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Sample records for silver ions released

  1. Influence of nano-fiber membranes on the silver ions released from hollow fibers containing silver particles

    Directory of Open Access Journals (Sweden)

    Li Huigai

    2016-01-01

    Full Text Available Polyether sulfone was dissolved into dimethylacetamide with the concentration of 20% to prepare a uniform solution for fabrication of nanofiber membranes by bubble electrospinning technique. Morphologies of the nanofiber film were carried out with a scanning electron microscope. The influence on the silver ions escaped from hollow fiber loaded with silver particles was exerted by using different release liquid. The water molecular clusters obtained from the nanofiber membranes filter can slow down the release of silver ions. However, the effect of slowing was weakened with the time increasing. In the end, the trend of change is gradually consistent with the trend of release of silver ions in the deionized water.

  2. Silver nanoparticles embedded in zeolite membranes: release of silver ions and mechanism of antibacterial action

    Science.gov (United States)

    Nagy, Amber; Harrison, Alistair; Sabbani, Supriya; Munson, Robert S; Dutta, Prabir K; Waldman, W James

    2011-01-01

    Background The focus of this study is on the antibacterial properties of silver nanoparticles embedded within a zeolite membrane (AgNP-ZM). Methods and Results These membranes were effective in killing Escherichia coli and were bacteriostatic against methicillin-resistant Staphylococcus aureus. E. coli suspended in Luria Bertani (LB) broth and isolated from physical contact with the membrane were also killed. Elemental analysis indicated slow release of Ag+ from the AgNP-ZM into the LB broth. The E. coli killing efficiency of AgNP-ZM was found to decrease with repeated use, and this was correlated with decreased release of silver ions with each use of the support. Gene expression microarrays revealed upregulation of several antioxidant genes as well as genes coding for metal transport, metal reduction, and ATPase pumps in response to silver ions released from AgNP-ZM. Gene expression of iron transporters was reduced, and increased expression of ferrochelatase was observed. In addition, upregulation of multiple antibiotic resistance genes was demonstrated. The expression levels of multicopper oxidase, glutaredoxin, and thioredoxin decreased with each support use, reflecting the lower amounts of Ag+ released from the membrane. The antibacterial mechanism of AgNP-ZM is proposed to be related to the exhaustion of antioxidant capacity. Conclusion These results indicate that AgNP-ZM provide a novel matrix for gradual release of Ag+. PMID:21931480

  3. Tuning silver ion release properties in reactively sputtered Ag/TiOx nanocomposites

    Science.gov (United States)

    Xiong, J.; Ghori, M. Z.; Henkel, B.; Strunskus, T.; Schürmann, U.; Deng, M.; Kienle, L.; Faupel, F.

    2017-07-01

    Silver/titania nanocomposites with strong bactericidal effects and good biocompatibility/environmental safety show a high potential for antibacterial applications. Tailoring the silver ion release is thus highly promising to optimize the antibacterial properties of such coatings and to preserve biocompatibility. Reactive sputtering is a fast and versatile method for the preparation of such Ag/TiOx nanocomposites coatings. The present work is concerned with the influence of sputter parameters on the surface morphology and silver ion release properties of reactively sputtered Ag/TiOx nanocomposites coatings showing a silver nanoparticle size distribution in the range from 1 to 20 nm. It is shown that the silver ion release rate strongly depends on the total pressure: the coatings prepared at lower pressure present a lower but long-lasting release behavior. The much denser structure produced under these conditions reduces the transport of water molecules into the coating. In addition, the influence of microstructure and thickness of titanium oxide barriers on the silver ion release were investigated intensively. Moreover, for the coatings prepared at high total pressure, it was demonstrated that stable and long-lasting silver release can be achieved by depositing a barrier with a high rate. Nanocomposites produced under these conditions show well controllable silver ion release properties for applications as antibacterial coatings.

  4. Silver release and antimicrobial properties of PMMA films doped with silver ions, nano-particles and complexes

    Energy Technology Data Exchange (ETDEWEB)

    Lyutakov, O., E-mail: lyutakoo@vscht.cz [Department of Solid State Engineering, Institute of Chemical Technology, Prague (Czech Republic); Goncharova, I. [Department of Analytical Chemistry, Institute of Chemical Technology, Prague (Czech Republic); Rimpelova, S. [Department of Biochemistry and Microbiology, Institute of Chemical Technology, Prague (Czech Republic); Kolarova, K.; Svanda, J.; Svorcik, V. [Department of Solid State Engineering, Institute of Chemical Technology, Prague (Czech Republic)

    2015-04-01

    Materials prepared on the base of bioactive silver compounds have become more and more popular due to low microbial resistance to silver. In the present work, the efficiency of polymethylmethacrylate (PMMA) thin films doped with silver ions, nanoparticles and silver–imidazole polymer complex was studied by a combination of AAS, XPS and AFM techniques. The biological activities of the proposed materials were discussed in view of the rate of silver releasing from the polymer matrix. Concentrations of Ag active form were estimated by its ability to interact with L-cysteine using electronic circular dichroism spectroscopy. Rates of the released silver were compared with the biological activity in dependence on the form of embedded silver. Antimicrobial properties of doped polymer films were studied using two bacterial strains: Staphylococcus epidermidis and Escherichia coli. It was found that PMMA films doped with Ag{sup +} had greater activity than those doped with nanoparticles and silver–imidazole polymeric complexes. However, the antimicrobial efficiency of Ag{sup +} doped films was only short-term. Contrary, the antimicrobial activity of silver–imidazole/PMMA films increased in time of sample soaking. - Highlights: • PMMA thin films doped with silver ions, nanoparticles (AgNPs) and silver–imidazole helical complexes (AgIm) were studied. • Silver release from doped polymer films and its biological activity were estimated. • Antimicrobial properties of doped polymer films were also studied. • Ag ions doped films showed the strongest antimicrobial activity, which quickly disappeared. • AgIm and AgNPs doped films showed more stable antimicrobial properties. • AgIm complexes conserve their structure after addition into polymer and after leaching.

  5. Silver release and antimicrobial properties of PMMA films doped with silver ions, nano-particles and complexes

    International Nuclear Information System (INIS)

    Lyutakov, O.; Goncharova, I.; Rimpelova, S.; Kolarova, K.; Svanda, J.; Svorcik, V.

    2015-01-01

    Materials prepared on the base of bioactive silver compounds have become more and more popular due to low microbial resistance to silver. In the present work, the efficiency of polymethylmethacrylate (PMMA) thin films doped with silver ions, nanoparticles and silver–imidazole polymer complex was studied by a combination of AAS, XPS and AFM techniques. The biological activities of the proposed materials were discussed in view of the rate of silver releasing from the polymer matrix. Concentrations of Ag active form were estimated by its ability to interact with L-cysteine using electronic circular dichroism spectroscopy. Rates of the released silver were compared with the biological activity in dependence on the form of embedded silver. Antimicrobial properties of doped polymer films were studied using two bacterial strains: Staphylococcus epidermidis and Escherichia coli. It was found that PMMA films doped with Ag + had greater activity than those doped with nanoparticles and silver–imidazole polymeric complexes. However, the antimicrobial efficiency of Ag + doped films was only short-term. Contrary, the antimicrobial activity of silver–imidazole/PMMA films increased in time of sample soaking. - Highlights: • PMMA thin films doped with silver ions, nanoparticles (AgNPs) and silver–imidazole helical complexes (AgIm) were studied. • Silver release from doped polymer films and its biological activity were estimated. • Antimicrobial properties of doped polymer films were also studied. • Ag ions doped films showed the strongest antimicrobial activity, which quickly disappeared. • AgIm and AgNPs doped films showed more stable antimicrobial properties. • AgIm complexes conserve their structure after addition into polymer and after leaching

  6. Surface ligand controls silver ion release of nanosilver and its antibacterial activity against Escherichia coli

    Directory of Open Access Journals (Sweden)

    Long Y

    2017-04-01

    Full Text Available Yan-Min Long,1,2 Li-Gang Hu,1,3 Xue-Ting Yan,1,3 Xing-Chen Zhao,1,3 Qun-Fang Zhou,1,3 Yong Cai,2,4 Gui-Bin Jiang1,3 1State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Beijing, China; 2Institute of Environment and Health, Jianghan University, Wuhan, Hubei, China; 3College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China; 4Department of Chemistry and Biochemistry, Southeast Environmental Research Center, Florida International University, Miami, FL, USA Abstract: Understanding the mechanism of nanosilver-dependent antibacterial activity against microorganisms helps optimize the design and usage of the related nanomaterials. In this study, we prepared four kinds of 10 nm-sized silver nanoparticles (AgNPs with dictated surface chemistry by capping different ligands, including citrate, mercaptopropionic acid, mercaptohexanoic acid, and mercaptopropionic sulfonic acid. Their surface-dependent chemistry and antibacterial activities were investigated. Owing to the weak bond to surface Ag, short carbon chain, and low silver ion attraction, citrate-coated AgNPs caused the highest silver ion release and the strongest antibacterial activity against Escherichia coli, when compared to the other tested AgNPs. The study on the underlying antibacterial mechanisms indicated that cellular membrane uptake of Ag, NAD+/NADH ratio increase, and intracellular reactive oxygen species (ROS generation were significantly induced in both AgNP and silver ion exposure groups. The released silver ions from AgNPs inside cells through a Trojan-horse-type mechanism were suggested to interact with respiratory chain proteins on the membrane, interrupt intracellular O2 reduction, and induce ROS production. The further oxidative damages of lipid peroxidation and membrane breakdown caused the lethal effect on E. coli. Altogether, this study demonstrated that AgNPs exerted

  7. Silver-Ion-Exchanged Nanostructured Zeolite X as Antibacterial Agent with Superior Ion Release Kinetics and Efficacy against Methicillin-Resistant Staphylococcus aureus.

    Science.gov (United States)

    Chen, Shaojiang; Popovich, John; Iannuzo, Natalie; Haydel, Shelley E; Seo, Dong-Kyun

    2017-11-15

    As antibiotic resistance continues to be a major public health problem, antimicrobial alternatives have become critically important. Nanostructured zeolites have been considered as an ideal host for improving popular antimicrobial silver-ion-exchanged zeolites, because with very short diffusion path lengths they offer advantages in ion diffusion and release over their conventional microsized zeolite counterparts. Herein, comprehensive studies are reported on materials characteristics, silver-ion release kinetics, and antibacterial properties of silver-ion-exchanged nanostructured zeolite X with comparisons to conventional microsized silver-ion-exchanged zeolite (∼2 μm) as a reference. The nanostructured zeolites are submicrometer-sized aggregates (100-700 nm) made up of primary zeolite particles with an average primary particle size of 24 nm. The silver-ion-exchanged nanostructured zeolite released twice the concentration of silver ions at a rate approximately three times faster than the reference. The material exhibited rapid antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA) with minimum inhibitory concentration (MIC) values ranging from 4 to 16 μg/mL after 24 h exposure in various growth media and a minimum bactericidal concentration (MBC; >99.9% population reduction) of 1 μg/mL after 2 h in water. While high concentrations of silver-ion-exchanged nanostructured zeolite X were ineffective at reducing MRSA biofilm cell viability, efficacy increased at lower concentrations. In consideration of potential medical applications, cytotoxicity of the silver-ion-exchanged nanostructured zeolite X was also investigated. After 4 days of incubation, significant reduction in eukaryotic cell viability was observed only at concentrations 4-16-fold greater than the 24 h MIC, indicating low cytotoxicity of the material. Our results establish silver-ion-exchanged nanostructured zeolites as an effective antibacterial material against dangerous

  8. Antibacterial Behavior of Additively Manufactured Porous Titanium with Nanotubular Surfaces Releasing Silver Ions.

    Science.gov (United States)

    Amin Yavari, S; Loozen, L; Paganelli, F L; Bakhshandeh, S; Lietaert, K; Groot, J A; Fluit, A C; Boel, C H E; Alblas, J; Vogely, H C; Weinans, H; Zadpoor, A A

    2016-07-13

    Additive manufacturing (3D printing) has enabled fabrication of geometrically complex and fully interconnected porous biomaterials with huge surface areas that could be used for biofunctionalization to achieve multifunctional biomaterials. Covering the huge surface area of such porous titanium with nanotubes has been already shown to result in improved bone regeneration performance and implant fixation. In this study, we loaded TiO2 nanotubes with silver antimicrobial agents to equip them with an additional biofunctionality, i.e., antimicrobial behavior. An optimized anodizing protocol was used to create nanotubes on the entire surface area of direct metal printed porous titanium scaffolds. The nanotubes were then loaded by soaking them in three different concentrations (i.e., 0.02, 0.1, and 0.5 M) of AgNO3 solution. The antimicrobial behavior and cell viability of the developed biomaterials were assessed. As far as the early time points (i.e., up to 1 day) are concerned, the biomaterials were found to be extremely effective in preventing biofilm formation and decreasing the number of planktonic bacteria particularly for the middle and high concentrations of silver ions. Interestingly, nanotubes not loaded with antimicrobial agents also showed significantly smaller numbers of adherent bacteria at day 1, which may be attributed to the bactericidal effect of high aspect ratio nanotopographies. The specimens with the highest concentrations of antimicrobial agents adversely affected cell viability at day 1, but this effect is expected to decrease or disappear in the following days as the rate of release of silver ions was observed to markedly decrease within the next few days. The antimicrobial effects of the biomaterials, particularly the ones with the middle and high concentrations of antimicrobial agents, continued until 2 weeks. The potency of the developed biomaterials in decreasing the number of planktonic bacteria and hindering the formation of biofilms make

  9. The Antimicrobial Properties of Silver Nanoparticles in Bacillus subtilis Are Mediated by Released Ag+ Ions

    Science.gov (United States)

    Hsueh, Yi-Huang; Lin, Kuen-Song; Ke, Wan-Ju; Hsieh, Chien-Te; Chiang, Chao-Lung; Tzou, Dong-Ying; Liu, Shih-Tung

    2015-01-01

    The superior antimicrobial properties of silver nanoparticles (Ag NPs) are well-documented, but the exact mechanisms underlying Ag-NP microbial toxicity remain the subject of intense debate. Here, we show that Ag-NP concentrations as low as 10 ppm exert significant toxicity against Bacillus subtilis, a beneficial bacterium ubiquitous in the soil. Growth arrest and chromosomal DNA degradation were observed, and flow cytometric quantification of propidium iodide (PI) staining also revealed that Ag-NP concentrations of 25 ppm and above increased membrane permeability. RedoxSensor content analysis and Phag-GFP expression analysis further indicated that reductase activity and cytosolic protein expression decreased in B. subtilis cells treated with 10–50 ppm of Ag NPs. We conducted X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) analyses to directly clarify the valence and fine structure of Ag atoms in B. subtilis cells placed in contact with Ag NPs. The results confirmed the Ag species in Ag NP-treated B. subtilis cells as Ag2O, indicating that Ag-NP toxicity is likely mediated by released Ag+ ions from Ag NPs, which penetrate bacterial cells and are subsequently oxidized intracellularly to Ag2O. These findings provide conclusive evidence for the role of Ag+ ions in Ag-NP microbial toxicity, and suggest that the impact of inappropriately disposed Ag NPs to soil and water ecosystems may warrant further investigation. PMID:26669836

  10. The Antimicrobial Properties of Silver Nanoparticles in Bacillus subtilis Are Mediated by Released Ag+ Ions.

    Directory of Open Access Journals (Sweden)

    Yi-Huang Hsueh

    Full Text Available The superior antimicrobial properties of silver nanoparticles (Ag NPs are well-documented, but the exact mechanisms underlying Ag-NP microbial toxicity remain the subject of intense debate. Here, we show that Ag-NP concentrations as low as 10 ppm exert significant toxicity against Bacillus subtilis, a beneficial bacterium ubiquitous in the soil. Growth arrest and chromosomal DNA degradation were observed, and flow cytometric quantification of propidium iodide (PI staining also revealed that Ag-NP concentrations of 25 ppm and above increased membrane permeability. RedoxSensor content analysis and Phag-GFP expression analysis further indicated that reductase activity and cytosolic protein expression decreased in B. subtilis cells treated with 10-50 ppm of Ag NPs. We conducted X-ray absorption near-edge structure (XANES and extended X-ray absorption fine structure (EXAFS analyses to directly clarify the valence and fine structure of Ag atoms in B. subtilis cells placed in contact with Ag NPs. The results confirmed the Ag species in Ag NP-treated B. subtilis cells as Ag2O, indicating that Ag-NP toxicity is likely mediated by released Ag+ ions from Ag NPs, which penetrate bacterial cells and are subsequently oxidized intracellularly to Ag2O. These findings provide conclusive evidence for the role of Ag+ ions in Ag-NP microbial toxicity, and suggest that the impact of inappropriately disposed Ag NPs to soil and water ecosystems may warrant further investigation.

  11. The release properties of silver ions from Ag-nHA/TiO{sub 2}/PA66 antimicrobial composite scaffolds

    Energy Technology Data Exchange (ETDEWEB)

    Wu Xia; Li Jidong; Wang Li; Huang Di; Zuo Yi; Li Yubao, E-mail: nic7504@scu.edu.c [Research Center for Nano-Biomaterials, Analytical and Testing Center, Sichuan University, Chengdu 610064 (China)

    2010-08-01

    Implant-associated bacterial infection can jeopardize the clinical success of implants and result in loss of supporting bone. The purpose of this study was to develop a novel porous scaffold with long-term antibacterial activity for bone repair or regeneration. Porous nano-hydroxyapatite/titania/polyamide66 scaffolds containing different amounts of silver ions (Ag-nHA/TiO{sub 2}/PA66) were prepared by a phase inversion technique. The release of silver ions from the porous scaffolds in simulated body fluid (SBF) and in the F12 cell culture medium was evaluated via atomic absorption spectrometry. The results showed that the release of Ag{sup +} was time and concentration dependent, increasing with the immersion time and the silver content in the scaffolds. On the other hand, the release property of Ag{sup +} was also influenced by the immersion medium. The cumulative Ag{sup +} release in the F12 medium with time increase parabolically, different from the linear increase or the zero-order release kinetics in the SBF medium. Compared to the slight fluctuation of the Ag{sup +} release rate in SBF during the whole immersion period, the initial fast release rate and the later sustained release rate of Ag{sup +} in the F12 medium could be more helpful for preventing implant-associated infection. Since the Ag-nHA/TiO{sub 2} particles were embedded in the PA66 matrix, the long-term-sustained release should be related both to the relaxation of PA macromolecular chains due to the penetration of water and to the slow release of the substituted Ag{sup +} ions in the HA lattice. The sustained Ag{sup +} release with time indicates that the composite scaffold is suitable for a long-term antimicrobial application during the scaffold-assisted bone repair or regeneration.

  12. The Effect of Annealing at 15000C on Migration and Release of Ion Implanted Silver in CVD Silicon Carbide

    International Nuclear Information System (INIS)

    HJ MacLean; RG Ballinger; LE Kolaya; SA Simonson; N Lewis; M Hanson

    2004-01-01

    The transport of silver in CVD β-SiC has been studied using ion implantation. Silver ions were implanted in β-SiC using the ATLAS accelerator facility at the Argonne National Laboratory. Ion beams with energies of 93 and 161 MeV were used to achieve deposition with peak concentrations at depths of approximately 9 and 13 (micro)m, respectively. As-implanted samples were then annealed at 1500 C for 210 or 480 hours. XPS, SEM, TEM, STEM, and optical methods were used to analyze the material before and after annealing. Silver concentration profiles were determined using XPS before and after annealing. STEM and SEM equipped with quantitative chemical analysis capability were used to more fully characterize the location and morphology of the silver before and after annealing. The results show that, within the uncertainty of measurement techniques, there is no silver migration, via either inter- or intragrannular paths, for the times and temperature studied. Additionally, the silver was observed to phase separate within the SiC after annealing. The irradiation damage from the implantation process resulted in a three-layer morphology in the as-implanted condition: (1) a layer of unaltered SiC, followed by (2) a layer of crystallized SiC, followed by (3) an amorphized layer which contained essentially all of the implanted silver. After annealing the layer structure changed. Layer 1 was unaltered. The grains in layer 2 recrystallized to form an epitaxial (columnar) layer. Layer 3 recrystallized to form a fine grain equiaxed layer. The results of this work do not support the long held assumption that silver release from CVD SiC, used for gas-reactor coated particle fuel, is dominated by grain boundary diffusion

  13. Silver release from nanocomposite Ag/alginate hydrogels in the presence of chloride ions: experimental results and mathematical modeling

    Energy Technology Data Exchange (ETDEWEB)

    Kostic, Danijela, E-mail: dkostic@tmf.bg.ac.rs [Innovation Center of the Faculty of Technology and Metallurgy (Serbia); Vidovic, Srđan, E-mail: srdjanhi@gmail.com; Obradovic, Bojana, E-mail: bojana@tmf.bg.ac.rs [University of Belgrade, Faculty of Technology and Metallurgy (Serbia)

    2016-03-15

    A stepwise experimental and mathematical modeling approach was used to assess silver release from nanocomposite Ag/alginate microbeads in wet and dried forms into water and into normal saline solution chosen as a simplified model for certain biological fluids (e.g., blood plasma, wound exudates, sweat, etc). Three phenomena were connected and mathematically described: diffusion of silver nanoparticles (AgNPs) within the alginate hydrogel, AgNP oxidation/dissolution and reaction with chloride ions, and diffusion of the resultant silver-chloride species. Mathematical modeling results agreed well with the experimental data with the AgNP diffusion coefficient estimated as 1.3 × 10{sup −18} m{sup 2} s{sup −1}, while the first-order kinetic rate constant of AgNP oxidation/dissolution and diffusivity of silver-chloride species were shown to be inversely related. In specific, rapid rehydration and swelling of dry Ag/alginate microbeads induced fast AgNP oxidation/dissolution reaction with Cl{sup −} and AgCl precipitation within the microbeads with the lowest diffusivity of silver-chloride species compared to wet microbeads in normal saline. The proposed mathematical model provided an insight into the phenomena related to silver release from nanocomposite Ca-alginate hydrogels relevant for use of antimicrobial devices and established, at the same time, a basis for further in-depth studies of AgNP interactions in hydrogels in the presence of chloride ions.

  14. Both released silver ions and particulate Ag contribute to the toxicity of AgNPs to earthworm Eisenia fetida

    NARCIS (Netherlands)

    Li, L.; , van, Gestel C.A.M.

    2015-01-01

    To disentangle the contribution of ionic and nanoparticulate Ag to the overall toxicity to the earthworm Eisenia fetida, a semi-permeable membrane strategy was used to separate Ag+ released from silver nanoparticles (AgNPs) in an aqueous exposure. Internal Ag fractionation, activities of antioxidant

  15. Production of silver ions from colloidal silver by nanoparticle iontophoresis system.

    Science.gov (United States)

    Tseng, Kuo-Hsiung; Liao, Chih-Yu

    2011-03-01

    Metal ions, especially the silver ion, were used to treat infection before the initiation of antibiotic therapy. Unfortunately, there is a lack of research on the metallic nanoparticle suspension as a reservoir for metal ion release application. For medical purposes, conversion of colloidal silver into an ionic form is necessary, but not using silver salts (e.g., AgNO3, Ag2SO4), due to the fact that the counter-ion of silver salts may cause problems to the body as the silver ion (Ag+) is consumed. The goal of this research is to develop a silver nanoparticle iontophoresis system (NIS) which can provide a relatively safe bactericidal silver ion solution with a controllable electric field. In this study, ion-selective electrodes were used to identify and observe details of the system's activity. Both qualitative and quantitative data analyses were performed. The experimental results show that the ion releasing peak time (R(PT)) has an inversely proportional relationship with the applied current and voltage. The ion releasing maximum level (R(ML)) and dosage (R(D)) are proportional to the current density and inversely proportional to the voltage, respectively. These results reveal that the nanoparticle iontophoresis system (NIS) is an alternative method for the controlled release of a metal ion and the ion's concentration profile, by controlling the magnitude of current density (1 microA/cm2 equal to 1 ppm/hour) and applied voltage.

  16. Bacterial inhibiting surfaces caused by the effects of silver release and/or electrical field

    DEFF Research Database (Denmark)

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

    2008-01-01

    In this study, silver-palladium surfaces and silver-bearing stainless steels were designed and investigated focusing on electrochemical principles to form inhibiting effects on planktonic and/or biofilm bacteria in water systems. Silver-resistant Escherichia coli and silver-sensitive E. coli were...... silver ions release can occur from their Surfaces. For silver-bearing stainless steels, the inhibiting effect can only be explained by high local silver ions release. and can be limited or deactivated dependent on the specific environment. (c) 2008 Elsevier Ltd. All rights reserved....

  17. Oral toxicity of silver ions, silver nanoparticles and colloidal silver – a review

    DEFF Research Database (Denmark)

    Hadrup, Niels; Lam, Henrik Rye

    2014-01-01

    Orally administered silver has been described to be absorbed in a range of 0.4-18% in mammals with a human value of 18%. Based on findings in animals, silver seems to be distributed to all of the organs investigated, with the highest levels being observed in the intestine and stomach. In the skin......, silver induces a blue-grey discoloration termed argyria. Excretion occurs via the bile and urine. The following dose-dependent animal toxicity findings have been reported: death, weight loss, hypoactivity, altered neurotransmitter levels, altered liver enzymes, altered blood values, enlarged hearts...... and immunological effects. Substantial evidence exists suggesting that the effects induced by particulate silver are mediated via silver ions that are released from the particle surface. With the current data regarding toxicity and average human dietary exposure, a Margin of Safety calculation indicates at least...

  18. Use of a silver ion selective electrode to assess mechanisms responsible for biological effects of silver nanoparticles

    International Nuclear Information System (INIS)

    Koch, Marcus; Kiefer, Silke; Cavelius, Christian; Kraegeloh, Annette

    2012-01-01

    For a detailed analysis of the biological effects of silver nanoparticles, discrimination between effects related to the nano-scale size of the particles and effects of released silver ions is required. Silver ions are either present in the initial particle dispersion or released by the nanoparticles over time. The aim of this study is to monitor the free silver ion activity {Ag + } in the presence of silver nanoparticles using a silver ion selective electrode. Therefore, silver in the form of silver nanoparticles, 4.2 ± 1.4 nm and 2–30 nm in size, or silver nitrate was added to cell culture media in the absence or presence of A549 cells as a model for human type II alveolar epithelial cells. The free silver ion activity measured after the addition of silver nanoparticles was determined by the initial ionic silver content. The p {Ag + } values indicated that the cell culture media decrease the free silver ion activity due to binding of silver ions by constituents of the media. In the presence of A549 cells, the free silver ion activity was further reduced. The morphology of A549 cells, cultivated in DME medium containing 9.1% (v/v) FBS, was affected by adding AgNO 3 at concentrations of ≥30 μM after 24 h. In comparison, silver nanoparticles up to a concentration of 200 μM Ag did not affect cellular morphology. Our experiments indicate that the effect of silver nanoparticles is mainly mediated by silver ions. An effect of silver on cellular morphology was observed at p {Ag + } ≤ 9.2.

  19. 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 (food), the addition of a 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 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. Copyright © 2013 Elsevier B.V. All rights reserved.

  20. Oral toxicity of silver ions, silver nanoparticles and colloidal silver--a review.

    Science.gov (United States)

    Hadrup, Niels; Lam, Henrik R

    2014-02-01

    Orally administered silver has been described to be absorbed in a range of 0.4-18% in mammals with a human value of 18%. Based on findings in animals, silver seems to be distributed to all of the organs investigated, with the highest levels being observed in the intestine and stomach. In the skin, silver induces a blue-grey discoloration termed argyria. Excretion occurs via the bile and urine. The following dose-dependent animal toxicity findings have been reported: death, weight loss, hypoactivity, altered neurotransmitter levels, altered liver enzymes, altered blood values, enlarged hearts and immunological effects. Substantial evidence exists suggesting that the effects induced by particulate silver are mediated via silver ions that are released from the particle surface. With the current data regarding toxicity and average human dietary exposure, a Margin of Safety calculation indicates at least a factor of five before a level of concern to the general population is reached. Copyright © 2013 Elsevier Inc. All rights reserved.

  1. Release of silver nanoparticles from outdoor facades

    International Nuclear Information System (INIS)

    Kaegi, Ralf; Sinnet, Brian; Zuleeg, Steffen; Hagendorfer, Harald; Mueller, Elisabeth; Vonbank, Roger; Boller, Markus; Burkhardt, Michael

    2010-01-01

    In this study we investigate the release of metallic silver nanoparticles (Ag-NP) from paints used for outdoor applications. A facade panel mounted on a model house was exposed to ambient weather conditions over a period of one year. The runoff volume of individual rain events was determined and the silver and titanium concentrations of 36 out of 65 runoff events were measured. Selected samples were prepared for electron microscopic analysis. A strong leaching of the Ag-NP was observed during the initial runoff events with a maximum concentration of 145 μ Ag/l. After a period of one year, more than 30% of the Ag-NP were released to the environment. Particles were mostly 2 S. - We provide direct evidence for the release of silver nanoparticles from exterior paints to the aquatic environment.

  2. Characterization and antibacterial properties of porous fibers containing silver ions

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Zhaoyang; Fan, Chenxu; Tang, Xiaopeng; Zhao, Jianghui; Song, Yanhua; Shao, Zhongbiao [National Engineering Laboratory for Modern Silk, College of Textile and Engineering, Soochow University, 199 Ren-ai Road, Suzhou 215123 (China); Xu, Lan, E-mail: lanxu@suda.edu.cn [National Engineering Laboratory for Modern Silk, College of Textile and Engineering, Soochow University, 199 Ren-ai Road, Suzhou 215123 (China); Nantong Textile Institute of Soochow University, 58 Chong-chuan Road, Nantong 226018 (China)

    2016-11-30

    Highlights: • Antibacterial electrospun PLA porous fibers containing silver ions were prepared. • Porous structure and porosity of PLA/Ag{sup +} porous fibers were investigated. • The antibacterial effects of PLA/Ag{sup +} porous fibers were studied. • The released mechanism of silver ions in the porous fibers was illustrated. • The porous structure could improve the antibacterial properties. - Abstract: Materials prepared on the base of bioactive silver compounds have become more and more popular. In the present work, the surface morphology, structure and properties, of electrospun Polylactide Polylactic acid (PLA) porous fibers containing various ratios of silver ions were investigated by a combination of X-ray photoelectron spectroscopy (XPS), universal testing machine, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and et al. The biological activities of the proposed porous fibers were discussed in view of the released silver ions concentration. Antibacterial properties of these porous fibers were studied using two bacterial strains: Escherichia coli (E. coli) and Methicillin-resistant Staphylococcus aureus (MRSA). Results of the antibacterial testing suggested that PLA porous fibers containing silver ions could be used as potent antibacterial wound dressing materials in the biomedical field.

  3. Characterization and antibacterial properties of porous fibers containing silver ions

    International Nuclear Information System (INIS)

    Sun, Zhaoyang; Fan, Chenxu; Tang, Xiaopeng; Zhao, Jianghui; Song, Yanhua; Shao, Zhongbiao; Xu, Lan

    2016-01-01

    Highlights: • Antibacterial electrospun PLA porous fibers containing silver ions were prepared. • Porous structure and porosity of PLA/Ag + porous fibers were investigated. • The antibacterial effects of PLA/Ag + porous fibers were studied. • The released mechanism of silver ions in the porous fibers was illustrated. • The porous structure could improve the antibacterial properties. - Abstract: Materials prepared on the base of bioactive silver compounds have become more and more popular. In the present work, the surface morphology, structure and properties, of electrospun Polylactide Polylactic acid (PLA) porous fibers containing various ratios of silver ions were investigated by a combination of X-ray photoelectron spectroscopy (XPS), universal testing machine, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and et al. The biological activities of the proposed porous fibers were discussed in view of the released silver ions concentration. Antibacterial properties of these porous fibers were studied using two bacterial strains: Escherichia coli (E. coli) and Methicillin-resistant Staphylococcus aureus (MRSA). Results of the antibacterial testing suggested that PLA porous fibers containing silver ions could be used as potent antibacterial wound dressing materials in the biomedical field.

  4. Silver release from coated particle fuel

    International Nuclear Information System (INIS)

    Brown, P.E.; Nabielek, H.

    1977-03-01

    The fission product Ag-110 m released from coated particles can be the dominant source of radioactivity from the core of a high temperature reactor in the early stages of the reactor life and possibly limits the accessability of primary circuit components. It can be shown that silver is retained in oxide fuel by a diffusion process (but not in carbide or carbon-diluted fuel) and that silver is released through all types of pyrocarbon layers. The retention in TRISO particles is variable and seems to be mainly connected with operating temperature and silicon carbide quality. (orig.) [de

  5. Electrolytic silver ion cell sterilizes water supply

    Science.gov (United States)

    Albright, C. F.; Gillerman, J. B.

    1968-01-01

    Electrolytic water sterilizer controls microbial contamination in manned spacecraft. Individual sterilizer cells are self-contained and require no external power or control. The sterilizer generates silver ions which do not impart an unpleasant taste to water.

  6. Photochemical Study of Silver Nanoparticles Formed from the Reduction of Silver Ions by Humic Acid

    Science.gov (United States)

    Leslie, Renee M.

    This study focuses on the ability of silver ions and humic acid to form silver nanoparticles in the presence of UV and visible light. Silver nanoparticles have a number of industrial applications due primarily to their antimicrobial properties, but these properties pose an environmental threat. Silver nanoparticles can directly disrupt sensitive ecosystems by harming bacteria. Consumption of silver nanoparticles results in silver ions and silver nanoparticles entering waterways; the presence of silver ions raises the question of whether nanoparticles can reform in environmental waters. As our data show, silver nanoparticles can form from the reduction of silver ions by humic acid after irradiation with UV and visible light. In order to better understand the mechanism of these naturally synthesized silver nanoparticles, we investigated the effects of reactant concentration, experimental conditions and presence of ions/reactive species. We monitored silver nanoparticle growth with UV-visible spectroscopy. The evolution in time of nanoparticle size was monitored by dynamic light scattering (DLS).

  7. Electrosorption of tetraalkylammonium ions on silver iodide

    NARCIS (Netherlands)

    Keizer, de A.

    1981-01-01

    The object of the present investigations was to study the ef fect of the adsorption of charged organic ions on electrically charged, solid-liquid interfaces. To that end, symmetrical quater nary ammonium ions were adsorbed on a silver iodide-electrolyte interface at various

  8. Release and antimicrobial activity of silver sulphadiazine from different creams

    NARCIS (Netherlands)

    Saene, J.J.M.; Trooster, J.F.G.; Meulenhoff, A.M.C.; Lerk, C.F.; Bult, A.

    The release and antimicrobial activity of silver sulphadiazine from five different creams were studied: unguentum emulsilicans aquosum, unguentum hydrophy. licum non ionogenicum, paraffin cream (15 per cent), a homemade preparation and a commercially available preparation (Flamazine). A diffusion

  9. Silver Alginate Hydrogel Micro- and Nanocontainers for Theranostics: Synthesis, Encapsulation, Remote Release, and Detection.

    Science.gov (United States)

    Lengert, Ekaterina; Saveleva, Mariia; Abalymov, Anatolii; Atkin, Vsevolod; Wuytens, Pieter C; Kamyshinsky, Roman; Vasiliev, Alexander L; Gorin, Dmitry A; Sukhorukov, Gleb B; Skirtach, Andre G; Parakhonskiy, Bogdan

    2017-07-05

    We have designed multifunctional silver alginate hydrogel microcontainers referred to as loaded microcapsules with different sizes by assembling them via a template assisted approach using natural, highly porous calcium carbonate cores. Sodium alginate was immobilized into the pores of calcium carbonate particles of different sizes followed by cross-linking via addition of silver ions, which had a dual purpose: on one hand, the were used as a cross-linking agent, albeit in the monovalent form, while on the other hand they have led to formation of silver nanoparticles. Monovalent silver ions, an unusual cross-linking agent, improve the sensitivity to ultrasound, lead to homogeneous distribution of silver nanoparticles. Silver nanoparticles appeared on the shell of the alginate microcapsules in the twin-structure as determined by transmission electron microscopy. Remote release of a payload from alginate containers by ultrasound was found to strongly depend on the particle size. The possibility to use such particles as a platform for label-free molecule detection based on the surface enhanced Raman scattering was demonstrated. Cytotoxicity and cell uptake studies conducted in this work have revealed that microcontainers exhibit nonessential level of toxicity with an efficient uptake of cells. The above-described functionalities constitute building blocks of a theranostic system, where detection and remote release can be achieved with the same carrier.

  10. Understanding long-term silver release from surface modified porous titanium implants.

    Science.gov (United States)

    Shivaram, Anish; Bose, Susmita; Bandyopadhyay, Amit

    2017-08-01

    Prevention of orthopedic device related infection (ODRI) using antibiotics has met with limited amount of success and is still a big concern during post-surgery. As an alternative, use of silver as an antibiotic treatment to prevent surgical infections is being used due to the well-established antimicrobial properties of silver. However, in most cases silver is used in particulate form with wound dressings or with short-term devices such as catheters but not with load-bearing implants. We hypothesize that strongly adherent silver to load-bearing implants can offer longer term solution to infection in vivo. Keeping that in mind, the focus of this study was to understand the long term release study of silver ions for a period of minimum 6months from silver coated surface modified porous titanium implants. Implants were fabricated using a LENS™ system, a powder based additive manufacturing technique, with at least 25% volume porosity, with and without TiO 2 nanotubes in phosphate buffer saline (pH 7.4) to see if the total release of silver ions is within the toxic limit for human cells. Considering the fact that infection sites may reduce the local pH, silver release was also studied in acetate buffer (pH 5.0) for a period of 4weeks. Along with that, the osseointegrative properties as well as cytotoxicity of porous titanium implants were assessed in vivo for a period of 12weeks using a rat distal femur model. In vivo results indicate that porous titanium implants with silver coating show comparable, if not better, biocompatibility and bonding at the bone-implant interface negating any concerns related to toxicity related to silver to normal cells. The current research is based on our recently patented technology, however focused on understanding longer-term silver release to mitigate infection related problems in load-bearing implants that can even arise several months after the surgery. Prevention of orthopedic device related infection using antibiotics has met

  11. Silver distribution and release from an antimicrobial denture base resin containing silver colloidal nanoparticles.

    Science.gov (United States)

    Monteiro, Douglas Roberto; Gorup, Luiz Fernando; Takamiya, Aline Satie; de Camargo, Emerson Rodrigues; Filho, Adhemar Colla Ruvolo; Barbosa, Debora Barros

    2012-01-01

    The aim of this study was to evaluate a denture base resin containing silver colloidal nanoparticles through morphological analysis to check the distribution and dispersion of these particles in the polymer and by testing the silver release in deionized water at different time periods. A Lucitone 550 denture resin was used, and silver nanoparticles were synthesized by reduction of silver nitrate with sodium citrate. The acrylic resin was prepared in accordance with the manufacturers' instructions, and silver nanoparticle suspension was added to the acrylic resin monomer in different concentrations (0.05, 0.5, and 5 vol% silver colloidal). Controls devoid of silver nanoparticles were included. The specimens were stored in deionized water at 37°C for 7, 15, 30, 60, and 120 days, and each solution was analyzed using atomic absorption spectroscopy. Silver was not detected in deionized water regardless of the silver nanoparticles added to the resin and of the storage period. Micrographs showed that with lower concentrations, the distribution of silver nanoparticles was reduced, whereas their dispersion was improved in the polymer. Moreover, after 120 days of storage, nanoparticles were mainly located on the surface of the nanocomposite specimens. Incorporation of silver nanoparticles in the acrylic resin was evidenced. Moreover, silver was not detected by the detection limit of the atomic absorption spectrophotometer used in this study, even after 120 days of storage in deionized water. Silver nanoparticles are incorporated in the PMMA denture resin to attain an effective antimicrobial material to help control common infections involving oral mucosal tissues in complete denture wearers. © 2011 by the American College of Prosthodontists.

  12. Antibacterial activity of nitric oxide releasing silver nanoparticles

    Science.gov (United States)

    Seabra, Amedea B.; Manosalva, Nixson; de Araujo Lima, Bruna; Pelegrino, Milena T.; Brocchi, Marcelo; Rubilar, Olga; Duran, Nelson

    2017-06-01

    Silver nanoparticles (AgNPs) are well known potent antimicrobial agents. Similarly, the free radical nitric oxide (NO) has important antibacterial activity, and due to its instability, the combination of NO and nanomaterials has been applied in several biomedical applications. The aim of this work was to synthesize, characterize and evaluate the antibacterial activity of a new NO-releasing AgNPs. Herein, AgNPs were synthesized by the reduction of silver ions (Ag+) by catechin, a natural polyphenol and potent antioxidant agent, derived from green tea extract. Catechin acts as a reducing agent and as a capping molecule on the surface of AgNPs, minimizing particle agglomeration. The as-synthesized nanoparticles were characterized by different techniques. The results showed the formation of AgNPs with average hydrodynamic size of 44 nm, polydispersity index of 0.21, and zeta potential of -35.9 mV. X-ray diffraction and Fourier transform infrared spectroscopy revealed the presence of the AgNP core and cathecin as capping agent. The low molecular weight mercaptosuccinic acid (MSA), which contain free thiol group, was added on the surface of catechin-AgNPs, leading to the formation of MSA-catechin-AgNPs (the NO precursor nanoparticle). Free thiol groups of MSA-catechin-AgNPs were nitrosated leading to the formation of S-nitroso-mercaptosuccinic acid (S-nitroso-MSA), the NO donor. The amount of 342 ± 16 µmol of NO was released per gram of S-nitroso-MSA-catechin-AgNPs. The antibacterial activities of catechin-AgNPs, MSA-catechin-AgNPs, and S-nitroso-MSA-catechin-AgNPs were evaluated towards different resistant bacterial strains. The results demonstrated an enhanced antibacterial activity of the NO-releasing AgNP. For instance, the minimal inhibitory concentration values for Pseudomonas aeruginosa (ATCC 27853) incubated with AgNPs-catechin, AgNPs-catechin-MSA, and AgNPs-catechin-S-nitroso-MSA were found to be 62, 125 and 3 µg/mL, respectively. While in the case of

  13. USE OF SILVER IONS IN PASTEURIZED MILK PRODUCTION

    Directory of Open Access Journals (Sweden)

    A. Mamaev

    2012-10-01

    Full Text Available The means of pasteurized milk shelf life prolongation by electro-chemical diffusion of silver ions has been introduced. Three samples of pasteurized milk were test subjects. In the course of study the following data have been examined: organoleptic, physicochemical, microbiological parameters of check samples and pilot samples of raw and pasteurized milk. Its shelf life has been determined. It has been determined that the test results of raw and pasteurized milk samples processed by various concentration of silver ions showed minor difference in organoleptic, physic-chemical, microbiological parameters and shelf life span. In this connection it appears reasonable to use the smallest concentration of silver ions - 50 micrograms per liter for milk shelf life prolongation as it is considered the least harmful for person's organism. Infusion of silver ions in the concentration of 50 micrograms per liter allows to prolong raw and pasteurized milk shelf life by two days.

  14. The release of silver nanoparticles from commercial toothbrushes

    DEFF Research Database (Denmark)

    Mackevica, Aiga; Olsson, Mikael Emil; Hansen, Steffen Foss

    2017-01-01

    The use of silver nanoparticles (NPs) in commercial products has become increasingly common in the past decade, mostly due to their antimicrobial properties. Using Ag NP-containing articles may lead to particle release, which raises concern of human and environmental safety. The published...... literature addressing particle release is scarce, especially when it comes to quantifying exposure to NPs specifically. In this study, we have experimentally investigated the release of total Ag and Ag NP from commercially available toothbrushes i.e. biodegradable toothbrushes for adults and toothbrushes...

  15. Stereophotogrammetric study of surface topography in ion irradiated silver

    International Nuclear Information System (INIS)

    Sokolov, V.N.; Fayazov, I.M.

    1993-01-01

    The irradiated surface topography of polycrystalline silver was studied using the stereophotogrammetric method. The surface of silver was irradiated with 30 keV argon ions at variation for the ion incidence angle in interval of 0-80 deg relative to a surface normal. The influence of the inclination angle of the sample in the SEM on the cone shape of a SEM-picture of the irradiated surface is discussed. The parameters of cones on the irradiated surface of silver were measured by the SEM-stereomethod. The measurements of the sample section perpendicular to the incidence plane are also carried out

  16. Release of silver and copper nanoparticles from polyethylene nanocomposites and their penetration into Listeria monocytogenes

    Energy Technology Data Exchange (ETDEWEB)

    Tamayo, L.A., E-mail: laura.tamayo@usach.cl [Departamento de Química de los Materiales, Facultad de Química y Biología, Universidad de Santiago de Chile, Av. L. B. O' Higgins 3363, Casilla 40, Correo 33, Santiago (Chile); Zapata, P.A. [Departamento de Química de los Materiales, Facultad de Química y Biología, Universidad de Santiago de Chile, Av. L. B. O' Higgins 3363, Casilla 40, Correo 33, Santiago (Chile); Grupo de Polímeros, Facultad de Química y Biología, Universidad de Santiago de Chile, Av. L. B. O' Higgins 3363, Casilla 40, Correo 33, Santiago (Chile); Vejar, N.D.; Azócar, M.I.; Gulppi, M.A. [Departamento de Química de los Materiales, Facultad de Química y Biología, Universidad de Santiago de Chile, Av. L. B. O' Higgins 3363, Casilla 40, Correo 33, Santiago (Chile); Zhou, X.; Thompson, G.E. [Corrosion and Protection Centre, School of Materials, The University of Manchester, Manchester, M13 9PL England (United Kingdom); Rabagliati, F.M. [Departamento de Química de los Materiales, Facultad de Química y Biología, Universidad de Santiago de Chile, Av. L. B. O' Higgins 3363, Casilla 40, Correo 33, Santiago (Chile); Grupo de Polímeros, Facultad de Química y Biología, Universidad de Santiago de Chile, Av. L. B. O' Higgins 3363, Casilla 40, Correo 33, Santiago (Chile); and others

    2014-07-01

    Since infection is a major cause of death in a patient whose immune responses have been compromised (immunocompromised patient), considerable attention has been focused on developing materials for the prevention of infections. This has been directed primarily at suppressing or eliminating the host's endogenous microbial burden and decreasing the acquisition of new organisms. In this study, the antibacterial properties of two nanocomposites, polyethylene modified with silver nanoparticles (PE-AgNps) or copper nanoparticles (PE-CuNps), against Listeria monocytogenes have been investigated. In order to elucidate the antibacterial mechanism, specifically whether this mechanism corresponds to bactericidal or bacteriolytic activities, we have determined the extent of release of metal ions (Ag{sup +} and Cu{sup 2+}) and, also, the morphology of the bacteria. The metal ion release from nanocomposites was followed by inductively coupled plasma spectrometry and the morphology of the bacteria was revealed through examination of ultramicrotomed sections of bacteria in a transmission electron microscope. The study of metal ion release from the nanocomposites shows that for both nanocomposites the amount of ions released varies with time, which initially displays a linear behavior until an asymptotic behavior is reached. Further, TEM images show that silver nanoparticles (AgNps) and copper nanoparticles (CuNps), which are released from the nanocomposites, can penetrate to the cell wall and the plasma membrane of bacteria. Resulting morphological changes involve separation of the cytoplasmic membrane from the cell wall, which is known to be an effect of plasmolysis. It was revealed that the antibacterial abilities of the two nanocomposites against L. monocytogenes are associated with both bactericidal and bacteriolytic effects. - Highlights: • Nanocomposites showed excellent antibacterial activity against L. monocytogenes. • The biocide abilities of nanocomposites

  17. Assessing bio-available silver released from silver nanoparticles embedded in silica layers using the green algae Chlamydomonas reinhardtii as bio-sensors

    Energy Technology Data Exchange (ETDEWEB)

    Pugliara, Alessandro [nMat group-CEMES (Centre d' Elaboration de Matériaux et d' Etudes Structurales)-CNRS, Université de Toulouse, 29 rue Jeanne Marvig, BP 94347, F-31055 Toulouse Cedex 4 (France); LAPLACE (LAboratoire PLAsma et Conversion d' Energie), Université de Toulouse, CNRS, UPS, INPT, 118 route de Narbonne, F-31062 Toulouse (France); Makasheva, Kremena; Despax, Bernard [LAPLACE (LAboratoire PLAsma et Conversion d' Energie), Université de Toulouse, CNRS, UPS, INPT, 118 route de Narbonne, F-31062 Toulouse (France); Bayle, Maxime; Carles, Robert; Benzo, Patrizio; BenAssayag, Gérard; Pécassou, Béatrice [nMat group-CEMES (Centre d' Elaboration de Matériaux et d' Etudes Structurales)-CNRS, Université de Toulouse, 29 rue Jeanne Marvig, BP 94347, F-31055 Toulouse Cedex 4 (France); Sancho, Maria Carmen; Navarro, Enrique [IPE (Instituto Pirenaico de Ecología)-CSIC, Avda. Montañana 1005, Zaragoza 50059 (Spain); Echegoyen, Yolanda [I3A, Department of Analytical Chemistry, University of Zaragoza, C/ María de Luna 3, 50018, Zaragoza (Spain); Bonafos, Caroline, E-mail: bonafos@cemes.fr [nMat group-CEMES (Centre d' Elaboration de Matériaux et d' Etudes Structurales)-CNRS, Université de Toulouse, 29 rue Jeanne Marvig, BP 94347, F-31055 Toulouse Cedex 4 (France)

    2016-09-15

    Silver nanoparticles (AgNPs) because of their strong antibacterial activity are widely used in health-care sector and industrial applications. Their huge surface-volume ratio enhances the silver release compared to the bulk material, leading to an increased toxicity for microorganisms sensitive to this element. This work presents an assessment of the toxic effect on algal photosynthesis due to small (size < 20 nm) AgNPs embedded in silica layers. Two physical approaches were originally used to elaborate the nanocomposite structures: (i) low energy ion beam synthesis and (ii) combined silver sputtering and plasma polymerization. These techniques allow elaboration of a single layer of AgNPs embedded in silica films at defined nanometer distances (from 0 to 7 nm) beneath the free surface. The structural and optical properties of the nanostructures were studied by transmission electron microscopy and optical reflectance. The silver release from the nanostructures after 20 h of immersion in buffered water was measured by inductively coupled plasma mass spectrometry and ranges between 0.02 and 0.49 μM. The short-term toxicity of Ag to photosynthesis of Chlamydomonas reinhardtii was assessed by fluorometry. The obtained results show that embedding AgNPs reduces the interactions with the buffered water free media, protecting the AgNPs from fast oxidation. The release of bio-available silver (impacting on the algal photosynthesis) is controlled by the depth at which AgNPs are located for a given host matrix. This provides a procedure to tailor the toxicity of nanocomposites containing AgNPs. - Highlights: • Controlled synthesis of 2D arrays of silver nanoparticles embedded in silica. • Assessing bio-available silver release using the green algae as bio-sensors. • The Ag release can be controlled by the distance nanoparticles/dielectric surface. • All the Ag released in solution is in the form of Ag{sup +} ions. • Toxicity comparable to similar concentrations of

  18. Adhesion of silver films to ion-bombarded alumina

    International Nuclear Information System (INIS)

    Erck, R.A.; Fenske, G.R.

    1990-01-01

    This paper reports on silver films deposited on alumina substrates using ion bombardment. Adhesion strength was measured as a function of deposition conditions, sputter-cleaning time, and bombarding ion species, using a pull-type adhesion tester. Argon- and argon/oxygen-ion sputtering produced large increases in adhesion strength, with the greatest increases occurring for oxygen-ion bombardment. Adhesion strength increased monotonically as a function of ion sputtering time. At a given deposition rate, further enhancement of adhesion is seen with concurrent ion bombardment

  19. DETERMINATION OF METAL IONS RELEASED BY STAINLESS ...

    African Journals Online (AJOL)

    Preferred Customer

    The study indicated that the reused wires released more ions than new ones at all time points. ... recycled brackets released more ions than the new ones, reduction of the pH of artificial saliva resulted in ... Nickel(II) and vanadium(V) reduce.

  20. The release of silver nanoparticles from commercial toothbrushes

    International Nuclear Information System (INIS)

    Mackevica, Aiga; Olsson, Mikael Emil; Hansen, Steffen Foss

    2017-01-01

    Highlights: • Ag and Ag nanoparticle release was measured from two types of toothbrushes. • Maximum release for entire intended product use period was 10 ng Ag per toothbrush. • Released Ag nanoparticles had median sizes from 42 to 47 nm. • Up to 2.8% of total Ag released was detected in nanoparticulate form. - Abstract: The use of silver nanoparticles (NPs) in commercial products has become increasingly common in the past decade, mostly due to their antimicrobial properties. Using Ag NP-containing articles may lead to particle release, which raises concern of human and environmental safety. The published literature addressing particle release is scarce, especially when it comes to quantifying exposure to NPs specifically. In this study, we have experimentally investigated the release of total Ag and Ag NP from commercially available toothbrushes i.e. biodegradable toothbrushes for adults and toothbrushes for children. Toothbrushes were immersed and abraded in tap water for 24 h corresponding to more than the whole intended usage time of a toothbrush. The total amount of released Ag was quantified by inductively coupled plasma—mass spectrometry (ICP-MS) analysis, and the Ag NPs were characterized by single particle ICP-MS and transmission electron microscopy (TEM). The median size of the released Ag NPs ranged from 42 to 47 nm, and the maximum total Ag release was 10.2 ng per toothbrush. The adult toothbrushes were generally releasing more total Ag and NPs than children toothbrushes. In conclusion, our results indicate that the use of Ag NP-impregnated toothbrushes can cause consumer as well as environmental exposure to Ag NPs.

  1. The release of silver nanoparticles from commercial toothbrushes

    Energy Technology Data Exchange (ETDEWEB)

    Mackevica, Aiga, E-mail: aima@env.dtu.dk; Olsson, Mikael Emil; Hansen, Steffen Foss

    2017-01-15

    Highlights: • Ag and Ag nanoparticle release was measured from two types of toothbrushes. • Maximum release for entire intended product use period was 10 ng Ag per toothbrush. • Released Ag nanoparticles had median sizes from 42 to 47 nm. • Up to 2.8% of total Ag released was detected in nanoparticulate form. - Abstract: The use of silver nanoparticles (NPs) in commercial products has become increasingly common in the past decade, mostly due to their antimicrobial properties. Using Ag NP-containing articles may lead to particle release, which raises concern of human and environmental safety. The published literature addressing particle release is scarce, especially when it comes to quantifying exposure to NPs specifically. In this study, we have experimentally investigated the release of total Ag and Ag NP from commercially available toothbrushes i.e. biodegradable toothbrushes for adults and toothbrushes for children. Toothbrushes were immersed and abraded in tap water for 24 h corresponding to more than the whole intended usage time of a toothbrush. The total amount of released Ag was quantified by inductively coupled plasma—mass spectrometry (ICP-MS) analysis, and the Ag NPs were characterized by single particle ICP-MS and transmission electron microscopy (TEM). The median size of the released Ag NPs ranged from 42 to 47 nm, and the maximum total Ag release was 10.2 ng per toothbrush. The adult toothbrushes were generally releasing more total Ag and NPs than children toothbrushes. In conclusion, our results indicate that the use of Ag NP-impregnated toothbrushes can cause consumer as well as environmental exposure to Ag NPs.

  2. Combined biocidal action of silver nanoparticles and ions against Chlorococcales (Scenedesmus quadricauda, Chlorella vulgaris) and filamentous algae (Klebsormidium sp.).

    Science.gov (United States)

    Zouzelka, Radek; Cihakova, Pavlina; Rihova Ambrozova, Jana; Rathousky, Jiri

    2016-05-01

    Despite the extensive research, the mechanism of the antimicrobial and biocidal performance of silver nanoparticles has not been unequivocally elucidated yet. Our study was aimed at the investigation of the ability of silver nanoparticles to suppress the growth of three types of algae colonizing the wetted surfaces or submerged objects and the mechanism of their action. Silver nanoparticles exhibited a substantial toxicity towards Chlorococcales Scenedesmus quadricauda, Chlorella vulgaris, and filamentous algae Klebsormidium sp., which correlated with their particle size. The particles had very good stability against agglomeration even in the presence of multivalent cations. The concentration of silver ions in equilibrium with nanoparticles markedly depended on the particle size, achieving about 6 % and as low as about 0.1 % or even less for the particles 5 nm in size and for larger ones (40-70 nm), respectively. Even very limited proportion of small particles together with larger ones could substantially increase concentration of Ag ions in solution. The highest toxicity was found for the 5-nm-sized particles, being the smallest ones in this study. Their toxicity was even higher than that of silver ions at the same silver concentration. When compared as a function of the Ag(+) concentration in equilibrium with 5-nm particles, the toxicity of ions was at least 17 times higher than that obtained by dissolving silver nitrite (if not taking into account the effect of nanoparticles themselves). The mechanism of the toxicity of silver nanoparticles was found complex with an important role played by the adsorption of silver nanoparticles and the ions released from the particles on the cell surface. This mechanism could be described as some sort of synergy between nanoparticles and ions. While our study clearly showed the presence of this synergy, its detailed explanation is experimentally highly demanding, requiring a close cooperation between materials scientists

  3. In Vivo Toxicity of Silver Nanoparticles and Silver Ions in Zebrafish (Danio rerio

    Directory of Open Access Journals (Sweden)

    Katrine Bilberg

    2012-01-01

    Full Text Available The influence of water chemistry on characterised polyvinyl pyrrolidone- (PVP- coated silver nanoparticles (81 nm was investigated. NaCl solution series of 100–800 mg L−1 lead to initial and temporal increase in nanoparticles size, but agglomeration was limited. pH variation (5–8 had only minor influence on the hydrodynamic particle size. Acute toxicity of nanosivler to zebrafish (Danio rerio was investigated in a 48-hour static renewal study and compared with the toxicity of silver ions (AgNO3. The nanosilver and silver ion 48-hour median lethal concentration (LC50 values were 84 μg L−1 and 25 μg L−1, respectively. To investigate exposure-related stress, the fish behaviour was observed visually after 0, 3, 6, 12, 24, 27, 30, and 48 hours of both nanosilver and ionic silver treatments. These observations revealed increased rate of operculum movement and surface respiration after nanosilver exposure, suggesting respiratory toxicity. The present study demonstrates that silver nanoparticles are lethal to zebrafish.

  4. DETERMINATION OF METAL IONS RELEASED BY STAINLESS ...

    African Journals Online (AJOL)

    The amounts of cobalt, iron, manganese, nickel and chromium ions released from new and reused stainless steel arch bar used for maxillomandibular fixation was determined in Hank's solutions of different hydrogen and chloride ions concentrations, whole blood serum and phosphate buffered saline (PBS) in vitro, over a ...

  5. USE OF SILVER IONS IN PASTEURIZED MILK PRODUCTION

    OpenAIRE

    A. Mamaev; K. Leshukov; S. Stepanova

    2012-01-01

    The means of pasteurized milk shelf life prolongation by electro-chemical diffusion of silver ions has been introduced. Three samples of pasteurized milk were test subjects. In the course of study the following data have been examined: organoleptic, physicochemical, microbiological parameters of check samples and pilot samples of raw and pasteurized milk. Its shelf life has been determined. It has been determined that the test results of raw and pasteurized milk samples processed by various c...

  6. Separation of silver ions and starch modified silver nanoparticles using high performance liquid chromatography with ultraviolet and inductively coupled mass spectrometric detection

    International Nuclear Information System (INIS)

    Hanley, Traci A.; Saadawi, Ryan; Zhang, Peng; Caruso, Joseph A.; Landero-Figueroa, Julio

    2014-01-01

    The production of commercially available products marketed to contain silver nanoparticles is rapidly increasing. Species-specific toxicity is a phenomenon associated with many elements, including silver, making it imperative to develop a method to identify and quantify the various forms of silver (namely, silver ions vs. silver nanoparticles) possibly present in these products. In this study a method was developed using high performance liquid chromatography (HPLC) with ultraviolet (UV–VIS) and inductively coupled mass spectrometric (ICP-MS) detection to separate starch stabilized silver nanoparticles (AgNPs) and silver ions (Ag + ) by cation exchange chromatography with 0.5 M nitric acid mobile phase. The silver nanoparticles and ions were baseline resolved with an ICP-MS response linear over four orders of magnitude, 0.04 mg kg −1 detection limit, and 90% chromatographic recovery for silver solutions containing ions and starch stabilized silver nanoparticles smaller than 100 nm

  7. Separation of silver ions and starch modified silver nanoparticles using high performance liquid chromatography with ultraviolet and inductively coupled mass spectrometric detection

    Energy Technology Data Exchange (ETDEWEB)

    Hanley, Traci A.; Saadawi, Ryan; Zhang, Peng; Caruso, Joseph A., E-mail: joseph.caruso@uc.edu; Landero-Figueroa, Julio

    2014-10-01

    The production of commercially available products marketed to contain silver nanoparticles is rapidly increasing. Species-specific toxicity is a phenomenon associated with many elements, including silver, making it imperative to develop a method to identify and quantify the various forms of silver (namely, silver ions vs. silver nanoparticles) possibly present in these products. In this study a method was developed using high performance liquid chromatography (HPLC) with ultraviolet (UV–VIS) and inductively coupled mass spectrometric (ICP-MS) detection to separate starch stabilized silver nanoparticles (AgNPs) and silver ions (Ag{sup +}) by cation exchange chromatography with 0.5 M nitric acid mobile phase. The silver nanoparticles and ions were baseline resolved with an ICP-MS response linear over four orders of magnitude, 0.04 mg kg{sup −1} detection limit, and 90% chromatographic recovery for silver solutions containing ions and starch stabilized silver nanoparticles smaller than 100 nm.

  8. Electrical studies on silver based fast ion conducting glassy materials

    International Nuclear Information System (INIS)

    Rao, B. Appa; Kumar, E. Ramesh; Kumari, K. Rajani; Bhikshamaiah, G.

    2014-01-01

    Among all the available fast ion conductors, silver based glasses exhibit high conductivity. Further, glasses containing silver iodide enhances fast ion conducting behavior at room temperature. Glasses of various compositions of silver based fast ion conductors in the AgI−Ag 2 O−[(1−x)B 2 O 3 −xTeO 2 ] (x=0 to1 mol% in steps of 0.2) glassy system have been prepared by melt quenching method. The glassy nature of the compounds has been confirmed by X-ray diffraction. The electrical conductivity (AC) measurements have been carried out in the frequency range of 1 KHz–3MHz by Impedance Analyzer in the temperature range 303–423K. The DC conductivity measurements were also carried out in the temperature range 300–523K. From both AC and DC conductivity studies, it is found that the conductivity increases and activation energy decreases with increasing the concentration of TeO 2 as well as with temperature. The conductivity of the present glass system is found to be of the order of 10 −2 S/cm at room temperature. The ionic transport number of these glasses is found to be 0.999 indicating that these glasses can be used as electrolyte in batteries

  9. Silver ion-mediated killing of a food pathogen: Melting curve analysis data of silver resistance genes and growth curve data

    OpenAIRE

    Kuppan Gokulan; Katherine Williams; Sangeeta Khare

    2017-01-01

    Limited antibacterial activity of silver ions leached from silver-impregnated food contact materials could be due to: 1) the presence of silver resistance genes in tested bacteria; or 2) lack of susceptibility to silver ion-mediated killing in the bacterial strain (K. Williams, L. Valencia, K. Gokulan, R. Trbojevich, S. Khare, 2016 [1]). This study contains data to address the specificity of silver resistance genes in Salmonella Typhimurium during the real time PCR using melting curve analysi...

  10. Tunable Release of Silver Nanoparticles from Temperature-Responsive Polymer Blends.

    Czech Academy of Sciences Publication Activity Database

    Elashnikov, R.; Lyutakov, O.; Kalachyova, Y.; Solovyev, Andrey; Švorčík, V.

    2015-01-01

    Roč. 93, AUG (2015), s. 163-169 ISSN 1381-5148 Institutional support: RVO:67985858 Keywords : stimuli-responsive * release * silver nanoparticles Subject RIV: CC - Organic Chemistry Impact factor: 2.725, year: 2015

  11. The characterization of the antibacterial efficacy of an electrically activated silver ion-based surface system

    Science.gov (United States)

    Shirwaiker, Rohan A.

    There have been growing concerns in the global healthcare system about the eradication of pathogens in hospitals and other health-critical environments. The problem has been aggravated by the overuse of antibiotics and antimicrobial agents leading to the emergence of antibiotic-resistant superbugs such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE) which are difficult to kill. Lower immunity of sick patients coupled with the escalating concurrent problem of antibiotic-resistant pathogens has resulted in increasing incidences of hospital acquired (nosocomial) infections. There is an immediate need to control the transmission of such infections, primarily in healthcare environments, by creating touch-contact and work surfaces (e.g., door knobs, push plates, countertops) that utilize alternative antibacterial materials like the heavy metal, silver. Recent research has shown that it is silver in its ionic (Ag+ ) and not elemental form that is antibacterial. Thus, silver-based antibacterial surfaces have to release silver ions directly into the pathogenic environment (generally, an aqueous media) in order to be effective. This dissertation presents the study and analysis of a new silver-based surface system that utilizes low intensity direct electric current (LIDC) for generation of silver ions to primarily inhibit indirect contact transmission of infections. The broader objective of this research is to understand the design, and characterization of the electrically activated silver ion-based antibacterial surface system. The specific objectives of this dissertation include: (1) Developing a comprehensive system design, and identifying and studying its critical design parameters and functional mechanisms. (2) Evaluating effects of the critical design parameters on the antibacterial efficacy of the proposed surface system. (3) Developing a response surface model for the surface system performance. These objectives are

  12. Silver ion-mediated killing of a food pathogen: Melting curve analysis data of silver resistance genes and growth curve data

    Directory of Open Access Journals (Sweden)

    Kuppan Gokulan

    2017-04-01

    Full Text Available Limited antibacterial activity of silver ions leached from silver-impregnated food contact materials could be due to: 1 the presence of silver resistance genes in tested bacteria; or 2 lack of susceptibility to silver ion-mediated killing in the bacterial strain (K. Williams, L. Valencia, K. Gokulan, R. Trbojevich, S. Khare, 2016 [1]. This study contains data to address the specificity of silver resistance genes in Salmonella Typhimurium during the real time PCR using melting curve analysis and an assessment of the minimum inhibitory concentration of silver ions for Salmonella.

  13. Silver ion-mediated killing of a food pathogen: Melting curve analysis data of silver resistance genes and growth curve data.

    Science.gov (United States)

    Gokulan, Kuppan; Williams, Katherine; Khare, Sangeeta

    2017-04-01

    Limited antibacterial activity of silver ions leached from silver-impregnated food contact materials could be due to: 1) the presence of silver resistance genes in tested bacteria ; or 2) lack of susceptibility to silver ion-mediated killing in the bacterial strain (K. Williams, L. Valencia, K. Gokulan, R. Trbojevich, S. Khare, 2016 [1]). This study contains data to address the specificity of silver resistance genes in Salmonella Typhimurium during the real time PCR using melting curve analysis and an assessment of the minimum inhibitory concentration of silver ions for Salmonella .

  14. Antibacterial effects of electrospun chitosan/poly(ethylene oxide) nanofibrous membranes loaded with chlorhexidine and silver

    NARCIS (Netherlands)

    Song, J.; Remmers, S.J.; Shao, J.; Kolwijck, E.; Walboomers, X.F.; Jansen, J.A.; Leeuwenburgh, S.C.; Yang, F.

    2016-01-01

    To prevent percutaneous device associated infections (PDAIs), we prepared electrospun chitosan/poly(ethylene oxide) (PEO) nanofibrous membrane containing silver nanoparticles as an implantable delivery vehicle for the dual release of chlorhexidine and silver ions. We observed that the silver

  15. Ultrashort peptide nanogels release in situ generated silver manoparticles to combat emerging antimicrobial resistance strains

    KAUST Repository

    Seferji, Kholoud; Susapto, Hepi Hari; Arab, Wafaa Talat Abdullah; Sharip, Ainur; Sundaramurthi, Dhakshinamoorthy; Rauf, Sakandar; Hauser, Charlotte

    2017-01-01

    Nanogels made from self-assembling ultrashort peptides (3-6 amino acids in size) are promising biomaterials for various biomedical applications such as tissue engineering, drug delivery, regenerative medicine, microbiology and biosensing.We have developed silver-releasing peptide nanogels with promising wound care applications. The peptide nanogels allow a precise control of in situ syntesized silver nanoparticles (AgNPs), using soley short UV radiation and no other chemical reducing agent. We propose these silver-releasing nanogels as excellent biomaterial to combat emerging antimicrobial resistant strains.

  16. Ultrashort peptide nanogels release in situ generated silver manoparticles to combat emerging antimicrobial resistance strains

    KAUST Repository

    Seferji, Kholoud

    2017-01-08

    Nanogels made from self-assembling ultrashort peptides (3-6 amino acids in size) are promising biomaterials for various biomedical applications such as tissue engineering, drug delivery, regenerative medicine, microbiology and biosensing.We have developed silver-releasing peptide nanogels with promising wound care applications. The peptide nanogels allow a precise control of in situ syntesized silver nanoparticles (AgNPs), using soley short UV radiation and no other chemical reducing agent. We propose these silver-releasing nanogels as excellent biomaterial to combat emerging antimicrobial resistant strains.

  17. Ion Production by Laser Impact on a Silver Surface

    DEFF Research Database (Denmark)

    Christensen, Bo Toftmann; Schou, Jørgen

    Even at moderate fluence (0.6 -2.4 J/cm2) laser impact on metals in the UV regime results in a significant number of ions emitted from the surface. Even at this low fluence the particles ejected from a surface interact with each other in a so-called laser ablation plume. The ablated particles...... are largely neutrals at low fluence, but the fraction of ions increases strongly with fluence. We have irradiated silver in a vacuum chamber (~ 10-7 mbar) with a Nd:YAG laser at a wavelength of 355 nm. The ion flow in different directions has been measured with a hemispherical array of Langmuir probes...... range considered is also a typical range for pulsed laser deposition (PLD), by which the material is collected on a suitable substrate for thin film growth. PLD has the advantage compared with other film deposition methods, that even a complicated stoichiometry, e.g. metal oxides or alloys, can...

  18. Evaluation of bactericidal efficacy of silver ions on Escherichia coli for drinking water disinfection.

    Science.gov (United States)

    Pathak, Satya P; Gopal, K

    2012-07-01

    The purpose of this study is the development of a suitable process for the disinfection of drinking water by evaluating bactericidal efficacy of silver ions from silver electrodes. A prototype of a silver ioniser with silver electrodes and control unit has been fabricated. Silver ions from silver electrodes in water samples were estimated with an atomic absorption spectrophotometer. A fresh culture of Escherichia coli (1.75 × 10(3) c.f.u./ml) was exposed to 1, 2, 5, 10 and 20 ppb of silver ions in 100 ml of autoclaved tap water for 60 min. The effect of different pH and temperatures on bactericidal efficacy was observed at constant silver ion concentration (5 ppb) and contact time of 30 min. The maximum bactericidal activity (100%) was observed at 20 ppb of silver ion concentration indicating total disinfection after 20 min while minimum bactericidal activity (25%) was observed after 10 min at 01 ppb of silver ions. Likewise, 100% bactericidal activity was noticed with 2, 5 and 10 ppb of silver ions after 60, 50 and 40 min, respectively. Bactericidal activity at pH 5, 6, 7, 8 and 9 was observed at 79.9%, 79.8%, 80.5%, 100% and 100%, respectively, whereas it was 80.4%, 88.3%, 100%, 100% and 100% at 10°C, 20°C, 30°C, 40°C and 50°C, respectively. The findings of this study revealed that very low concentrations of silver ions at pH 8-9 and temperature >20°C have bactericidal efficacy for total disinfection of drinking water. Silver ionisation is suitable for water disinfection and an appropriate alternative to chlorination which forms carcinogenic disinfection by-products.

  19. Combined biocidal action of silver nanoparticles and ions against Chlorococcales (Scenedesmus quadricauda, Chlorella vulgaris) and filamentous algae (Klebsormidium sp.).

    Czech Academy of Sciences Publication Activity Database

    Žouželka, Radek; Čiháková, P.; Říhová Ambrožová, J.; Rathouský, Jiří

    2016-01-01

    Roč. 23, č. 19 (2016), s. 8317-8326 ISSN 0944-1344 R&D Projects: GA MK(CZ) DF11P01OVV012 Keywords : silver nanoparticles * silver ions * concentration of silver ions in equilibrium with silver nanoparticles Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.741, year: 2016

  20. Proteomic Analysis to Elucidate the Antibacterial Action of Silver Ions Against Bovine Mastitis Pathogens.

    Science.gov (United States)

    Kang, Seog Jin; Cho, Yong Il; Kim, Ki Hyun; Cho, Eun Seok

    2016-05-01

    Silver ions act as a powerful, broad-spectrum antimicrobial agent and are known to kill over 650 different kinds of pathogens. We investigated the protein expression pattern and identity after silver ion treatment in Escherichia coli and Staphylococcus aureus, which are primarily responsible for the majority of bovine mastitis cases using proteomics. Two-dimensional electrophoresis showed that silver ion treatment significantly reduced 5 spot's density in E. coli and S. aureus, respectively. We identified 10 proteins (alkyl hydroperoxide reductase C22 subunit, phosphoglucomutase, fructose-1-phosphate kinase, putative carbamoyl transferase, alpha-galactosidase, carbamate kinase, ornithine transcarbamoylase, fumarate hydratase class II, alcohol dehydrogenase, and conserved hypothetical protein) by matrix-assisted laser desorption ionization time of flight (MALDI-TOF). These results demonstrated that silver ions have bactericidal effects through energy deprivation, inhibition of DNA replication, and accumulation of oxidants in bovine mastitis pathogens and suggested that silver ions can be applied for the treatment of bovine mastitis.

  1. Comparison of silver release predictions using PARFUME with results from the AGR-2 irradiation experiment

    Energy Technology Data Exchange (ETDEWEB)

    Collin, Blaise P.; Demkowicz, Paul A.; Baldwin, Charles A.; Harp, Jason M.; Hunn, John D.

