The Experts below are selected from a list of 68406 Experts worldwide ranked by ideXlab platform
Beom Soo Kim - One of the best experts on this subject based on the ideXlab platform.
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Rapid biological synthesis of Silver Nanoparticles using plant leaf extracts
2009Co-Authors: Jae Yong Song, Beom Soo KimAbstract:Five plant leaf extracts (Pine, Persimmon, Ginkgo, Magnolia and Platanus) were used and compared for their extracellular synthesis of metallic Silver Nanoparticles. Stable Silver Nanoparticles were formed by treating aqueous solution of AgNO3 with the plant leaf extracts as reducing agent of Ag+ to Ag0. UV-visible spectroscopy was used to monitor the quantitative formation of Silver Nanoparticles. Magnolia leaf broth was the best reducing agent in terms of synthesis rate and conversion to Silver Nanoparticles. Only 11 min was required for more than 90% conversion at the reaction temperature of 95 °C using Magnolia leaf broth. The synthesized Silver Nanoparticles were characterized with inductively coupled plasma spectrometry (ICP), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and particle analyzer. The average particle size ranged from 15 to 500 nm. The particle size could be controlled by changing the reaction temperature, leaf broth concentration and AgNO3 concentration. This environmentally friendly method of biological Silver Nanoparticles production provides rates of synthesis faster or comparable to those of chemical methods and can potentially be used in various human contacting areas such as cosmetics, foods and medical applications.
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rapid biological synthesis of Silver Nanoparticles using plant leaf extracts
2009Co-Authors: Jae Yong Song, Beom Soo KimAbstract:Five plant leaf extracts (Pine, Persimmon, Ginkgo, Magnolia and Platanus) were used and compared for their extracellular synthesis of metallic Silver Nanoparticles. Stable Silver Nanoparticles were formed by treating aqueous solution of AgNO(3) with the plant leaf extracts as reducing agent of Ag(+) to Ag(0). UV-visible spectroscopy was used to monitor the quantitative formation of Silver Nanoparticles. Magnolia leaf broth was the best reducing agent in terms of synthesis rate and conversion to Silver Nanoparticles. Only 11 min was required for more than 90% conversion at the reaction temperature of 95 degrees C using Magnolia leaf broth. The synthesized Silver Nanoparticles were characterized with inductively coupled plasma spectrometry (ICP), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and particle analyzer. The average particle size ranged from 15 to 500 nm. The particle size could be controlled by changing the reaction temperature, leaf broth concentration and AgNO(3) concentration. This environmentally friendly method of biological Silver Nanoparticles production provides rates of synthesis faster or comparable to those of chemical methods and can potentially be used in various human contacting areas such as cosmetics, foods and medical applications.
Jae Yong Song - One of the best experts on this subject based on the ideXlab platform.
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Rapid biological synthesis of Silver Nanoparticles using plant leaf extracts
2009Co-Authors: Jae Yong Song, Beom Soo KimAbstract:Five plant leaf extracts (Pine, Persimmon, Ginkgo, Magnolia and Platanus) were used and compared for their extracellular synthesis of metallic Silver Nanoparticles. Stable Silver Nanoparticles were formed by treating aqueous solution of AgNO3 with the plant leaf extracts as reducing agent of Ag+ to Ag0. UV-visible spectroscopy was used to monitor the quantitative formation of Silver Nanoparticles. Magnolia leaf broth was the best reducing agent in terms of synthesis rate and conversion to Silver Nanoparticles. Only 11 min was required for more than 90% conversion at the reaction temperature of 95 °C using Magnolia leaf broth. The synthesized Silver Nanoparticles were characterized with inductively coupled plasma spectrometry (ICP), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and particle analyzer. The average particle size ranged from 15 to 500 nm. The particle size could be controlled by changing the reaction temperature, leaf broth concentration and AgNO3 concentration. This environmentally friendly method of biological Silver Nanoparticles production provides rates of synthesis faster or comparable to those of chemical methods and can potentially be used in various human contacting areas such as cosmetics, foods and medical applications.
