The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
Herman Autrup - One of the best experts on this subject based on the ideXlab platform.
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toxicity of Silver nanoparticles nanoparticle or Silver Ion
Toxicology Letters, 2012Co-Authors: Christiane Beer, Rasmus Foldbjerg, Yuya Hayashi, Duncan S Sutherland, Herman AutrupAbstract:Abstract The toxicity of Silver nanoparticles (AgNPs) has been shown in many publicatIons. Here we investigated to which degree the Silver Ion fractIon of AgNP suspensIons, contribute to the toxicity of AgNPs in A549 lung cells. Cell viability assays revealed that AgNP suspensIons were more toxic when the initial Silver Ion fractIon was higher. At 1.5 μg/ml total Silver, A549 cells exposed to an AgNP suspensIon containing 39% Silver Ion fractIon showed a cell viability of 92%, whereas cells exposed to an AgNP suspensIon containing 69% Silver Ion fractIon had a cell viability of 54% as measured by the MTT assay. In additIon, at initial Silver Ion fractIons of 5.5% and above, AgNP-free supernatant had the same toxicity as AgNP suspensIons. Flow-cytometric analyses of cell cycle and apoptosis confirmed that there is no significant difference between the treatment with AgNP suspensIon and AgNP supernatant. Only AgNP suspensIons with Silver Ion fractIon of 2.6% or less were significantly more toxic than their supernatant as measured by MTT assays. From our data we conclude that at high Silver Ion fractIons (≥5.5%) the AgNPs did not add measurable additIonal toxicity to the AgNP suspensIon, whereas at low Silver Ion fractIons (≤2.6%) AgNP suspensIons are more toxic than their supernatant.
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Toxicity of Silver nanoparticles-Nanoparticle or Silver Ion?
Toxicology Letters, 2012Co-Authors: Christiane Beer, Rasmus Foldbjerg, Yuya Hayashi, Duncan S Sutherland, Herman AutrupAbstract:The toxicity of Silver nanoparticles (AgNPs) has been shown in many publicatIons. Here we investigated to which degree the Silver Ion fractIon of AgNP suspensIons, contribute to the toxicity of AgNPs in A549 lung cells. Cell viability assays revealed that AgNP suspensIons were more toxic when the initial Silver Ion fractIon was higher. At 1.5 μg/ml total Silver, A549 cells exposed to an AgNP suspensIon containing 39% Silver Ion fractIon showed a cell viability of 92%, whereas cells exposed to an AgNP suspensIon containing 69% Silver Ion fractIon had a cell viability of 54% as measured by the MTT assay. In additIon, at initial Silver Ion fractIons of 5.5% and above, AgNP-free supernatant had the same toxicity as AgNP suspensIons. Flow-cytometric analyses of cell cycle and apoptosis confirmed that there is no significant difference between the treatment with AgNP suspensIon and AgNP supernatant. Only AgNP suspensIons with Silver Ion fractIon of 2.6% or less were significantly more toxic than their supernatant as measured by MTT assays. From our data we conclude that at high Silver Ion fractIons (≥5.5%) the AgNPs did not add measurable additIonal toxicity to the AgNP suspensIon, whereas at low Silver Ion fractIons (≤2.6%) AgNP suspensIons are more toxic than their supernatant. © 2011 Elsevier Ireland Ltd.
Subramanian Ramasamy - One of the best experts on this subject based on the ideXlab platform.
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CharacterizatIon of a Silver-Ion conducting solid-state battery with a new compact battery discharge unit
Journal of Power Sources, 2002Co-Authors: R. Murugaraj, G. Govindaraj, Subramanian RamasamyAbstract:Abstract The polarizatIon and discharge characteristics of solid-state batteries are examined by means of a conventIonal load resistor technique with high-performance mV or μA meters. In the present paper, to overcome the need for high-performance meters, a compact discharge–polarizatIon unit is constructed. The new discharge unit does not require any other high input impedance accessories like, mV or μA meters. It is used to study the polarizatIon and discharge characteristics of Silver-Ion conducting electrolytes such as: (a) the polycrystalline system: ((CH 3 ) 4 N) 2 Ag 13 I 15 ; (b) the Silver boro-vanadate glassy system: AgI–Ag 2 O–B 2 O 3 –V 2 O 5 ; (c) the Silver boro-molybdate glassy system: AgI–Ag 2 O–B 2 O 3 –MoO 3 . Solid-state batteries are fabricated with different cathode materials at various compositIons and battery performance is studied with the new battery discharge unit.