    2016-11-01

    The PARFUME (PARticle FUel ModEl) code was used to predict silver release from tristructural isotropic (TRISO) coated fuel particles and compacts during the second irradiation experiment (AGR-2) of the Advanced Gas Reactor Fuel Development and Qualification program. The PARFUME model for the AGR-2 experiment used the fuel compact volume average temperature for each of the 559 days of irradiation to calculate the release of fission product silver from a representative particle for a select number of AGR-2 compacts and individual fuel particles containing either mixed uranium carbide/oxide (UCO) or 100% uranium dioxide (UO2) kernels. Post-irradiation examination (PIE) measurements were performed to provide data on release of silver from these compacts and individual fuel particles. The available experimental fractional releases of silver were compared to their corresponding PARFUME predictions. Preliminary comparisons show that PARFUME under-predicts the PIE results in UCO compacts and is in reasonable agreement with experimental data for UO2 compacts. The accuracy of PARFUME predictions is impacted by the code limitations in the modeling of the temporal and spatial distributions of the temperature across the compacts. Nevertheless, the comparisons on silver release lie within the same order of magnitude.

  2. The effects of silver ions on copper metabolism in rats.

    Science.gov (United States)

    Ilyechova, E Yu; Saveliev, A N; Skvortsov, A N; Babich, P S; Zatulovskaia, Yu A; Pliss, M G; Korzhevskii, D E; Tsymbalenko, N V; Puchkova, L V

    2014-10-01

    The influence of short and prolonged diet containing silver ions (Ag-diet) on copper metabolism was studied. Two groups of animals were used: one group of adult rats received a Ag-diet for one month (Ag-A1) and another group received a Ag-diet for 6 months from birth (Ag-N6). In Ag-A1 rats, the Ag-diet caused a dramatic decrease of copper status indexes that was manifested as ceruloplasmin-associated copper deficiency. In Ag-N6 rats, copper status indexes decreased only 2-fold as compared to control rats. In rats of both groups, silver entered the bloodstream and accumulated in the liver. Silver was incorporated into ceruloplasmin (Cp), but not SOD1. In the liver, a prolonged Ag-diet caused a decrease of the expression level of genes, associated with copper metabolism. Comparative spectrophotometric analysis of partially purified Cp fractions has shown that Cp from Ag-N6 rats was closer to holo-Cp by specific enzymatic activities and tertiary structure than Cp from Ag-A1 rats. However, Cp of Ag-N6 differs from control holo-Cp and Cp of Ag-A1 in its affinity to DEAE-Sepharose and in its binding properties to lectins. In the bloodstream of Ag-N6, two Cp forms are present as shown in pulse-experiments on rats with the liver isolated from circulation. One of the Cp isoforms is of hepatic origin, and the other is of extrahepatic origin; the latter is characterized by a faster rate of secretion than hepatic Cp. These data allowed us to suggest that the disturbance of holo-Cp formation in the liver was compensated by induction of extrahepatic Cp synthesis. The possible biological importance of these effects is discussed.

  3. Kinetics of silver release from microfuel with taking into account the limited-solubility effect

    Science.gov (United States)

    Ivanov, A. S.; Rusinkevich, A. A.

    2014-12-01

    The effect of a limited solubility of silver in silicon carbide on silver release from a microfuel with a TRISO coating is studied. It is shown that a limited solubility affects substantially both concentration profiles and silver release from a microfuel over a broad range of temperatures. A procedure is developed for obtaining fission-product concentration profiles in a microfuel and graphs representing the flow and integrated release of fission products on the basis of data from neutron-physics calculations and results obtained by calculating thermodynamics with the aid of the Ivtanthermo code and kinetics with the aid of the FP-Kinetics code. This procedure takes into account a limited solubility of fission products in protective coatings of microfuel.

  4. Cytotoxicity and ion release of alloy nanoparticles

    International Nuclear Information System (INIS)

    Hahn, Anne; Fuhlrott, Jutta; Loos, Anneke; Barcikowski, Stephan

    2012-01-01

    It is well-known that nanoparticles could cause toxic effects in cells. Alloy nanoparticles with yet unknown health risk may be released from cardiovascular implants made of Nickel–Titanium or Cobalt–Chromium due to abrasion or production failure. We show the bio-response of human primary endothelial and smooth muscle cells exposed to different concentrations of metal and alloy nanoparticles. Nanoparticles having primary particle sizes in the range of 5–250 nm were generated using laser ablation in three different solutions avoiding artificial chemical additives, and giving access to formulations containing nanoparticles only stabilized by biological ligands. Endothelial cells are found to be more sensitive to nanoparticle exposure than smooth muscle cells. Cobalt and Nickel nanoparticles caused the highest cytotoxicity. In contrast, Titanium, Nickel–Iron, and Nickel–Titanium nanoparticles had almost no influence on cells below a nanoparticle concentration of 10 μM. Nanoparticles in cysteine dissolved almost completely, whereas less ions are released when nanoparticles were stabilized in water or citrate solution. Nanoparticles stabilized by cysteine caused less inhibitory effects on cells suggesting cysteine to form metal complexes with bioactive ions in media.

  5. Plasma immersion ion implantation for reducing metal ion release

    Energy Technology Data Exchange (ETDEWEB)

    Diaz, C.; Garcia, J. A.; Maendl, S.; Pereiro, R.; Fernandez, B.; Rodriguez, R. J. [Centro de Ingenieria Avanzada de Superficies AIN, 31191, Cordovilla-Pamplona (Spain); Leibniz-Institut fuer Oberflaechenmodifizierung, 04318 Leipzig (Germany); Universidad de Oviedo, Departamento Quimica Fisica y Analitica (Spain); Centro de Ingenieria Avanzada de Superficies AIN, 31191, Cordovilla-Pamplona (Spain)

    2012-11-06

    Plasma immersion ion implantation of Nitrogen and Oxygen on CoCrMo alloys was carried out to improve the tribological and corrosion behaviors of these biomedical alloys. In order to optimize the implantation results we were carried experiments at different temperatures. Tribocorrosion tests in bovine serum were used to measure Co, Cr and Mo releasing by using Inductively Coupled Plasma Mass Spectrometry analysis after tests. Also, X-ray Diffraction analysis were employed in order to explain any obtained difference in wear rate and corrosion tests. Wear tests reveals important decreases in rate of more than one order of magnitude for the best treatment. Moreover decreases in metal release were found for all the implanted samples, preserving the same corrosion resistance of the unimplanted samples. Finally this paper gathers an analysis, in terms of implantation parameters and achieved properties for industrial implementation of these treatments.

  6. [Fluorescence Resonance Energy Transfer Detection of Cobalt Ions by Silver Triangular Nanoplates and Rhodamine 6G].

    Science.gov (United States)

    Zhang, Xiu-qing; Peng, Jun; Ling, Jian; Liu, Chao-juan; Cao, Qiu-e; Ding, Zhong-tao

    2015-04-01

    In the present paper, the authors studied fluorescence resonance energy transfer (FRET) phenomenon between silver triangular nanoplates and bovine serum albumin (BSA)/Rhodamine 6G fluorescence complex, and established a fluorescence method for the detection of cobalt ions. We found that when increasing the silver triangular nanoplates added to certain concentrations of fluorescent bovine serum albumin (BSA)/Rhodamine 6G complex, the fluorescence of Rhodamine 6G would be quenched up to 80% due to the FRET between the quencher and donor. However, in the presence of cobalt ions, the disassociation of the fluorescent complex from silver triangular nanoplates occurred and the fluorescence of the Rhodamine 6G recovered. The recovery of fluorescence intensity rate (I/I0) has a good relationship with the cobalt ion concentration (cCO2+) added. Thus, the authors developed a fluorescence method for the detection of cobalt ions based on the FRET of silver triangular nanoplates and Rhodamine 6G.

  7. Compact Chemical Monitor for Silver Ions in Spacecraft Water Systems, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA has identified silver ions as the best candidate biocide for use in the potable water system on next-generation spacecraft. Though significant work has been...

  8. Advances in silver ion chromatography for the analysis of fatty acids and triacylglycerols-2001 to 2011.

    Science.gov (United States)

    Momchilova, Svetlana M; Nikolova-Damyanova, Boryana M

    2012-01-01

    An effort is made to critically present the achievements in silver ion chromatography during the last decade. Novelties in columns, mobile-phase compositions and detectors are described. Recent applications of silver ion chromatography in the analysis of fatty acids and triacylglycerols are presented while stressing novel analytical strategies or new objects. The tendencies in the application of the method in complementary ways with reversed-phase chromatography, chiral chromatography and, especially, mass detection are outlined.

  9. Inactivation of the antibacterial and cytotoxic properties of silver ions by biologically relevant compounds.

    Directory of Open Access Journals (Sweden)

    Geraldine Mulley

    Full Text Available There has been a recent surge in the use of silver as an antimicrobial agent in a wide range of domestic and clinical products, intended to prevent or treat bacterial infections and reduce bacterial colonization of surfaces. It has been reported that the antibacterial and cytotoxic properties of silver are affected by the assay conditions, particularly the type of growth media used in vitro. The toxicity of Ag+ to bacterial cells is comparable to that of human cells. We demonstrate that biologically relevant compounds such as glutathione, cysteine and human blood components significantly reduce the toxicity of silver ions to clinically relevant pathogenic bacteria and primary human dermal fibroblasts (skin cells. Bacteria are able to grow normally in the presence of silver nitrate at >20-fold the minimum inhibitory concentration (MIC if Ag+ and thiols are added in a 1:1 ratio because the reaction of Ag+ with extracellular thiols prevents silver ions from interacting with cells. Extracellular thiols and human serum also significantly reduce the antimicrobial activity of silver wound dressings Aquacel-Ag (Convatec and Acticoat (Smith & Nephew to Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli in vitro. These results have important implications for the deployment of silver as an antimicrobial agent in environments exposed to biological tissue or secretions. Significant amounts of money and effort have been directed at the development of silver-coated medical devices (e.g. dressings, catheters, implants. We believe our findings are essential for the effective design and testing of antimicrobial silver coatings.

  10. Silver nanoparticle release from commercially available plastic food containers into food simulants

    International Nuclear Information System (INIS)

    Mackevica, Aiga; Olsson, Mikael Emil; Hansen, Steffen Foss

    2016-01-01

    Silver nanoparticles (AgNPs) are currently being used in many different kinds of consumer products in order to take advantage of their antimicrobial properties. However, the potential migration of silver nanoparticles into food and subsequent consumer exposure has hardly been addressed. In the current study, we investigated four brands of commercially available plastic food storage containers and measured the total amount of silver, particle size and number concentration, and the migration rates into three different food simulants (Milli-Q grade water, 10 % ethanol, and 3 % acetic acid) for 10 days at 40 °C. The experimental setup was made according to the European Commission Directive (EU 10/2011) for articles intended to be in contact with food. The total amount of silver in plastic containers and migration solutions was quantified by ICP-MS analysis, and the size of the migrated particles was investigated by single particle ICP-MS and TEM-EDS. The total mass and median size of released particulate Ag were generally highest in 3 % acetic acid for three out of four food container brands. The total content of silver in the containers varied from 13 to 42 µg/g. The highest migration was observed in the 3 % acetic acid food simulant for all four brands of containers, with total silver release up to 3.1 ng/cm 2 after 10 days. In conclusion, the experimental results show that silver has the potential of migrating into food, especially when in contact with more acidic substances

  11. Silver nanoparticle release from commercially available plastic food containers into food simulants

    Energy Technology Data Exchange (ETDEWEB)

    Mackevica, Aiga, E-mail: aima@env.dtu.dk; Olsson, Mikael Emil; Hansen, Steffen Foss [Technical University of Denmark, Department of Environmental Engineering (Denmark)

    2016-01-15

    Silver nanoparticles (AgNPs) are currently being used in many different kinds of consumer products in order to take advantage of their antimicrobial properties. However, the potential migration of silver nanoparticles into food and subsequent consumer exposure has hardly been addressed. In the current study, we investigated four brands of commercially available plastic food storage containers and measured the total amount of silver, particle size and number concentration, and the migration rates into three different food simulants (Milli-Q grade water, 10 % ethanol, and 3 % acetic acid) for 10 days at 40 °C. The experimental setup was made according to the European Commission Directive (EU 10/2011) for articles intended to be in contact with food. The total amount of silver in plastic containers and migration solutions was quantified by ICP-MS analysis, and the size of the migrated particles was investigated by single particle ICP-MS and TEM-EDS. The total mass and median size of released particulate Ag were generally highest in 3 % acetic acid for three out of four food container brands. The total content of silver in the containers varied from 13 to 42 µg/g. The highest migration was observed in the 3 % acetic acid food simulant for all four brands of containers, with total silver release up to 3.1 ng/cm{sup 2} after 10 days. In conclusion, the experimental results show that silver has the potential of migrating into food, especially when in contact with more acidic substances.

  12. A Study of Antibioactivity of Nanosilver Colloid and Silver Ion Solution

    Directory of Open Access Journals (Sweden)

    Kuo-Hsiung Tseng

    2014-01-01

    Full Text Available The colloidal silver solution was successfully prepared in dielectric fluid by using electrical spark discharge (ESD without any surfactants. It does not require the toxic chemical agents in the process, which may affect the effectiveness of nanosilver colloid as an antibacterial agent. Nanocolloidal silver produced by ESD is characterized as low cost, zero environmental pollution, continuous, and rapid mass production process. In order to test the effect of antibioactivity, nanosilver dough was tested; the silver nanofluid was prepared by ESD machine, made into dough at different concentrations, and fermented for three hours in order to observe changes in the diameter of the dough. The results showed that the effect of effectiveness of nanosilver at the concentration of 100 ppm was weak, whereas the effect of 60 ppm silver ion (100 ppm AgNO3 was significant, as the dissociation rate of silver ion concentration correlates to the antibioactivity.

  13. In situ green synthesis of antimicrobial carboxymethyl chitosan-nanosilver hybrids with controlled silver release.

    Science.gov (United States)

    Huang, Siqi; Yu, Zhiming; Zhang, Yang; Qi, Chusheng; Zhang, Shifeng

    2017-01-01

    In order to fabricate antimicrobial carboxymethyl chitosan-nanosilver (CMC-Ag) hybrids with controlled silver release, this study demonstrated comparable formation via three synthetic protocols: 1) carboxymethyl chitosan (CMC) and glucose (adding glucose after AgNO 3 ), 2) CMC and glucose (adding glucose before AgNO 3 ), and 3) CMC only. Under principles of green chemistry, the synthesis was conducted in an aqueous medium exposed to microwave irradiation for 10 minutes with nontoxic chemicals. The structure and formation mechanisms of the three CMC-Ag hybrids were explored using X-ray diffraction, ultraviolet-visible spectroscopy, transmission electron microscopy, and Fourier-transform infrared analyses. Additionally, antimicrobial activity and in vitro silver release of the three synthesized hybrids were investigated in detail. The results revealed that a large number of stable, uniform, and small silver nanoparticles (AgNPs) were synthesized in situ on CMC chains via protocol 1. AgNPs were well dispersed with narrow size distribution in the range of 6-20 nm, with mean diameter only 12.22±2.57 nm. The addition of glucose resulted in greater AgNP synthesis. The order of addition of glucose and AgNO 3 significantly affected particle size and size distribution of AgNPs. Compared to CMC alone and commercially available AgNPs, the antimicrobial activities of three hybrids were significantly improved. Of the three hybrids, CMC-Ag1 synthesized via protocol 1 exhibited better antimicrobial activity than CMC-Ag2 and CMC-Ag3, and showed more effective inhibition of Staphylococcus aureus than Escherichia coli . Due to strong coordination and electrostatic interactions between CMC and silver and good steric protection provided by CMC, CMC-Ag1 displayed stable and continuous silver release and better performance in retaining silver for prolonged periods than CMC-Ag2 and CMC-Ag3.

  14. In situ green synthesis of antimicrobial carboxymethyl chitosan–nanosilver hybrids with controlled silver release

    Science.gov (United States)

    Huang, Siqi; Yu, Zhiming; Zhang, Yang; Qi, Chusheng; Zhang, Shifeng

    2017-01-01

    In order to fabricate antimicrobial carboxymethyl chitosan–nanosilver (CMC-Ag) hybrids with controlled silver release, this study demonstrated comparable formation via three synthetic protocols: 1) carboxymethyl chitosan (CMC) and glucose (adding glucose after AgNO3), 2) CMC and glucose (adding glucose before AgNO3), and 3) CMC only. Under principles of green chemistry, the synthesis was conducted in an aqueous medium exposed to microwave irradiation for 10 minutes with nontoxic chemicals. The structure and formation mechanisms of the three CMC-Ag hybrids were explored using X-ray diffraction, ultraviolet-visible spectroscopy, transmission electron microscopy, and Fourier-transform infrared analyses. Additionally, antimicrobial activity and in vitro silver release of the three synthesized hybrids were investigated in detail. The results revealed that a large number of stable, uniform, and small silver nanoparticles (AgNPs) were synthesized in situ on CMC chains via protocol 1. AgNPs were well dispersed with narrow size distribution in the range of 6–20 nm, with mean diameter only 12.22±2.57 nm. The addition of glucose resulted in greater AgNP synthesis. The order of addition of glucose and AgNO3 significantly affected particle size and size distribution of AgNPs. Compared to CMC alone and commercially available AgNPs, the antimicrobial activities of three hybrids were significantly improved. Of the three hybrids, CMC-Ag1 synthesized via protocol 1 exhibited better antimicrobial activity than CMC-Ag2 and CMC-Ag3, and showed more effective inhibition of Staphylococcus aureus than Escherichia coli. Due to strong coordination and electrostatic interactions between CMC and silver and good steric protection provided by CMC, CMC-Ag1 displayed stable and continuous silver release and better performance in retaining silver for prolonged periods than CMC-Ag2 and CMC-Ag3. PMID:28458539

  15. Silver speciation and characterization of nanoparticles released from plastic food containers by single particle ICPMS.

    Science.gov (United States)

    Ramos, K; Gómez-Gómez, M M; Cámara, C; Ramos, L

    2016-05-01

    Silver migration from a commercial baby feeding bottle and a food box containing AgNPs, as confirmed by SEM-EDX analysis, was evaluated using food simulant solutions [i.e., water, 3% (v/v) acetic acid, and 10% and 90% (v/v) ethanol]. Silver release was investigated at temperatures in the 20-70°C range using contact times of up to 10 days. Migration of silver from the food box was in all cases 2 to 3 orders of magnitude higher than that observed for the baby bottle, although the total silver content in the original box material was half of that found in the baby bottle. As expected, for both food containers, silver migration depended on both the nature of the tested solution and the applied conditions. The highest release was observed for 3% acetic acid at 70°C for 2h, corresponding to 62ngdm(2) and 1887ngdm(-2) of silver for the baby bottle and the food box, respectively. Single particle-inductively coupled plasma mass spectrometry (SP-ICPMS) was used to characterise and quantify AgNPs in the food simulants extracts. Sample preparation was optimized to preserve AgNPs integrity. The experimental parameters affecting AgNPs detection, sizing and quantification by SP-ICPMS were also optimised. Analyses of water and acidic extracts revealed the presence of both dissolved silver and AgNPs. Small AgNPs (in the 18-30nm range) and particle number concentrations within the 4-1510 10(6)L(-1) range were detected, corresponding to only 0.1-8.6% of the total silver released from these materials. The only exception was AgNPs migrated into water at 40°C and 70°C from the food box, which accounted for as much as 34% and 69% of the total silver content, respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Synergistic effects of iodine and silver ions co-implanted in 6H–SiC

    International Nuclear Information System (INIS)

    Kuhudzai, R.J.; Malherbe, J.B.; Hlatshwayo, T.T.; Berg, N.G. van der; Devaraj, A.; Zhu, Z.; Nandasiri, M.

    2015-01-01

    Motivated by the aim of understanding the release of fission products through the SiC coating of fuel kernels in modern high temperature nuclear reactors, a fundamental investigation is conducted to understand the synergistic effects of implanted silver (Ag) and iodine (I) in 6H–SiC. The implantation of the individual species, as well as the co-implantation of 360 keV ions of I and Ag at room temperature in 6H–SiC and their subsequent annealing behaviour has been investigated by Secondary Ion Mass Spectrometry (SIMS), Atom Probe Tomography (APT) and X-ray Photoelectron Spectroscopy (XPS). SIMS and APT measurements indicated the presence of Ag in the co-implanted samples after annealing at 1500 °C for 30 h in sharp contrast to the samples implanted with Ag only. In samples implanted with Ag only, complete loss of the implanted Ag was observed. However, for I only implanted samples, some iodine was retained. APT of annealed co-implanted 6H–SiC showed clear spatial association of Ag and I clusters in SiC, which can be attributed to the observed I assisted retention of Ag after annealing. Such detailed studies will be necessary to identify the fundamental mechanism of fission products migration through SiC coatings. - Highlights: • Co-implantation of Ag and I ions in 6H–SiC was performed. • Clear spatial association of Ag and I clusters observed after annealing. • Complete loss of Ag after high temperature annealing of silver only sample. • Iodine was retained in iodine only sample after high temperature annealing. • Iodine was found to play a role in the retention of Ag in the co-implanted samples.

  17. Three-dimensional printed knotted reactors enabling highly sensitive differentiation of silver nanoparticles and ions in aqueous environmental samples

    Energy Technology Data Exchange (ETDEWEB)

    Su, Cheng-Kuan, E-mail: chengkuan@ntou.edu.tw [Department of Bioscience and Biotechnology, National Taiwan Ocean University, Keelung, 20224, Taiwan, ROC (China); Hsieh, Meng-Hsuan [Department of Biomedical Engineering and Environmental Sciences, National Tsing-Hua University, Hsinchu, 30013, Taiwan, ROC (China); Sun, Yuh-Chang, E-mail: ycsun@mx.nthu.edu.tw [Department of Biomedical Engineering and Environmental Sciences, National Tsing-Hua University, Hsinchu, 30013, Taiwan, ROC (China)

    2016-03-31

    Whether silver nanoparticles (AgNPs) persist or release silver ions (Ag{sup +}) when discharged into a natural environment has remained an unresolved issue. In this study, we employed a low-cost stereolithographic three-dimensional printing (3DP) technology to fabricate the angle-defined knotted reactors (KRs) to construct a simple differentiation scheme for quantitative assessment of Ag{sup +} ions and AgNPs in municipal wastewater samples. We chose xanthan/phosphate-buffered saline as a dispersion medium for in situ stabilization of the two silver species, while also facilitating their extraction from complicated wastewater matrices. After method optimization, we measured extraction efficiencies of 54.5 and 32.3% for retaining Ag{sup +} ions and AgNPs, respectively, in the printed KR (768-turn), with detection limits (DLs) of 0.86 and 0.52 ng L{sup −1} when determining Ag{sup +} ions and AgNPs, respectively (sample run at pH 11 without a rinse solution), and 0.86 ng L{sup −1} when determining Ag{sup +} ions alone (sample run at pH 12 with a 1.5-mL rinse solution). The proposed scheme is tolerant of the wastewater matrix and provides more reliable differentiation between Ag{sup +}/AgNPs than does a conventional filtration method. The concept and applicability of adopting 3DP technology to renew traditional KR devices were evidently proven by means of these significantly improved analytical performance. Our analytical data suggested that the concentrations of Ag{sup +} ions and AgNPs in the tested industrial wastewater sample were both higher than those in domestic wastewater, implying that industrial activity might be a main source of environmental silver species, rather than domestic discharge from AgNP-containing products. - Highlights: • 3D printed knotted reactors are utilized to differentiate AgNPs and Ag{sup +} ions. • Xanthan/phosphate-buffered saline is used for stabilizing the two silver species. • Extraction efficiency up to 54.5% is

  18. Three-dimensional printed knotted reactors enabling highly sensitive differentiation of silver nanoparticles and ions in aqueous environmental samples

    International Nuclear Information System (INIS)

    Su, Cheng-Kuan; Hsieh, Meng-Hsuan; Sun, Yuh-Chang

    2016-01-01

    Whether silver nanoparticles (AgNPs) persist or release silver ions (Ag + ) when discharged into a natural environment has remained an unresolved issue. In this study, we employed a low-cost stereolithographic three-dimensional printing (3DP) technology to fabricate the angle-defined knotted reactors (KRs) to construct a simple differentiation scheme for quantitative assessment of Ag + ions and AgNPs in municipal wastewater samples. We chose xanthan/phosphate-buffered saline as a dispersion medium for in situ stabilization of the two silver species, while also facilitating their extraction from complicated wastewater matrices. After method optimization, we measured extraction efficiencies of 54.5 and 32.3% for retaining Ag + ions and AgNPs, respectively, in the printed KR (768-turn), with detection limits (DLs) of 0.86 and 0.52 ng L −1 when determining Ag + ions and AgNPs, respectively (sample run at pH 11 without a rinse solution), and 0.86 ng L −1 when determining Ag + ions alone (sample run at pH 12 with a 1.5-mL rinse solution). The proposed scheme is tolerant of the wastewater matrix and provides more reliable differentiation between Ag + /AgNPs than does a conventional filtration method. The concept and applicability of adopting 3DP technology to renew traditional KR devices were evidently proven by means of these significantly improved analytical performance. Our analytical data suggested that the concentrations of Ag + ions and AgNPs in the tested industrial wastewater sample were both higher than those in domestic wastewater, implying that industrial activity might be a main source of environmental silver species, rather than domestic discharge from AgNP-containing products. - Highlights: • 3D printed knotted reactors are utilized to differentiate AgNPs and Ag + ions. • Xanthan/phosphate-buffered saline is used for stabilizing the two silver species. • Extraction efficiency up to 54.5% is available for retaining Ag + ion species. • The

  19. Chloride ion-dependent surface-enhanced Raman scattering study of biotin on the silver surface

    International Nuclear Information System (INIS)

    Liu Fangfang; Gu Huaimin; Yuan Xiaojuan; Dong Xiao; Lin Yue

    2011-01-01

    In the present paper, the surface enhanced Raman scattering (SERS) technique was employed to study the SERS spectra of biotin molecules formed on the silver surface. The adsorption geometries of biotin molecules on the silver surface were analyzed based on the SERS data. It can be found that most vibration modes show a Raman shift in silver sol after the addition of sodium chloride solution. In addition, The Raman signals of biotin become weaker and weaker with the increase of the concentration of sodium chloride. This may be due to that the interaction between chloride ions and silver particles is stronger than the interaction between biotin molecules and silver particles. When the concentration of sodium chloride in silver colloid is higher than 0.05mol/L, superfluous chloride ions may form an absorption layer so that biotin can not be adsorbed on silver surface directly. The changes in intensity and profile shape in the SERS spectra suggest different adsorption behavior and surface-coverage of biotin on silver surface. The SERS spectra of biotin suggest that the contribution of the charge transfer mechanism to SERS may be dominant.

  20. Protein-Modified-Paramagnetic-Particles as a Tool for Detection of Silver(I) Ions

    Science.gov (United States)

    Kizek, R.; Krizkova, S.; Adam, V.; Huska, D.; Hubalek, J.; Trnkova, L.

    2009-04-01

    In a number of published articles the toxic effect of silver(I) ions on aquatic organisms is described. Silver(I) ions in aquatic environment are stable in a wide range of pH. Under alkali pH AgOH and Ag(OH)2- can be formed. However, in water environment there are many compounds to interact with silver(I) ions. The most important ones are chloride anions, which forms insoluble precipitate with silver(I) ions (AgCl). The insoluble silver containing compounds do not pose any threat to aquatic organisms. Toxicity of silver ions is probably caused by their very good affinity to nucleic acids and also proteins. The binding into active enzyme site leads to the expressive enzyme reaction inhibition. Silver(I) ions are into living environment introduced thanks to anthropogenic activities. They easily contaminate atmosphere as well as aquatic environment or soils. Several authors described using of carbon electrode as working electrode for determination of silver. Recently, we have suggested heavy metal biosensor based on interaction of metal ions with low molecular mass protein called metallothionein (MT), which was adsorbed on the surface of hanging mercury drop electrode (HMDE). The biosensor was successfully used for detection of cadmium(II) and zinc(II) ions, cisplatin, cisplatin-DNA adducts and palladium(II) ions. Due to the convincing results with MT as biological component we report on suggesting of heavy metal biosensor based on immobilization of metallothionein (MT) on the surface of carbon paste electrode (CPE) via MT-antibodies. Primarily we studied of basic electrochemical behaviour of MT at surface of carbon paste electrode by using of square wave voltammetry (SWV). Detection limit (3 S/N) for MT was evaluated as 0.1 μg/ml. After that we have evaluated the electroactivity of MT at surface of SWV, we aimed our attention on the way of capturing of MT on the surface of CPE. We choose antibody against MT obtained from chicken eggs for these purposes. Antibodies

  1. Aqueous Dissolution of Silver Iodide and Associated Iodine Release Under Reducing Conditions with Sulfide

    International Nuclear Information System (INIS)

    Yaohiro Inagaki; Toshitaka Imamura; Kazuya Idemitsu; Tatsumi Arima; Osamu Kato; Hidekazu Asano; Tsutomu Nishimura

    2007-01-01

    Aqueous dissolution tests of silver iodide (AgI) were performed in Na 2 S solutions in order to evaluate, empirically, dissolution of AgI to release iodine under reducing conditions with sulfide. The results indicated that AgI dissolves to release iodine being controlled by mainly precipitation of Ag 2 S. However, the dissolution of AgI can be depressed to proceed, and the thermodynamic equilibrium cannot be attained easily. Solid phase analysis for the reacted AgI suggested that a thin layer of solid silver forming at AgI surface may evolve to be protective against transportation of reactant species, which can lead to the depression in the dissolution of AgI. (authors)

  2. Improved antimicrobial property and controlled drug release kinetics of silver sulfadiazine loaded ordered mesoporous silica

    Directory of Open Access Journals (Sweden)

    Suman Jangra

    2016-09-01

    Full Text Available The present study deals with the loading of silver sulfadiazine into ordered mesoporous silica material by post-impregnation method and its effect on the in vitro release kinetics and antimicrobial property of the drug. The formulated SBA-15 silica material with rope-like morphology and SBA-15-silver sulfadiazine (SBA-AgSD were characterized by UV–visible spectrophotometer, small and wide-angle powder X-ray diffraction (PXRD, field emission scanning electron microscope (FESEM and high resolution transmission electron microscope (HRTEM. Thermo-gravimetric analysis of SBA-AgSD revealed a high loading amount of 52.87%. Nitrogen adsorption–desorption analysis confirmed the drug entrapment into host material by revealing a reduced surface area (214 m2/g and pore diameter (6.7 nm of the SBA-AgSD. The controlled release of silver sulfadiazine drug from the mesoporous silica to simulated gastric, intestinal and body fluids was evaluated. The Korsmeyer–Peppas model fits the drug release data with the non-Fickian diffusion model and zero order kinetics of SBA-AgSD. The antibacterial performance of the SBA-AgSD was evaluated with respect to Staphylococcus aureus, Bacillus subtilis and Pseudomonas aeruginosa. The controlled drug delivery of the SBA-AgSD revealed improved antibacterial activity, thus endorsing its applicability in effective wound dressing.

  3. Synergistic effects of iodine and silver ions co-implanted in 6H-SiC

    Science.gov (United States)

    Kuhudzai, R. J.; Malherbe, J. B.; Hlatshwayo, T. T.; van der Berg, N. G.; Devaraj, A.; Zhu, Z.; Nandasiri, M.

    2015-12-01

    Motivated by the aim of understanding the release of fission products through the SiC coating of fuel kernels in modern high temperature nuclear reactors, a fundamental investigation is conducted to understand the synergistic effects of implanted silver (Ag) and iodine (I) in 6H-SiC. The implantation of the individual species, as well as the co-implantation of 360 keV ions of I and Ag at room temperature in 6H-SiC and their subsequent annealing behaviour has been investigated by Secondary Ion Mass Spectrometry (SIMS), Atom Probe Tomography (APT) and X-ray Photoelectron Spectroscopy (XPS). SIMS and APT measurements indicated the presence of Ag in the co-implanted samples after annealing at 1500 °C for 30 h in sharp contrast to the samples implanted with Ag only. In samples implanted with Ag only, complete loss of the implanted Ag was observed. However, for I only implanted samples, some iodine was retained. APT of annealed co-implanted 6H-SiC showed clear spatial association of Ag and I clusters in SiC, which can be attributed to the observed I assisted retention of Ag after annealing. Such detailed studies will be necessary to identify the fundamental mechanism of fission products migration through SiC coatings.

  4. TEM and SP-ICP-MS analysis of the release of silver nanoparticles from decoration of pastry.

    Science.gov (United States)

    Verleysen, E; Van Doren, E; Waegeneers, N; De Temmerman, P-J; Abi Daoud Francisco, M; Mast, J

    2015-04-08

    Metallic silver is an EU approved food additive referred to as E174. It is generally assumed that silver is only present in bulk form in the food chain. This work demonstrates that a simple treatment with water of "silver pearls", meant for decoration of pastry, results in the release of a subfraction of silver nanoparticles. The number-based size and shape distributions of the single, aggregated, and/or agglomerated particles released from the silver pearls were determined by combining conventional bright-field TEM imaging with semiautomatic particle detection and analysis. In addition, the crystal structure of the particles was studied by electron diffraction and chemical information was obtained by combining HAADF-STEM imaging with EDX spectroscopy and mapping. The TEM results were confirmed by SP-ICP-MS. The representative Ag test nanomaterial NM-300 K was used as a positive control to determine the uncertainty on the measurement of the size and shape of the particles.

  5. Highly selective and sensitive fluorescent chemosensor for femtomolar detection of silver ion in aqueous medium

    OpenAIRE

    Arulraj, Abraham Daniel; Devasenathipathy, Rajkumar; Chen, Shen-Ming; Vasantha, Vairathevar Sivasamy; Wang, Sea-Fue

    2015-01-01

    The chemical sensing for the trace level detection of silver ion in aqueous solution still remains a challenge using simple, rapid, and inexpensive method. We report that thionine can be used as a fluorescent probe for the detection of Ag+ ion. The successive addition of Ag+ ion to the solution containing thionine quenches (turns-off) the fluorescence intensity of thionine. Association and quenching constants have been estimated by the Benesi–Hildebrand method and Stern–Volmer plot, respectiv...

  6. Metallic ion release from biocompatible cobalt-based alloy

    Directory of Open Access Journals (Sweden)

    Dimić Ivana D.

    2014-01-01

    Full Text Available Metallic biomaterials, which are mainly used for the damaged hard tissue replacements, are materials with high strength, excellent toughness and good wear resistance. The disadvantages of metals as implant materials are their susceptibility to corrosion, the elastic modulus mismatch between metals and human hard tissues, relatively high density and metallic ion release which can cause serious health problems. The aim of this study was to examine metallic ion release from Co-Cr-Mo alloy in artificial saliva. In that purpose, alloy samples were immersed into artificial saliva with different pH values (4.0, 5.5 and 7.5. After a certain immersion period (1, 3 and 6 weeks the concentrations of released ions were determined using Inductively Coupled Plasma - Mass Spectrophotometer (ICP-MS. The research findings were used in order to define the dependence between the concentration of released metallic ions, artificial saliva pH values and immersion time. The determined released metallic ions concentrations were compared with literature data in order to describe and better understand the phenomenon of metallic ion release from the biocompatible cobalt-based alloy. [Projekat Ministarstva nauke Republike Srbije, br. III 46010 i br. ON 174004

  7. Impact of silver ions and silver nanoparticles on the plant growth and soil microorganisms

    Directory of Open Access Journals (Sweden)

    D. Tomacheski

    2017-12-01

    Full Text Available There is a growing consumer market for products that proclaim to decrease microorganism counts to prevent infections. Most of these products are loaded with silver in its ionic or nanoparticle form. Through use or during production, these particles can find their way into the soil and cause an impact in microbial and plant communities. This study aims to evaluate the impact of silver based particles in Avena byzantina (oat, Lactuca sativa (lettuce and Raphanus sativus (radish development and in the soil microorganism abundance. Oat, lettuce and radish plants were cultivated in soil contaminated with particles of bentonite organomodified with silver (Ag+_bentonite, silver phosphate glass (Ag+_phosphate and silver nanoparticles adsorbed on fumed silica (AgNp_silica. Plant development and microorganisms’ abundance were evaluated. To some degree, Ag+_bentonite impacted plants development and AgNp_silica causes an adverse effect on microbial abundance. The impact on plants and microorganisms was contradictory and varied according to soil and particles physicochemical characteristics.

  8. Leaching and antimicrobial properties of silver nanoparticles loaded onto natural zeolite clinoptilolite by ion exchange and wet impregnation

    CSIR Research Space (South Africa)

    Missengue, RNM

    2015-11-01

    Full Text Available This study aimed to compare the leaching and antimicrobial properties of silver that was loaded onto the natural zeolite clinoptilolite by ion exchange and wet impregnation. Silver ions were reduced using sodium borohydride (NaBH(sub4...

  9. Release Behavior and Antibacterial Activity of Chitosan/Alginate Blends with Aloe vera and Silver Nanoparticles.

    Science.gov (United States)

    Gómez Chabala, Luisa Fernanda; Cuartas, Claudia Elena Echeverri; López, Martha Elena Londoño

    2017-10-24

    Aloe vera is a perennial plant employed for medical, pharmaceutical and cosmetic purposes that is rich in amino acids, enzymes, vitamins and polysaccharides, which are responsible for its therapeutic properties. Incorporating these properties into a biopolymer film obtained from alginate and chitosan allowed the development of a novel wound dressing with antibacterial capacity and healing effects to integrate the antibacterial capacity of silver nanoparticles with the healing and emollient properties of Aloe vera gel. Three alginate-chitosan matrices were obtained through blending methods using different proportions of alginate, chitosan, the Aloe vera (AV) gel and silver nanoparticles (AgNps), which were incorporated into the polymeric system through immersion methods. Physical, chemical and antibacterial characteristics were evaluated in each matrix. Interaction between alginate and chitosan was identified using the Fourier transform infrared spectroscopy technique (FTIR), porosity was studied using scanning electron microscopy (SEM), swelling degree was calculated by difference in weight, Aloe vera gel release capacity was estimated by applying a drug model (Peppas) and finally antibacterial capacity was evaluated against S. Aureus and P. aeruginosa . Results show that alginate-chitosan (A (1:3 Chit 1/Alg 1); B (1:3 Chit 1.5/Alg 1) and C (3:1 Chit 1/Alg 1/B12)) matrices with Aloe vera (AV) gel and silver nanoparticles (AgNps) described here displayed antibacterial properties and absorption and Aloe vera release capacity making it a potential wound dressing for minor injuries.

  10. Ion time-of-flight study of laser ablation of silver in low pressure gases

    DEFF Research Database (Denmark)

    Hansen, T.N.; Schou, Jørgen; Lunney, J.G.

    1999-01-01

    The dynamics of ions from a laser-ablated silver target in low pressure background atmospheres have been investigated in a simple geometry using an electrical probe. A simple scattering picture for the first transmitted peak of the observed plume splitting has been used to calculate cross section...... of the ablated silver ions in oxygen (sigma{O(2)} = 4.8 x 10(-16) cm(2)) and in argon (sigma{Ar} = 6.7 x 10(-16) cm(2)). The dynamics of the blast wave is well described by blast wave theory. (C) 1999 Elsevier Science B.V. All rights reserved....

  11. Effects of chlorine and other water quality parameters on the release of silver nanoparticles from a ceramic surface.

    Science.gov (United States)

    Bielefeldt, Angela R; Stewart, Michael W; Mansfield, Elisabeth; Scott Summers, R; Ryan, Joseph N

    2013-08-01

    A quartz crystal microbalance was used to determine the effects of different water quality parameters on the detachment of silver nanoparticles from surfaces representative of ceramic pot filters (CPFs). Silver nanoparticles stabilized with casein were used in the experiments. The average hydrodynamic diameter of the nanoparticles ranged from 20 nm to 100 nm over a pH range of 6.5-10.5. The isoelectric point was about 3.5 and the zeta potential was -45 mV from pH 4.5 to 9.5. The silver nanoparticles were deposited onto silica surfaces and a quartz crystal microbalance was used to monitor silver release from the surface. At environmentally relevant ranges of pH (4.8-9.3), ionic strength (0 and 150 mol/m(3) NaNO3 or 150 mol/m(3) Ca(NO3)2), and turbidity (0 and 51.5 NTU kaolin clay), the rates of silver release were similar. A high concentration of sodium chloride and bacteria (Echerichia coli in 10% tryptic soy broth) caused rapid silver release. Water containing sodium hypochlorite removed 85% of the silver from the silica surface within 3 h. The results suggest that contact between CPFs and prechlorinated water or bleach CPF cleaning should be avoided. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. Nano-galvanic coupling for enhanced Ag+ release in ZrCN-Ag films : Antibacterial application

    NARCIS (Netherlands)

    Calderon, S.; Ferreri, I.; Henriques, M.; De Hosson, J. T. M.; Cavaleiro, A.; Carvalho, S.

    2016-01-01

    The antibacterial properties of materials developed for medical devices with embedded silver nanoparticles are enhanced by controlling the release of silver ions. In this study, a simple experimental procedure for the augmentation of the silver ion release from ZrCN-Ag coatings is described. The

  13. Silver ion recognition using potentiometric sensor based on recently synthesized isoquinoline-1,3-dione derivatives

    Directory of Open Access Journals (Sweden)

    AJAR KAMAL

    2012-08-01

    Full Text Available The four derivatives of isoquinoline-1,3-dione based on β-lactum (I-IV, have been explored as neutral ionophores for preparing poly(vinylchloride based polymeric membrane electrodes (PME selective to silver(I ions. The addition of sodium tetraphenylborate (NaTPB and dioctylsebacate (DOS as a plasticizer was found to improve the performance of ion selective electrodes. The best performance was obtained with PME-1 based on ionophore I having composition: ionophore (9.2 mg, PVC (100.1 mg, DOS (201.1 mg and NaTPB (1.5 mg in 5 mL tetrahydrofuran. The electrode response was linear with Nernstian slope of 58.44 mV/decade in the concentration range of 1.0 x 10-1 M to 5.0 x 10-6 M and detection limit of 5.83 x 10-6 M. It performs satisfactorily over wide pH range of 1.0-5.5. The proposed sensor can be used over a period of more than three months without any significant drift in potential and shows good selectivity to silver(I ion over a number of cations especially with no interference of mercury(II ions. Sharp end point was obtained when the sensor was used as an indicator electrode for the potentiometric titration of silver(I ions with chloride ions and therefore this electrode (PME-1 could be used for quantitative determination of silver(I ion in synthetic water, silver foil and dental amalgam samples.

  14. Analysis of metal ion release from biomedical implants

    Directory of Open Access Journals (Sweden)

    Ivana Dimić

    2013-06-01

    Full Text Available Metallic biomaterials are commonly used for fixation or replacement of damaged bones in the human body due to their good combination of mechanical properties. The disadvantage of metals as implant materials is their susceptibility to corrosion and metal ion release, which can cause serious health problems. In certain concentrations metals and metal ions are toxic and their presence can cause diverse inflammatory reactions, genetic mutations or even cancer. In this paper, different approaches to metal ion release examination, from biometallic materials sample preparation to research results interpretation, will be presented. An overview of the analytical techniques, used for determination of the type and concentration of released ions from implants in simulated biofluids, is also given in the paper.

  15. Polypyrrole-silver composites prepared by the reduction of silver ions with polypyrrole nanotubes

    Czech Academy of Sciences Publication Activity Database

    Škodová, J.; Kopecký, D.; Vrňata, M.; Varga, M.; Prokeš, J.; Cieslar, M.; Bober, Patrycja; Stejskal, Jaroslav

    2013-01-01

    Roč. 4, č. 12 (2013), s. 3610-3616 ISSN 1759-9954 R&D Projects: GA ČR(CZ) GA13-00270S Institutional support: RVO:61389013 Keywords : polypyrrole * silver * nanotubes Subject RIV: CD - Macromolecular Chemistry Impact factor: 5.368, year: 2013

  16. Effects of silver nanoparticles and ions on a co-culture model for the gastrointestinal epithelium.

    Science.gov (United States)

    Georgantzopoulou, Anastasia; Serchi, Tommaso; Cambier, Sébastien; Leclercq, Céline C; Renaut, Jenny; Shao, Jia; Kruszewski, Marcin; Lentzen, Esther; Grysan, Patrick; Eswara, Santhana; Audinot, Jean-Nicolas; Contal, Servane; Ziebel, Johanna; Guignard, Cédric; Hoffmann, Lucien; Murk, AlberTinka J; Gutleb, Arno C

    2016-02-17

    The increased incorporation of silver nanoparticles (Ag NPs) into consumer products makes the characterization of potential risk for humans and other organisms essential. The oral route is an important uptake route for NPs, therefore the study of the gastrointestinal tract in respect to NP uptake and toxicity is very timely. The aim of the present study was to evaluate the effects of Ag NPs and ions on a Caco-2/TC7:HT29-MTX intestinal co-culture model with mucus secretion, which constitutes an important protective barrier to exogenous agents in vivo and may strongly influence particle uptake. The presence of the mucus layer was confirmed with staining techniques (alcian blue and toluidine blue). Mono and co-cultures of Caco-2/TC7 and HT29-MTX cells were exposed to Ag NPs (Ag 20 and 200 nm) and AgNO3 and viability (alamar blue), ROS induction (DCFH-DA assay) and IL-8 release (ELISA) were measured. The particle agglomeration in the media was evaluated with DLS and the ion release with ultrafiltration and ICP-MS. The effects of the Ag NPs and AgNO3 on cells in co-culture were studied at a proteome level with two-dimensional difference in gel electrophoresis (2D-DIGE) followed by Matrix Assisted Laser Desorption Ionization - Time Of Flight/ Time Of Flight (MALDI-TOF/TOF) mass spectrometry (MS). Intracellular localization was assessed with NanoSIMS and TEM. The presence of mucus layer led to protection against ROS and decrease in IL-8 release. Both Ag 20 and 200 nm NPs were taken up by the cells and Ag NPs 20 nm were mainly localized in organelles with high sulfur content. A dose- and size-dependent increase in IL-8 release was observed with a lack of cytotoxicity and oxidative stress. Sixty one differentially abundant proteins were identified involved in cytoskeleton arrangement and cell cycle, oxidative stress, apoptosis, metabolism/detoxification and stress. The presence of mucus layer had an impact on modulating the induced toxicity of NPs. NP-specific effects were

  17. Interactive Relationship between Silver Ions and Silver Nanoparticles with PVA Prepared by the Submerged Arc Discharge Method

    Directory of Open Access Journals (Sweden)

    Kuo-Hsiung Tseng

    2018-01-01

    Full Text Available This study uses the submerged arc discharge method (SADM and the concentrated energy of arc to melt silver metal in deionized water (DW so as to prepare metal fluid with nanoparticles and submicron particles. The process is free from any chemical agent; it is rapid and simple, and rapid and mass production is available (0.5 L/min. Aside from the silver nanoparticle (Ag0, silver ions (Ag+ exist in the colloidal Ag prepared by the system. In the preparation of colloidal Ag, polyvinyl alcohol (PVA is used as an additive so that the Ag0/Ag+ concentration, arcing rate, peak, and scanning electron microscopic (SEM images in the cases with and without PVA can be analyzed. The findings show that the Ag0/Ag+ concentration increases with the addition level of PVA, while the nano-Ag and Ag+ electrode arcing rate rises. The UV-Vis absorption peak increases Ag0 absorbance and shifts as the dispersity increases with PVA addition. Lastly, with PVA addition, the proposed method can prepare smaller and more amounts of Ag0 nanoparticles, distributed uniformly. PVA possesses many distinct features such as cladding, dispersion, and stability.

  18. The influence of silver-ion doping using ion implantation on the luminescence properties of Er–Yb silicate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Stanek, S., E-mail: stanislav.stanek@vscht.cz [Department of Inorganic Chemistry, Faculty of Chemical Technology, University of Chemistry and Technology, Technicka 5, 16628 Prague (Czech Republic); Nekvindova, P.; Svecova, B.; Vytykacova, S.; Mika, M. [Department of Inorganic Chemistry, Faculty of Chemical Technology, University of Chemistry and Technology, Technicka 5, 16628 Prague (Czech Republic); Oswald, J. [Institute of Physics, Academy of Science of the Czech Republic, Cukrovarnicka 10/112, 162 00 Prague (Czech Republic); Mackova, A.; Malinsky, P. [Nuclear Physics Institute, Academy of Sciences of the Czech Republic, 25068 Rez (Czech Republic); Department of Physics, Faculty of Science, J.E. Purkinje University, Ceske mladeze 8, 40096 Usti nad Labem (Czech Republic); Spirkova, J. [Department of Inorganic Chemistry, Faculty of Chemical Technology, University of Chemistry and Technology, Technicka 5, 16628 Prague (Czech Republic)

    2016-03-15

    A set of zinc-silicate glasses with different ratios of erbium and ytterbium was fabricated. To achieve Ag-rich thin films in a sub-surface layer, ion-implantation technique at an energy of 1.2 MeV and 1.7 MeV with a fluence of 1 × 10{sup 16} cm{sup −2} was used. Post-implantation annealing was also applied. Changes in the spectroscopic and lasing properties of erbium ions as a function of implantation fluence of silver were studied with the aim to assess the positive effect of silver as a sensitiser of erbium luminescence. Therefore, absorption spectra in the visible range as well as luminescence spectra in the near-infrared range were measured and partially also the {sup 4}I{sub 11/2}–{sup 4}I{sub 15/2} transition of the erbium ion was studied. The results showed that silver positively influenced luminescence intensity at 1530 nm by increasing it almost three times. The biggest increase was achieved in glass with the highest concentration of erbium. Luminescence lifetime was not significantly influenced by the presence of silver and still remained around 10 ms.

  19. Do soft drinks affect metal ions release from orthodontic appliances?

    Science.gov (United States)

    Mikulewicz, Marcin; Wołowiec, Paulina; Loster, Bartłomiej W; Chojnacka, Katarzyna

    2015-01-01

    The effect of orange juice and Coca Cola(®) on the release of metal ions from fixed orthodontic appliances. A continuous flow system designed for in vitro testing of orthodontic appliances was used. Orange juice/Coca Cola(®) was flowing through the system alternately with artificial saliva for 5.5 and 18.5h, respectively. The collected samples underwent a multielemental ICP-OES analysis in order to determine the metal ions release pattern in time. The total mass of ions released from the appliance into orange juice and Coca Cola(®) (respectively) during the experiment was calculated (μg): Ni (15.33; 37.75), Cr (3.604; 1.052), Fe (48.42; ≥ 156.1), Cu (57.87, 32.91), Mn (9.164; 41.16), Mo (9.999; 30.12), and Cd (0.5967; 2.173). It was found that orange juice did not intensify the release of metal ions from orthodontic appliances, whereas Coca Cola(®) caused increased release of Ni ions. Copyright © 2015 Elsevier GmbH. All rights reserved.

  20. Silver nanoparticle release from commercially available plastic food containers into food simulants

    DEFF Research Database (Denmark)

    Mackevica, Aiga; Olsson, Mikael Emil; Hansen, Steffen Foss

    2016-01-01

    . In the current study, we investigated four brands of commercially available plastic food storage containers and measured the total amount of silver, particle size and number concentration, and the migration rates into three different food simulants (Milli-Q grade water, 10 % ethanol, and 3 % acetic acid) for 10...... days at 40 °C. The experimental setup was made according to the European Commission Directive (EU 10/2011) for articles intended to be in contact with food. The total amount of silver in plastic containers and migration solutions was quantified by ICP-MS analysis, and the size of the migrated particles...... was investigated by single particle ICP-MS and TEM-EDS. The total mass and median size of released particulate Ag were generally highest in 3 % acetic acid for three out of four food container brands. The total content of silver in the containers varied from 13 to 42 µg/g. The highest migration was observed...

  1. The formation of silver metal nanoparticles by ion implantation in silicate glasses

    Czech Academy of Sciences Publication Activity Database

    Vytykačová, S.; Švecová, B.; Nekvindová, P.; Špirková, J.; Macková, Anna; Mikšová, Romana; Bottger, R.

    2016-01-01

    Roč. 371, MAR (2016), s. 245-255 ISSN 0168-583X. [22nd International conference on Ion Beam Analysis (IBA). Opatija, 14.06.2015-19.06.2015] R&D Projects: GA MŠk(CZ) LM2011019; GA ČR GA15-01602S Institutional support: RVO:61389005 Keywords : silicate glasses * silver nanoparticles * ion implantation Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.109, year: 2016

  2. The reactivity study of peptide A3-capped gold and silver nanoparticles with heavy metal ions

    International Nuclear Information System (INIS)

    Yang, Hongyu; Tang, Zhenghua; Wang, Likai; Zhou, Weijia; Li, Ligui; Zhang, Yongqing; Chen, Shaowei

    2016-01-01

    Highlights: • Apparent color change upon the addition of Hg"2"+ or As"3"+ ions into A3-AuNPs solution. • Distinct color change of A3-AgNPs solution only in the presence of Hg"2"+ ions. • The Hg"2"+ concentration limit of A3-AgNPs about 40 times lower than A3-AuNPs. • Based on the DLS, TEM and XPS results, two reaction mechanisms have been proposed. - Abstract: Peptide A3-capped gold and silver nanoparticles were prepared by chemical reduction of metal salt precursors. The nanoparticles exhibited apparent but distinctly different color changes upon the addition of selected heavy metal ions. For gold nanoparticles, the solution color was found to change from red to blue in the presence of Hg"2"+ or As"3"+ ions, accompanied with broadening and a red-shift of the surface plasmon resonance peak. In contrast, silver nanoparticles showed an apparent color change from yellow to colorless only in the presence of Hg"2"+, along with a blue-shift and diminishment of the surface plasmon resonance peak. The Hg"2"+ reaction concentration limit of silver nanoparticle was about 40 times lower than that of gold nanoparticle. Based on the dynamic light scattering, transmission electron microscopy and X-ray photoelectron spectroscopic results, the reaction mechanism has been proposed. Such a sensitive variation of the nanoparticle optical properties to selective ions might be exploited for ion detection for potential applications.

  3. Unraveling the reaction mechanism of silver ions reduction by chitosan from so far neglected spectroscopic features.

    Science.gov (United States)

    Carapeto, Ana Patrícia; Ferraria, Ana Maria; do Rego, Ana Maria Botelho

    2017-10-15

    Metallic silver nanoparticles were synthesized in aqueous solution using chitosan, as both reducing and stabilizing agent, and AgNO 3 as silver precursor aiming the production of solid ultra-thin films. A systematic characterization of the resulting system as a function of the initial concentrations was performed. The combination of UV-vis absorption - and its quantitative analysis - with X-ray photoelectron spectra, light scattering measurements and atomic force microscopy allowed obtaining a rational picture of silver reduction mechanism through the identification of the nature of the formed reduced/oxidized species. Nanoparticle mean sizes and sizes distributions were rather independent from the precursors initial absolute and relative concentrations ([AgNO 3 ]/[chitosan]). This work clarifies some points of the mechanism involved showing experimental evidence of the early stages of the very fast silver reduction in chitosan aqueous solutions through the spectral signature of the smallest silver aggregate (Ag 2 + ) even at room temperature. The characterized system is believed to be useful for research fields where silver nanoparticles completely exempt of harmful traces of inorganic ions, coming from additional reducing agents, are needed, especially to be used in biocompatible in films. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Toxicogenomic study in rat thymus of F1 generation offspring following maternal exposure to silver ion

    Directory of Open Access Journals (Sweden)

    Xiugong Gao

    2015-01-01

    Full Text Available Male and female rats (26-day-old were exposed to 0.0, 0.4, 4 or 40 mg/kg body weight silver acetate (AgAc in drinking water for 10 weeks prior to and during mating. Sperm-positive females remained within their dose groups and were exposed to silver acetate during gestation and lactation. At postnatal day 26, the effect of silver ions on the developing F1 generation rat thymus was evaluated at the transcriptional level using whole-genome microarrays. Gene expression profiling analyses identified a dozen differentially expressed genes (DEGs in each dose group using a loose criterion of fold change (FC >1.5 and unadjusted p < 0.05, regardless of whether the analysis was conducted within each gender group or with both gender groups combined. No dose-dependent effect was observed on the number of DEGs. In addition, none of these genes had a false discovery rate (FDR <0.05 after correction for multiple testing. These results in combination with the observation that thymus-to-body-weight ratios were not affected and no histopathological abnormalities were identified indicate that in utero exposure to silver ions up to 26.0 mg/kg (equivalent to 40.0 mg/kg silver acetate did not have an adverse effect on the developing thymus.

  5. Combined use of an ibuprofen-releasing foam dressing and silver dressing on infected leg ulcers

    DEFF Research Database (Denmark)

    Jorgensen, B.; Gottrup, F.; Karlsmark, T.

    2008-01-01

    OBJECTIVE: To investigate the effect and safety of an ibuprofen-releasing foam (Biatain-Ibu, Coloplast A/S) combined with an ionised silver-releasing wound contact layer (Physiotulle Ag, Coloplast A/S) on painful, infected venous leg ulcers. METHOD: This open non-comparative study involved 24...... patients with painful, exuding, locally infected, and stalled venous leg ulcers. Persistent pain and pain at dressing change were monitored using a 11-point numerical box scale (NBS). The composition of the wound bed, the dressing combination's ability to absorb exudate and minimise leakage, ibuprofen...... dressing application, the mean concentration of ibuprofen in the wound exudate reached a constant level of 35 +/- 21 microg/ml.After 31 days, the relative wound area had reduced by 42%, with an associated decrease in fibrin and an increase in granulation tissue.The number of patients with wound malodour...

  6. Energy distribution of ions produced by laser ablation of silver in vacuum

    DEFF Research Database (Denmark)

    Christensen, Bo Toftmann; Schou, Jørgen; Canulescu, Stela

    2013-01-01

    the ablation process. A silver target in vacuum was irradiated with a Nd:YAG laser at a wavelength of 355nm and detailed measurements of the time-resolved angular distribution of plume ions were made. In contrast to earlier work, the beam spot was circular such that any flip-over effect of the plume is avoided......The ion energy in a silver ablation plume for fluence in the range of 0.6–2.4Jcm−2, typical for a pulsed laser deposition (PLD) experiment has been investigated. In this fluence range the ion fraction of the ablated particles becomes gradually dominant and can be utilized to characterize...

  7. Highly selective and sensitive fluorescent chemosensor for femtomolar detection of silver ion in aqueous medium

    Directory of Open Access Journals (Sweden)

    Abraham Daniel Arulraj

    2015-12-01

    Full Text Available The chemical sensing for the trace level detection of silver ion in aqueous solution still remains a challenge using simple, rapid, and inexpensive method. We report that thionine can be used as a fluorescent probe for the detection of Ag+ ion. The successive addition of Ag+ ion to the solution containing thionine quenches (turns-off the fluorescence intensity of thionine. Association and quenching constants have been estimated by the Benesi–Hildebrand method and Stern–Volmer plot, respectively. From the plot, the nature of the fluorescence quenching was confirmed as static quenching. An important feature of our chemosensor is high selectivity towards the determination of silver ion in aqueous solution over the other competitive metal ions. The detection limit of the sensor achieved 5 fM for Ag+ ion, which is superior to all previously reported chemosensors. The NMR and FT-IR studies were also carried out to support the complex formation between thionine and Ag+ ion. The practicality of the proposed chemosensor for determination of Ag+ ion was carried in untreated water samples.

  8. Study of ion-bombardment-induced surface topography of silver by stereophotogrammetric method

    International Nuclear Information System (INIS)

    Fayazov, I.M.; Sokolov, V.N.

    1992-01-01

    The ion-bombardment-induced surface topography of polycrystalline silver was studied using the stereophotogrammetric method. The samples were irradiated with 30keV argon ions at fairly high fluences (> 10 17 ions/cm 2 ). The influence of the inclination angle of the sample in the SEM on the cone shape of a SEM-picture is discussed. To analyse the irradiated surfaces covered with cones, the SEM-stereotechnique is proposed. The measurements of the sample section perpendicular to the incidence plane are also carried out. (author)

  9. Time-resolved angular distributions of plume ions from silver at low and medium laser fluence

    DEFF Research Database (Denmark)

    Christensen, Bo Toftmann; Schou, Jørgen

    Even at moderate fluence (0.6 -2.4 J/cm2) laser impact on metals in the UV regime results in a significant number of ions emitted from the surface. The ablated particles are largely neutrals at the lowest fluence, but the fraction of ions increases strongly with fluence. We have irradiated silver...... in a vacuum chamber (~ 10-7 mbar) with a Nd:YAG laser at a wavelength of 355 nm and made detailed measurements of the time-resolved angular distribution. The ion flow in different directions has been measured with a hemispherical array of Langmuir probes, by which the time-of-flight spectra, as well...

  10. Existence, release, and antibacterial actions of silver nanoparticles on Ag–PIII TiO2 films with different nanotopographies

    Directory of Open Access Journals (Sweden)

    Li J

    2014-07-01

    Full Text Available Jinhua Li, Yuqin Qiao, Hongqin Zhu, Fanhao Meng, Xuanyong Liu State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, People’s Republic of China Abstract: Nanotopographical TiO2 films (including nanorod, nanotip, and nanowire topographies were successfully fabricated on the metallic Ti surface via hydrothermal treatment and then underwent Ag plasma immersion ion implantation to incorporate Ag with TiO2. The surface morphology, phase component, and chemical composition before and after Ag–PIII were characterized. In view of the potential clinical applications, both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus were used to estimate their antimicrobial effect. The nanostructured TiO2 films on a Ti surface exhibit a better bacteriostatic effect on both microbes compared to the pristine Ti. The nanotopographies of the TiO2 films affect the nucleation, growth, and distribution of Ag nanoparticles in the films during Ag–PIII process. The Ag nanoparticles are completely embedded into the nanorod film while partially exposed out of the nanotip and nanowire films, which account for the significant differences in the release behaviors of Ag ions in vitro. However, no significant difference exists in their antimicrobial activity against both microbes. The antimicrobial actions of the Ag@TiO2 system described here consist of two methods – the contact-killing action and the release-killing action. Nevertheless, based on the observed results, the contact-killing action should be regarded as the main method to destroy microbes for all the Ag plasma-modified TiO2 nanofilms. This study provides insight to optimize the surface design of Ti-based implants to acquire more effective antimicrobial surfaces to meet clinical applications. Keywords: silver, nanoparticles, titania, nanostructure, antibacterial, plasma

  11. Flotation of traces of silver and copper(II) ions with a methyl cellosolve solution of dithizone.

    Science.gov (United States)

    Hiraide, M; Mizuike, A

    1975-06-01

    Microgram quantities of silver and copper(II) ions in aqueous solutions are collected on dithizone precipitates, which are then floated with the aid of small nitrogen bubbles. This separation technique has been successfully applied to the atomic-absorption spectrophotometric determination of down to a tenth ppm of silver and copper in high-purity lead and zinc metals.

  12. A facile method to prepare fluorescent carbon dots and their application in selective colorimetric sensing of silver ion through the formation of silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ayaz Ahmed, Khan Behlol; P, Suresh Kumar; Veerappan, Anbazhagan, E-mail: anbazhagan@scbt.sastra.edu

    2016-09-15

    Herein, we report a laboratory convenient method for the preparation of blue color emitting fluorescent carbon dots (C-dots) in 60 min by boiling the alkaline solution of pectin. The C-dots derived from pectin detects selectively silver ion by forming silver nanoparticles (AgNPs) without any irradiation or heating or additional reducing agents. As prepared AgNPs appears yellow in color and showed the characteristic surface plasmon resonance maximum at 410 nm. Transmission electron microscopy (TEM) revealed crystalline, spherical AgNPs with size range from 10–15 nm. Cyclic voltammetry study revealed that the lower reduction potential of C-dots than that of silver ion favors the reduction of Ag{sup +} to Ag°. Electrochemical impedance spectroscopy showed the charge transfer value for the redox reaction of C-dots as 200 Ωcm{sup 2}. In the presence of Ag{sup +}, C-dots fluorescence emission was turned from blue to cyan to green to colorless, accompanying the quenching and red shift in emission maximum at 450 nm. Interference study clearly showed that the C-dots have high preference for Ag{sup +} ion than the other interfering metal ions. The proposed sensor system selectively senses Ag{sup +} ion in water at micromolar concentration and also offers an easy procedure to prepare AgNPs in the presence of other interfering metal ions. - Highlights: • Blue color emitting C-dots was prepared by boiling alkaline pectin solution. • C-dots sense silver ion at micromolar concentration. • C-dots recognize silver ion in the presence of interfering metal ions. • Reduction potential of C-dots was estimated by cyclic voltammeter as – 0.2 V.

  13. Bioaccumulation of silver in Daphnia magna:Waterborne and dietary exposure to nanoparticles and dissolved silver

    NARCIS (Netherlands)

    Ribeiro, Fabianne; van Gestel, C.A.M.; Pavlaki, M.D.; Azevedo, S.; Soares, A.M.V.M.; Loureiro, S.

    2017-01-01

    Silver nanoparticles (Ag-NP) are incorporated into commercial products as antimicrobial agents, which potentiate their emission to the environment. The toxicity of Ag-NP has been associated with the release of Ag ions (Ag

  14. Ion induced transformation of polymer films into diamond-like carbon incorporating silver nano particles

    International Nuclear Information System (INIS)

    Schwarz, Florian P.

    2010-01-01

    Silver containing diamond-like carbon (DLC) is an interesting material for medical engineering from several points of view. On the one hand DLC provides high mechanical robustness. It can be used as biocompatible and wear resistant coating for joint replacing implants. On the other hand silver has antimicrobial properties, which could reduce post-operative inflammations. However conventional production of Ag-DLC by co-deposition of silver and carbon in a plasma process is problematic since it does not allow for a separate control of nano particle morphology and matrix properties. In this work an alternative production method has been developed to circumvent this problem. In metall-DLC-production by ion implantation into a nano composite, silver nano particles are initially formed in solution and then incorporated within a polymer matrix. Finally the polymer is transformed into DLC by ion implantation. The aspects and single steps of this method were investigated with regard to the resulting material's properties. The goal was to design an economically relevant deposition method. Based on experimental results a model of the transformation process has been established, which has also been implemented in a computer simulation. Finally the antibacterial properties of the material have been checked in a biomedical test. Here a bacterial killing rate of 90% could be achieved. (orig.)

  15. Silver nanocluster formation in ion-exchanged glasses by annealing, ion beam and laser beam irradiation: An EXAFS study

    International Nuclear Information System (INIS)

    Battaglin, G.; Cattaruzza, E.; Gonella, F.; Polloni, R.; D'Acapito, F.; Colonna, S.; Mattei, G.; Maurizio, C.; Mazzoldi, P.; Padovani, S.; Sada, C.; Quaranta, A.; Longo, A.

    2003-01-01

    Extended X-ray absorption fine structure analysis is used to determine the silver local environment in silicate glasses doped by the Ag-alkali ion-exchange process, followed by different treatments, namely, ion irradiation, thermal annealing in reducing atmosphere, laser irradiation. The obtained results indicate that metal nanocluster composites with different cluster structures may be formed with these multistep methodologies, pointing out the role of the preparation parameters in giving rise to different features. Lattice parameters and cluster diameter were determined by grazing incidence X-ray diffraction

  16. The influence of silver-ion doping using ion implantation on the luminescence properties of Er–Yb silicate glasses

    Czech Academy of Sciences Publication Activity Database

    Staněk, S.; Nekvindová, P.; Švecová, B.; Vytykáčová, S.; Míka, M.; Oswald, Jiří; Macková, Anna; Malinský, Petr; Špirková, J.

    2016-01-01

    Roč. 371, Mar (2016), s. 350-354 ISSN 0168-583X. [22nd International conference on Ion Beam Analysis (IBA). Opatija, 14.06.2015-19.06.2015] R&D Projects: GA MŠk LM2015056; GA ČR GA15-01602S Institutional support: RVO:68378271 ; RVO:61389005 Keywords : ion implantation * silicate glass * silver * nanoparticles * erbium Subject RIV: BM - Solid Matter Physics ; Magnetism; BG - Nuclear, Atomic and Molecular Physics, Colliders (UJF-V) Impact factor: 1.109, year: 2016

  17. Fabrication of Conductive Nanostructures by Femtosecond Laser Induced Reduction of Silver Ions

    Science.gov (United States)

    Barton, Peter G.

    Nanofabrication through multiphoton absorption has generated considerable interest because of its unique ability to generate 2D and 3D structures in a single laser-direct-write step as well as its ability to generate feature sizes well below the diffraction limited laser spot size. The majority of multiphoton fabrication has been used to create 3D structures of photopolymers which have applications in a wide variety of fields, but require additional post-processing steps to fabricate conductive structures. It has been shown that metal ions can also undergo multiphoton absorption, which reduces the metal ions to stable atoms/nanoparticles which are formed at the laser focal point. When the focus is located at the substrate surface, the reduced metal is deposited on the surface, which allows arbitrary 2D patterning as well as building up 3D structures from this first layer. Samples containing the metal ions can be prepared either in a liquid solution, or in a polymer film. The polymer film approach has the benefit of added support for the 3D metallic structures; however it is difficult to remove the polymer after fabrication to leave a free standing metallic structure. With the ion solution method, free standing metallic structures can be fabricated but need to be able to withstand surface tension forces when the remaining unexposed solution is washed away. So far, silver nanowires with resistivity on the order of bulk silver have been fabricated, as well as a few small 3D structures. This research focuses on the surfactant assisted multiphoton reduction of silver ions in a liquid solution. The experimental setup consists of a Coherent Micra 10 Ultrafast laser with 30fs pulse length, 80MHz repetition rate, and a wavelength centered at 800nm. This beam is focused into the sample using a 100x objective with a N.A. of 1.49. Silver structures such as nanowires and grid patterns have been produced with minimum linewidth of 180nm. Silver nanowires with resistivity down to

  18. Ab initio determination of ion traps and the dynamics of silver in silver-doped chalcogenide glass

    International Nuclear Information System (INIS)

    Chaudhuri, I.; Inam, F.; Drabold, D. A.

    2009-01-01

    We present a microscopic picture of silver dynamics in GeSe 3 :Ag glass obtained from the ab initio simulation. The dynamics of Ag is explored at two temperatures: 300 and 700 K. In the relaxed network, Ag occupies trapping centers that exist between suitably separated host sites. At 700 K, Ag motion proceeds via a trapping-release dynamics between 'supertraps' or cages consisting of multiple trapping center sites in a small volume. Our work offers a first-principles identification of trapping centers invoked in current theories, with a description of their properties and associated Ag dynamics. We compute the charge state of the Ag in the network and show that it is neutral if weakly bonded and Ag + if in a trapping center

  19. Plasma-assisted reduction of silver ions impregnated into a natural zeolite framework

    Science.gov (United States)

    Osonio, Airah P.; Vasquez, Magdaleno R.

    2018-02-01

    A green, dry, and energy-efficient method for the fabrication of silver-zeolite (AgZ) composite via 13.56 MHz radio-frequency plasma reduction is demonstrated. Impregnation by soaking and ion-exchange deposition were performed to load the silver ions (Ag+) into the sodium-zeolite samples. Characterization was performed by optical emission spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller analyses. Results indicate the successful reduction of Ag+ to its metallic state on the surface of the zeolite with a mean diameter of 165 nm. This plasma-induced reduction technique opens possibilities in several areas including catalysis, adsorption, water treatment, and medicine.

  20. Antibacterial TiO2Coating Incorporating Silver Nanoparticles by Micro arc Oxidation and Ion Implantation

    International Nuclear Information System (INIS)

    Zhang, P.; Zhang, Z.; Li, W.

    2013-01-01

    Infection associated with titanium implants remains the most common serious complication in hard tissue replacement surgery. Since such postoperative infections are usually difficult to cure, it is critical to find optimal strategies for preventing infections. In this study, TiO 2 coating incorporating silver (Ag) nanoparticles were fabricated on pure titanium by micro arc oxidation and ion implantation. The antibacterial activity was evaluated by exposing the specimens to Staphylococcus aureus and comparing the reaction of the pathogens to Ti-MAO-Ag with Ti-MAO controls. Ti-MAO-Ag clearly inhibited bacterial colonization more than the control specimen. The coating’s antibacterial ability was enhanced by increasing the dose of silver ion implantation, and Ti-MAO-Ag 20.0 had the best antibacterial ability. In addition, cytocompatibility was assessed by culturing cell colonies on the specimens. The cells grew well on both specimens. These findings indicate that surface modification by means of this process combining MAO and silver ion implantation is useful in providing antibacterial activity and exhibits cytocompatibility with titanium implants

  1. The reactivity study of peptide A3-capped gold and silver nanoparticles with heavy metal ions

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Hongyu [New Energy Research Institute, School of Environment and Energy, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou 510006 (China); Tang, Zhenghua, E-mail: zhht@scut.edu.cn [New Energy Research Institute, School of Environment and Energy, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou 510006 (China); Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control, School of Environment and Energy, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou 510006 (China); Wang, Likai; Zhou, Weijia; Li, Ligui [New Energy Research Institute, School of Environment and Energy, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou 510006 (China); Zhang, Yongqing [Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control, School of Environment and Energy, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou 510006 (China); Chen, Shaowei, E-mail: shaowei@ucsc.edu [New Energy Research Institute, School of Environment and Energy, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou 510006 (China); Department of Chemistry and Biochemistry, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States)

    2016-08-15

    Highlights: • Apparent color change upon the addition of Hg{sup 2+} or As{sup 3+} ions into A3-AuNPs solution. • Distinct color change of A3-AgNPs solution only in the presence of Hg{sup 2+} ions. • The Hg{sup 2+} concentration limit of A3-AgNPs about 40 times lower than A3-AuNPs. • Based on the DLS, TEM and XPS results, two reaction mechanisms have been proposed. - Abstract: Peptide A3-capped gold and silver nanoparticles were prepared by chemical reduction of metal salt precursors. The nanoparticles exhibited apparent but distinctly different color changes upon the addition of selected heavy metal ions. For gold nanoparticles, the solution color was found to change from red to blue in the presence of Hg{sup 2+} or As{sup 3+} ions, accompanied with broadening and a red-shift of the surface plasmon resonance peak. In contrast, silver nanoparticles showed an apparent color change from yellow to colorless only in the presence of Hg{sup 2+}, along with a blue-shift and diminishment of the surface plasmon resonance peak. The Hg{sup 2+} reaction concentration limit of silver nanoparticle was about 40 times lower than that of gold nanoparticle. Based on the dynamic light scattering, transmission electron microscopy and X-ray photoelectron spectroscopic results, the reaction mechanism has been proposed. Such a sensitive variation of the nanoparticle optical properties to selective ions might be exploited for ion detection for potential applications.

  2. Separation and measurement of silver nanoparticles and silver ions using magnetic particles

    Science.gov (United States)

    The recent surge in consumer products and applications using metallic nanoparticles has increased the possibility of human or ecosystem exposure due to unintentional release into the environment. To protect consumer health and the environment, there is an urgent need to develop t...