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rapid biological synthesis of Silver Nanoparticles using plant leaf extracts
2009Co-Authors: Jae Yong Song, Beom Soo KimAbstract:Five plant leaf extracts (Pine, Persimmon, Ginkgo, Magnolia and Platanus) were used and compared for their extracellular synthesis of metallic Silver Nanoparticles. Stable Silver Nanoparticles were formed by treating aqueous solution of AgNO(3) with the plant leaf extracts as reducing agent of Ag(+) to Ag(0). UV-visible spectroscopy was used to monitor the quantitative formation of Silver Nanoparticles. Magnolia leaf broth was the best reducing agent in terms of synthesis rate and conversion to Silver Nanoparticles. Only 11 min was required for more than 90% conversion at the reaction temperature of 95 degrees C using Magnolia leaf broth. The synthesized Silver Nanoparticles were characterized with inductively coupled plasma spectrometry (ICP), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and particle analyzer. The average particle size ranged from 15 to 500 nm. The particle size could be controlled by changing the reaction temperature, leaf broth concentration and AgNO(3) concentration. This environmentally friendly method of biological Silver Nanoparticles production provides rates of synthesis faster or comparable to those of chemical methods and can potentially be used in various human contacting areas such as cosmetics, foods and medical applications.
Humberto H. Lara - One of the best experts on this subject based on the ideXlab platform.
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bactericidal effect of Silver Nanoparticles against multidrug resistant bacteria
2010Co-Authors: Humberto H. Lara, Nilda Vanesa Ayalanunez, Liliana Del Carmen Ixtepan Turrent, Cristina Rodriguez PadillaAbstract:Infections caused by drug-resistant microorganisms result in significant increases in mortality, morbidity, and cost related to prolonged treatments. The antibacterial activity of Silver Nanoparticles against some drug-resistant bacteria has been established, but further investigation is needed to determine whether these particles could be an option for the treatment and prevention of drug-resistant microbial infections. Hence, we challenged different drug-resistant pathogens of clinical importance (multidrug-resistant Pseudomonas aeruginosa, ampicillin-resistant Escherichia coli O157:H7 and erythromycin-resistant Streptococcus pyogenes) with a suspension of Silver Nanoparticles. By means of a luciferase-based assay, it was determined that Silver Nanoparticles (1) inactivate a panel of drug-resistant and drug-susceptible bacteria (Gram positive and Gram negative), (2) exert their antibacterial activity through a bactericidal rather than bacteriostatic mechanism, and (3) inhibit the bacterial growth rate from the time of first contact between the bacteria and the Nanoparticles. Additionally, strains with a resistant phenotype to Silver nanoparticle were developed and used to explore the bactericidal mode of action of Silver Nanoparticles. Through a Kirby–Bauer test, it was shown that Silver Nanoparticles’ general mechanism of bactericidal action is based on inhibition of cell wall synthesis, protein synthesis mediated by the 30s ribosomal subunit, and nucleic acid synthesis. Our data suggest that Silver Nanoparticles are effective broad-spectrum biocides against a variety of drug-resistant bacteria, which makes them a potential candidate for use in pharmaceutical products and medical devices that may help to prevent the transmission of drug-resistant pathogens in different clinical environments.
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Mode of antiviral action of Silver Nanoparticles against HIV-1
2010Co-Authors: Humberto H. Lara, Nilda V Ayala-nuñez, Liliana Ixtepan-turrent, Cristina Rodriguez-padillaAbstract:Background Silver Nanoparticles have proven to exert antiviral activity against HIV-1 at non-cytotoxic concentrations, but the mechanism underlying their HIV-inhibitory activity has not been not fully elucidated. In this study, Silver Nanoparticles are evaluated to elucidate their mode of antiviral action against HIV-1 using a panel of different in vitro assays. Results Our data suggest that Silver Nanoparticles exert anti-HIV activity at an early stage of viral replication, most likely as a virucidal agent or as an inhibitor of viral entry. Silver Nanoparticles bind to gp120 in a manner that prevents CD4-dependent virion binding, fusion, and infectivity, acting as an effective virucidal agent against cell-free virus (laboratory strains, clinical isolates, T and M tropic strains, and resistant strains) and cell-associated virus. Besides, Silver Nanoparticles inhibit post-entry stages of the HIV-1 life cycle. Conclusions These properties make them a broad-spectrum agent not prone to inducing resistance that could be used preventively against a wide variety of circulating HIV-1 strains.