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CharacterizatIon of a Silver-Ion conducting solid-state battery with a new compact battery discharge unit
Journal of Power Sources, 2002Co-Authors: R. Murugaraj, G. Govindaraj, Subramanian RamasamyAbstract:The polarizatIon and discharge characteristics of solid-state batteries are examined by means of a conventIonal load resistor technique with high-performance mV or μA meters. In the present paper, to overcome the need for high-performance meters, a compact discharge-polarizatIon unit is constructed. The new discharge unit does not require any other high input impedance accessories like, mV or μA meters. It is used to study the polarizatIon and discharge characteristics of Silver-Ion conducting electrolytes such as: (a) the polycrystalline system: ((CH3)4N)2Ag13I15; (b) the Silver boro-vanadate glassy system: AgI-Ag2O-B2O3-V2O5; (c) the Silver boro-molybdate glassy system: AgI-Ag2O-B2O3-MoO3. Solid-state batteries are fabricated with different cathode materials at various compositIons and battery performance is studied with the new battery discharge unit. © 2002 Elsevier Science B.V. All rights reserved.
Christiane Beer - One of the best experts on this subject based on the ideXlab platform.
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toxicity of Silver nanoparticles nanoparticle or Silver Ion
Toxicology Letters, 2012Co-Authors: Christiane Beer, Rasmus Foldbjerg, Yuya Hayashi, Duncan S Sutherland, Herman AutrupAbstract:Abstract The toxicity of Silver nanoparticles (AgNPs) has been shown in many publicatIons. Here we investigated to which degree the Silver Ion fractIon of AgNP suspensIons, contribute to the toxicity of AgNPs in A549 lung cells. Cell viability assays revealed that AgNP suspensIons were more toxic when the initial Silver Ion fractIon was higher. At 1.5 μg/ml total Silver, A549 cells exposed to an AgNP suspensIon containing 39% Silver Ion fractIon showed a cell viability of 92%, whereas cells exposed to an AgNP suspensIon containing 69% Silver Ion fractIon had a cell viability of 54% as measured by the MTT assay. In additIon, at initial Silver Ion fractIons of 5.5% and above, AgNP-free supernatant had the same toxicity as AgNP suspensIons. Flow-cytometric analyses of cell cycle and apoptosis confirmed that there is no significant difference between the treatment with AgNP suspensIon and AgNP supernatant. Only AgNP suspensIons with Silver Ion fractIon of 2.6% or less were significantly more toxic than their supernatant as measured by MTT assays. From our data we conclude that at high Silver Ion fractIons (≥5.5%) the AgNPs did not add measurable additIonal toxicity to the AgNP suspensIon, whereas at low Silver Ion fractIons (≤2.6%) AgNP suspensIons are more toxic than their supernatant.
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Toxicity of Silver nanoparticles-Nanoparticle or Silver Ion?
Toxicology Letters, 2012Co-Authors: Christiane Beer, Rasmus Foldbjerg, Yuya Hayashi, Duncan S Sutherland, Herman AutrupAbstract:The toxicity of Silver nanoparticles (AgNPs) has been shown in many publicatIons. Here we investigated to which degree the Silver Ion fractIon of AgNP suspensIons, contribute to the toxicity of AgNPs in A549 lung cells. Cell viability assays revealed that AgNP suspensIons were more toxic when the initial Silver Ion fractIon was higher. At 1.5 μg/ml total Silver, A549 cells exposed to an AgNP suspensIon containing 39% Silver Ion fractIon showed a cell viability of 92%, whereas cells exposed to an AgNP suspensIon containing 69% Silver Ion fractIon had a cell viability of 54% as measured by the MTT assay. In additIon, at initial Silver Ion fractIons of 5.5% and above, AgNP-free supernatant had the same toxicity as AgNP suspensIons. Flow-cytometric analyses of cell cycle and apoptosis confirmed that there is no significant difference between the treatment with AgNP suspensIon and AgNP supernatant. Only AgNP suspensIons with Silver Ion fractIon of 2.6% or less were significantly more toxic than their supernatant as measured by MTT assays. From our data we conclude that at high Silver Ion fractIons (≥5.5%) the AgNPs did not add measurable additIonal toxicity to the AgNP suspensIon, whereas at low Silver Ion fractIons (≤2.6%) AgNP suspensIons are more toxic than their supernatant. © 2011 Elsevier Ireland Ltd.