  3. Silver lead borate glasses doped with europium ions for phosphors ...

    Indian Academy of Sciences (India)

    2017-07-25

    Jul 25, 2017 ... C. The investigation of Fourier transformer infrared spectra shows the presence of ... around the ions, these kinds of Eu3+ doped glasses find wide range of ... is attributed to hydroxyl (OH) or water group [12]. The broad water ...

  4. Charge Transfer Based Colorimetric Detection of Silver Ion

    Energy Technology Data Exchange (ETDEWEB)

    Han, Seung Choul; Kim, Kwang Seob; Choi, Soon Kyu; Oh, Jinho; Lee, Jae Wook [Dong-A Univ., Busan (Korea, Republic of)

    2014-05-15

    We have demonstrated the colorimetric chemosensor for detection of Ag{sup +} via formation of nanoparticles which is based on the intramolecular CT interaction between the electron-rich (2,6-dialkoxynaphthalene; Np) moiety and the electron-deficient (methyl viologen; MV{sup 2+}) moiety of a single sensor molecule. Under irradiation of light, Ag{sup +} was reduced to very small silver nanoparticle by CT interaction in the presence of OEGs as flexible recognition moiety of Ag{sup +} and stabilizer for Ag nanoparticles, thus Ag nanoparticles resulted to reddish brown in the color change of sensor solution, gradually. Therefore, the charge-transfer interaction between an electron-deficient and an electron-rich units existing at a sensor molecule can be regarded as a new and efficient method to construct various colorimetric chemosensors. Donor.acceptor interactions or charge transfer (CT) interactions are an important class of non-covalent interactions and have been widely exploited in self-assembling systems. Beyond molecular chemistry, supramolecular chemistry aims at constituting highly complex, functional chemical systems from components held together by intermolecular forces. Chemosensors are the molecules of abiotic origin that bind selectively and reversibly with the analyte with concomitant change in one or more properties of the system. The recognition and signaling of ionic and neutral species of varying complexity is one of the most intensively studied areas of contemporary supramolecular chemistry.

  5. Application of silver ion in the separation of macrolide antibiotic components by high-speed counter-current chromatography.

    Science.gov (United States)

    Wen, Yaoming; Wang, Jiaoyan; Chen, Xiuming; Le, Zhanxian; Chen, Yuxiang; Zheng, Wei

    2009-05-29

    Three macrolide antibiotic components - ascomycin, tacrolimus and dihydrotacrolimus - were separated and purified by silver ion high-speed counter-current chromatography (HSCCC). The solvent system consisted of n-hexane-tert-butyl methyl ether-methanol-water (1:3:6:5, v/v) and silver nitrate (0.10mol/l). The silver ion acted as a pi-complexing agent with tacrolimus because of its extra side double bond compared with ascomycin and dihydrotacrolimus. This complexation modified the partition coefficient values and the separation factors of the three components. As a result, ascomycin, tacrolimus and dihydrotacrolimus were purified from 150mg extracted crude sample with purities of 97.6%, 98.7% and 96.5%, respectively, and yields over 80% (including their tautomers). These results cannot be achieved with the same solvent system but without the addition of silver ion.

  6. Energy distribution of ions produced by laser ablation of silver in vacuum

    International Nuclear Information System (INIS)

    Toftmann, B.; Schou, J.; Canulescu, S.

    2013-01-01

    The ion energy in a silver ablation plume for fluence in the range of 0.6–2.4 J cm −2 , typical for a pulsed laser deposition (PLD) experiment has been investigated. In this fluence range the ion fraction of the ablated particles becomes gradually dominant and can be utilized to characterize the ablation process. A silver target in vacuum was irradiated with a Nd:YAG laser at a wavelength of 355 nm and detailed measurements of the time-resolved angular distribution of plume ions were made. In contrast to earlier work, the beam spot was circular such that any flip-over effect of the plume is avoided. The angular energy distribution of ions in forward direction exceeds values of 500 eV, while at large angles the ion energy tail is below 100 eV. The maximum for the time-of-flight distributions agrees consistently with the prediction of Anisimov's model in the low fluence range, in which hydrodynamic motion prevails.

  7. Investigation of corrosion and ion release from titanium dental implant

    International Nuclear Information System (INIS)

    Ektessabi, A.M.; Mouhyi, J.; Louvette, P.; Sennerby, L.

    1997-01-01

    A thin passive titanium dioxide, in its stoichiometric form, has a very high corrosion resistance, but the same conclusion can not be made on corrosion resistance of a surface which is not stoichiometrically titanium dioxide, or even a surface which is a composition of various elements and oxides. In practice, the implants available on the market have an oxide surface contaminated with other elements. The aim of this paper is to correlate clinical observations that show the deterioration of Ti made implants after certain period of insertion in the patients, and in vitro corrosion resistance of Ti implants with surface passive oxide layer. For this purpose, surface analysis of the retrieved failed implants were performed and in vivo animal experiments with relation to ion release from implants were done. Finally, on the basis of the clinical observation, in vivo animal test, and in vitro electrochemical corrosion test, a model is proposed to explain the corrosion and ion release from the Ti implant. (author)

  8. Two-stage DNA compaction induced by silver ions suggests a cooperative binding mechanism

    Science.gov (United States)

    Jiang, Wen-Yan; Ran, Shi-Yong

    2018-05-01

    The interaction between silver ions and DNA plays an important role in the therapeutic use of silver ions and in related technologies such as DNA sensors. However, the underlying mechanism has not been fully understood. In this study, the dynamics of Ag+-DNA interaction at a single-molecule level was studied using magnetic tweezers. AgNO3 solutions with concentrations ranging from 1 μM to 20 μM led to a 1.4-1.8 μm decrease in length of a single λ-DNA molecule, indicating that Ag+ has a strong binding with DNA, causing the DNA conformational change. The compaction process comprises one linear declining stage and another sigmoid-shaped stage, which can be attributed to the interaction mechanism. Considering the cooperative effect, the sigmoid trend was well explained using a phenomenological model. By contrast, addition of silver nanoparticle solution induced no detectable transition of DNA. The dependence of the interaction on ionic strength and DNA concentration was examined via morphology characterization and particle size distribution measurement. The size of the Ag+-DNA complex decreased with an increase in Ag+ ionic strength ranging from 1 μM to 1 mM. Morphology characterization confirmed that silver ions induced DNA to adopt a compacted globular conformation. At a fixed [AgNO3]:[DNA base pairs] ratio, increasing DNA concentration led to increased sizes of the complexes. Intermolecular interaction is believed to affect the Ag+-DNA complex formation to a large extent.

  9. Silver nanoparticles in blends of polyethylene and a superabsorbent polymer: morphology and silver ion release

    Czech Academy of Sciences Publication Activity Database

    Stará, Hana; Starý, Z.; Münstedt, H.

    2011-01-01

    Roč. 296, č. 5 (2011), s. 423-427 ISSN 1438-7492 Institutional research plan: CEZ:AV0Z40500505 Keywords : electron microscopy * morphology * nanoparticles Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.986, year: 2011

  10. Polyurethane/silver-nanocomposites with enhanced silver ion release using multifunctional invertible polyesters

    Czech Academy of Sciences Publication Activity Database

    Triebel, Ch.; Vasylyev, S.; Damm, C.; Stará, Hana; Özpinar, C.; Hausmann, S.; Peukert, W.; Münstedt, H.

    2011-01-01

    Roč. 21, č. 12 (2011), s. 4377-4383 ISSN 0959-9428 Institutional research plan: CEZ:AV0Z40500505 Keywords : antimicrobial activity * nanoparticles * infections Subject RIV: CD - Macromolecular Chemistry Impact factor: 5.968, year: 2011

  11. Large scale silver nanowires network fabricated by MeV hydrogen (H+) ion beam irradiation

    International Nuclear Information System (INIS)

    S, Honey; S, Naseem; A, Ishaq; M, Maaza; M T, Bhatti; D, Wan

    2016-01-01

    A random two-dimensional large scale nano-network of silver nanowires (Ag-NWs) is fabricated by MeV hydrogen (H + ) ion beam irradiation. Ag-NWs are irradiated under H +  ion beam at different ion fluences at room temperature. The Ag-NW network is fabricated by H + ion beam-induced welding of Ag-NWs at intersecting positions. H +  ion beam induced welding is confirmed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Moreover, the structure of Ag NWs remains stable under H +  ion beam, and networks are optically transparent. Morphology also remains stable under H +  ion beam irradiation. No slicings or cuttings of Ag-NWs are observed under MeV H +  ion beam irradiation. The results exhibit that the formation of Ag-NW network proceeds through three steps: ion beam induced thermal spikes lead to the local heating of Ag-NWs, the formation of simple junctions on small scale, and the formation of a large scale network. This observation is useful for using Ag-NWs based devices in upper space where protons are abandoned in an energy range from MeV to GeV. This high-quality Ag-NW network can also be used as a transparent electrode for optoelectronics devices. (paper)

  12. Large third-order optical nonlinearity of silver colloids in silica glasses synthesized by ion implantation

    International Nuclear Information System (INIS)

    Ghosh, Binita; Chakraborty, Purushottam

    2011-01-01

    Silver ion implantations in fused silica glasses have been made to synthesize silver nanocluster-glass composites and a combination of 'Anti-Resonant Interferometric Nonlinear Spectroscopy (ARINS)' and 'Z-scan' techniques has been employed for the measurement of the third-order optical susceptibility of these nanocomposites. The ARINS technique utilizes the dressing of two unequal-intensity counter-propagating pulsed optical beams with differential nonlinear phases, which occurs upon traversing the sample. This difference in phase manifests itself in the intensity-dependent transmission, measurement of which enables us to extract the values of nonlinear refractive index (η 2 ) and nonlinear absorption coefficient (β), finally yielding the real and imaginary parts of the third-order dielectric susceptibility (χ (3) ). The real and imaginary parts of χ (3) are obtained in the orders of 10 -10 e.s.u for silver nanocluster-glass composites. The present value of χ (3) , to our knowledge, is extremely accurate and much more reliable compared to the values previously obtained by other workers for similar silver-glass nanocomposites using only Z-scan technique. Optical nonlinearity has been explained to be due to two-photon absorption in the present nanocomposite glasses and is essentially of electronic origin.

  13. Formation of silver colloids on ion exchanged soda lime silicate glasses by irradiation

    International Nuclear Information System (INIS)

    Yoshimura, E.M.; Okuno, E.

    1998-01-01

    The effect of ionizing radiation (gamma rays, X-rays and electrons) on soda lime silicate glasses, in which part of the Na + was substituted by Ag + by means of an ionic exchange process, was studied. The techniques of thermally stimulated depolarization current (TSDC) and transmission electron microscopy (TEM) were employed to follow the formation of silver colloids by irradiation. Also the thermoluminescence (TL) of the samples was measured and three peaks between room temperature and 450 C were observed. The TEM and TSDC results agree that, as expected, ionizing radiation promotes the formation of silver colloids on the ion exchanged surface of soda lime glasses. Soft X-rays are much more efficient in the process than gamma rays and electrons. The correlation with thermoluminescence glow curves indicates that the intensity of a TL peak at 230 C can provide a rapid means of evaluating the presence of silver colloids. TL sensitivities, measured as area under the glow curve per unit mass and unit dose, are very similar for ion exchanged and not exchanged samples submitted to X-ray irradiation, although the peak temperatures differ in about 40 C in the two cases. For both electron and gamma irradiated samples, the TL sensitivity drops about an order of magnitude when compared to the X-ray irradiated ones. (orig.)

  14. Optical and Electrical Characteristics of Silver Ion Conducting Nanocomposite Solid Polymer Electrolytes Based on Chitosan

    Science.gov (United States)

    Aziz, Shujahadeen B.; Rasheed, Mariwan A.; Abidin, Zul H. Z.

    2017-10-01

    Optical and electrical properties of nanocomposite solid polymer electrolytes based on chitosan have been investigated. Incorporation of alumina nanoparticles into the chitosan:silver triflate (AgTf) system broadened the surface plasmon resonance peaks of the silver nanoparticles and shifted the absorption edge to lower photon energy. A clear decrease of the optical bandgap in nanocomposite samples containing alumina nanoparticles was observed. The variation of the direct-current (DC) conductivity and dielectric constant followed the same trend with alumina concentration. The DC conductivity increased by two orders of magnitude, which can be attributed to hindrance of silver ion reduction. Transmission electron microscopy was used to interpret the space-charge and blocking effects of alumina nanoparticles on the DC conductivity and dielectric constant. The ion conduction mechanism was interpreted based on the dependences of the electrical and dielectric parameters. The dependence of the DC conductivity on the dielectric constant is explained empirically. Relaxation processes associated with conductivity and viscoelasticity were distinguished based on the incomplete semicircular arcs in plots of the real and imaginary parts of the electric modulus.

  15. Silver nanoclusters-assisted ion-exchange reaction with CdTe quantum dots for photoelectrochemical detection of adenosine by target-triggering multiple-cycle amplification strategy.

    Science.gov (United States)

    Zhao, Yang; Tan, Lu; Gao, Xiaoshan; Jie, Guifen; Huang, Tingyu

    2018-07-01

    Herein, we successfully devised a novel photoelectrochemical (PEC) platform for ultrasensitive detection of adenosine by target-triggering cascade multiple cycle amplification based on the silver nanoparticles-assisted ion-exchange reaction with CdTe quantum dots (QDs). In the presence of target adenosine, DNA s1 is released from the aptamer and then hybridizes with hairpin DNA (HP1), which could initiate the cycling cleavage process under the reaction of nicking endonuclease. Then the product (DNA b) of cycle I could act as the "DNA trigger" of cycle II to further generate a large number of DNA s1, which again go back to cycle I, thus a cascade multiple DNA cycle amplification was carried out to produce abundant DNA c. These DNA c fragments with the cytosine (C)-rich loop were captured by magnetic beads, and numerous silver nanoclusters (Ag NCs) were synthesized by AgNO 3 and sodium borohydride. The dissolved AgNCs released numerous silver ions which could induce ion exchange reaction with the CdTe QDs, thus resulting in greatly amplified change of photocurrent for target detection. The detection linear range for adenosine was 1.0 fM ~10 nM with the detection limit of 0.5 fM. The present PEC strategy combining cascade multiple DNA cycle amplification and AgNCs-induced ion-exchange reaction with QDs provides new insight into rapid, and ultrasensitive PEC detection of different biomolecules, which showed great potential for detecting trace amounts in bioanalysis and clinical biomedicine. Copyright © 2018 Elsevier B.V. All rights reserved.

  16. Organic SIMS: the influence of time on the ion yield enhancement by silver and gold deposition

    Science.gov (United States)

    Adriaensen, L.; Vangaever, F.; Gijbels, R.

    2004-06-01

    A series of organic dyes and pharmaceuticals was used to study the secondary ion yield enhancement by metal deposition. The molecules were dissolved in methanol and spincasted on silicon substrates. Subsequently, silver or gold was evaporated on the samples to produce a very thin coating. The coated samples, when measured with TOF-SIMS, showed a considerable increase in characteristic secondary ion intensity. Gold-evaporated samples appear to exhibit the highest signal enhancement. These observations apply to organic samples in general, an advantage that allows to use the technique of metal deposition on real-world samples. However, the observed signal increase does not occur at any given moment. The time between metal deposition on the sample surface and the measuring of the sample with TOF-SIMS appears to have an important influence on the enhancement of the secondary ion intensities. In consideration of these observations several experiments were carried out, in which the spincasted samples were measured at different times after sample preparation, i.e., after gold or silver was deposited on the sample surface. The results show that, depending on the sample and the metal deposited, the secondary ion signals reach their maximum at different times. Further study will be necessary to detect the mechanism responsible for the observed enhancement effect.

  17. Chloride ion addition for controlling shapes and properties of silver nanorods capped by polyvinyl alcohol synthesized using polyol method

    Energy Technology Data Exchange (ETDEWEB)

    Junaidi, E-mail: junaidi.1982@fmipa.unila.ac.id [Department of Physics, Universitas Gadjah Mada, Yogyakarta, 55281 (Indonesia); Department of Physics, Lampung University, Bandar Lampung (Indonesia); Yunus, Muhammad, E-mail: muhammad.yunus@mail.ugm.ac.id [Department of Physics, Universitas Gadjah Mada, Yogyakarta, 55281 (Indonesia); Triyana, Kuwat, E-mail: triyana@ugm.ac.id; Harsojo,, E-mail: harsojougm@ugm.ac.id; Suharyadi, Edi, E-mail: esuharyadi@ugm.ac.id [Department of Physics, Universitas Gadjah Mada, Yogyakarta, 55281 (Indonesia); Nanomaterials Research Group, Universitas Gadjah Mada, Yogyakarta, 55281 (Indonesia)

    2016-04-19

    We report our investigation on the effect of chloride ions on controlling the shapes and properties of silver nanorods (AgNRs) synthesized using a polyol method. In this study, we used polyvinyl alcohol (PVA) as a capping agent and sodium chloride (NaCl) as a salt precursor and performed at the oil bath temperature of 140°C. The chloride ions originating from the NaCl serve to control the growth of the silver nanorods. Furthermore, the synthesized silver nanorods were characterized using SEM and XRD. The results showed that besides being able to control the growth of AgCl atoms, the chloride ions were also able to control the growth of multi-twinned-particles into the single crystalline of silver nanorods by micrometer-length. At an appropriate concentration of NaCl, the diameter of silver nanorods decreased significantly compared to that of without chloride ion addition. This technique may be useful since a particular diameter of silver nanorods affects a particular application in the future.

  18. Chloride ion addition for controlling shapes and properties of silver nanorods capped by polyvinyl alcohol synthesized by polyol method

    International Nuclear Information System (INIS)

    Junaidi; Triyana, Kuwat; Harsojo,; Suharyadi, Edi

    2016-01-01

    We report our investigation on the effect of chloride ions oncontrolling the shapes and properties of silver nanorods(AgNRs) synthesized using a polyol method. In this study, we used polyvinyl alcohol (PVA) as a capping agent and sodium chloride (NaCl) as asalt precursor and performed at the oilbath temperature of 140 °C. The chloride ions originating from the NaCl serve to control the growth of the silver nanorods. Furthermore, the synthesized silver nanorodswere characterized using UV-VIS, XRD, SEM and TEM. The results showed that besides being able to control the growth of AgCl atoms, the chloride ions were also able to control the growth of multi-twinned-particles into the single crystalline silver nanorods by micrometer-length. At an appropriate concentration of NaCl, the diameter of silver nanorodsdecreased significantly compared to that of without chloride ion addition. This technique may be useful since a particular diameter of silver nanorods affects a particular application in the future.

  19. Chloride ion addition for controlling shapes and properties of silver nanorods capped by polyvinyl alcohol synthesized using polyol method

    International Nuclear Information System (INIS)

    Junaidi; Yunus, Muhammad; Triyana, Kuwat; Harsojo,; Suharyadi, Edi

    2016-01-01

    We report our investigation on the effect of chloride ions on controlling the shapes and properties of silver nanorods (AgNRs) synthesized using a polyol method. In this study, we used polyvinyl alcohol (PVA) as a capping agent and sodium chloride (NaCl) as a salt precursor and performed at the oil bath temperature of 140°C. The chloride ions originating from the NaCl serve to control the growth of the silver nanorods. Furthermore, the synthesized silver nanorods were characterized using SEM and XRD. The results showed that besides being able to control the growth of AgCl atoms, the chloride ions were also able to control the growth of multi-twinned-particles into the single crystalline of silver nanorods by micrometer-length. At an appropriate concentration of NaCl, the diameter of silver nanorods decreased significantly compared to that of without chloride ion addition. This technique may be useful since a particular diameter of silver nanorods affects a particular application in the future.

  20. Size distribution of silver nanoclusters induced by ion, electron, laser beams and thermal treatments of an organometallic precursor

    International Nuclear Information System (INIS)

    D'Urso, L.; Nicolosi, V.; Compagnini, G.; Puglisi, O.

    2004-01-01

    Recently, a huge variety of physical and chemical synthetic processes have been reported to prepare nanostructured materials made of very small (diameter<50 nm) metallic clusters. Depending on the nature of clusters, this new kind of materials posses interesting properties (electronic, optical, magnetic, catalytic) that can be tailored as a function of the particles size and shape. Silver nanoparticles have been obtained by direct thermal treatment or by beam-enhanced decomposition (ion, electron and laser) of a silver organometallic compound (precursor) spinned onto suitable substrates. In this paper, we present the results of a study on the size distribution of such nanoparticles as a function of the different synthesis methods. It was found that the methods employed strongly affect the silver nanoparticles formation. Smaller silver nanoclusters were obtained after reduction by ion beam irradiation and thermal treatment, as observed by using different techniques (AFM, XRD and UV-Vis)

  1. Earliest Results in the Use of Activated Composite Membranes for the Transport of Silver Ions from Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Yucundo Mendoza-Tolentino

    2014-01-01

    Full Text Available This paper presents the results concerning the first use of activated composite membranes (ACMs for the facilitated transport of silver ions containing di-(2-ethylhexyl-dithiophosphoric acid (DTPA as the carrier. DTPA was immobilized by interfacial polymerization in a dense layer that was deposited in a porous layer, which was prepared on a nonwoven fabric support by phase inversion. The influence of fundamental parameters affecting the transport of silver ion as the carrier concentration in the membrane phase and stripping agent variation of the stripping solution have been studied. In the optimal conditions, the amount of silver transported across the ACMs was greater than 50%, whereas if the content of the carrier is modified, more than the 90% of the initial silver is removed from the feed phase.

  2. Silver ions increase plasma membrane permeability through modulation of intracellular calcium levels in tobacco BY-2 cells.

    Science.gov (United States)

    Klíma, Petr; Laňková, Martina; Vandenbussche, Filip; Van Der Straeten, Dominique; Petrášek, Jan

    2018-05-01

    Silver ions increase plasma membrane permeability for water and small organic compounds through their stimulatory effect on plasma membrane calcium channels, with subsequent modulation of intracellular calcium levels and ion homeostasis. The action of silver ions at the plant plasma membrane is largely connected with the inhibition of ethylene signalling thanks to the ability of silver ion to replace the copper cofactor in the ethylene receptor. A link coupling the action of silver ions and cellular auxin efflux has been suggested earlier by their possible direct interaction with auxin efflux carriers or by influencing plasma membrane permeability. Using tobacco BY-2 cells, we demonstrate here that besides a dramatic increase of efflux of synthetic auxins 2,4-dichlorophenoxyacetic acid (2,4-D) and 1-naphthalene acetic acid (NAA), treatment with AgNO 3 resulted in enhanced efflux of the cytokinin trans-zeatin (tZ) as well as the auxin structural analogues tryptophan (Trp) and benzoic acid (BA). The application of AgNO 3 was accompanied by gradual water loss and plasmolysis. The observed effects were dependent on the availability of extracellular calcium ions (Ca 2+ ) as shown by comparison of transport assays in Ca 2+ -rich and Ca 2+ -free buffers and upon treatment with inhibitors of plasma membrane Ca 2+ -permeable channels Al 3+ and ruthenium red, both abolishing the effect of AgNO 3 . Confocal microscopy of Ca 2+ -sensitive fluorescence indicator Fluo-4FF, acetoxymethyl (AM) ester suggested that the extracellular Ca 2+ availability is necessary to trigger the response to silver ions and that the intracellular Ca 2+ pool alone is not sufficient for this effect. Altogether, our data suggest that in plant cells the effects of silver ions originate from the primal modification of the internal calcium levels, possibly by their interaction with Ca 2+ -permeable channels at the plasma membrane.

  3. Aqueous dissolution of silver iodide and associated iodine release under reducing conditions with FeCl2 solution

    International Nuclear Information System (INIS)

    Inagaki, Yaohiro; Imamura, Toshitaka; Idemitsu, Kazuya; Arima, Tatsumi; Kato, Osamu; Nishimura, Tsutomu; Asano, Hidekazu

    2008-01-01

    An empirical and analytical study was performed on the aqueous dissolution of silver iodide (AgI) to release iodine under reducing conditions with Fe 2+ in order to understand the fundamental chemical and/or physical behavior of potential radioactive iodine waste forms under geological disposal conditions. Aqueous dissolution tests of AgI powder in FeCl 2 solutions (10 -6 M to 10 -3 M) were performed in a glove box purged with a gas mixture (Ar + 5% H 2 ). The test results showed that AgI dissolves to release iodine at extremely slow rates, being controlled by a diffusion process in any FeCl 2 solution. The comparison with thermodynamic calculations based on redox equilibria suggested that the AgI dissolution proceeds by redox reaction between Ag + and Fe 2+ ; however, it was far from the thermodynamic equilibrium. These results suggested that the form of AgI itself has a potential to immobilize iodine for a long time even under the disposal conditions. Solid-phase analysis for the reacted AgI by using SEM/EDS showed a certain amount of silver (maybe metallic silver) precipitated at the surface. On the basis of these results and discussion, a potential mechanism for the actual AgI dissolution was proposed as follows. The AgI dissolution proceeds by redox reaction between Ag + and Fe 2+ to release I - , which results in the precipitation of metallic silver as a reduction product of Ag + at the AgI surface to form a thin layer covering the AgI surface. The silver layer evolves to be protective against the transport of reactant species, by which the further dissolution to reach the equilibrium is suppressed. Consequently, the dissolution proceeds at extremely slow rates, being controlled by a diffusion process. (author)

  4. Bio-functionalized silver nanoparticles for selective colorimetric sensing of toxic metal ions and antimicrobial studies

    Science.gov (United States)

    Vinod Kumar, V.; Anbarasan, S.; Christena, Lawrence Rene; SaiSubramanian, Nagarajan; Philip Anthony, Savarimuthu

    2014-08-01

    Hibiscus Sabdariffa (Gongura) plant extracts (leaves (HL) and stem (HS) were used for the first time in the green synthesis of bio-functionalized silver nanoparticles (AgNPs). The bio-functionality of AgNPs has been successfully utilized for selective colorimetric sensing of potentially health and environmentally hazardous Hg2+, Cd2+ and Pb2+ metal ions at ppm level in aqueous solution. Importantly, clearly distinguishable colour for all three metal ions was observed. The influence of extract preparation condition and pH were also explored on the formation of AgNPs. Both selectivity and sensitivity differed for AgNPs synthesized from different parts of the plant. Direct correlation between the stability of green synthesized AgNPs at different pH and its antibacterial effects has been established. The selective colorimetric sensing of toxic metal ions and antimicrobial effect of green synthesized AgNPs demonstrated the multifunctional applications of green nanotechnology.

  5. Antifouling coating with controllable and sustained silver release for long-term inhibition of infection and encrustation in urinary catheters.

    Science.gov (United States)

    Wang, Rong; Neoh, Koon Gee; Kang, En-Tang; Tambyah, Paul Anantharajah; Chiong, Edmund

    2015-04-01

    Urinary tract infections constitute a large proportion of nosocomial infections, and the urinary catheter is the most important predisposing factor. Encrustation induced by urease-producing uropathogens like Proteus mirabilis causes further complications. In the present work, a strategy for controllable and sustained release of silver over several weeks has been developed for combating bacterial infection and encrustation in urinary devices. Silver nanoparticles (AgNPs) were first immobilized on polydopamine (PDA) pre-treated silicone catheter surface and this was followed by another PDA coating. The number of AgNP-PDA bilayers could be manipulated to control the amount of silver loaded and its subsequent release. Poly(sulfobetaine methacrylate-co-acrylamide) was then grafted to provide an antifouling outer layer, and to ensure free diffusion of Ag from the surface. The micron-scale combination of an antifouling coating with AgNP-PDA bilayers reduced colonization of the urinary catheter by uropathogens by approximately two orders of magnitude. With one and two AgNP-PDA bilayers, the coated catheter could resist encrustation for 12 and 45 days, respectively, compared with approximately 6 days with the Dover™ silver-coated catheter. Such anti-infective and anti-encrustation catheters can potentially have a large impact on reducing patient morbidity and healthcare expenditure. © 2014 Wiley Periodicals, Inc.

  6. MECHANICAL PROPERTIES OF PVA NANOFIBER TEXTILES WITH INCORPORATED NANODIAMONDS, COPPER AND SILVER IONS

    Directory of Open Access Journals (Sweden)

    Kateřina Indrová

    2015-02-01

    Full Text Available The unique properties of nanotextiles based on poly(vinyl-alcohol (PVA manufactured using electrospinning method have been known and exploited for many years. Recently, the enrichment of nanofiber textiles with nanoparticles, such as ions or nanodiamond particles (NDP, has become a popular way to modify the textile mechanical, chemical and physical properties. The aim of our study is to investigate the macromechanical properties of PVA nanotextiles enriched with NDP, silver (Ag and copper (Cu ions. The nanofiber textiles of a various surface weight were prepared from 16% PVA solution, while glyoxal and phosphoric acid were used as cross-linking agents. The copper and silver ions were diluted in aqueous solution and NDP were dispersed into the fibers by ultrasound homogenization. All but one set of samples were exposed to the temperature of 140 °C for 10 minutes. The samples without thermal stabilization exhibited significantly lower elastic stiffness and tensile strength. Moreover, the results of tensile testing indicate that the addition of dispersed nanoparticles has a minor effect on the mechanical properties of textiles and contributes rather to their reinforcement. On the other hand, the lack of thermal stabilization results in a poor interconnection of individual nanofiber layers and the non-stabilized textiles exhibit a lower elastic stiffness and reduced tensile strength.

  7. Nanosilver coated orthodontic brackets: in vivo antibacterial properties and ion release.

    Science.gov (United States)

    Metin-Gürsoy, Gamze; Taner, Lale; Akca, Gülçin

    2017-02-01

    Silver nanoparticles are currently utilized in the fields of dentistry. The aim of this study was to evaluate the antibacterial properties and ion release of nanosilver coated orthodontic brackets compared to conventional brackets. Nanosilver coating process was applied to standard orthodontic brackets placed on the mandibular incisors of Wistar Albino rats in the study group and conventional brackets in the control group. Dental plaque, mucosal vestibular smears, saliva, and blood samples were collected from rats at various days. The amounts of nanosilver ions in blood and saliva were measured and microbiological evaluation was made for Streptococcus mutans. For testing cariogenicity, all rats were sacrificed at the end of 75 days under anaesthesia. Teeth were stained using a caries indicator, then the caries ratio was assessed. Nanosilver coated orthodontic bracket favoured the inhibition of S.mutans on Day 30 and reduction of caries on the smooth surfaces. The nanosilver amounts in the saliva and serum samples were significantly higher in the study group on Day 7. It is suggested that nanosilver coated orthodontic brackets, as an antibacterial agent without patient compliance, could be helpful for the prevention of white spot lesions during fixed orthodontic treatment. © The Author 2016. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  8. Old tree with new shoots: silver nanoparticles for label-free and colorimetric mercury ions detection

    Science.gov (United States)

    Gao, Shuyan; Jia, Xiaoxia; Chen, Yanli

    2013-01-01

    Mercury in the environment from global mercury emissions as well as various forms of contamination poses severe threats to both human health and the environment. Long-term exposure to high levels of Hg-based toxins results in serious and irreversible damage of the central nervous system and other organs. Therefore, the development of effective sensing systems for mercury detection becomes an increasing demand. In this article, a yogurt-mediated silver nanostructure is reported to be unprecedentedly used in the naked-eye and label-free detection of mercury. The method relies on the redox reaction resulting from the electrode potential difference between Ag+/Ag (0.7996 V) and Hg2+/Hg2 2+ (0.920 V) that makes colorless Hg2+ ions which oxidize colored silver nanoparticle (AgNP) to colorless Ag+. The labor-intensive modification of AgNPs and expensive labeling are avoided, and the traditional AuNPs are substituted by AgNPs in this Hg2+ ions sensing platform, which makes it facile, low-cost, and particularly useful for home, clinic, or field applications as well as resource-limited conditions. This sensing system achieves a detection limit as low as 10 nM, lower than the toxicity level of Hg2+ ions in drinking water (30 nM) defined by World Health Organization, and exhibits excellent selectivity, largely free from the matrix effect of the real water samples. This visual label-free Hg2+ ions sensing motif shows great promise for sensing Hg2+ ions in terms of sensitivity, selectivity, cost, and maneuverability. It is also a good example for the organic combination of green chemistry and functional materials, which may trigger interest in furthering biosystems for environmental science applications.

  9. Old tree with new shoots: silver nanoparticles for label-free and colorimetric mercury ions detection

    International Nuclear Information System (INIS)

    Gao Shuyan; Jia Xiaoxia; Chen Yanli

    2013-01-01

    Mercury in the environment from global mercury emissions as well as various forms of contamination poses severe threats to both human health and the environment. Long-term exposure to high levels of Hg-based toxins results in serious and irreversible damage of the central nervous system and other organs. Therefore, the development of effective sensing systems for mercury detection becomes an increasing demand. In this article, a yogurt-mediated silver nanostructure is reported to be unprecedentedly used in the naked-eye and label-free detection of mercury. The method relies on the redox reaction resulting from the electrode potential difference between Ag + /Ag (0.7996 V) and Hg 2+ /Hg 2 2+ (0.920 V) that makes colorless Hg 2+ ions which oxidize colored silver nanoparticle (AgNP) to colorless Ag+. The labor-intensive modification of AgNPs and expensive labeling are avoided, and the traditional AuNPs are substituted by AgNPs in this Hg 2+ ions sensing platform, which makes it facile, low-cost, and particularly useful for home, clinic, or field applications as well as resource-limited conditions. This sensing system achieves a detection limit as low as 10 nM, lower than the toxicity level of Hg 2+ ions in drinking water (30 nM) defined by World Health Organization, and exhibits excellent selectivity, largely free from the matrix effect of the real water samples. This visual label-free Hg 2+ ions sensing motif shows great promise for sensing Hg 2+ ions in terms of sensitivity, selectivity, cost, and maneuverability. It is also a good example for the organic combination of green chemistry and functional materials, which may trigger interest in furthering biosystems for environmental science applications.

  10. Old tree with new shoots: silver nanoparticles for label-free and colorimetric mercury ions detection

    Energy Technology Data Exchange (ETDEWEB)

    Gao Shuyan, E-mail: shuyangao@htu.cn; Jia Xiaoxia; Chen Yanli [Henan Normal University, College of Chemistry and Environmental Science (China)

    2013-01-15

    Mercury in the environment from global mercury emissions as well as various forms of contamination poses severe threats to both human health and the environment. Long-term exposure to high levels of Hg-based toxins results in serious and irreversible damage of the central nervous system and other organs. Therefore, the development of effective sensing systems for mercury detection becomes an increasing demand. In this article, a yogurt-mediated silver nanostructure is reported to be unprecedentedly used in the naked-eye and label-free detection of mercury. The method relies on the redox reaction resulting from the electrode potential difference between Ag{sup +}/Ag (0.7996 V) and Hg{sup 2+}/Hg{sub 2}{sup 2+} (0.920 V) that makes colorless Hg{sup 2+} ions which oxidize colored silver nanoparticle (AgNP) to colorless Ag+. The labor-intensive modification of AgNPs and expensive labeling are avoided, and the traditional AuNPs are substituted by AgNPs in this Hg{sup 2+} ions sensing platform, which makes it facile, low-cost, and particularly useful for home, clinic, or field applications as well as resource-limited conditions. This sensing system achieves a detection limit as low as 10 nM, lower than the toxicity level of Hg{sup 2+} ions in drinking water (30 nM) defined by World Health Organization, and exhibits excellent selectivity, largely free from the matrix effect of the real water samples. This visual label-free Hg{sup 2+} ions sensing motif shows great promise for sensing Hg{sup 2+} ions in terms of sensitivity, selectivity, cost, and maneuverability. It is also a good example for the organic combination of green chemistry and functional materials, which may trigger interest in furthering biosystems for environmental science applications.

  11. Contribution of Eu ions on the precipitation of silver nanoparticles in Ag-Eu co-doped borate glasses

    International Nuclear Information System (INIS)

    Jiao, Qing; Qiu, Jianbei; Zhou, Dacheng; Xu, Xuhui

    2014-01-01

    Graphical abstract: - Highlights: • Silver nanoparticles are precipitated from the borate glasses during the melting process without any further heat treatment. • The reduction of Eu 3+ ions to Eu 2+ ions is presented in this material. • The intensity of Ag + luminescence. • The introduction of Eu ions accelerated the reaction between Eu 2+ ions and silver ions inducing the silver clusters formation. - Abstract: Ag + doped sodium borate glasses with different Eu ions concentration were prepared by the melt-quenching method. The absorption at about 410 nm which was caused by the surface plasmon resonance (SPR) of Ag nanoparticles (NPs) is promoted with increasing of Eu ions concentration. Meanwhile, the luminescent spectra showed that the emission intensity of Ag + decreased while that of the Ag aggregates increased simultaneously. The results indicated that the Ag ions intend to form the high-polymeric state such as Ag aggregates and nanoparticles with increasing of europium ions. Owing to the self-reduction of Eu 3+ to Eu 2+ in our glass system, it revealed that Ag + has been reduced by the neighboring Eu 2+ which leads to the formation of Ag aggregates and the precipitation of Ag NPs in the matrix. In addition, energy transfer (ET) process from Ag + /Ag aggregates to the Eu 3+ was investigated for the enhancement of Eu 3+ luminescence

  12. Mixed moderate thermophilic bioleaching of Cu, Mo and Re from molybdenite concentrate: effects of silver ion, medium and energy sources

    Directory of Open Access Journals (Sweden)

    Hadi Abdollahi

    2017-12-01

    Full Text Available This study evaluates the effects of different additives such as silver ion, medium and energy sources on the efficiency of mixed moderate thermophilic bioleaching approach to extract Cu, Mo and Re from molybdenite concentrate containing 0.98% Cu, 1.56% Fe, 53.84% Mo, and 0.055% Re. Molybdenite was the major phase of Mo-bearing mineral and chalcopyrite, covellite and pyrite were distinguished as minor phases. The higher copper extraction was obtained in tests with silver additives in all types and quantities rather than tests without silver ion. Kinetic of copper dissolution varied in these experiments and depended on the types and amounts of silver, and other supplemented additives such as ferric ion. There was no clear difference in the copper extraction by various culture media and 100% of Cu was dissolved after 30 days of treatment, using 50 mg/L of silver nitrate as additives. In the best condition and without silver additives, maximum 60% of copper was extracted even in the presence of energy sources such as sulfur, ferrous and ferric ions. In the most effective test with initial pH 1.57, 50 mg/L silver nitrate, and 50 g/L ferric sulfate, 100% of copper was dissolved in less than a week with highest kinetics rate. Molybdenum and rhenium extraction had the same tends with redox potential graph. By increasing the redox potential to the 550-600mV, molybdenite started to dissolve and finally, molybdenum and rhenium were extracted 2% and 9.53% in the best condition; respectively.

  13. Reduction and aggregation of silver, copper and cadmium ions in aqueous solutions of gelatin and carboxymethyl cellulose

    International Nuclear Information System (INIS)

    Kapoor, S.; Gopinathan, C.

    1998-01-01

    Radiolytic reduction of silver, copper and cadmium ions and the subsequent formation of their clusters was studied in aqueous gelatin or carboxy methyl cellulose (CMC) solutions. Presence of gelatin or CMC in the solution affects the early processes. The rate of reduction by hydrated electron reduces due to complexation. However, when the ratio of silver ions to monomeric chains decreases over a certain limit the process of reduction inhibits completely. The effect of ionic strength or pH and the reducing radical on the rate of formation of colloidal Cu and Cd is also discussed

  14. Release of mineral ions in dental plaque following acid production.

    Science.gov (United States)

    Tanaka, M; Margolis, H C

    1999-03-01

    The release of appreciable amounts of calcium, phosphate and fluoride found in whole plaque into the plaque-fluid phase, following bacterial acid production, can potentially reduce the driving force for tooth demineralization. However, limited information is available on this topic, particularly on the release of fluoride. This study sought to determine the change in calcium, phosphate and fluoride concentrations in plaque fluid after sucrose exposure. 48 h overnight-fasted supragingival plaque samples were collected from all tooth surfaces (with the exception of the lower lingual anterior teeth) of one half of an individual mouth, following a 1 min water rinse. Plaque samples were then collected from the other half of the same mouth, following a 292 mM sucrose rinse. Plaque fluid was isolated by centrifugation and analysed for total calcium and phosphate (ion chromatography) and for free fluoride (ion-specific electrode). Samples were collected from seven individuals. Following sucrose exposure, plaque-fluid pH decreased significantly from 6.5+/- 0.3 to 5.4+/-0.2; calcium concentrations (mmol/l) also increased significantly (p Fluoride and phosphate concentrations in plaque fluid, however, did not increase significantly after sucrose exposure: mean concentrations (mmol/l) of fluoride after the water and sucrose rinses were 0.006+/-0.003 and 0.005+/-0.002, respectively, and mean phosphate concentrations (mmol/l) were 11.0+/-2.0 and 12.0+/-3.0, respectively. When results were expressed per wet plaque weight, phosphate concentrations were also found to increase significantly. The same trends were observed when additional plaque samples were treated in vitro with sucrose: fluoride-ion activity did not increase in plaque under in vivo-like conditions.

  15. Selective adsorption of silver(I) ions over copper(II) ions on a sulfoethyl derivative of chitosan.

    Science.gov (United States)

    Petrova, Yulia S; Pestov, Alexandr V; Usoltseva, Maria K; Neudachina, Ludmila K

    2015-12-15

    This study presents a simple and effective method of preparation of N-(2-sulfoethyl) chitosan (NSE-chitosan) that allows obtaining a product with a degree of modification up to 1.0. The chemical structure of the obtained polymers was confirmed by FT-IR and 1H NMR spectroscopies. Cross-linking of N-(2-sulfoethyl) chitosans by glutaraldehyde allows preparation of sorbents for removal and concentration of metal ions. Capacity of sorbents towards hydroxide ions was determined depending on the degree of sulfoethylation under static and dynamic conditions. Dissociation constants of functional amino groups of the analyzed sorbents were determined by potentiometric titration. It was shown that basicity of the amino groups decreased (wherein pKa decreased from 6.53 to 5.67) with increase in degree of sulfoethylation. It explains the significant influence of sulfo groups on selectivity of sorption of metal ions on N-(2-sulfoethyl) chitosan-based sorbents. The investigated substances selectively remove copper(II) and silver(I) ions from solutions of complex composition. Wherein the selectivity coefficient KAg/Cu increased to 20 (pH 6.5, ammonium acetate buffer solution) with increase in degree of sulfoethylation of the sorbent up to 1.0. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Ultrastructural analysis of nanoparticles and ions released in periprosthetic membranes.

    Science.gov (United States)

    Sabbatini, Maurizio; Gatti, Giorgio; Renò, Filippo; Bosetti, Michela; Marchese, Leonardo; Cannas, Mario

    2014-12-30

    The distribution and relationship of hydroxyapatite debris, nanometric organic and metal wear particles and metal ions on periimplant interface membranes following aseptic and septic arthroplastic loosening were investigated. Scanning electron microscopy and X-ray spectroscopic analysis were used to analyze debris and ion distribution. Hydroxyapatite debris appeared with different morphology in a particular distribution among several membranes. These differences may reflect the occurrence of different friction forces taking place between prosthesis and bone interface in the several types of prostheses studied. Metal wear particles were detected in greater numbers in membranes from noncemented prostheses compared with those from cemented ones. In contrast, more organic particles were present in membrane from cemented prosthesis. No differences were observed between aseptic and septic membranes. Our findings support the need to evaluate the occurrence of friction forces that periprosthetic bone debris production may induce to exacerbate cellular reactivity. Furthermore, cellular engulfment of debris and the high level of different ions released indicate the occurrence of a toxic environment that may induce failure of any reparative pathways.

  17. Orthodontic cement with protein-repellent and antibacterial properties and the release of calcium and phosphate ions.

    Science.gov (United States)

    Zhang, Ning; Weir, Michael D; Chen, Chen; Melo, Mary A S; Bai, Yuxing; Xu, Hockin H K

    2016-07-01

    White spot lesions often occur in orthodontic treatments. The objective of this study was to develop a novel resin-modified glass ionomer cement (RMGI) as an orthodontic cement with protein-repellent, antibacterial and remineralization capabilities. Protein-repellent 2-methacryloyloxyethyl phosphorylcholine (MPC), antibacterial dimethylaminohexadecyl methacrylate (DMAHDM), nanoparticles of silver (NAg), and nanoparticles of amorphous calcium phosphate (NACP) were incorporated into a RMGI. Enamel shear bond strength (SBS) was determined. Calcium (Ca) and phosphate (P) ion releases were measured. Protein adsorption onto specimens was determined by a micro bicinchoninic acid method. A dental plaque microcosm biofilm model was tested. Increasing the NACP filler level increased the Ca and P ion release. Decreasing the solution pH increased the ion release. Incorporating MPC into RMGI reduced protein adsorption, which was an order of magnitude less than that of commercial controls. Adding DMAHDM and NAg into RMGI yielded a strong antibacterial function, greatly reducing biofilm viability and acid production. Biofilm CFU counts on the multifunctional orthodontic cement were 3 orders of magnitude less than that of commercial control (p0.1). A novel multifunctional orthodontic cement was developed with strong antibacterial and protein-repellent capabilities for preventing enamel demineralization. The new cement is promising to prevent white spot lesions in orthodontic treatments. The method of incorporating four bioactive agents may have wide applicability to the development of other bioactive dental materials to inhibit caries. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Biomineralization of hydroxyapatite in silver ion-exchanged nanocrystalline ZSM-5 zeolite using simulated body fluid.

    Science.gov (United States)

    Kaur, Balwinder; Srivastava, Rajendra; Satpati, Biswarup; Kondepudi, Kanthi Kiran; Bishnoi, Mahendra

    2015-11-01

    Silver ion-exchanged nanocrystalline zeolite (Ag-Nano-ZSM-5) and silver ion-exchanged conventional zeolite (Ag-ZSM-5) were synthesized. Zeolites were incubated in simulated body fluid at 310K for different time periods to grow hydroxyapatite in their matrixes. Significant large amount of hydroxyapatite was grown in Ag-Nano-ZSM-5 matrix after incubation in simulated body fluid when compared to Ag-ZSM-5. The resultant material was characterized using X-ray diffraction, N2-adsorption, scanning/transmission electron microscopy, energy dispersive X-ray, and inductively coupled plasma analysis. Mechanical properties such as compressive modulus, compressive strength, and strain at failure of the parent materials were evaluated. Biocompatibility assays suggested that Ag-Nano-ZSM-5 and hydroxyapatite grown in Ag-Nano-ZSM-5 were compatible and did not impose any toxicity to RAW 264.7 cells macrophase and Caco2 cells suggesting considerable potential for biomedical applications such as bone implants. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Schiff Base modified on CPE electrode and PCB gold electrode for selective determination of silver ion

    Science.gov (United States)

    Leepheng, Piyawan; Suramitr, Songwut; Phromyothin, Darinee

    2017-09-01

    The schiff base was synthesized by 2,5-thiophenedicarboxaldehyde and 1,2,4-thiadiazole-3,5-diamine with condensation method. There was modified on carbon paste electrode (CPE) and Printed circuit board (PCB) gold electrode for determination silver ion. The schiff base modified electrodes was characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM), respectively. The electrochemical study was reported by cyclic voltammetry method and impedance spectroscopy using modified electrode as working electrode, platinum wire and Ag/AgCl as counter electrode and reference electrode, respectively. The modified electrodes have suitable detection for Ag+. The determination of silver ions using the modified electrodes depended linearly on Ag+ concentration in the range 1×10-10 M to 1×10-7 M, with cyclic voltammetry sensitivity were 2.51×108 μAM-1 and 1.88×108 μAM-1 for PCB gold electrode and CPE electrode, respectively, limits of detection were 5.33×10-9 M and 1.99×10-8 M for PCB gold electrode and CPE electrode, respectively. The modified electrodes have high accuracy, inexpensive and can applied to detection Ag+ in real samples.

  20. Silver-coated ion exchange membrane electrode applied to electrochemical reduction of carbon dioxide

    International Nuclear Information System (INIS)

    Hori, Y.; Ito, H.; Okano, K.; Nagasu, K.; Sato, S.

    2003-01-01

    Silver-coated ion exchange membrane electrodes (solid polymer electrolyte, SPE) were prepared by electroless deposition of silver onto ion exchange membranes. The SPE electrodes were used for carbon dioxide (CO 2 ) reduction with 0.2 M K 2 SO 4 as the electrolyte with a platinum plate (Pt) for the counterelectrode. In an SPE electrode system prepared from a cation exchange membrane (CEM), the surface of the SPE was partly ruptured during CO 2 reduction, and the reaction was rapidly suppressed. SPE electrodes made of an anion exchange membrane (SPE/AEM) sustained reduction of CO 2 to CO for more than 2 h, whereas, the electrode potential shifted negatively during the electrolysis. The reaction is controlled by the diffusion of CO 2 through the metal layer of the SPE electrode at high current density. Ultrasonic radiation, applied to the preparation of SPE/AEM, was effective to improve the electrode properties, enhancing the electrolysis current of CO 2 reduction. Observation by a scanning electron microscope (SEM) showed that the electrode metal layer became more porous by the ultrasonic radiation treatment. The partial current density of CO 2 reduction by SPE/AEM amounted to 60 mA cm -2 , i.e. three times the upper limit of the conventional electrolysis by a plate electrode. Application of SPE device may contribute to an advancement of CO 2 fixation at ambient temperature and pressure

  1. Anodic stripping voltammetric determination of silver ion at a carbon paste electrode modified with carbon nanotubes

    International Nuclear Information System (INIS)

    Tashkhourian, J.; Javadi, S.; Ana, F.N.

    2011-01-01

    A carbon paste electrode (CPE) was modified with multi-wall carbon nanotubes and successfully applied to the determination of silver ion by differential pulse anodic stripping voltammetry. Compared to a conventional CPE, a remarkably improved peak current response and sensitivity is observed. The analytical procedure consisted of an open circuit accumulation step for 2 min in -0.4 V, this followed by an anodic potential scan between +0.2 and + 0.6 V to obtain the voltammetric peak. The oxidation peak current is proportional to the concentration of silver ion in the range from 1.0 x 10 -8 to 1.0 x 10 -5 mol L -1 , with a detection limit of 1.8 x 10 -9 mol L -1 after an accumulation time of 120 s. The relative standard deviation for 7 successive determinations of Ag(I) at 0.1 μM concentration is 1.99%. The procedure was validated by determining Ag(I) in natural waters. (author)

  2. Silver ions-mediated conformational switch: facile design of structure-controllable nucleic acid probes.

    Science.gov (United States)

    Wang, Yongxiang; Li, Jishan; Wang, Hao; Jin, Jianyu; Liu, Jinhua; Wang, Kemin; Tan, Weihong; Yang, Ronghua

    2010-08-01

    Conformationally constraint nucleic acid probes were usually designed by forming an intramolecular duplex based on Watson-Crick hydrogen bonds. The disadvantages of these approaches are the inflexibility and instability in complex environment of the Watson-Crick-based duplex. We report that this hydrogen bonding pattern can be replaced by metal-ligation between specific metal ions and the natural bases. To demonstrate the feasibility of this principle, two linear oligonucleotides and silver ions were examined as models for DNA hybridization assay and adenosine triphosphate detection. The both nucleic acids contain target binding sequences in the middle and cytosine (C)-rich sequences at the lateral portions. The strong interaction between Ag(+) ions and cytosines forms stable C-Ag(+)-C structures, which promises the oligonucleotides to form conformationally constraint formations. In the presence of its target, interaction between the loop sequences and the target unfolds the C-Ag(+)-C structures, and the corresponding probes unfolding can be detected by a change in their fluorescence emission. We discuss the thermodynamic and kinetic opportunities that are provided by using Ag(+) ion complexes instead of traditional Watson-Crick-based duplex. In particular, the intrinsic feature of the metal-ligation motif facilitates the design of functional nucleic acids probes by independently varying the concentration of Ag(+) ions in the medium.

  3. Chitosan-stabilized Silver Nanoparticles for Colorimetric Assay of Mercury (II) Ions in aqueous system

    Science.gov (United States)

    Zarlaida, Fitri; Adlim, M.; Syukri Surbakti, M.; Fairuz Omar, Ahmad

    2018-05-01

    Mercury is considered as dangerous pollutant. Among the many form of mercury, the most stable and soluble in water is mercury (II) ions which it cause threat to human health and surroundings. Silver nanoparticles (AgNPs) used in this method were prepared by chitosan (chi) which act as stabilizing agent. The Chi-AgNPs has good dispersity with size ranging from 2.50 to 6.00 nm as shown by transmission electron microscopy (TEM) analysis and it is stable for 3 months. Color of Chi-AgNPs fades from brownish-yellow to colorless only with Hg2+ ions, but it shows no significant changes upon addition of other metal ions such as Al3+, Ba2+, Ca2+, Cd2+, Cr3+, Co2+, Cu2+, Fe2+, K+, Mg2+, Mn2+, Na+, Ni2+, Pb2+, and Zn2+. The detection limit for Hg2+ ions by bare-eye is estimated to be ∼1µM. This method can be used for sensing mercury(II) ions in numerous water samples.

  4. Determination of Silver Ions Toxicity in Short-Term and Long-Term Experiments Using a Luminescent Recombinant Strain of E. coli

    Directory of Open Access Journals (Sweden)

    Tatiana P. Yudina

    2013-01-01

    Full Text Available The effects of silver ions on the luminescent recombinant strain of Escherichia coli carrying luxCDABE operon of Vibrio fischeri were investigated. The toxicity of silver ions was determined in 30 minutes and in chronic 24 hours experiments. Changes in the luminescence intensity and in the growth rate of bacteria were considered as a measure of silver ions toxicity within the range of concentrations applied. The effect of silver ions was demonstrated to be strongly dependent on the concentration of bacteria and on the medium composition. EC50 values were 0.018 mg/l after 30 min exposure and 0.014 mg/l after 10 hours of bacterial growth. Comparison of two modifications of the experiment showed that silver ions have a strong non-specific toxicity, as well as a specific effect on bacterial cells

  5. In situ reduction of antibacterial silver ions to metallic silver nanoparticles on bioactive glasses functionalized with polyphenols

    Energy Technology Data Exchange (ETDEWEB)

    Ferraris, S., E-mail: sara.ferraris@polito.it [Department of Applied Science and Technology, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129, Torino (Italy); Miola, M. [Department of Applied Science and Technology, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129, Torino (Italy); Department of Health Sciences, Università del Piemonte Orientale UPO, Via Solaroli 17, 28100, Novara (Italy); Cochis, A.; Azzimonti, B.; Rimondini, L. [Department of Health Sciences, Università del Piemonte Orientale UPO, Via Solaroli 17, 28100, Novara (Italy); Prenesti, E. [Department of Chemistry, Università degli Studi di Torino, Via Pietro Giuria 7, Torino, 10125 (Italy); Vernè, E. [Department of Applied Science and Technology, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129, Torino (Italy)

    2017-02-28

    Highlights: • Gallic acid and natural polyphenols were grafted onto bioactive glasses. • Grafting ability was dependent on glass reactivity. • In situ reduction of silver nanoparticles was performed onto functionalized glasses. • Bioactive glasses decorated with silver nanoparticles showed antibacterial activity. - Abstract: The realization of surfaces with antibacterial properties due to silver nanoparticles loaded through a green approach is a promising research challenge of the biomaterial field. In this research work, two bioactive glasses have been doubly surface functionalized with polyphenols (gallic acid or natural polyphenols extracted from red grape skins and green tea leaves) and silver nanoparticles deposited by in situ reduction from a silver nitrate aqueous solution. The presence of biomolecules – showing reducing ability to directly obtain in situ metallic silver – and silver nanoparticles was investigated by means of UV–vis spectroscopy, X-Ray Photoelectron Spectroscopy (XPS) and Field Emission Scanning Electron Microscopy (FESEM). The antibacterial activity of the modified surfaces was tested against a multidrug resistant Staphylococcus aureus bacterial strain.

  6. Toxicological Assessment of a Lignin Core Nanoparticle Doped with Silver as an Alternative to Conventional Silver Core Nanoparticles

    Directory of Open Access Journals (Sweden)

    Cassandra E. Nix

    2018-05-01

    Full Text Available Elevated levels of silver in the environment are anticipated with an increase in silver nanoparticle (AgNP production and use in consumer products. To potentially reduce the burden of silver ion release from conventional solid core AgNPs, a lignin-core particle doped with silver ions and surface-stabilized with a polycationic electrolyte layer was engineered. Our objective was to determine whether any of the formulation components elicit toxicological responses using embryonic zebrafish. Ionic silver and free surface stabilizer were the most toxic constituents, although when associated separately or together with the lignin core particles, the toxicity of the formulations decreased significantly. The overall toxicity of lignin formulations containing silver was similar to other studies on a silver mass basis, and led to a significantly higher prevalence of uninflated swim bladder and yolk sac edema. Comparative analysis of dialyzed samples which had leached their loosely bound Ag+, showed a significant increase in mortality immediately after dialysis, in addition to eliciting significant increases in types of sublethal responses relative to the freshly prepared non-dialyzed samples. ICP-OES/MS analysis indicated that silver ion release from the particle into solution was continuous, and the rate of release differed when the surface stabilizer was not present. Overall, our study indicates that the lignin core is an effective alternative to conventional solid core AgNPs for potentially reducing the burden of silver released into the environment from a variety of consumer products.

  7. Separation, preconcentration and determination of silver ion from water samples using silica gel modified with 2,4,6-trimorpholino-1,3,5-triazin

    International Nuclear Information System (INIS)

    Madrakian, Tayyebeh; Afkhami, Abbas; Zolfigol, Mohammad Ali; Solgi, Mohammad

    2006-01-01

    A new modified silica gel using 2,4,6-trimorpholino-1,3,5-triazin was used for separation, preconcentration and determination of silver ion in natural water by atomic absorption spectrometry (AAS). This new bonded silica gel was used as an effective sorbent for the solid-phase extraction (SPE) of silver ion from aqueous solutions. Experimental conditions for effective adsorption of trace levels of silver ion were optimized with respect to different experimental parameters in column process. Common coexisting ions did not interfere with the separation and determination of silver at pH 3.5 so that silver ion completely adsorbed on the column. The preconcentration factor is 130 (1 mL elution volume for a 130 mL sample volume). The relative standard deviation (R.S.D.) under optimum conditions is 3.03% (n = 5). The accuracy of the method was estimated by using spring and tap water samples that were spiked with different amounts of silver ion. The adsorption isotherm of silver ion was obtained. The capacity of the sorbent at optimum conditions has been found to be 384 μg of silver per gram of sorbent

  8. Silver ion chromatography for peak resolution enhancement: Application to the preparative separation of two sesquiterpenes using online heart-cutting LC-LC technique.

    Science.gov (United States)

    Yang, Yang; Zhang, Yongmin; Wei, Chong; Li, Jing; Sun, Wenji

    2018-09-01

    Silver ion chromatography, utilizing columns packed with silver ions bonded to silica gel, has proved to be an invaluable technique for the analysis of some positional isomers. In this work, silver ion chromatography by combination with online heart-cutting LC-LC technique for the preparative separation of two sesquiterpenes positional isomers from a natural product was investigated. On the basis of the evaluation that silver ion content impacts on the separation, the laboratory-made silver ion columns, utilizing silica gel impregnated with 15% silver nitrate as column packing materials, were used for peak resolution improvement of these two isomers and the preparative separation of them in heart-cutting LC-LC. The relationship among the maximal sample load, flow rate and peak resolution in the silver ion column were optimized, and the performance of the silver ion column was compared with conventional C 18 column and silica gel column. Based on the developed chromatographic conditions, online heart-cutting LC-LC chromatographic separation system in combination with a silica gel column and a silver ion column that was applied to preparative separation of these two isomers from a traditional Chinese medicine, Inula racemosa Hook.f., was established. The results showed that the online heart-cutting LC-LC technique by combination of a silica gel column and a silver ion column for the preparative separation of these two positional isomers from this natural plant was superior to the preparative separation performed on a single-column system with C 18 column or silica gel column. Copyright © 2018 Elsevier B.V. All rights reserved.

  9. Ion beam assisted synthesis of nano-crystals in glasses (silver and lead chalcogenides)

    International Nuclear Information System (INIS)

    Espiau de Lamaestre, R.

    2005-04-01

    This work deals with the interest in ion beams for controlling nano-crystals synthesis in glasses. We show two different ways to reach this aim, insisting on importance of redox phenomena induced by the penetration and implantation of ions in glasses. We first show that we can use the great energy density deposited by the ions to tailor reducing conditions, favorable to metallic nano-crystal precipitation. In particular, we show that microscopic mechanism of radiation induced silver precipitation in glasses are analogous to the ones of classical photography. Ion beams can also be used to overcome supersaturation of elements in a given matrix. In this work, we synthesized lead chalcogenide nano-crystals (PbS, PbSe, PbTe) whose optical properties are interesting for telecommunication applications. We demonstrate the influence of complex chalcogenide chemistry in oxide glasses, and its relationship with the observed loss of growth control when nano-crystals are synthesized by sequential implantation of Pb and S in pure silica. As a consequence of this understanding, we demonstrate a novel and controlled synthesis of PbS nano-crystals, consisting in implanting sulfur into a Pb-containing glass, before annealing. Choice of glass composition provides a better control of precipitation physico-chemistry, whereas the use of implantation allows high nano-crystal volume fractions to be reached. Our study of IR emission properties of these nano-crystals shows a very high excitation cross section, and evidence for a 'dark exciton' emitting level. (author)

  10. Fluorescent carbon quantum dot hydrogels for direct determination of silver ions.

    Science.gov (United States)

    Cayuela, A; Soriano, M L; Kennedy, S R; Steed, J W; Valcárcel, M

    2016-05-01

    The paper reports for the first time the direct determination of silver ion (Ag(+)) using luminescent Carbon Quantum Dot hydrogels (CQDGs). Carbon Quantum Dots (CQDs) with different superficial moieties (passivate-CQDs with carboxylic groups, thiol-CQDs and amine-CQDs) were used to prepare hybrid gels using a low molecular weight hydrogelator (LMWG). The use of the gels results in considerable fluorescence enhancement and also markedly influences selectivity. The most selective CQDG system for Ag(+) ion detection proved to be those containing carboxylic groups onto their surface. The selectivity towards Ag(+) ions is possibly due to its flexible coordination sphere compared with other metal ions. This fluorescent sensing platform is based on the strong Ag-O interaction which can quench the photoluminescence of passivate-CQDs (p-CQDs) through charge transfer. The limit of detection (LOD) and quantification (LOQ) of the proposed method were 0.55 and 1.83µgmL(-1), respectively, being applied in river water samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Colorimetric determination of copper ions based on the catalytic leaching of silver from the shell of silver-coated gold nanorods

    International Nuclear Information System (INIS)

    Wang, Xiaokun; Chen, Lingxin; Chen, Ling

    2014-01-01

    We have developed a method for the colorimetric determination of copper ions (Cu 2+ ) that is based on the use of silver-coated gold nanorods (Au–Ag NRs). Its outstanding selectivity and sensitivity result from the catalytic leaching process that occurs between Cu 2+ , thiosulfate (S 2 O 3 2− ), and the surface of the Au–Ag NRs. The intrinsic color of the Au–Ag NRs changes from bright red to bluish green with decreasing thickness of the silver coating. The addition of Cu 2+ accelerates the leaching of silver from the shell caused in the presence of S 2 O 3 2− . This result in a decrease in the thickness of the silver shell which is accompanied a change in color and absorption spectra of the colloidal solution. The shifts in the absorption maxima are linearly related to the concentrations of Cu 2+ over the 3–1,000 nM concentration range (R = 0.996). The method is cost effective and was applied to the determination of Cu 2+ in real water samples. (author)

  12. The antimicrobial activity of as-prepared silver-loaded phosphate glasses and zirconium phosphate

    International Nuclear Information System (INIS)

    Jing, Wang; Jiang, Ji Zhi; Yang, Yang; Yan, Zhao Chun; Yan, Wang Xiao; He, Shui Zhong

    2016-01-01

    The antimicrobial activities of silver-loaded zirconium phosphate (JDG) and silver-loaded phosphate glasses (ZZB) against Escherichia coli were studied. Although the silver content in JDG was higher than that in ZZB, ZZB suspensions showed better antimicrobial property than JDG suspensions, especially at low concentrations. The antimicrobial activity was analyzed using minimum inhibitory concentrations, bacterial inhibition ring tests, and detection of silver ions in the suspensions. Furthermore, the amounts of silver ions in suspensions with/without bacterial cells were analyzed. Results revealed that only a portion of released silver ions could be adsorbed by E. coli cells, which are critical to cell death. The damaged microstructures of E. coli cells observed by transmission electron microscopy may further prove that the adsorbed silver ions play an important role in the antimicrobial process.

  13. Angiogenesis in calcium phosphate scaffolds by inorganic copper ion release.

    Science.gov (United States)

    Barralet, Jake; Gbureck, Uwe; Habibovic, Pamela; Vorndran, Elke; Gerard, Catherine; Doillon, Charles J

    2009-07-01

    Angiogenesis in a tissue-engineered device may be induced by incorporating growth factors (e.g., vascular endothelial growth factor [VEGF]), genetically modified cells, and=or vascular cells. It represents an important process during the formation and repair of tissue and is essential for nourishment and supply of reparative and immunological cells. Inorganic angiogenic factors, such as copper ions, are therefore of interest in the fields of regenerative medicine and tissue engineering due to their low cost, higher stability, and potentially greater safety compared with recombinant proteins or genetic engineering approaches. The purpose of this study was to compare tissue responses to 3D printed macroporous bioceramic scaffolds implanted in mice that had been loaded with either VEGF or copper sulfate. These factors were spatially localized at the end of a single macropore some 7 mm from the surface of the scaffold. Controls without angiogenic factors exhibited only poor tissue growth within the blocks; in contrast, low doses of copper sulfate led to the formation of microvessels oriented along the macropore axis. Further, wound tissue ingrowth was particularly sensitive to the quantity of copper sulfate and was enhanced at specific concentrations or in combination with VEGF. The potential to accelerate and guide angiogenesis and wound healing by copper ion release without the expense of inductive protein(s) is highly attractive in the area of tissue-engineered bone and offers significant future potential in the field of regenerative biomaterials.

  14. Analysis of wax esters by silver-ion high-performance liquid chromatography-tandem mass spectrometry

    Czech Academy of Sciences Publication Activity Database

    Vrkoslav, Vladimír; Urbanová, Klára; Háková, Martina; Cvačka, Josef

    2013-01-01

    Roč. 1302, Aug 9 (2013), s. 105-110 ISSN 0021-9673 R&D Projects: GA ČR GA203/09/0139 Institutional support: RVO:61388963 Keywords : jojoba * human hair * wax esters * mass spectrometry * silver-ion liquid chromatography * long-chain esters Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 4.258, year: 2013

  15. Electrode fabrication for Lithium-ion batteries by intercalating of carbon nano tubes inside nano metric pores of silver foam

    International Nuclear Information System (INIS)

    Khoshnevisan, B.

    2011-01-01

    Here there is an on effort to improve working electrode (Ag + carbon nano tubes) preparation for Li-Ion batteries applications. Nano scaled silver foam with high specific area has been employed as a frame for loading carbon nano tubes by electrophoretic deposition method. In this ground, the prepared electrodes show a very good stability and also charge-discharge cycles reversibility.

  16. Application of the atomic absorption technical to available the concentration of silver ions incorporated in glass matrix by ionic exchange process

    International Nuclear Information System (INIS)

    Mendes, E.; Silva, K.F.; Teixeira, A.; Silva, L.; Paula, M.M.S.; Angioletto, E.; Riella, H.G.; Fiori, M. A.

    2009-01-01

    Ion specimens can be incorporated in glasses or natural clays by ionic exchange process with different concentrations dependent of matrix's type and of the ionic exchange parameters. In particular, the incorporation of silver ions presents high interest by its biocidal properties. A compound contending ion silver specimens presents bactericidal and fungicidal properties with effect proportional to ion concentration. This work presents results about application of the atomic absorption technical to determine the silver ion concentration incorporated in a glass matrix by ionic exchange process. The ionic exchange experiments were realized with different AgNO 3 concentration and constant temperature. After ionic exchange process, the glass samples were submitted to characterization by Energy Dispersive X-Ray Spectroscopy and Atomic Absorption Techniques. The comparative results between different techniques showed that atomic absorption technical is adequate to determine ion silver concentration incorporated in the glass matrix after ionic exchange process. (author)

  17. Different routes, same pathways: Molecular mechanisms under silver ion and nanoparticle exposures in the soil sentinel Eisenia fetida

    International Nuclear Information System (INIS)

    Novo, Marta; Lahive, Elma; Díez-Ortiz, María; Matzke, Marianne; Morgan, Andrew J.; Spurgeon, David J.; Svendsen, Claus; Kille, Peter

    2015-01-01

    Use of nanotechnology products is increasing; with silver (Ag) nanoparticles particularly widely used. A key uncertainty surrounding the risk assessment of AgNPs is whether their effects are driven through the same mechanism of action that underlies the toxic effects of Ag ions. We present the first full transcriptome study of the effects of Ag ions and NPs in an ecotoxicological model soil invertebrate, the earthworm Eisenia fetida. Gene expression analyses indicated similar mechanisms for both silver forms with toxicity being exerted through pathways related to ribosome function, sugar and protein metabolism, molecular stress, disruption of energy production and histones. The main difference seen between Ag ions and NPs was associated with potential toxicokinetic effects related to cellular internalisation and communication, with pathways related to endocytosis and cilia being significantly enriched. These results point to a common final toxicodynamic response, but initial internalisation driven by different exposure routes and toxicokinetic mechanisms. - Highlights: • Molecular effects underlying Ag ions and NPs exposure were studied in Eisenia fetida. • Full transcriptomic study of a genetically characterised lineage. • NPs and ions presented a similar toxicodynamic response. • Internalisation of the two Ag forms by different toxicokinetic mechanisms. - Transcriptomic analyses after exposure of earthworms to silver NPs or ions showed a final common toxicodynamic response, but internalisation by different toxicokinetic mechanisms

  18. AFM and XRD characterization of silver nanoparticles films deposited on the surface of DGEBA epoxy resin by ion sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Jose Elisandro de; Machado, Rogerio; Macedo, Marcelo Andrade; Cunha, Frederico Guilherme Carvalho [Clinica de Medicina Nuclear e Radiologia de Maceio (MedRadiUS), Radiology and Imaging Diagnosis at Universidade Federal de Alagoas (UFAL), Maceio, AL (Brazil)

    2012-07-01

    In this work, silver atoms were deposited by ion sputtering on the surface of diglycidyl ether of bisphenol A (DGEBA) epoxy resin cured at 150 deg C for 6 hours in air. The films of DGEBA and its precursors were characterized by Raman spectroscopy to identify the main functional groups and their relationship with the deposited silver atoms. Silver thin films of 5, 10, 15 and 20 nm were deposited on the epoxy resin at room temperature. Both the initial film of DGEBA and the subsequent silver thin film were analyzed by Atomic Force Microscopy (AFM) in the non-contact mode. Silver thin films were also analyzed using X-ray diffraction (XRD) at room temperature. The AFM results showed the formation of silver crystallites on the surface of DGEBA at very low coverage whereas XRD indicated that most of them had their main axis aligned to the normal of the surface. An increase in the coverage led to an increase in the grain size as indicated by AFM. However, XRD results indicated that the crystallite size remained almost constant while the appearance of peaks corresponding to other crystalline orientations suggests the coalescence of the original crystallites and an increase in size of the more dense planes, namely [111]. (author)

  19. AFM and XRD characterization of silver nanoparticles films deposited on the surface of DGEBA epoxy resin by ion sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Jose Elisandro de; Machado, Rogerio; Macedo, Marcelo Andrade [Universidade Federal de Sergipe (UFSE), Aracaju, SE (Brazil). Programa de Pos-graduacao em Fisica; Cunha, Frederico Guilherme Carvalho [Universidade Federal de Sergipe (UFSE), Aracaju, SE (Brazil). Programa de Pos-graduacao em Ciencia e Engenharia de Materiais

    2012-07-01

    In this work, silver atoms were deposited by ion sputtering on the surface of diglycidyl ether of bisphenol A (DGEBA) epoxy resin cured at 150 Degree-Sign C for 6 hours in air. The films of DGEBA and its precursors were characterized by Raman spectroscopy to identify the main functional groups and their relationship with the deposited silver atoms. Silver thin films of 5, 10, 15 and 20 nm were deposited on the epoxy resin at room temperature. Both the initial film of DGEBA and the subsequent silver thin film were analyzed by Atomic Force Microscopy (AFM) in the non-contact mode. Silver thin films were also analyzed using X-ray diffraction (XRD) at room temperature. The AFM results showed the formation of silver crystallites on the surface of DGEBA at very low coverage whereas XRD indicated that most of them had their main axis aligned to the normal of the surface. An increase in the coverage led to an increase in the grain size as indicated by AFM. However, XRD results indicated that the crystallite size remained almost constant while the appearance of peaks corresponding to other crystalline orientations suggests the coalescence of the original crystallites and an increase in size of the more dense planes, namely [111]. (author)

  20. AFM and XRD characterization of silver nanoparticles films deposited on the surface of DGEBA epoxy resin by ion sputtering

    Directory of Open Access Journals (Sweden)

    José Elisandro de Andrade

    2013-01-01

    Full Text Available In this work, silver atoms were deposited by ion sputtering on the surface of diglycidyl ether of bisphenol A (DGEBA epoxy resin cured at 150 °C for 6 hours in air. The films of DGEBA and its precursors were characterized by Raman spectroscopy to identify the main functional groups and their relationship with the deposited silver atoms. Silver thin films of 5, 10, 15 and 20 nm were deposited on the epoxy resin at room temperature. Both the initial film of DGEBA and the subsequent silver thin film were analyzed by Atomic Force Microscopy (AFM in the non-contact mode. Silver thin films were also analyzed using X-ray diffraction (XRD at room temperature. The AFM results showed the formation of silver crystallites on the surface of DGEBA at very low coverage whereas XRD indicated that most of them had their main axis aligned to the normal of the surface. An increase in the coverage led to an increase in the grain size as indicated by AFM. However, XRD results indicated that the crystallite size remained almost constant while the appearance of peaks corresponding to other crystalline orientations suggests the coalescence of the original crystallites and an increase in size of the more dense planes, namely [111].

