)

    王晨; 古宏晨

    2011-01-01

    金、银纳米粒子包覆的核-壳结构微球在众多领域具有许多潜在的应用功能,也是近几年来的一个研究热点。本文分析和讨论了金、银纳米粒子包覆的核-壳结构微球的制备方法,包括静电自组装法、原位还原法、晶种生长法、化学镀法、超声法、一步合成法等;简述了金、银纳米粒子包覆的核壳结构微球的优异性能及其应用,并对其发展前景进行了展望。%Gold and silver nanoparticles coated core-shell microspheres have drew much attention in many areas due to their diverse potential applications.In this paper,several fabrication strategies are analyzed and discussed,including the electrostatic self-assembly,in-situ reduction,seeding,electroless plating,ultrasonic method,and one-pot synthesis method.The outstanding properties and applications of gold and silver nanoparticles coated core-shell microspheres are briefly summarized and their prospect is also addressed.

  1. Spray deposition of Nafion membranes: Electrode-supported fuel cells

    Science.gov (United States)

    Bayer, Thomas; Pham, Hung Cuong; Sasaki, Kazunari; Lyth, Stephen Matthew

    2016-09-01

    Fuel cells are a key technology for the successful transition towards a hydrogen society. In order to accelerate fuel cell commercialization, improvements in performance are required. Generally, polymer electrolyte membrane fuel cells (PEFCs) are membrane-supported; the electrocatalyst layer is sprayed onto both sides of the membrane, and sandwiched between carbon-based gas diffusion layers (GDLs). In this work we redesign the membrane electrode assembly (MEA) and fabricate an electrode-supported PEFC. First the electrocatalyst layer is sprayed onto the GDL, and then Nafion dispersion is sprayed over the top of this to form a thin membrane. This method has the advantage of simplifying the fabrication process, allowing the fabrication of extremely thin electrolyte layers (down to ∼10 μm in this case), and reducing the amount of ionomer required in the cell. Electrode-supported PEFCs operate at significantly increased power density compared to conventional membrane-supported PEFCs, with a maximum of 581 mW/cm2 at 80 °C (atmospheric pressure, air at the cathode). Impedance spectroscopy confirmed that the origin of the improved performance was an 80% reduction in the membrane resistance due the thinner Nafion layer. This novel fabrication method is a step towards cheaper, thinner, fully printable PEFCs with high power density and efficiency.

  2. Low-temperature synthesis of nano-TiO{sub 2} anatase on nafion membrane for using on DMFC

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen Manh Tuan; Nguyen Hoang Tuyen [Ho Chi Minh City Institute of Physics, Vietnam Academy of Science and Technology (VAST), 01 Mac Dinh Chi Street, 1 District, Ho Chi Minh City (Viet Nam); Ngo Thanh Nha [Can Tho University, Can Tho (Viet Nam)], E-mail: manhtuan2k@yahoo.com

    2009-09-01

    Low-temperature synthesis of 60-70 deg. C of anatase nanocrystalline titanium dioxide TiO{sub 2} using sol-gel technique on Nafion membrane is investigated and characterized. Titan tetraisopropoxide (TTIP) is used as precursor and ethanol as the solvent. The best precursor to solvent weight ratio has been used for the synthesis of nano-TiO{sub 2} particles. The X-ray diffractograms and TEM images show the formation of anatase structure of nanocrystalline TiO{sub 2} at low temperatures as shown with average particle size below 12 nm. The films deposited by spin coating technique using these nanoparticles show the crystalline and porous nature of the films. The nano-TiO{sub 2} film as shown can be used to reduce the cross-over permeation of methanol through the PEM and increase electric power of the DMFC.

  3. Impedance Spectroscopic Investigation of Proton Conductivity in Nafion Using Transient Electrochemical Atomic Force Microscopy (AFM

    Directory of Open Access Journals (Sweden)

    Emil Roduner

    2012-06-01

    Full Text Available Spatially resolved impedance spectroscopy of a Nafion polyelectrolyte membrane is performed employing a conductive and Pt-coated tip of an atomic force microscope as a point-like contact and electrode. The experiment is conducted by perturbing the system by a rectangular voltage step and measuring the incurred current, followed by Fourier transformation and plotting the impedance against the frequency in a conventional Bode diagram. To test the potential and limitations of this novel method, we present a feasibility study using an identical hydrogen atmosphere at a well-defined relative humidity on both sides of the membrane. It is demonstrated that good quality impedance spectra are obtained in a frequency range of 0.2–1,000 Hz. The extracted polarization curves exhibit a maximum current which cannot be explained by typical diffusion effects. Simulation based on equivalent circuits requires a Nernst element for restricted diffusion in the membrane which suggests that this effect is based on the potential dependence of the electrolyte resistance in the high overpotential region.