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Interaction of Silver Nanoparticles with HIV-1
2005Co-Authors: Jose Luis Elechiguerra, Jose Ruben Morones, Alejandra Camacho-bragado, Humberto H. Lara, Xiaoxia Gao, Justin L. Burt, Miguel Jose YacamanAbstract:The interaction of Nanoparticles with biomolecules and microorganisms is an expanding field of research. Within this field, an area that has been largely unexplored is the interaction of metal Nanoparticles with viruses. In this work, we demonstrate that Silver Nanoparticles undergo a size-dependent interaction with HIV-1, with Nanoparticles exclusively in the range of 1-10 nm attached to the virus. The regular spatial arrangement of the attached Nanoparticles, the center-to-center distance between Nanoparticles, and the fact that the exposed sulfur-bearing residues of the glycoprotein knobs would be attractive sites for nanoparticle interaction suggest that Silver Nanoparticles interact with the HIV-1 virus via preferential binding to the gp120 glycoprotein knobs. Due to this interaction, Silver Nanoparticles inhibit the virus from binding to host cells, as demonstrated in vitro.
Chi Ming Che - One of the best experts on this subject based on the ideXlab platform.
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Silver Nanoparticles inhibit hepatitis b virus replication
2008Co-Authors: Raymond Waiyin Sun, Rong Chen, Cheekin Hui, John M Luk, George K K Lau, Chi Ming CheAbstract:BACKGROUND Silver Nanoparticles have been shown to exhibit promising cytoprotective activities towards HIV-infected T-cells; however, the effects of these Nanoparticles towards other kinds of viruses remain largely unexplored. The aim of the present study was to investigate the effects of Silver Nanoparticles on hepatitis B virus (HBV). METHODS Monodisperse Silver Nanoparticles with mean particle diameters of approximately 10 nm (Ag10Ns) and approximately 50 nm (Ag50Ns) were prepared from AgNO3 in HEPES buffer. The in vitro anti-HBV activities of these particles were determined using the HepAD38 cell line as infection model. RESULTS Ag10Ns and Ag50Ns were able to reduce the extracellular HBV DNA formation of HepAD38 cells by >50% compared with the vehicle control (that is, HepAD38 cells in the absence of Silver Nanoparticles). Silver Nanoparticles had little effect on the amount of HBV covalently closed circular DNA (cccDNA), but could inhibit the formation of intracellular HBV RNA. Gel mobility shift assays indicated that Ag10Ns bound HBV double-stranded DNA at a DNA:Silver molar ratio of 1:50; an absorption titration assay showed that the Nanoparticles have good binding affinity for HBV DNA with a binding constant (Kb) of (8.8 +/- 1.0)x10(5) dm(3)mol(-1). As both the viral and Ag10Ns systems are in the nanometer size range, we found that Ag10Ns could directly interact with the HBV viral particles as revealed by transmission electronic microscopy. CONCLUSIONS Silver Nanoparticles could inhibit the in vitro production of HBV RNA and extracellular virions. We hypothesize that the direct interaction between these Nanoparticles and HBV double-stranded DNA or viral particles is responsible for their antiviral mechanism.