  1. A silver ion-doped calcium phosphate-based ceramic nanopowder-coated prosthesis increased infection resistance.

    Science.gov (United States)

    Kose, Nusret; Otuzbir, Ali; Pekşen, Ceren; Kiremitçi, Abdurrahman; Doğan, Aydin

    2013-08-01

    Despite progress in surgical techniques, 1% to 2% of joint arthroplasties become complicated by infection. Coating implant surfaces with antimicrobial agents have been attempted to prevent initial bacterial adhesion to implants with varying success rates. We developed a silver ion-containing calcium phosphate-based ceramic nanopowder coating to provide antibacterial activity for orthopaedic implants. We asked whether titanium prostheses coated with this nanopowder would show resistance to bacterial colonization as compared with uncoated prostheses. We inserted titanium implants (uncoated [n = 9], hydroxyapatite-coated [n = 9], silver-coated [n = 9]) simulating knee prostheses into 27 rabbits' knees. Before implantation, 5 × 10(2) colony-forming units of Staphylococcus aureus were inoculated into the femoral canal. Radiology, microbiology, and histology findings were quantified at Week 6 to define the infection, microbiologically by increased rate of implant colonization/positive cultures, histologically by leukocyte infiltration, necrosis, foreign-body granuloma, and devitalized bone, and radiographically by periosteal reaction, osteolysis, or sequestrum formation. Swab samples taken from medullary canals and implants revealed a lower proportion of positive culture in silver-coated implants (one of nine) than in uncoated (eight of nine) or hydroxyapatite-coated (five of nine) implants. Silver-coated implants also had a lower rate of colonization. No cellular inflammation or foreign-body granuloma was observed around the silver-coated prostheses. Silver ion-doped ceramic nanopowder coating of titanium implants led to an increase in resistance to bacterial colonization compared to uncoated implants. Silver-coated orthopaedic implants may be useful for resistance to local infection but will require in vivo confirmation.

  2. Swimming depth of migrating silver eels Anguilla japonica released at seamounts of the West Mariana Ridge, their estimated spawning sites

    OpenAIRE

    Aoyama, J.; Hissmann, Karen; Yoshinaga, T.; Sasai, S.; Uto, T.; Ueda, H.

    1999-01-01

    Five hormone-treated female Japanese silver eels Anguilla japonica were tagged with ultrasonic transmitters and released by submersible in the West Pacific at seamounts of the West Mariana Ridge, their supposed spawning grounds. Four eels were tracked for 60 to 423 min in the vicinity of the seamounts. They did not settle at the seamounts but swam at a mean speed of 0.37 m s-1 into open water above deep ground. Their mean swimming depth ranged from 81 to 172 m. Experiments suggest that pre-ma...

  3. 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.

  4. Study of clean and ion bombardment damaged silver single crystal surfaces by work function measurements

    International Nuclear Information System (INIS)

    Chelvayohan, N.

    1982-06-01

    Work function values of the (110), (100) and (111) faces of silver single crystal were measured by the photoelectric emission method and found to be 4.14 +- 0.04 eV, 4.22 +-0.04 eV and 4.46 +- 0.02 eV respectively. Oxygen adsorption on the faces were studied by surface potential measurement. Strong oxygen adsorption was observed on (110) and (100) faces, whereas the (111) face was found to be inert for oxygen adsorption. Oxygen adsorption on the (111) face damaged by argon ion bombardment was also investigated. The above results were compared with those of early reported work function and oxygen adsorption values. (U.K.)

  5. Synthesis of silver nanoparticles using Matricaria recutita (Babunah plant extract and its study as mercury ions sensor

    Directory of Open Access Journals (Sweden)

    Imran Uddin

    2017-11-01

    Full Text Available Silver (Ag nanoparticles comprise a highly selective approach for development of nanosensors for the detection of Hg2+ ions. When Ag nanoparticles mixes with Hg2+ ions, loses its UV–Vis absorption intensity. Here, green synthesis of Ag nanoparticles was done using plant extract of Matricaria recutita (Babunah under ambient conditions. Biosynthesized Ag nanoparticles are well-dispersed having quasi-spherical shape and average particle size of 11nm. XRD, SAED and HRTEM analysis showed that nanoparticles are well crystalline in nature and having cubic phase of geometry. We report here highly selective colorimetric detection of mercury ions (Hg2+ using biosynthesized Ag nanoparticles. Keywords: Herbal extract, Nanosensor, Biosynthesis, Matricaria recutita, Silver nanoparticles

  6. Time-resolved and integrated angular distributions of plume ions from silver at low and medium laser fluence

    DEFF Research Database (Denmark)

    Christensen, Bo Toftmann; Schou, Jørgen

    2013-01-01

    Laser impact on metals in the UV regime results in a significant number of ablated plume ions even at moderate fluence (0.7–2.4 J/cm2). The ablated particles are largely neutrals at the lowest fluence, but the fraction of ions increases strongly with fluence. The ion flow in different directions...... from a silver target irradiated by a laser beam at a wavelength of 355 nm in vacuum was measured with a hemispherical array of Langmuir probes. The time-of-flight spectra in all directions, as well as the total angular yield were determined. The angular distribution peaks strongly in forward direction...

  7. Humidity effect on nanoscale electrochemistry in solid silver ion conductors and the dual nature of its locality.

    Science.gov (United States)

    Yang, Sang Mo; Strelcov, Evgheni; Paranthaman, M Parans; Tselev, Alexander; Noh, Tae Won; Kalinin, Sergei V

    2015-02-11

    Scanning probe microscopy (SPM) is a powerful tool to investigate electrochemistry in nanoscale volumes. While most SPM-based studies have focused on reactions at the tip-surface junction, charge and mass conservation requires coupled and intrinsically nonlocal cathodic and anodic processes that can be significantly affected by ambient humidity. Here, we explore the role of water in both cathodic and anodic processes, associated charge transport, and topographic volume changes depending on the polarity of tip bias. The first-order reversal curve current-voltage technique combined with simultaneous detection of the sample topography, referred to as FORC-IVz, was applied to a silver solid ion conductor. We found that the protons generated from water affect silver ionic conduction, silver particle formation and dissolution, and mechanical integrity of the material. This work highlights the dual nature (simultaneously local and nonlocal) of electrochemical SPM studies, which should be considered for comprehensive understanding of nanoscale electrochemistry.

  8. Release of major ions during rigor mortis development in kid Longissimus dorsi muscle.

    Science.gov (United States)

    Feidt, C; Brun-Bellut, J

    1999-01-01

    Ionic strength plays an important role in post mortem muscle changes. Its increase is due to ion release during the development of rigor mortis. Twelve alpine kids were used to study the effects of chilling and meat pH on ion release. Free ions were measured in Longissimus dorsi muscle by capillary electrophoresis after water extraction. All free ion concentrations increased after death, but there were differences between ions. Temperature was not a factor affecting ion release in contrast to ultimate pH value. Three release mechanisms are believed to coexist: a passive binding to proteins, which stops as pH decreases, an active segregation which stops as ATP disappears and the production of metabolites due to anaerobic glycolysis.

  9. Energy distributions of plume ions from silver at different angles ablated in vacuum

    DEFF Research Database (Denmark)

    Christensen, Bo Toftmann; Schou, Jørgen; Canulescu, Stela

    A typical pulsed laser deposition (PLD) is carried out for a fluence between 0.5 and 2.5 J/cm2. The ablated particles are largely neutrals at the lowest fluence, but the fraction of ions increases strongly with fluence and accounts for more 0.5 of the particles at 2.5 J/cm2 [1,2]. Since it may...... be comparatively difficult to measure the energy and angular distribution of neutrals, measurements of the ionic fraction will be valuable for any modeling of PLD. We have irradiated silver in a vacuum chamber (~ 10-7 mbar) with a Nd:YAG laser at a wavelength of 355 nm and made detailed measurements of the time......-resolved angular distribution. The ion flow in different directions has been measured with a hemispherical array of Langmuir probes, by which the time-of-flight spectra the in all directions can be recorded [1,2]. In contrast to earlier work the beam spot was circular such that any flip-over effect of the plume...

  10. Thermal release behavior of helium from copper irradiated by He+ ions

    International Nuclear Information System (INIS)

    Yamauchi, T.; Tokura, S.; Yamanaka, S.; Miyake, M.

    1988-01-01

    Thermal release behavior of helium from copper irradiated by 20 keV He + ions with a dose of 2x10 15 to 3x10 17 ions/cm 2 has been studied. The shape of the thermal release curves and thew number of helium release peaks strongly depend on the irradiation dose. Results from SEM surface observastion after post-irradiation heating suggested that helium release caused various surface damages such as blistering, flaking, and hole formation. Helium release resulting in small holes was analyzed and helium bubble growth mechanisms are discussed. (orig.)

  11. Electrical properties of fast ion conducting silver based borate glasses: Application in solid battery

    International Nuclear Information System (INIS)

    Masoud, Emad M.; Khairy, M.; Mousa, M.A.

    2013-01-01

    Graphical abstract: -- Highlights: •AgI dopant created more opened borate network structure. •Dielectric constant and loss values increased with AgI concentration. •AgI dopant enhanced both ion migration and orientation. •0.6 AgI–0.27 Ag 2 O–0.13 B 2 O 3 showed the highest DC-conductivity at room temperature. •It showed also good life time as a solid electrolyte in solid battery at room temperature. -- Abstract: The electrical properties of the ternary ionic conducting glass system xAgI–(1 – x)[0.67Ag 2 O–0.33B 2 O 3 ], where x = 0.4 , 0.5, 0.6, 0.7 and 0.8, were studied for emphasizing the influence of silver iodide concentration on the transport properties in the based borate glasses. The glasses were prepared by melt quenching technique and characterized using X-ray diffraction (XRD), FT-IR spectra and differential thermal analysis (DTA). XRD confirmed a glassy nature for all investigated compositions. Electrical conductivity (σ), dielectric constant (ε′), dielectric loss (ε ″ ) and impedance spectra (Z′–Z′′) were studied for all samples at a frequency range of 0–10 6 Hz and over a temperature range of 303–413 K. Changes of conductivity and dielectric properties with composition, temperature and frequency were analyzed and discussed. A silver iodine battery using glassy electrolyte sample with the highest ionic conductivity (x = 0.6) was studied

  12. Neuron cell positioning on polystyrene in culture by silver-negative ion implantation and region control of neural outgrowth

    International Nuclear Information System (INIS)

    Tsuji, Hiroshi; Sato, Hiroko; Baba, Takahiro; Ikemura, Shin'ichi; Gotoh, Yasuhito; Ishikawa, Junzo

    2000-01-01

    A new method to control the position of neuron cell attachment and extension region of neural outgrowth has been developed by using a pattering ion implantation with silver-negative ions into polystyrene dishes. This technique offers a promising method to form an artificially designed neural network in cell culture in vitro. Silver-negative ions were implanted into non-treated polystyrene dishes (NTPS) at conditions of 20 keV and 3x10 15 ions/cm 2 through a pattering mask, which had as many as 67 slits of 60 μm in width and 4 mm in length with a spacing of 60 μm. For cell culture in vitro, nerve cells of PC-12h (rat adrenal phechromocytoma) were used because they respond to a nerve growth factor (NGF). In the first 2 days in culture without NGF, we observed a selective cell attachment only to the ion-implanted region in patterning Ag - implanted polystyrene sample (p-Ag/NTPS). In another 2 days in culture with NGF, the nerve cells expanded neurites only over the ion-implanted region. For collagen-coated p-Ag/NTPS sample of which collagen was coated after the ion implantation (Collagen/p-Ag/NTPS), most nerve cells were also attached on the ion-implanted region. However, neurites expanded in both ion-implanted and unimplanted regions. The contact angle of NTPS decreased after the ion implantation from 86 deg. to 74 deg. . The region selectivity of neuron attachment and neurite extension is considered to be due to contact angle lowering by the ion implantation as radiation effect on the surface

  13. Optimization for extracellular biosynthesis of silver nanoparticles by Penicillium aculeatum Su1 and their antimicrobial activity and cytotoxic effect compared with silver ions.

    Science.gov (United States)

    Ma, Liang; Su, Wei; Liu, Jian-Xin; Zeng, Xiao-Xi; Huang, Zhi; Li, Wen; Liu, Zheng-Chun; Tang, Jian-Xin

    2017-08-01

    The present study addresses an eco-friendly and energy-saving method for extracellular biosynthesis of silver nanoparticles (AgNPs) using a cell free filtrate of the fungus strain Penicillium aculeatum Su1 as a reducing agent. Parametric optimization of the biosynthesis process demonstrated different effects on the size, distribution, yield, and synthesis rate of biosynthesized AgNPs. The transmission electron microscopy (TEM) measurements demonstrated that AgNPs were spherical or approximately spherical, with a size between 4 and 55nm. High-resolution transmission electron microscopy (HR-TEM) and X-ray diffraction (XRD) analyses indicated that AgNPs were nanocrystalline by nature, with the character of a face-centered cubic (fcc). Fourier transform infrared spectroscopy (FTIR) analysis confirmed the existence of protein molecules that acted as a reducing agent and a capping agent during the biosynthesis process. Furthermore, the biosynthesized AgNPs exhibited higher antimicrobial activity than silver ions against Gram negative bacteria, Gram positive bacteria and fungi. Compared with silver ions, the biosynthesized AgNPs presented higher biocompatibility toward human bronchial epithelial (HBE) cells and high cytotoxicity in a dose-dependent manner with an IC 50 of 48.73μg/mL toward A549 cells. These results demonstrate that Penicillium aculeatum Su1 is a potential bioresource that can be used to produce low-cost and eco-friendly AgNPs as efficient antimicrobial agent, drug delivery vehicle or anticancer drug for clinic treatment. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Silver nanoparticle formation in thin oxide layer on silicon by silver-negative-ion implantation for Coulomb blockade at room temperature

    International Nuclear Information System (INIS)

    Tsuji, Hiroshi; Arai, Nobutoshi; Matsumoto, Takuya; Ueno, Kazuya; Gotoh, Yasuhito; Adachi, Kouichiro; Kotaki, Hiroshi; Ishikawa, Junzo

    2004-01-01

    Formation of silver nanoparticles formed by silver negative-ion implantation in a thin SiO 2 layer and its I-V characteristics were investigated for development single electron devices. In order to obtain effective Coulomb blockade phenomenon at room temperature, the isolated metal nanoparticles should be in very small size and be formed in a thin insulator layer such as gate oxide on the silicon substrate. Therefore, conditions of a fine particles size, high particle density and narrow distribution should be controlled at their formation without any electrical breakdown of the thin insulator layer. We have used a negative-ion implantation technique with an advantage of 'charge-up free' for insulators, with which no breakdown of thin oxide layer on Si was obtained. In the I-V characteristics with Au electrode, the current steps were observed with a voltage interval of about 0.12 V. From the step voltage the corresponded capacitance was calculated to be 0.7 aF. In one nanoparticle system, this value of capacitance could be given by a nanoparticle of about 3 nm in diameter. This consideration is consistent to the measured particle size in the cross-sectional TEM observation. Therefore, the observed I-V characteristics with steps are considered to be Coulomb staircase by the Ag nanoparticles

  15. 100 MeV silver ions induced defects and modifications in silica glass

    Energy Technology Data Exchange (ETDEWEB)

    Jadhav, Vijay S.; Deore, Avinash V.; Dahiwale, S.S. [Department of Physics, University of Pune, Pune 411007 (India); Kanjilal, D. [Inter University Accelerator Centre, New Delhi 110067 (India); Bhoraskar, V.N. [Department of Physics, University of Pune, Pune 411007 (India); Dhole, S.D., E-mail: sanjay@physics.unipune.ac.in [Department of Physics, University of Pune, Pune 411007 (India)

    2014-07-15

    Highlights: •Study of silver ion induced defects and modifications in silica glass. •Variation in oxygen deficiency centres (ODA-II) and nonbridging oxygen hole centres (NBOHC). •Study of structural damage in terms of Urbach energy. -- Abstract: A few silica glass samples having 1 cm{sup 2} area and 0.1 cm thickness were irradiated with 100 MeV energy Ag{sup 7+} ions for the fluences ranging from 1 × 10{sup 12} ions/cm{sup 2} to 5 × 10{sup 13} ions/cm{sup 2}. The optical properties and the corresponding induced defects were characterised by the techniques such as UV–Visible, Photoluminescence (PL), Fourier transform infrared (FTIR), and Electron spin resonance (ESR) spectroscopy. The UV–Visible absorption spectra show two peaks, one at 5 eV and another weak peak at 5.8 eV. A peak observed at 5.0 eV corresponds to B{sub 2} band (oxygen deficiency in SiO{sub 2} network) and the peak at 5.8 eV is due to the paramagnetic defects like E′ centre. The intensities of these peaks found to be increased with increase in ion fluence. It attributes to the increase in the concentration of E′ centres and B{sub 2} band respectively. In addition, the optical band gap energy, Urbach energy and the defects concentration have been calculated using Urbach plot. The optical band gap found to be decreased from 4.65 eV to 4.39 eV and the Urbach energy found to be increased from 60 meV to 162 meV. The defect concentration of nonbridging oxygen hole centres (NBOHC) and E′ centres are found to be increased to 1.69 × 10{sup 13} cm{sup −3} and 3.134 × 10{sup 14} cm{sup −3} respectively. In PL spectra, the peak appeared at 1.92 eV and 2.7 eV envisage the defects of nonbridging oxygen hole centres and B{sub 2α} oxygen deficient centres respectively. ESR spectra also confirms the existence of E′ and NBOHC centres. FTIR spectra shows scissioning of Si-O-Si bonds and the formation of Si-H and Si-OH bonds, which supports to the co-existence of the defects induced by Ag

  16. The production of ultra-thin layers of ion-exchange resin and metallic silver by electrospraying

    International Nuclear Information System (INIS)

    Wyllie, H.A.

    1988-10-01

    Highly efficient radioactive sources for use in radioisotope metrology have been prepared on ultra-thin layers of electrosprayed ion-exchange resin. The efficiency of these sources can be reduced for the purpose of radioactivity standardisation by coating them with conducting silver layers which are also produced by electrospraying. A description is given of improvements to the electrospraying methods, together with details of the rotating, oscillating source-mount turntable

  17. Silver ions increase plasma membrane permeability through modulation of intracellular calcium levels in tobacco BY-2 cells

    Czech Academy of Sciences Publication Activity Database

    Klíma, Petr; Laňková, Martina; Vandenbussche, F.; Van Der Straeten, D.; Petrášek, Jan

    2018-01-01

    Roč. 37, č. 5 (2018), s. 809-818 ISSN 0721-7714 R&D Projects: GA ČR GA16-10948S Grant - others:OPPK(XE) CZ.2.16/3.1.00/21519 Institutional support: RVO:61389030 Keywords : Auxin * Calcium * Ethylene * Silver ions * Tobacco BY-2 cells * Transmembrane transport Subject RIV: ED - Physiology OBOR OECD: Cell biology Impact factor: 2.869, year: 2016

  18. Ion release from orthodontic brackets in 3 mouthwashes: an in-vitro study.

    Science.gov (United States)

    Danaei, Shahla Momeni; Safavi, Afsaneh; Roeinpeikar, S M Mehdi; Oshagh, Morteza; Iranpour, Shiva; Omidkhoda, Maryam; Omidekhoda, Maryam

    2011-06-01

    Stainless steel orthodontic brackets can release metal ions into the saliva. Fluoridated mouthwashes are often recommended to orthodontic patients to reduce the risk of white-spot lesions around their brackets. However, little information is available regarding the effect of different mouthwashes in ion release of orthodontic brackets. The purpose of this study was to measure the amount of metal ion release from orthodontic brackets when kept in different mouthwashes. One hundred sixty stainless steel brackets (0.022-in, 3M Unitek, Monrovia, Calif) were divided randomly into 4 equal groups and immersed in Oral B (Procter & Gamble, Weybridge, United Kingdom), chlorhexidine (Shahdaru Labratories, Tehran, Iran), and Persica (Poursina Pharmaceutical Laboratories, Tehran, Iran) mouthwashes and distilled deionized water and incubated at 37°C for 45 days. Nickel, chromium, iron, copper, and manganese released from the orthodontic brackets were measured with an inductively coupled plasma spectrometer. For statistical analysis, 1-way analysis of variance (ANOVA) and the Duncan multiple-range tests were used. The results showed that ion release in deionized water was significantly (P 0.05) in nickel, chromium, iron, and copper ion release in the Oral B and Persica mouthwashes. The level of manganese release was significantly different in all 4 groups. If ion release is a concern, Oral B and Persica mouthwashes might be better options than chlorhexidine for orthodontic patients with stainless steel brackets. Copyright © 2011 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

  19. Investigation of the influence of silver and tin on the luminescence of trivalent europium ions in glass

    International Nuclear Information System (INIS)

    Jimenez, J.A.; Lysenko, S.; Liu, H.; Fachini, E.; Cabrera, C.R.

    2010-01-01

    Europium-doped aluminophosphate glasses prepared by the melt-quenching technique have been studied by photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS). The effects of silver and tin doping, and of further thermal processing on Eu 3+ ions luminescence have been assessed. For the glass system containing only europium, Eu 3+ PL observed under UV excitation is suggested to occur through energy transfer from the excited glass host. After silver and tin doping, an enhanced UV excited Eu 3+ PL has been indicated to occur essentially due to radiative energy transfer from isolated Ag + ions and/or two fold-coordinated Sn centers. Since thermal processing of the material leads to a quenching effect on Eu 3+ PL and Ag nanoparticles (NPs) formation due to reduction of silver ions by tin, XPS was employed in order to investigate the possibility for Eu 3+ →Eu 2+ reduction during HT as a potential source of the PL decrease. The data points towards Ag NPs as main responsible for the observed weakening of Eu 3+ PL.

  20. In situ synthesis of silver-nanoparticles/bacterial cellulose composites for slow-released antimicrobial wound dressing.

    Science.gov (United States)

    Wu, Jian; Zheng, Yudong; Song, Wenhui; Luan, Jiabin; Wen, Xiaoxiao; Wu, Zhigu; Chen, Xiaohua; Wang, Qi; Guo, Shaolin

    2014-02-15

    Bacterial cellulose has attracted increasing attention as a novel wound dressing material, but it has no antimicrobial activity, which is one of critical skin-barrier functions in wound healing. To overcome such deficiency, we developed a novel method to synthesize and impregnate silver nanoparticles on to bacterial cellulose nanofibres (AgNP-BC). Uniform spherical silver nano-particles (10-30 nm) were generated and self-assembled on the surface of BC nano-fibers, forming a stable and evenly distributed Ag nanoparticles coated BC nanofiber. Such hybrid nanostructure prevented Ag nanoparticles from dropping off BC network and thus minimized the toxicity of nanoparticles. Regardless the slow Ag(+) release, AgNP-BC still exhibited significant antibacterial activities with more than 99% reductions in Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. Moreover, AgNP-BC allowed attachment and growth of epidermal cells with no cytotoxicity emerged. The results demonstrated that AgNP-BC could reduce inflammation and promote wound healing. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Dermal exposure potential from textiles that contain silver nanoparticles.

    Science.gov (United States)

    Stefaniak, Aleksandr B; Duling, Mathew G; Lawrence, Robert B; Thomas, Treye A; LeBouf, Ryan F; Wade, Eleanor E; Virji, M Abbas

    2014-01-01

    Factors that influence exposure to silver particles from the use of textiles are not well understood. The aim of this study was to evaluate the influence of product treatment and physiological factors on silver release from two textiles. Atomic and absorbance spectroscopy, electron microscopy, and dynamic light scattering (DLS) were applied to characterize the chemical and physical properties of the textiles and evaluate silver release in artificial sweat and saliva under varying physiological conditions. One textile had silver incorporated into fiber threads (masterbatch process) and the other had silver nanoparticles coated on fiber surfaces (finishing process). Several complementary and confirmatory analytical techniques (spectroscopy, microscopy, etc.) were required to properly assess silver release. Silver released into artificial sweat or saliva was primarily in ionic form. In a simulated "use" and laundering experiment, the total cumulative amount of silver ion released was greater for the finishing process textile (0·51±0·04%) than the masterbatch process textile (0·21±0·01%); Pmasterbatch vs finishing) used to treat textile fibers was a more influential exposure factor than physiological properties of artificial sweat or saliva.

  2. Transport and solid state battery characteristic studies of silver based super ion conducting glasses

    International Nuclear Information System (INIS)

    Jayaseelan, S.; Muralidharan, P.; Venkateswarlu, M.; Satyanarayana, N.

    2005-01-01

    Silverarsenotellurite (SAT), silverphosphotellurite (SPT) and silvervanadotellurite (SVT) quaternary glass systems were prepared with various formers compositions by a melt quenching method. Glass nature, glass transition temperature (T g ) and structure of the prepared glasses were identified respectively by X-ray diffraction (XRD), differential scanning calorimetric (DSC) and Fourier transform infrared (FT-IR) technique. Electrical conductivity studies were carried out by impedance measurement in the frequency range 40 Hz to 100 KHz at different temperatures for all three sets of AgI-Ag 2 O-[TeO 2 -M 2 O 5 ] (M 2 O 5 = As 2 O 5 , P 2 O 5 , V 2 O 5 ) glasses. The high conducting compositions of SAT, SPT and SVT glass samples were fixed from the results of total conductivity (σ t ). Electronic conductivity (σ e ) studies were made on high conducting composition of each glass system by Wagner's polarization method. Total current (i t ) is due to ion and electron. Electronic current (i e ) due to electron were estimated through mobility studies. Ionic conductivity (σ i ) and ionic current (i i ) were calculated respectively using the conductivity (σ t and σ e ) and current (i t and i e ) results for the SAT, SPT and SVT glasses. Transport numbers due to ion (t i ) and electron (t e ) were calculated using the conductivity and mobility results for each glass system. The high conducting composition of the SAT, SPT and SVT glasses were used as solid electrolytes with silver metal as an anode and iodine:graphite (I:C) as a cathode for the fabrication of solid state batteries (SSBs). All the fabricated batteries were characterized by measuring the open circuit voltage (OCV) and polarization properties and estimated the batteries performances

  3. Surface analytical investigations of the release behaviour of volatile fission products during simulated core meltdown accidents and of the reaction behaviour of iodine with silver surfaces

    International Nuclear Information System (INIS)

    Moers, H.

    1986-07-01

    The report presents the results of the analysis of aerosol particles formed in simulated laboratory scale core meltdown experiments. In addition the interaction of silver surfaces with gaseous molecular iodine and with iodide and molecular iodine in aqueous solution was investigated. The composition of the aerosol samples and the progress of the reactions mentioned were determined by use of surface analytical techniques (X-ray photoelectron spectroscopy, Auger electron spectroscopy, secondary ion mass spectroscopy). The major information can be evaluated from X-ray photoelectron spectra which exhibit chemical shifts of the photoelectron lines which allowing a discrimination between different chemical species of the same element. The analyses showed that iodine is present in the aerosol particles mainly as caesium iodide and, to a smaller fraction, as silver iodide. During the adsorption of gaseous molecular iodine at metallic silver surfaces a closed silver iodide overlayer is formed. In aqueous iodide solutions one observes chemisorption of the iodide anions up to a coverage of the metallic silver surface of about half a monolayer. Molecular iodine in aqueous solution is completely converted to silver iodide which covers the substrate irregularly. (orig./HP) [de

  4. Peculiarities of the diffusion of silver and sodium ions in phosphate glasses with a high content of sodium oxide

    International Nuclear Information System (INIS)

    Syutkin, V.M.; Tolkatchev, V.A.

    1996-01-01

    The phosphate glasses with a high content of alkali metal ions are good ionic conductors. Despite active studies, the mechanism of ion diffusion is not so far clear. The present work discusses the characteristics of ion diffusion in phosphate glasses with a high content of sodium oxide. An effective method to study ion transport is the investigation of relaxation processes the kinetics of which depends on ion diffusion. We use the data for two types of relaxation processes the kinetics of which is determined by ion diffusion. This is the conductivity relaxation due to sodium (host) ions and the decay of radiation-induced centers controlled by silver (guest) ion diffusion. Both of the processes being actually the first-order processes display a nonexponential kinetic behavior. The relaxation law can be interpreted either as the inherently nonexponential function or as the weighted sum of exponential decay functions with a distribution of relaxation times. It has been demonstrated that on the molecular level the relaxation function should be interpreted in the frame of the scheme of parallel first-order processes. This fact allows one to formulate a number of features of ion diffusion: (i) the mean square displacement of ions does not exceed several angstrom when transport becomes non-dispersive; (ii) the diffusion coefficient of ions is the function of coordinates. In this case, a characteristic distance at which D(r) noticeably varies is no less than a hundred of angstrom; (iii) the instantaneous concentration of mobile ions is well below the overall concentration ions

  5. Redox behavior of transition metal ions in zeolites 6. Reversibility of the reduction reaction in silver zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Jacobs, P A; Uytterhoeven, J B; Beyer, H K

    1977-01-01

    Degassing above 573/sup 0/K of Ag-Y or Ag-mordenite previously reduced by hydrogen at 623/sup 0/K resulted in hydrogen evolution, the amount of hydrogen increasing to a maximum at about 873/sup 0/K. No hydrogen was evolved when the zeolite was reduced by hydrazine or hydroxylamine, indicating that hydrogen is formed by reaction between silver metal and hydroxyl groups formed in the reduction step (i.e., the reverse of the reduction step). Consumption of hydroxyl groups was proven by IR studies of pyridine chemisorption which occurs entirely as pyridinium ions on Broensted sites or reduced samples but with increasing formation of pyridine on Lewis acid sites as the degassing temperature increases; formation of silver(I) ions was proven by carbon monoxide complexation. Silver metal outside the zeolite pores was not affected by the degassing, and the amount of hydrogen evolved upon degassing decreased with increasing number of reduction-degassing cycles, probably as a result of dehydroxylation or sintering. Spectra, graphs, tables, and 21 references.

  6. Performance test of silver ion-exchanged zeolite for the removal of gaseous radioactive methyl iodide at high temperature condition

    International Nuclear Information System (INIS)

    Byung-Seon Choi; Geun-Il Park; Jung-Won Lee; Ho-Yeon Yang; Seung-Kon Ryu

    2003-01-01

    Performance tests of silver ion-exchanged zeolite (AgX) adsorbent for the control of radioiodine gas generated from a high-temperature process were carried out using both non-radioactive and a radioactive methyl iodide tracers. From the identification of SEM-EDAX analysis, an experimental result of silver ion-exchanged ratio containing 10∼30 wt% of Ag was fit to that calculated by the weight increment, and it was confirmed that the silver was uniformly distributed inside the pores of the adsorbent. Demonstration test of AgX-10 adsorbent using radioactive methyl iodide tracer was performed. The removal efficiency of radioiodine with AgX-10 in the temperature ranges of 150 to 300 deg C was in the ranges of 99.9% to 99.99%, except for 300 deg C. The influence of the long-term weathering and the poisoning with NO 2 gas (200 ppm) on adsorption capacity of AgX-10 was also analyzed. The removal efficiency of radioactive methyl iodide by AgX-10 weathered for 14 weeks was 99.95%. Long-term poisoning test showed that the adsorption efficiency of methyl iodide started to decrease after 10 weeks, and the removal efficiency of radioiodine by AgX-10, poisoned for 16 weeks, was 99% (DF=100). (author)

  7. Multi-instrumental Analysis of Tissues of Sunflower Plants Treated with Silver(I Ions – Plants as Bioindicators of Environmental Pollution

    Directory of Open Access Journals (Sweden)

    Rene Kizek

    2007-01-01

    Full Text Available The aim of this work is to investigate sunflower plants response on stressinduced by silver(I ions. The sunflower plants were exposed to silver(I ions (0, 0.1, 0.5,and 1 mM for 96 h. Primarily we aimed our attention to observation of basic physiologicalparameters. We found that the treated plants embodied growth depression, coloured changes and lack root hairs. Using of autofluorescence of anatomical structures, such aslignified cell walls, it was possible to determine the changes of important shoot and rootstructures, mainly vascular bungles and development of secondary thickening. Thedifferences in vascular bundles organisation, parenchymatic pith development in the rootcentre and the reduction of phloem part of vascular bundles were well observable.Moreover with increasing silver(I ions concentration the vitality of rhizodermal cellsdeclined; rhizodermal cells early necrosed and were replaced by the cells of exodermis.Further we employed laser induced breakdown spectroscopy for determination of spatialdistribution of silver(I ions in tissues of the treated plants. The Ag is accumulated mainlyin near-root part of the sample. Moreover basic biochemical indicators of environmentalstress were investigated. The total content of proteins expressively decreased withincreasing silver(I ions dose and the time of the treatment. As we compare the resultsobtained by protein analysis – the total protein contents in shoot as well as root parts – wecan assume on the transport of the proteins from the roots to shoots. This phenomenon canbe related with the cascade of processes connecting with photosynthesis. The secondbiochemical parameter, which we investigated, was urease activity. If we compared theactivity in treated plants with control, we found out that presence of silver(I ions markedlyenhanced the activity of urease at all applied doses of this toxic metal. Finally we studiedthe effect of silver(I ions on activity of urease

  8. Nickel and chromium ion release from stainless steel bracket on immersion various types of mouthwashes

    Science.gov (United States)

    Mihardjanti, M.; Ismah, N.; Purwanegara, M. K.

    2017-08-01

    The stainless steel bracket is widely used in orthodontics because of its mechanical properties, strength, and good biocompatibility. However, under certain conditions, it can be susceptible to corrosion. Studies have reported that the release of nickel and chromium ions because of corrosion can cause allergic reactions in some individuals and are mutagenic. The condition of the oral environment can lead to corrosion, and one factor that can alter the oral environment is mouthwash. The aim of this study was to measure the nickel and chromium ions released from stainless steel brackets when immersed in mouthwash and aquadest. The objects consisted of four groups of 17 maxillary premolar brackets with .022 slots. Each group was immersed in a different mouthwash and aquadest and incubated at 37 °C for 30 days. After 30 days of immersion, the released ions were measured using the ICP-MS (Inductively Coupled Plasma-Mass Spectrometer). For statistical analysis, both the Kruskal-Wallis and Mann-Whitney tests were used. The results showed differences among the four groups in the nickel ions released (p < 0.05) and the chromium ions released (p < 0.5). In conclusion, the ions released as a result of mouthwash immersion have a small value that is below the limit of daily intake recommended by the World Health Organization.

  9. Determination of metal ions released by stainless steel arch bar into bio-fluids

    Directory of Open Access Journals (Sweden)

    Lori A. Joseph

    2009-04-01

    Full Text Available The amounts of cobalt, iron, manganese, nickel and chromium ions released from new and reused stainless steel arch bar used for maxillomandibular fixation was determined in Hank’s solutions of different hydrogen and chloride ions concentrations, whole blood serum and phosphate buffered saline (PBS in vitro, over a six-week immersion time at 37 oC, by atomic absorption spectrophotometry. The corrosion levels of the wires due to effects of media and incubation times in the bio-fluids were compared by Duncan’s two-way ANOVA (P less than 0.05. Pearson’s correlation was used in establishing relationship in the amounts of metal ions released by new and reused arch bars. The study indicated that the reused wires released more ions than new ones at all time points. The variation of pH and chloride ions of the bio-fluids had a significant effect on the amount of Ni, Mn and Cr ions released. Ageing prior use of arch bars significantly increased Ni ions released into the bio-fluids.

  10. Ammonium ion interaction with conditioned natural zeolite with silver and its effect on the disinfection of polluted water in front of a consortium of gram (+) and gram (-) microorganisms

    International Nuclear Information System (INIS)

    Gonzaga G, V. E.

    2013-01-01

    Clinoptilolite zeolite material is a relative abundance in Mexico, which has ion exchange properties, therefore, has the ability to retain metal ions giving it an application in the process of disinfecting of water contaminated with pathogenic microorganisms. In this research, we conducted a study of disinfection of water contaminated with a microbial consortium, from a zeolite rock clinoptilolite from a deposit located in the State of Guerrero. Initially, the zeolite prepared by the grinding and sieving, for conditioning with NaCl and subsequently with AgNO 3 , finally to be characterized using the techniques of scanning electron microscopy and X-ray diffraction. Tests using columns packed with zeolite material, the effect of zeolite bactericidal conditioned with silver (ZGAg) against a microbial consortium consisting of Escherichia coli and Sthapyloccocus aureus in aqueous solution in the presence of ammonium ions used to increase the ion exchange with zeolite fitted with silver. To describe curves disinfecting a continuous flow system is adapted Gu pta model, which describes the kinetics and equilibrium adsorption process, considering the microorganisms as the adsorbate and the sanitizing agent (conditioned with silver zeolite) as the adsorbent. Characterization results show that in the scanning electron microscopy (Sem), no changes were obtained on the morphology of typical clinoptilolite crystals before and after that was modified with sodium and then with silver, it is worth mentioning however that fitted with silver zeolite (ZGAg), small particles are seen on the zeolite material which when analyzed by energy dispersive spectroscopy (EDS), we found a high concentration of Ag +. The disinfection period is increased as the concentration increased ammonium ions, this behavior is attributed to the ion exchange that occurs between the ammonium ions and silver ions. A lower percentage of inactivation is due, therefore, to a lesser amount of money available to be

  11. Biocompatible silver nanoparticles embedded in a PEG–PLA polymeric matrix for stimulated laser light drug release

    International Nuclear Information System (INIS)

    Neri, F.; Scala, A.; Grimato, S.; Santoro, M.; Spadaro, S.; Barreca, F.; Cimino, F.; Speciale, A.; Saija, A.; Grassi, G.; Fazio, E.

    2016-01-01

    The laser-induced release of a well-known hepatoprotective drug (silibinin, SLB) from a temperature-sensitive polymeric composite loaded with silver nanoparticles (Ag NPs) was investigated. The surface chemistry tuning and the specific design of Ag NPs are fundamental in view of the engineering of specific stimuli-responsive systems, able to control drug release in response to external stimuli. The release profiles of SLB from the newly synthesized PEG–PLA@Ag composite show strong dependences on laser wavelength and Ag NPs’ Surface Plasmon Resonance (SPR). The resonant laser light excites the SPR of the NPs and the absorbed energy is converted into heat due to electron–photon collisions. The heat generated from the nanometer-sized metal particles embedded within the polymer is efficient and strongly localized. The nanovector, irradiated by a relatively low-intensity laser but tuned specifically to the metal NPs’ SPR, releases the encapsulated drug with a higher efficiency than that not irradiated or irradiated with a laser wavelength far from the metal SPR. A combination of analytical techniques including UV–Vis, NMR, and FT-IR spectroscopy and scanning/transmission electron microscopy has been used to study the structural and morphological properties of the composite. The controllable specificity of this approach and the possibility of the SPR-mediated localized photothermal effect to be usefully applied in aqueous environments are the relevant advances of the proposed system for photothermal therapies that make use of visible optical radiation or for the drug delivery in proximity of the tumor cells.

  12. Biocompatible silver nanoparticles embedded in a PEG–PLA polymeric matrix for stimulated laser light drug release

    Energy Technology Data Exchange (ETDEWEB)

    Neri, F. [Università di Messina, Dipartimento di Scienze Matematiche e Informatiche, Scienze Fisiche e Scienze della Terra (Italy); Scala, A., E-mail: ascala@unime.it; Grimato, S. [Università di Messina, Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali (Italy); Santoro, M.; Spadaro, S.; Barreca, F. [Università di Messina, Dipartimento di Scienze Matematiche e Informatiche, Scienze Fisiche e Scienze della Terra (Italy); Cimino, F.; Speciale, A.; Saija, A.; Grassi, G. [Università di Messina, Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali (Italy); Fazio, E., E-mail: enfazio@unime.it [Università di Messina, Dipartimento di Scienze Matematiche e Informatiche, Scienze Fisiche e Scienze della Terra (Italy)

    2016-06-15

    The laser-induced release of a well-known hepatoprotective drug (silibinin, SLB) from a temperature-sensitive polymeric composite loaded with silver nanoparticles (Ag NPs) was investigated. The surface chemistry tuning and the specific design of Ag NPs are fundamental in view of the engineering of specific stimuli-responsive systems, able to control drug release in response to external stimuli. The release profiles of SLB from the newly synthesized PEG–PLA@Ag composite show strong dependences on laser wavelength and Ag NPs’ Surface Plasmon Resonance (SPR). The resonant laser light excites the SPR of the NPs and the absorbed energy is converted into heat due to electron–photon collisions. The heat generated from the nanometer-sized metal particles embedded within the polymer is efficient and strongly localized. The nanovector, irradiated by a relatively low-intensity laser but tuned specifically to the metal NPs’ SPR, releases the encapsulated drug with a higher efficiency than that not irradiated or irradiated with a laser wavelength far from the metal SPR. A combination of analytical techniques including UV–Vis, NMR, and FT-IR spectroscopy and scanning/transmission electron microscopy has been used to study the structural and morphological properties of the composite. The controllable specificity of this approach and the possibility of the SPR-mediated localized photothermal effect to be usefully applied in aqueous environments are the relevant advances of the proposed system for photothermal therapies that make use of visible optical radiation or for the drug delivery in proximity of the tumor cells.

  13. Potentiometric detection of silver (I) ion based on carbon paste electrode modified with diazo-thiophenol-functionalized nanoporous silica gel

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Ting; Chai Yaqin, E-mail: yqchai@swu.edu.cn; Yuan Ruo; Guo Junxiang

    2012-07-01

    For the first time, triazene compound functionalized silica gel was incorporated into carbon paste electrode for the potentiometric detection of silver (I) ion. A novel diazo-thiophenol-functionalized silica gel (DTPSG) was synthesized, and the presence of DTPSG acted as not only a paste binder, but also a reactive material. The electrode with optimum composition, exhibited an excellent Nernstian response to Ag{sup +} ion ranging from 1.0 Multiplication-Sign 10{sup -6} to 1.0 Multiplication-Sign 10{sup -1} M with a detection limit of 9.5 Multiplication-Sign 10{sup -7} M and a slope of 60.4 {+-} 0.2 mV dec{sup -1} over a wide pH range (4.0-9.0) with a fast response time (50 s) at 25 Degree-Sign C. The electrode also showed a long-time stability, high selectivity and reproducibility. The response mechanism of the proposed electrode was investigated by using AC impedance. Moreover, the electrode was successfully applied for the determination of silver ions in radiology films, and for potentiometric titration of the mixture solution of Cl{sup -} and Br{sup -} ions. - Highlights: Black-Right-Pointing-Pointer Functionalized silica gels have become promising materials. Black-Right-Pointing-Pointer This work is the first attempt to apply triazene functionalized silica gel. Black-Right-Pointing-Pointer The Functionalized silica gels were used to detect silver. Black-Right-Pointing-Pointer The response of the previously reported papers are compared with this work. Black-Right-Pointing-Pointer The result indicates the proposed electrode is better than reported Ag{sup +} electrodes.

  14. Potentiometric detection of silver (I) ion based on carbon paste electrode modified with diazo-thiophenol-functionalized nanoporous silica gel

    International Nuclear Information System (INIS)

    Zhang Ting; Chai Yaqin; Yuan Ruo; Guo Junxiang

    2012-01-01

    For the first time, triazene compound functionalized silica gel was incorporated into carbon paste electrode for the potentiometric detection of silver (I) ion. A novel diazo-thiophenol-functionalized silica gel (DTPSG) was synthesized, and the presence of DTPSG acted as not only a paste binder, but also a reactive material. The electrode with optimum composition, exhibited an excellent Nernstian response to Ag + ion ranging from 1.0 × 10 −6 to 1.0 × 10 −1 M with a detection limit of 9.5 × 10 −7 M and a slope of 60.4 ± 0.2 mV dec −1 over a wide pH range (4.0–9.0) with a fast response time (50 s) at 25 °C. The electrode also showed a long-time stability, high selectivity and reproducibility. The response mechanism of the proposed electrode was investigated by using AC impedance. Moreover, the electrode was successfully applied for the determination of silver ions in radiology films, and for potentiometric titration of the mixture solution of Cl − and Br − ions. - Highlights: ► Functionalized silica gels have become promising materials. ► This work is the first attempt to apply triazene functionalized silica gel. ► The Functionalized silica gels were used to detect silver. ► The response of the previously reported papers are compared with this work. ► The result indicates the proposed electrode is better than reported Ag + electrodes.

  15. Release of nickel and chromium ions from orthodontic wires following the use of teeth whitening mouthwashes

    Directory of Open Access Journals (Sweden)

    AmirHossein Mirhashemi

    2018-02-01

    Full Text Available Abstract Background Corrosion resistance is an important requirement for orthodontic appliances. Nickel and chromium may be released from orthodontic wires and can cause allergic reactions and cytotoxicity when patients use various mouthwashes to whiten their teeth. Our study aimed to assess the release of nickel and chromium ions from nickel titanium (NiTi and stainless steel (SS orthodontic wires following the use of four common mouthwashes available on the market. Methods This in vitro, experimental study was conducted on 120 orthodontic appliances for one maxillary quadrant including five brackets, one band and half of the required length of SS, and NiTi wires. The samples were immersed in Oral B, Oral B 3D White Luxe, Listerine, and Listerine Advance White for 1, 6, 24, and 168 h. The samples immersed in distilled water served as the control group. Atomic absorption spectroscopy served to quantify the amount of released ions. Results Nickel ions were released from both wires at all time-points; the highest amount was in Listerine and the lowest in Oral B mouthwashes. The remaining two solutions were in-between this range. The process of release of chromium from the SS wire was the same as that of nickel. However, the release trend in NiTi wires was not uniform. Conclusions Listerine caused the highest release of ions. Listerine Advance White, Oral B 3D White Luxe, and distilled water were the same in terms of ion release. Oral B showed the lowest amount of ion release.

  16. A review of the antibacterial effects of silver nanomaterials and potential implications for human health and the environment

    Science.gov (United States)

    Marambio-Jones, Catalina; Hoek, Eric M. V.

    2010-06-01

    Here, we present a review of the antibacterial effects of silver nanomaterials, including proposed antibacterial mechanisms and possible toxicity to higher organisms. For purpose of this review, silver nanomaterials include silver nanoparticles, stabilized silver salts, silver-dendrimer, polymer and metal oxide composites, and silver-impregnated zeolite and activated carbon materials. While there is some evidence that silver nanoparticles can directly damage bacteria cell membranes, silver nanomaterials appear to exert bacteriocidal activity predominantly through release of silver ions followed (individually or in combination) by increased membrane permeability, loss of the proton motive force, inducing de-energization of the cells and efflux of phosphate, leakage of cellular content, and disruption DNA replication. Eukaryotic cells could be similarly impacted by most of these mechanisms and, indeed, a small but growing body of literature supports this concern. Most antimicrobial studies are performed in simple aquatic media or cell culture media without proper characterization of silver nanomaterial stability (aggregation, dissolution, and re-precipitation). Silver nanoparticle stability is governed by particle size, shape, and capping agents as well as solution pH, ionic strength, specific ions and ligands, and organic macromolecules—all of which influence silver nanoparticle stability and bioavailability. Although none of the studies reviewed definitively proved any immediate impacts to human health or the environment by a silver nanomaterial containing product, the entirety of the science reviewed suggests some caution and further research are warranted given the already widespread and rapidly growing use of silver nanomaterials.

  17. A review of the antibacterial effects of silver nanomaterials and potential implications for human health and the environment

    Energy Technology Data Exchange (ETDEWEB)

    Marambio-Jones, Catalina; Hoek, Eric M. V., E-mail: emvhoek@ucla.ed [University of California, Los Angeles, Department of Civil and Environmental Engineering, California NanoSystems Institute (United States)

    2010-06-15

    Here, we present a review of the antibacterial effects of silver nanomaterials, including proposed antibacterial mechanisms and possible toxicity to higher organisms. For purpose of this review, silver nanomaterials include silver nanoparticles, stabilized silver salts, silver-dendrimer, polymer and metal oxide composites, and silver-impregnated zeolite and activated carbon materials. While there is some evidence that silver nanoparticles can directly damage bacteria cell membranes, silver nanomaterials appear to exert bacteriocidal activity predominantly through release of silver ions followed (individually or in combination) by increased membrane permeability, loss of the proton motive force, inducing de-energization of the cells and efflux of phosphate, leakage of cellular content, and disruption DNA replication. Eukaryotic cells could be similarly impacted by most of these mechanisms and, indeed, a small but growing body of literature supports this concern. Most antimicrobial studies are performed in simple aquatic media or cell culture media without proper characterization of silver nanomaterial stability (aggregation, dissolution, and re-precipitation). Silver nanoparticle stability is governed by particle size, shape, and capping agents as well as solution pH, ionic strength, specific ions and ligands, and organic macromolecules-all of which influence silver nanoparticle stability and bioavailability. Although none of the studies reviewed definitively proved any immediate impacts to human health or the environment by a silver nanomaterial containing product, the entirety of the science reviewed suggests some caution and further research are warranted given the already widespread and rapidly growing use of silver nanomaterials.

  18. A review of the antibacterial effects of silver nanomaterials and potential implications for human health and the environment

    International Nuclear Information System (INIS)

    Marambio-Jones, Catalina; Hoek, Eric M. V.

    2010-01-01

    Here, we present a review of the antibacterial effects of silver nanomaterials, including proposed antibacterial mechanisms and possible toxicity to higher organisms. For purpose of this review, silver nanomaterials include silver nanoparticles, stabilized silver salts, silver-dendrimer, polymer and metal oxide composites, and silver-impregnated zeolite and activated carbon materials. While there is some evidence that silver nanoparticles can directly damage bacteria cell membranes, silver nanomaterials appear to exert bacteriocidal activity predominantly through release of silver ions followed (individually or in combination) by increased membrane permeability, loss of the proton motive force, inducing de-energization of the cells and efflux of phosphate, leakage of cellular content, and disruption DNA replication. Eukaryotic cells could be similarly impacted by most of these mechanisms and, indeed, a small but growing body of literature supports this concern. Most antimicrobial studies are performed in simple aquatic media or cell culture media without proper characterization of silver nanomaterial stability (aggregation, dissolution, and re-precipitation). Silver nanoparticle stability is governed by particle size, shape, and capping agents as well as solution pH, ionic strength, specific ions and ligands, and organic macromolecules-all of which influence silver nanoparticle stability and bioavailability. Although none of the studies reviewed definitively proved any immediate impacts to human health or the environment by a silver nanomaterial containing product, the entirety of the science reviewed suggests some caution and further research are warranted given the already widespread and rapidly growing use of silver nanomaterials.

  19. Improved separation of conjugated fatty acid methyl esters by silver ion-high-performance liquid chromatography.

    Science.gov (United States)

    Sehat, N; Rickert, R; Mossoba, M M; Kramer, J K; Yurawecz, M P; Roach, J A; Adlof, R O; Morehouse, K M; Fritsche, J; Eulitz, K D; Steinhart, H; Ku, Y

    1999-04-01

    Operating from one to six silver ion-high-performance liquid chromatography (Ag+-HPLC) columns in series progressively improved the resolution of the methyl esters of conjugated linoleic acid (CLA) isomeric mixtures from natural and commercial products. In natural products, the 8 trans, 10 cis-octadecadienoic (18:2) acid was resolved from the more abundant 7 trans, 9 cis-18:2, and the 10 trans, 12 cis-18:2 was separated from the major 9 cis, 11 trans-18:2 peak. In addition, both 11 trans, 13 cis-18:2 and 11 cis, 13 trans-18:2 isomers were found in natural products and were separated; the presence of the latter, 11 cis, 13 trans-18:2, was established in commercial CLA preparations. Three Ag+-HPLC columns in series appeared to be the best compromise to obtain satisfactory resolution of most CLA isomers found in natural products. A single Ag+-HPLC column in series with one of several normal-phase columns did not improve the resolution of CLA isomers as compared to that of the former alone. The 20:2 conjugated fatty acid isomers 11 cis, 13 trans-20:2 and 12 trans, 14 cis-20:2, which were synthesized by alkali isomerization from 11 cis, 14 cis-20:2, eluted in the same region of the Ag+-HPLC chromatogram just before the corresponding geometric CLA isomers. Therefore, CLA isomers will require isolation based on chain length prior to Ag+-HPLC separation. The positions of conjugated double bonds in 20:2 and 18:2 isomers were established by gas chromatography-electron ionization mass spectrometry as their 4,4-dimethyloxazoline derivatives. The double-bond geometry was determined by gas chromatography-direct deposition-Fourier transform infrared spectroscopy and by the Ag+-HPLC relative elution order.

  20. Differential Response of Floating and Submerged Leaves of Longleaf Pondweed to Silver Ions

    Directory of Open Access Journals (Sweden)

    Nisha Shabnam

    2017-06-01

    Full Text Available In this study, we have investigated variations in the potential of floating and submerged leaves of longleaf pondweed (Potamogeton nodosus to withstand silver ion (Ag+-toxicity. Both floating and submerged leaves changed clear colorless AgNO3 solutions to colloidal brown in the presence of light. Transmission electron microscopy revealed the presence of distinct crystalline Ag-nanoparticles (Ag-NPs in these brown solutions. Powder X-ray diffraction pattern showed that Ag-NPs were composed of Ag0 and Ag2O. Photosystem (PS II efficiency of leaves declined upon exposure to Ag+ with a significantly higher decline in the submerged leaves than in the floating leaves. Similarly, Ag+ treatment caused a significant reduction in the carboxylase activity of the ribulose bisphosphate carboxylase/oxygenase in leaves. The reduction in this carboxylase activity was significantly higher in the submerged than in the floating leaves. Ag+ treatment also resulted in a significant decline in the levels of non-enzymatic and enzymatic antioxidants; the decline was significantly lower in the floating than in submerged leaves. X-ray photoelectron spectroscopy revealed the presence of Ag2O in these leaves. Inductively coupled plasma mass spectrometry analysis revealed a three-fold higher Ag content in the submerged than in floating leaves. Our study demonstrates that floating leaves of longleaf pondweed have a superior potential to counter Ag+-toxicity compared with submerged leaves, which could be due to superior potential of floating leaves to reduce Ag+ to less/non-toxic Ag0/Ag2O-nanoparticles/nanocomplexes. We suggest that modulating the genotype of longleaf pondweed to bear higher proportion of floating leaves would help in cleaning fresh water bodies contaminated with ionic forms of heavy metals.

  1. Characterization and Comparison of Photocatalytic Activity Silver Ion doped on TiO2(TiO2/Ag+) and Silver Ion doped on Black TiO2(Black TiO2/Ag+)

    Science.gov (United States)

    Kim, Jin Yi; Sim, Ho Hyung; Song, Sinae; Noh, Yeoung Ah; Lee, Hong Woon; Taik Kim, Hee

    2018-03-01

    Titanium dioxide (TiO2) is one of the representative ceramic materials containing photocatalyst, optic and antibacterial activity. The hydroxyl radical in TiO2 applies to the intensive oxidizing agent, hence TiO2 is suitable to use photocatalytic materials. Black TiO2was prepared through reduction of amorphous TiO2 conducting under H2 which leads to color changes. Its black color is proven that absorbs 100% light across the whole-visible light, drawing enhancement of photocatalytic property. In this study, we aimed to compare the photocatalytic activity of silver ion doped on TiO2(TiO2/Ag+) and silver ion doped on black TiO2(black TiO2/Ag+) under visible light range. TiO2/Ag+ was fabricated following steps. 1) TiO2 was synthesized by a sol-gel method from Titanium tetraisopropoxide (TTIP). 2) Then AgNO3 was added during an aging process step for silver ion doping on the surface of TiO2. Moreover, Black TiO2/Ag+ was obtained same as TiO2/Ag+ except for calcination under H2. The samples were characterized X-ray diffraction (XRD), UV-visible reflectance (UV-vis DRS), and Methylene Blue degradation test. XRD analysis confirmed morphology of TiO2. The band gap of black TiO2/Ag+ was confirmed (2.6 eV) through UV-vis DRS, which was lower than TiO2/Ag+ (2.9 eV). The photocatalytic effect was conducted by methylene blue degradation test. It demonstrated that black TiO2/Ag+ had a photocatalytic effect under UV light also visible light.

  2. Silver ion mediated shape control of platinum nanoparticles: Removal of silver by selective etching leads to increased catalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Grass, Michael E.; Yue, Yao; Habas, Susan E.; Rioux, Robert M.; Teall, Chelsea I.; Somorjai, G.A.

    2008-01-09

    A procedure has been developed for the selective etching of Ag from Pt nanoparticles of well-defined shape, resulting in the formation of elementally-pure Pt cubes, cuboctahedra, or octahedra, with a largest vertex-to-vertex distance of {approx}9.5 nm from Ag-modified Pt nanoparticles. A nitric acid etching process was applied Pt nanoparticles supported on mesoporous silica, as well as nanoparticles dispersed in aqueous solution. The characterization of the silica-supported particles by XRD, TEM, and N{sub 2} adsorption measurements demonstrated that the structure of the nanoparticles and the mesoporous support remained conserved during etching in concentrated nitric acid. Both elemental analysis and ethylene hydrogenation indicated etching of Ag is only effective when [HNO{sub 3}] {ge} 7 M; below this concentration, the removal of Ag is only {approx}10%. Ethylene hydrogenation activity increased by four orders of magnitude after the etching of Pt octahedra that contained the highest fraction of silver. High-resolution transmission electron microscopy of the unsupported particles after etching demonstrated that etching does not alter the surface structure of the Pt nanoparticles. High [HNO{sub 3}] led to the decomposition of the capping agent, polyvinylpyrollidone (PVP); infrared spectroscopy confirmed that many decomposition products were present on the surface during etching, including carbon monoxide.

  3. Magnified fluorescence detection of silver(I) ion in aqueous solutions by using nano-graphite-DNA hybrid and DNase I.

    Science.gov (United States)

    Wei, Yin; Li, Bianmiao; Wang, Xu; Duan, Yixiang

    2014-08-15

    This paper describes a novel approach utilizing nano-graphite-DNA hybrid and DNase I for the amplified detection of silver(I) ion in aqueous solutions for the first time. Nano-graphite can effectively quench the fluorescence of dye-labeled cytosine-rich single-stranded DNA due to its strong π-π stacking interactions; however, in the presence of Ag(+), C-Ag(+)-C coordination induces the probe to fold into a hairpin structure, which does not adsorb on the surface of nano-graphite and thus retains the dye fluorescence. Meanwhile, the hairpin structure can be cleaved by DNase I, and in such case Ag(+) is delivered from the complex. The released Ag(+) then binds other dye-labeled single-stranded DNA on the nano-graphite surface, and touches off another target recycling, resulting in the successive release of dye-labeled single-stranded DNA from the nano-graphite, which leads to significant amplification of the signal. The present magnification sensing system exhibits high sensitivity toward Ag(+) with a limit of detection of 0.3nM (S/N=3), which is much lower than the standard for Ag(+) in drinking water recommended by the Environmental Protection Agency (EPA). The selectivity of the sensor for Ag(+) against other biologically and environmentally related metal ions is outstanding due to the high specificity of C-Ag(+)-C formation. Moreover, the sensing system is used for the determination of Ag(+) in river water samples with satisfying results. The proposed assay is simple, cost-effective, and might open the door for the development of new assays for other metal ions or biomolecules. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. The effect of loading solution and dissolution media on release of Diclofenac from ion exchange resins

    Directory of Open Access Journals (Sweden)

    "Atyabi F

    2002-07-01

    Full Text Available Drugs can be loaded on ion exchange resins in order to control their release. Loading of diclofenac sodium on the resin beads not only sustain its release but also reduce its gastrointestinal mucosal injury. In this study the effect of loading solution and concentration of diclofenac in loading solution on total amount of drug loaded on the resin beads (Amberlite IRA-900 and the release characteristic of drug in different media were examined. Results showed that diclofenac resin complex did not release their drug content in simulated gastric fluid but released it in simulated intestinal fluid independent of exposure time in acidic conditions. The effect of a number of parameters such as ionic strength and pH on the release characteristic of drug - resin complexes were also examined. Results showed that although ionic strength is an important factor, drug release is more affected by the pH of the media. NO ABSTRACT

  5. Short-term soil bioassays may not reveal the full toxicity potential for nanomaterials; bioavailability and toxicity of silver ions (AgNO3) and silver nanoparticles to earthworm Eisenia fetida in long-term aged soils

    International Nuclear Information System (INIS)

    Diez-Ortiz, Maria; Lahive, Elma; George, Suzanne; Ter Schure, Anneke; Van Gestel, Cornelis A.M.; Jurkschat, Kerstin; Svendsen, Claus; Spurgeon, David J.

    2015-01-01

    This study investigated if standard risk assessment hazard tests are long enough to adequately provide the worst case exposure for nanomaterials. This study therefore determined the comparative effects of the aging on the bioavailability and toxicity to earthworms of soils dosed with silver ions and silver nanoparticles (Ag NP) for 1, 9, 30 & 52 weeks, and related this to the total Ag in the soil, Ag in soil pore water and earthworm tissue Ag concentrations. For ionic Ag, a classical pattern of reduced bioavailability and toxicity with time aged in the soil was observed. For the Ag NP, toxicity increased with time apparently driven by Ag ion dissolution from the added Ag NPs. Internal Ag in the earthworms did not always explain toxicity and suggested the presence of an internalised, low-toxicity Ag fraction (as intact or transformed NPs) after shorter aging times. Our results indicate that short-term exposures, without long-term soil aging, are not able to properly assess the environmental risk of Ag NPs and that ultimately, with aging time, Ag ion and Ag NP effect will merge to a common value. - Highlights: • Toxicity of silver nanoparticles in soils increased with time. • Standard tests do not adequately assess toxicity of silver NPs to earthworms. • Internal Ag in earthworms did not always explain toxicity after shorter aging times. • With aging time, Ag ion and Ag NP effect in soils will merge to a common value. - Toxicity of silver nanoparticles in soils increased with time with the result that commonly applied tests of 28 days exposure with freshly spiked soils do not adequately assess the environmental hazard of silver nanoparticles

  6. Implantation of titanium, chromium, yttrium, molybdenum, silver, hafnium, tantalum, tungsten and platinum ions generated by a metal vapor vacuum ion source into 440C stainless steel

    International Nuclear Information System (INIS)

    Sasaki, Jun; Hayashi, Kazunori; Sugiyama, Kenji; Ichiko, Osami; Hashiguchi, Yoshihiro

    1992-01-01

    Titanium, yttrium, molybdenum, silver, chromium, hafnium, tantalum, tungsten and platinum ions generated by a metal vapor vacuum arc (MEVVA) ion source were implanted into 440C stainless steel in the dose region 10 17 ions cm -2 with extraction voltages of up to 70 kV. Glow discharge spectroscopy (GDS), friction coefficient, and Vickers microhardness of the specimens were studied. Grooves made by friction tests were investigated by electron probe microanalysis (EPMA). GDS showed incorporation of carbon in the yttrium, hafnium, tantalum, tungsten and platinum implanted specimens, as well as titanium implanted samples. A large amount of oxygen was observed in the yttrium implanted specimen. The friction coefficient was measured by reciprocating sliding of an unimplanted 440C ball without lubricant at a load of 0.245 N. The friction decreased and achieved a stable state after implantation of titanium, hafnium and tantalum. The friction coefficient of the platinum implanted specimen showed a gradual decrease after several cycles of sliding at high friction coefficient. The yttrium implanted sample exhibited a decreased but slightly unstable friction coefficient. Results from EPMA showed that the implanted elements, which gave decreased friction, remained even after sliding of 200 cycles. Implantation of chromium, molybdenum, silver and tungsten did not provide a decrease in friction and the implants were gone from the wear grooves after the sliding tests. (orig.)

  7. Short-term soil bioassays may not reveal the full toxicity potential for nanomaterials; bioavailability and toxicity of silver ions (AgNO3) and silver nanoparticles to earthworm Eisenia fetida in long-term aged soils

    NARCIS (Netherlands)

    Diez-Ortiz, M.; Lahive, E.; George, S.; Ter Schure, A.; van Gestel, C.A.M.; Jurkschat, K.; Svendsen, C.; Spurgeon, D.J.

    2015-01-01

    This study investigated if standard risk assessment hazard tests are long enough to adequately provide the worst case exposure for nanomaterials. This study therefore determined the comparative effects of the aging on the bioavailability and toxicity to earthworms of soils dosed with silver ions and

  8. Amalgamation based optical and colorimetric sensing of mercury(II) ions with silver graphene oxide nanocomposite materials

    International Nuclear Information System (INIS)

    Kamali, Khosro Zangeneh; Pandikumar, Alagarsamy; Jayabal, Subramaniam; Huang, Nay Ming; Ramaraj, Ramasamy; Lim, Hong Ngee; Ong, Boon Hoong; Bien, Chia Sheng Daniel; Kee, Yeh Yee

    2016-01-01

    The article describes a facile method for the preparation of a conjugate composed of silver nanoparticles and graphene oxide (Ag GO) via chemical reduction of silver precursors in the presence of graphene oxide (GO) while sonicating the solution. The Ag GO was characterized by X-ray photoelectron spectroscopy, X-ray powder diffraction, and energy-dispersive X-ray spectroscopy. The nanocomposite undergoes a color change from yellow to colorless in presence of Hg(II), and this effect is based on the disappearance of the localized surface plasmon resonance absorption of the AgNPs due to the formation of silver-mercury amalgam. The presence of GO, on the other hand, prevents the agglomeration of the AgNPs and enhances the stability of the nanocomposite material in solution. Hence, the probe represents a viable optical probe for the determination of mercury(II) ions in that it can be used to visually detect Hg(II) concentrations as low as 100 μM. The instrumental LOD is 338 nM. (author)

  9. Hydrolytic conversion of amorphous calcium phosphate into apatite accompanied by sustained calcium and orthophosphate ions release

    Energy Technology Data Exchange (ETDEWEB)

    Niu, Xufeng, E-mail: nxf@buaa.edu.cn [Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191 (China); BUAA Research Institute, Guangzhou 510530 (China); Research Institute of Beihang University in Shenzhen, Shenzhen 518057 (China); Chen, Siqian; Tian, Feng; Wang, Lizhen [Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191 (China); Feng, Qingling [State Key Laboratory of New Ceramic and Fine Processing, Tsinghua University, Beijing 100084 (China); Fan, Yubo, E-mail: yubofan@buaa.edu.cn [Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191 (China)

    2017-01-01

    The aim of this study is to investigate the calcium and orthophosphate ions release during the transformation of amorphous calcium phosphate (ACP) to hydroxyapatite (HA) in aqueous solution. The ACP is prepared by a wet chemical method and further immersed in the distilled water for various time points till 14 d. The release of calcium and orthophosphate ions is measured with calcium and phosphate colorimetric assay kits, respectively. The transition of ACP towards HA is detected by x-ray diffraction (XRD), transmission electron microscopy (TEM), and fourier transform infrared spectroscopy (FTIR). The results indicate that the morphological conversion of ACP to HA occurs within the first 9 h, whereas the calcium and orthophosphate ions releases last for over 7 d. Such sustained calcium and orthophosphate ions release is very useful for ACP as a candidate material for hard tissue regeneration. - Highlights: • ACP is prepared using a wet chemical method. • The conversion of crystal morphology and structure occurs mainly within the initial 9 h. • The calcium and orthophosphate ions release sustains over 14 d.

  10. Application of micro beam PIXE to detection of titanium ion release from dental and orthopaedic implants

    International Nuclear Information System (INIS)

    Ektessabi, A.M.; Otsuka, T.; Tsuboi, Y.; Yokoyama, K.; Albrektsson, T.; Sennerby, L.; Johansson, C.

    1994-01-01

    In the past two decades the utilization of dental and orthopaedic implants in reconstructive surgery has been spread widely. Most of these implants are inserted in the corrosive environment of the human body for long periods of time. The level of dissolution, release, and transport of metal ions as a result of corrosion of these materials are not fully known at present. We report the results of application of micro ion beam PIXE spectroscopy to detect release of titanium from titanium and titanium alloy implants inserted in the tibiae of rabbits for three months. It was found that titanium ions could be detected in the surrounding tissues, with high precision, as a gradient from the implant surface and in higher amounts in the bone tissue as compared with the soft tissues. It is concluded that application of micro ion beam PIXE spectroscopy for detection of metal ion release, and distribution of the released material around the implants with high special resolution and accuracy may be used to further investigate the mechanism of metal release, and the relation between surface micromorphology and corrosion resistance of the implant materials. (author)

  11. Hypoxia inducible factor-1 (HIF-1)–flavin containing monooxygenase-2 (FMO-2) signaling acts in silver nanoparticles and silver ion toxicity in the nematode, Caenorhabditis elegans

    International Nuclear Information System (INIS)

    Eom, Hyun-Jeong; Ahn, Jeong-Min; Kim, Younghun; Choi, Jinhee

    2013-01-01

    In the present study, nanotoxicity mechanism associated with silver nanoparticles (AgNPs) exposure was investigated on the nematode, Caenorhabditis elegans focusing on the hypoxia response pathway. In order to test whether AgNPs-induced hypoxia inducible factor-1 (HIF-1) activation was due to hypoxia or to oxidative stress, depletion of dissolved oxygen (DO) in the test media and a rescue effect using an antioxidant were investigated, respectively. The results suggested that oxidative stress was involved in activation of the HIF-1 pathway. We then investigated the toxicological implications of HIF-1 activation by examining the HIF-1 mediated transcriptional response. Of the genes tested, increased expression of the flavin containing monooxygenase-2 (FMO-2) gene was found to be the most significant as induced by AgNPs exposure. We found that AgNPs exposure induced FMO-2 activation in a HIF-1 and p38 MAPK PMK-1 dependent manner, and oxidative stress was involved in it. We conducted all experiments to include comparison of AgNPs and AgNO 3 in order to evaluate whether any observed toxicity was due to dissolution or particle specific. The AgNPs and AgNO 3 did not produce any qualitative differences in terms of exerting toxicity in the pathways observed in this study, however, considering equal amount of silver mass, in every endpoint tested the AgNPs were found to be more toxic than AgNO 3 . These results suggest that Ag nanotoxicity is dependent not only on dissolution of Ag ion but also on particle specific effects and HIF-1–FMO-2 pathway seems to be involved in it. - Highlights: • HIF-1 signaling was investigated in C. elegans exposed to AgNPs and AgNO 3 . • HIF-1 and PMK-1 were needed for AgNPs- and AgNO 3 -induced fmo-2 gene expression. • PMK-1–HIF-1–FMO-2 pathway was dependent on oxidative stress. • AgNPs and AgNO 3 did not produce any qualitative differences in HIF-1 signaling. • AgNPs were more toxic than an equal amount of silver mass contained

  12. Hypoxia inducible factor-1 (HIF-1)–flavin containing monooxygenase-2 (FMO-2) signaling acts in silver nanoparticles and silver ion toxicity in the nematode, Caenorhabditis elegans

    Energy Technology Data Exchange (ETDEWEB)

    Eom, Hyun-Jeong; Ahn, Jeong-Min [School of Environmental Engineering and Graduate School of Energy and Environmental System Engineering, University of Seoul, 90 Jeonnong-dong, Dongdaemun-gu, Seoul 130-743 (Korea, Republic of); Kim, Younghun [Department of Chemical Engineering, Kwangwoon University, 447-1, Wolgye-dong, Nowon-gu, Seoul 139-701 (Korea, Republic of); Choi, Jinhee, E-mail: jinhchoi@uos.ac.kr [School of Environmental Engineering and Graduate School of Energy and Environmental System Engineering, University of Seoul, 90 Jeonnong-dong, Dongdaemun-gu, Seoul 130-743 (Korea, Republic of)

    2013-07-15

    In the present study, nanotoxicity mechanism associated with silver nanoparticles (AgNPs) exposure was investigated on the nematode, Caenorhabditis elegans focusing on the hypoxia response pathway. In order to test whether AgNPs-induced hypoxia inducible factor-1 (HIF-1) activation was due to hypoxia or to oxidative stress, depletion of dissolved oxygen (DO) in the test media and a rescue effect using an antioxidant were investigated, respectively. The results suggested that oxidative stress was involved in activation of the HIF-1 pathway. We then investigated the toxicological implications of HIF-1 activation by examining the HIF-1 mediated transcriptional response. Of the genes tested, increased expression of the flavin containing monooxygenase-2 (FMO-2) gene was found to be the most significant as induced by AgNPs exposure. We found that AgNPs exposure induced FMO-2 activation in a HIF-1 and p38 MAPK PMK-1 dependent manner, and oxidative stress was involved in it. We conducted all experiments to include comparison of AgNPs and AgNO{sub 3} in order to evaluate whether any observed toxicity was due to dissolution or particle specific. The AgNPs and AgNO{sub 3} did not produce any qualitative differences in terms of exerting toxicity in the pathways observed in this study, however, considering equal amount of silver mass, in every endpoint tested the AgNPs were found to be more toxic than AgNO{sub 3}. These results suggest that Ag nanotoxicity is dependent not only on dissolution of Ag ion but also on particle specific effects and HIF-1–FMO-2 pathway seems to be involved in it. - Highlights: • HIF-1 signaling was investigated in C. elegans exposed to AgNPs and AgNO{sub 3}. • HIF-1 and PMK-1 were needed for AgNPs- and AgNO{sub 3}-induced fmo-2 gene expression. • PMK-1–HIF-1–FMO-2 pathway was dependent on oxidative stress. • AgNPs and AgNO{sub 3} did not produce any qualitative differences in HIF-1 signaling. • AgNPs were more toxic than an equal

  13. Simultaneous ionization and analysis of 84 anabolic androgenic steroids in human urine using liquid chromatography-silver ion coordination ionspray/triple-quadrupole mass spectrometry.

    Science.gov (United States)

    Kim, So-Hee; Cha, Eun-Ju; Lee, Kang Mi; Kim, Ho Jun; Kwon, Oh-Seung; Lee, Jaeick

    2014-01-01

    Metal ion coordination ionspray (M(+) CIS) ionization is a powerful technique to enhance ionization efficiency and sensitivity. In this study, we developed and validated an analytical method for simultaneous ionization and analysis of 84 anabolic androgenic steroids (65 exogenous and 19 endogenous) using liquid chromatography-silver ion coordination ionspray/triple-quadrupole mass spectrometry (LC-Ag(+) CIS/MS/MS). The concentrations of silver ions and organic solvents have been optimized to increase the amount of silver ion coordinated complexes. A combination of 25 μM of silver ions and methanol showed the best sensitivity. The validation results showed the intra- (0.8-9.2%) and inter-day (2.5-14.9%) precisions, limits of detection (0.0005-5.0 ng/mL), and matrix effect (71.8-100.3%) for the screening analysis. No significant ion suppression was observed. In addition, this method was successfully applied to analysis of positive samples from suspected abusers and useful for the detection of the trace levels of anabolic steroids in human urine samples. Copyright © 2014 John Wiley & Sons, Ltd.