R. Murugaraj - One of the best experts on this subject based on the ideXlab platform.
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CharacterizatIon of a Silver-Ion conducting solid-state battery with a new compact battery discharge unit
Journal of Power Sources, 2002Co-Authors: R. Murugaraj, G. Govindaraj, Subramanian RamasamyAbstract:Abstract The polarizatIon and discharge characteristics of solid-state batteries are examined by means of a conventIonal load resistor technique with high-performance mV or μA meters. In the present paper, to overcome the need for high-performance meters, a compact discharge–polarizatIon unit is constructed. The new discharge unit does not require any other high input impedance accessories like, mV or μA meters. It is used to study the polarizatIon and discharge characteristics of Silver-Ion conducting electrolytes such as: (a) the polycrystalline system: ((CH 3 ) 4 N) 2 Ag 13 I 15 ; (b) the Silver boro-vanadate glassy system: AgI–Ag 2 O–B 2 O 3 –V 2 O 5 ; (c) the Silver boro-molybdate glassy system: AgI–Ag 2 O–B 2 O 3 –MoO 3 . Solid-state batteries are fabricated with different cathode materials at various compositIons and battery performance is studied with the new battery discharge unit.
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CharacterizatIon of a Silver-Ion conducting solid-state battery with a new compact battery discharge unit
Journal of Power Sources, 2002Co-Authors: R. Murugaraj, G. Govindaraj, Subramanian RamasamyAbstract:The polarizatIon and discharge characteristics of solid-state batteries are examined by means of a conventIonal load resistor technique with high-performance mV or μA meters. In the present paper, to overcome the need for high-performance meters, a compact discharge-polarizatIon unit is constructed. The new discharge unit does not require any other high input impedance accessories like, mV or μA meters. It is used to study the polarizatIon and discharge characteristics of Silver-Ion conducting electrolytes such as: (a) the polycrystalline system: ((CH3)4N)2Ag13I15; (b) the Silver boro-vanadate glassy system: AgI-Ag2O-B2O3-V2O5; (c) the Silver boro-molybdate glassy system: AgI-Ag2O-B2O3-MoO3. Solid-state batteries are fabricated with different cathode materials at various compositIons and battery performance is studied with the new battery discharge unit. © 2002 Elsevier Science B.V. All rights reserved.
Helmut Munstedt - One of the best experts on this subject based on the ideXlab platform.
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Silver Ion Release from Antimicrobial Acrylate Photopolymer Layers
Polymers & Polymer Composites, 2009Co-Authors: C. Damm, Helmut MunstedtAbstract:Crosslinked Silver-filled acrylate photopolymer layers on polyetheretherketone (PEEK) films were prepared by a heterogeneous photocatalytic polymerisatIon initiatIon using Silver-coated titanium dioxide as a catalyst material. The Silver Ion release from 5 μm thick acrylate photopolymer layers was studied as a functIon of the chemical structure of the polymer matrix. The Silver Ion release increases with the number of ethoxy groups per monomer unit, although the filler content in all acrylate samples was the same (2.5 wt.% titanium dioxide coated with 1 mol.% elemental Ag). This finding can be explained on the basis of the water uptake of the polymer matrix: Silver Ions are generated from elemental Silver particles only in the presence of water. The maximum water absorptIon of the photopolymers as well as the diffusIon coefficient of water in the polymers increases with the number of hydrophilic ethoxy groups per monomer unit. The Silver Ion release from the acrylate photopolymer layers is governed by diffusIon. The diffusIon coefficient of Silver Ions, however, is at least two orders of magnitude smaller than that of water. This finding suggests that the interactIons between Silver Ions and the polymers and/or the titanium dioxide must be stronger than the interactIons between water molecules and the polymers and/or the titanium dioxide because the mobility of a diffusing species decreases if the interactIons with the surrounding matrix become stronger. Acrylate photopolymer layers containing at least 6 ethoxy groups per monomer unit release an amount of Silver Ions of 3 μg * l -1* cm -2 or more per day. This amount is sufficient to eliminate Escherichia coli completely within 24 h.
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kinetic aspects of the Silver Ion release from antimicrobial polyamide Silver nanocomposites
Applied Physics A, 2008Co-Authors: Cornelia Damm, Helmut MunstedtAbstract:Spherical Silver nanoparticles were grown in situ in different polyamides by a thermal reductIon of Silver acetate during melt processing of the polymers. Most of the particles have a diameter of about 20 nm. The absolute amount as well as the kinetics of the Silver Ion release from the various polyamide/Silver nanocomposites differ strongly, although the filler content in all materials is the same (1.5 wt. %) and the morphologies of the Silver particles are not very different. One result of the investigatIons was that the absolute amount of the long-term Silver Ion release increases exponentially with the maximum water absorptIon of the polymers used as matrix materials, because Silver Ions are formed from elemental Silver particles in the presence of water, only. Moreover, it was also found that the long-term Silver Ion release increases with a growing diffusIon coefficient of water in the polymer. The water absorptIon properties of the polymers govern the kinetics of the Silver Ion release, too: for strong hydrophilic polyamides like PA6 or PA6.6, which are plasticized by water, the Silver Ion release is a zero-order process. For nanocomposites with less hydrophilic polyamides like a cycloaliphatic polyamide or a P12 modified with polytetrahydrofurane (PA12-poly-THF), the Silver Ion release is governed by diffusIon. As expected from the efficacy of the Silver Ion release, PA6, PA6.6, PA12 and PA12 modified with polytetrahydrofurane and a cycloaliphatic polyamide filled with 1.5 wt. % of Silver nanoparticles are active against Escherichia coli. But, only nanocomposites with PA6, PA6.6 and P12-poly-THF as matrix materials are suitable as long-term biocidal materials.