  4. Impedance Spectroscopic Investigation of Proton Conductivity in Nafion Using Transient Electrochemical Atomic Force Microscopy (AFM)

    Science.gov (United States)

    Hink, Steffen; Wagner, Norbert; Bessler, Wolfgang G.; Roduner, Emil

    2012-01-01

    Spatially resolved impedance spectroscopy of a Nafion polyelectrolyte membrane is performed employing a conductive and Pt-coated tip of an atomic force microscope as a point-like contact and electrode. The experiment is conducted by perturbing the system by a rectangular voltage step and measuring the incurred current, followed by Fourier transformation and plotting the impedance against the frequency in a conventional Bode diagram. To test the potential and limitations of this novel method, we present a feasibility study using an identical hydrogen atmosphere at a well-defined relative humidity on both sides of the membrane. It is demonstrated that good quality impedance spectra are obtained in a frequency range of 0.2–1000 Hz. The extracted polarization curves exhibit a maximum current which cannot be explained by typical diffusion effects. Simulation based on equivalent circuits requires a Nernst element for restricted diffusion in the membrane which suggests that this effect is based on the potential dependence of the electrolyte resistance in the high overpotential region. PMID:24958175

  5. Effect of Nafion ionometer content on proton conductivity in the catalyst layer of proton exchange fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Ozalevlia, Cihan Cemil; Jian Xie; Xu, Fan [METU MS Mechanical Engineering (United States)], email: cihan.ozalevli@metu.edu.tr, email: jianxie@iupui.edu, email: fanxu@iupui.edu

    2011-07-01

    In the energy conversion sector, proton exchange fuel cells (PEFC's) are among the most promising technologies for the future. The Nafion ionometer is the most important part of the membrane electrode assembly (MEA) which is the core technology of the system. The Nafion ionometer is both a proton conductor and a binder for the catalyst layer in the technology. The aim of this study is to assess the effect of the Nafion content in the cathode catalyst layer on the proton conductivity of the MEA. Two MEAs with different Nafion content were prepared following the LANL process and the proton conductivity of the catalyst layer was measured. Results showed a much higher performance of the 28wt. % Nafion MEA than the 10wt. %. This study demonstrated that when the Nafion ionometer content decreases, the performance of the fuel cell decreases; further investigations should be undertaken with Nafion ionometer amounts of 15wt. % to 20wt. %.

  6. Incorporation of Hyperbranched Supramolecules into Nafion Ionic Domains via Impregnation and In-Situ Photopolymerization

    Directory of Open Access Journals (Sweden)

    Hiruto Kudo

    2011-11-01

    Full Text Available Nafion membranes were impregnated with photocurable supramolecules, viz., hyperbranched polyester having pendant functional carboxylic acid groups (HBPEAc-COOH by swelling in methanol and subsequently photocured in-situ after drying. Structure-property relationships of the HBPEAc-COOH impregnated Nafion membranes were analyzed on the basis of Fourier transform infrared (FTIR spectroscopy, solid-state nuclear magnetic resonance (SSNMR and dynamic mechanical analysis (DMA. FTIR and SSNMR investigations revealed that about 7 wt % of HBPEAc-COOH was actually incorporated into the ionic domains of Nafion. The FTIR study suggests possible complexation via inter-species hydrogen bonding between the carboxylic groups of HBPEAc-COOH and the sulfonate groups of Nafion. The α-relaxation peak corresponding to the glass transition temperature of the ionic domains of the neat Nafion-acid form was found to increase from ~100 to ~130 °C upon impregnation with enhanced modulus afforded by the cured polyester network within the ionic domains. The AC impedance fuel cell measurement of the impregnated membrane exhibited an increasing trend of proton conductivity with increasing temperature, which eventually surpassed that of neat Nafion above 100 °C. Of particular importance is that the present paper is the first to successfully incorporate polymer molecules/networks into the Nafion ionic domains by means of impregnation with hyperbranched supramolecules followed by in-situ photopolymerization.