  14. Grazing incidence small angle X-ray scattering study of silver nanoparticles in ion-exchanged glasses

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Weidong, E-mail: 57399942@qq.com [College of Materials Science and Engineering, Qiqihar University, Qiqihar 161006 (China); Wu, Zhaojun [Department of Practice Teaching and Equipment Management, Qiqihar University, Qiqihar 161006 (China); Gu, Xiaohua [College of Materials Science and Engineering, Qiqihar University, Qiqihar 161006 (China); Xing, Xueqing; Mo, Guang [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Wu, Zhonghua, E-mail: wuzh@ihep.ac.cn [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)

    2015-05-15

    The size and distribution of silver nanoparticles in ion-exchanged silicate glass induced by thermal treatments in air at different temperatures were investigated by means of grazing incidence small angle X-ray scattering technique, X-ray diffraction and optical absorption spectra. Silver–sodium ion exchange of soda-lime silicate glasses was done at 350 °C for 240 min, then the samples were treated by thermal annealing in air at different temperatures 400, 500 and 550 °C, respectively, for 1 h. After the annealing treatment above 400 °C for 1 h, smaller Ag nanoparticles occurred, together with bigger ones. Both dissolution of smaller Ag nanoparticles and diffusion of larger ones are discussed in these stages of annealing in this contribution.

  15. Wear and corrosion behaviors of Ti6Al4V alloy biomedical materials by silver plasma immersion ion implantation process

    Energy Technology Data Exchange (ETDEWEB)

    Hongxi, Liu [School of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093 (China); Qian, Xu, E-mail: vipliuhx@yahoo.com.cn [Faculty of Adult Education, Kunming University of Science and Technology, Kunming 650051 (China); Xiaowei, Zhang; Chuanqi, Wang [School of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093 (China); Baoyin, Tang [State Key Laboratory of Advanced Welding Production Technology, Harbin Institute of Technology, Harbin 150001 (China)

    2012-10-30

    In order to improve the wear resistance and anti-corrosion behaviors of Ti6Al4V (TC4) alloy, polished samples were implanted with silver (Ag) ions by plasma immersion ion implantation (PIII) technique. The phase composition and element concentration-depth distribution in modified layer were characterized by X-ray diffraction (XRD) and Auger electron spectrum (AES). Corrosion resistance, microhardness, friction and wear behaviors of PIII-TC4 alloy changed with the Ag ion implantation dose. XRD analysis reveals that the surface modified layer consists of Ag and a small amount of TiAg phases. AES results show that Ag atomic peak concentration is 9.88%, about 14.4 nm from the surface. The maximum nanohardness and elastic modulus of PIII-TC4 alloy increases by 62.5% and 54.5%, respectively. The lowest friction coefficient reduces from 0.78 to 0.2. The test result of potentiodynamic polarization in 3.5% NaCl saturated solution indicates that the sample of Ag ion dose at 1.0 Multiplication-Sign 10{sup 17} ions/cm{sup 2} has the best corrosion resistance with the lowest corrosion current density and the least porosity.

  16. Formation of conductive and reflective silver nanolayers on plastic films via ion doping and solid–liquid interfacial reduction at ambient temperature

    International Nuclear Information System (INIS)

    Cui, Guanghui; Wu, Dezhen; Zhao, Yuan; Liu, Wei; Wu, Zhanpeng

    2013-01-01

    Conductive and reflective silver layers on both sides of polyimide films have been prepared by doping silver–ammonia ions into the surfaces of polyimide film, and subsequent solid–liquid interfacial reduction, during which double diffusion of silver ions and newly formed silver crystals occurred between the interfaces of polyimide films and the aqueous reducing surroundings. The newly formed silver nanoparticles could migrate and aggregate onto both sides of substrate films, forming continuous and compact silver layers that result in excellent conductivity, i.e. ∼0.6 and 0.5 Ω/sq on the upside and downside surfaces, respectively. The surface reflectivity could be detected up to 80% on the downside and 90% on the upside surface as well. The effects of the silver contents and reducing conditions on the morphologies and properties have been investigated comprehensively, and the two-side properties differences were discussed. A convictive relationship between the morphologies and properties has been established, providing reliable and general guidance in terms of preparation of inorganic nanoparticles on plastic substrates. This novel and simple strategy can be extended to fabricate many other metal, metal oxide and metal sulfide nanoparticles on plastic substrates, using proper oxidants or sulfions to replace the diverse reductants. The films were characterized by inductively coupled plasma, contact angle measurement, X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, atomic force microscopy, four-point probe instrument and ultraviolet spectrophotometry

  17. Economical synthesis of silver nanoparticles using leaf extract of Acalypha hispida and its application in the detection of Mn(II ions

    Directory of Open Access Journals (Sweden)

    R. Sithara

    2017-11-01

    Full Text Available This study was focused on the synthesis of silver nanoparticles using Acalypha hispida leaf extract and the characterization of the particles using UV–Vis spectroscopy, XRD, FT-IR, and TEM. The results showed the formation of silver nanoparticles, crystalline in nature, with an average size of 20–50 nm. The leaf extract components were analyzed with GC–MS and exhibited a high content of Phytol (40.52%, n-Hexadecanoic acid (9.67%, 1,2,3-Benzenetriol (7.04%, α-d-Mannofuranoside methyl (6.22%, and d-Allose (4.45%. The optimization and statistical investigation of reaction parameters were studied and maximum yield with suitable properties of silver nanoparticles was obtained at leaf extract volume (0.5 mL, the concentration of silver nitrate (1.75 mM, and reaction temperature (50 °C. The method of detecting Mn2+ ions using the colloidal silver nanoparticles was discussed. The minimum and maximum detection limit were found to be 50 and 200 µM of Mn(II ions, respectively. Thus, the obtained results encourage the use of economical synthesis of silver nanoparticles in the development of nanosensors to detect the pollutants present in industrial effluents.

  18. Nucleic acid nanomaterials: Silver-wired DNA

    Science.gov (United States)

    Auffinger, Pascal; Ennifar, Eric

    2017-10-01

    DNA double helical structures are supramolecular assemblies that are typically held together by classical Watson-Crick pairing. Now, nucleotide chelation of silver ions supports an extended silver-DNA hybrid duplex featuring an uninterrupted silver array.

  19. Comparative evaluation of metal ions release from titanium and Ti-6Al-7Nb into bio-fluids

    Directory of Open Access Journals (Sweden)

    Lori A Joseph

    2009-01-01

    Full Text Available Background: The study was designed to investigate the effects of pH, chloride ions and nature of some bio-fluids on the amount of metal ions released from titanium and TiAl 6 Nb 7 plates following incubation in actual and simulated bio-fluids over time. Methods: The amounts of released metal ions from commercially pure titanium (CpTi and TiAl 6 Nb 7 of surgical grade on immersion in 20 mL Hank′s solution of pH 4.0 or 7.0, Hank′s solution of high chloride ions concentration, Whole Blood Serum (WBS and Phosphate Buffered Saline (PBS at 37° C were determined over an incubation time of 20 weeks using atomic absorption spectrophotometry. The levels of released metal ions were compared by two-way ANOVA and Duncan′s post-hoc tests. The amounts of titanium ions released by the samples were analyzed by Pearson′s correlation. Results: TiAl 6 Nb 7 plate showed no release of Ti ions into the test solutions until after 12 weeks of incubation, while Ti ions were released from the CpTi plate from the 1 day immersion time. The re-lease of measurable amount of Al ions from TiAl 6 Nb 7 was after 12 weeks of incubation. The rate of release of Ti and Al ions from the samples increased initially with incubation time and then stabilized due to adsorption-desorption equilibrium. Conclusion: The results showed that variations in pH and chloride ions of the test media has a sig-nificant effect on the amounts of Ti ions released, while increase in chloride ions concentration sig-nificantly elevates the release of Al ions into the bio-fluids.

  20. Cloud Point Extraction and Determination of Silver Ion in Real Sample using Bis((1H-benzo[d ]imidazol-2ylmethylsulfane

    Directory of Open Access Journals (Sweden)

    Farshid Ahmadi

    2011-01-01

    Full Text Available Bis((1H-benzo[d]imidazol-2ylmethylsulfane (BHIS was used as a complexing agent in cloud point extraction for the first time and applied for selective pre-concentration of trace amounts of silver. The method is based on the extraction of silver at pH 8.0 by using non-ionic surfactant T-X114 and bis((1H-benzo[d]imidazol-2ylmethylsulfane as a chelating agent. The adopted concentrations for BHIS, Triton X-114 and HNO3, bath temperature, centrifuge rate and time were optimized. Detection limits (3SDb/m of 1.7 along with enrichment factor of 39 for silver ion was achieved. The high efficiency of cloud point extraction to carry out the determination of analytes in complex matrices was demonstrated. The proposed method was successfully applied to the ultra-trace determination of silver in real samples.

  1. In vitro percutaneous penetration and characterization of silver from silver-containing textiles

    Directory of Open Access Journals (Sweden)

    Bianco C

    2015-03-01

    chloride aggregates at sizes of up to 1 µm were identified both in the epidermis and dermis. The large size of these particles suggests that the aggregation occurred in the skin. The formation of these aggregates likely slowed down the systemic absorption of silver. Conversely, these aggregates may form a reservoir enabling prolonged release of silver ions, which might lead to local effects.Keywords: silver textile, silver release, skin

  2. Metal ion release from metallothioneins: proteolysis as an alternative to oxidation.

    Science.gov (United States)

    Peroza, Estevão A; dos Santos Cabral, Augusto; Wan, Xiaoqiong; Freisinger, Eva

    2013-09-01

    Metallothioneins (MTs) are among others involved in the cellular regulation of essential Zn(II) and Cu(I) ions. However, the high binding affinity of these proteins requires additional factors to promote metal ion release under physiological conditions. The mechanisms and efficiencies of these processes leave many open questions. We report here a comprehensive analysis of the Zn(II)-release properties of various MTs with special focus on members of the four main subfamilies of plant MTs. Zn(II) competition experiments with the metal ion chelator 4-(2-pyridylazo)resorcinol (PAR) in the presence of the cellular redox pair glutathione (GSH)/glutathione disulfide (GSSG) show that plant MTs from the subfamilies MT1, MT2, and MT3 are remarkably more affected by oxidative stress than those from the Ec subfamily and the well-characterized human MT2 form. In addition, we evaluated proteolytic digestion with trypsin and proteinase K as an alternative mechanism for selective promotion of metal ion release from MTs. Also here the observed percentage of liberated metal ions depends strongly on the MT form evaluated. Closer evaluation of the data additionally allowed deducing the thermodynamic and kinetic properties of the Zn(II) release processes. The Cu(I)-form of chickpea MT2 was used to exemplify that both oxidation and proteolysis are also effective ways to increase the transfer of copper ions to other molecules. Zn(II) release experiments with the individual metal-binding domains of Ec-1 from wheat grain reveal distinct differences from the full-length protein. This triggers the question about the roles of the long cysteine-free peptide stretches typical for plant MTs.

  3. Effect of silver ion-induced disorder on morphological, chemical and optical properties of poly (methyl methacrylate)

    Energy Technology Data Exchange (ETDEWEB)

    Arif, Shafaq, E-mail: sarif2005@gmail.com [Department of Physics, Lahore College for Women University, Lahore 54000 (Pakistan); Saleemi, Farhat [Department of Physics, Lahore College for Women University, Lahore 54000 (Pakistan); Rafique, M. Shahid [Department of Physics, University of Engineering & Technology, Lahore 54000 (Pakistan); Naab, Fabian; Toader, Ovidiu [Department of Nuclear Engineering and Radiological Sciences, Michigan Ion Beam Laboratory, University of Michigan, MI 48109-2104 (United States); Mahmood, Arshad; Aziz, Uzma [National Institute of Lasers & Optronics (NILOP), P.O. Nilore, Islamabad (Pakistan)

    2016-11-15

    Ion implantation is a versatile technique to tailor the surface properties of polymers in a controlled manner. In the present study, samples of poly (methyl methacrylate) (PMMA) have been implanted with 400 keV silver (Ag{sup +}) ion beam to various ion fluences ranging from 5 × 10{sup 13} to 5 × 10{sup 15} ions/cm{sup 2}. The effect of Ag{sup +} ion-induced disorder on morphological, chemical and optical properties of PMMA is analyzed using Atomic Force Microscope (AFM), Fourier transform infrared spectroscopy (FTIR) and ultraviolet–visible (UV–Vis) spectroscopy. Furthermore, the electrical conductivity of pristine and implanted PMMA is measured using four probe apparatus. The AFM images revealed the growth of nano-sized grainy structures and hillocks above the surface of implanted PMMA. The FTIR spectra confirmed the modifications in chemical structure of PMMA along with the formation of −C=C− carbon contents. The refractive index, extinction coefficient and photoconductivity of implanted PMMA have been found to increase as a function of ion fluence. Simultaneously, indirect optical band gap is reduced from 3.13 to 0.81 eV at a relatively high fluence (5 × 10{sup 15} ions/cm{sup 2}). A linear correlation has been established between the band gap and Urbach energies. Moreover, the electrical conductivity of Ag{sup +} implanted PMMA has increased from 2.14 × 10{sup −10} (pristine) to 9.6 × 10{sup −6} S/cm.

  4. Ion beam analysis and AMS dating of the silver coin hoard of Preuschdorf (Alsace, France)

    Science.gov (United States)

    Beck, Lucile; Alloin, Elise; Vigneron, Anaïs; Caffy, Ingrid; Klein, Ulrich

    2017-09-01

    The hoard of Preuschdorf is a monetary deposit discovered in Alsace (France) in 2005. This find was composed of 7327 silver-copper coins. They seem to have been struck over more than one century, between the end of the 15th and the beginning of the 17th century. This hoard is an exceptional find composed of a large quantity of coins from various periods, areas and contexts. It is also remarkable by the presence of counterfeit coins. IBA was used to analyze the silver content of the official coins by combining PIXE and RBS. The fineness was found to be between 20 and 42% according to the mint place and an unexpected subdivision of the values has been revealed. For the counterfeit coins, the analyses were able to bring to light different elaboration processes: amalgam silvering with two various contents of mercury and application of a thin layer of pure silver. Finally, linen fibers attached to the coins have been dated by AMS radiocarbon dating. The radiocarbon calibrated dates perfectly match with the chronological range given by the coins.

  5. Effects of silver nanoparticles and ions and interactions with first line of defense

    NARCIS (Netherlands)

    Georgantzopoulou, A.

    2015-01-01

    Summary

    Silver nanoparticles (Ag NPs) are among the most promising groups of NPs (particles with all dimensions below 100 nm) for application in numerous consumer products due to their broad spectrum antimicrobial activities. Examples are incorporation in textiles and

  6. Conducting composites prepared by the reduction of silver ions with poly(p-phenylenediamine)

    Czech Academy of Sciences Publication Activity Database

    Magdziarz, Przemyslaw; Bober, Patrycja; Trchová, Miroslava; Morávková, Zuzana; Bláha, Michal; Prokeš, J.; Stejskal, Jaroslav

    2015-01-01

    Roč. 64, č. 4 (2015), s. 496-504 ISSN 0959-8103 R&D Projects: GA ČR(CZ) GP14-05568P Institutional support: RVO:61389013 Keywords : poly(p-phenylenediamine) * p-phenylenediamine * silver Subject RIV: JI - Composite Materials Impact factor: 2.414, year: 2015

  7. Silver nanoparticles in aquatic environments: Physiochemical behavior and antimicrobial mechanisms.

    Science.gov (United States)

    Zhang, Chiqian; Hu, Zhiqiang; Deng, Baolin

    2016-01-01

    Nanosilver (silver nanoparticles or AgNPs) has unique physiochemical properties and strong antimicrobial activities. This paper provides a comprehensive review of the physicochemical behavior (e.g., dissolution and aggregation) and antimicrobial mechanisms of nanosilver in aquatic environments. The inconsistency in calculating the Gibbs free energy of formation of nanosilver [ΔGf(AgNPs)] in aquatic environments highlights the research needed to carefully determine the thermodynamic stability of nanosilver. The dissolutive release of silver ion (Ag(+)) in the literature is often described using a pseudo-first-order kinetics, but the fit is generally poor. This paper proposes a two-stage model that could better predict silver ion release kinetics. The theoretical analysis suggests that nanosilver dissolution could occur under anoxic conditions and that nanosilver may be sulfidized to form silver sulfide (Ag2S) under strict anaerobic conditions, but more investigation with carefully-designed experiments is required to confirm the analysis. Although silver ion release is likely the main antimicrobial mechanism of nanosilver, the contributions of (ion-free) AgNPs and reactive oxygen species (ROS) generation to the overall toxicity of nanosilver must not be neglected. Several research directions are proposed to better understand the dissolution kinetics of nanosilver and its antimicrobial mechanisms under various aquatic environmental conditions. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Silver as antibacterial towards Listeria monocytogenes

    Directory of Open Access Journals (Sweden)

    Simone eBelluco

    2016-03-01

    Full Text Available Listeria monocytogenes is a serious foodborne pathogen that can contaminate food during processing and can grow during food shelf-life. New types of safe and effective food contact materials embedding antimicrobial agents, like silver, can play an important role in the food industry. The present work aimed at evaluating the in vitro growth kinetics of different strains of L. monocytogenes in the presence of silver, both in its ionic and nano form. The antimicrobial effect was determined by assaying the number of culturable bacterial cells, which formed colonies after incubation in the presence of silver nanoparticles (AgNPs or silver nitrate (AgNO3. Ionic release experiments were performed in parallel. A different reduction of bacterial viability between silver ionic and nano forms was observed, with a time delayed effect exerted by AgNPs. An association between antimicrobial activity and ions concentration was shown by both silver chemical forms, suggesting the major role of ions in the antimicrobial mode of action.

  9. Release of proteins via ion exchange from albumin-heparin microspheres

    NARCIS (Netherlands)

    Kwon, Glen S.; Bae, You Han; Cremers, H.F.M.; Cremers, Harry; Feijen, Jan; Kim, Sung Wan

    1992-01-01

    Albumin-heparin and albumin microspheres were prepared as ion exchange gels for the controlled release of positively charged polypeptides and proteins. The adsorption isotherms of chicken egg and human lysozyme, as model proteins, on microspheres were obtained. An adsorption isotherm of chicken egg

  10. Release of metal ions from round and rectangular NiTi wires

    Directory of Open Access Journals (Sweden)

    Arash Azizi

    2016-04-01

    Full Text Available Abstract Background The aim of this study was to evaluate the amount of nickel and titanium ions released from two wires with different shapes and a similar surface area. Methods Forty round nickel-titanium (NiTi arch wires with the diameter of 0.020 in. and 40 rectangular NiTi arch wires with the diameter of 0.016 × 0.016 in. were immersed in artificial saliva during a 21-day period. The surface area of both wires was 0.44 in.2. Wires were separately dipped into polypropylene tubes containing 50 ml of buffer solution and were incubated and maintained at 37 °C. Inductively coupled plasma atomic emission spectrometry (ICP-AES was used to measure the amount of ions released after exposure lengths of 1 h, 24 h, 1 week, and 3 weeks. Repeated measures ANOVA and Tukey tests were used to evaluate the data. Results The results indicated that the amount of nickel and titanium concentrations was significantly higher in the rectangular wire group. The most significant release of all metals was measured after the first hour of immersion. In the rectangular wire group, 243 ± 4.2 ng/ml of nickel was released after 1 h, while 221.4 ± 1.7 ng/ml of nickel was released in the round wire group. Similarly, 243.3 ± 2.8 ng/ml of titanium was released in the rectangular wire group and a significantly lower amount of 211.9 ± 2.3 ng/ml of titanium was released in the round wire group. Conclusions Release of metal ions was influenced by the shape of the wire and increase of time.

  11. Antibacterial Behavior of Additively Manufactured Porous Titanium with Nanotubular Surfaces Releasing Silver Ions

    NARCIS (Netherlands)

    Amin Yavari, S.; Loozen, L.; Paganelli, F. L.; Bakhshandeh, S.; Lietaert, K.; Groot, J. A.; Fluit, A. C.; Boel, C. H E; Alblas, J.; Vogely, H. C.; Weinans, H.; Zadpoor, A. A.

    2016-01-01

    Additive manufacturing (3D printing) has enabled fabrication of geometrically complex and fully interconnected porous biomaterials with huge surface areas that could be used for biofunctionalization to achieve multifunctional biomaterials. Covering the huge surface area of such porous titanium with

  12. The effect of hydrogen peroxide concentration on metal ion release from dental casting alloys.

    Science.gov (United States)

    Al-Salehi, S K; Hatton, P V; Johnson, A; Cox, A G; McLeod, C

    2008-04-01

    There are concerns that tooth bleaching agents may adversely affect dental materials. The aim of this study was to test the hypothesis that increasing concentrations of hydrogen peroxide (HP) are more effective than water at increasing metal ion release from two typical dental casting alloys during bleaching. Discs (n = 28 for each alloy) were prepared by casting and heat treated to simulate a typical porcelain-firing cycle. Discs (n = 7) of each alloy were immersed in either 0%, 3%, 10% or 30% (w/v) HP solutions for 24 h at 37 degrees C. Samples were taken for metal ion release determination using inductively coupled plasma-mass spectrometry and the data analysed using a two-way anova followed by a one-way anova. The surface roughness of each disc was measured using a Talysurf contact profilometer before and after bleaching and the data analysed using a paired t-test. With the exception of gold, the differences in metal ion concentration after treatment with 0% (control) and each of 3%, 10% and 30% HP (w/v) were statistically significant (P alloys increased with increasing HP concentrations (over 3000% increase in Ni and 1400% increase in Pd ions were recorded when HP concentration increased from 0% to 30%). Surface roughness values of the samples before and after bleaching were not significantly different (P > 0.05) Exposure of the two dental casting alloys to HP solutions increased metal ion release of all the elements except gold.

  13. 2-Alkylcyclobutanones as markers for irradiated foodstuffs. III. Improvement of the field of application on the EN 1785 method by using silver ion chromatography

    NARCIS (Netherlands)

    Ndiaye, B; Horvatovich, P; Miesch, M; Hasselmann, C; Marchioni, E

    1999-01-01

    The inclusion of a purification step by silver ion chromatography in the EN 1785 analytical protocol for 2-alkylcyclobutanones (validated by the European Committee for Standardization for the detection of ionizing radiation treatment) has considerably improved the quality of the chromatograms

  14. Regioisomeric analysis of triacylglycerols using silver-ion liquid chromatography-atmospheric pressure chemical ionization mass spectrometry: Comparison of five different mass analyzers

    Czech Academy of Sciences Publication Activity Database

    Holčapek, M.; Dvořáková, H.; Lísa, M.; Girón, A. J.; Sandra, P.; Cvačka, Josef

    2010-01-01

    Roč. 1217, č. 52 (2010), s. 8186-8194 ISSN 0021-9673 R&D Projects: GA ČR GA203/09/0139 Institutional research plan: CEZ:AV0Z40550506 Keywords : triacylglycerols * silver-ion liquid chromatography * regioisomer * HPLC/MS * APCI Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 4.194, year: 2010

  15. Development of a 3D origami multiplex electrochemical immunodevice using a nanoporous silver-paper electrode and metal ion functionalized nanoporous gold-chitosan.

    Science.gov (United States)

    Li, Weiping; Li, Long; Li, Meng; Yu, Jinghua; Ge, Shenguang; Yan, Mei; Song, Xianrang

    2013-10-25

    A simple and sensitive 3D microfluidic origami multiplex electrochemical immunodevice was developed for the first time using a novel nanoporous silver modified paper working electrode as a sensor platform and different metal ion functionalized nanoporous gold-chitosan as a tracer.

  16. Ion release from magnesium materials in physiological solutions under different oxygen tensions.

    Science.gov (United States)

    Feyerabend, Frank; Drücker, Heiko; Laipple, Daniel; Vogt, Carla; Stekker, Michael; Hort, Norbert; Willumeit, Regine

    2012-01-01

    Although magnesium as degradable biomaterial already showed clinical proof of concepts, the design of new alloys requires predictive in vitro methods, which are still lacking. Incubation under cell culture conditions to obtain "physiological" corrosion may be a solution. The aim of this study was to analyse the influence of different solutions, addition of proteins and of oxygen availability on the corrosion of different magnesium materials (pure Mg, WE43, and E11) with different surface finishing. Oxygen content in solution, pH, osmolality and ion release were determined. Corrosion led to a reduction of oxygen in solution. The influence of oxygen on pH was enhanced by proteins, while osmolality was not influenced. Magnesium ion release was solution-dependent and enhanced in the initial phase by proteins with delayed release of alloying elements. The main corrosion product formed was magnesium carbonate. Therefore, cell culture conditions are proposed as first step toward physiological corrosion.

  17. Point-of-Use Removal of Cryptosporidium parvum from Water: Independent Effects of Disinfection by Silver Nanoparticles and Silver Ions and by Physical Filtration in Ceramic Porous Media.

    Science.gov (United States)

    Abebe, Lydia S; Su, Yi-Hsuan; Guerrant, Richard L; Swami, Nathan S; Smith, James A

    2015-11-03

    Ceramic water filters (CWFs) impregnated with silver nanoparticles are a means of household-level water treatment. CWFs remove/deactivate microbial pathogens by employing two mechanisms: metallic disinfection and physical filtration. Herein we report on the independent effects of silver salt and nanoparticles on Cryptosporidium parvum and the removal of C. parvum by physical filtration in porous ceramic filter media. Using a murine (mouse) model, we observed that treatment of oocysts with silver nitrate and proteinate-capped silver nanoparticles resulted in decreased infection relative to untreated oocysts. Microscopy and excystation experiments were conducted to support the disinfection investigation. Heat and proteinate-capped silver-nanoparticle treatment of oocysts resulted in morphological modifications and decreased excystation rates of sporozoites. Subsequently, disk-shaped ceramic filters were produced to investigate the transport of C. parvum. Two factors were varied: sawdust size and clay-to-sawdust ratio. Five disks were prepared with combinations of 10, 16, and 20 mesh sawdust and sawdust percentage that ranged from 9 to 11%. C. parvum removal efficiencies ranged from 1.5 log (96.4%) to 2.1 log (99.2%). The 16-mesh/10% sawdust had the greatest mean reduction of 2.1-log (99.2%), though there was no statistically significant difference in removal efficiency. Based on our findings, physical filtration and silver nanoparticle disinfection likely contribute to treatment of C. parvum for silver impregnated ceramic water filters, although the contribution of physical filtration is likely greater than silver disinfection.

  18. Analysis of molecular species of triacylglycerols from vegetable oils containing fatty acids with non-methylene-interrupted double bonds, by HPLC in the silver-ion mode

    Energy Technology Data Exchange (ETDEWEB)

    Joh, Y.; Kim, S. [Dong A Univ., Pusan (Korea, Republic of)

    1998-10-20

    The possibilities for application of silver ion HPLC to analysis of the triacylglycerols containing conjugate trienoic acids and {Delta}{sup 5}-polymethylene-interrupted acids and proportions of triacylglycerol fractions obtained by silver-ion HPLC from the seed oil of Momordica charantia double bonds were examined, respectively. The triacylglycerols of seed oils containing conjugate trienoic acids such as {alpha}-eleostearic acid (C{sub 18:3 9c,11t,13t}) and punicic acid (C{sub 18:3} {sub 9c,11t,13c}) were resolved by silver-ion HPLC. Fractions were fractionated on the basis of the number and configuration of double bonds in the species, and the elution profile is quite different from that of the species comprising exclusively saturated and unsaturated fatty acids with methylene-interrupted double bonds ; for instance, the species (DT(c2)) composed of one dienoic acid and two conjugate trienoic acids eluted much earlier than the species (D{sub 2}T{sub c}) composed of two dienoic acids and one conjugate trienoic acid, in spite of having larger number of double bonds. This means that the interaction of conjugate double bonds with silver ions is weaker than that of methylene-interrupted double bonds, presumably because of the delocalization of {pi}-electrons in conjugate double bonds. In this instance, the strength of interaction of a conjugate trienoic double bond system with silver ions seemed to be between that of methylene-interrupted dienoic and monoenoic double bond systems. Triacylglycerols of the seeds of Ginkgo biloba have been resolved by HPLC in the silver-ion mode according to the number and position of double bonds. In this instance, the strength of interaction between the {pi}-electrons of double bonds in the fatty acyl residues and silver ions is in the order; C{sub 18:3{omega}3}>C(20:3){Delta}{sup 5,11,14}C{sub 18:3}{Delta}{sup 5,9,12}>= C{sub 18:2{omega}6}>C{sub 18:2}{Delta}{sup 5,9}>C{sub 18:1{omega}9}>C{sub 18:1ome= ga7}. 49 refs., 2 figs., 2 tabs.

  19. Biosynthesis of silver nanoparticle and its application in cell wall disruption to release carbohydrate and lipid from C. vulgaris for biofuel production

    Directory of Open Access Journals (Sweden)

    Sirajunnisa Abdul Razack

    2016-09-01

    Full Text Available Microalgae are the fledging feedstocks yielding raw materials for the production of third generation biofuel. Assorted and conventional cell wall disruption techniques were helpful in extracting lipids and carbohydrates, nevertheless the disadvantages have led the biotechnologists to explore new process to lyse cell wall in a faster and an economical manner. Silver nanoparticles have the ability to break the cell wall of microalgae and release biomolecules effectively. Green synthesis of silver nanoparticles was performed using a novel bacterial isolate of Bacillus subtilis. Characterisation of nanosilver and its effect on cell wall lysis of microalgae were extensively analysed. Cell wall damage was confirmed by lactate dehydrogenase assay and visually by SEM analysis. This first piece of research work on direct use of nanoparticles for cell wall lysis would potentially be advantageous over its conventional approaches and a greener, cost effective and non laborious method for the production of biodiesel.

  20. Energy spectra of gold and silver ions jointly expanding in multielement laser plasma

    International Nuclear Information System (INIS)

    Bedilov, M.R.; Kuramatov, D.; Tsoj, T.G.; Kholbaev, A.; Khaitbaev, K.

    1986-01-01

    The results of the investigations on energy distribution of Au and Ag ions jointly expanding in multielement paser plasma are presented. It is denonstrated, that on the stages of formation and expanding of multielement plasma multucharged ions considerable contribution is made by collision processes between electrons and ions and between ions of light and heavy elements. The results are discussed on the basis of existing theoretical models

  1. Temperature, pressure, and density of electron, atom and ion, in the breaking arc of silver-cadmium contacts used in medium current region

    International Nuclear Information System (INIS)

    Aida, Teizo

    1979-01-01

    Wear of silver-cadmium contacts at the time of breaking was studied. The materials of the contacts were silver-cadmium alloy and silver-cadmium oxide sinter. The spectra of arc discharge generated at the time of breaking contact were analyzed with a monochromator photo multiplier. The ratio of the densities of cadmium and silver atoms in the arc can be estimated from the observed intensities of spectrum lines. The electron density is obtained from the arc current density. The proportion of the cadmium atoms in the arc was about 30 percent. The densities of silver atoms and cadmium atoms can be estimated by the principle of thermal ionization equilibrium. The ion densities were also estimated. The partial pressures of silver and cadmium atoms in the arc can be obtained from the Boyle-Charles' law. A formula which gives the number of atoms liberated from the surfaces of contacts at the time of breaking was given by Boddy et al. (Kato, T.)

  2. Antibacterial activity and ion release of bonding agent containing amorphous calcium phosphate nanoparticles.

    Science.gov (United States)

    Chen, Chen; Weir, Michael D; Cheng, Lei; Lin, Nancy J; Lin-Gibson, Sheng; Chow, Laurence C; Zhou, Xuedong; Xu, Hockin H K

    2014-08-01

    Recurrent caries at the margins is a primary reason for restoration failure. The objectives of this study were to develop bonding agent with the double benefits of antibacterial and remineralizing capabilities, to investigate the effects of NACP filler level and solution pH on Ca and P ion release from adhesive, and to examine the antibacterial and dentin bond properties. Nanoparticles of amorphous calcium phosphate (NACP) and a quaternary ammonium monomer (dimethylaminododecyl methacrylate, DMADDM) were synthesized. Scotchbond Multi-Purpose (SBMP) primer and adhesive served as control. DMADDM was incorporated into primer and adhesive at 5% by mass. NACP was incorporated into adhesive at filler mass fractions of 10%, 20%, 30% and 40%. A dental plaque microcosm biofilm model was used to test the antibacterial bonding agents. Calcium (Ca) and phosphate (P) ion releases from the cured adhesive samples were measured vs. filler level and solution pH of 7, 5.5 and 4. Adding 5% DMADDM and 10-40% NACP into bonding agent, and water-aging for 28 days, did not affect dentin bond strength, compared to SBMP control at 1 day (p>0.1). Adding DMADDM into bonding agent substantially decreased the biofilm metabolic activity and lactic acid production. Total microorganisms, total streptococci, and mutans streptococci were greatly reduced for bonding agents containing DMADDM. Increasing NACP filler level from 10% to 40% in adhesive increased the Ca and P ion release by an order of magnitude. Decreasing solution pH from 7 to 4 increased the ion release from adhesive by 6-10 folds. Bonding agents containing antibacterial DMADDM and remineralizer NACP were formulated to have Ca and P ion release, which increased with NACP filler level from 10% to 40% in adhesive. NACP adhesive was "smart" and dramatically increased the ion release at cariogenic pH 4, when these ions would be most-needed to inhibit caries. Therefore, bonding agent containing DMADDM and NACP may be promising to inhibit

  3. Behavior of silver nanoparticles and ions in food simulants and low fat cow milk under migration conditions

    DEFF Research Database (Denmark)

    Jokar, Maryam; Correia, Manuel; Löschner, Katrin

    2018-01-01

    , 50% ethanol preserved the AgNPs, while acetic acid induced dissolution of AgNPs. Dissolution of the PEG-AgNPs obeyed pseudo-first-order reaction kinetics. PEG-AgNPs showed similar behavior in low fat cow milk during storage at 4 °C for 5 days as in the corresponding food simulant, 50% ethanol....... Addition of sodium chloride to ultrapure water led to enhanced dissolution. The potential reduction of silver ions to NPs in food simulants, low fat milk and in alkaline conditions in the presence of reducing agents was studied. Based on the obtained results, it is unlikely that AgNPs are formed from Ag...

  4. Spectrophotometric determination of L-cysteine by using polyvinylpyrrolidone-stabilized silver nanoparticles in the presence of barium ions

    Science.gov (United States)

    Bamdad, Farzad; Khorram, Fateme; Samet, Maryam; Bamdad, Kourosh; Sangi, Mohammad Reza; Allahbakhshi, Fateme

    2016-05-01

    In this article a simple and selective colorimetric probe for cysteine determination using silver nano particles (AgNPS) is described. The determination process was based upon the surface plasmon resonance properties of polyvinylpyrrolidone-stabilized AgNPS. Interaction of AgNPS with cysteine molecules in the presence of barium ions induced a red shift in the surface plasmon resonance (SPR) maximum of AgNPs, as a result of nanoparticle aggregation. Consequently, yellow color of AgNP solution was changed to pink. The linear range for the determination of cysteine was 3.2-8.2 μM (R = 0.9965) with a limit of detection equal to 2.8 μM (3σ). The proposed method was successfully applied to the determination of cysteine in human plasma samples. Acceptable recovery results of the spiked samples confirmed the validity of the proposed method.

  5. Spectrophotometric determination of L-cysteine by using polyvinylpyrrolidone-stabilized silver nanoparticles in the presence of barium ions.

    Science.gov (United States)

    Bamdad, Farzad; Khorram, Fateme; Samet, Maryam; Bamdad, Kourosh; Sangi, Mohammad Reza; Allahbakhshi, Fateme

    2016-05-15

    In this article a simple and selective colorimetric probe for cysteine determination using silver nano particles (AgNPS) is described. The determination process was based upon the surface plasmon resonance properties of polyvinylpyrrolidone-stabilized AgNPS. Interaction of AgNPS with cysteine molecules in the presence of barium ions induced a red shift in the surface plasmon resonance (SPR) maximum of AgNPs, as a result of nanoparticle aggregation. Consequently, yellow color of AgNP solution was changed to pink. The linear range for the determination of cysteine was 3.2-8.2 μM (R=0.9965) with a limit of detection equal to 2.8 μM (3σ). The proposed method was successfully applied to the determination of cysteine in human plasma samples. Acceptable recovery results of the spiked samples confirmed the validity of the proposed method. Copyright © 2016 Elsevier B.V. All rights reserved.

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

    International Nuclear Information System (INIS)

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

    2016-01-01

    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. - Highlights: • Silver nanocoatings were deposited on urinary catheters. • Both luminal and outer surface were successfully treated. • The treated devices demonstrated were effective against different microorganisms. • The antibacterial potential of the devices was assessed.

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

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, Ian Richard [School of Pharmacy & Biomolecular Sciences, University of Brighton, Lewes Road, Brighton BN2 4GJ (United Kingdom); Pollini, Mauro, E-mail: mauro.pollini@unisalento.it [Department of Engineering for Innovation, University of Salento, Via Monteroni, 73100 Lecce (Italy); Silvertech Ltd, Via Monteroni, 73100 Lecce (Italy); Paladini, Federica [Department of Engineering for Innovation, University of Salento, Via Monteroni, 73100 Lecce (Italy)

    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. - Highlights: • Silver nanocoatings were deposited on urinary catheters. • Both luminal and outer surface were successfully treated. • The treated devices demonstrated were effective against different microorganisms. • The antibacterial potential of the devices was assessed.

  8. Effect of 100 MeV swift heavy ions [silver (Ag8+)] on morphological and electrical properties of polypyrrole

    Science.gov (United States)

    Kaur, Amarjeet; Dhillon, Anju; Avasthi, D. K.

    2009-10-01

    Polypyrrole (PPY) films were prepared by the electrochemical polymerization technique. The fully undoped samples were irradiated with different fluences ranging from 1010 to 1012 ions/cm2 of 100 MeV silver (Ag8+) ions. In order to explain the effect of these radiations, a comparative study of samples before and after irradiation was performed by using various techniques such as surface electron microscopy, atomic force microscopy, and X-ray diffraction. With an increase in fluence, the surface structure of PPY films becomes smoother, and the conductivity increases by two orders, which has been explained in light of reordering of polymer chains. The temperature dependence of the dc conductivity of irradiated as well as unirradiated samples has been investigated at 77-300 K. The charge transport properties before and after irradiation are retained although conductivity increases. It has been proposed that swift heavy ion irradiation affects the interchain conductivity. The conductivity of irradiated samples is stable under atmospheric conditions for more than 9 months. The present investigations open up the scope for the applicability of irradiated conducting polymers as microstructures with defined conductivity for sensor applications.

  9. Effect of 100 MeV swift heavy ions [silver (Ag8+)] on morphological and electrical properties of polypyrrole

    International Nuclear Information System (INIS)

    Kaur, Amarjeet; Dhillon, Anju; Avasthi, D. K.

    2009-01-01

    Polypyrrole (PPY) films were prepared by the electrochemical polymerization technique. The fully undoped samples were irradiated with different fluences ranging from 10 10 to 10 12 ions/cm 2 of 100 MeV silver (Ag 8+ ) ions. In order to explain the effect of these radiations, a comparative study of samples before and after irradiation was performed by using various techniques such as surface electron microscopy, atomic force microscopy, and X-ray diffraction. With an increase in fluence, the surface structure of PPY films becomes smoother, and the conductivity increases by two orders, which has been explained in light of reordering of polymer chains. The temperature dependence of the dc conductivity of irradiated as well as unirradiated samples has been investigated at 77-300 K. The charge transport properties before and after irradiation are retained although conductivity increases. It has been proposed that swift heavy ion irradiation affects the interchain conductivity. The conductivity of irradiated samples is stable under atmospheric conditions for more than 9 months. The present investigations open up the scope for the applicability of irradiated conducting polymers as microstructures with defined conductivity for sensor applications.

  10. Femtosecond Laser-Induced Formation of Gold-Rich Nanoalloys from the Aqueous Mixture of Gold-Silver Ions

    Directory of Open Access Journals (Sweden)

    Yuliati Herbani

    2010-01-01

    Full Text Available The synthesis of gold-silver (AuAg nanoalloys of various compositions has been performed by direct irradiation of highly intense femtosecond laser pulse in the presence of polyvinylpyrrolidone (PVP. The mixture of Au and Ag ions of low concentration was simply introduced into a glass vial and subjected to femtosecond laser pulses for several minutes. The AuAg nanoalloys of 2-3 nm with reasonably narrow size distribution were formed, and the position of the surface plasmon resonance (SPR increased monotonically with an increase in the gold molar fraction in the ion solutions. The high resolution transmission electron microscope (HRTEM images exhibited the absence of core-shell structures, and the energy dispersive X-ray spectroscopy (EDX analysis confirmed that the particles were Au-rich alloys even for the samples with large fraction of Ag+ ions fed in the solution mixture. The formation mechanism of the alloy nanoparticles in the high intensity optical field was also discussed.

  11. Release of metal ions from fixed orthodontic appliance: an in vitro study in continuous flow system.

    Science.gov (United States)

    Mikulewicz, Marcin; Chojnacka, Katarzyna; Wołowiec, Paulina

    2014-01-01

    To evaluate the release of metal ions from fixed orthodontic appliances. A new system for in vitro testing of dental materials was constructed and consisted of a thermostatic glass reactor that enabled immersion of the studied material. Experimental conditions reflected the human oral cavity, with a temperature of 37°C and a saliva flow rate of 0.5mL/min. The simulated fixed orthodontic appliance made of stainless steel was evaluated. Sampling was performed at several time points during the 28-day study, and the metal ion concentration was determined by inductively coupled plasma optical emission spectrometry. The total mass of released metal ions from the appliance during 4 weeks of the experiment was as follows nickel 18.7 μg, chromium 5.47 μg, copper 31.3 μg. The estimated doses of nickel, chromium, and copper determined by extrapolation of experimental data released during the treatment period were far below the toxic dose to humans. This shows that orthodontic treatment might not be a significant source of exposure to these metal ions.

  12. Ion Release and Galvanic Corrosion of Different Orthodontic Brackets and Wires in Artificial Saliva.

    Science.gov (United States)

    Tahmasbi, Soodeh; Sheikh, Tahereh; Hemmati, Yasamin B

    2017-03-01

    To investigate the galvanic corrosion of brackets manufactured by four different companies coupled with stainless steel (SS) or nickel-titanium (NiTi) wires in an artificial saliva solution. A total of 24 mandibular central incisor Roth brackets of four different manufacturers (American Orthodontics, Dentaurum, Shinye, ORJ) were used in this experimental study. These brackets were immersed in artificial saliva along with SS or NiTi orthodontic wires (0.016'', round) for 28 days. The electric potential difference of each bracket/ wire coupled with a saturated calomel reference electrode was measured via a voltmeter and recorded constantly. Corrosion rate (CR) was calculated, and release of ions was measured with an atomic absorption spectrometer. Stereomicroscope was used to evaluate all samples. Then, samples with corrosion were further assessed by scanning electron microscope and energy-dispersive X-ray spectroscopy. Two-way analysis of variance was used to analyze data. Among ions evaluated, release of nickel ions from Shinye brackets was significantly higher than that of other brackets. The mean potential difference was significantly lower in specimens containing a couple of Shinye brackets and SS wire compared with other specimens. No significant difference was observed in the mean CR of various groups (p > 0.05). Microscopic evaluation showed corrosion in two samples only: Shinye bracket coupled with SS wire and American Orthodontics bracket coupled with NiTi wire. Shinye brackets coupled with SS wire showed more susceptibility to galvanic corrosion. There were no significant differences among specimens in terms of the CR or released ions except the release of Ni ions, which was higher in Shinye brackets.

  13. Wound healing effect of bioactive ion released from Mg-smectite.

    Science.gov (United States)

    Sasaki, Yu; Sathi, Gulsan Ara; Yamamoto, Osamu

    2017-08-01

    Bioactive ions like Mg 2+ and Si 4+ have been known as promotion factors of tissue regeneration. In the present work, Mg-smectite, consisting of Mg 2+ and Si 4+ ions, was synthesized by a solution process, and evaluated for the efficiency of the powder on wound healing in rats. White precipitates were obtained by mixing a magnesium chloride hexahydrate solution and a sodium silicate hexahydrate solution at room temperature. The precipitates mixed with a NaOH aqueous solution were subjected to hydrothermal reaction, and finally crystalline Mg-smectite powder was obtained. The crystal and molecular structure of Mg-smectite was identified by X-ray diffractometry (XRD) and Fourier-transform infrared spectroscopy (FT-IR). The synthesized material was determined to be crystalline Mg-smectite. The amount of Mg 2+ and Si 4+ ions released from Mg-smectite in physiological saline was analyzed by inductively coupled plasma mass spectroscopy (ICP-MS). The total amount of Si 4+ ion released from Mg-smectite was greater than that of Mg 2+ ion. To evaluate the wound healing effect of Mg-smectite, Mg-smectite powder was applied to a full-thickness surgical wound reaching the subcutaneous tissue in the rat's abdomen. At 1 and 2weeks, skin tissue was collected and subjected to histological analysis. The results for skin regeneration showed no significant difference in wound size between the control and Mg-smectite group. However, it was found that the neovascularization, collagen deposition, and maturation were notedly accelerated by applying Mg-smectite powder in comparison with the control. Mg-smectite can then be hypothesized to stimulate the regeneration of skin tissue by releasing Mg 2+ and Si 4+ ions. These results suggested that Mg-smectite could offer great potential as a wound dressing material. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. CORONAL SOURCES, ELEMENTAL FRACTIONATION, AND RELEASE MECHANISMS OF HEAVY ION DROPOUTS IN THE SOLAR WIND

    Energy Technology Data Exchange (ETDEWEB)

    Weberg, Micah J. [PhD Candidate in Space Science, Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, 2134A Space Research Building, 2455 Hayward Street, Ann Arbor, MI 48109-2143, USA. (United States); Lepri, Susan T. [Associate Professor, Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, 2429 Space Research Building, 2455 Hayward Street, Ann Arbor, MI 48109-2143, USA. (United States); Zurbuchen, Thomas H., E-mail: mjweberg@umich.edu, E-mail: slepri@umich.edu, E-mail: thomasz@umich.edu [Professor, Space Science and Aerospace Engineering, Associate Dean for Entrepreneurship Senior Counselor of Entrepreneurship Education, Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, 2431 Space Research Building, 2455 Hayward Street, Ann Arbor, MI 48109-2143, USA. (United States)

    2015-03-10

    The elemental abundances of heavy ions (masses larger than He) in the solar wind provide information about physical processes occurring in the corona. Additionally, the charge state distributions of these heavy ions are sensitive to the temperature profiles of their respective source regions in the corona. Heavy ion dropouts are a relatively new class of solar wind events identified by both elemental and ionic charge state distributions. We have shown that their origins lie in large, closed coronal loops where processes such as gravitational settling dominate and can cause a mass-dependent fractionation pattern. In this study we consider and attempt to answer three fundamental questions concerning heavy ion dropouts: (1) 'where are the source loops located in the large-scale corona?'; (2) 'how does the interplay between coronal processes influence the end elemental abundances?'; and (3) 'what are the most probable release mechanisms'? We begin by analyzing the temporal and spatial variability of heavy ion dropouts and their correlation with heliospheric plasma and magnetic structures. Next we investigate the ordering of the elements inside dropouts with respect to mass, ionic charge state, and first ionization potential. Finally, we discuss these results in the context of the prevailing solar wind theories and the processes they posit that may be responsible for the release of coronal plasma into interplanetary space.

  15. CORONAL SOURCES, ELEMENTAL FRACTIONATION, AND RELEASE MECHANISMS OF HEAVY ION DROPOUTS IN THE SOLAR WIND

    International Nuclear Information System (INIS)

    Weberg, Micah J.; Lepri, Susan T.; Zurbuchen, Thomas H.

    2015-01-01

    The elemental abundances of heavy ions (masses larger than He) in the solar wind provide information about physical processes occurring in the corona. Additionally, the charge state distributions of these heavy ions are sensitive to the temperature profiles of their respective source regions in the corona. Heavy ion dropouts are a relatively new class of solar wind events identified by both elemental and ionic charge state distributions. We have shown that their origins lie in large, closed coronal loops where processes such as gravitational settling dominate and can cause a mass-dependent fractionation pattern. In this study we consider and attempt to answer three fundamental questions concerning heavy ion dropouts: (1) 'where are the source loops located in the large-scale corona?'; (2) 'how does the interplay between coronal processes influence the end elemental abundances?'; and (3) 'what are the most probable release mechanisms'? We begin by analyzing the temporal and spatial variability of heavy ion dropouts and their correlation with heliospheric plasma and magnetic structures. Next we investigate the ordering of the elements inside dropouts with respect to mass, ionic charge state, and first ionization potential. Finally, we discuss these results in the context of the prevailing solar wind theories and the processes they posit that may be responsible for the release of coronal plasma into interplanetary space

  16. Low frequency alternating current conduction and dielectric relaxation in polypyrrole irradiated with 100 MeV swift heavy ions of silver (Ag{sup 8+})

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Amarjeet, E-mail: amarkaur@physics.du.ac.in [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Dhillon, Anju [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Avasthi, D.K. [Inter University Accelerator Center (IUAC), Aruna Asaf Ali Road, New Delhi 110067 (India)

    2013-07-15

    Polypyrrole (PPY) films were prepared by electrochemical polymerization technique. The fully undoped samples were irradiated with different radiation fluences ranging from 10{sup 10} to 10{sup 12} ions cm{sup −2} of 100 MeV silver (Ag{sup 8+}) ions. The temperature dependence of ac conductivity [σ{sub m}(ω)], dielectric constant (ε′) and dielectric loss (ε′′) of both irradiated as well as unirradiated samples have been investigated in 77–300 K. There exists typical Debye type dispersion. Giant increase in dielectric constant has been observed for irradiated samples which is attributed to polaronic defects produced during irradiation. - Graphical abstract: Display Omitted - Highlights: • Polypyrrole samples were prepared by electrochemical technique. • The fully undoped samples were irradiated with 100 MeV silver (Ag{sup 8+}) ions. • Giant increase in dielectric constant in irradiated samples is observed. • Dielectric behaviour is attributed to polaronic defects produced during irradiation.

  17. Low frequency alternating current conduction and dielectric relaxation in polypyrrole irradiated with 100 MeV swift heavy ions of silver (Ag8+)

    International Nuclear Information System (INIS)

    Kaur, Amarjeet; Dhillon, Anju; Avasthi, D.K.

    2013-01-01

    Polypyrrole (PPY) films were prepared by electrochemical polymerization technique. The fully undoped samples were irradiated with different radiation fluences ranging from 10 10 to 10 12 ions cm −2 of 100 MeV silver (Ag 8+ ) ions. The temperature dependence of ac conductivity [σ m (ω)], dielectric constant (ε′) and dielectric loss (ε′′) of both irradiated as well as unirradiated samples have been investigated in 77–300 K. There exists typical Debye type dispersion. Giant increase in dielectric constant has been observed for irradiated samples which is attributed to polaronic defects produced during irradiation. - Graphical abstract: Display Omitted - Highlights: • Polypyrrole samples were prepared by electrochemical technique. • The fully undoped samples were irradiated with 100 MeV silver (Ag 8+ ) ions. • Giant increase in dielectric constant in irradiated samples is observed. • Dielectric behaviour is attributed to polaronic defects produced during irradiation

  18. Designing antimicrobial bioactive glass materials with embedded metal ions synthesized by the sol–gel method

    Energy Technology Data Exchange (ETDEWEB)

    Palza, Humberto, E-mail: hpalza@ing.uchile.cl [Departamento de Ingeniería Química y Biotecnología, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Santiago (Chile); Escobar, Blanca; Bejarano, Julian [Departamento de Ingeniería Química y Biotecnología, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Santiago (Chile); Bravo, Denisse [Departamento de Patología, Facultad de Odontología, Universidad de Chile, Santiago (Chile); Diaz-Dosque, Mario [Departamento de Ciencias Básicas y Comunitarias, Facultad de Odontología, Universidad de Chile, Santiago (Chile); Perez, Javier [Departamento de Ingeniería Química y Biotecnología, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Santiago (Chile)

    2013-10-15

    Bioactive glasses (SiO{sub 2}–P{sub 2}O{sub 5}–CaO) having tailored concentrations of different biocide metal ions (copper or silver) were produced by the sol–gel method. All the particles release phosphorous ions when immersed in water and simulated body fluid (SBF). Moreover, a surface layer of polycrystalline hydroxy-carbonate apatite was formed on the particle surfaces after 10 day immersion in SBF as confirmed by X-ray diffraction and scanning electron microscopy (SEM) showing the bioactive materials. Samples with embedded either copper or silver ions were able to further release the biocide ions with a release rate that depends on the metal embedded and the dissolution medium: water or SBF. This biocide ion release from the samples explains the antimicrobial effect of our active particles against Escherichia coli DH5α ampicillin-resistant (Gram-negative) and Streptococcus mutans (Gram-positive) as determined by the Minimum Bactericidal Concentration (MBC) method. The antimicrobial behavior of the particles depends on the bacteria and the biocide ion used. Noteworthy, although samples with copper are able to release more metal ion than samples with silver, they present higher MBC showing the high effect of silver against these bacteria. - Highlights: • Copper and silver act as antimicrobial additives in bioactive glass materials. • Silver is more toxic than copper ions in these bioactive materials. • Sol–gel method allows the synthesis of antimicrobial bioactive materials.

  19. Designing antimicrobial bioactive glass materials with embedded metal ions synthesized by the sol–gel method

    International Nuclear Information System (INIS)

    Palza, Humberto; Escobar, Blanca; Bejarano, Julian; Bravo, Denisse; Diaz-Dosque, Mario; Perez, Javier

    2013-01-01

    Bioactive glasses (SiO 2 –P 2 O 5 –CaO) having tailored concentrations of different biocide metal ions (copper or silver) were produced by the sol–gel method. All the particles release phosphorous ions when immersed in water and simulated body fluid (SBF). Moreover, a surface layer of polycrystalline hydroxy-carbonate apatite was formed on the particle surfaces after 10 day immersion in SBF as confirmed by X-ray diffraction and scanning electron microscopy (SEM) showing the bioactive materials. Samples with embedded either copper or silver ions were able to further release the biocide ions with a release rate that depends on the metal embedded and the dissolution medium: water or SBF. This biocide ion release from the samples explains the antimicrobial effect of our active particles against Escherichia coli DH5α ampicillin-resistant (Gram-negative) and Streptococcus mutans (Gram-positive) as determined by the Minimum Bactericidal Concentration (MBC) method. The antimicrobial behavior of the particles depends on the bacteria and the biocide ion used. Noteworthy, although samples with copper are able to release more metal ion than samples with silver, they present higher MBC showing the high effect of silver against these bacteria. - Highlights: • Copper and silver act as antimicrobial additives in bioactive glass materials. • Silver is more toxic than copper ions in these bioactive materials. • Sol–gel method allows the synthesis of antimicrobial bioactive materials

  20. A flow injection analysis system for monitoring silver (I) ion and iodine residuals in recycled water from recovery systems used for spaceflight

    International Nuclear Information System (INIS)

    Williamson, Jill P.; Emmert, Gary L.

    2013-01-01

    Graphical abstract: A device for on-line monitoring of the water disinfectants silver (I) ion or iodine in recycled water is presented. Simply change the reagents and the sample loop volume to switch between silver ion and iodine configurations. -- Highlights: •Automated FIA device for monitoring Ag + or I 2 residuals in recycled drinking water. •Method detection limits of Ag + of 52 μg L −1 and I 2 of 2 μg L −1 . •Mean % recoveries for Ag + of 104 ± 1% and for I 2 of 96.2 ± 0.1%. •% relative standard deviation estimates for Ag + of 1.4% and for I 2 of 5.7%. •Bias measurements agreed to 11.3 μg L −1 for Ag + and to 27.3 μg L −1 for I 2 . -- Abstract: A laboratory-built flow injection analyzer is reported for monitoring the drinking water disinfectants silver (I) ion and iodine in water produced from NASA's water recovery system. This analyzer uses spectrophotometric detection with a custom made 10 cm optical flow cell. Optimization and interference studies are discussed for the silver (I) ion configuration. Subsequent results using the silver (I) configuration with minor modifications and alternative reagents gave promising results for iodine determinations as well. The estimated MDL values for Ag + and I 2 are 52 μg L −1 Ag + and 2 μg L −1 I 2 ; the mean percent recoveries were 104% and 96.2% for Ag + and I 2 respectfully; and percent relative standard deviations were estimated at 1.4% for Ag + and 5.7% for I 2 . The agreement of this potentially multifunctional analyzer to reference methods for each respective water disinfectant is measured using Bland–Altman analysis as well as more traditional estimates

  1. Silver nanoparticle-enriched diamond-like carbon implant modification as a mammalian cell compatible surface with antimicrobial properties

    Science.gov (United States)

    Gorzelanny, Christian; Kmeth, Ralf; Obermeier, Andreas; Bauer, Alexander T.; Halter, Natalia; Kümpel, Katharina; Schneider, Matthias F.; Wixforth, Achim; Gollwitzer, Hans; Burgkart, Rainer; Stritzker, Bernd; Schneider, Stefan W.

    2016-01-01

    The implant-bone interface is the scene of competition between microorganisms and distinct types of tissue cells. In the past, various strategies have been followed to support bony integration and to prevent bacterial implant-associated infections. In the present study we investigated the biological properties of diamond-like carbon (DLC) surfaces containing silver nanoparticles. DLC is a promising material for the modification of medical implants providing high mechanical and chemical stability and a high degree of biocompatibility. DLC surface modifications with varying silver concentrations were generated on medical-grade titanium discs, using plasma immersion ion implantation-induced densification of silver nanoparticle-containing polyvinylpyrrolidone polymer solutions. Immersion of implants in aqueous liquids resulted in a rapid silver release reducing the growth of surface-bound and planktonic Staphylococcus aureus and Staphylococcus epidermidis. Due to the fast and transient release of silver ions from the modified implants, the surfaces became biocompatible, ensuring growth of mammalian cells. Human endothelial cells retained their cellular differentiation as indicated by the intracellular formation of Weibel-Palade bodies and a high responsiveness towards histamine. Our findings indicate that the integration of silver nanoparticles into DLC prevents bacterial colonization due to a fast initial release of silver ions, facilitating the growth of silver susceptible mammalian cells subsequently. PMID:26955791

  2. The physical properties and ion release of CPP-ACP-modified calcium silicate-based cements.

    Science.gov (United States)

    Dawood, A E; Manton, D J; Parashos, P; Wong, Rhk; Palamara, Jea; Stanton, D P; Reynolds, E C

    2015-12-01

    This study investigated the physical properties and ion release of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP)-modified calcium silicate-based cements (CSCs) and compared the properties of a trial mineral trioxide aggregate (MTA) with two commercially available CSCs, Biodentine(™) and Angelus(®) MTA. The setting time, solubility, compressive strength and Vickers surface microhardness of the three CSCs incorporated with 0%, 0.5%, 1.0%, 2.0% and 3.0% (w/w) CPP-ACP were investigated. Release of calcium (Ca(2+) ), phosphate ions (Pi ) and pH of the test cements were measured after 24, 72, 168 and 336 h of storage. The addition of up to 1.0% CPP-ACP into Biodentine(™) and 0.5% into the other cements did not adversely affect their physical properties except for the setting time. The addition of 0.5% CPP-ACP increased Ca(2+) released from Biodentine(™) (after 168 and 336 h), Angelus(®) MTA (after 168 h) and the trial MTA (after 72 h). The addition of 1.0-3.0% CPP-ACP increased Ca(2+) and Pi released from all the cements. Biodentine(™) released more Ca(2+) particularly in the early stages and showed shorter setting time and higher mechanical properties than the other cements. The mechanical properties of Angelus(®) MTA and the trial MTA were similar. All the cements produced highly alkaline storage solutions. Up to 1.0% CPP-ACP in Biodentine(™) improves Ca(2+) and Pi release and 0.5% CPP-ACP in Angelus(®) MTA and the trial MTA improves Ca(2+) release without altering the mechanical properties and solubility. The addition of CPP-ACP into CSCs prolonged the setting time. © 2015 Australian Dental Association.

  3. Effect of silver ions on the energy transfer from host defects to Tb ions in sol–gel silica glass

    Energy Technology Data Exchange (ETDEWEB)

    Abbass, Abd Ellateef [Department of Physics, University of the Free State, Bloemfontein (South Africa); Department of Physics, Sudan University of Science and Technology (Sudan); Swart, H.C. [Department of Physics, University of the Free State, Bloemfontein (South Africa); Kroon, R.E., E-mail: KroonRE@ufs.ac.za [Department of Physics, University of the Free State, Bloemfontein (South Africa)

    2015-04-15

    Plasmonic metal structures have been suggested to enhance the luminescence from rare-earth (RE) ions, but this enhancement is not yet well understood or applied to phosphor materials. Although some reports using Ag nanoparticles (NPs) in glass have attributed enhancement of RE emission to the strong electric fields associated with Ag NPs, it has also been proposed that the enhancement is instead due to energy transfer from Ag ions to RE ions. Our work using sol–gel silica shows a third possibility, namely that enhancement of the RE (e.g. Tb) emission is due to energy transfer from defects of the host material to the Tb ions, where the addition of Ag influences the silica host defects. The oxidation state of Ag as a function of annealing temperature was investigated by x-ray diffraction, transmission electron microscopy, UV–vis measurements and x-ray photoelectron spectroscopy, while optical properties were investigated using a Cary Eclipse fluorescence spectrophotometer or by exciting samples with a 325 nm He–Cd laser. The results showed that Ag ions have a significant effect on the silica host defects, which resulted in enhancement of the green Tb emission at 544 nm for non-resonant excitation using a wavelength of 325 nm. - Highlights: • Conversion of Ag ions to metallic nanoparticles after annealing of sol–gel silica. • Addition of Ag resulted in enhanced green luminescence from Tb ions in silica. • Enhancement is attributed to the effect of added Ag on the host defects of silica.

  4. Mechanisms of Silver Nanoparticle Release, Transformation and Toxicity: A Critical Review of Current Knowledge and Recommendations for Future Studies and Applications

    Directory of Open Access Journals (Sweden)

    Iseult Lynch

    2013-06-01

    Full Text Available Nanosilver, due to its small particle size and enormous specific surface area, facilitates more rapid dissolution of ions than the equivalent bulk material; potentially leading to increased toxicity of nanosilver. This, coupled with their capacity to adsorb biomolecules and interact with biological receptors can mean that nanoparticles can reach sub-cellular locations leading to potentially higher localized concentrations of ions once those particles start to dissolve or degrade in situ. Further complicating the story is the capacity for nanoparticles to generate reactive oxygen species, and to interact with, and potentially disturb the functioning of biomolecules such as proteins, enzymes and DNA. The fact that the nanoparticle size, shape, surface coating and a host of other factors contribute to these interactions, and that the particles themselves are evolving or ageing leads to further complications in terms of elucidating mechanisms of interaction and modes of action for silver nanoparticles, in contrast to dissolved silver species. This review aims to provide a critical assessment of the current understanding of silver nanoparticle toxicity, as well as to provide a set of pointers and guidelines for experimental design of future studies to assess the environmental and biological impacts of silver nanoparticles. In particular; in future we require a detailed description of the nanoparticles; their synthesis route and stabilisation mechanisms; their coating; and evolution and ageing under the exposure conditions of the assay. This would allow for comparison of data from different particles; different environmental or biological systems; and structure-activity or structure-property relationships to emerge as the basis for predictive toxicology. On the basis of currently available data; such comparisons or predictions are difficult; as the characterisation and time-resolved data is not available; and a full understanding of silver

  5. Mega-electron-volt ion beam induced anisotropic plasmon resonance of silver nanocrystals in glass

    NARCIS (Netherlands)

    Penninkhof, JJ; Polman, A; Sweatlock, LA; Maier, SA; Atwater, HA; Vredenberg, AM; Kooi, BJ; Sweatlock, Luke A.; Maier, Stefan A.

    2003-01-01

    30 MeV Si ion beam irradiation of silica glass containing Ag nanocrystals causes alignment of Ag nanocrystals in arrays along the ion tracks. Optical transmission measurements show a large splitting of the surface plasmon resonance bands for polarizations longitudinal and transversal to the arrays.

  6. Improvement of date palm plant lets during rooting stage by silver ion

    International Nuclear Information System (INIS)

    Sharaf, M.M.; Khamis, M.A.; El Bana, A.; Abd El Galeil, L.M.; Zaid, Z.E.

    2012-01-01

    This study aim to promote growth plant lets of date palm cv. Zaghlool by decreasing ethylene production inside the containers during rooting stage. Data obtained declared that three silver thiosulphate (STS) levels added to one half strength MS rooting medium improved significantly three rooting measurements (rooting percentage; number and length of developed root lets). However, the lightest STS level (0.25 ml/L of 4 mM STS solution) was the superior, while highest one (1.0 ml/L) was the inferior from statistical point of view. Data obtained displayed that providing MS rooting medium with silver nitrate improved 3 rooting measurements (rooting %; number of root lets and their length) for Zaghloul date palm shoot lets proliferated from somatic embryos. However, the 0.50 mg/L AgNO 3 provided MS medium was the most preferable in this concern. Plant lets were transferred to capped tubes contained 1/4 liquid MS medium through 3 weeks in the growth chamber (under aseptic condition). Ventilation was allowed gradually by punching holes in aluminum foil caps during first five days of 2 nd week. After then, the plant lets were transplanted in acclimatization green house on mixture from (peat moss + perlite + vermiculite at 1:1:1) and survival percentage was 75% after three months.

  7. Experimental composite guidance conduits for peripheral nerve repair: An evaluation of ion release

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, X.F. [Department of Biological Sciences and Medical Engineering Design and Innovation Centre, Cork Institute of Technology, Cork (Ireland); Coughlan, A. [Inamori School of Engineering, Alfred University, Alfred, NY. 14802 (United States); O' Shea, H. [Department of Biological Sciences and Medical Engineering Design and Innovation Centre, Cork Institute of Technology, Cork (Ireland); Towler, M.R. [Inamori School of Engineering, Alfred University, Alfred, NY. 14802 (United States); Kehoe, S., E-mail: sharonkehoe@dal.ca [Department of Applied Oral Sciences, Dalhousie University, Halifax, NS, B3H 4R2 (Canada); School of Biomedical Engineering, Dalhousie University, Halifax, NS, B3H 4R2 (Canada); Boyd, D., E-mail: d.boyd@dal.ca [Department of Applied Oral Sciences, Dalhousie University, Halifax, NS, B3H 4R2 (Canada); School of Biomedical Engineering, Dalhousie University, Halifax, NS, B3H 4R2 (Canada)

    2012-08-01

    Poly (lactide-co-glycolide) (PLGA) - Pluronic F127 - glass composites have demonstrated excellent potential, from the perspective of controlled mechanical properties and cytocompatibility, for peripheral nerve regeneration. In addition to controlling the mechanical properties and cytotoxicity for such composite devices, the glass component may mediate specific responses upon implantation via degradation in the physiological environment and release of constituent elements. However, research focused on quantifying the release levels of such therapeutic ions from these experimental medical devices has been limited. To redress the balance, this paper explores the ion release profiles for Si{sup 4+}, Ca{sup 2+}, Na{sup +}, Zn{sup 2+}, and Ce{sup 4+} from experimental composite nerve guidance conduits (CNGC) comprising PLGA (at 12.5, and 20 wt.%), F127 (at 0, 2.5 and 5 wt.%) and various loadings of Si-Ca-Na-Zn-Ce glass (at 20 and 40 wt.%) for incubation periods of up to 28 days. The concentration of each ion, at various time points, was determined using Inductively Coupled Plasma-Atomic Emission Spectrometry (Perkin Elmer Optima 3000). It was observed that the Si{sup 4+}, Na{sup +}, Ca{sup 2+}, Zn{sup 2+} release from CNGCs in this study ranged from 0.22 to 6.477 ppm, 2.307 to 3.277 ppm, 40 to 119 ppm, and 45 to 51 ppm, respectively. The Ce{sup 4+} concentrations were under the minimum detection limits for the ICP instrument utilized. The results indicate that the ion release levels may be appropriate to mediate therapeutic effects with respect to peripheral nerve regeneration. The data generated in this paper provides requisite evidence to optimize composition for pre-clinical evaluation of the experimental composite. - Graphical abstract: Highlights: Black-Right-Pointing-Pointer Time-dependent degradation studies of PLGA/glass composite nerve guidance conduits (NGCs). Black-Right-Pointing-Pointer Si{sup 4+}, Na{sup +}, Ca{sup 2+} and Zn{sup 2+} release levels for the

  8. Ion release from a composite resin after exposure to different 10% carbamide peroxide bleaching agents

    Directory of Open Access Journals (Sweden)

    Renata Plá Rizzolo Bueno

    2012-06-01

    Full Text Available OBJECTIVE: This in vitro study evaluated the influence of two 10% carbamide peroxide bleaching agents - a commercial product (Opalescence PF; Ultradent Products, Inc. and a bleaching agent prepared in a compounding pharmacy - on the chemical degradation of a light-activated composite resin by determining its release of ions before and after exposure to the agents. MATERIAL AND METHODS: Thirty composite resin (Filtek Z250; 3M/ESPE samples were divided into three groups: group I (exposed to Opalescence PF commercial bleaching agent, group II (exposed to a compounded bleaching agent and group III (control - Milli-Q water. After 14 days of exposure, with a protocol of 8 h of daily exposure to the bleaching agents and 16 h of immersion in Milli-Q water, the analysis of ion release was carried out using a HP 8453 spectrophotometer. The values were analyzed statistically by ANOVA, Tukey's test and the paired t-tests. The significance level was set at 5%. RESULTS: After 14 days of the experiment, statistically significant difference was found between group II and groups I and III, with greater ion release from the composite resin in group II. CONCLUSIONS: The compounded bleaching agent had a more aggressive effect on the composite resin after 14 days of exposure than the commercial product and the control (no bleaching.

  9. The effect of platform switching on the levels of metal ion release from different implant–abutment couples

    Science.gov (United States)

    Alrabeah, Ghada O; Knowles, Jonathan C; Petridis, Haralampos

    2016-01-01

    The improved peri-implant bone response demonstrated by platform switching may be the result of reduced amounts of metal ions released to the surrounding tissues. The aim of this study was to compare the levels of metal ions released from platform-matched and platform-switched implant–abutment couples as a result of accelerated corrosion. Thirty-six titanium alloy (Ti-6Al-4V) and cobalt–chrome alloy abutments were coupled with titanium cylinders forming either platform-switched or platform-matched groups (n=6). In addition, 18 unconnected samples served as controls. The specimens were subjected to accelerated corrosion by static immersion in 1% lactic acid for 1 week. The amount of metal ions ion of each test tube was measured using inductively coupled plasma mass spectrometry. Scanning electron microscope (SEM) images and energy dispersive spectroscopy X-ray analyses were performed pre- and post-immersion to assess corrosion at the interface. The platform-matched groups demonstrated higher ion release for vanadium, aluminium, cobalt, chrome, and molybdenum compared with the platform-switched groups (Pabutment size or connection (Pabutment platform surfaces. In conclusion, implant–abutment couples underwent an active corrosion process resulting in metal ions release into the surrounding environment. The highest amount of metal ions released was recorded for the platform-matched groups, suggesting that platform-switching concept has a positive effect in reducing the levels of metal ion release from the implant–abutment couples. PMID:27357323

  10. Antibacterial potency of V.A.C. GranuFoam Silver(®) Dressing.

    Science.gov (United States)

    Sachsenmaier, Saskia; Peschel, Andreas; Ipach, Ingmar; Kluba, Torsten

    2013-10-01

    V.A.C.(®) GranuFoam™ therapy is regularly used in the surgical therapy of infected wounds and soft tissue injuries. Silver nanoparticles can destroy bacterial cell walls and inhibit enzymes for cell replication. Silver dressings are therefore successfully used for many indications in wound therapy. In this study, we investigated the antimicrobial potency of ionic silver released from the silver-coated V.A.C.(®) GranuFoam™ during vacuum therapy. Silver dressing was exposed to agar plates populated with bacteria to measure silver release. A total of 15 agar plates colonised with either Staphylococcus aureus populations or with Staphylococcus epidermidis, were loaded with V.A.C. GranuFoam Silver(®) Dressing polyurethane foam (KCI, San Antonio, Texas). Each of 13 pieces of silver-coated foam was applied to an agar plate. Two plates were loaded with conventional black foam without any coating. After connecting to a vacuum pump, the vacuum therapy of the 15 plates lasted 5 days. The zone of inhibition of bacterial growth around the foam was measured daily. Silver release was also determined as a function of time. At each time point, there was evidence of silver in the agar independent of bacterial colonisation. The S. aureus agar showed a consecutive increase in silver concentration from baseline upon 48 h after exposure to the negative pressure of V.A.C. therapy. An increasing mean silver level after 48, 72 and 96 h was measured under V.A.C. therapy with a peak value after 120 h. In contrast, the results from the S. epidermidis plates did not follow a linear pattern. At the beginning of vacuum therapy, we documented a rise in silver concentration. After 48-96h, the silver levels fluctuated. A maximum zone of inhibition in both bacterial colonised plates (S. aureus and S. epidermidis) was found 39 h after the start of the V.A.C. GranuFoam Silver(®) therapy. From our results, we confirmed the antimicrobial effect of the silver ions against S. aureus and S

  11. An Investigation on Metallic Ion Release from Four Dental Casting Alloys

    Directory of Open Access Journals (Sweden)

    F. Nejatidanesh

    2005-12-01

    Full Text Available Statement of Problem: Element release from dental casting alloys into the oral environment is of clinical concern and is considered to be a potential health problem to all patients.Purpose: The aim of this study was to investigate the metallic ion release of four base metal alloys.Materials and Methods: Two Ni-Cr (Minalux and Supercast and two Co-Cr alloys (Minalia and Wironit were examined. Nine specimens of each type were prepared in 13×11×1.4 mm dimensions and each of the four alloys (3 specimens per group were conditioned in artificial saliva at 37 c for one, three and seven days.The conditioning media were analyzed for element-release using Inductive CoupledPlasma Atomic Emission Spectrophotometer (ICPAES. Collected data were statistically analyzed using ANOVA and Duncan multiple range test (P< 0.05.Results: The greatest amount of element release was seen after seven days (134.9 ppb Supercast, 159.2 ppb Minalux, 197.2 ppb Minalia, and 230.2 ppb Wironit. There was a significant difference between the released elements from the alloys after the three conditioning times (p<0.001.Conclusion: Element release from the studied alloys is proportional to the conditioning time. The Ni-Cr alloys tested in this investigation were more resistant to corrosion as compared to the Co-Cr alloys in artificial saliva. Supercast had the highest corrosion resistance.

  12. Literature study of volatile radioiodine release from ion-exchange resins during transportation

    International Nuclear Information System (INIS)

    Wren, J.C.