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topical delivery of Silver Nanoparticles promotes wound healing
2007Co-Authors: Jun Tian, Chi Ming Che, Jen-fu Chiu, Chun-nam Lok, Kenneth Kak Yuen Wong, Paul K H TamAbstract:Wound healing is a complex process and has been the subject of intense research for a long time. The recent emergence of nanotechnology has provided a new therapeutic modality in Silver Nanoparticles for use in burn wounds. Nonetheless, the beneficial effects of Silver Nanoparticles on wound healing remain unknown. We investigated the wound-healing properties of Silver Nanoparticles in an animal model and found that rapid healing and improved cosmetic appearance occur in a dose-dependent manner. Furthermore, through quantitative PCR, immunohistochemistry, and proteomic studies, we showed that Silver Nanoparticles exert positive effects through their antimicrobial properties, reduction in wound inflammation, and modulation of fibrogenic cytokines. These results have given insight into the actions of Silver and have provided a novel therapeutic direction for wound treatment in clinical practice.
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Silver Nanoparticles: partial oxidation and antibacterial activities.
2007Co-Authors: Chun-nam Lok, Wing-yiu Yu, Paul Kwong-hang Tam, Chi-ming Ho, Jen-fu Chiu, Qing-yu He, Hongzhe Sun, Rong Chen, Chi Ming CheAbstract:The physical and chemical properties of Silver Nanoparticles that are responsible for their antimicrobial activities have been studied with spherical Silver Nanoparticles (average diameter approximately 9 nm) synthesized by the borohydride reduction of Ag+ ions, in relation to their sensitivity to oxidation, activities towards Silver-resistant bacteria, size-dependent activities, and dispersal in electrolytic solutions. Partially (surface) oxidized Silver Nanoparticles have antibacterial activities, but zero-valent Nanoparticles do not. The levels of chemisorbed Ag+ that form on the particle's surface, as revealed by changes in the surface plasmon resonance absorption during oxidation and reduction, correlate well with the observed antibacterial activities. Silver Nanoparticles, like Ag+ in the form of AgNO3 solution, are tolerated by the bacteria strains resistant to Ag+. The antibacterial activities of Silver Nanoparticles are related to their size, with the smaller particles having higher activities on the basis of equivalent Silver mass content. The Silver Nanoparticles aggregate in media with a high electrolyte content, resulting in a loss of antibacterial activities. However, complexation with albumin can stabilize the Silver Nanoparticles against aggregation, leading to a retention of the antibacterial activities. Taken together, the results show that the antibacterial activities of Silver Nanoparticles are dependent on chemisorbed Ag+, which is readily formed owing to extreme sensitivity to oxygen. The antibacterial activities of Silver Nanoparticles are dependent on optimally displayed oxidized surfaces, which are present in well-dispersed suspensions.
R H Alasubramanya - One of the best experts on this subject based on the ideXlab platform.
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biological synthesis of Silver Nanoparticles using the fungus aspergillus flavus
2007Co-Authors: N Vigneshwara, R P Nachane, N M Ashtaputre, P V Varadaraja, K M Paralika, R H AlasubramanyaAbstract:Abstract The fungus, Aspergillus flavus when challenged with Silver nitrate solution accumulated Silver Nanoparticles on the surface of its cell wall in 72 h. These Nanoparticles dislodged by ultrasonication showed an absorption peak at 420 nm in UV–visible spectrum corresponding to the plasmon resonance of Silver Nanoparticles. The transmission electron micrographs of dislodged Nanoparticles in aqueous solution showed the production of reasonably monodisperse Silver Nanoparticles (average particle size: 8.92 ± 1.61 nm) by the fungus. X-ray diffraction spectrum of the Nanoparticles confirmed the formation of metallic Silver. The Fourier transform infrared spectroscopy confirmed the presence of protein as the stabilizing agent surrounding the Silver Nanoparticles. These protein-stabilized Silver Nanoparticles produced a characteristic emission peak at 553 nm when excited at 420 nm in photoluminescence spectrum. The use of fungus for Silver Nanoparticles synthesis offers the benefits of eco-friendliness and amenability for large-scale production.