  7. Insights into the Impact of the Nafion Membrane Pretreatment Process on Vanadium Flow Battery Performance.

    Science.gov (United States)

    Jiang, Bo; Yu, Lihong; Wu, Lantao; Mu, Di; Liu, Le; Xi, Jingyu; Qiu, Xinping

    2016-05-18

    Nafion membranes are now the most widely used membranes for long-life vanadium flow batteries (VFBs) because of their extremely high chemical stability. Today, the type of Nafion membrane that should be selected and how to pretreat these Nafion membranes have become critical issues, which directly affects the performance and cost of VFBs. In this work, we chose the Nafion 115 membrane to investigate the effect of the pretreatment process (as received, wet, boiled, and boiled and dried) on the performance of VFBs. The relationship between the nanostructure and transport properties of Nafion 115 membranes is elucidated by wide-angle X-ray diffraction and small-angle X-ray scattering techniques. The self-discharge process, battery efficiencies, electrolyte utilization, and long-term cycling stability of VFBs with differently pretreated Nafion membranes are presented comprehensively. An online monitoring system is used to monitor the electrolyte volume that varies during the long-term charge-discharge test of VFBs. The capacity fading mechanism and electrolyte imbalance of VFBs with these Nafion 115 membranes are also discussed in detail. The optimal pretreatment processes for the benchmark membrane and practical application are synthetically selected.

  8. Effects of Nafion loading in anode catalyst inks on the miniature direct formic acid fuel cell

    Science.gov (United States)

    Morgan, Robert D.; Haan, John L.; Masel, Richard I.

    Nafion, within the anode and cathode catalyst layers, plays a large role in the performance of fuel cells, especially during the operation of the direct formic acid fuel cell (DFAFC). Nafion affects the proton transfer in the catalyst layers of the fuel cell, and studies presented here show the effects of three different Nafion loadings, 10 wt.%, 30 wt.% and 50 wt.%. Short term voltage-current measurements using the three different loadings show that 30 wt.% Nafion loading in the anode shows the best performance in the miniature, passive DFAFC. Nafion also serves as a binder to help hold the catalyst nanoparticles onto the proton exchange membrane (PEM). The DFAFC anode temporarily needs to be regenerated by raising the anode potential to around 0.8 V vs. RHE to oxidize CO bound to the surface, but the Pourbaix diagram predicts that Pd will corrode at these potentials. We found that an anode loading of 30 wt.% Nafion showed the best stability, of the three Nafion loadings chosen, for reducing the amount of loss of electrochemically active area due to high regeneration potentials. Only 58% of the area was lost after 600 potential cycles in formic acid compared to 96 and 99% for 10 wt.% and 50 wt.% loadings, respectively. Lastly we present cyclic voltammetry data that suggest that the Nafion adds to the production of CO during oxidation of formic acid for 12 h at 0.3 V vs. RHE. The resulting data showed that an increase in CO coverage was observed with increasing Nafion content in the anode catalyst layer.

  9. 塑料表面载银微凝胶层层组装膜的制备及抗菌活性%Layer-by-layer Assembled Microgel Films Containing Silver Nanoparticles as Antimicrobial Coatings on Plastics

    Institute of Scientific and Technical Information of China (English)