    1991-02-01

    A transport package is currently being developed by Ontario Hydro to carry used filters and ion-exchange columns from the Pickering and Darlington Nuclear Generating Stations to the Bruce Nuclear Generating Station for disposal. The main reason that the transport package must be licensed is the possibility that volatile radionuclides being transported in the package might be released during transport accidents. Of particular concern is the iodine that might become volatile due to the degradation of the ion exchange resin. This report reviews the literature on the thermal and radiolytic degradation of ion exchange resins and provides calculations to estimate the fraction of volatile iodine as a function of time under postulated accident conditions

  13. Therapeutic ion-releasing bioactive glass ionomer cements with improved mechanical strength and radiopacity

    Directory of Open Access Journals (Sweden)

    Maximilian eFuchs

    2015-10-01

    Full Text Available Bioactive glasses (BG are used to regenerate bone, as they degrade and release therapeutic ions. Glass ionomer cements (GIC are used in dentistry, can be delivered by injection and set in situ by a reaction between an acid-degradable glass and a polymeric acid. Our aim was to combine the advantages of BG and GIC, and we investigated the use of alkali-free BG (SiO2-CaO-CaF2-MgO with 0 to 50% of calcium replaced by strontium, as the beneficial effects of strontium on bone formation are well documented. When mixing BG and poly(vinyl phosphonic-co-acrylic acid, ions were released fast (up to 90% within 15 minutes at pH 1, which resulted in GIC setting, as followed by infrared spectroscopy. GIC mixed well and set to hard cements (compressive strength up to 35 MPa, staying hard when in contact with aqueous solution. This is in contrast to GIC prepared with poly(acrylic acid, which were shown previously to become soft in contact with water. Strontium release from GIC increased linearly with strontium for calcium substitution, allowing for tailoring of strontium release depending on clinical requirements. Furthermore, strontium substitution increased GIC radiopacity. GIC passed ISO10993 cytotoxicity test, making them promising candidates for use as injectable bone cements.

  14. Radar observations of ion cyclotron waves associated with two barium shaped-charge releases

    International Nuclear Information System (INIS)

    Providakes, J.; Swartz, W.E.; Kelley, M.C.; Djuth, F.T.; Noble, S.; Jost, R.J.

    1990-01-01

    A 50-MHz Doppler radar interferometer and a 138-MHz Doppler radar were operated from Kennedy Space Center to study 3-m and 1-m plasma waves associated with two shaped-charged barium releases from Wallops Island, Virginia, on May 13, 1986. During the first release, interferometer and Doppler power spectral studies showed the existence of short-lived ( + EIC waves were unstable for field-aligned electron drifts greater than 0.7υ the at the altitude of 510 km in a multispecies (O + , NO + , or similarly O 2 + ) ionospheric plasma. The authors interpret the 30-Hz waves seen by the two radars far above the release as strong electrostatic ion cyclotron waves generated by intense field-aligned currents associated with the barium stream acting like an MHD generator coupled to the ionospheres

  15. Ion induced transformation of polymer films into diamond-like carbon incorporating silver nano particles; Ioneninduzierte Umwandlung von Polymerschichten zu diamantaehnlichem Kohlenstoff mit darin enthaltenen Silber-Nanopartikeln

    Energy Technology Data Exchange (ETDEWEB)

    Schwarz, Florian P.

    2010-03-26

    Silver containing diamond-like carbon (DLC) is an interesting material for medical engineering from several points of view. On the one hand DLC provides high mechanical robustness. It can be used as biocompatible and wear resistant coating for joint replacing implants. On the other hand silver has antimicrobial properties, which could reduce post-operative inflammations. However conventional production of Ag-DLC by co-deposition of silver and carbon in a plasma process is problematic since it does not allow for a separate control of nano particle morphology and matrix properties. In this work an alternative production method has been developed to circumvent this problem. In metall-DLC-production by ion implantation into a nano composite, silver nano particles are initially formed in solution and then incorporated within a polymer matrix. Finally the polymer is transformed into DLC by ion implantation. The aspects and single steps of this method were investigated with regard to the resulting material's properties. The goal was to design an economically relevant deposition method. Based on experimental results a model of the transformation process has been established, which has also been implemented in a computer simulation. Finally the antibacterial properties of the material have been checked in a biomedical test. Here a bacterial killing rate of 90% could be achieved. (orig.)

  16. Silver ion imprinted polymer nanobeads based on a aza-thioether crown containing a 1,10-phenanthroline subunit for solid phase extraction and for voltammetric and potentiometric silver sensors

    Energy Technology Data Exchange (ETDEWEB)

    Shamsipur, Mojtaba, E-mail: mshamsipur@yahoo.com [Department of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Hashemi, Beshare; Dehdashtian, Sara; Mohammadi, Moslem; Gholivand, Mohammad Bagher [Department of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Garau, Alessandra; Lippolis, Vito [Dipartimento di Scienze Chimiche e Geologiche, Universita' degli Studi di Cagliari, S.S. 554 Bivio per Sestu, 09042 Monserrato, CA (Italy)

    2014-12-10

    Highlights: • Preparation of Ag{sup +} imprinted polymeric nanobeads via precipitation polymerization. • Use of a mixed aza-thioether crown containing a 1,10-phenanthroline subunit a selective host for Ag{sup +} ion. • Highly selective, sensitive and fast recognition of traces of Ag{sup +} ions. • Use of the prepared Ag{sup +}-IIP for preparation of an Ag{sup +}-voltammetric sensor with LOD of 9.0 × 10{sup −10} M. • Use of the prepared Ag{sup +}-IIP for preparation of Ag{sup +}-ISEs with LOD of 1.2 × 10{sup −9} M 9.0 × 10{sup −10} M. - Abstract: A new nano-sized silver(I) ion-imprinted polymer (IIP) was prepared via precipitation copolymerization using ethyleneglycol dimethacrylate, as a cross-linking agent in the presence of Ag{sup +} and an aza-thioether crown containing a 1,10-phenanthroline subunit as a highly selective complexing agent. The imprint silver(I) ion was removed from the polymeric matrix using a 1.0 M HNO{sub 3} solution. The resulting powder material was characterized using IR spectroscopy and scanning electron microscopy. The SEM micrographs showed colloidal nanoparticles of about 52 nm and 75 nm in diameter and slightly irregular in shape for leached and unleached IIPs, respectively. The optimal pH for quantitative enrichment was 6.0 and maximum sorbent capacity of the prepared IIP for Ag{sup +} was 18.08 μmol g{sup −1}. The relative standard deviation and limit of detection (LOD = 3S{sub b}/m) for flame atomic absorption spectrometric determination of silver(I) ion, after its selective extraction by the prepared IIP nanobeads, were evaluated as 2.42% and 2.2 × 10{sup −8} M, respectively. The new Ag{sup +}-IIP was also applied as a suitable sensing element to the preparation of highly selective and sensitive voltammetric and potentiometric sensors for ultra trace detection of silver(I) ion in water samples, with limits of detection of 9.0 × 10{sup −10} and 1.2 × 10{sup −9} M, respectively.

  17. Three-dimensional endothelial cell morphogenesis under controlled ion release from copper-doped phosphate glass.

    Science.gov (United States)

    Stähli, Christoph; James-Bhasin, Mark; Nazhat, Showan N

    2015-02-28

    Copper ions represent a promising angiogenic agent but are associated with cytotoxicity at elevated concentrations. Phosphate-based glasses (PGs) exhibit adjustable dissolution properties and allow for controlled ion release. This study examined the formation of capillary-like networks by SVEC4-10 endothelial cells (ECs) seeded in a three-dimensional (3D) type I collagen hydrogel matrix mixed with PG particles of the formulation 50P2O5-30CaO-(20-x)Na2O-xCuO (x=0 and 10 mol%). Copper and total phosphorus release decreased over time and was more sustained in the case of 10% CuO PG. Moreover, increasing the concentration of 10% CuO PG in collagen substantially delayed dissolution along with preferential release of copper. A 3D morphometric characterization method based on confocal laser scanning microscopy image stacks was developed in order to quantify EC network length, connectivity and branching. Network length was initially reduced in a concentration-dependent fashion by 10% CuO PG and, to a lesser extent, by 0% CuO PG, but reached values identical to the non-PG control by day 5 in culture. This reduction was attributed to a PG-mediated decrease in cell metabolic activity while cell proliferation as well as network connectivity and branching were independent of PG content. Gene expression of matrix metalloproteinases (MMP)-1 and -2 was up-regulated by PGs, indicating that MMPs did not play a critical role in network growth. The relationship between ion release and EC morphogenesis in 3D provided in this study is expected to contribute to an ultimately successful pro-angiogenic application of CuO-doped PGs. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. DNA-functionalized gold nanoparticle-based fluorescence polarization for the sensitive detection of silver ions.

    Science.gov (United States)

    Wang, Gongke; Wang, Shuangli; Yan, Changling; Bai, Guangyue; Liu, Yufang

    2018-04-05

    Despite their practical applications, Ag + ions are environmental pollutants and affect human health. So the effective detection methods of Ag + ions are imperative. Herein, we developed a simple, sensitive, selective, and cost-effective fluorescence polarization sensor for Ag + detection in aqueous solution using thiol-DNA-functionalized gold nanoparticles (AuNPs). In this sensing strategy, Ag + ions can specifically interact with a cytosine-cytosine (CC) mismatch in DNA duplexes and form stable metal-mediated cytosine-Ag + -cytosine (C-Ag + -C) base pairs. The formation of the C-Ag + -C complex results in evident changes in the molecular volume and fluorescence polarization signal. To achieve our aims, we prepared two complementary DNA strands containing C-base mismatches (probe A: 5'-SH-A 10 -TACCACTCCTCAC-3' and probe B: 5'-TCCTCACCAGTCCTA-FAM-3'). The stable hybridization between probe A and probe B occurs with the formation of the C-Ag + -C complex in the presence of Ag + ions, leading to obvious fluorescence quenching in comparison to the system without AuNP enhancement. The assay can be used to identify nanomolar levels of Ag + within 6 min at room temperature, and has extremely high specificity for Ag + , even in the presence of higher concentrations of interfering metal ions. Furthermore, the sensor was successfully applied to the detection of Ag + ions in environmental water samples and showed excellent selectivity and high sensitivity, implying its promising application in the future. Copyright © 2018 Elsevier B.V. All rights reserved.

  19. Silver ion beam irradiation effects on poly(lactide-co-glycolide) (PLGA)/clay nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Manpreet; Singh, Surinder [Guru Nanak Dev University, Department of Physics, Amritsar (India); Mehta, Rajeev [Thapar University, Department of Chemical Engineering, Patiala (India)

    2014-12-15

    Swift heavy ions induced modification of thin films of blends of poly(lactide-co-glycolide) (PLGA) (50:50) with organically modified nanoclay (Cloisite {sup registered} 30B) has been studied, using optical, structural and surface morphological analysis. Presence of nanoclay is found to enhance the properties of this degradable copolymer by reducing the rate of degradation even at high irradiation fluence. Optical and structural analysis of the polymer nanocomposites suggests that both the cross-linking and chain scission phenomenon are caused by swift heavy ion irradiation. XRD measurements show intercalation of PLGA in the clay galleries. Surface morphology of a nanocomposite indicates significant changes after irradiation at various fluences. (orig.)

  20. Metal ions released from fixed orthodontic appliance affect hair mineral content.

    Science.gov (United States)

    Mikulewicz, Marcin; Wołowiec, Paulina; Loster, Bartłomiej; Chojnacka, Katarzyna

    2015-02-01

    The objective was to evaluate metal ion accumulation in hair of patients undergoing orthodontic treatment with fixed appliances in time. The patients (N = 47) participated in a questionnaire survey. Hair sampling was performed at the beginning and in the 4th, 8th, and 12th month of the treatment. The content of metals (Cr, Ni, Fe) in hair was analyzed by ICP-OES equipped with USN nebulizer. The peak release of Cr and Fe occurred after 4 months of the treatment, and the peak release of Ni gradually increased throughout the whole year of the therapy. During 1 year treatment, an average accumulation of metals in hair tissue was 7.42 ± 14.19 μg of Ni, 8.94 ± 13.1 μg of Cr, and 131 ± 279 μg of Fe. The mean content of Cr was higher than the 90th percentile value for this element. The upper limit of literature reference ranges for Cr, Ni, and Fe in hair was not exceeded. The value of exposure (kinetics and dose) of orthodontic patients to metal ions released from orthodontic appliances can be assessed by hair mineral analysis. The content of Cr was statistically significantly higher during the treatment than before the beginning of therapy.

  1. Pilot study on the identification of silver in skin layers and urine after dermal exposure to a functionalized textile

    NARCIS (Netherlands)

    Bianco, Carlotta; Kezic, Sanja; Visser, Maaike J.; Pluut, Olivier A.; Adami, Gianpiero; Krystek, Petra

    2015-01-01

    Silver (Ag) is increasingly used in consumer products like functionalized textiles and medical devices owing to its strong antimicrobial activity which is largely assigned to Ag ions released after oxidation of metallic Ag. To increase generation of Ag ions, in various products Ag is often present

  2. Diffusion of Ag ions under random potential barriers in silver-containing chalcogenide glasses

    Czech Academy of Sciences Publication Activity Database

    Stehlík, Štěpán; Shimakawa, K.; Wágner, T.; Frumar, M.

    2012-01-01

    Roč. 45, č. 20 (2012), s. 1-5 ISSN 0022-3727 Institutional research plan: CEZ:AV0Z10100521 Keywords : Ag ion diffusion * chalcogenide glass * Nyquist plots Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.528, year: 2012 http://iopscience.iop.org/0022-3727/45/20/205304/

  3. Optical properties of ion beam modified waveguide materials doped with erbium and silver

    NARCIS (Netherlands)

    Strohhöfer, C. (Christof)

    2001-01-01

    In the first part of this thesis we investigate codoping of erbium-doped waveguide materials with different ions in order to increase the efficiency of erbium-doped optical amplifiers. Codoping with ytterbium can overcome the limitations due to the small absorption cross section of Er3+ in Al2O3 at

  4. Assessment of Ions released from Three Types of Orthodontic Brackets immersed in Different Mouthwashes: An in vitro Study.

    Science.gov (United States)

    Nahidh, Mohammed; Garma, Noor Mh; Jasim, Esraa S

    2018-01-01

    Herbs are used widely in medicine. The purpose of the present study was to assess the ion release from gold-plated orthodontic bracket compared with other stainless steel brackets, and based on the findings of the study, the orthodontists can choose the most biocompatible brackets and mouthwashes useful in the clinical practice. A total of 150 orthodontic brackets from Orthotechnology™ Company, USA (50 stainless steel one-piece brackets, 50 stainless steel two-piece brackets, and 50 gold brackets) were immersed in four mouthwashes in addition to distilled water. Ten of each type of brackets in every media were immersed under 37°C for 45 days. Ions released in these mouthwashes were measured, and comparisons among different bracket types and among various mouthwashes were done by one-way analysis of variance (ANOVA) and then with Games-Howell tests. Increased amounts of ions released in herbal mouth-washes were recorded in gold and two-piece brackets in comparison with one-piece stainless steel brackets. Herbal mouthwashes must be used with caution as they showed an increased amount of ions released in comparison with chlorhexidine. One-piece stainless steel bracket system is the most compatible bracket type, as they released the least amount of ions. One-piece stainless steel brackets are better than two-piece brackets in terms of ions released.

  5. Mass spectrometric characterizations of ions generated in RF magnetron discharges during sputtering of silver in Ne, Ar, Kr and Xe gases

    Czech Academy of Sciences Publication Activity Database

    Pokorný, D.; Novotný, Michal; Musil, Jindřich; Fitl, Přemysl; Bulíř, Jiří; Lančok, Ján

    2013-01-01

    Roč. 10, č. 7 (2013), s. 593-602 ISSN 1612-8850 R&D Projects: GA ČR(CZ) GAP108/11/1298; GA ČR(CZ) GAP108/11/1312; GA ČR(CZ) GAP108/11/0958 Grant - others:AVČR(CZ) M100101271 Institutional support: RVO:68378271 Keywords : double charge ions * mass spectrometry * noble gas * RF magnetron discharges * silver * single charge ions Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.964, year: 2013

  6. Short-term soil bioassays may not reveal the full toxicity potential for nanomaterials; bioavailability and toxicity of silver ions (AgNO₃) and silver nanoparticles to earthworm Eisenia fetida in long-term aged soils.

    Science.gov (United States)

    Diez-Ortiz, Maria; Lahive, Elma; George, Suzanne; Ter Schure, Anneke; Van Gestel, Cornelis A M; Jurkschat, Kerstin; Svendsen, Claus; Spurgeon, David J

    2015-08-01

    This study investigated if standard risk assessment hazard tests are long enough to adequately provide the worst case exposure for nanomaterials. This study therefore determined the comparative effects of the aging on the bioavailability and toxicity to earthworms of soils dosed with silver ions and silver nanoparticles (Ag NP) for 1, 9, 30 & 52 weeks, and related this to the total Ag in the soil, Ag in soil pore water and earthworm tissue Ag concentrations. For ionic Ag, a classical pattern of reduced bioavailability and toxicity with time aged in the soil was observed. For the Ag NP, toxicity increased with time apparently driven by Ag ion dissolution from the added Ag NPs. Internal Ag in the earthworms did not always explain toxicity and suggested the presence of an internalised, low-toxicity Ag fraction (as intact or transformed NPs) after shorter aging times. Our results indicate that short-term exposures, without long-term soil aging, are not able to properly assess the environmental risk of Ag NPs and that ultimately, with aging time, Ag ion and Ag NP effect will merge to a common value. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Complexes of silver(I) ions and silver phosphate nanoparticles with hyaluronic acid and/or chitosan as promising antimicrobial agents for vascular grafts.

    Science.gov (United States)

    Chudobova, Dagmar; Nejdl, Lukas; Gumulec, Jaromir; Krystofova, Olga; Rodrigo, Miguel Angel Merlos; Kynicky, Jindrich; Ruttkay-Nedecky, Branislav; Kopel, Pavel; Babula, Petr; Adam, Vojtech; Kizek, Rene

    2013-06-28

    Polymers are currently widely used to replace a variety of natural materials with respect to their favourable physical and chemical properties, and due to their economic advantage. One of the most important branches of application of polymers is the production of different products for medical use. In this case, it is necessary to face a significant disadvantage of polymer products due to possible and very common colonization of the surface by various microorganisms that can pose a potential danger to the patient. One of the possible solutions is to prepare polymer with antibacterial/antimicrobial properties that is resistant to bacterial colonization. The aim of this study was to contribute to the development of antimicrobial polymeric material ideal for covering vascular implants with subsequent use in transplant surgery. Therefore, the complexes of polymeric substances (hyaluronic acid and chitosan) with silver nitrate or silver phosphate nanoparticles were created, and their effects on gram-positive bacterial culture of Staphylococcus aureus were monitored. Stages of formation of complexes of silver nitrate and silver phosphate nanoparticles with polymeric compounds were characterized using electrochemical and spectrophotometric methods. Furthermore, the antimicrobial activity of complexes was determined using the methods of determination of growth curves and zones of inhibition. The results of this study revealed that the complex of chitosan, with silver phosphate nanoparticles, was the most suitable in order to have an antibacterial effect on bacterial culture of Staphylococcus aureus. Formation of this complex was under way at low concentrations of chitosan. The results of electrochemical determination corresponded with the results of spectrophotometric methods and verified good interaction and formation of the complex. The complex has an outstanding antibacterial effect and this effect was of several orders higher compared to other investigated complexes.

  8. Copper-transporting P-type ATPases use a unique ion-release pathway

    DEFF Research Database (Denmark)

    Andersson, Magnus; Mattle, Daniel; Sitsel, Oleg

    2014-01-01

    Heavy metals in cells are typically regulated by PIB-type ATPases. The first structure of the class, a Cu(+)-ATPase from Legionella pneumophila (LpCopA), outlined a copper transport pathway across the membrane, which was inferred to be occluded. Here we show by molecular dynamics simulations...... that extracellular water solvated the transmembrane (TM) domain, results indicative of a Cu(+)-release pathway. Furthermore, a new LpCopA crystal structure determined at 2.8-Å resolution, trapped in the preceding E2P state, delineated the same passage, and site-directed-mutagenesis activity assays support...... a functional role for the conduit. The structural similarities between the TM domains of the two conformations suggest that Cu(+)-ATPases couple dephosphorylation and ion extrusion differently than do the well-characterized PII-type ATPases. The ion pathway explains why certain Menkes' and Wilson's disease...

  9. Hepatitis E virus ORF3 is a functional ion channel required for release of infectious particles.

    Science.gov (United States)

    Ding, Qiang; Heller, Brigitte; Capuccino, Juan M V; Song, Bokai; Nimgaonkar, Ila; Hrebikova, Gabriela; Contreras, Jorge E; Ploss, Alexander

    2017-01-31

    Hepatitis E virus (HEV) is the leading cause of enterically transmitted viral hepatitis globally. Of HEV's three ORFs, the function of ORF3 has remained elusive. Here, we demonstrate that via homophilic interactions ORF3 forms multimeric complexes associated with intracellular endoplasmic reticulum (ER)-derived membranes. HEV ORF3 shares several structural features with class I viroporins, and the function of HEV ORF3 can be maintained by replacing it with the well-characterized viroporin influenza A virus (IAV) matrix-2 protein. ORF3's ion channel function is further evidenced by its ability to mediate ionic currents when expressed in Xenopus laevis oocytes. Furthermore, we identified several positions in ORF3 critical for its formation of multimeric complexes, ion channel activity, and, ultimately, release of infectious particles. Collectively, our data demonstrate a previously undescribed function of HEV ORF3 as a viroporin, which may serve as an attractive target in developing direct-acting antivirals.

  10. Analysis of conjugated linoleic acid-enriched triacylglycerol mixtures by isocratic silver-ion high-performance liquid chromatography.

    Science.gov (United States)

    Adlof, R O; Menzel, A; Dorovska-Taran, V

    2002-04-12

    Silver-ion HPLC (Ag-HPLC) was applied to the fractionation of a triacylglycerol (TAG) sample enriched (>80%) with conjugated linoleic acid (CLA). After conversion of the TAGs to fatty acid methyl esters using sodium methoxide in methanol, Ag-HPLC (dual-column; isocratic solvent system of 0.1% acetonitrile in hexane; UV detection at 233 nm) was used to determine the CLA isomer distribution (50:50 mixture of 9c 11t- and 10t,12c-18:2). Three or four Ag-HPLC columns connected in series (0.6-1.0% acetonitrile in hexane as solvent; UV detection at 206 nm) were used to analyze the sample in TAG form. Elution times for CLA-enriched TAGs averaged 30 min or less. Isocratic solvent conditions were used to eliminate the solvent equilibration times (often 30 min or more) required between sample injections when solvent programming is used. The ratio of TAGs containing three vs. only two CLA molecules was found to be approximately 3 to 1. Ag-HPLC has thus been shown to be a useful method for rapidly analyzing not only CLA isomers as esters, but also in the TAG form.

  11. Comment on "A re-assessment of the safety of silver in household water treatment: rapid systematic review of mammalian in vivo genotoxicity studies".

    Science.gov (United States)

    Lantagne, Daniele; Rayner, Justine; Mittelman, Anjuliee; Pennell, Kurt

    2017-11-13

    We wish to thank Fewtrell, Majuru, and Hunter for their article highlighting genotoxic risks associated with the use of particulate silver for primary drinking water treatment. The recent promotion of colloidal silver products for household water treatment in developing countries is problematic due to previously identified concerns regarding manufacturing quality and questionable advertising practices, as well as the low efficiency of silver nanoparticles to treat bacteria, viruses, and protozoa in source waters. However, in the conclusion statement of the manuscript, Fewtrell et al. state, "Before colloidal Ag or AgNP are used in filter matrices for drinking water treatment, consideration needs to be given to how much silver is likely to be released from the matrix during the life of the filter." Unfortunately, it appears Fewtrell et al. were unaware that studies of silver nanoparticle and silver ion elution from ceramic filters manufactured and used in developing countries have already been completed. These existing studies have found that: 1) silver ions, not silver nanoparticles, are eluted from ceramic filters treated with silver nanoparticles or silver nitrate; and, 2) silver ions have not been shown to be genotoxic. Thus, the existing recommendation of applying silver nanoparticles to ceramic filters to prevent biofilm formation within the filter and improve microbiological efficacy should still be adhered to, as there is no identified risk to people who drink water from ceramic filters treated with silver nanoparticles or silver nitrate. We note that efforts should continue to minimize exposure to silver nanoparticles (and silica) to employees in ceramic filter factories in collaboration with the organizations that provide technical assistance to ceramic filter factories.

  12. Silver nanoparticles deposited on amine-functionalized silica spheres and their amalgamation-based spectral and colorimetric detection of Hg(II) ions

    Energy Technology Data Exchange (ETDEWEB)

    Rameshkumar, Perumal; Manivannan, Shanmugam; Ramaraj, Ramasamy, E-mail: ramarajr@yahoo.com [Madurai Kamaraj University, Centre for Photoelectrochemistry, School of Chemistry (India)

    2013-05-15

    A facile synthetic method to decorate amine-functionalized silica spheres (SiO{sub 2}) by silver nanoparticles (Ag NPs) is reported. The transmission electron microscopic (TEM) images showed that spherical Ag NPs with an average particle size of 14 nm were deposited on 250 nm-sized SiO{sub 2} spheres (SiO{sub 2}/Ag NPs). The spectral and colorimetric detection of Hg(II) ions were carried out using the synthesized SiO{sub 2}/Ag NPs with an experimental detection limit of 5 {mu}M. It was found that the addition of Hg(II) ions (150 {mu}M) into the solution of SiO{sub 2}/Ag NPs completely quenched the SPR band of the Ag NPs due to the formation of anisotropic Ag amalgam crystals (AgHg). The selective detection of Hg(II) ions by SiO{sub 2}/Ag NPs in the presence of other environmentally relevant metal ions was also demonstrated using spectral and colorimetric methods.Graphical abstractAmine-functionalized silica spheres are decorated by in situ formation of silver nanoparticles and their spectral and colorimetric detection of Hg(II) ions is reported.

  13. Synthesis of silver nanoparticles stabilized with C-phycocyanin and for fluorimetric detection of copper ions

    Science.gov (United States)

    Wei, Nana; Hou, Yanhua; Lu, Zongbao; Yu, Huatong; Wang, Quanfu

    2018-01-01

    In this study, C-phycocyanin as protective agent, AgNO3 as raw material and NaBH4 as reducing agent synthesized C-phycocyanin-Ag nanoparticles (PC-AgNPs). The synthesis conditions of PC-AgNPs were determined by optimization. The maximum UV absorption peak of PC-AgNPs at 400 nm. The fluorescence excitation wavelength was 580 nm and the emission wavelength was 625 nm. PC-AgNPs was spherical in transmission electron microscope and the particles sizes were about 10-25 nm. In addition, fluorescence quenching was observed after adding copper ions to PC-AgNPs, which indicated that PC-AgNPs has potential applications in the detection of copper ions in diverse water environment.

  14. Use of carbon paste electrodes for the voltammetric detection of silver leached from the oxidative dissolution of silver nanoparticles

    Science.gov (United States)

    Mullaugh, Katherine M.; Pearce, Olivia M.

    2017-04-01

    The widespread use of silver nanoparticles (Ag NPs) in consumer goods has raised concerns about the release of silver in environmental waters. Of particular concern is the oxidative dissolution of Ag NPs to release Ag+ ions, which are highly toxic to many aquatic organisms. Here, we have investigated the application of differential pulse stripping voltammetry (DPSV) with carbon paste electrodes (CPEs) in monitoring the oxidation of Ag NPs. Using a commercially available, unmodified carbon paste and 60-s deposition times, a detection limit of 3 nM Ag+ could be achieved. We demonstrate its selectivity for free Ag+ ions over Ag nanoparticles, allowing for analysis of the oxidation of Ag NPs without the need for separation of ions and nanoparticles prior to analysis. We applied this approach to investigate the effect of pH in the oxidative dissolution of Ag NPs, demonstrating the usefulness of CPEs in studies of this type.

  15. Use of carbon paste electrodes for the voltammetric detection of silver leached from the oxidative dissolution of silver nanoparticles

    International Nuclear Information System (INIS)

    Mullaugh, Katherine M.; Pearce, Olivia M.

    2017-01-01

    The widespread use of silver nanoparticles (Ag NPs) in consumer goods has raised concerns about the release of silver in environmental waters. Of particular concern is the oxidative dissolution of Ag NPs to release Ag"+ ions, which are highly toxic to many aquatic organisms. Here, we have investigated the application of differential pulse stripping voltammetry (DPSV) with carbon paste electrodes (CPEs) in monitoring the oxidation of Ag NPs. Using a commercially available, unmodified carbon paste and 60-s deposition times, a detection limit of 3 nM Ag"+ could be achieved. We demonstrate its selectivity for free Ag"+ ions over Ag nanoparticles, allowing for analysis of the oxidation of Ag NPs without the need for separation of ions and nanoparticles prior to analysis. We applied this approach to investigate the effect of pH in the oxidative dissolution of Ag NPs, demonstrating the usefulness of CPEs in studies of this type.

  16. Use of carbon paste electrodes for the voltammetric detection of silver leached from the oxidative dissolution of silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Mullaugh, Katherine M., E-mail: mullaughkm@cofc.edu; Pearce, Olivia M. [College of Charleston, Department of Chemistry & Biochemistry (United States)

    2017-04-15

    The widespread use of silver nanoparticles (Ag NPs) in consumer goods has raised concerns about the release of silver in environmental waters. Of particular concern is the oxidative dissolution of Ag NPs to release Ag{sup +} ions, which are highly toxic to many aquatic organisms. Here, we have investigated the application of differential pulse stripping voltammetry (DPSV) with carbon paste electrodes (CPEs) in monitoring the oxidation of Ag NPs. Using a commercially available, unmodified carbon paste and 60-s deposition times, a detection limit of 3 nM Ag{sup +} could be achieved. We demonstrate its selectivity for free Ag{sup +} ions over Ag nanoparticles, allowing for analysis of the oxidation of Ag NPs without the need for separation of ions and nanoparticles prior to analysis. We applied this approach to investigate the effect of pH in the oxidative dissolution of Ag NPs, demonstrating the usefulness of CPEs in studies of this type.

  17. Sustained release of antibiotic complexed by multivalent ion: in vitro and in vivo study for the treatment of peritonitis.

    Science.gov (United States)

    Na, Seung Yeon; Oh, Se Heang; Kim, Tae Ho; Yoon, Jin A; Lee, In Soo; Lee, Jin Ho

    2014-12-10

    The main aims of this study are (i) the development of an antibiotic complexed with multivalent ion, which can allow sustained release of the antibiotic without any additional matrix or difficult process and (ii) the feasibility study of the ion-complexed antibiotic as a therapeutic technique for peritonitis treatment. An ion-complexed antibiotic is prepared by simple mixing of two aqueous solutions containing an ionized (water-soluble) drug (tetracycline) and a multivalent counter ionic compound. The ion-complexed antibiotic shows a continuous release of the antibiotic up to 21 days, and thus prolonged anti-bacterial effect by gradual ionic exchange between the multivalent ions in the complex and same-charged monovalent ions in surrounding medium. From the in vivo animal study using a cecum perforated peritonitis mouse model, the ion-complexed antibiotic group shows sufficient anti-bacterial effect and thus effectively treat the peritonitis because of the extermination of the contaminated enteric bacteria in the peritoneum during wound healing of injury cecum (by the sustained release of antibiotic from the ion complex). These results suggest that the ion-complexed antibiotic system may be promising for the effective treatment of the peritonitis caused by frequent gastrointestinal defect in clinical fields. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. MECHANISMS CONTROLLING Ca ION RELEASE FROM SOL-GEL DERIVED IN SITU APATITE-SILICA NANOCOMPOSITE POWDER

    Directory of Open Access Journals (Sweden)

    Seyed Mohsen Latifi

    2015-03-01

    Full Text Available Ca ion release from bioactive biomaterials could play an important role in their bioactivity and osteoconductivity properties. In order to improve hydroxyapatite (HA dissolution rate, in situ apatite-silica nanocomposite powders with various silica contents were synthesized via sol-gel method and mechanisms controlling the Ca ion release from them were investigated. Obtained powders were characterized by X-ray diffraction (XRD and transmission electron spectroscopy (TEM techniques, acid dissolution test, and spectroscopy by atomic absorption spectrometer (AAS. Results indicated the possible incorporation of (SiO44- into the HA structure and tendency of amorphous silica to cover the surface of HA particles. However, 20 wt. % silica was the lowest amount that fully covered HA particles. All of the nanocomposite powders showed more Ca ion release compared with pure HA, and HA - 10 wt. % silica had the highest Ca ion release. The crystallinity, the crystallite size, and the content of HA, along with the integrity, thickness, and ion diffusion possibility through the amorphous silica layer on the surface of HA, were factors that varied due to changes in the silica content and were affected the Ca ion release from nanocomposite powders.

  19. The load and release characteristics on a strong cationic ion-exchange fiber: kinetics, thermodynamics, and influences.

    Science.gov (United States)

    Yuan, Jing; Gao, Yanan; Wang, Xinyu; Liu, Hongzhuo; Che, Xin; Xu, Lu; Yang, Yang; Wang, Qifang; Wang, Yan; Li, Sanming

    2014-01-01

    Ion-exchange fibers were different from conventional ion-exchange resins in their non-cross-linked structure. The exchange was located on the surface of the framework, and the transport resistance reduced significantly, which might mean that the exchange is controlled by an ionic reaction instead of diffusion. Therefore, this work aimed to investigate the load and release characteristics of five model drugs with the strong cationic ion-exchange fiber ZB-1. Drugs were loaded using a batch process and released in United States Pharmacopoeia (USP) dissolution apparatus 2. Opposing exchange kinetics, suitable for the special structure of the fiber, were developed for describing the exchange process with the help of thermodynamics, which illustrated that the load was controlled by an ionic reaction. The molecular weight was the most important factor to influence the drug load and release rate. Strong alkalinity and rings in the molecular structures made the affinity between the drug and fiber strong, while logP did not cause any profound differences. The drug-fiber complexes exhibited sustained release. Different kinds and concentrations of counter ions or different amounts of drug-fiber complexes in the release medium affected the release behavior, while the pH value was independent of it. The groundwork for in-depth exploration and further application of ion-exchange fibers has been laid.

  20. Nitrogen doped graphene - Silver nanowire hybrids: An excellent anode material for lithium ion batteries

    Science.gov (United States)

    Nair, Anju K.; Elizabeth, Indu; S, Gopukumar; Thomas, Sabu; M. S, Kala; Kalarikkal, Nandakumar

    2018-01-01

    We present an in-situ polyol assisted synthesis approach for the preparation of silver nanowires (AgNW) over the nitrogen doped graphene (NG) sheets and has been tested as a viable LIBs anode material for the first time. The use of NG serves as nucleation sites, thereby facilitating the growth of AgNWs. The specific material design of the as-prepared NG-AgNW hybrids involves some advantages, including a continuous AgNW-graphene conducting network. Since AgNWs are electrically conductive, it provides an electrical contact with NG sheets which can effectively help the charge transport process and limit the variations in volume during the lithiation/de-lithiation processes. Apart from this, the insertion of metallic Ag nanowires into a percolated NG network increases the interlayer distance of NG sheets and prevent its restacking. Moreover, the more porous nature of the hybrid structure accommodating the large volume changes of AgNWs. As an anode material for LIBs, the NG-AgNW hybrid displays a remarkable initial discharge capacity of 1215 mAh g-1 and attains a stable capacity of 724 mAh g-1 at a current density of 100 mA g-1 after 50 cycles. The electrode exhibits a stable reversible capacity of 714, 634, 550 and 464 mA h g-1 at 0.1, 0.2, 0.5, 1 Ag-1 respectively. The reversible capacity (710 mAh g-1) at 0.1 Ag-1 is recovered after the cycling at various current densities confirming outstanding rate performance of the material. In addition, the coulombic efficiency, the NG-AgNW anode retains nearly 99% after the second cycle, further indicating its excellent reversibility. The hybrid material exhibits better cycling stability, greater rate capability, capacity retention and superior reversible capacity than that of bare AgNW and NG sheets. Our smart design will pave way for the development of efficient electrode materials for high capacity and long cycle life LIBs.

  1. Systemic levels of metallic ions released from orthodontic mini-implants.

    Science.gov (United States)

    de Morais, Liliane Siqueira; Serra, Glaucio Guimarães; Albuquerque Palermo, Elisabete Fernandes; Andrade, Leonardo Rodrigues; Müller, Carlos Alberto; Meyers, Marc André; Elias, Carlos Nelson

    2009-04-01

    Orthodontic mini-implants are a potential source of metallic ions to the human body because of the corrosion of titanium (Ti) alloy in body fluids. The purpose of this study was to gauge the concentration of Ti, aluminum (Al), and vanadium (V), as a function of time, in the kidneys, livers, and lungs of rabbits that had Ti-6Al-4V alloy orthodontic mini-implants placed in their tibia. Twenty-three New Zealand rabbits were randomly divided into 4 groups: control, 1 week, 4 weeks, and 12 weeks. Four orthodontic mini-implants were placed in the left proximal tibia of 18 rabbits. Five control rabbits had no orthodontic mini-implants. After 1, 4, and 12 weeks, the rabbits were killed, and the selected tissues were extracted and prepared for analysis by graphite furnace atomic absorption spectrophotometry. Low amounts of Ti, Al, and V were detectable in the 1-week, 4-weeks, and 12-weeks groups, confirming that release of these metals from the mini-implants occurs, with diffusion and accumulation in remote organs. Despite the tendency of ion release when using the Ti alloy as orthodontic mini-implants, the amounts of metals detected were significantly below the average intake of these elements through food and drink and did not reach toxic concentrations.

  2. The Extracellular Domain of Human High Affinity Copper Transporter (hNdCTR1), Synthesized by E. coli Cells, Chelates Silver and Copper Ions In Vivo.

    Science.gov (United States)

    Sankova, Tatiana P; Orlov, Iurii A; Saveliev, Andrey N; Kirilenko, Demid A; Babich, Polina S; Brunkov, Pavel N; Puchkova, Ludmila V

    2017-11-03

    There is much interest in effective copper chelators to correct copper dyshomeostasis in neurodegenerative and oncological diseases. In this study, a recombinant fusion protein for expression in Escherichia coli cells was constructed from glutathione-S-transferase (GST) and the N-terminal domain (ectodomain) of human high affinity copper transporter CTR1 (hNdCTR1), which has three metal-bound motifs. Several biological properties of the GST-hNdCTR1 fusion protein were assessed. It was demonstrated that in cells, the protein was prone to oligomerization, formed inclusion bodies and displayed no toxicity. Treatment of E. coli cells with copper and silver ions reduced cell viability in a dose- and time-dependent manner. Cells expressing GST-hNdCTR1 protein demonstrated resistance to the metal treatments. These cells accumulated silver ions and formed nanoparticles that contained AgCl and metallic silver. In this bacterial population, filamentous bacteria with a length of about 10 µm were often observed. The possibility for the fusion protein carrying extracellular metal binding motifs to integrate into the cell's copper metabolism and its chelating properties are discussed.

  3. The Extracellular Domain of Human High Affinity Copper Transporter (hNdCTR1, Synthesized by E. coli Cells, Chelates Silver and Copper Ions In Vivo

    Directory of Open Access Journals (Sweden)

    Tatiana P. Sankova

    2017-11-01

    Full Text Available There is much interest in effective copper chelators to correct copper dyshomeostasis in neurodegenerative and oncological diseases. In this study, a recombinant fusion protein for expression in Escherichia coli cells was constructed from glutathione-S-transferase (GST and the N-terminal domain (ectodomain of human high affinity copper transporter CTR1 (hNdCTR1, which has three metal-bound motifs. Several biological properties of the GST-hNdCTR1 fusion protein were assessed. It was demonstrated that in cells, the protein was prone to oligomerization, formed inclusion bodies and displayed no toxicity. Treatment of E. coli cells with copper and silver ions reduced cell viability in a dose- and time-dependent manner. Cells expressing GST-hNdCTR1 protein demonstrated resistance to the metal treatments. These cells accumulated silver ions and formed nanoparticles that contained AgCl and metallic silver. In this bacterial population, filamentous bacteria with a length of about 10 µm were often observed. The possibility for the fusion protein carrying extracellular metal binding motifs to integrate into the cell’s copper metabolism and its chelating properties are discussed.

  4. Optical properties of multicomponent antimony-silver nanoclusters formed in silica by sequential ion implantation

    International Nuclear Information System (INIS)

    Zuhr, R.A.

    1995-11-01

    The linear and nonlinear optical properties of nanometer dimension metal colloids embedded in a dielectric depend explicitly on the electronic structure of the metal nanoclusters. The ability to control the electronic structure of the nanoclusters may make it possible to tailor the optical properties for enhanced performance. By sequential implantation of different metal ion species multi-component nanoclusters can be formed with significantly different optical properties than single element metal nanoclusters. The authors report the formation of multi-component Sb/Ag nanoclusters in silica by sequential implantation of Sb and Ag. Samples were implanted with relative ratios of Sb to Ag of 1:1 and 3:1. A second set of samples was made by single element implantations of Ag and Sb at the same energies and doses used to make the sequentially implanted samples. All samples were characterized using RBS and both linear and nonlinear optical measurements. The presence of both ions significantly modifies the optical properties of the composites compared to the single element nanocluster glass composites. In the sequentially implanted samples the optical density is lower, and the strong surface plasmon resonance absorption observed in the Ag implanted samples is not present. At the same time the nonlinear response of the these samples is larger than for the samples implanted with Sb alone, suggesting that the addition of Ag can increase the nonlinear response of the Sb particles formed. The results are consistent with the formation of multi-component Sb/Ag colloids

  5. A flow injection analysis system for monitoring silver (I) ion and iodine residuals in recycled water from recovery systems used for spaceflight

    Energy Technology Data Exchange (ETDEWEB)

    Williamson, Jill P.; Emmert, Gary L., E-mail: gemmert@memphis.edu

    2013-08-20

    Graphical abstract: A device for on-line monitoring of the water disinfectants silver (I) ion or iodine in recycled water is presented. Simply change the reagents and the sample loop volume to switch between silver ion and iodine configurations. -- Highlights: •Automated FIA device for monitoring Ag{sup +} or I{sub 2} residuals in recycled drinking water. •Method detection limits of Ag{sup +} of 52 μg L{sup −1} and I{sub 2} of 2 μg L{sup −1}. •Mean % recoveries for Ag{sup +} of 104 ± 1% and for I{sub 2} of 96.2 ± 0.1%. •% relative standard deviation estimates for Ag{sup +} of 1.4% and for I{sub 2} of 5.7%. •Bias measurements agreed to 11.3 μg L{sup −1} for Ag{sup +} and to 27.3 μg L{sup −1} for I{sub 2}. -- Abstract: A laboratory-built flow injection analyzer is reported for monitoring the drinking water disinfectants silver (I) ion and iodine in water produced from NASA's water recovery system. This analyzer uses spectrophotometric detection with a custom made 10 cm optical flow cell. Optimization and interference studies are discussed for the silver (I) ion configuration. Subsequent results using the silver (I) configuration with minor modifications and alternative reagents gave promising results for iodine determinations as well. The estimated MDL values for Ag{sup +} and I{sub 2} are 52 μg L{sup −1} Ag{sup +} and 2 μg L{sup −1} I{sub 2}; the mean percent recoveries were 104% and 96.2% for Ag{sup +} and I{sub 2} respectfully; and percent relative standard deviations were estimated at 1.4% for Ag{sup +} and 5.7% for I{sub 2}. The agreement of this potentially multifunctional analyzer to reference methods for each respective water disinfectant is measured using Bland–Altman analysis as well as more traditional estimates.

  6. pH-sensitive nanocarrier based on gold/silver core-shell nanoparticles decorated multi-walled carbon manotubes for tracing drug release in living cells.

    Science.gov (United States)

    Chen, Peng; Wang, Zhuyuan; Zong, Shenfei; Zhu, Dan; Chen, Hui; Zhang, Yizhi; Wu, Lei; Cui, Yiping

    2016-01-15

    We fabricate a multifunctional nanocarrier based on multi-walled carbon nanotubes (MWCNTs) decorated with gold/silver core-shell nanoparticles (Au@Ag NPs) and fluorescein isothiocyanate (FITC) for tracking the intracellular drug release process. In the demonstrated nanocarrier, the Au@Ag NPs adsorbed on the surface of MWCNTs were labeled with the pH-dependent SERS reporter 4-Mercaptobenzoic acid (4MBA) for SERS based pH sensing. FITC was conjugated on MWCNTs to provide fluorescence signal for tracing the MWCNTs. Fluorescent doxorubicin (DOX) was used as the model drug which can be loaded onto MWCNTs via π-π stacking and released from the MWCNTs under acidic condition. By detecting the SERS spectrum of 4MBA, the pH value around the nanocarrier could be monitored. Besides, by tracing the fluorescence of FITC and DOX, we can also investigate the drug release process in cells. Experimental results show that the proposed nanocarrier retained a well pH-sensitive performance in living cells, and the DOX detached from MWCNTs inside the lysosomes and entered into the cytoplasm with the MWCNTs being left in lysosomes. To further investigate the drug release dynamics, 2-D color-gradient pH mapping were plotted, which were calculated from the SERS spectra of 4MBA. The detailed release process and carrier distribution have been recorded as environmental pH changes during cell endocytosis. Furthermore, we also confirmed that the proposed nanocarrier has a good biocompatibility. It indicates that the designed nanocarrier have a great potential in intraceable drug delivery, cancer cells imaging and pH monitoring. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Effects of Test Paper Drying and Reaction Periods on Silver Ion-Arsine Complex Colour Development for a Simple and Rapid Arsenic (V) Determination

    International Nuclear Information System (INIS)

    Khim, O.K.; Wan Md Zin Wan Yunus; Abdul Ghapor Hussin; Mansor Ahmad; Ahmad Farid Mohd Azmi

    2015-01-01

    Arsenic is a toxic element that exists in different forms in nature and can be accumulated by various biota and environmental media. Current techniques for the environmental monitoring of arsenic are usually sophisticated, time consuming and inappropriate for on-site analyses. We are developing a simple and rapid colorimetric quantitative method based on a colour complex formed by silver ion impregnated on a filter paper with arsine gas produced from arsenic ion reduction by hydrogen generated from zinc and sulfamic acid reaction in the sample. In this report we describe effects of drying of the silver ion impregnated filter paper and exposing period of this test paper to the arsine gas. The data obtained are digitized and used to develop a model for arsenic (V) ion estimation. The study reveals that when 4.0 g of sulfamic acid and 2.0 g of zinc powder are used to reduce 50 ml of arsenic solution sample, the drying and exposure periods needed are 20 seconds and 10 minutes, respectively. The best fitted model that relates arsenic (V) concentration (Ac) and the red colour intensity value (R) is Ac =120.1 - 1.071R. This model can accurately estimate the arsenic (V) concentration from 0 to 100 μg/l. (author)

  8. Pyrrolo-dC Metal-Mediated Base Pairs in the Reverse Watson-Crick Double Helix: Enhanced Stability of Parallel DNA and Impact of 6-Pyridinyl Residues on Fluorescence and Silver-Ion Binding.

    Science.gov (United States)

    Yang, Haozhe; Mei, Hui; Seela, Frank

    2015-07-06

    Reverse Watson-Crick DNA with parallel-strand orientation (ps DNA) has been constructed. Pyrrolo-dC (PyrdC) nucleosides with phenyl and pyridinyl residues linked to the 6 position of the pyrrolo[2,3-d]pyrimidine base have been incorporated in 12- and 25-mer oligonucleotide duplexes and utilized as silver-ion binding sites. Thermal-stability studies on the parallel DNA strands demonstrated extremely strong silver-ion binding and strongly enhanced duplex stability. Stoichiometric UV and fluorescence titration experiments verified that a single (2py) PyrdC-(2py) PyrdC pair captures two silver ions in ps DNA. A structure for the PyrdC silver-ion base pair that aligns 7-deazapurine bases head-to-tail instead of head-to-head, as suggested for canonical DNA, is proposed. The silver DNA double helix represents the first example of a ps DNA structure built up of bidentate and tridentate reverse Watson-Crick base pairs stabilized by a dinuclear silver-mediated PyrdC pair. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Anomeric 2'-Deoxycytidines and Silver Ions: Hybrid Base Pairs with Greatly Enhanced Stability and Efficient DNA Mismatch Detection with α-dC.

    Science.gov (United States)

    Guo, Xiurong; Seela, Frank

    2017-09-04

    α-d-Nucleosides are rare in nature but can develop fascinating properties when incorporated into DNA. This work reports on the first silver-mediated base pair constructed from two anomeric nucleosides: α-dC and β-dC. The hybrid base pair was integrated into the DNA and DNA/RNA double helix. A 12-mer duplex with α-dC and β-dC pair exhibits a higher thermal stability (T m =43 °C) than that incorporating the β-dC-Ag + -β-dC homo pair (T m =34 °C). Furthermore, α-dC shows excellent mismatch discrimination for DNA single nucleotide polymorphism (SNP). All four SNPs were identified on the basis of large T m value differences measured in the presence of silver ions. High resolution melting was not required. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Electronic stopping powers for fluorine ions in 19F+-implanted silver gallium diselenide

    International Nuclear Information System (INIS)

    Liu Xiangdong; Xia Yueyuan; Li Feng; Lu Qingming; Huang Boda

    2004-01-01

    Electronic stopping powers for 80-350 keV 19 F ions in AgGaSe 2 were obtained by range measurement. Depth profiles of 19 F in AgGaSe 2 were measured by using the 19 F(p,αγ) 16 O resonant nuclear reaction at E R =872.1 keV. A proper convolution calculation method was used to extract the true distribution of fluorine from the experimental excitation yield curves. The electronic stopping powers were derived through fitting the projected range distributions, simulated by using the TRIM/XLL code, to the experimentally measured range distributions. The electronic stopping cross-sections were compared with those obtained from Monte Carlo simulation codes

  11. Electronic stopping powers for fluorine ions in {sup 19}F{sup +}-implanted silver gallium diselenide

    Energy Technology Data Exchange (ETDEWEB)

    Liu Xiangdong E-mail: xdliu@sdu.edu.cn; Xia Yueyuan; Li Feng; Lu Qingming; Huang Boda

    2004-08-01

    Electronic stopping powers for 80-350 keV {sup 19}F ions in AgGaSe{sub 2} were obtained by range measurement. Depth profiles of {sup 19}F in AgGaSe{sub 2} were measured by using the {sup 19}F(p,{alpha}{gamma}){sup 16}O resonant nuclear reaction at E{sub R}=872.1 keV. A proper convolution calculation method was used to extract the true distribution of fluorine from the experimental excitation yield curves. The electronic stopping powers were derived through fitting the projected range distributions, simulated by using the TRIM/XLL code, to the experimentally measured range distributions. The electronic stopping cross-sections were compared with those obtained from Monte Carlo simulation codes.

  12. Luminescence quenching versus enhancement in WO3-NaPO3 glasses doped with trivalent rare earth ions and containing silver nanoparticles

    Science.gov (United States)

    Dousti, M. Reza; Poirier, Gael Y.; Amjad, Raja J.; de Camargo, Andrea S. S.

    2016-10-01

    We report on the influence of silver nanoparticles (NPs) on the luminescence behavior of trivalent rare earth (RE) ion doped tungsten-phosphate glasses. In order to induce the growth of NPs, the as-prepared glass samples containing silver atoms, are exposed to heat-treatment above the glass transition temperature. The surface plasmon resonance band of the Ag NPs is observed in the visible range around 420 and 537 nm in the glasses with low and high tungsten content, respectively. Such difference in spectral shift of the plasmon band is attributed to the difference in the refractive index of the two studied glass compositions. Heat-treatment results in the general increase in number of NPs, while in the case of glasses with low tungsten content, it also imposes a shift to the Ag plasmon band. The NPs size distribution (4-10 nm) was determined in good agreement with the values obtained by using Mie theory and by transmission electron microscopy. The observed quenching in the visible luminescence of glasses doped with Eu3+, Tb3+ or Er3+is attributed to energy transfer from the RE ions to Ag species, while an enhanced near-infrared emission in Er3+ doped glasses is discussed in terms of the chemical contribution of silver, rather than the most commonly claimed enhancement of localized field or energy transfer from silver species to Er3+. The results are supported by the lifetime measurements. We believe that this study gives further insight and in-depth exploration of the somewhat controversial discussions on the influence of metallic NPs plasmonic effects in RE-doped glasses.

  13. Metal ion-assisted self-assembly of complexes for controlled and sustained release of minocycline for biomedical applications

    International Nuclear Information System (INIS)

    Zhang, Zhiling; Wang, Zhicheng; Nong, Jia; Nix, Camilla A; Zhong, Yinghui; Ji, Hai-Feng

    2015-01-01

    This study reports the development of novel drug delivery complexes self-assembled by divalent metal ion-assisted coacervation for controlled and sustained release of a hydrophilic small drug molecule minocycline hydrochloride (MH). MH is a multifaceted agent that has demonstrated therapeutic effects in infection, inflammation, tumor, as well as cardiovascular, renal, and neurological disorders due to its anti-microbial, anti-inflammatory, and cytoprotective properties. However, the inability to translate the high doses used in experimental animals to tolerable doses in human patients limits its clinical application. Localized delivery can potentially expose the diseased tissue to high concentrations of MH that systemic delivery cannot achieve, while minimizing the side effects from systemic exposure. The strong metal ion binding-assisted interaction enabled high drug entrapment and loading efficiency, and stable long term release for more than 71 d. Released MH demonstrated potent anti-biofilm, anti-inflammatory, and neuroprotective activities. Furthermore, MH release from the complexes is pH-sensitive as the chelation between minocycline and metal ions decreases with pH, allowing ‘smart’ drug release in response to the severity of pathology-induced tissue acidosis. This novel metal ion binding-mediated drug delivery mechanism can potentially be applied to other drugs that have high binding affinity for metal ions and may lead to the development of new delivery systems for a variety of drugs. (paper)

  14. Adduct formation of ionic and nanoparticular silver with amino acids and glutathione

    Science.gov (United States)

    Blaske, Franziska; Stork, Lisa; Sperling, Michael; Karst, Uwe

    2013-09-01

    To investigate the interaction of ionic and nanoparticular silver with amino acids and small peptides, an electrospray ionization time-of-flight mass spectrometry method was developed. Monomeric and oligomeric silver adducts were formed with amino acids including cysteine (Cys), methionine, histidine, lysine, or the tripeptide glutathione (GSH). The obtained spectra for ionic silver show clusters in different ratios between Ag+ and the reaction partners (X) including [Ag n X m - ( n + 1)H]- ( n = 1-4, m = 1-3). Regarding Cys, adduct clusters up to n = 5 and m = 4 were observed as well. Considering silver-GSH interactions, even doubly charged oligomers occur generating [Ag( a + 1)GSH a - ( a + 3)H]2- ( a = 5-7) and [Ag b GSH b - ( b + 2)H]2- ( b = 4-8) ions. 1H NMR data of free GSH compared to that after treatment with Ag+ confirm sulfur-metal interactions due to changing chemical shifts for the protons located adjacent to the thiol group. Density functional theory calculations for silver-GSH clusters may explain the formation of experimentally recorded large clusters due to cooperative effects between silver and carboxylic acid side chains. Both sets of experiments indicate the presence of these adducts in the liquid phase. For silver nanoparticles, the respective data confirm the release of silver ions and the subsequent adduct formation.

  15. Adduct formation of ionic and nanoparticular silver with amino acids and glutathione

    Energy Technology Data Exchange (ETDEWEB)

    Blaske, Franziska; Stork, Lisa; Sperling, Michael; Karst, Uwe, E-mail: uk@uni-muenster.de [University of Muenster, Institute of Inorganic and Analytical Chemistry (Germany)

    2013-09-15

    To investigate the interaction of ionic and nanoparticular silver with amino acids and small peptides, an electrospray ionization time-of-flight mass spectrometry method was developed. Monomeric and oligomeric silver adducts were formed with amino acids including cysteine (Cys), methionine, histidine, lysine, or the tripeptide glutathione (GSH). The obtained spectra for ionic silver show clusters in different ratios between Ag{sup +} and the reaction partners (X) including [Ag{sub n}X{sub m} - (n + 1)H]{sup -} (n = 1-4, m = 1-3). Regarding Cys, adduct clusters up to n = 5 and m = 4 were observed as well. Considering silver-GSH interactions, even doubly charged oligomers occur generating [Ag{sub (a+1)}GSH{sub a} - (a + 3)H]{sup 2-} (a = 5-7) and [Ag{sub b}GSH{sub b} - (b + 2)H]{sup 2-} (b = 4-8) ions. {sup 1}H NMR data of free GSH compared to that after treatment with Ag{sup +} confirm sulfur-metal interactions due to changing chemical shifts for the protons located adjacent to the thiol group. Density functional theory calculations for silver-GSH clusters may explain the formation of experimentally recorded large clusters due to cooperative effects between silver and carboxylic acid side chains. Both sets of experiments indicate the presence of these adducts in the liquid phase. For silver nanoparticles, the respective data confirm the release of silver ions and the subsequent adduct formation.

  16. Laser cladding of stainless steel with a copper-silver alloy to generate surfaces of high antimicrobial activity

    Science.gov (United States)

    Hans, Michael; Támara, Juan Carlos; Mathews, Salima; Bax, Benjamin; Hegetschweiler, Andreas; Kautenburger, Ralf; Solioz, Marc; Mücklich, Frank

    2014-11-01

    Copper and silver are used as antimicrobial agents in the healthcare sector in an effort to curb infections caused by bacteria resistant to multiple antibiotics. While the bactericidal potential of copper and silver alone are well documented, not much is known about the antimicrobial properties of copper-silver alloys. This study focuses on the antibacterial activity and material aspects of a copper-silver model alloy with 10 wt% Ag. The alloy was generated as a coating with controlled intermixing of copper and silver on stainless steel by a laser cladding process. The microstructure of the clad was found to be two-phased and in thermal equilibrium with minor Cu2O inclusions. Ion release and killing of Escherichia coli under wet conditions were assessed with the alloy, pure silver, pure copper and stainless steel. It was found that the copper-silver alloy, compared to the pure elements, exhibited enhanced killing of E. coli, which correlated with an up to 28-fold increased release of copper ions. The results show that laser cladding with copper and silver allows the generation of surfaces with enhanced antimicrobial properties. The process is particularly attractive since it can be applied to existing surfaces.

  17. Ion dynamics in AgI doped silver selenium-tellurite mixed former glasses

    Science.gov (United States)

    Palui, A.; Ghosh, A.

    2017-03-01

    The ionic conductivity and the conductivity spectra of the glass compositions xAgI-(1-x)[yAg2O-(1-y)(0.5SeO2-0.5TeO2)] have been studied at different temperatures The activation energy for the dc conduction has been analyzed using the Anderson-Stuart model, and a correlation between the dc conductivity and the doorway radius has been obtained. We have analyzed the conductivity spectra using the random free-energy barrier model, taking into account the contribution of electrode polarization. It is observed that the Barton-Nakajima-Namikawa relation between the conductivity and the relaxation time is valid for these glasses. The time-temperature superposition principle has been verified using the scaling of the conductivity spectra in the framework of the random barrier model. The charge carrier density, obtained from the Nernst-Einstein relation, is found to be almost independent of temperature, but dependent weakly on composition. We have also studied the influence of the modification of the network structure of these glasses on ion migration and correlated the conductivity with the relative strength of the structural units.

  18. Silver/carbon nanotube hybrids: A novel conductive network for high-rate lithium ion batteries

    International Nuclear Information System (INIS)

    Zhou, Fangdong; Qiu, Kehui; Peng, Gongchang; Xia, Li

    2015-01-01

    LiNi 1/3 Co 1/3 Mn 1/3 O 2 /Ag composite cathodes are synthesized by a thermal decomposition method and multi-walled carbon nanotubes are uniformly introduced into the composites through ball mixing. A composite electrically conductive network consisting of CNTs and Ag is obtained to improve the conductivity of LiNi 1/3 Co 1/3 Mn 1/3 O 2 material. By comparing with the pure LiNi 1/3 Co 1/3 Mn 1/3 O 2 and cathode modified by CNTs or Ag, the as-obtained LiNi 1/3 Co 1/3 Mn 1/3 O 2 –CNT/Ag electrode exhibits the best rate capability (120.6 mAh/g at 5C) and cycle performance (134.2 mAh/g at 1C with a capacity retention of 94.4% over 100 cycles). With the construction of 3D spatial conductive network, the novel hybrid CNT/Ag demonstrates itself a promising strategy to improve Li storage performance for lithium ion batteries

  19. Mechanical characterization and ion release of bioactive dental composites containing calcium phosphate particles.

    Science.gov (United States)

    Natale, Livia C; Rodrigues, Marcela C; Alania, Yvette; Chiari, Marina D S; Boaro, Leticia C C; Cotrim, Marycel; Vega, Oscar; Braga, Roberto R

    2018-08-01

    to verify the effect of the addition of dicalcium phosphate dihydrate (DCPD) particles functionalized with di- or triethylene glycol dimethacrylate (DEGDMA or TEGDMA) on the degree of conversion (DC), post-gel shrinkage (PS), mechanical properties, and ion release of experimental composites. Four composites were prepared containing a BisGMA/TEGDMA matrix and 60 vol% of fillers. The positive control contained only barium glass fillers, while in the other composites 15 vol% of the barium was replaced by DCPD. Besides the functionalized particles, non-functionalized DCPD was also tested. DC after 24 h (n = 3) was determined by FTIR spectroscopy. The strain gage method was used to obtain PS 5 min after photoactivation (n = 5). Flexural strength and modulus (n = 10) were calculated based on the biaxial flexural test results, after specimen storage for 24 h or 60 days in water. The same storage times were used for fracture toughness testing (FT, n = 10). Calcium and phosphate release up to 60 days was quantified by ICP-OES (n = 3). Data were analyzed by ANOVA/Tukey test (alpha: 5%). Composites containing functionalized DCPD presented higher DC than the control (p composites (p composite with DEGDMA-functionalized DCPD presented fracture strength similar to the control, while for flexural modulus only the composite with TEGDMA-functionalized particles was lower than the control (p composites containing DCPD was higher than the control after 60 days (p composite with non-functionalized DCPD at 15 days and no significant reductions were observed for composites with functionalized DCPD during the observation period (p composites, phosphate release was higher at 15 days than in the subsequent periods, and no difference among them was recorded at 45 and 60 days (p composite with DEGDMA-functionalized particles was the only material with strength similar to the control after 60 days in water; however, it also presented the highest

  20. Ion channel activity of membrane vesicles released from sea urchin sperm during the acrosome reaction

    International Nuclear Information System (INIS)

    Schulz, Joseph R.; Vega-Beltran, Jose L. de la; Beltran, Carmen; Vacquier, Victor D.; Darszon, Alberto

    2004-01-01

    The sperm acrosome reaction (AR) involves ion channel activation. In sea urchin sperm, the AR requires Ca 2+ and Na + influx and K + and H + efflux. During the AR, the plasma membrane fuses with the acrosomal vesicle membrane forming hybrid membrane vesicles that are released from sperm into the medium. This paper reports the isolation and preliminary characterization of these acrosome reaction vesicles (ARVs), using synaptosome-associated protein of 25 kDa (SNAP-25) as a marker. Isolated ARVs have a unique protein composition. The exocytosis regulatory proteins vesicle-associated membrane protein and SNAP-25 are inside ARVs, as judged by protease protection experiments, and membrane associated based on Triton X-114 partitioning. ARVs fused with planar bilayers display three main types of single channel activity. The most frequently recorded channel is cationic, weakly voltage dependent and has a low open probability that increases with negative potentials. This channel is activated by cAMP, blocked by Ba 2+ , and has a PK + /PNa + selectivity of 4.5. ARVs represent a novel membrane preparation suitable to deepen our understanding of ion channel activity in the AR and during fertilization

  1. Tailoring silver nanoparticle construction using dendrimer templated silica networks

    International Nuclear Information System (INIS)

    Liu Xiaojun; Kakkar, Ashok

    2008-01-01

    We have examined the role of the internal environment of dendrimer templated silica networks in tailoring the construction of silver nanoparticle assemblies. Silica networks from which 3,5-dihydroxybenzyl alcohol based dendrimer templates have been completely removed, slowly wet with an aqueous solution of silver acetate. The latter then reacts with internal silica silanol groups, leading to chemisorption of silver ions, followed by the growth of silver oxide nanoparticles. Silica network constructed using generation 4 dendrimer contains residual dendrimer template, and mixes with aqueous silver acetate solution easily. Upon chemisorption, silver ions get photolytically reduced to silver metal under a stabilizing dendrimer environment, leading to the formation of silver metal nanoparticles

  2. Probabilistic approach for assessing infants' health risks due to ingestion of nanoscale silver released from consumer products.

    Science.gov (United States)

    Pang, Chengfang; Hristozov, Danail; Zabeo, Alex; Pizzol, Lisa; Tsang, Michael P; Sayre, Phil; Marcomini, Antonio

    2017-02-01

    Silver nanoparticles (n-Ag) are widely used in consumer products and many medical applications because of their unique antibacterial properties. Their use is raising concern about potential human exposures and health effects. Therefore, it is informative to assess the potential human health risks of n-Ag in order to ensure that nanotechnology-based consumer products are deployed in a safe and sustainable way. Even though toxicity studies clearly show the potential hazard of n-Ag, there have been few attempts to integrate hazard and exposure assessments to evaluate risks. The underlying reason for this is the difficulty in characterizing exposure and the lack of toxicity studies essential for human health risk assessment (HHRA). Such data gaps introduce significant uncertainty into the risk assessment process. This study uses probabilistic methods to assess the relative uncertainty and potential risks of n-Ag exposure to infants. In this paper, we estimate the risks for infants potentially exposed to n-Ag through drinking juice or milk from sippy cups or licking baby blankets containing n-Ag. We explicitly evaluate uncertainty and variability contained in available dose-response and exposure data in order to make the risk characterization process transparent. Our results showed that individual margin of exposures for oral exposure to sippy cups and baby blankets containing n-Ag exhibited minimal risk. Copyright © 2016. Published by Elsevier Ltd.

  3. Availability of mollusks as ''biological monitor'' to monitoring of the long-lived silver isotope released into the marine environment

    International Nuclear Information System (INIS)

    Watabe, Teruhisa; Yokosuka, Setsuko; Kurosawa, Akiko

    2003-01-01

    The species of mollusks often show unique physiological properties and the elemental composition different from those of fishes as observed in the blood constituents. Much higher concentrations of metal elements such as cupper, zinc, cadmium and so on have been reported for squids and bivalves than other organisms. The present study reports the results of gamma spectrometry analyses for two species of gastropods (Buccinum isaotakii and Buccinum striatissimum), one of the important species of mollusks, inhabiting on the sea bottom at the depth of some hundreds meters off the coast and for squids (Todarodes pacificus, Thysanoteuthis rhombus, etc.) landed at several fishing ports in Japan. It would be noted that 108m Ag (half-life time: 418.21y) was commonly detected in the viscera of both gastropods and squids usually at the radioactivity level higher than 137 Cs. A discussion on the distribution and inventory of 108m Ag in the water column was attempted on the basis of the data on its specific activity, which was derived from the data on stable silver for the samples of interest obtained by analyses using ICP-AES. Special attention was directed to the efficacy and applicability of the mollusks having an affinity for this element to the environmental monitoring as indices. (author)

  4. Effect of silver nanoparticles on human mesenchymal stem cell differentiation

    Directory of Open Access Journals (Sweden)

    Christina Sengstock

    2014-11-01

    Full Text Available Background: Silver nanoparticles (Ag-NP are one of the fastest growing products in nano-medicine due to their enhanced antibacterial activity at the nanoscale level. In biomedicine, hundreds of products have been coated with Ag-NP. For example, various medical devices include silver, such as surgical instruments, bone implants and wound dressings. After the degradation of these materials, or depending on the coating technique, silver in nanoparticle or ion form can be released and may come into close contact with tissues and cells. Despite incorporation of Ag-NP as an antibacterial agent in different products, the toxicological and biological effects of silver in the human body after long-term and low-concentration exposure are not well understood. In the current study, we investigated the effects of both ionic and nanoparticulate silver on the differentiation of human mesenchymal stem cells (hMSCs into adipogenic, osteogenic and chondrogenic lineages and on the secretion of the respective differentiation markers adiponectin, osteocalcin and aggrecan.Results: As shown through laser scanning microscopy, Ag-NP with a size of 80 nm (hydrodynamic diameter were taken up into hMSCs as nanoparticulate material. After 24 h of incubation, these Ag-NP were mainly found in the endo-lysosomal cell compartment as agglomerated material. Cytotoxicity was observed for differentiated or undifferentiated hMSCs treated with high silver concentrations (≥20 µg·mL−1 Ag-NP; ≥1.5 µg·mL−1 Ag+ ions but not with low-concentration treatments (≤10 µg·mL−1 Ag-NP; ≤1.0 µg·mL−1 Ag+ ions. Subtoxic concentrations of Ag-NP and Ag+ ions impaired the adipogenic and osteogenic differentiation of hMSCs in a concentration-dependent manner, whereas chondrogenic differentiation was unaffected after 21 d of incubation. In contrast to aggrecan, the inhibitory effect of adipogenic and osteogenic differentiation was confirmed by a decrease in the secretion of

  5. Speciation Matters: Bioavailability of Silver and Silver Sulfide Nanoparticles to Alfalfa (Medicago sativa).

    Science.gov (United States)

    Stegemeier, John P; Schwab, Fabienne; Colman, Benjamin P; Webb, Samuel M; Newville, Matthew; Lanzirotti, Antonio; Winkler, Christopher; Wiesner, Mark R; Lowry, Gregory V

    2015-07-21

    Terrestrial crops are directly exposed to silver nanoparticles (Ag-NPs) and their environmentally transformed analog silver sulfide nanoparticles (Ag2S-NPs) when wastewater treatment biosolids are applied as fertilizer to agricultural soils. This leads to a need to understand their bioavailability to plants. In the present study, the mechanisms of uptake and distribution of silver in alfalfa (Medicago sativa) were quantified and visualized upon hydroponic exposure to Ag-NPs, Ag2S-NPs, and AgNO3 at 3 mg total Ag/L. Total silver uptake was measured in dried roots and shoots, and the spatial distribution of elements was investigated using transmission electron microscopy (TEM) and synchrotron-based X-ray imaging techniques. Despite large differences in release of Ag(+) ions from the particles, Ag-NPs, Ag2S-NPs, and Ag(+) became associated with plant roots to a similar degree, and exhibited similarly limited (<1%) amounts of translocation of silver into the shoot system. X-ray fluorescence (XRF) mapping revealed differences in the distribution of Ag into roots for each treatment. Silver nanoparticles mainly accumulated in the (columella) border cells and elongation zone, whereas Ag(+) accumulated more uniformly throughout the root. In contrast, Ag2S-NPs remained largely adhered to the root exterior, and the presence of cytoplasmic nano-SixOy aggregates was observed. Exclusively in roots exposed to particulate silver, NPs smaller than the originally dosed NPs were identified by TEM in the cell walls. The apparent accumulation of Ag in the root apoplast determined by XRF, and the presence of small NPs in root cell walls suggests uptake of partially dissolved NPs and translocation along the apoplast.

  6. On the Ni-Ion release rate from surfaces of binary NiTi shape memory alloys

    Science.gov (United States)

    Ševčíková, Jana; Bártková, Denisa; Goldbergová, Monika; Kuběnová, Monika; Čermák, Jiří; Frenzel, Jan; Weiser, Adam; Dlouhý, Antonín

    2018-01-01

    The study is focused on Ni-ion release rates from NiTi surfaces exposed in the cell culture media and human vascular endothelial cell (HUVEC) culture environments. The NiTi surface layers situated in the depth of 70 μm below a NiTi oxide scale are affected by interactions between the NiTi alloys and the bio-environments. The finding was proved with use of inductively coupled plasma mass spectrometry and electron microscopy experiments. As the exclusive factor controlling the Ni-ion release rates was not only thicknesses of the oxide scale, but also the passivation depth, which was two-fold larger. Our experimental data strongly suggested that some other factors, in addition to the Ni concentration in the oxide scale, admittedly hydrogen soaking deep below the oxide scale, must be taken into account in order to rationalize the concentrations of Ni-ions released into the bio-environments. The suggested role of hydrogen as the surface passivation agent is also in line with the fact that the Ni-ion release rates considerably decrease in NiTi samples that were annealed in controlled hydrogen atmospheres prior to bio-environmental exposures.

  7. Preparation and characterization of silver loaded montmorillonite modified with sulfur amino acid

    Energy Technology Data Exchange (ETDEWEB)

    Li, Tian, E-mail: phdlitian@163.com; Lin, Oulian; Lu, Zhiyuan; He, Liuimei; Wang, Xiaosheng

    2014-06-01

    The Na{sup +} montmorillonite (MMT) was modified with sulfur containing amino acid (L-cystine, L-cysteine or L-methionine) and characterized by energy dispersive spectrometer (EDS), X-ray diffraction (XRD) and Fourier transform infrared spectrum (FT-IR). The results showed the modification was smooth and the surface condition of MMT was changed with sulfur containing groups. Then silver was loaded on the modified MMTs via ion-exchange reaction under microwave irradiation, the spectra of X-ray photoelectron spectroscopy (XPS), EDS and FT-IR confirmed the successful loading of massive silver and the strong interaction between sulfur and silver, the silver loaded L-cystine modified MMT (Ag@AA-MMT-3) with a silver content of 10.93 wt% was the highest of all. Further more, the Ag@AA-MMT-3 was under the irradiation of a UV lamp to turn silver ions to silver nano particles (Ag NPs). The XPS, specific surface area (SSA), transmission electron microscopy (TEM), XRD patterns and UV–vis spectra proved the existence of uniform nano scaled metallic Ag NPs. By contrast, the UV irradiated Ag@AA-MMT-3 (Ag@AA-MMT-UV) showed a much better slow release property than Ag@AA-MMT-3 or Ag@MMT. The Ag@AA-MMT-UV showing a large inhibition zone and high inhibition ratio presented very good antibacterial property.