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Kinetic aspects of the Silver Ion release from antimicrobial polyamide/Silver nanocomposites
Applied Physics A, 2008Co-Authors: Cornelia Damm, Helmut MunstedtAbstract:Spherical Silver nanoparticles were grown in situ in different polyamides by a thermal reductIon of Silver acetate during melt processing of the polymers. Most of the particles have a diameter of about 20 nm. The absolute amount as well as the kinetics of the Silver Ion release from the various polyamide/Silver nanocomposites differ strongly, although the filler content in all materials is the same (1.5 wt. %) and the morphologies of the Silver particles are not very different. One result of the investigatIons was that the absolute amount of the long-term Silver Ion release increases exponentially with the maximum water absorptIon of the polymers used as matrix materials, because Silver Ions are formed from elemental Silver particles in the presence of water, only. Moreover, it was also found that the long-term Silver Ion release increases with a growing diffusIon coefficient of water in the polymer. The water absorptIon properties of the polymers govern the kinetics of the Silver Ion release, too: for strong hydrophilic polyamides like PA6 or PA6.6, which are plasticized by water, the Silver Ion release is a zero-order process. For nanocomposites with less hydrophilic polyamides like a cycloaliphatic polyamide or a P12 modified with polytetrahydrofurane (PA12-poly-THF), the Silver Ion release is governed by diffusIon. As expected from the efficacy of the Silver Ion release, PA6, PA6.6, PA12 and PA12 modified with polytetrahydrofurane and a cycloaliphatic polyamide filled with 1.5 wt. % of Silver nanoparticles are active against Escherichia coli. But, only nanocomposites with PA6, PA6.6 and P12-poly-THF as matrix materials are suitable as long-term biocidal materials.
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polyamide Silver antimicrobials effect of filler types on the Silver Ion release
Journal of Biomedical Materials Research Part B, 2005Co-Authors: Radhesh Kumar, S M Howdle, Helmut MunstedtAbstract:Abstract: The efficiency of various Silver-based antimicrobial fillers (elementary Silver and Silver substituted materials) in polyamide (PA) toward their Silver Ion (Ag�) release characteristics in an aqueous medium was investigated and discussed. Anode stripping voltammetry (ASV) was used for the quantitative estimatIon of Ag� release from these composites. The biocidal (Ag�) release from the composites was found to be dependent on the time of soaking in water and the nature of the filler. The long-term Ag� release capability of the elementary Silver-based PA/Ag composite is promising compared with the commercial counterparts. The Silver Ion release potential of polyamide composites where the Silver filling was performed by using supercritical carbon dioxide (scCO2) is also discussed. The composites release Ag� at a concentratIon level capable of rendering antimicrobial efficacy and proved to be active against the microbes. A good agreement exists between the Ag� release experiments and antimicrobial test results. The observed results on the influence of the nature of the filler and crystallinity on the biocidal release and the varying long-term release properties could be helpful in the design of industrially relevant biomaterials. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 75B: 311–319, 2005
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polyamide Silver antimicrobials effect of crystallinity on the Silver Ion release
Polymer International, 2005Co-Authors: Radhesh Kumar, Helmut MunstedtAbstract:Polyamide/Silver (PA/Ag) composite materials are regarded as potential antimicrobials by virtue of their efficacy to release the Ag+ Ions in an aqueous medium. The effects of the matrix crystallinity on the Ag+ Ion release characteristics of PA/Ag composites are discussed. It is found that matrix crystallinity is very decisive for the Silver Ion releasing properties and hence the antimicrobial efficacy of Silver-based antimicrobial polyamides. The crystallinities of the composites were evaluated using differential scanning calorimetry. The Silver Ion release characteristics of these composites were measured by anode stripping voltammetry. Silver Ion release was higher in systems possessing lower degrees of crystallinity. Water-diffusIon characteristics of the composites control the Silver Ion release. The effect of crystallinity on Silver Ion release rate depends on the time of soaking of the specimens in water. Copyright © 2005 Society of Chemical Industry
