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Colloidal silver

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https://www.readbyqxmd.com/read/28732869/in-situ-formation-of-supramolecular-aggregates-between-chitin-nanofibers-and-silver-nanoparticles
#1
Ruchira N Wijesena, Nadeeka D Tissera, Charith Abeyratne, Osura M Bangamuwa, Natalie Ludowyke, Damayanthi Dahanayake, Sunanda Gunasekara, Nuwan de Silva, Rohini M de Silva, K M Nalin de Silva
Chitin and chitin derivatives have gained significant research interest over the years due to a number of beneficial properties that can be exploited in various application fields. Particularly, interactions between their nanostructures and other nanomaterials are of great interest. In situ photo-reduction of AgCl in chitin nanofiber aqueous dispersions resulted in significant loss of colloidal stability of both chitin nanofibers (CNF) and silver nanoparticles. UV-vis spectroscopy was used to characterize the extinction profiles of in-situ prepared CNF and several silver nanoparticle mixtures over the reaction steps...
October 1, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28732010/biofilm-imaging-in-porous-media-by-laboratory-x-ray-tomography-combining-a-non-destructive-contrast-agent-with-propagation-based-phase-contrast-imaging-tools
#2
Maxence Carrel, Mario A Beltran, Verónica L Morales, Nicolas Derlon, Eberhard Morgenroth, Rolf Kaufmann, Markus Holzner
X-ray tomography is a powerful tool giving access to the morphology of biofilms, in 3D porous media, at the mesoscale. Due to the high water content of biofilms, the attenuation coefficient of biofilms and water are very close, hindering the distinction between biofilms and water without the use of contrast agents. Until now, the use of contrast agents such as barium sulfate, silver-coated micro-particles or 1-chloronaphtalene added to the liquid phase allowed imaging the biofilm 3D morphology. However, these contrast agents are not passive and potentially interact with the biofilm when injected into the sample...
2017: PloS One
https://www.readbyqxmd.com/read/28727434/ellipsometry-of-colloidal-solutions-new-experimental-setup-and-application-to-metallic-colloids
#3
Yann Battie, Michel Stchakovsky, Aotmane En Naciri, Suzanna Akil, Nouari Chaoui, Laurent Broch
An ellipsometric cell is developed to simultaneously determine the shape distribution, the volume fraction, and the complex refractive index of gold and silver colloids. Simulation reveals that this cell drastically improves the detection limit of ellipsometry. Indeed, Ag and Au nanoparticles (NPs) are detected at the ppmv level. We demonstrate that the NPs shape distribution can be estimated from ellipsometric measurements by analyzing them with a shape distributed effective medium theory (SDEMT). The obtained distributions from ellipsometry are in agreement with those deduced from transmission electron microcopy (TEM)...
July 20, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28715772/stability-of-single-dispersed-silver-nanoparticles-in-natural-and-synthetic-freshwaters-effects-of-dissolved-oxygen
#4
Xiaoyan Zou, Penghui Li, Jie Lou, Xiaoyan Fu, Hongwu Zhang
Silver nanoparticles (AgNPs) are increasingly used in various commercial products. This increased use raises ecological concerns because of the large release of AgNPs into the environment. Once released, the local water chemistry has the potential to influence the environmental fates and behaviors of AgNPs. The impacts of dissolved oxygen and natural organic matter (NOM) on the dissolution and stability of AgNPs were investigated in synthetic and natural freshwaters for 7 days. In synthetic freshwater, the aggregation of AgNPs occurred due to the compression of the electric double layer, accompanied by the dissolution of AgNPs...
July 14, 2017: Environmental Pollution
https://www.readbyqxmd.com/read/28710015/bactericidal-impact-of-ag-zno-and-mixed-agzno-colloidal-nanoparticles-on-h37rv-mycobacterium-tuberculosis-phagocytized-by-thp-1%C3%A2-cell-lines
#5
Alireza Jafari, Nader Mosavari, Farahnaz Movahedzadeh, Saeedeh Jafari Nodooshan, Roya Safarkar, Rossella Moro, Morteza Kamalzadeh, Ali Majidpour, Mina Boustanshenas, Tahereh Mosavi
The purpose of this research project was to infection of human macrophages (THP-1) cell lines by H37Rv strain of Mycobacterium tuberculosis (H37RvMTB) and find out the ratio/dilution of mixture silver (Ag NPs) and zinc oxide nanoparticles (ZnO NPs) whose ability to eliminate phagocytized bacteria compared to rifampicin. The colloidal Ag NPs and ZnO NPs were synthesized and their characteristics were evaluated. The THP-1 cell lines were infected with different concentration of H37RvMTB. Next, the infected cells were treated with different ratios/dilutions of Ag NPs, ZnO NPs and rifampicin...