  8. Gene Expression, Protein Function and Pathways of Arabidopsis thaliana Responding to Silver Nanoparticles in Comparison to Silver Ions, Cold, Salt, Drought, and Heat

    Directory of Open Access Journals (Sweden)

    Eisa Kohan-Baghkheirati

    2015-03-01

    Full Text Available Silver nanoparticles (AgNPs have been widely used in industry due to their unique physical and chemical properties. However, AgNPs have caused environmental concerns. To understand the risks of AgNPs, Arabidopsis microarray data for AgNP, Ag+, cold, salt, heat and drought stresses were analyzed. Up- and down-regulated genes of more than two-fold expression change were compared, while the encoded proteins of shared and unique genes between stresses were subjected to differential enrichment analyses. AgNPs affected the fewest genes (575 in the Arabidopsis genome, followed by Ag+ (1010, heat (1374, drought (1435, salt (4133 and cold (6536. More genes were up-regulated than down-regulated in AgNPs and Ag+ (438 and 780, respectively while cold down-regulated the most genes (4022. Responses to AgNPs were more similar to those of Ag+ (464 shared genes, cold (202, and salt (163 than to drought (50 or heat (30; the genes in the first four stresses were enriched with 32 PFAM domains and 44 InterPro protein classes. Moreover, 111 genes were unique in AgNPs and they were enriched in three biological functions: response to fungal infection, anion transport, and cell wall/plasma membrane related. Despite shared similarity to Ag+, cold and salt stresses, AgNPs are a new stressor to Arabidopsis.

  9. Ammonium ion interaction with conditioned natural zeolite with silver and its effect on the disinfection of polluted water in front of a consortium of gram (+) and gram (-) microorganisms; Interaccion del ion amonio con zeolita natural acondicionada con plata y su efecto sobre la desinfeccion de agua contaminada frente a un consorcio de microorganismos gram (+) y gram (-)

    Energy Technology Data Exchange (ETDEWEB)

    Gonzaga G, V. E.

    2013-07-01

    Clinoptilolite zeolite material is a relative abundance in Mexico, which has ion exchange properties, therefore, has the ability to retain metal ions giving it an application in the process of disinfecting of water contaminated with pathogenic microorganisms. In this research, we conducted a study of disinfection of water contaminated with a microbial consortium, from a zeolite rock clinoptilolite from a deposit located in the State of Guerrero. Initially, the zeolite prepared by the grinding and sieving, for conditioning with NaCl and subsequently with AgNO{sub 3}, finally to be characterized using the techniques of scanning electron microscopy and X-ray diffraction. Tests using columns packed with zeolite material, the effect of zeolite bactericidal conditioned with silver (ZGAg) against a microbial consortium consisting of Escherichia coli and Sthapyloccocus aureus in aqueous solution in the presence of ammonium ions used to increase the ion exchange with zeolite fitted with silver. To describe curves disinfecting a continuous flow system is adapted Gu pta model, which describes the kinetics and equilibrium adsorption process, considering the microorganisms as the adsorbate and the sanitizing agent (conditioned with silver zeolite) as the adsorbent. Characterization results show that in the scanning electron microscopy (Sem), no changes were obtained on the morphology of typical clinoptilolite crystals before and after that was modified with sodium and then with silver, it is worth mentioning however that fitted with silver zeolite (ZGAg), small particles are seen on the zeolite material which when analyzed by energy dispersive spectroscopy (EDS), we found a high concentration of Ag +. The disinfection period is increased as the concentration increased ammonium ions, this behavior is attributed to the ion exchange that occurs between the ammonium ions and silver ions. A lower percentage of inactivation is due, therefore, to a lesser amount of money available to

  10. Diclofenac sodium ion exchange resin complex loaded melt cast films for sustained release ocular delivery.

    Science.gov (United States)

    Adelli, Goutham R; Balguri, Sai Prachetan; Bhagav, Prakash; Raman, Vijayasankar; Majumdar, Soumyajit

    2017-11-01

    The goal of the present study is to develop polymeric matrix films loaded with a combination of free diclofenac sodium (DFS free ) and DFS:Ion exchange resin complexes (DFS:IR) for immediate and sustained release profiles, respectively. Effect of ratio of DFS and IR on the DFS:IR complexation efficiency was studied using batch processing. DFS:IR complex, DFS free , or a combination of DFS free  +   DFS:IR loaded matrix films were prepared by melt-cast technology. DFS content was 20% w/w in these matrix films. In vitro transcorneal permeability from the film formulations were compared against DFS solution, using a side-by-side diffusion apparatus, over a 6 h period. Ocular disposition of DFS from the solution, films and corresponding suspensions were evaluated in conscious New Zealand albino rabbits, 4 h and 8 h post-topical administration. All in vivo studies were carried out as per the University of Mississippi IACUC approved protocol. Complexation efficiency of DFS:IR was found to be 99% with a 1:1 ratio of DFS:IR. DFS release from DFS:IR suspension and the film were best-fit to a Higuchi model. In vitro transcorneal flux with the DFS free  +   DFS:IR (1:1) (1 + 1) was twice that of only DFS:IR (1:1) film. In vivo, DFS solution and DFS:IR (1:1) suspension formulations were not able to maintain therapeutic DFS levels in the aqueous humor (AH). Both DFS free and DFS free  +   DFS:IR (1:1) (3 + 1) loaded matrix films were able to achieve and maintain high DFS concentrations in the AH, but elimination of DFS from the ocular tissues was much faster with the DFS free formulation. DFS free  +   DFS:IR combination loaded matrix films were able to deliver and maintain therapeutic DFS concentrations in the anterior ocular chamber for up to 8 h. Thus, free drug/IR complex loaded matrix films could be a potential topical ocular delivery platform for achieving immediate and sustained release characteristics.

  11. Poly(acrylic acid)-templated silver nanoclusters as a platform for dual fluorometric turn-on and colorimetric detection of mercury (II) ions.

    Science.gov (United States)

    Tao, Yu; Lin, Youhui; Huang, Zhenzhen; Ren, Jinsong; Qu, Xiaogang

    2012-01-15

    An easy prepared fluorescence turn-on and colorimetric dual channel probe was developed for rapid assay of Hg(2+) ions with high sensitivity and selectivity by using poly(acrylic acid)-templated silver nanoclusters (PAA-AgNCs). The PAA-AgNCs exhibited weak fluorescence, while upon the addition of Hg(2+) ions, AgNCs gives a dramatic increase in fluorescence as a result of the changes of the AgNCs states. The detection limit was estimated to be 2 nM, which is much lower than the Hg(2+) detection requirement for drinking water of U.S. Environmental Protection Agency, and the turn-on sensing mode offers additional advantage to efficiently reduce background noise. Also, a colorimetric assay of Hg(2+) ions can be realized due to the observed absorbance changes of the AgNCs. More importantly, the method was successfully applied to the determination of Hg(2+) ions in real water samples, which suggests our proposed method has a great potential of application in environmental monitoring. Copyright © 2011 Elsevier B.V. All rights reserved.

  12. Antimicrobial properties of zeolite-X and zeolite-A ion-exchanged with silver, copper, and zinc against a broad range of microorganisms.

    Science.gov (United States)

    Demirci, Selami; Ustaoğlu, Zeynep; Yılmazer, Gonca Altın; Sahin, Fikrettin; Baç, Nurcan

    2014-02-01

    Zeolites are nanoporous alumina silicates composed of silicon, aluminum, and oxygen in a framework with cations, water within pores. Their cation contents can be exchanged with monovalent or divalent ions. In the present study, the antimicrobial (antibacterial, anticandidal, and antifungal) properties of zeolite type X and A, with different Al/Si ratio, ion exchanged with Ag(+), Zn(2+), and Cu(2+) ions were investigated individually. The study presents the synthesis and manufacture of four different zeolite types characterized by scanning electron microscopy and X-ray diffraction. The ion loading capacity of the zeolites was examined and compared with the antimicrobial characteristics against a broad range of microorganisms including bacteria, yeast, and mold. It was observed that Ag(+) ion-loaded zeolites exhibited more antibacterial activity with respect to other metal ion-embedded zeolite samples. The results clearly support that various synthetic zeolites can be ion exchanged with Ag(+), Zn(2+), and Cu(2+) ions to acquire antimicrobial properties or ion-releasing characteristics to provide prolonged or stronger activity. The current study suggested that zeolite formulations could be combined with various materials used in manufacturing medical devices, surfaces, textiles, or household items where antimicrobial properties are required.

  13. [The effect of hydrogen peroxide on the electrochemical corrosion properties and metal ions release of nickel-chromium dental alloys].

    Science.gov (United States)

    Wang, Jue; Qiao, Guang-yan

    2013-04-01

    To investigate the effect of hydrogen peroxide on the electrochemical corrosion and metal ions release of nickel-chromium dental alloys. The corrosion resistance of nickel-chromium dental alloys was compared by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curve (PD) methods in artificial saliva after immersed in different concentrations of hydrogen peroxide for 112 h. The metal ions released from nickel-chromium dental alloys to the artificial saliva were detected after electrochemical measurements using inductively coupled plasma mass spectrometry (ICP-MS). The data was statistically analyzed by analysis of variance (ANOVA) using SPSS 13.0 software package. The electrochemical experiment showed that the sequence of polarization resistance in equivalent circuit (Rct), corrosion potential (Ecorr), pitting breakdown potential (Eb), and the difference between Ecorr and Eb representing the "pseudo-passivation" (δE) of nickel-chromium alloys in artificial saliva was 30% alloys to the artificial saliva, and the order of the concentrations of metal ions was 0% corrosion resistance of nickel-chromium dental alloys decrease after immersed in different concentrations of hydrogen peroxide for 112 h. Nickel-chromium dental alloys are more prone to corrosion in the artificial saliva with the concentration of hydrogen peroxide increased, and more metal ions are released in the artificial saliva.

  14. Antibacterial effect of silver nanofilm modified stainless steel surface

    Science.gov (United States)

    Fang, F.; Kennedy, J.; Dhillon, M.; Flint, S.

    2015-03-01

    Bacteria can attach to stainless steel surfaces, resulting in the colonization of the surface known as biofilms. The release of bacteria from biofilms can cause contamination of food such as dairy products in manufacturing plants. This study aimed to modify stainless steel surfaces with silver nanofilms and to examine the antibacterial effectiveness of the modified surface. Ion implantation was applied to produce silver nanofilms on stainless steel surfaces. 35 keV Ag ions were implanted with various fluences of 1 × 1015 to 1 × 1017 ions•cm-2 at room temperature. Representative atomic force microscopy characterizations of the modified stainless steel are presented. Rutherford backscattering spectrometry spectra revealed the implanted atoms were located in the near-surface region. Both unmodified and modified stainless steel coupons were then exposed to two types of bacteria, Pseudomonas fluorescens and Streptococcus thermophilus, to determine the effect of the surface modification on bacterial attachment and biofilm development. The silver modified coupon surface fluoresced red over most of the surface area implying that most bacteria on coupon surface were dead. This study indicates that the silver nanofilm fabricated by the ion implantation method is a promising way of reducing the attachment of bacteria and delay biofilm formation.

  15. Characterization of fatty acid and triacylglycerol composition in animal fats using silver-ion and non-aqueous reversed-phase high-performance liquid chromatography/mass spectrometry and gas chromatography/flame ionization detection

    Czech Academy of Sciences Publication Activity Database

    Lísa, M.; Netušilová, K.; Franěk, L.; Dvořáková, H.; Vrkoslav, Vladimír; Holčapek, M.

    2011-01-01

    Roč. 1218, č. 42 (2011), s. 7499-7510 ISSN 0021-9673 R&D Projects: GA ČR GA203/09/0139 Institutional research plan: CEZ:AV0Z40550506 Keywords : silver-ion HPLC * non-aqueous reversed-phase HPLC * triacylglycerol Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 4.531, year: 2011

  16. Biological synthesis of silver nanoparticles

    International Nuclear Information System (INIS)

    Maliszewska, I; Szewczyk, K; Waszak, K

    2009-01-01

    Fungus-mediated synthesis of silver nanoparticles is reported. The nanosilver was formed in contact with the cell-free filtrate of Penicillium strain studied. The nanoparticles were characterized by means of the UV-Vis spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The synthesized nanosilver showed a absorbed maximum at 425 nm in the visible region. The SEM characterization of the fungus cells treated with silver nitrite indicated that the protein might be responsible for the reduction of silver ions. Transmission electron microscopy (TEM) micrograph showed formation of silver nanoparticles in the range of 10-100 nm.

  17. Mechanical properties and ion release from bioactive restorative composites containing glass fillers and calcium phosphate nano-structured particles.

    Science.gov (United States)

    Chiari, Marina D S; Rodrigues, Marcela C; Xavier, Tathy A; de Souza, Eugen M N; Arana-Chavez, Victor E; Braga, Roberto R

    2015-06-01

    To evaluate the effect of the replacement of barium glass by dicalcium phosphate dihydrate (DCPD) particles on the mechanical properties and degree of conversion (DC) of composites. Additionally, calcium and hydrogen phosphate (HPO4(2-)) release were followed for 28 days. Nine composites containing equal parts (in mols) of BisGMA and TEGDMA and 40, 50 or 60 vol% of total filler were manipulated. Filler phase was constituted by silanated barium glass and 0%, 10% or 20% of DCPD particles. DC was determined by near-FTIR. Biaxial flexural strength (BFS) and modulus (E) were tested using the "piston on three balls" method, while fracture toughness (KIc) used the "single edge notched beam" method. Specimens were tested after 24h and 28 days in water. Ion release was determined using inductively coupled plasma optical emission spectrometry (ICP-OES). Data were analyzed by ANOVA/Tukey (DC and ion release) or Kruskal-Wallis/Mann-Whitney (mechanical properties; alpha: 5%). DC was not affected by DCPD. The presence of DCPD reduced BFS for both storage times, while differences in E became evident after 28 days. After 24h, KIc increased with the addition of DCPD; after 28 days, however, KIc decreased only for DCPD-containing composites. Calcium release was similar for both DCPD contents and remained fairly constant during the 28-day period. Overall, HPO4(2-) release was higher at 7 days and did not decrease after 14 days. The composite with the highest filler level and 10% DCPD represented the best compromise between mechanical properties after aging in water and ion release. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  18. Solvothermal syntheses and characterization of three new silver(I)/copper(I)-thioarsenates based on As{sup 2+}/As{sup 3+} ions

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Hua-Gang, E-mail: hgyao@gdpu.edu.cn [School of Chemistry and Chemical Engineering, Guangdong Pharmaceutical University, Zhongshan 528458 (China); Guangdong Cosmetics Engineering & Technology Research Center, Zhongshan 528458 (China); Tang, Cheng-Fei [School of Chemistry and Chemical Engineering, Guangdong Pharmaceutical University, Zhongshan 528458 (China); An, Yong-Lin [Department of Chemistry, Dalian University of Technology, Dalian 116024 (China); Ou, Zi-Jian; Wu, Guo-Hao; Lan, Pei; Zheng, Yi-Long [School of Chemistry and Chemical Engineering, Guangdong Pharmaceutical University, Zhongshan 528458 (China)

    2017-02-15

    Three new silver(I)/copper(I)-thioarsenates KAgAs{sup II}S{sub 2} (1), RbCu{sub 2}As{sup III}S{sub 3} (2) and RbCu{sub 4}As{sup III}S{sub 4} (3) have been solvothermally synthesized and structurally characterized. 1 exhibits a two-dimensional anionic network built up by As−As bond connecting the left- and right-handed helical [AgS{sub 2}]{sup 4−} chains, and represents the first examples of thioarsenates(II). The structure of 2 consists of two kinds of helical [Cu{sub 2}S{sub 3}]{sup 4–} chains linked by the arsenic atoms to form double layers with rubidium ions between the layers. Compound 3 is built up of infinite [Cu{sub 2}S{sub 2}]{sup 2–} chain and layered [Cu{sub 6}As{sub 2}S{sub 6}] linked to form a three-dimensional anionic framework, [Cu{sub 4}AsS{sub 4}]{sup –}, and containing channels in which the rubidium cations reside. The optical properties of 1–3 have been investigated by UV–vis spectroscopy. - Graphical abstract: Three new silver(I)/copper(I)-thioarsenates have been solvothermally synthesized and structurally characterized. 1 represents the first examples of thioarsenates(II) while compounds 2 and 3 possess noncondensed pyramidal AsS{sub 3}{sup 3–} unit.

  19. Application of Silver Ion High-Performance Liquid Chromatography for Quantitative Analysis of Selected n-3 and n-6 PUFA in Oil Supplements.

    Science.gov (United States)

    Czajkowska-Mysłek, Anna; Siekierko, Urszula; Gajewska, Magdalena

    2016-04-01

    The aim of this study was to develop a simple method for simultaneous determination of selected cis/cis PUFA-LNA (18:2), ALA (18:3), GLA (18:3), EPA (20:5), and DHA (22:6) by silver ion high-performance liquid chromatography coupled to a diode array detector (Ag-HPLC-DAD). The separation was performed on three Luna SCX Silver Loaded columns connected in series maintained at 10 °C with isocratic elution by 1% acetonitrile in n-hexane. The applied chromatographic system allowed a baseline separation of standard mixture of n-3 and n-6 fatty acid methyl esters containing LNA, DHA, and EPA and partial separation of ALA and GLA positional isomers. The method was validated by means of linearity, precision, stability, and recovery. Limits of detection (LOD) for considered PUFA standard solutions ranged from 0.27 to 0.43 mg L(-1). The developed method was used to evaluate of n-3 and n-6 fatty acids contents in plant and fish softgel oil capsules, results were compared with reference GC-FID based method.

  20. Silver percutaneous absorption after exposure to silver nanoparticles: a comparison study of three human skin graft samples used for clinical applications.

    Science.gov (United States)

    Bianco, C; Adami, G; Crosera, M; Larese, F; Casarin, S; Castagnoli, C; Stella, M; Maina, G

    2014-11-01

    Silver nanoparticles (AgNPs) are increasingly applied to a wide range of materials for biomedical use. These enable a close contact with human skin, thanks to the large release of silver ions that is responsible for a broad spectrum of antimicrobial activity. Silver can permeate the skin; however, there are no data available on silver permeation through skin grafts commonly used in burns recovery. The aim of our study was to evaluate silver penetration using fresh, cryopreserved, and glycerolized human skin grafts after exposure to a suspension of AgNPs in synthetic sweat using a Franz diffusion cell apparatus for 24 h. Silver permeation profiles revealed a significantly higher permeation through glycerolized skin compared with both fresh and cryopreserved skin: 24-h silver flux penetration was 0.2 ng cm(-2) h(-1) (lag time: 8.2 h) for fresh skin, 0.3 ng cm(-2) h(-1) (lag time: 10.9 h) for cryopreserved skin, and 3.8 ng cm(-2) h(-1) (lag time: 6.3 h) for glycerolized skin. Permeation through glycerolized skin is significantly higher compared to both fresh and cryopreserved skin. This result can generate relevant clinical implications for burns treatment with products containing AgNPs. Copyright © 2014 Elsevier Ltd and ISBI. All rights reserved.

  1. H-isotope retention and thermal/ion-induced release in boronized films

    International Nuclear Information System (INIS)

    Walsh, D.S.; Doyle, B.L.; Wampler, W.R.; Hays, A.K.

    1990-01-01

    Over the past decade, it has been clearly demonstrated that the composition of the very near surface (∼100nm) of plasma-interactive components plays a determinant role in most processes which occur in the plasma-edge of Tokamaks. Two very successful techniques to effect control of the plasma-wall interaction are (1) in-situ deposition of amorphous carbon or boron-carbon films and (2) the use of He/C conditioning discharges or He glow discharge cleaning to modify the near surface of bulk graphite components. We have deposited boronized layers into Si using plasma-assisted CVD and sputter deposition. The PCVD deposition conditions were as close as possible to those used in TFTR, and some films deposited in TFTR have also been studied. Using these two deposition techniques, B x CH y films have been produced with x varying from 1/2 -- 4, and y from ∼1 (sputtered) to ∼3 (PCVD). Most films also contained significant amounts of 0. Thermal and ion-induced release of H-isotopes from BC films is qualitatively similar to that measured for graphite. Implanted H saturates in these films at a H/host atom ratio of 0.7 which is considerably higher than that of graphite(∼0.4). As-deposited PCVD films are already saturated with H, while sputtered films are not. Sputtered BC films therefore possess an inherent H-pumping capability which could prove to be extremely beneficial to TFTR. 16 refs., 5 figs., 1 tab

  2. Metal is not inert: role of metal ions released by biocorrosion in aseptic loosening--current concepts.

    Science.gov (United States)

    Cadosch, Dieter; Chan, Erwin; Gautschi, Oliver P; Filgueira, Luis

    2009-12-15

    Metal implants are essential therapeutic tools for the treatment of bone fractures and joint replacements. The metals and metal alloys used in contemporary orthopedic and trauma surgery are well tolerated by the majority of patients. However, complications resulting from inflammatory and immune reactions to metal implants have been well documented. This review briefly discusses the different mechanisms of metal implant corrosion in the human body, which lead to the release of significant levels of metal ions into the peri-implant tissues and the systemic blood circulation. Additionally, this article reviews the effects of the released ions on bone metabolism and the immune system and discusses their involvement in the pathophysiological mechanisms of aseptic loosening and metal hypersensitivity in patients with metal implants.

  3. Technical feasibility of using silver and copper ions electro generated in the microbiological control of cooling systems; Factibilidad tecnica para emplear iones plata y cobre electrogenerados en el control microbiologico de los sistemas de enfriamiento

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Susana M; Martinez Meza, Esteban; Alvarez Gallegos, Alberto [Instituto de Investigaciones Electricas, Temixco, Morelos (Mexico)

    2001-07-01

    The objective of this work is to determine the technical feasibility of replacing the chlorine use by another biocida (ionization of silver or copper) non dangerous in cooling waters. This technique of ionization could be used to treat the water of industrial processes in general. The used water came from the make up water of the cooling system of the Thermoelectric Power Station of Valle de Mexico (CTEVM) and residual water of the treatment plants of the Instituto Mexicano de Tecnologia del Agua (IMTA) (Mexican Institute of WaterTechnology) and the Instituto de Investigaciones Electricas (IIE). The three types of water used have similar physical, chemical and biological characteristics. The used methodology was the jar tests and by continuous system. The bacteriological analysis is indicated reaching the conclusion. The metallic systems studied in the establishment of the microbiological control in the residual water and make up water are silver, silver/copper and copper in the concentration intervals of 200 mg/l to 3000 mg/l of silver and 200 mg/l to 1200 mg/l of copper. The experiments performed in the jar tests (closed system) were carried out at two temperatures (25 {+-} 0.5 and 32 {+-} 0.5 ) without pH control; whereas in the continuous system the pH was maintained in the pH interval of 7 to 8 by means of the sulfuric acid addition and a delta temperature of 10 was maintained (27 {+-} 5 ). The pH, the conductivity and the temperature were continuously measured. Graphs are shown on the effect silver/copper ions on the annihilation of total coliform bacteria and fecal coliforms the effect of the concentration of the silver metallic ion is given as a figure on the annihilation of bacteria related to iron. It is possible to conclude that the plant systems studied of silver/copper and copper turned out to be a good alternative with a minimum environmental impact to replace chlorine in the cooling systems. These systems managed microbiologically to lower the

  4. Facile fabrication of dual emissive nanospheres via the self-assembling of CdSe@CdS and zinc phthalocyanine and their application for silver ion detection

    Science.gov (United States)

    Liu, Shuning; Liu, Chenchen; Luan, Xinying; Yao, Rui; Feng, Yakai

    2017-09-01

    The far-red/near infrared photoluminescence of zinc phthalocyanines would be strongly quenched once they are aggregated, which will obviously hinder their wide applications in environmental, energy related and biomedical fields. Herein, the ultra-small sized semiconductor quantum dots with core-shell structures (CdSe@CdS) have been firstly synthesized and then assembled with a dendritic zinc phthalocyanine (ZnPc) in the H2O/DMF mixed solvent to obtain monodispersed nanospheres. Finally, it was found that the resultant ethanolic colloids can be employed as a sensitive and specific fluorescent nanoprobe for silver ions discrimination with a limit of detection (LOD) approaching to 10-8 mol/L.

  5. Galvanic Corrosion of and Ion Release from Various Orthodontic Brackets and Wires in a Fluoride-containing Mouthwash

    Directory of Open Access Journals (Sweden)

    Soodeh Tahmasbi

    2015-09-01

    Full Text Available Background and aims. This study compared the galvanic corrosion of orthodontic wires and brackets from various man-ufacturers following exposure to a fluoride mouthwash. Materials and methods. This study was conducted on 24 lower central incisor 0.022” Roth brackets of four different commercially available brands (Dentaurum, American Orthodontics, ORJ, Shinye. These brackets along with stainless steel (SS or nickel-titanium (NiTi orthodontic wires (0.016", round were immersed in Oral-B mouthwash containing 0.05% sodium fluoride for 28 days. The electric potential (EP difference of each bracket-wire couple was measured with a Satu-rated Calomel Reference Electrode (Ag/AgCl saturated with KCl via a voltmeter. The ions released in the electrolyte weremeasured with an atomic absorption spectrometer. All the specimens were assessed under a stereomicroscope and speci-mens with corrosion were analyzed with scanning electron microscopy (SEM. Data were analyzed using ANOVA. Results. The copper ions released from specimens with NiTi wire were greater than those of samples containing SS wire. ORJ brackets released more Cu ions than other samples. The Ni ions released from Shinye brackets were significantly more than those of other specimens (P < 0.05. Corrosion rate of brackets coupled with NiTi wires was higher than that of brack-ets coupled with SS wires. Light and electron microscopic observations showed greater corrosion of ORJ brackets. Conclusion. In fluoride mouthwash, Shinye and ORJ brackets exhibited greater corrosion than Dentaurum and American Orthodontics brackets. Stainless steel brackets used with NiTi wires showed greater corrosion and thus caution is recom-mended when using them.

  6. Galvanic Corrosion of and Ion Release from Various Orthodontic Brackets and Wires in a Fluoride-containing Mouthwash.

    Science.gov (United States)

    Tahmasbi, Soodeh; Ghorbani, Mohammad; Masudrad, Mahdis

    2015-01-01

    Background and aims. This study compared the galvanic corrosion of orthodontic wires and brackets from various manufacturers following exposure to a fluoride mouthwash. Materials and methods. This study was conducted on 24 lower central incisor 0.022" Roth brackets of four different commercially available brands (Dentaurum, American Orthodontics, ORJ, Shinye). These brackets along with stainless steel (SS) or nickel-titanium (NiTi) orthodontic wires (0.016", round) were immersed in Oral-B mouthwash containing 0.05% sodium fluoride for 28 days. The electric potential (EP) difference of each bracket-wire couple was measured with a Saturated Calomel Reference Electrode (Ag/AgCl saturated with KCl) via a voltmeter. The ions released in the electrolyte weremeasured with an atomic absorption spectrometer. All the specimens were assessed under a stereomicroscope and specimens with corrosion were analyzed with scanning electron microscopy (SEM). Data were analyzed using ANOVA. Results. The copper ions released from specimens with NiTi wire were greater than those of samples containing SS wire. ORJ brackets released more Cu ions than other samples. The Ni ions released from Shinye brackets were significantly more than those of other specimens (P brackets coupled with NiTi wires was higher than that of brackets coupled with SS wires. Light and electron microscopic observations showed greater corrosion of ORJ brackets. Conclusion. In fluoride mouthwash, Shinye and ORJ brackets exhibited greater corrosion than Dentaurum and American Orthodontics brackets. Stainless steel brackets used with NiTi wires showed greater corrosion and thus caution is recommended when using them.

  7. Corrosion processes of triangular silver nanoparticles compared to bulk silver

    Energy Technology Data Exchange (ETDEWEB)

    Keast, V. J., E-mail: vicki.keast@newcastle.edu.au; Myles, T. A. [University of Newcastle, School of Mathematical and Physical Sciences (Australia); Shahcheraghi, N.; Cortie, M. B. [University of Technology Sydney, Institute for Nanoscale Technology (Australia)

    2016-02-15

    Excessive corrosion of silver nanoparticles is a significant impediment to their use in a variety of potential applications in the biosensing, plasmonic and antimicrobial fields. Here we examine the environmental degradation of triangular silver nanoparticles (AgNP) in laboratory air. In the early stages of corrosion, transmission electron microscopy shows that dissolution of the single-crystal, triangular, AgNP (side lengths 50–120 nm) is observed with the accompanying formation of smaller, polycrystalline Ag particles nearby. The new particles are then observed to corrode to Ag{sub 2}S and after 21 days nearly full corrosion has occurred, but some with minor Ag inclusions remaining. In contrast, a bulk Ag sheet, studied in cross section, showed an adherent corrosion layer of only around 20–50 nm in thickness after over a decade of being exposed to ambient air. The results have implications for antibacterial properties and ecotoxicology of AgNP during corrosion as the dissolution and reformation of Ag particles during corrosion will likely be accompanied by the release of Ag{sup +} ions.

  8. Effect of different cleansers on the weight and ion release of removable partial denture: an in vitro study

    Directory of Open Access Journals (Sweden)

    Daniela N.B. Felipucci

    2011-10-01

    Full Text Available OBJECTIVE: Removable partial dentures (RPD require different hygiene care, and association of brushing and chemical cleansing is the most recommended to control biofilm formation. However, the effect of cleansers has not been evaluated in RPD metallic components. The aim of this study was to evaluate in vitro the effect of different denture cleansers on the weight and ion release of RPD. MATERIAL AND METHODS: Five specimens (12x3 mm metallic disc positioned in a 38x18x4 mm mould filled with resin, 7 cleanser agents [Periogard (PE, Cepacol (CE, Corega Tabs (CT, Medical Interporous (MI, Polident (PO, 0.05% sodium hypochlorite (NaOCl, and distilled water (DW (control] and 2 cobalt-chromium alloys [DeguDent (DD, and VeraPDI (VPDI] were used for each experimental situation. One hundred and eighty immersions were performed and the weight was analyzed with a high precision analytic balance. Data were recorded before and after the immersions. The ion release was analyzed using mass spectrometry with inductively coupled plasma. Data were analyzed by two-way ANOVA and Tukey HSD post hoc test at 5% significance level. RESULTS: Statistical analysis showed that CT and MI had higher values of weight loss with higher change in VPDI alloy compared to DD. The solutions that caused more ion release were NaOCl and MI. CONCLUSIONS: It may be concluded that 0.05% NaOCl and Medical Interporous tablets are not suitable as auxiliary chemical solutions for RPD care.

  9. Discrimination of Isomers of Released N- and O-Glycans Using Diagnostic Product Ions in Negative Ion PGC-LC-ESI-MS/MS

    Science.gov (United States)

    Ashwood, Christopher; Lin, Chi-Hung; Thaysen-Andersen, Morten; Packer, Nicolle H.

    2018-03-01

    Profiling cellular protein glycosylation is challenging due to the presence of highly similar glycan structures that play diverse roles in cellular physiology. As the anomericity and the exact linkage type of a single glycosidic bond can influence glycan function, there is a demand for improved and automated methods to confirm detailed structural features and to discriminate between structurally similar isomers, overcoming a significant bottleneck in the analysis of data generated by glycomics experiments. We used porous graphitized carbon-LC-ESI-MS/MS to separate and detect released N- and O-glycan isomers from mammalian model glycoproteins using negative mode resonance activation CID-MS/MS. By interrogating similar fragment spectra from closely related glycan isomers that differ only in arm position and sialyl linkage, product fragment ions for discrimination between these features were discovered. Using the Skyline software, at least two diagnostic fragment ions of high specificity were validated for automated discrimination of sialylation and arm position in N-glycan structures, and sialylation in O-glycan structures, complementing existing structural diagnostic ions. These diagnostic ions were shown to be useful for isomer discrimination using both linear and 3D ion trap mass spectrometers when analyzing complex glycan mixtures from cell lysates. Skyline was found to serve as a useful tool for automated assessment of glycan isomer discrimination. This platform-independent workflow can potentially be extended to automate the characterization and quantitation of other challenging glycan isomers. [Figure not available: see fulltext.

  10. Taste masking of ciprofloxacin by ion-exchange resin and sustain release at gastric-intestinal through interpenetrating polymer network

    Directory of Open Access Journals (Sweden)

    A. Michael Rajesh

    2015-07-01

    Full Text Available The aim of the study was to taste mask ciprofloxacin (CP by using ion-exchange resins (IERs followed by sustain release of CP by forming interpenetrating polymer network (IPN. IERs based on the copolymerization of acrylic acid with different cross linking agents were synthesised. Drug-resin complexes (DRCs with three different ratios of drug to IERs (1:1, 1:2, 1:4 were prepared & evaluated for taste masking by following in vivo and in vitro methods. Human volunteers graded ADC 1:4, acrylic acid-divinyl benzene (ADC-3 resin as tasteless. Characterization studies such as FTIR, SEM, DSC, P-XRD differentiated ADC 1:4, from physical mixture (PM 1:4 and confirmed the formation of complex. In vitro drug release of ADC 1:4 showed complete release of CP within 60 min at simulated gastric fluid (SGF i.e. pH 1.2. IPN beads were prepared with ADC 1:4 by using sodium alginate (AL and sodium alginate-chitosan (AL-CS for sustain release of CP at SGF pH and followed by simulated intestinal fluid (SIF i.e. pH 7.4. FTIR spectra confirmed the formation of IPN beads. The release of CP was sustain at SGF pH (75%. The kinetic model of IPN beads showed the release of CP was non-Fickian diffusion type.

  11. Release of nickel and chromium ions in the saliva of patients with fixed orthodontic appliance: An in-vivo study.

    Science.gov (United States)

    Dwivedi, Anoop; Tikku, Tripti; Khanna, Rohit; Maurya, Rana Pratap; Verma, Geeta; Murthy, R C

    2015-01-01

    Various components of fixed orthodontic appliances are continuously interacting with saliva and other fluids in the mouth releasing various metal ions including nickel and chromium that can cause damaging effects if their concentration exceeds above the toxic dose. To determine and compare the level of nickel and chromium in the saliva of patients undergoing fixed orthodontic treatment at different time periods. The sample of saliva of 13 patients was taken at different time periods that is: Group 1 (before appliance placement), Group II, III, and IV (after 1-week, 1-month, and 3 months of appliance placement respectively). The fixed appliance comprised of brackets, bands, buccal tubes, lingual sheath, transpalatal arch and wires composed of Ni-Ti and stainless steel. The level of ions was determined using graphite furnace atomic absorption spectro-photometry. The data thus obtained were statistically analyzed using SPSS Statistical Analysis Software (Version 15.0). Level of nickel and chromium in saliva was highest in Group II and lowest in Groups I for both the ions. On comparison among different Groups, it was statistically significant for all the groups (<0.001) except between Group III and Group IV. The release of nickel and chromium was maximum at 1-week and then the level gradually declined. These values were well below the toxic dose of these ions. The results should be viewed with caution in subjects with Ni hypersensitivity.

  12. Self-Volatilization Approach to Mesoporous Carbon Nanotube/Silver Nanoparticle Hybrids: The Role of Silver in Boosting Li Ion Storage.

    Science.gov (United States)

    Jiang, Hao; Zhang, Haoxuan; Fu, Yao; Guo, Shaojun; Hu, Yanjie; Zhang, Ling; Liu, Yu; Liu, Honglai; Li, Chunzhong

    2016-01-26

    One of the biggest challenging issues of carbon nanomaterials for Li ion batteries (LIBs) is that they show low initial Coulombic efficiency (CE), leading to a limited specific capacity. Herein, we demonstrate a simple template self-volatilization strategy for in situ synthesis of mesoporous carbon nanotube/Ag nanoparticle (NP) hybrids (Ag-MCNTs) to boost the LIBs' performance. The key concept of Ag-MCNTs for enhancing LIBs is that a small trace of Ag NPs on MCNTS can greatly restrict the formation of a thicker solid electrolyte interphase film, which has been well verified by both transmission electron microscopy results and quantum density functional theory calculations, leading to the highest initial CE in all the reported carbon nanomaterials. This uncovered property of Ag NPs from Ag-MCNTs makes them exhibit a very high reversible capacity of 1637 mAh g(-1) after 400 discharge/charge cycles at 100 mA g(-1), approximately 5 times higher than the theoretical value of a graphite anode (372 mAh g(-1)), excellent rate capability, and long cycle life.

  13. Irradiation with visible light enhances the antibacterial toxicity of silver nanoparticles produced by laser ablation

    Science.gov (United States)

    Ratti, Matthew; Naddeo, J. J.; Tan, Yuying; Griepenburg, Julianne C.; Tomko, John; Trout, Cory; O'Malley, Sean M.; Bubb, Daniel M.; Klein, Eric A.

    2016-04-01

    The rise of antibiotic-resistant bacteria is a rapidly growing global health concern. According to the Center for Disease Control, approximately 2 million illnesses and 23,000 deaths per year occur in the USA due to antibiotic resistance. In recent years, there has been a surge in the use of metal nanoparticles as coatings for orthopedic implants, wound dressings, and food packaging, due to their antimicrobial properties. In this report, we demonstrate that the antibacterial efficacy of silver nanoparticles (AgNPs) is enhanced with exposure to light from the visible spectrum. We find that the increased toxicity is due to augmented silver ion release and bacterial uptake. Interestingly, silver ion toxicity does not appear to depend on the formation of reactive oxygen species. Our findings provide a novel paradigm for using light to regulate the toxicity of AgNPs which may have a significant impact in the development of new antimicrobial therapeutics.

  14. Release of titanium ions from an implant surface and their effect on cytokine production related to alveolar bone resorption

    International Nuclear Information System (INIS)

    Wachi, Takanori; Shuto, Takahiro; Shinohara, Yoshinori; Matono, Yoshinari; Makihira, Seicho

    2015-01-01

    Although interest in peri-implant mucositis and peri-implantitis has recently been increasing, the mechanisms driving these diseases remain unknown. Here, the effects of titanium ions on the inflammation and bone resorption around an implant were investigated. First, the accumulated amount of Ti ions released into gingival and bone tissues from an implant exposed to sodium fluoride solution was measured using inductively coupled plasma mass spectrometry. Next, the cellular responses in gingival and bone tissues to Ti ions and/or Porphyromonas gingivalis-lipopolysaccharide (P. gingivalis-LPS) were assessed using a rat model. More Ti ions were detected in the gingival tissues around an implant after treatment with sodium fluoride (pH 4.2) than in its absence, which suggests that the fluoride corroded the implant surface under salivary buffering capacity. The injection of Ti ions (9 ppm) significantly increased the mRNA expression and protein accumulation of chemokine (C–C motif) ligand 2, as well as the ratio of receptor activator of nuclear factor-κB ligand to osteoprotegerin, in rat gingival tissues exposed to P. gingivalis-LPS in a synergistic manner. In addition, the enhanced localization of toll-like receptor 4, which is an LPS receptor, was observed in gingival epithelium loaded with Ti ions (9 ppm). These data suggest that Ti ions may be partly responsible for the infiltration of monocytes and osteoclast differentiation by increasing the sensitivity of gingival epithelial cells to microorganisms in the oral cavity. Therefore, Ti ions may be involved in the deteriorating effects of peri-implant mucositis, which can develop into peri-implantitis accompanied by alveolar bone resorption

  15. Adduct formation of ionic and nanoparticular silver with amino acids and glutathione

    International Nuclear Information System (INIS)

    Blaske, Franziska; Stork, Lisa; Sperling, Michael; Karst, Uwe

    2013-01-01

    To investigate the interaction of ionic and nanoparticular silver with amino acids and small peptides, an electrospray ionization time-of-flight mass spectrometry method was developed. Monomeric and oligomeric silver adducts were formed with amino acids including cysteine (Cys), methionine, histidine, lysine, or the tripeptide glutathione (GSH). The obtained spectra for ionic silver show clusters in different ratios between Ag + and the reaction partners (X) including [Ag n X m − (n + 1)H] − (n = 1–4, m = 1–3). Regarding Cys, adduct clusters up to n = 5 and m = 4 were observed as well. Considering silver–GSH interactions, even doubly charged oligomers occur generating [Ag (a+1) GSH a − (a + 3)H] 2− (a = 5–7) and [Ag b GSH b − (b + 2)H] 2− (b = 4–8) ions. 1 H NMR data of free GSH compared to that after treatment with Ag + confirm sulfur–metal interactions due to changing chemical shifts for the protons located adjacent to the thiol group. Density functional theory calculations for silver–GSH clusters may explain the formation of experimentally recorded large clusters due to cooperative effects between silver and carboxylic acid side chains. Both sets of experiments indicate the presence of these adducts in the liquid phase. For silver nanoparticles, the respective data confirm the release of silver ions and the subsequent adduct formation

  16. Optimization of ISOL targets based on Monte-Carlo simulations of ion release curves

    International Nuclear Information System (INIS)

    Mustapha, B.; Nolen, J.A.

    2003-01-01

    A detailed model for simulating release curves from ISOL targets has been developed. The full 3D geometry is implemented using Geant-4. Produced particles are followed individually from production to release. The delay time is computed event by event. All processes involved: diffusion, effusion and decay are included to obtain the overall release curve. By fitting to the experimental data, important parameters of the release process (diffusion coefficient, sticking time, ...) are extracted. They can be used to improve the efficiency of existing targets and design new ones more suitable to produce beams of rare isotopes

  17. Optimization of ISOL targets based on Monte-Carlo simulations of ion release curves

    CERN Document Server

    Mustapha, B

    2003-01-01

    A detailed model for simulating release curves from ISOL targets has been developed. The full 3D geometry is implemented using Geant-4. Produced particles are followed individually from production to release. The delay time is computed event by event. All processes involved: diffusion, effusion and decay are included to obtain the overall release curve. By fitting to the experimental data, important parameters of the release process (diffusion coefficient, sticking time, ...) are extracted. They can be used to improve the efficiency of existing targets and design new ones more suitable to produce beams of rare isotopes.

  18. Antibacterial effects of silver-doped hydroxyapatite thin films sputter deposited on titanium

    International Nuclear Information System (INIS)

    Trujillo, Nathan A.; Oldinski, Rachael A.; Ma, Hongyan; Bryers, James D.; Williams, John D.; Popat, Ketul C.

    2012-01-01

    Since many orthopedic implants fail as a result of loosening, wear, and inflammation caused by repeated loading on the joints, coatings such as hydroxyapatite (HAp) on titanium with a unique topography have been shown to improve the interface between the implant and the natural tissue. Another serious problem with long-term or ideally permanent implants is infection. It is important to prevent initial bacterial colonization as existing colonies have the potential to become encased in an extracellular matrix polymer (biofilm) that is resistant to antibacterial agents. In this study, plasma-based ion implantation was used to examine the effects of pre-etching on plain titanium. Topographical changes to the titanium samples were examined and compared via scanning electron microscopy. Hydroxyapatite and silver-doped hydroxyapatite thin films were then sputter deposited on titanium substrates etched at − 700 eV. For silver-doped films, two concentrations of silver (∼ 0.5 wt.% and ∼ 1.5 wt.%) were used. Silver concentrations in the film were determined using energy dispersive X-ray spectroscopy. Hydroxyapatite film thicknesses were determined by measuring the surface profile using contact profilometry. Staphylococcus epidermidis and Pseudomonas aeruginosa adhesion studies were performed on plain titanium, titanium coated with hydroxyapatite, titanium coated with ∼ 0.5 wt.% silver-doped hydroxyapatite, and titanium coated with ∼ 1.5 wt.% silver-doped hydroxyapatite. Results indicate that less bacteria adhered to surfaces containing hydroxyapatite and silver; further, as the hydroxyapatite films delaminated, silver ions were released which killed bacteria in suspension. - Highlights: ► We have developed a combination of plasma-based ion implantation and ion beam sputter deposition technique. ► Silver-doped hydroxyapatite thin films on titanium were developed. ► The thin films showed the ability to control the concentration of silver that is doped within the

  19. Structural and optical modification in 4H-SiC following 30 keV silver ion irradiation

    Science.gov (United States)

    Kaushik, Priya Darshni; Aziz, Anver; Siddiqui, Azher M.; Lakshmi, G. B. V. S.; Syväjärvi, Mikael; Yakimova, Rositsa; Yazdi, G. Reza

    2018-05-01

    The market of high power, high frequency and high temperature based electronic devices is captured by SiC due to its superior properties like high thermal conductivity and high sublimation temperature and also due to the limitation of silicon based electronics in this area. There is a need to investigate effect of ion irradiation on SiC due to its application in outer space as outer space is surrounded both by low and high energy ion irradiations. In this work, effect of low energy ion irradiation on structural and optical property of 4H-SiC is investigated. ATR-FTIR is used to study structural modification and UV-Visible spectroscopy is used to study optical modifications in 4H-SiC following 30 keV Ag ion irradiation. FTIR showed decrease in bond density of SiC along the ion path (track) due to the creation of point defects. UV-Visible absorption spectra showed decrease in optical band gap from 3.26 eV to 2.9 eV. The study showed degradation of SiC crystallity and change in optical band gap following low energy ion irradiation and should be addressed while fabricationg devices based on SiC for outer space application. Additionally, this study provides a platform for introducing structural and optical modification in 4H-SiC using ion beam technology in a controlled manner.

  20. Incorporating water-release and lateral protein interactions in modeling equilibrium adsorption for ion-exchange chromatography.

    Science.gov (United States)

    Thrash, Marvin E; Pinto, Neville G

    2006-09-08

    The equilibrium adsorption of two albumin proteins on a commercial ion exchanger has been studied using a colloidal model. The model accounts for electrostatic and van der Waals forces between proteins and the ion exchanger surface, the energy of interaction between adsorbed proteins, and the contribution of entropy from water-release accompanying protein adsorption. Protein-surface interactions were calculated using methods previously reported in the literature. Lateral interactions between adsorbed proteins were experimentally measured with microcalorimetry. Water-release was estimated by applying the preferential interaction approach to chromatographic retention data. The adsorption of ovalbumin and bovine serum albumin on an anion exchanger at solution pH>pI of protein was measured. The experimental isotherms have been modeled from the linear region to saturation, and the influence of three modulating alkali chlorides on capacity has been evaluated. The heat of adsorption is endothermic for all cases studied, despite the fact that the net charge on the protein is opposite that of the adsorbing surface. Strong repulsive forces between adsorbed proteins underlie the endothermic heat of adsorption, and these forces intensify with protein loading. It was found that the driving force for adsorption is the entropy increase due to the release of water from the protein and adsorbent surfaces. It is shown that the colloidal model predicts protein adsorption capacity in both the linear and non-linear isotherm regions, and can account for the effects of modulating salt.

  1. Investigating the role of ion-pair strategy in regulating nicotine release from patch: Mechanistic insights based on intermolecular interaction and mobility of pressure sensitive adhesive.

    Science.gov (United States)

    Li, Qiaoyun; Wan, Xiaocao; Liu, Chao; Fang, Liang

    2018-07-01

    The aim of this study was to prepare a drug-in-adhesive patch of nicotine (NIC) and use ion-pair strategy to regulate drug delivery rate. Moreover, the mechanism of how ion-pair strategy regulated drug release was elucidated at molecular level. Formulation factors including pressure sensitive adhesives (PSAs), drug loading and counter ions (C 4 , C 6 , C 8 , C 10 , and C 12 ) were screened. In vitro release experiment and in vitro transdermal experiment were conducted to determine the rate-limiting step in drug delivery process. FT-IR and molecular modeling were used to characterize the interaction between drug and PSA. Thermal analysis and rheology study were conducted to investigate the mobility variation of PSA. The optimized patch prepared with NIC-C 8 had the transdermal profile fairly close to that of the commercial product (p > 0.05). The release rate constants (k) of NIC, NIC-C 4 and NIC-C 10 were 21.1, 14.4 and 32.4, respectively. Different release rates of NIC ion-pair complexes were attributed to the dual effect of ion-pair strategy on drug release. On one hand, ion-pair strategy enhanced the interaction between drug and PSA, which inhibited drug release. On the other hand, using ion-pair strategy improved the mobility of PSA, which facilitated drug release. Drug release behavior was determined by combined effect of two aspects above. These conclusions provided a new idea for us to regulate drug release behavior from patch. Copyright © 2018 Elsevier B.V. All rights reserved.

  2. INTERACTION OF SILVER MOLECULAR CLUSTERS, INTRODUCED BY LOW-TEMPERATURE ION EXCHANGE METHOD, WITH NANOPARTICLES OF CdS IN FLUORINE PHOSPHATE GLASSES

    Directory of Open Access Journals (Sweden)

    N. D. Grazhdanov

    2015-09-01

    Full Text Available Glasses with metallic and semi-conductive nano-particles appear to be perspective non-linear and luminescent materials of photonics. It was shown in theory that composite optical materials containing semi-conductive CdS-core with Ag shell (or vice versa are optimal for enhancement of non-linear Kerr effect. Interaction of such an ensemble of particles leads to the forming of Ag island structures on the CdS particle, and formation of acanthite Ag2S on the two phases border (CdS-Ag is minimal. In glasses synthesis of CdS quantum dots occurred due to thermal treatment close to glass transition temperature; introduction of silver was realized by low-temperature ion exchange (LIE. The main object of this work is investigation of Ag+ -LIE effect on the growth of CdS nano-particles. Two glasses were explored in this work: without CdS (glass 1 and with CdS (glass 2, processed by LIE at the temperature of 320°С for 10, 20 and 30 minutes and subsequent heat treatment at temperatures of 410°С and 420°С. In case of glass 1, intensive luminescence appears as a result of LIE, and subsequent heat treatment results in surface resonance at λ=410 nm. In case of glass 2, absorbance spectra change appears that is specific for formation of acanthite and weak luminescence shifting to long-wavelength region (from 550 to 700 nm as a result of applying LIE and heat treatment. It indicates the growth of CdS quantum dots. Experiment has shown that quantum efficiency increases to 70% for glass 2 containing CdS quantum dots without LIE, while glass that contains silver shows steep decrease of quantum efficiency to 0%. That decrease is caused by formation of acanthite Ag2S on the surface of CdS quantum dot.

  3. Oxidative decarboxylation of glycolic and phenylacetic acids with cerium(4) catalyzed by silver ions in the sulfuric acid media

    International Nuclear Information System (INIS)

    Venkatesvar Rao, G.; Nagardzhun Rao, Ch.; Sajprakash, P.K.

    1981-01-01

    Oxidative decarboxylation of glycolic and phenylacetic acids by cerium (4) in the presence of Ag + ions is studied. The Ce(4) order equals 1, glycolic acid order in the absence of a catalyst also equals 1 and is fractional (0.5) for a catalytic reaction. The phenylacetic acid order is fractional (0.75). The Ag + ion reaction order is fractional and constitutes 0.32 for glycolic and 0.36 for phenylacetic acids. The reaction mechanism is proposed [ru

  4. Hollow-fiber flow field-flow fractionation and multi-angle light scattering investigation of the size, shape and metal-release of silver nanoparticles in aqueous medium for nano-risk assessment.

    Science.gov (United States)

    Marassi, Valentina; Casolari, Sonia; Roda, Barbara; Zattoni, Andrea; Reschiglian, Pierluigi; Panzavolta, Silvia; Tofail, Syed A M; Ortelli, Simona; Delpivo, Camilla; Blosi, Magda; Costa, Anna Luisa

    2015-03-15

    Due to the increased use of silver nanoparticles in industrial scale manufacturing, consumer products and nanomedicine reliable measurements of properties such as the size, shape and distribution of these nano particles in aqueous medium is critical. These properties indeed affect both functional properties and biological impacts especially in quantifying associated risks and identifying suitable risk-mediation strategies. The feasibility of on-line coupling of a fractionation technique such as hollow-fiber flow field flow fractionation (HF5) with a light scattering technique such as MALS (multi-angle light scattering) is investigated here for this purpose. Data obtained from such a fractionation technique and its combination thereof with MALS have been compared with those from more conventional but often complementary techniques e.g. transmission electron microscopy, dynamic light scattering, atomic absorption spectroscopy, and X-ray fluorescence. The combination of fractionation and multi angle light scattering techniques have been found to offer an ideal, hyphenated methodology for a simultaneous size-separation and characterization of silver nanoparticles. The hydrodynamic radii determined by fractionation techniques can be conveniently correlated to the mean average diameters determined by multi angle light scattering and reliable information on particle morphology in aqueous dispersion has been obtained. The ability to separate silver (Ag(+)) ions from silver nanoparticles (AgNPs) via membrane filtration during size analysis is an added advantage in obtaining quantitative insights to its risk potential. Most importantly, the methodology developed in this article can potentially be extended to similar characterization of metal-based nanoparticles when studying their functional effectiveness and hazard potential. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. The influence of metallic ions from CoCr28Mo6 on the osteogenic differentiation and cytokine release of human osteoblasts

    Directory of Open Access Journals (Sweden)

    Jonitz-Heincke A

    2015-09-01

    Full Text Available Inflammatory reactions associated with osteolysis and implant loosening can be the result of generated CoCr particles and the simultaneous release of ions, which are the consequence of wear at the articulating surfaces of metallic implants. By now, there is little knowledge about the influence of CoCr ions on the viability of human osteoblasts (hOB.

  6. Dynamic electrochemical measurement of chloride ions

    NARCIS (Netherlands)

    Abbas, Yawar; de Graaf, Derk B.; Olthuis, Wouter; van den Berg, Albert

    2016-01-01

    This protocol describes the dynamic measurement of chloride ions using the transition time of a silver silver chloride (Ag/AgCl) electrode. Silver silver chloride electrode is used extensively for potentiometric measurement of chloride ions concentration in electrolyte. In this measurement,

  7. Catalytic Micromotors Moving Near Polyelectrolyte-Modified Substrates: The Roles of Surface Charges, Morphology, and Released Ions.

    Science.gov (United States)

    Wei, Mengshi; Zhou, Chao; Tang, Jinyao; Wang, Wei

    2018-01-24

    Synthetic microswimmers, or micromotors, are finding potential uses in a wide range of applications, most of which involve boundaries. However, subtle yet important effects beyond physical confinement on the motor dynamics remain less understood. In this letter, glass substrates were functionalized with positively and negatively charged polyelectrolytes, and the dynamics of micromotors moving close to the modified surfaces was examined. Using acoustic levitation and numerical simulation, we reveal how the speed of a chemically propelled micromotor slows down significantly near a polyelectrolyte-modified surface by the combined effects of surface charges, surface morphology, and ions released from the films.

  8. Pelepasan ion nikel dan kromium kawat Australia dan stainless steel dalam saliva buatan (The release of nickel and chromium ions from Australian wire and stainless steel in artificial saliva)

    OpenAIRE

    Nolista Indah Rasyid; Pinandi Sri Pudyani; JCP Heryumani

    2014-01-01

    Background: Fixed orthodontic treatment needs several types of wire to produce biomechanical force to move teeth. The use orthodontic wire within the mouth interacts with saliva, causing the release of nickel and chromium ions. Purpose: The study was aimed to examine the effect of immersion time in artificial saliva between special type of Australian wire and stainless steel on the release of nickel and chromium ions. Methods: Thirty special type Australian wires and 30 stainless steel wires ...

  9. Antimicrobial Properties of Diamond-Like Carbon/Silver Nanocomposite Thin Films Deposited on Textiles: Towards Smart Bandages

    Directory of Open Access Journals (Sweden)

    Tadas Juknius

    2016-05-01

    Full Text Available In the current work, a new antibacterial bandage was proposed where diamond-like carbon with silver nanoparticle (DLC:Ag-coated synthetic silk tissue was used as a building block. The DLC:Ag structure, the dimensions of nanoparticles, the silver concentration and the silver ion release were studied systematically employing scanning electron microscopy, energy dispersive X-ray spectroscopy and atomic absorption spectroscopy, respectively. Antimicrobial properties were investigated using microbiological tests (disk diffusion method and spread-plate technique. The DLC:Ag layer was stabilized on the surface of the bandage using a thin layer of medical grade gelatin and cellulose. Four different strains of Staphylococcus aureus extracted from humans’ and animals’ infected wounds were used. It is demonstrated that the efficiency of the Ag+ ion release to the aqueous media can be increased by further RF oxygen plasma etching of the nanocomposite. It was obtained that the best antibacterial properties were demonstrated by the plasma-processed DLC:Ag layer having a 3.12 at % Ag surface concentration with the dominating linear dimensions of nanoparticles being 23.7 nm. An extra protective layer made from cellulose and gelatin with agar contributed to the accumulation and efficient release of silver ions to the aqueous media, increasing bandage antimicrobial efficiency up to 50% as compared to the single DLC:Ag layer on textile.

  10. Antimicrobial Properties of Diamond-Like Carbon/Silver Nanocomposite Thin Films Deposited on Textiles: Towards Smart Bandages

    Science.gov (United States)

    Juknius, Tadas; Ružauskas, Modestas; Tamulevičius, Tomas; Šiugždinienė, Rita; Juknienė, Indrė; Vasiliauskas, Andrius; Jurkevičiūtė, Aušrinė; Tamulevičius, Sigitas

    2016-01-01

    In the current work, a new antibacterial bandage was proposed where diamond-like carbon with silver nanoparticle (DLC:Ag)-coated synthetic silk tissue was used as a building block. The DLC:Ag structure, the dimensions of nanoparticles, the silver concentration and the silver ion release were studied systematically employing scanning electron microscopy, energy dispersive X-ray spectroscopy and atomic absorption spectroscopy, respectively. Antimicrobial properties were investigated using microbiological tests (disk diffusion method and spread-plate technique). The DLC:Ag layer was stabilized on the surface of the bandage using a thin layer of medical grade gelatin and cellulose. Four different strains of Staphylococcus aureus extracted from humans’ and animals’ infected wounds were used. It is demonstrated that the efficiency of the Ag+ ion release to the aqueous media can be increased by further RF oxygen plasma etching of the nanocomposite. It was obtained that the best antibacterial properties were demonstrated by the plasma-processed DLC:Ag layer having a 3.12 at % Ag surface concentration with the dominating linear dimensions of nanoparticles being 23.7 nm. An extra protective layer made from cellulose and gelatin with agar contributed to the accumulation and efficient release of silver ions to the aqueous media, increasing bandage antimicrobial efficiency up to 50% as compared to the single DLC:Ag layer on textile. PMID:28773494

  11. Isotopic study of the comparative uptake and release of ions by deciduous and permanent dental enamel

    International Nuclear Information System (INIS)

    Tetteh, G.K.

    1975-01-01

    A comparative study of the uptake and release of calcium, orthophosphate, strontium and sodium from decidus and permanent dental enamel has been made using radioactive techniques. The rates of uptake and release of orthophosphate, strontium and sodium were observed to be greater in deciduous than in permanent enamel. However, for calcium, the rate of uptake was observed to be greater in the deciduous than in the permanent enamel but the rate of release was observed to be smaller in the deciduous enamel. These results in conjunction with the findings of Tetteh (1974) suggest that most of the calcification in the early stages of development of dental enamel is by a hetero-ionic exchange. (author) [fr

  12. Isotopic study of the comparative uptake and release of ions by deciduous and permanent dental enamel

    Energy Technology Data Exchange (ETDEWEB)

    Tetteh, G K [Department of Physics, University of Ghana,Legon

    1975-04-01

    A comparative study of the uptake and release of calcium, orthophosphate, strontium and sodium from decidus and permanent dental enamel has been made using radioactive techniques. The rates of uptake and release of orthophosphate, strontium and sodium were observed to be greater in deciduous than in permanent enamel. However, for calcium, the rate of uptake was observed to be greater in the deciduous than in the permanent enamel but the rate of release was observed to be smaller in the deciduous enamel. These results in conjunction with the findings of Tetteh (1974) suggest that most of the calcification in the early stages of development of dental enamel is by a hetero-ionic exchange.

  13. Incorporation of zinc oxide to dispersions of biopolymers and release of the metallic ion in vitro

    International Nuclear Information System (INIS)

    Barreto, Marina S.R.; Ferreira, Willian H.; Andrade, Cristina T.

    2015-01-01

    Zinc oxide (ZnO) nanoparticles, obtained from a commercial product, were dispersed in different biopolymers, to be added to piglet feeds. The resulting products, prepared with sodium alginate (SA), chitosan (CH) and low methoxyl pectin (LMP) were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The release of Zn"2"+ was investigated under simulated conditions of the gastrointestinal tract of piglets, and analyzed by atomic absorption spectroscopy (AA). The results showed that the structural factors, which have influence on the biopolymer/ZnO interactions, govern the behavior of Zn"2"+ release. (author)

  14. Ion beam assisted synthesis of nano-crystals in glasses (silver and lead chalcogenides); Synthese assistee par faisceau d'ions d'agregats dans les verres (argent et chalcogenures de plomb)

    Energy Technology Data Exchange (ETDEWEB)

    Espiau de Lamaestre, R

    2005-04-15

    This work deals with the interest in ion beams for controlling nano-crystals synthesis in glasses. We show two different ways to reach this aim, insisting on importance of redox phenomena induced by the penetration and implantation of ions in glasses. We first show that we can use the great energy density deposited by the ions to tailor reducing conditions, favorable to metallic nano-crystal precipitation. In particular, we show that microscopic mechanism of radiation induced silver precipitation in glasses are analogous to the ones of classical photography. Ion beams can also be used to overcome supersaturation of elements in a given matrix. In this work, we synthesized lead chalcogenide nano-crystals (PbS, PbSe, PbTe) whose optical properties are interesting for telecommunication applications. We demonstrate the influence of complex chalcogenide chemistry in oxide glasses, and its relationship with the observed loss of growth control when nano-crystals are synthesized by sequential implantation of Pb and S in pure silica. As a consequence of this understanding, we demonstrate a novel and controlled synthesis of PbS nano-crystals, consisting in implanting sulfur into a Pb-containing glass, before annealing. Choice of glass composition provides a better control of precipitation physico-chemistry, whereas the use of implantation allows high nano-crystal volume fractions to be reached. Our study of IR emission properties of these nano-crystals shows a very high excitation cross section, and evidence for a 'dark exciton' emitting level. (author)

  15. Immobilization and bonding scheme of radioactive iodine-129 in silver tellurite glass

    Science.gov (United States)

    Lee, Cheong Won; Pyo, Jae-Young; Park, Hwan-Seo; Yang, Jae Hwan; Heo, Jong

    2017-08-01

    Silver tellurite glasses with melting temperatures disposal site. Iodine waste loading in glasses was as high as 12.64 wt% of all metallic elements and 11.21 wt% including oxygen. Normalized elemental releases obtained from the product consistency test were well below US regulation of 2 g/m2. Iodines are surrounded by four Ag+ ions forming [Ag4I]3+ units that are further connected to tellurite network through bonds with non-bridging oxygens.

  16. Detection of mercury ions using silver telluride nanoparticles as a substrate and recognition element through surface-enhanced Raman scattering

    Directory of Open Access Journals (Sweden)

    Chia-Wei eWang

    2013-10-01

    Full Text Available In this paper we unveil a new sensing strategy for sensitive and selective detection of Hg2+ through surface-enhanced Raman scattering (SERS using Ag2Te nanoparticles (NPs as a substrate and recognition element and rhodamine 6G (R6G as a reporter. Ag2Te NPs prepared from tellurium dioxide and silver nitrate and hydrazine in aqueous solution containing sodium dodecyl sulfate at 90ºC with an average size of 26.8 ± 4.1 nm (100 counts have strong SERS activity. The Ag2Te substrate provides strong SERS signals of R6G with an enhancement factor of 3.6 × 105 at 1360 cm-1, which is comparable to Ag NPs. After interaction of Ag2Te NPs with Hg2+, some HgTe NPs are formed, leading to decreases in the SERS signal of R6G, mainly because HgTe NPs relative to Ag2Te NPs have weaker SERS activity. Under optimum conditions, this SERS approach using Ag2Te as substrates is selective for the detection of Hg2+, with a limit of detection of 3 nM and linearity over 10-150 nM. The practicality of this approach has been validated for the determination of the concentrations of spiked Hg2+ in a pond water sample.

  17. Research into releasing inorganic phosphate and base from 5'-dTMP irradiated by a low energy ion beam

    International Nuclear Information System (INIS)

    Shao Chunlin; Yu Zengliang

    1994-01-01

    Research into radiation damage of nucleotide is an important area in radiation biology. In this paper, the yield of inorganic phosphate and base released from 5'-dTMP irradiated by a 30 keV N + ion beam was investigated in several aspects. The effect of particle fluence on yield and the influence of treatment with 0.1 N NaOH was deduced. By analysis, it is known that the alkali treatment not only increases the yield of inorganic phosphate, but also damages and splits the base released from irradiated 5'-dTMP. When the irradiated samples are treated by 0.1 N NaOH immediately, the yield of inorganic phosphate is increased by a factor of 1.7 and the concentration of base decreased to half of the original value. But the yield of inorganic phosphate could be increased by a factor of 2.8 after 40 min of alkali treatment. On the other hand, when 5'dTMP was irradiated by the ion beam, the G(Pi) obtained was above 0.44, higher than with γ-radiation. (Author)

  18. Antibacterial and anti-adhesion effects of the silver nanoparticles-loaded poly(L-lactide) fibrous membrane

    International Nuclear Information System (INIS)

    Liu, Shen; Zhao, Jingwen; Ruan, Hongjiang; Wang, Wei; Wu, Tianyi; Cui, Wenguo; Fan, Cunyi

    2013-01-01

    The complications of tendon injury are frequently compromised by peritendinous adhesions and tendon sheath infection. Physical barriers for anti-adhesion may increase the incidence of postoperative infection. This study was designed to evaluate the potential of silver nanoparticles (AgNPs)-loaded poly(L-lactide) (PLLA) electrospun fibrous membranes to prevent adhesion formation and infection. Results of an in vitro drug release study showed that a burst release was followed by sustained release from electrospun fibrous membranes with a high initial silver content. Fewer fibroblasts adhered to and proliferated on the AgNP-loaded PLLA electrospun fibrous membranes compared with pure PLLA electrospun fibrous membrane. In the antibacterial test, the AgNP-loaded PLLA electrospun fibrous membranes can prevent the adhesion of Gram-positive Staphylococcus aureus and Staphylococcus epidermidis and Gram-negative Pseudomonas aeruginosa. Taken together, these results demonstrate that AgNP-loaded PLLA electrospun fibrous membranes have the convenient practical medical potential of reduction of infection and adhesion formation after tendon injury. - Highlights: ► Silver nanoparticles are directly electrospun into PLLA fibrous membrane. ► Long-lasting release of Ag + ions is achieved. ► Cytotoxicity of silver ions benefits the anti-proliferation of physical barriers. ► Broad anti-microbial effect of drug-loaded fibrous membrane is revealed. ► Antibacterial and anti-adhesion effects of the physical barriers are combined

  19. Differential Regulation of the Nodulation Zone by Silver Ions, L--(2-Amino-Ethoxyvinyl-Glycine, and the skl Mutation in Medicago truncatula

    Directory of Open Access Journals (Sweden)

    JOKO PRAYITNO

    2010-03-01

    Full Text Available Nodule formation in Rhizobium-legume symbiosis is negatively regulated by ethylene. Ethylene inhibitors such as L--(2-amino-ethoxyvinyl-glycine (AVG and silver ions (Ag+, the ethylene-insensitive sickle mutant, and transgenic plants were used to study ethylene-mediated responses in nodulation. The mode of action of ethylene inhibitors AVG and Ag+, and the skl mutation occur at different steps in ethylene biosynthesis and perception. Their effects on root growth and nodulation phenotypes, in particular nodule distribution along the primary root, were compared in this study. Ag+ and AVG treatments showed similar root growth responses to skl mutant. However, nodule distribution in the hypernodulating skl mutant is different from that of wild-type plants grown on either AVG or Ag+. AVG increased nodule numbers and widened the nodulation zone, while the skl mutant had an increased number of nodules within the susceptible zone of nodulation. Ag+ reduced nodule numbers, restricted the nodulation zone, and restored the nodulation phenotype of skl to that of the wild type.

  20. Removal of silver nanoparticles by coagulation processes

    International Nuclear Information System (INIS)

    Sun, Qian; Li, Yan; Tang, Ting; Yuan, Zhihua; Yu, Chang-Ping

    2013-01-01

    Highlights: • This study investigated the removal of AgNP suspensions by four regular coagulants. • The optimal removal efficiencies for the four coagulants were achieved at pH 7.5. • The removal efficiency of AgNPs was affected by the natural water characteristics. • TEM and XRD showed that AgNPs or silver-containing NPs were adsorbed onto the flocs. -- Abstract: Commercial use of silver nanoparticles (AgNPs) will lead to a potential route for human exposure via potable water. Coagulation followed by sedimentation, as a conventional technique in the drinking water treatment facilities, may become an important barrier to prevent human from AgNP exposures. This study investigated the removal of AgNP suspensions by four regular coagulants. In the aluminum sulfate and ferric chloride coagulation systems, the water parameters slightly affected the AgNP removal. However, in the poly aluminum chloride and polyferric sulfate coagulation systems, the optimal removal efficiencies were achieved at pH 7.5, while higher or lower of pH could reduce the AgNP removal. Besides, the increasing natural organic matter (NOM) would reduce the AgNP removal, while Ca 2+ and suspended solids concentrations would also affect the AgNP removal. In addition, results from the transmission electron microscopy and X-ray diffraction showed AgNPs or silver-containing nanoparticles were adsorbed onto the flocs. Finally, natural water samples were used to validate AgNP removal by coagulation. This study suggests that in the case of release of AgNPs into the source water, the traditional water treatment process, coagulation/sedimentation, can remove AgNPs and minimize the silver ion concentration under the well-optimized conditions

  1. Highly selective and sensitive paper-based colorimetric sensor using thiosulfate catalytic etching of silver nanoplates for trace determination of copper ions.

    Science.gov (United States)

    Chaiyo, Sudkate; Siangproh, Weena; Apilux, Amara; Chailapakul, Orawon

    2015-03-25

    A novel, highly selective and sensitive paper-based colorimetric sensor for trace determination of copper (Cu(2+)) ions was developed. The measurement is based on the catalytic etching of silver nanoplates (AgNPls) by thiosulfate (S2O3(2-)). Upon the addition of Cu(2+) to the ammonium buffer at pH 11, the absorption peak intensity of AuNPls/S2O3(2-) at 522 nm decreased and the pinkish violet AuNPls became clear in color as visible to the naked eye. This assay provides highly sensitive and selective detection of Cu(2+) over other metal ions (K(+), Cr(3+), Cd(2+), Zn(2+), As(3+), Mn(2+), Co(2+), Pb(2+), Al(3+), Ni(2+), Fe(3+), Mg(2+), Hg(2+) and Bi(3+)). A paper-based colorimetric sensor was then developed for the simple and rapid determination of Cu(2+) using the catalytic etching of AgNPls. Under optimized conditions, the modified AgNPls coated at the test zone of the devices immediately changes in color in the presence of Cu(2+). The limit of detection (LOD) was found to be 1.0 ng mL(-1) by visual detection. For semi-quantitative measurement with image processing, the method detected Cu(2+) in the range of 0.5-200 ng mL(-1)(R(2)=0.9974) with an LOD of 0.3 ng mL(-1). The proposed method was successfully applied to detect Cu(2+) in the wide range of real samples including water, food, and blood. The results were in good agreement according to a paired t-test with results from inductively coupled plasma-optical emission spectrometry (ICP-OES). Copyright © 2015. Published by Elsevier B.V.

  2. Silver niobates

    International Nuclear Information System (INIS)

    Tanirbergenov, B.; Rozhenko, S.P.

    1979-01-01

    By means of determination of residual concentrations and pH measurements investigated are the AgNO 3 -KNbO 3 -H 2 O, AgNO 3 -K 3 NbO 4 -H 2 O, AgNO 3 -K 8 Nb 16 O 19 -H 2 O systems and established is formation of meta-, ortho-and hexaniobates of silver. AgNbO 3 x H 2 O, Ag 8 Nb 6 O 19 x 6H 2 O and Ag 3 NbO 3 x 2.5H 2 O are separated from aqueous solution. Using the methods of differential-thermal, thermogravimetric and X-ray-phase analyses it is shown that silver metaniobate transforms into the crystal state at 530 deg C. Ortho- and hexaniobate of silver decompose at 500 deg C with formation of silver metaniobate and metal silver

  3. Titanium carbide-carbon porous nanocomposite materials for radioactive ion beam production: processing, sintering and isotope release properties

    CERN Document Server

    AUTHOR|(CDS)2081922; Stora, Thierry

    2017-01-26

    The Isotope Separator OnLine (ISOL) technique is used at the ISOLDE - Isotope Separator OnLine DEvice facility at CERN, to produce radioactive ion beams for physics research. At CERN protons are accelerated to 1.4 GeV and made to collide with one of two targets located at ISOLDE facility. When the protons collide with the target material, nuclear reactions produce isotopes which are thermalized in the bulk of the target material grains. During irradiation the target is kept at high temperatures (up to 2300 °C) to promote diffusion and effusion of the produced isotopes into an ion source, to produce a radioactive ion beam. Ti-foils targets are currently used at ISOLDE to deliver beams of K, Ca and Sc, however they are operated at temperatures close to their melting point which brings target degradation, through sintering and/or melting which reduces the beam intensities over time. For the past 10 years, nanostructured target materials have been developed and have shown improved release rates of the produced i...

  4. Silver ion modulated CdS quantum dots for highly selective detection of trace Hg{sup 2+}

    Energy Technology Data Exchange (ETDEWEB)

    Uppa, Yuwapon; Kulchat, Sirinan; Ngamdee, Kessarin; Pradublai, Kaewklao [Materials Chemistry Research Unit, Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand); Tuntulani, Thawatchai [Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330 (Thailand); Ngeontae, Wittaya, E-mail: wittayange@kku.ac.th [Materials Chemistry Research Unit, Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand); Research Center for Environmental and Hazardous Substance Management, Khon Kaen University, Khon Kaen 40002 (Thailand); Center of Excellence for Environmental and Hazardous Waste Management (EHWM), Bangkok 10330 (Thailand)

    2016-10-15

    In the present work, water-soluble cysteamine capped-CdS quantum dots (Cys-CdS QDs) modulated with Ag{sup +} were employed as fluorescence sensors for the determination of Hg{sup 2+} ion. The synthesized Cys-CdS QDs exhibit relatively weak fluorescence emission, however, the emission was enhanced exclusively in the presence of Ag{sup +} compared to other metal ions. Moreover, the fluorescence intensity of the Ag{sup +} modulated Cys-CdS QDs (Ag{sup +}@Cys-CdS QDs) was significantly quenched in the presence of trace amounts of Hg{sup 2+} due to high-affinity metallophilic interactions between Hg{sup 2+} and Ag{sup +}. Based on this specific interaction, good selectivity towards the detection of Hg{sup 2+} over other metal ions was achieved. To gain the best sensing performance, parameters affecting the Hg{sup 2+} detection sensitivity were studied and optimized in detail. Under the optimized conditions, the fluorescence intensity of Ag{sup +}@Cys-CdS QDs decreased linearly with Hg{sup 2+} concentration in the range of 0.1–3.5 μM, with a limit of detection of around 0.09 μM. The applicability of this sensor was demonstrated by the determination of Hg{sup 2+} in drinking water samples, corresponding well with results of cold-vapor atomic absorption spectrometry.