    刘峰; 王旭; 叶开其; 裘令瑛; 沈家骢

    2011-01-01

    以载银聚烯丙基胺盐酸盐-葡聚糖微凝胶与聚苯乙烯磺酸钠为构筑基元,利用层层组装技术制备了一种可直接沉积在疏水的塑料基底表面的载银抗菌微凝胶膜.研究结果表明,该载银抗菌微凝胶膜具有很好的抗菌能力,并且其抗菌活性可以通过控制载银微凝胶膜的组装层数进行调控.这种沉积在塑料表面的载银抗菌微凝胶膜具有良好的稳定性和基底黏附力,能够保障其长效抗菌性.%Antimicrobial coatings on hydrophobic plastic surfaces were directly fabricated by layer-by-layer deposition of cross-linked poly( allylamine hydrochloride) and dextran microgels containing silver nanoparticles ( Ag@ PAH-D) with poly ( sodium 4-styrenesulfonate) (PSS). The as-prepared Ag@ PAH-D/PSS microgel films are effective in prohibiting the growth of Escherichia coli. The antimicrobial activity of the coatings can be easily controlled by tailoring the number of coating deposition cycles. The antimicrobial coatings of Ag@ PAH-D/PSS microgel films are stable and have satisfactory adhesion to the underlying plastic substrates,which guarantee the long-term application of the coatings.

  10. Comparison of the bacterial removal performance of silver nanoparticles and a polymer based quaternary amine functiaonalized silsesquioxane coated point-of-use ceramic water filters.

    Science.gov (United States)

    Zhang, Hongyin; Oyanedel-Craver, Vinka

    2013-09-15

    This study compares the disinfection performance of ceramic water filters impregnated with two antibacterial compounds: silver nanoparticles and a polymer based quaternary amine functiaonalized silsesquioxane (poly(trihydroxysilyl) propyldimethyloctadecyl ammonium chloride (TPA)). This study evaluated these compounds using ceramic disks manufactures with clay obtained from a ceramic filter factory located in San Mateo Ixtatan, Guatemala. Instead of using full size ceramic water filters, manufactured 6.5 cm diameter ceramic water filter disks were used. Results showed that TPA can achieve a log bacterial reduction value of 10 while silver nanoparticles reached up to 2 log reduction using a initial concentration of bacteria of 10(10)-10(11)CFU/ml. Similarly, bacterial transport demonstrated that ceramic filter disks painted with TPA achieved a bacterial log reduction value of 6.24, which is about 2 log higher than the values obtained for disks painted with silver nanoparticles (bacterial log reduction value: 4.42). The release of both disinfectants from the ceramic materials to the treated water was determined measuring the effluent concentrations in each test performed. Regarding TPA, about 3% of the total mass applied to the ceramic disks was released in the effluent over 300 min, which is slightly lower than the release percentage for silver nanoparticles (4%). This study showed that TPA provides a comparable disinfection performance than silver nanoparticles in ceramic water filter. Another advantage of using TPA is the cost as the price of TPA is considerable lower than silver nanoparticles. In spite of the use of TPA in several medical related products, there is only partial information regarding the health risk associated with the ingestion of this compound. Additional long-term toxicological information for TPA should be evaluated before its future application in ceramic water filters.

  11. Modification of Nafion Membranes by IL-Cation Exchange: Chemical Surface, Electrical and Interfacial Study

    Directory of Open Access Journals (Sweden)

    V. Romero

    2012-01-01

    A study of time evolution of the impedance curves measured in the system “IL aqueous solution/Nafion-112 membrane/IL aqueous solution” was also performed. This study allows us monitoring the electrical changes associated to the IL-cation incorporation in both the membrane and the membrane/IL solution interface, and it provides supplementary information on the characteristic of the Nafion/DTA+ hybrid material. Moreover, the results also show the significant effect of water on the electrical resistance of the Nafion-112/IL-cation-modified membrane.

  12. Specific features of single-pulse femtosecond laser micron and submicron ablation of a thin silver film coated with a micron-thick photoresist layer

    Energy Technology Data Exchange (ETDEWEB)

    Zayarnyi, D A; Ionin, A A; Kudryashov, S I; Makarov, S V; Rudenko, A A [P N Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Drozdova, E A; Odinokov, S B [N.E. Bauman Moscow State Technical University, Moscow (Russian Federation)

    2015-05-31

    Specific features of ablation of a thin silver film with a 1-μm-thick layer of a highly transparent photoresist and the same film without a photoresist layer under single tightly focused femtosecond laser pulses in the visible range (515 nm) are experimentally investigated. Interference effects of internal modification of the photoresist layer, its spallation ablation from the film surface and formation of through hollow submicron channels in the resist without its spallation but with ablation of the silver film lying under the resist are found and discussed. (extreme light fields and their applications)

  13. Microwave-assisted deposition of silver nanoparticles on bamboo pulp fabric through dopamine functionalization

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Linghui [College