July 11, 2017: Microbial Pathogenesis
https://www.readbyqxmd.com/read/28685107/optical-response-of-heterogeneous-polymer-layers-containing-silver-nanostructures
#6
Miriam Carlberg, Florent Pourcin, Olivier Margeat, Judikaël Le Rouzo, Gérard Berginc, Rose-Marie Sauvage, Jörg Ackermann, Ludovic Escoubas
This work is focused on the study of the optical properties of silver nanostructures embedded in a polymer host matrix. The introduction of silver nanostructures in polymer thin films is assumed to result in layers having adaptable optical properties. Thin film layers with inclusions of differently shaped nanoparticles, such as nanospheres and nanoprisms, and of different sizes, are optically characterized. The nanoparticles are produced by a simple chemical synthesis at room temperature in water. The plasmonic resonance peaks of the different colloidal solutions range from 390 to 1300 nm...
2017: Beilstein Journal of Nanotechnology
https://www.readbyqxmd.com/read/28683369/aggregation-based-colorimetric-sensor-for-determination-of-prothioconazole-fungicide-using-colloidal-silver-nanoparticles-agnps
#7
Zahra Jafar-Nezhad Ivrigh, Nafiseh Fahimi-Kashani, M Reza Hormozi-Nezhad
There is a growing interest in developing high-performance sensors monitoring fungicides, due to their broadly usage and their adverse effects on humans and wildlife. In the present study, a colorimetric probe has been proposed for detection of prothioconazole based on aggregation of unmodified silver nanoparticles (AgNPs). Under optimized condition, linear relationships between the concentration of prothioconazole and the absorbance ratio of A500/A395 were found over the range of 0.01μg·mL(-1) to 0.4μg·mL(-1) with quantification limit as low as 1...
June 28, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28680554/characterization-and-antimicrobial-efficacy-of-portland-cement-impregnated-with-silver-nanoparticles
#8
Ki Young Nam
PURPOSE: This study investigated the effects of silver nanoparticle (SN) loading into hydraulic calcium silicate-based Portland cement on its mechanical, antibacterial behavior and biocompatibility as a novel dental bone substitute. MATERIALS AND METHODS: Chemically reduced colloidal SN were combined with Portland cement (PC) by the concentrations of 0 (control), 1.0, 3.0, and 5.0 wt%. The physico-mechanical properties of silver-Portland cement nanocomposites (SPNC) were investigated through X-ray diffraction (XRD), setting time, compressive strength, solubility, and silver ion elution...
June 2017: Journal of Advanced Prosthodontics
https://www.readbyqxmd.com/read/28680432/differential-response-of-floating-and-submerged-leaves-of-longleaf-pondweed-to-silver-ions
#9
Nisha Shabnam, P Sharmila, Govindjee, Hyunook Kim, P Pardha-Saradhi
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 Ag(0) and Ag2O...
2017: Frontiers in Plant Science
https://www.readbyqxmd.com/read/28669185/supramolecular-low-molecular-weight-hydrogelator-stabilization-of-sers-active-aggregated-nanoparticles-for-solution-and-gas-sensing
#10
Tjalling R Canrinus, Wendy W Y Lee, Ben L Feringa, Steven E J Bell, Wesley R Browne
The potential of surface-enhanced Raman scattering (SERS) spectroscopy in both laboratory and field analyses depends on the reliable formation of so-called SERS hot spots, such as those formed during gold or silver nanoparticle aggregation. Unfortunately such aggregates are not stable in solution because they typically grow until they precipitate. Here we describe the use of low-molecular-weight hydrogels formed through pH-triggered self-assembly that occurs at a rate that well matches the rates of aggregation of Au or Ag colloids, allowing them to be trapped at the SERS-active point in the aggregation process...