  5. 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

  6. Using ion-selective electrodes to study the drug release from porous cellulose matrices

    DEFF Research Database (Denmark)

    Vakili, Hossein; Genina, Natalja; Ehlers, Henrik

    2012-01-01

    -polymer solutions were prepared with the model drugs, using different blend ratios of ethylcellulose (EC) and hydroxypropyl cellulose (HPC). Two different solid dosage forms were used. Polymer films were produced by solvent casting method and drug containing porous cellulose samples were prepared by depositing...... the drug-polymer solutions onto filter paper substrates. The quality of the electrodes and the release profile of Pr+ and Ld+ were investigated with \\r\

  7. An evaluation of two types of nickel-titanium wires in terms of micromorphology and nickel ions' release following oral environment exposure.

    Science.gov (United States)

    Ghazal, Abdul Razzak A; Hajeer, Mohammad Y; Al-Sabbagh, Rabab; Alghoraibi, Ibrahim; Aldiry, Ahmad

    2015-01-01

    This study aimed to compare superelastic and heat-activated nickel-titanium orthodontic wires' surface morphology and potential release of nickel ions following exposure to oral environment conditions. Twenty-four 20-mm-length distal cuts of superelastic (NiTi Force I®) and 24 20-mm-length distal cuts of heat-activated (Therma-Ti Lite®) nickel-titanium wires (American Orthodontics, Sheboygan, WI, USA) were divided into two equal groups: 12 wire segments left unused and 12 segments passively exposed to oral environment for 1 month. Scanning electron microscopy and atomic force microscopy were used to analyze surface morphology of the wires which were then immersed in artificial saliva for 1 month to determine potential nickel ions' release by means of atomic absorption spectrophotometer. Heat-activated nickel-titanium (NiTi) wires were rougher than superelastic wires, and both types of wires released almost the same amount of Ni ions. After clinical exposure, more surface roughness was recorded for superelastic NiTi wires and heat-activated NiTi wires. However, retrieved superelastic NiTi wires released less Ni ions in artificial saliva after clinical exposure, and the same result was recorded regarding heat-activated wires. Both types of NiTi wires were obviously affected by oral environment conditions; their surface roughness significantly increased while the amount of the released Ni ions significantly declined.

  8. Comparison of nickel and chromium ions released from stainless steel and NiTi wires after immersion in Oral B®, Orthokin® and artificial saliva.

    Science.gov (United States)

    Jamilian, Abdolreza; Moghaddas, Omid; Toopchi, Shabnam; Perillo, Letizia

    2014-07-01

    Oral environment of the mouth is a suitable place for biodegradation of alloys used in orthodontic wires. The toxicity of these alloys namely nickel and chromium has concerned the researchers about the release of these ions from orthodontic wires and brackets. The aim of this study was to measure the levels of nickel and chromium ions released from 0.018" stainless steel (SS) and NiTi wires after immersion in three solutions. One hundred and forty-four round NiTi and 144 round SS archwires with the diameters of 0.018" were immersed in Oral B®, Orthokin® and artificial saliva. The amounts of nickel and chromium ions released were measured after 1, 6, 24 hours and 7 days. Two way repeated ANOVA showed that the amount of chromium and nickel significantly increased in all solutions during all time intervals (p nickel ions were released more in NiTi wire in all solutions compared with SS wire. The lowest increase rate was also seen in artificial saliva. There is general consensus in literature that even very little amounts of nickel and chromium are dangerous for human body specially when absorbed orally; therefore, knowing the precise amount of these ions released from different wires when immersed in different mouthwashes is of high priority.

  9. Composition-structure-property (Zn2+ and Ca2+ ion release) evaluation of Si-Na-Ca-Zn-Ce glasses: Potential components for nerve guidance conduits

    International Nuclear Information System (INIS)

    Zhang, X.F.; Kehoe, S.; Adhi, S.K.; Ajithkumar, T.G.; Moane, S.; O'Shea, H.; Boyd, D.

    2011-01-01

    Bioactive glasses have demonstrated tailored therapeutic ion release, primarily with respect to the augmentation of hard tissues. However, controlled degradation and release of therapeutic ions from biomaterials may also play an important role in soft tissue regeneration such as repair of peripheral nerve discontinuities. In this study, three silica based glasses (0.5SiO 2 -0.2CaO-0.13ZnO-XNa 2 O-(0.17-X) CeO 2 ) where, (0.04 29 Si isotope was probed for each glass using 29 Si MAS-NMR, whilst the thermal characteristics of each glass were examined using DTA. Following these analyses, ion release profiles for Ca 2+ and Zn 2+ were evaluated; an equivalent specific surface area of 1 m 2 of each glass powder was incubated (37 deg. C) in 10 ml of citric acid buffer and TRIS-HCI buffer solution (pH 3.0 and pH 7.4 respectively) for incubation periods of up to 30 days. The Zn 2+ concentration of each filtrate was analysed using flame Atomic Absorption Spectroscopy (Varian AA240FS Fast Sequential AAS) and the Ca 2+ concentration of each filtrate was determined using Inductively Coupled Plasma-Mass Spectrometer (Varian 820 ICP-MS). Results obtained from the 29 Si MAS-NMR spectra indicated Q 2 structures pervading the network. An analytical model was proposed to analyse the ion release profiles for each glass, and indicated heterogeneous dissolution of glass networks. The ion release data demonstrates that ion release in the range (19.26-3130 ppm) for Ca 2+ and in the range (5.97-4904 ppm) for Zn 2+ occurred. Release of such elements, at appropriate levels, from peripheral nerve guidance conduits may be advantageous with respect to the repair of peripheral nerve discontinuities.

  10. DNA derived fluorescent bio-dots for sensitive detection of mercury and silver ions in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Song, Ting [Laboratory of Environmental Science and Technology, Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi 830011 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Zhu, Xuefeng, E-mail: zhuxf@ms.xjb.ac.cn [Laboratory of Environmental Science and Technology, Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi 830011 (China); Zhou, Shenghai [Laboratory of Environmental Science and Technology, Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi 830011 (China); Yang, Guang [Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education and International Center for Dielectric Research, Xi’an Jiaotong University, Xi’an 710049 (China); Gan, Wei [Laboratory of Environmental Science and Technology, Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi 830011 (China); Yuan, Qunhui, E-mail: yuanqh@ms.xjb.ac.cn [Laboratory of Environmental Science and Technology, Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi 830011 (China)

    2015-08-30

    Highlights: • First application of a DNA derived fluorescent bio-dot for metal sensing. • Bio-dot was conveniently obtained via a mild thermal hydro-thermal synthesis. • Bio-dot was directly used for fluorescent sensing without further modification. • Bio-dot showed good fluorescent sensing property for Hg(II) and Ag(I). • Formation of T–Hg–T and C–Ag–C structures played key roles in sensing. - Abstract: Inspired by the high affinity between heavy metal ions and bio-molecules as well as the low toxicity of carbon-based quantum dots, we demonstrated the first application of a DNA derived carbonaceous quantum dots, namely bio-dots, in metal ion sensing. The present DNA-derived bio-dots contain graphitic carbon layers with 0.242 nm lattice fringes, exhibit excellent fluorescence property and can be obtained via a facile hydrothermal preparation procedure. Hg(II) and Ag(I) are prone to be captured by the bio-dots due to the existence of residual thymine (T) and cytosine (C) groups, resulting in a quenched fluorescence while other heavy metal ions would cause negligible changes on the fluorescent signals of the bio-dots. The bio-dots could be used as highly selective toxic-free biosensors, with two detecting linear ranges of 0–0.5 μM and 0.5–6 μM for Hg(II) and one linear range of 0–10 μM for Ag(I). The detection limits (at a signal-to-noise ratio of 3) were estimated to be 48 nM for Hg(II) and 0.31 μM for Ag(I), respectively. The detection of Hg(II) and Ag(I) could also be realized in the real water sample analyses, with satisfying recoveries ranging from 87% to 100%.

  11. DNA derived fluorescent bio-dots for sensitive detection of mercury and silver ions in aqueous solution

    International Nuclear Information System (INIS)

    Song, Ting; Zhu, Xuefeng; Zhou, Shenghai; Yang, Guang; Gan, Wei; Yuan, Qunhui

    2015-01-01

    Highlights: • First application of a DNA derived fluorescent bio-dot for metal sensing. • Bio-dot was conveniently obtained via a mild thermal hydro-thermal synthesis. • Bio-dot was directly used for fluorescent sensing without further modification. • Bio-dot showed good fluorescent sensing property for Hg(II) and Ag(I). • Formation of T–Hg–T and C–Ag–C structures played key roles in sensing. - Abstract: Inspired by the high affinity between heavy metal ions and bio-molecules as well as the low toxicity of carbon-based quantum dots, we demonstrated the first application of a DNA derived carbonaceous quantum dots, namely bio-dots, in metal ion sensing. The present DNA-derived bio-dots contain graphitic carbon layers with 0.242 nm lattice fringes, exhibit excellent fluorescence property and can be obtained via a facile hydrothermal preparation procedure. Hg(II) and Ag(I) are prone to be captured by the bio-dots due to the existence of residual thymine (T) and cytosine (C) groups, resulting in a quenched fluorescence while other heavy metal ions would cause negligible changes on the fluorescent signals of the bio-dots. The bio-dots could be used as highly selective toxic-free biosensors, with two detecting linear ranges of 0–0.5 μM and 0.5–6 μM for Hg(II) and one linear range of 0–10 μM for Ag(I). The detection limits (at a signal-to-noise ratio of 3) were estimated to be 48 nM for Hg(II) and 0.31 μM for Ag(I), respectively. The detection of Hg(II) and Ag(I) could also be realized in the real water sample analyses, with satisfying recoveries ranging from 87% to 100%

  12. Silver nanotoxicity using a light-emitting biosensor Pseudomonas putida isolated from a wastewater treatment plant.

    Science.gov (United States)

    Dams, R I; Biswas, A; Olesiejuk, A; Fernandes, T; Christofi, N

    2011-11-15

    The effect of silver ions, nano- and micro-particles on a luminescent biosensor bacterium Pseudomonas putida originally isolated from activated sludge was assessed. The bacterium carrying a stable chromosomal copy of the lux operon (luxCDABE) was able to detect toxicity of ionic and particulate silver over short term incubations ranging from 30 to 240 min. The IC(50) values obtained at different time intervals showed that highest toxicity (lowest IC(50)) was obtained after 90 min incubation for all toxicants and this is considered the optimum incubation for testing. The data show that ionic silver is the most toxic followed by nanosilver particles with microsilver particles being least toxic. Release of nanomaterials is likely to have an effect on the activated sludge process as indicated by the study using a common sludge bacterium involved in biodegradation of organic wastes. Copyright © 2011 Elsevier B.V. All rights reserved.

  13. Evaluation of the antibacterial efficacy of bamboo charcoal/silver biological protective material

    Energy Technology Data Exchange (ETDEWEB)

    Yang, F.-C. [Department of Applied Chemistry, Chung Cheng Institute of Technology, National Defense University (NDU), No. 190, Sanyuan 1st Street, Tahsi, Taoyuan, Taiwan (China); Wu, K.-H. [Department of Applied Chemistry, Chung Cheng Institute of Technology, National Defense University (NDU), No. 190, Sanyuan 1st Street, Tahsi, Taoyuan, Taiwan (China)], E-mail: khwu@ccit.edu.tw; Liu, M.-J. [Department of Applied Chemistry, Chung Cheng Institute of Technology, National Defense University (NDU), No. 190, Sanyuan 1st Street, Tahsi, Taoyuan, Taiwan (China); Lin, W.-P. [Department of Microbiology and Immunology, National Defense Medical Center, Taipei, Taiwan (China); Hu, M.-K. [School of Pharmacy, National Defense Medical Center, Taipei, Taiwan (China)

    2009-01-15

    Bamboo charcoal supporting silver (BC/Ag) was prepared by activation and chemical reduction. The BC/Ag composites were characterized by silver particle size and distribution, silver ion (Ag{sup +}) release and antibacterial properties. Scanning and transmission electron microscopy (SEM and TEM) showed that the Ag particles were distributed uniformly on the BC matrix. The Ag particle size was found to be less than 150 nm based on TEM. The Ag content and surface morphology of the BC/Ag composites depended on the initial concentration of AgNO{sub 3}, and the higher the Ag content, the smaller the specific surface area obtained on the BC. The antibacterial effects of the BC/Ag composite powders were assessed from the minimum inhibitory concentrations (MICs) and by the plate-counting method, and an excellent antibacterial performance was discovered.

  14. Pelepasan ion nikel dan kromium kawat Australia dan stainless steel dalam saliva buatan (The release of nickel and chromium ions from Australian wire and stainless steel in artificial saliva

    Directory of Open Access Journals (Sweden)

    Nolista Indah Rasyid

    2014-09-01

    Full Text Available Background: Fixed orthodontic treatment needs several types of wire to produce biomechanical force to move teeth. The use orthodontic wire within the mouth interacts with saliva, causing the release of nickel and chromium ions. Purpose: The study was aimed to examine the effect of immersion time in artificial saliva between special type of Australian wire and stainless steel on the release of nickel and chromium ions. Methods: Thirty special type Australian wires and 30 stainless steel wires were used in this study, each of which weighed 0.12 grams. The wires were immersed for 1, 7, 28, 35, 42, and 49 days in artificial saliva with a normal pH. The release of ions in saliva was examined using Atomic Absorption spectrophotometry. Results: The result indicated that the release of nickel ions on special type of Australian wire was larger than that on stainless steel wire (p<0.005, there were differences in the release of the amount of nickel ions on special type of Australia in different immersion time, and there was a correlation between the types of wire and immersion time. Nickel ions released from the special type of Australian wire detected on the 7th day of immersion and reached its peak on the 35th day, while from stainless steel wire were detected on the 49th day of immersion. The released of chromium ions from the special type of Australian wire and stainless steel wire were not detected until the 49th day of immersion. Conclusion: The release of nickel ions were highest on the 35th day of immersion in special type of Australian wire and they were detected on the 49th day in stainless steel wire. The release of chromium ions were not detected until 49th day of immersion in special type of Australian and stainless steel wire.Latar belakang: Perawatan ortodonti cekat memerlukan beberapa macam kawat untuk menghasilkan kekuatan biomekanika yang sesuai dalam menggerakkan gigi. Pemakaian kawat ortodonti di dalam mulut dapat bereaksi dengan

  15. Silver effect of Co–Ni composite material on energy storage and structural behavior for Li-ion batteries

    International Nuclear Information System (INIS)

    Gnanamuthu, RM.; Prasanna, K.; Subburaj, T.; Jo, Yong Nam; Lee, Chang Woo

    2013-01-01

    Ag powder has been comparatively applied to the Co–Ni materials preparing by mixing method and the prepared electrodes were used as negative electrodes for Li-ion batteries applications. The prepared Co–Ni and Ag–Co–Ni with 10 wt.% of Ag composite electrodes are characterized by XRD, FE-SEM with EDX, impedance and electrochemical charge-discharge studies. These electrochemical studies are demonstrated at current rates of 0.1 C and 0.5 C between 0.01 and 2.0 V vs. Li/Li + . The porous Co–Ni and Ag–Co–Ni composite materials are electrochemically tested in lithium half cells. The porous Ag–Co–Ni composite material demonstrates that the initial and end of discharge capacity up to 20th cycles is, respectively, 860 and 715 mAh g −1 at 0.1 C rate maintaining at approximately 83%. The porous Ag–Co–Ni composite electrode may be a good candidate for high power lithium-ion batteries.

  16. In-situ complex with by-product HCl and release chloride ions to dissolve aramid.

    Science.gov (United States)

    Dai, Yu; Cheng, Zheng; Yuan, Yihao; Meng, Chenbo; Qin, Jiaqiang; Liu, Xiangyang

    2018-06-20

    Because of the strong hydrogen-bond interaction among macromolecular chains, addition of chloride salts is generally needed to offer Cl- ions for dissolution of aromatic polyamides. In this paper, poly-(benzimidazole-terephthalamide) which complexed with by-product HCl during polymerization (PABI-HCl) was prepared and imidazole compound as cosolvent was added into dimethylacetamide (DMAc) to dissolve PABI-HCl. Due to stronger affinity to protons, imidazole compound could in-situ complex with HCl of PABI-HCl and form imidazolium hydrochloride. Then imidazolium hydrochloride would ionize and produce much free Cl- ions which acted as stronger hydrogen-bond acceptor to disrupt interaction among macromolecular chains. As a result, solubility of PABI-HCl in DMAc was improved significantly in existence of small amount of imidazole compound. Moreover, DMAc-imidazole mixture was utlized for synthesis of different kinds of aramids and no precipitation was observed with progress of the reaction. So the mixture was suitable to be utlized as solvent for polymerization of aramid. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Potentiometer determination of sulfur using silver/sulfur ion selective electrodes; Determinacion potenciometrica de sulfuros mediante electrodo-ion-selectivo de plata/sulfuro

    Energy Technology Data Exchange (ETDEWEB)

    Salamanca Grosso, G. [Departamento de Quimica, Instituto de Ciencias, Universidad de Tolima, Tolima (Colombia)

    1996-06-01

    New devices in analytical chemistry, has been emerged, and new procedures take great interest. The use of electrodes ion selective are very important in water and wastewater control of Ag+/S= electrodes for control process in wastewater from UASE plan pilot, before check their potentiometric performance so: 28.6+- 0.4 mV/decade, optimal time 20 seconds, and pH>10, detection limit 1.8 x 10``-6. The study was made in comparative way with yodometrical method: we check quantification by addition, subtraction an GRANT`s titrimetric. (Author) 10 refs.

  18. Unbiased simulations reveal the inward-facing conformation of the human serotonin transporter and Na+ ion release

    DEFF Research Database (Denmark)

    Koldsø, Heidi; Noer, Pernille Rimmer; Grouleff, Julie

    2011-01-01

    transporter has resulted in homology models of the monoamine transporters. Here we present extended molecular dynamics simulations of an experimentally supported homology model of hSERT with and without the natural substrate yielding a total of more than 1.5 µs of simulation of the protein dimer....... The simulations reveal a transition of hSERT from an outward-facing occluded conformation to an inward-facing conformation in a one-substrate-bound state. Simulations with a second substrate in the proposed symport effector site did not lead to conformational changes associated with translocation. The central...... substrate binding site becomes fully exposed to the cytoplasm leaving both the Na+-ion in the Na2-site and the substrate in direct contact with the cytoplasm through water interactions. The simulations reveal how sodium is released and show indications of early events of substrate transport. The notion...

  19. Measurement of release of endogenous GABA and catabolites of [3H]GABA from synaptosomal preparations using ion-exchange chromatography

    International Nuclear Information System (INIS)

    Grove, J.; Gardner, C.R.; Richards, M.H.

    1982-01-01

    Picomole quantities of endogenous GABA in acidified superfusates of synaptosomal preparations have been measured using micro-bore ion-exchange chromatography and post-column formation of the fluorescent iso-indole derivative. Using this technique superfusates have been analyzed directly, without further manipulations, to investigate the release of endogenous GABA. Spontaneous release of GABA was 2-5 pmol/200 microliters superfusate increasing to 20 pmol/200 microliters with potassium stimulation. When gamma-vinyl GABA (RMI 71754), an inhibitor of GABA-T was injected into rats (750 mg/kg) and synaptosomes prepared the potassium-evoked release of GABA was increased 3-fold compared to controls. Chromatographic separations and measurement of release of endogenous and radiolabeled GABA allowed the real specific activity of released GABA to be calculated. Only when 500 microM amino-oxyacetic acid was added during isolation of synaptosomes was the specific activity of released GABA the same as the initial specific activity

  20. Silver-nickel oxide core-shell nanoflower arrays as high-performance anode for lithium-ion batteries

    Science.gov (United States)

    Zhao, Wenjia; Du, Ning; Zhang, Hui; Yang, Deren

    2015-07-01

    We demonstrate the synthesis of Ag-NiO core-shell nanoflower arrays via a one-step solution-immersion process and subsequent RF-sputtering method. The aligned Ag nanoflower arrays on copper substrate are prepared by a facile displacement reaction in absence of any surfactant at a mild temperature. When used as anode materials for lithium-ion batteries, the Ag-NiO core-shell nanoflower arrays show better cycling performance and higher capacity than the planar NiO electrodes. The improved performance should be attributed to the core-shell structures that can enhance the conductivity and accommodate the volume change during the charge-discharge process.

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

    Energy Technology Data Exchange (ETDEWEB)

    Ferraris, M.; Perero, S. [Politecnico di Torino, Department of Applied Science and Technology, Torino, C.so Duca degli Abruzzi 24, I-10129 (Italy); Ferraris, S., E-mail: sara.ferraris@polito.it [Politecnico di Torino, Department of Applied Science and Technology, Torino, C.so Duca degli Abruzzi 24, I-10129 (Italy); Miola, M.; Vernè, E. [Politecnico di Torino, Department of Applied Science and Technology, Torino, C.so Duca degli Abruzzi 24, I-10129 (Italy); Skoglund, S. [KTH Royal Institute of Technology, Div. Surface and Corrosion Science, Dr. Kristinas v. 51, SE-100 44 (Sweden); Blomberg, E. [KTH Royal Institute of Technology, Div. Surface and Corrosion Science, Dr. Kristinas v. 51, SE-100 44 (Sweden); SP Technical Research Institute of Sweden, Chemistry, Materials and Surfaces, P.O. Box 5607, SE-114 86 Stockholm (Sweden); Odnevall Wallinder, I. [KTH Royal Institute of Technology, Div. Surface and Corrosion Science, Dr. Kristinas v. 51, SE-100 44 (Sweden)

    2017-02-28

    Highlights: • A silver nanocluster-silica composite coating sputter-deposited onto stainless steel. • Good adhesion and resistance upon cleaning with NaOH, H{sub 2}SO{sub 4} and detergents. • Low release of silver ions and no release as silver nanoparticles. • Good antibacterial activity against S. aureus even after heating to 450 °C. • Good antibacterial activity shown during cheese production. - Abstract: 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

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

    International Nuclear Information System (INIS)

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

    2017-01-01

    Highlights: • A silver nanocluster-silica composite coating sputter-deposited onto stainless steel. • Good adhesion and resistance upon cleaning with NaOH, H_2SO_4 and detergents. • Low release of silver ions and no release as silver nanoparticles. • Good antibacterial activity against S. aureus even after heating to 450 °C. • Good antibacterial activity shown during cheese production. - Abstract: 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

  3. Investigation on the ion pair amphiphiles and their in vitro release of amantadine drug based on PLGA–PEG–PLGA gel

    International Nuclear Information System (INIS)

    Yang, Xiaoxia; Ji, Xiaoqing; Shi, Chunhuan; Liu, Jing; Wang, Haiyang; Luan, Yuxia

    2014-01-01

    The amantadine drug and oleic acid surfactant are used to form amantadine-based ion pair amphiphiles based on proton transfer reaction between the drug and the surfactant molecules. The ion pair amphiphiles are characterized by 1 H-nuclear magnetic resonance, Fourier transform infrared spectroscopy, and X-ray diffraction. Self-assembly properties of amantadine-based ion pair amphiphiles are studied by surface tension determination, transmission electron microscopy, zeta potential, and dynamic light scattering. The aggregation behavior studies indicate that the as-prepared ion pair amphiphiles can self-assemble into vesicles with the size of 200–300 nm in aqueous solution. The drug release results show that the amantadine release rate could be well controlled by incorporating the amantadine-based ion pair vesicles in poly (lactic-co-glycolic acid)-poly (ethylene glycol)-poly (lactic-co-glycolic acid) (PLGA–PEG–PLGA) copolymer hydrogel. The drug release from the AT–OA vesicle-loaded PLGA–PEG–PLGA hydrogel is significantly inhibited in comparison with the AT-loaded PLGA–PEG–PLGA hydrogel. The present work thus demonstrates that the vesicle-loaded hydrogel is a good candidate for the drug delivery system with long-term controlled drug release behavior

  4. Unbiased simulations reveal the inward-facing conformation of the human serotonin transporter and Na(+ ion release.

    Directory of Open Access Journals (Sweden)

    Heidi Koldsø

    2011-10-01

    Full Text Available Monoamine transporters are responsible for termination of synaptic signaling and are involved in depression, control of appetite, and anxiety amongst other neurological processes. Despite extensive efforts, the structures of the monoamine transporters and the transport mechanism of ions and substrates are still largely unknown. Structural knowledge of the human serotonin transporter (hSERT is much awaited for understanding the mechanistic details of substrate translocation and binding of antidepressants and drugs of abuse. The publication of the crystal structure of the homologous leucine transporter has resulted in homology models of the monoamine transporters. Here we present extended molecular dynamics simulations of an experimentally supported homology model of hSERT with and without the natural substrate yielding a total of more than 1.5 µs of simulation of the protein dimer. The simulations reveal a transition of hSERT from an outward-facing occluded conformation to an inward-facing conformation in a one-substrate-bound state. Simulations with a second substrate in the proposed symport effector site did not lead to conformational changes associated with translocation. The central substrate binding site becomes fully exposed to the cytoplasm leaving both the Na(+-ion in the Na2-site and the substrate in direct contact with the cytoplasm through water interactions. The simulations reveal how sodium is released and show indications of early events of substrate transport. The notion that ion dissociation from the Na2-site drives translocation is supported by experimental studies of a Na2-site mutant. Transmembrane helices (TMs 1 and 6 are identified as the helices involved in the largest movements during transport.

  5. Silver Biocide Analysis & Control Device, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Rapid, accurate measurement and process control of silver ion biocide concentrations in future space missions is needed. The purpose of the Phase II program is to...

  6. One-pot silver nanoring synthesis.

    OpenAIRE

    Drogat , Nicolas; Granet , Robert; Sol , Vincent; Krausz , Pierre

    2009-01-01

    Abstract Silver colloidal nanorings have been synthesized by reducing silver ions with NaBH4 in trisodium citrate buffers. pH increase, by addition of NaOH, was used to speed up reduction reaction. The UV–vis absorption spectra of resulting silver nanorings showed two peaks accounting for transverse and longitudinal surface plasmon resonance, at ≈400 nm, and between 600 and 700 nm, respectively. The shapes of these silver nanoparticles (nanorings) depended on AgNO3/NaBH4 ratio, pH...

  7. Preparation and SERS performance of Au NP/paper strips based on inkjet printing and seed mediated growth: The effect of silver ions

    Science.gov (United States)

    Weng, Guojun; Yang, Yue; Zhao, Jing; Zhu, Jian; Li, Jianjun; Zhao, Junwu

    2018-04-01

    Surface-enhanced Raman scattering (SERS) has been widely used in biomedical sensing with the advantages of high sensitivity and label-free. However, the fabrication of SERS substrates with good Raman activity, reproducibility, and low cost is still under development in practical applications. This paper presents a practicable method for fabricating Au NP/paper strips by using inkjet printing and seed mediated growth. Small gold seed synthesized by borohydride reduction was used as ink and printed on the filter paper. The printed gold seed grew in situ in the growth solution and formed the gold nanoparticle (Au NP)/paper strips. The fabricated paper strip was characterized by diffuse reflectance spectroscopy and scanning electron microscopy (SEM). The diffuse reflectance spectra indicated that the Au NP/paper strips had two local surface plasmon resonance (LSPR) peaks: the short one at around 540 nm and the long one located in the range of 640-840 nm. And the long LSPR peak firstly shifted to red then to blue with the increased concentrations of silver ions in growth solution. From the SEM images, the shape of grown Au NPs was diverse, including sphere, rod, ellipsoid, dimer, trimer, and big aggregates. We thought the short peak came from the LSPR of nanospheres and the transvers LSPR of rod and ellipsoid like particles, while the long peak mainly came from the plasmonic coupling of dimer along the inter-particle axis. The obtained Au NP/paper strip with the long peak located around 650 nm had the highest SERS activity, which could be attributed to the plasmon resonance induced local field enhancement and nanogap effect. Also, the SERS performance results indicated the printed SERS strips exhibited satisfied uniformity and stability, demonstrating the potential of Au NP/paper strip in real-world applications.

  8. Determination of mercury (II) ions based on silver-nanoparticles-assisted growth of gold nanostructures: UV-Vis and surface enhanced Raman scattering approaches

    Science.gov (United States)

    Chen, Jun-Liang; Yang, Pei-Chia; Wu, Tsunghsueh; Lin, Yang-Wei

    2018-06-01

    Innovative dual detection methods for mercury(II) ions (Hg(II)) have been developed based on the formation of gold nanostructures (AuNSs) following the addition of mercury-containing solution to a mixture containing an optimized amount of Au(III), H2O2, HCl, and silver nanoparticles (AgNPs). In the absence of Hg(II), the addition of Au(III), H2O2, and HCl to the AgNP solution changes the solution's color from yellow to red, and the absorption peak shifts from 400 to 526 nm, indicating the dissolution of AgNPs and the formation of gold nanoparticles (AuNPs). Because of the spontaneous redox reaction of Hg(II) toward AgNPs, the change in the amount of remaining AgNP seed facilitates the generation of irregular AuNSs, resulting in changes in absorption intensity and shifting the peak within the range from 526 to 562 nm depending on the concentration of Hg(II). Under optimal conditions, the limit of detection (LOD) for Hg(II) at a signal-to-noise ratio (S/N) of 3 was 0.3 μM. We further observed that AgNP-assisted catalytic formation of Au nanomaterials deposited on a surface enhanced Raman scattering active substrate significantly reduced the Raman signal of 4-mercaptobenzoic acid, dependent on the Hg(II) concentration. A linear relationship was observed in the range 0.1 nM-100 μM with a LOD of 0.05 nM (S/N 3.0). As a simple, accurate and precise method, this SERS-based assay has demonstrated its success in determining levels of Hg(II) in real water samples.

  9. Trace metal ions release from fixed orthodontic appliances and DNA damage in oral mucosa cells by in vivo studies: A literature review.

    Science.gov (United States)

    Downarowicz, Patrycja; Mikulewicz, Marcin

    2017-10-01

    An overview of professional literature referring to the release of metal ions from fixed orthodontic appliances and their influence on oral mucosa in conditions of in vivo are presented, along with a detailed analysis of the exposure of the cells of cheek mucosa epithelium to metal ions. Electronic databases (PubMed, Elsevier, Ebsco) were searched with no language restrictions. The relevant orthodontic journals and reference lists were checked for all eligible studies. A total of 38 scientific articles were retrieved in the initial search. However, only 7 articles met the inclusion criteria. Statistically significant differences in the levels of the amount of nickel ions, cobalt ions and chromium ions were observed in cells of cheek mucosa. The most biocompatible material used in the production of fixed orthodontic appliances is titanium, and the least biocompatible material is steel, which releases the largest amount of nickel and chromium. Metal ions are released from fixed orthodontic appliances only in the first phase of treatment. It is recommended to conduct further, long-term research on a larger number of patients to define the influence of using fixed orthodontic appliances and biological effect they might have on tissues.

  10. Efficacy of silver/hydrophilic poly(p-xylylene) on preventing bacterial growth and biofilm formation in urinary catheters.

    Science.gov (United States)

    Heidari Zare, Hamideh; Juhart, Viktorija; Vass, Attila; Franz, Gerhard; Jocham, Dieter

    2017-01-18

    Catheter associated urinary tract infections (CAUTI), caused by several strains of bacteria, are a common complication for catheterized patients. This may eventually lead to a blockage of the catheter due to the formation of a crystalline or amorphous biofilm. Inhibiting bacteria should result in a longer application time free of complaints. This issue has been investigated using an innovative type of silver-coated catheter with a semipermeable cap layer to prevent CAUTI. In this work, two different types of silver catheters were investigated, both of which were capped with poly(p-xylylene) (PPX-N) and exhibited different surface properties that completely changed their wetting conduct with water. The contact angle of conventionally deposited PPX-N is approximately 80°. After O 2 plasma treatment, the contact angle drops to approximately 30°. These two systems, Ag/PPX-N and Ag/PPX-N-O 2 , were tested in synthetic urine at a body temperature of 37 °C. First, the optical density and the inhibition zones of both bacteria strains (Escherichia coli and Staphylococcus cohnii) were examined to confirm the antibacterial effect of these silver-coated catheters. Afterward, the efficacy of silver catheters with different treatments of biofilm formed by E. coli and S. cohnii were tested with crystal violet staining assays. To estimate the life cycles of silver/PPX-catheters, the eluted amount of silver was assessed at several time intervals by anodic stripping voltammetry. The silver catheter with hydrophilic PPX-N coating limited bacterial growth in synthetic urine and prevented biofilm formation. The authors attribute the enhanced bacteriostatic effect to increased silver ion release detected under these conditions. With this extensive preparatory analytic work, the authors studied the ability of the two different cap layers (without silver), PPX-N and oxygen plasma treated PPX-N, to control the growth of a crystalline biofilm by measuring the concentrations of the Ca 2

  11. New, rapid method to measure dissolved silver concentration in silver nanoparticle suspensions by aggregation combined with centrifugation

    International Nuclear Information System (INIS)

    Dong, Feng; Valsami-Jones, Eugenia; Kreft, Jan-Ulrich

    2016-01-01

    It is unclear whether the antimicrobial activities of silver nanoparticles (AgNPs) are exclusively mediated by the release of silver ions (Ag"+) or, instead, are due to combined nanoparticle and silver ion effects. Therefore, it is essential to quantify dissolved Ag in nanosilver suspensions for investigations of nanoparticle toxicity. We developed a method to measure dissolved Ag in Ag"+/AgNPs mixtures by combining aggregation of AgNPs with centrifugation. We also describe the reproducible synthesis of stable, uncoated AgNPs. Uncoated AgNPs were quickly aggregated by 2 mM Ca"2"+, forming large clusters that could be sedimented in a low-speed centrifuge. At 20,100g, the sedimentation time of AgNPs was markedly reduced to 30 min due to Ca"2"+-mediated aggregation, confirmed by the measurements of Ag content in supernatants with graphite furnace atomic absorption spectrometry. No AgNPs were detected in the supernatant by UV–Vis absorption spectra after centrifuging the aggregates. Our approach provides a convenient and inexpensive way to separate dissolved Ag from AgNPs, avoiding long ultracentrifugation times or Ag"+ adsorption to ultrafiltration membranes.

  12. New, rapid method to measure dissolved silver concentration in silver nanoparticle suspensions by aggregation combined with centrifugation

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Feng, E-mail: fengdongub@gmail.com [University of Birmingham, Institute of Microbiology and Infection, School of Biosciences (United Kingdom); Valsami-Jones, Eugenia [University of Birmingham, School of Geography, Earth and Environmental Sciences (United Kingdom); Kreft, Jan-Ulrich [University of Birmingham, Institute of Microbiology and Infection, School of Biosciences (United Kingdom)

    2016-09-15

    It is unclear whether the antimicrobial activities of silver nanoparticles (AgNPs) are exclusively mediated by the release of silver ions (Ag{sup +}) or, instead, are due to combined nanoparticle and silver ion effects. Therefore, it is essential to quantify dissolved Ag in nanosilver suspensions for investigations of nanoparticle toxicity. We developed a method to measure dissolved Ag in Ag{sup +}/AgNPs mixtures by combining aggregation of AgNPs with centrifugation. We also describe the reproducible synthesis of stable, uncoated AgNPs. Uncoated AgNPs were quickly aggregated by 2 mM Ca{sup 2+}, forming large clusters that could be sedimented in a low-speed centrifuge. At 20,100g, the sedimentation time of AgNPs was markedly reduced to 30 min due to Ca{sup 2+}-mediated aggregation, confirmed by the measurements of Ag content in supernatants with graphite furnace atomic absorption spectrometry. No AgNPs were detected in the supernatant by UV–Vis absorption spectra after centrifuging the aggregates. Our approach provides a convenient and inexpensive way to separate dissolved Ag from AgNPs, avoiding long ultracentrifugation times or Ag{sup +} adsorption to ultrafiltration membranes.

  13. The potential/pH diagram of silver in aqueous ammonium salt solution

    NARCIS (Netherlands)

    Sluyters, J.H.; Wijnen, M.D.; Hul, H.J. van den

    1961-01-01

    The potential/pH diagram of silver in aqueous ammonium salt solution at 25°C has been calculated and verified experimentally. Calculations were carried out on the basis of the standard potential of the silver/silver-ion couple, the dissociation constants of the silver mono- and di-ammonia

  14. Uptake of free and complexed silver ions by different strains of Rhodotorula mucilaginosa Acúmulo de íons de prata livres e complexados por diferentes linhagens de Rhodotorula mucilaginosa

    Directory of Open Access Journals (Sweden)

    Newton C.M. Gomes

    2002-01-01

    Full Text Available Five strains of Rhodotorula mucilaginosa were tested for the ability to accumulate free and complexed silver ions by metabolism-dependent and -independent processes. The ability to take up Ag+ was observed in both live and dead biomass, whereas silver dicyanide [Ag (CN2-] uptake was strictly glucose dependent. In contrast to Ag (CN2-, glucose addition inhibited by 16 to 25% the Ag+ uptake rate of living UFMG - Y02, Y27, and Y35 cells, while strains CBS 316 and UFMG-Y01 showed an improved uptake rate of about 115% and 13%, respectively. The Langmuir sorption model was used to evaluate the silver sorption capability of the R. mucilaginosa strains. The calculated q max value suggested that R. mucilaginosa strains UFMG-Y27 had the highest loading capacity. The type strain CBS 316 had the lowest q max but showed the highest affinity for silver ions. The results provided by the Fourier Transform Infra Red analysis (FTIR suggest that C=O groups represent the main reactive site for silver uptake by the strain UFMG-Y27.Quatro linhagens de Rhodotorula mucilaginosa e uma linhagem padrão dessa mesma espécie foram investigadas quanto a habilidade de acumular íons de prata livres (Ag+ e complexados [Ag (CN2-], através de processos dependentes e independentes do metabolismo. A habilidade de acumular Ag+ foi observada em ambas as células, vivas e mortas. Contudo, o acúmulo de Ag (CN2- foi um processo estritamente dependente de energia. Durante os estudos que avaliaram a dependência de uma fonte energética para o acumulo de íons de prata livres (Ag+ foi observado que a adição de glicose resultou na diminuição do acúmulo de Ag+ por três linhagens (UFMG -- Y02, 27 and 35. Ao passo que as linhagens CBS 316 e UFMG -- Y01 apresentaram aumento do acúmulo desse metal. A analise dos resultados de biossorção através do modelo de Langmuir, sugerem que a linhagem UFMG -- Y27 possui a maior capacidade de acúmulo de prata (carga. Enquanto que a linhagem

  15. Multivalent calix[4]arene-based fluorescent sensor for detecting silver ions in aqueous media and physiological environment.

    Science.gov (United States)

    Lotfi, Behzad; Tarlani, Aliakbar; Akbari-Moghaddam, Peyman; Mirza-Aghayan, Maryam; Peyghan, Ali Ahmadi; Muzart, Jacques; Zadmard, Reza

    2017-04-15

    A new derivative of dipodal 1,3-calix[4]arene-based chemosensor (R), which was containing several binding sites have been synthesized and characterized by NMR, IR and LC-MS spectroscopic methods. The selectivity of Rhas been investigated in aqueous methanol, resulting in fluorescence shift and selective recognition of Ag + among 20 various alkali, alkaline earth and transition metal ions. Microstructural features of R and its complex with Ag + have been investigated by Atomic Force Microscopy (AFM). AFM images can clearly differentiate R from its complex of Ag + . Moreover; the complicated binding mode of metal-ligand complex has been explored by UV-Vis, LC-MS, FIR, Fluorescence titration, Job's plot method and theoretical approaches. Density functional theory (DFT) method at B3LYP/LANL2DZ level of theory was employed for computational studies. Theoretical calculations revealed that selectivity and specificity of R toward Ag + could be attributed to structural conformation of 1,3-alternate-calix[4]arene scaffold and molecular electrostatic potential of its surface. Furthermore; the competitive experiments were carried out to test sensor's ability for practical uses. Finally, the efficiency of R in matrix of physiological cations was examined and showed gradual emission enhancement which makes R an ideal candidate for monitoring of Ag + in physiological environment. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Analysis of wax esters by silver-ion high-performance liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Vrkoslav, Vladimír; Urbanová, Klára; Háková, Matina; Cvačka, Josef

    2013-08-09

    Wax esters (WEs), esters of long-chain fatty acids and long-chain alcohols, were analysed by Ag-HPLC/APCI-MS/MS. Two ChromSpher Lipids columns connected in series (a total length of 50cm) and hexane-2-propanol-acetonitrile mobile phases were used to achieve good separation of the molecular species. The chromatographic behaviour of WEs was studied under optimised conditions: retention increased with the number of double bonds and with the temperature (15-35°C); retention times were affected by the double-bond position, trans isomers eluted earlier than cis isomers, and the WEs were partially separated depending on the aliphatic-chain length. The WEs provided simple APCI spectra with [M+H](+) ions, the MS/MS spectra showed fragments, which allowed their identification. The method was applied for an analysis of the WE mixtures from jojoba oil and human hair and the results were compared with analogous data from an optimised RP-HPLC system. Copyright © 2013 Elsevier B.V. All rights reserved.

  17. Extraction of silver by gels of sodium poly-acrylic-polyacrylate acid. Application: elimination of chloride anions; Extraction de l'argent par des gels d'acide polyacrylique-polyacrylate de sodium. Application a l'elimination des ions chlorures

    Energy Technology Data Exchange (ETDEWEB)

    Rifi, E.H. [Universite Ibn-Tofail, Lab. de Synthese Organique et Pocedes d' Extraction, Faculte des Sciences, Kenitra (Morocco); Lakkis, D.; Leroy, J.F.M. [Universite Louis Pasteur, Lab. de Chimie Analytique et Minerale, Ecole Europeenne de Chimie, Polymeres et Materiaux, 67 - Strasbourg (France)

    2005-05-01

    The extraction of silver from diluted aqueous solutions by gels of sodium poly-acrylic-polyacrylate acid was studied. The study of pH variations shows that the extraction is done by cation-cation exchange process. The highest loading of the gel by silver is obtained at R(moles of Ag{sup +} fixed by the gel/moles of -COO(H, Na))=0.75. The silver gel loaded allows the recovery of ions chlorides from the aqueous solutions. (authors)

  18. Chitosan–silver oxide nanocomposite film: Preparation and ...

    Indian Academy of Sciences (India)

    (Yoshida et al 1999; Herrera et al 2001), ion exchange fibres. (Nonaka et al ... In this communication, we report the synthesis of .... The SEM pictures of chitosan, silver oxide and .... system for silver ions or as a contact-active material (Chan.

  19. Impact of silver ions on features of BCG′s adhesion on the silicone tube surface%银离子对卡介苗菌株黏附硅胶管表面特性的影响

    Institute of Scientific and Technical Information of China (English)

    赵永彬; 王永; 赵亚群

    2016-01-01

    Objective To explore the impact of silver ions on the adhesion ability of Bacillus Calmette-Gueri vaccine on silicone tube surface. Methods Common and silver plated silicone tubes were cultured in BCG bacterial liquid for 30 days. A gas-bacilli was taken once every 3 days to measure OD value of microbial. The growth curve of BCG vaccine was made. The corresponding silicone tubes in divided different generations was removed and eluted based on the division cycle of BCG vaccine. The samples were inoculated on the solid medium for observing the colony growth amount, and adhesion curve was drawn. The silicone tube colony line was observed under the electron microscope at day 30. Results OD value and bacterial plaque number were less in silver silicone tube group than in common silicone tube group, with statistical significances (P < 0.05). Electron microscopy also showed that BCG adhesion on silver silicone tube group was relatively less than that on common silicone tube group. Conclusion Silver ions can reduce the adhesion of BCG vaccine on silicone tube surface and inhibit the growth of BCG vaccine.%目的:研究银离子对卡介苗黏附硅胶管表面能力的影响。方法:分别将普通硅胶管与镀银硅胶管在卡介苗菌液中培养30 d,每3 d测定菌液OD值,绘制生长曲线;依据卡介苗分裂周期,在分裂不同代数时取出硅胶管并洗脱,于固体培养基上接种观察和记录查看菌落数量,绘制黏附曲线;电镜观察培养30 d的硅胶管细菌黏附情况。结果:镀银硅胶管组每次采样测定的OD值和菌斑个数均少于普通硅胶管组,差异具有统计学意义(P <0.05)。电镜观察镀银硅胶管组卡介苗黏附数量也少于普通硅胶管组。结论:银离子可降低卡介苗菌株在硅胶管表面的黏附并且可抑制卡介苗的生长。

  20. Room temperature synthesis of silver nanowires from tabular silver bromide crystals in the presence of gelatin

    Science.gov (United States)

    Liu, Suwen; Wehmschulte, Rudolf J.; Lian, Guoda; Burba, Christopher M.

    2006-03-01

    Long silver nanowires were synthesized at room temperature by a simple and fast process derived from the development of photographic films. A film consisting of an emulsion of tabular silver bromide grains in gelatin was treated with a photographic developer (4-(methylamino)phenol sulfate (metol), citric acid) in the presence of additional aqueous silver nitrate. The silver nanowires have lengths of more than 50 μm, some even more than 100 μm, and average diameters of about 80 nm. Approximately, 70% of the metallic silver formed in the reduction consists of silver nanowires. Selected area electron diffraction (SAED) results indicate that the silver nanowires grow along the [111] direction. It was found that the presence of gelatin, tabular silver bromide crystals and silver ions in solution are essential for the formation of the silver nanowires. The nanowires appear to originate from the edges of the silver bromide crystals. They were characterized by transmission electron microscopy (TEM), SAED, scanning electron microscopy (SEM), and powder X-ray diffraction (XRD).

  1. Room temperature synthesis of silver nanowires from tabular silver bromide crystals in the presence of gelatin

    International Nuclear Information System (INIS)

    Liu Suwen; Wehmschulte, Rudolf J.; Lian Guoda; Burba, Christopher M.

    2006-01-01

    Long silver nanowires were synthesized at room temperature by a simple and fast process derived from the development of photographic films. A film consisting of an emulsion of tabular silver bromide grains in gelatin was treated with a photographic developer (4-(methylamino)phenol sulfate (metol), citric acid) in the presence of additional aqueous silver nitrate. The silver nanowires have lengths of more than 50 μm, some even more than 100 μm, and average diameters of about 80 nm. Approximately, 70% of the metallic silver formed in the reduction consists of silver nanowires. Selected area electron diffraction (SAED) results indicate that the silver nanowires grow along the [111] direction. It was found that the presence of gelatin, tabular silver bromide crystals and silver ions in solution are essential for the formation of the silver nanowires. The nanowires appear to originate from the edges of the silver bromide crystals. They were characterized by transmission electron microscopy (TEM), SAED, scanning electron microscopy (SEM), and powder X-ray diffraction (XRD)

  2. Silver linings.

    Science.gov (United States)

    Bultas, Margaret W; Pohlman, Shawn

    2014-01-01

    The purpose of this interpretive phenomenological study was to gain a better understanding of the experiences of 11 mothers of preschool children with autism spectrum disorder (ASD). Mothers were interviewed three times over a 6 week period. Interviews were analyzed using interpretive methods. This manuscript highlights one particular theme-a positive perspective mothers described as the "silver lining." This "silver lining" represents optimism despite the adversities associated with parenting a child with ASD. A deeper understanding of this side of mothering children with ASD may help health care providers improve rapport, communication, and result in more authentic family centered care. Copyright © 2014 Elsevier Inc. All rights reserved.

  3. Can a novel silver nano coating reduce infections and maintain cell viability in vitro?

    Science.gov (United States)

    Qureshi, Ammar T; Landry, Jace P; Dasa, Vinod; Janes, Marlene; Hayes, Daniel J

    2014-03-01

    Herein we report a facile layer-by-layer method for creating an antimicrobial coating composed of silver nanoparticles on medical grade titanium test discs. Nanoscale silver nanoparticle layers are attached to the titanium orthopedic implant material via aminopropyltriethoxy silane crosslinker that reacts with neighboring silane moieties to create an interconnected network. A monolayer of silane, followed by a monolayer of silver nanoparticles would form one self-assembled layer and this process can be repeated serially, resulting in increased silver nanoparticles deposition. The release rate of silver ion increases predictably with increasing numbers of layers and at appropriate thicknesses these coatings demonstrate 3-4 log reduction of viable Escherichia coli and Staphylococcus aureus bacteria. Increasing the thickness of the coatings resulted in reduced bacterial colonization as determined by fluorescent staining and image analysis. Interestingly, the cytotoxicity of murine 3T3 cells as quantified by fluorescent staining and flow cytometry, was minimal and did not vary significantly with the coating thickness. Additionally, these coatings are mechanically stable and resist delamination by orthogonal stress test. This simple layer-by-layer coating technique may provide a cost-effective and biocompatible method for reducing microbial colonization of implantable orthopedic devices.

  4. Hydrophobic ion pairing of a minocycline/Ca(2+)/AOT complex for preparation of drug-loaded PLGA nanoparticles with improved sustained release.

    Science.gov (United States)

    Holmkvist, Alexander Dontsios; Friberg, Annika; Nilsson, Ulf J; Schouenborg, Jens

    2016-02-29

    Polymeric nanoparticles is an established and efficient means to achieve controlled release of drugs. Incorporation of minocycline, an antibiotic with anti-inflammatory and neuroprotective properties, into biodegradable nanoparticles may therefore provide an efficient means to combat foreign body reactions to implanted electrodes in the brain. However, minocycline is commonly associated with poor encapsulation efficiencies and/or fast release rates due to its high solubility in water. Moreover, minocycline is unstable under conditions of low and high pH, heat and exposure to light, which exacerbate the challenges of encapsulation. In this work drug loaded PLGA nanoparticles were prepared by a modified emulsification-solvent-diffusion technique and characterized for size, drug encapsulation and in vitro drug release. A novel hydrophobic ion pair complex of minocycline, Ca(2+) ions and the anionic surfactant AOT was developed to protect minocycline from degradation and prolong its release. The optimized formulation resulted in particle sizes around 220 nm with an entrapment efficiency of 43% and showed drug release over 30 days in artificial cerebrospinal fluid. The present results constitute a substantial increase in release time compared to what has hitherto been achieved for minocycline and indicate that such particles might provide useful for sustained drug delivery in the CNS. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  5. Evaluation of magnesium ions release, biocorrosion, and hemocompatibility of MAO/PLLA-modified magnesium alloy WE42.

    Science.gov (United States)

    Lu, Ping; Cao, Lu; Liu, Yin; Xu, Xinhua; Wu, Xiangfeng

    2011-01-01

    Magnesium alloys may potentially be applied as biodegradable metallic materials in cardiovascular stent. However, the high corrosion rate hinders its clinical application. In this study, a new approach was adopted to control the corrosion rate by fabricating a biocompatible micro-arc oxidation/poly-L-lactic acid (MAO/PLLA) composite coating on the magnesium alloy WE42 substrate and the biocompatibility of the modified samples was investigated. The scanning electronic microscope (SEM) images were used to demonstrate the morphology of the samples before and after being submerged in hanks solution for 4 weeks. The degradation was evaluated through the magnesium ions release rate and electrochemical impedance spectroscopy (EIS) test. The biocompatibility of the samples was demonstrated by coagulation time and hemolysis behavior. The result shows that the poly-L-lactic acid (PLLA) effectively improved the corrosion resistance by sealing the microcracks and microholes on the surface of the MAO coating. The modified samples had good compatibility. © 2010 Wiley Periodicals, Inc.

  6. The influence of artificial salivary pH on nickel ion release and the surface morphology of stainless steel bracket-nickel-titanium archwire combinations

    Directory of Open Access Journals (Sweden)

    Ida Bagus Narmada

    2017-06-01

    Full Text Available Background: In the oral cavity, orthodontic appliances come into contact with saliva which may cause corrosion capable of changing their surface morphology due to the release of metal ions. Surface roughness can influence the effectiveness of tooth movement. One of the ions possibly released when body fluid comes into contact with brackets and archwire is nickel ion (Ni. Ni, one of the most popular components of orthodontic appliances, is, however, a toxic element that could potentially increase the likelihood of health problems such as allergic responses during treatment. Purpose: The purpose of this study was to investigate the effect of different artificial salivary pH on the ions released and the surface morphology of stainless steel (SS brackets-nickel-titanium (NiTi and archwire combinations. Methods: Brackets and archwires were analyzed by an Energy Dispersive X-Ray Detector System (EDX to determine their composition, while NiTi archwire compound was examined by means of X-ray Diffraction (XRD. The immersion test was performed at artificial salivary pH levels of 4.2; 6.5; and 7.6 at 37°C for 28 days. Ni ion release measurement was performed using an Atomic Absorption Spectroscopy (AAS. Surface morphology was analyzed by means of a Scanning Electron Microscopy (SEM. Results: The chemical composition of all orthodontic appliances contained Ni element. In addition, XRD was depicted phases not only NiTi but also Ni, Titanium, Silicon and Zinc Oleate. The immersion test showed that the highest release of Ni ions occured at a pH of 4.2, with no significant difference at various levels of pH (p=.092. There were surface morphology changes in the orthodontic appliances. It was revealed that at a pH of 4.2, the surfaces of orthodontic appliances become unhomogenous and rough compared to those at other pH concentrations. Conclusion: The reduction of pH in the artificial saliva increases the amount of released Ni ions, as well as causing changes to

  7. Persistence and bioavaiability of manufactured silver nanoparticles in the aquatic environment

    DEFF Research Database (Denmark)

    Dai, Lina; Banta, Gary Thomas; Selck, Henriette

    2011-01-01

    The environmental behavior of manufactured nanoparticles (MNPs) has received increasing attention. One of the focuses is whether they exist as particles or as dissolved ions in the environment. The dissolution of MNPs is a key to understand their behaviors in the environment. However, little...... information is available in dissolution of MNPs in a complex environment, such as sediment, which is believed to be the final sink for released MNPs. We tested the dissolution of PVP-coated silver nanoparticles (AgNPs) and compared the ion diffusive kinetics with Ag(I) in 3 different media (MilliQ water......, seawater and sediment) at a level of 100 µg per g dry weight sediment. A large difference in dissolution in the three media was found in the order: MilliQ water >> seawater > sediment, which suggests that ligands (i.e., organic matter and inorganic ligands) have a large influence on ion release of Ag...

  8. 含银抗菌液处理义齿软衬表面的初步研究%A Preliminary Study of Application of the Antibacterial Solution Containing Silver Ion to the Surface of Soft Lining Material

    Institute of Scientific and Technical Information of China (English)

    周密; 杜莉; 杨准; 廖运茂

    2011-01-01

    We tried to find the effects of the application of the antibacterial solution containing silver ions on the surface of the denture soft lining material. We selected the right concentraiion of the silver-containing solution and coated a soft limng material with the solution so that the soft lining material could be antibacterial. The antibacterial solution containing silver ions was prepared by sol-gel method. MIC of C. a and S. a were tested by broth dilution test.The surface property and thickness were tested after coated. The in vitro antibacterial ratio against C. a and S. a were demonstrated by the method of plate-counting. A film was formed after coating, while the adequacy was not changed. Antibacterial ratio of 0. 64 mg/ml group against C. a was 90. 82 % , and that against S. a was 94. 96% in 24 hours, respectively. It was found that the antibacterial property of the soft lining material can be acquired by coating this antibacterial solution with silver ion, without changing the adequacy.%本文采用溶胶凝胶法制备含银抗菌液,用液体稀释法测定其对白色念珠菌(C.a)和金黄色葡萄球菌(S.a)的最低抑菌浓度(MIC),将抗菌液涂层到软衬材料表面后观察膜层厚度及表面形貌;用贴膜法测定其抑菌率.结果含银抗菌液能在义齿软衬材料表面成膜,不影响义齿的适合性.0.64 mg/ml浓度的抗菌液24 h涂层的抑菌率,C.a为90.82%,S.a为94.96%,能达到较好的抑菌效果.本文制备了含银抗菌液,选择合适的浓度在义齿软衬材料表面形成抗菌涂层,含银抗菌液能赋予义齿软衬材料表面良好的抗菌性,且不影响原软衬的适合性,具有一定临床应用价值.

  9. Microwave-Assisted Synthesis of Chitosan/Polyvinyl Alcohol Silver Nanoparticles Gel for Wound Dressing Applications

    Directory of Open Access Journals (Sweden)

    Nguyen Thi Hiep

    2016-01-01

    Full Text Available The purpose of this study was to fabricate chitosan/poly(vinyl alcohol/Ag nanoparticles (CPA gels with microwave-assistance for skin applications. Microwave irradiation was employed to reduce silver ions to silver nanoparticles and to crosslink chitosan (CS with polyvinyl alcohol (PVA. The presence of silver nanoparticles in CPA gels matrix was examined using UV-Vis spectroscopy, transmission electron microscopy, and X-ray diffraction. The interaction of CS and PVA was analysed by Fourier transform infrared spectroscopy. The release of silver ions was determined by atomic absorption spectrometry. The antimicrobial properties of CPA gels against P. aeruginosa and S. aureus were investigated using agar diffusion method. Finally, the biocompatibility and wound-healing ability of the gels were studied using fibroblast cells (in vitro and mice models (in vivo. In conclusion, the results showed that CPA gels were successfully fabricated using microwave irradiation method. These gels can be applied to heal an open wound thanks to their antibacterial activity and biocompatibility.

  10. Characterisation of biosynthesised silver nanoparticles by scanning electrochemical microscopy (SECM) and voltammetry.

    Science.gov (United States)

    Battistel, Dario; Baldi, Franco; Gallo, Michele; Faleri, Claudia; Daniele, Salvatore

    2015-01-01

    Silver nanoparticles (AgNPs) were biosynthesised by a Klebsiella oxytoca strain BAS-10, which, during its growth, is known to produce a branched exopolysaccharide (EPS). Klebsiella oxytoca cultures, treated with AgNO3 and grown under either aerobic or anaerobic conditions, produced silver nanoparticles embedded in EPS (AgNPs-EPS) containing different amounts of Ag(0) and Ag(I) forms. The average size of the AgNPs-EPS was determined by transmission electron microscopy, while the relative abundance of Ag(0)- or Ag(I)-containing AgNPs-EPS was established by scanning electrochemical microscopy (SECM). Moreover, the release of silver(I) species from the various types of AgNPs-EPS was investigated by combining SECM with anodic stripping voltammetry. These measurements allowed obtaining information on the kinetic of silver ions release from AgNPs-EPS and their concentration profiles at the substrate/water interface. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Toxicity testing of four silver nanoparticle-coated dental castings in 3-D LO2 cell cultures.

    Science.gov (United States)

    Zhao, Yi-Ying; Chu, Qiang; Shi, Xu-Er; Zheng, Xiao-Dong; Shen, Xiao-Ting; Zhang, Yan-Zhen

    To address the controversial issue of the toxicity of dental alloys and silver nanoparticles in medical applications, an in vivo-like LO2 3-D model was constructed within polyvinylidene fluoride hollow fiber materials to mimic the microenvironment of liver tissue. The use of microscopy methods and the measurement of liver-specific functions optimized the model for best cell performances and also proved the superiority of the 3-D LO2 model when compared with the traditional monolayer model. Toxicity tests were conducted using the newly constructed model, finding that four dental castings coated with silver nanoparticles were toxic to human hepatocytes after cell viability assays. In general, the toxicity of both the castings and the coated silver nanoparticles aggravated as time increased, yet the nanoparticles attenuated the general toxicity by preventing metal ion release, especially at high concentrations.

  12. Potential for photocatalytic degradation of the potassic diclofenac using scandium and silver modified titanium dioxide thin films

    International Nuclear Information System (INIS)

    Ciola, R.A.; Oliveira, C.T.; Lopes, S.A.; Cavalheiro, A.A.

    2011-01-01

    The potential for photocatalytic degradation of the potassic diclofenac drug was investigated using titanium dioxide thin films modified with two modifier types, scandium and silver, both prepared by Sol-Gel method. It was demonstrated by UVVis spectroscopy analysis of the solutions containing the drug, under UV-A light irradiation that the degradation efficiency of the titanium dioxide photocatalyst is dependent of the semiconductor nature and that the scandium accelerates the first step of the degradation when compared to the silver. This result seems to be related to the redox potential of the electron-hole pair, once the scandium modifying sample generates a p type semiconductor that reduces the band gap. The extra holes attract more strongly the chorine ion present in diclofenac and leading to the releasing more easily. However, after the first byproducts degradation the following steps are not facilitated, making the silver modifying more advantageous. (author)

  13. In situ formation of antimicrobial silver nanoparticles and the impregnation of hydrophobic polycaprolactone matrix for antimicrobial medical device applications.

    Science.gov (United States)

    Tran, Phong A; Hocking, Dianna M; O'Connor, Andrea J

    2015-02-01

    Bacterial infection associated with medical devices remains a challenge to modern medicine as more patients are being implanted with medical devices that provide surfaces and environment for bacteria colonization. In particular, bacteria are commonly found to adhere more preferably to hydrophobic materials and many of which are used to make medical devices. Bacteria are also becoming increasingly resistant to common antibiotic treatments as a result of misuse and abuse of antibiotics. There is an urgent need to find alternatives to antibiotics in the prevention and treatment of device-associated infections world-wide. Silver nanoparticles have emerged as a promising non-drug antimicrobial agent which has shown effectiveness against a wide range of both Gram-negative and Gram-positive pathogen. However, for silver nanoparticles to be clinically useful, they must be properly incorporated into medical device materials whose wetting properties could be detrimental to not only the incorporation of the hydrophilic Ag nanoparticles but also the release of active Ag ions. This study aimed at impregnating the hydrophobic polycaprolactone (PCL) polymer, which is a FDA-approved polymeric medical device material, with hydrophilic silver nanoparticles. Furthermore, a novel approach was employed to uniformly, incorporate silver nanoparticles into the PCL matrix in situ and to improve the release of Ag ions from the matrix so as to enhance antimicrobial efficacy. Copyright © 2014. Published by Elsevier B.V.

  14. Gold ions bio-released from metallic gold particles reduce inflammation and apoptosis and increase the regenerative responses in focal brain injury

    DEFF Research Database (Denmark)

    Larsen, Agnete; Kolind, Kristian; Pedersen, Dan Sonne

    2008-01-01

    neural stem cell response. We conclude that bio-liberated gold ions possess pronounced anti-inflammatory and neuron-protective capacities in the brain and suggest that metallic gold has clinical potentials. Intra-cerebral application of metallic gold as a pharmaceutical source of gold ions represents......Traumatic brain injury results in loss of neurons caused as much by the resulting neuroinflammation as by the injury. Gold salts are known to be immunosuppressive, but their use are limited by nephrotoxicity. However, as we have proven that implants of pure metallic gold release gold ions which do...... not spread in the body, but are taken up by cells near the implant, we hypothesize that metallic gold could reduce local neuroinflammation in a safe way. Bio-liberation, or dissolucytosis, of gold ions from metallic gold surfaces requires the presence of disolycytes i.e. macrophages and the process...

  15. Colloidosome-based synthesis of a multifunctional nanostructure of silver and hollow iron oxide nanoparticles

    KAUST Repository

    Pan, Yue; Gao, Jinhao; Zhang, Bei; Zhang, Xixiang; Xu, Bing

    2010-01-01

    nitrate, and iron oxide exposed to the aqueous phase catalyzes the reduction of silver ions to afford a heterodimer of silver and hollow iron oxide nanoparticles. Transmission electron microscopy, selected area electron diffraction, energy-dispersive X

  16. Synthesis and antimicrobial effects of silver nanoparticles

    Directory of Open Access Journals (Sweden)

    S kheybari

    2010-09-01

    Full Text Available "n  "n "nBackground and the purpose of the study:The most prominent nanoparticles for medical uses are nanosilver particles which are famous for their high anti-microbial activity. Silver ion has been known as a metal ion that exhibit anti-mold, anti-microbial and anti-algal properties for a long time. In particular, it is widely used as silver nitrate aqueous solution which has disinfecting and sterilizing actions. The purpose of this study was to evaluate the antimicrobial activity as well as physical properties of the silver nanoparticles prepared by chemical reduction method. "nMethods:Silver nanoparticles (NPs were prepared by reduction of silver nitrate in the presence of a reducing agent and also poly [N-vinylpyrolidone] (PVP as a stabilizer. Two kinds of NPs were synthesized by ethylene glycol (EG and glucose as reducing agent. The nanostructure and particle size of silver NPs were confirmed by scanning electron microscopy (SEM and laser particle analyzer (LPA. The formations of the silver NPs were monitored using ultraviolet-visible spectroscopy. The anti-bacterial activity of silver NPs were assessed by determination of their minimum inhibitory concentrations (MIC against the Gram positive (Staphylococcus aureus and Staphylococcus epidermidis as well as Gram-negative (Escherichia coli and Pseudomonas aeruginosa bacteria. "nResults and Conclusion:The silver nanoparticles were spherical with particle size between 10 to 250 nm. Analysis of the theoretical (Mie light scattering theory and experimental results showed that the silver NPs in colloidal solution had a diameter of approximately 50 nm. "nBoth colloidal silver NPs showed high anti-bacterial activity against Gram positive and Gram negative bacteria. Glucose nanosilver colloids showed a shorter killing time against most of the tested bacteria which could be due to their nanostructures and uniform size distribution patterns.

  17. Flavor release measurement by atmospheric pressure chemical ionization ion trap mass spectrometry, construction of interface and mathematical modeling of release profiles

    DEFF Research Database (Denmark)

    Haahr, Anne-Mette; Madsen, Henrik; Smedsgaard, Jørn

    2003-01-01

    and the method can be used to measure breath from the nose. A mathematical model of the data was developed to give a quantitative method for description and characterization of the release of flavor compounds. The release profiles consisted of two sequences, one for a chewing period, and one for a phasing out...... process. The proposed method for modeling provided a reasonable description of the release process. In addition to flavor compounds, this new interface and mathematical application could provide information on chemicals in the human breath which could be interesting, for example, within medical diagnosis....... with that of the flavor detection threshold. An application study on the release of menthone and menthol from chewing gum by a group of six test persons was performed. Flavored chewing gum was used as a model matrix because of the long chewing periods and the simplicity of the system. It is concluded that the interface...

  18. Antibacterial Effect of Silver Diamine Fluoride on Cariogenic Organisms.

    Science.gov (United States)

    Lou, Yali; Darvell, Brain W; Botelho, Michael G

    2018-05-01

    To screen the possible antimicrobial activity of a range of clinically used, silver-based compounds on cariogenic organisms: silver diamine fluoride (SDF), silver fluoride, and silver nitrate. Preliminary screening disk-diffusion susceptibility tests were conducted on Mueller-Hinton agar plates inoculated with Streptococcus mutans, Lactobacillus acidophilus, and Actinomyces naeslundii, organisms known to be cariogenic. In order to identify which component of the silver compounds was responsible for any antibacterial (AB) effect, and to provide controls, the following were also investigated at high and low concentrations: sodium fluoride, ammonium fluoride, ammonium chloride, sodium fluoride, sodium chloride, and sodium nitrate, as well as deionized water as control. A volume of 10 pL of a test solution was dispensed onto a paper disk resting on the inoculated agar surface, and the plate incubated anaerobically at 37°C for 48 hours. The zones of inhibition were then measured. Silver diamine fluoride, silver fluoride, silver nitrate, and ammonium fluoride had significant AB effect (p effect at low concentration; the remaining other compounds had no effect. Silver ions appear to be the principal AB agent at both high and low concentration; fluoride ions only have an AB effect at high concentration, while ammonium, nitrate, chloride and sodium ions have none. The anticaries effect of topical silver solutions appears restricted to that of the silver ions. Silver compounds, such as SDF, silver fluoride, and silver nitrate have AB effect against cariogenic organisms and these may have clinical impact in arresting or preventing dental decay. Sodium fluoride did not have AB effect under the conditions tested.

  19. The influence of nanoscopically thin silver films on bacterial viability and attachment.

    Science.gov (United States)

    Ivanova, Elena P; Hasan, Jafar; Truong, Vi Khanh; Wang, James Y; Raveggi, Massimo; Fluke, Christopher; Crawford, Russell J

    2011-08-01

    The physicochemical and bactericidal properties of thin silver films have been analysed. Silver films of 3 and 150 nm thicknesses were fabricated using a magnetron sputtering thin-film deposition system. X-ray photoelectron and energy dispersive X-ray spectroscopy and atomic force microscopy analyses confirmed that the resulting surfaces were homogeneous, and that silver was the most abundant element present on both surfaces, being 45 and 53 at.% on the 3- and 150-nm films, respectively. Inductively coupled plasma time of flight mass spectroscopy (ICP-TOF-MS) was used to measure the concentration of silver ions released from these films. Concentrations of 0.9 and 5.2 ppb were detected for the 3- and 150-nm films, respectively. The surface wettability of the films remained nearly identical for both film thicknesses, displaying a static water contact angle of 95°, while the surface free energy of the 150-nm film was found to be slightly greater than that of the 3-nm film, being 28.8 and 23.9 mN m(-1), respectively. The two silver film thicknesses exhibited statistically significant differences in surface topographic profiles on the nanoscopic scale, with R (a), R (q) and R (max) values of 1.4, 1.8 and 15.4 nm for the 3-nm film and 0.8, 1.2 and 10.7 nm for the 150-nm film over a 5 × 5 μm scanning area. Confocal scanning laser microscopy and scanning electron microscopy revealed that the bactericidal activity of the 3-nm silver film was not significant, whereas the nanoscopically smoother 150-nm silver film exhibited appreciable bactericidal activity towards Pseudomonas aeruginosa ATCC 9027 cells and Staphylococcus aureus CIP 65.8 cells, obtaining up to 75% and 27% sterilisation effect, respectively.

  20. Effect of fluoride content on ion release from cast and selective laser melting-processed Co-Cr-Mo alloys.

    Science.gov (United States)

    Yang, Xu; Xiang, Nan; Wei, Bin

    2014-11-01

    Selective laser melting (SLM) alloy is gaining popularity in prosthetic dentistry. However, its biocompatibility has been of some concern because of long-term exposure to fluoride in the oral environment. The purpose of this study was to examine the effect of fluoride concentration on ion release from Co-Cr-Mo alloy specimens fabricated using either SLM or lost-wax casting when immersed in an artificial saliva solution containing fluoride. Specimens were prepared with either a SLM system for the SLM alloy or conventional lost-wax techniques for the cast alloy. The specimen surfaces were wet ground with silicon carbide paper (400, 800, and 1200 grit) and immersed in modified artificial saliva solutions, the pH of which had been adjusted to 5.0 with lactic acid and which contained NaF at concentrations of 0.00%, 0.05%, 0.1%, or 0.2%. The metal ion content of the solution was determined with an inductively coupled plasma mass spectrometer. The results were submitted to 2-way ANOVA and regression analysis (α=.05). Fluoride concentration significantly influenced the elemental ion release from both the SLM and cast alloys. The quantity of ions released increased significantly with increasing fluoride concentration. The ion release from the cast specimens was significantly greater than that from the SLM specimens. The performance of the SLM alloy in immersion tests demonstrates that this new technique is a superior choice because of its good biocompatibility. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  1. Interaction between Silver Nanoparticles and Spinach Leaf

    Science.gov (United States)

    Tian, Y.; Li, H.; Zhang, Y.; Riser, E.; He, S.; Zhang, W.

    2013-12-01

    Interactions of engineered nanoparticles (ENPs) with plant surfaces are critical to assessing the bioavailability of ENPs to edible plants and to further evaluating impacts of ENPs on ecological health and food safety. Silver nanoparticles (i.e., nanoAg) could enter the agroecosystems either as an active ingredient in pesticides or from other industrial and consumer applications. Thus, in the events of pesticide application, rainfall, and irrigation, vegetable leaves could become in contact and then interact with nanoAg. The present study was to assess whether the interaction of nanoAg with spinach leaves can be described by classical sorption models and to what extent it depends on and varies with dispersion methods, environmental temperature, and ion release. We investigated the stability and ion release of nanoAg dispersed by sodium dodecyl sulfate (SDS, 1%) and humic acid (HA, 10 mg C/L) solutions, as well as sorption and desorption of nanoAg on and from the fresh spinach leaf. Results showed SDS-nanoAg released about 2%-8% more Ag ion than HA-nanoAg. The sorption of Ag ion, described by the Freundlich model in the initial concentration range of 0.6-50 mg/L, was 2-4 times higher than that of nanoAg. The sorption of nanoAg on spinach leaf can be fitted by the Langmuir model, and the maximum sorption amount of HA-nanoAg and SDS-nanoAg was 0.21 and 0.41 mg/g, respectively. The higher sorption of SDS-nanoAg relative to that of HA-nanoAg could be partially resulted from the higher release of Ag ion from the former. The maximum desorption amount of HA-nanoAg and SDS-nanoAg in 1% SDS solution was 0.08 and 0.10 mg/g, respectively. NanoAg attachment on and its penetration to the spinach leaf was visualized by the Scanning Electron Microscope equipped with an Energy Dispersive Spectrometer (SEM-EDS). It is equally important that the less sorption of nanoAg under low environmental temperature could be partially due to the closure of stomata, as verified by SEM-EDS. Cyto

  2. Preparation of Palladium/Silver-Coated Polyimide Nanotubes: Flexible, Electrically Conductive Fibers

    OpenAIRE

    Lushi Kong; Guanchun Rui; Guangyu Wang; Rundong Huang; Ran Li; Jiajie Yu; Shengli Qi; Dezhen Wu

    2017-01-01

    A simple and practical method for coating palladium/silver nanoparticles on polyimide (PI) nanotubes is developed. The key steps involved in the process are silver ion exchange/reduction and displacement reactions between silver and palladium ions. With the addition of silver, the conductivity of the PI nanotubes is greatly enhanced. Further, the polyimide nanotubes with a dense, homogeneous coating of palladium nanoparticles remain flexible after heat treatment and show the possibility for u...

  3. The effect of CPP-ACP-propolis chewing gum on calcium and phosphate ion release on caries-active subjects’ saliva and the formation of Streptococcus mutans biofilm

    Science.gov (United States)

    Hasnamudhia, F.; Bachtiar, E. W.; Sahlan, M.; Soekanto, S. A.

    2017-08-01

    The aim of this study was to analyze the effect of CPP-APP and propolis wax if they are combined in a chewing gum formulation, observed from the calcium and phosphate ion level released by CPP-ACP and the emphasis of Streptococcus mutans mass in the biofilm by propolis wax on caries-active subjects’ saliva. Chewing gum simulation was done in vitro on 25 caries-active subjects’ saliva using five concentrations of chewing gum (0% propolis + 0% CPP-ACP, 0% propolis + CPP-ACP, 2% propolis + CPP-ACP,