July 11, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28667385/potential-application-of-sers-for-arsenic-speciation-in-biological-matrices
#11
Mingwei Yang, Shannon Matulis, Lawrence H Boise, Anthony J McGoron, Yong Cai
Speciation of arsenic is usually carried out using chromatography-based methods coupled with spectroscopic determination; however, the inevitable procedures involving sample preparation and separation could potentially alter the integrity of the arsenic metabolites present in biological samples. Surface-enhanced Raman spectroscopy (SERS) could be a promising alternative for providing a reliable arsenic analysis under the influence of a cellular matrix. A method for arsenic speciation using SERS in cellular matrix was developed in this study and four arsenicals were selected, including arsenite (As(III)), arsenate (As(V)), monomethylarsonic acid (MMA(V)) and dimethylarsinic acid (DMA(V))...
June 30, 2017: Analytical and Bioanalytical Chemistry
https://www.readbyqxmd.com/read/28654267/ternary-silver-halide-nanocrystals
#12
Sasitha C Abeyweera, Kowsalya D Rasamani, Yugang Sun
Nanocrystalline silver halides (AgX) such as AgCl, AgBr, and AgI, a class of semiconductor materials with characteristics of both direct and indirect band gaps, represent the most crucial components in traditional photographic processing. The nanocrystal surfaces provide sensitivity specks that can turn into metallic silver, forming an invisible latent image, upon exposure to light. The photographic processing implies that the AgX nanoparticles possess unique properties. First, pristine AgX nanoparticles absorb light only at low efficiency to convert surface AgX into tiny clusters of silver atoms...
June 27, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28650591/the-silver-lining-towards-the-responsible-and-limited-usage-of-silver
#13
REVIEW
Kshipra Naik, Meenal Kowshik
Silver has attracted a lot of attention as a powerful, broad spectrum and natural antimicrobial agent since the ancient times because of its non-toxic nature to the human body at low concentrations. It has been used in treatment of various infections and ulcers, storage of water, and prevention of bacterial growth on the surfaces and within materials. However there are numerous medical and health benefits of colloidal or nano silver apart from its microbicidal ability which as yet have not been fully embraced by the medical community...
June 26, 2017: Journal of Applied Microbiology
https://www.readbyqxmd.com/read/28649029/determination-of-chemical-oxygen-demand-cod-using-an-alternative-wet-chemical-method-free-of-mercury-and-dichromate
#14
Marit Kolb, Müfit Bahadir, Burkhard Teichgräber
Worldwide, the standard methods for the determination of the important wastewater parameter chemical oxygen demand (COD) are still based on the use of the hazardous chemicals, mercury sulfate and chromium(VI). However, due to their properties they are meanwhile classified as "priority pollutants" and shall be phased out or banned in the frame of REACH (current European Chemical Law: Registration, Evaluation, Authorization and restriction of Chemicals) by the European Union. Hence, a new wet-chemical method free of mercury and chromium(VI) was developed...
June 13, 2017: Water Research
https://www.readbyqxmd.com/read/28648060/synthesis-and-spectroscopy-of-silver-doped-pbse-quantum-dots
#15
Daniel M Kroupa, Barbara K Hughes, Elisa M Miller, David T Moore, Nicholas C Anderson, Boris D Chernomordik, Arthur J Nozik, Matthew C Beard
Electronic impurity doping of bulk semiconductors is an essential component of semiconductor science and technology. Yet there are only a handful of studies demonstrating control of electronic impurities in semiconductor nanocrystals. Here, we studied electronic impurity doping of colloidal PbSe quantum dots (QDs) using a postsynthetic cation exchange reaction in which Pb is exchanged for Ag. We found that varying the concentration of dopants exposed to the as-synthesized PbSe QDs controls the extent of exchange...
July 24, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28646437/cytotoxic-and-genotoxic-effects-of-silver-nanoparticle-carboxymethyl-cellulose-on-allium-cepa
#16
Aline A Becaro, Maria Célia Siqueira, Fernanda C Puti, Marcia Regina de Moura, Daniel S Correa, José Manoel Marconcini, Luiz H C Mattoso, Marcos David Ferreira
Several mutagenic agents may be present in substances released in the environment, which may cause serious environmental impacts. Among these substances, there is a special concern regarding the widespread use of silver nanoparticles (AgNP) in several products due to their widely known bactericidal properties, including in the medical field and the food industry (e.g., active packaging). The assessment of the effects of AgNP released in the environment, having different concentrations, sizes, and being associated or not to other types of materials, including polymers, is therefore essential...
July 2017: Environmental Monitoring and Assessment
https://www.readbyqxmd.com/read/28646435/eco-friendly-synthesis-of-silver-nanoparticles-using-green-algae-caulerpa-serrulata-reaction-optimization-catalytic-and-antibacterial-activities
#17
Eman F Aboelfetoh, Rania A El-Shenody, Mohamed M Ghobara
Stable colloidal silver nanoparticles (AgNPs) were synthesized using Caulerpa serrulata (green marine algae) aqueous extract as an efficient reducing and stabilizing agent. This method is considered to be a sustainable alternate to the more complicated chemical procedures. To achieve the optimization synthesis of AgNPs, several effects such as extract concentration, contact time, pH values, and temperature were examined. The synthesized AgNPs were characterized by UV-Vis spectroscopy, FT-IR, XRD, and HR-TEM...
July 2017: Environmental Monitoring and Assessment
https://www.readbyqxmd.com/read/28634713/characterization-and-in-vitro-antibacterial-activity-of-saponin-conjugated-silver-nanoparticles-against-bacteria-that-cause-burn-wound-infection
#18
Anbarasan Muniyan, Kalaiselvi Ravi, Udayamathi Mohan, Rajasekar Panchamoorthy
Saponins are glycosides, which destabilize the membrane by altering the membrane permeability. Thus, the present study was aimed to fabricate the silver nanoparticles (AgNPs) using fenugreek derived saponin (SN) against multi-drug resistant bacteria. This study has optimized the concentration of SN (240 mg/mL) for the synthesis of an effective AgNPs against the test organism Escherichia coli. The SN reduced AgNPs produced a reddish-brown colour and displayed UV absorption at 416 nm. The bio-reducing efficiency of SN (62...
July 2017: World Journal of Microbiology & Biotechnology
https://www.readbyqxmd.com/read/28633660/a-re-assessment-of-the-safety-of-silver-in-household-water-treatment-rapid-systematic-review-of-mammalian-in-vivo-genotoxicity-studies
#19
REVIEW
Lorna Fewtrell, Batsirai Majuru, Paul R Hunter
BACKGROUND: Despite poor evidence of their effectiveness, colloidal silver and silver nanoparticles are increasingly being promoted for treating potentially contaminated drinking water in low income countries. Recently, however, concerns have been raised about the possible genotoxicity of particulate silver. OBJECTIVES: The goal of this paper was to review the published mammalian in vivo genotoxicity studies using silver micro and nanoparticles. METHODS: SCOPUS and Medline were searched using the following search string: ("DNA damage" OR genotox* OR Cytotox* OR Embryotox*) AND (silver OR AgNP)...
June 20, 2017: Environmental Health: a Global Access Science Source
https://www.readbyqxmd.com/read/28628747/laser-ablation-of-silver-in-liquid-organic-monomer-influence-of-experimental-parameters-on-the-synthesized-silver-nanoparticles-graphite-colloids
#20
Maxime Delmée, Grégory Mertz, Julien Bardon, Adeline Marguier, Lydie Ploux, Vincent Roucoules, David Ruch
During the past decade, synthesizing silver nanoparticles (Ag NPs) by liquid phase-pulsed laser ablation (LP-PLA) has attracted a lot of attention. Basically, this technique allows producing various metallic nanoparticles with controlled size, shape, composition, or surroundings in several liquids (i.e., water, ethanol, acetone, toluene, and so forth). Recently, such processes have been studied in liquid organic monomer such as methyl methacrylate (MMA). However, the influence of the laser parameters on the materials synthesized in such reactive liquid and their features were not fully investigated so far...
July 3, 2017: Journal of Physical Chemistry. B
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