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Colloidal silver

Michael J Walsh, Wenming Tong, Hadas Katz-Boon, Paul Mulvaney, Joanne Etheridge, Alison M Funston
The phenomenon of symmetry breaking-in which the order of symmetry of a system is reduced despite manifest higher-order symmetry in the underlying fundamental laws-is pervasive throughout science and nature, playing a critical role in fields ranging from particle physics and quantum theory to cosmology and general relativity. For the growth of crystals, symmetry breaking is the crucial step required to generate a macroscopic shape that has fewer symmetry elements than the unit cell and/or seed crystal from which it grew...
November 16, 2017: Accounts of Chemical Research
Daniele Lantagne, Justine Rayner, Anjuliee Mittelman, Kurt Pennell
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...
November 13, 2017: Environmental Health: a Global Access Science Source
Hyun Chul Park, Isnaeni, Suhyun Gong, Yong-Hoon Cho
Enhancing the fluorescence intensity of colloidal quantum dots (QDs) in case of color-conversion type QD light-emitting devices (LEDs) is very significant due to the large loss of QDs and their quantum yields during fabrication processes, such as patterning and spin-coating, and can therefore improve cost-effectiveness. Understanding the enhancement process is crucial for the design of metallic nanostructure substrates for enhancing the fluorescence of colloidal QDs. In this work, improved color conversion of colloidal green and red QDs coupled with aluminum (Al) and silver (Ag) nanodisk (ND) arrays designed by in-depth systematic finite-difference time domain simulations of excitation, spontaneous emission, and quantum efficiency enhancement is reported...
November 9, 2017: Small
Muhammad Ovais, Akhtar Nadhman, Ali Talha Khalil, Abida Raza, Fazli Khuda, Muhammad Farhan Sohail, Nazar Ul Islam, Hafiz Shoaib Sarwar, Gul Shahnaz, Irshad Ahmad, Muthupandian Saravanan, Zabta Khan Shinwari
Many recent key innovations in nanotechnology have greatly fascinated scientists to explore new avenues in treatment and diagnosis of emerging diseases. Due to extensive utilization of metallic nanoparticles (NPs) in diverse biomedical applications, scientists are looking forward to green synthesis of NPs as safer, simple, fast, and low-cost method over chemical and physical methods. Due to enriched phytochemistry, no need for maintenance and ready availability, plants are preferred for green synthesis of silver (AgNPs) and gold NPs (AuNPs)...
November 7, 2017: Nanomedicine
Jörg Wissler, Martin Wehmeyer, Sandra Bäcker, Shirley K Knauer, Sebastian Schlücker
Many applications of nano- and microparticles require molecular functionalization. Assessing the heterogeneity of a colloidal sample in terms of its molecular functionalization is highly desirable, but not accessible by conventional ensemble experiments. Retrieving this information necessitates single-particle experiments which simultaneously detect both functionalized and non-functionalized particles via two separate imaging channels. In this contribution, we present an optical setup for performing correlative single-particle imaging using laser light-sheet illumination: the first detection channel records elastic light scattering (Rayleigh/Mie), while the second channel detects inelastic light scattering (Raman) or fluorescence...
November 7, 2017: Analytical Chemistry
Laura-Jayne A Ellis, Mohammed Baalousha, Eugenia Valsami-Jones, Jamie R Lead
Understanding the environmental behaviour of nanoparticles (NPs) after release into aquatic systems is essential to predict the environmental implications of nanotechnology. Silver nanoparticles (AgNPs) represent a major class of engineered NPs with a significant potential for environmental impact. Therefore, investigating their transformations in natural waters will help predict their long term environmental fate and behaviour. AgNPs were characterized in natural lake water collected seasonally from the same freshwater source, using column microcosms to assess their behaviour and transport at different depths...
October 23, 2017: Chemosphere
Ji Su Park, Eun-Young Ahn, Youmie Park
Mangosteen (Garcinia mangostana) pericarp waste extract was used to synthesize gold and silver nanoparticles by a green strategy. The extract was both a reducing and stabilizing agent during synthesis. Phytochemical screening of the extract was conducted to obtain information regarding the presence/absence of primary and secondary metabolites in the extract. The in vitro antioxidant activity results demonstrated that the extract had excellent antioxidant activity, which was comparable to a standard (butylated hydroxy toluene)...
2017: International Journal of Nanomedicine
Xu Chen, Wen Xu, Yandong Jiang, Gencai Pan, Donglei Zhou, Jinyang Zhu, He Wang, Cong Chen, Dongyu Li, Hongwei Song
Fabrication of near-infrared light-triggered photoelectrochemical (PEC) sensors based on the upconversion nanophosphors (UCNPs) is a novel approach, which exhibits the advantages of low background signal and non-damage to the biological substance as well as high sensitivity and improved electric detection in PEC sensors. Herein we demonstrate the preparation of novel and high-quality ZnO inverse opal photonic crystals (IOPCs)/Ag/NaYF4:Yb,Tm hybrid films by different advanced film techniques, including colloidal self-assembling, vapor phase deposition and pulsed laser deposition and its application to sensitive detection of alpha-fetoprotein (AFP)...
November 2, 2017: Nanoscale
Albert S Reyna, Emeric Bergmann, Pierre-François Brevet, Cid B de Araújo
We report a study of the nonlinear birefringence induced in a metal-dielectric nanocomposite due to the contributions of third- and fifth-order optical nonlinearities. A theoretical model describing the evolution of the light polarization state of a confined laser beam propagating through the nonlinear medium is developed with basis on a pair of coupled dissipative cubic-quintic nonlinear differential equations related to the two orthogonal polarizations of the optical field. As a proof-of-principle experiment we demonstrate the control of the light beam polarization in a silver-nanocolloid by changing the silver nanoparticles volume fraction, f, and the light intensity...
September 4, 2017: Optics Express
Jun Hou, Mingzhi Zhang, Peifang Wang, Chao Wang, Lingzhan Miao, Yi Xu, Guoxiang You, Bowen Lv, Yangyang Yang, Zhilin Liu
This study investigated the transport and long-term release of stabilized poly vinylpyrrolidone-coated silver nanoparticles (PVP-AgNPs) in a quartz sand column with various sand grain sizes (0.3-0.5 μm, 0.5-1.0 μm, 1.0-2.0 μm), input concentrations of PVP-AgNP solution (1, 5, 15, 25 mg/L), and flow rates corresponding to a filter velocities (1.0, 1.5, 2.0, 2.5 mL/min-0.14, 0.21, 0.28, 0.35 cm/min) by determining breakthrough curves, retention profiles, and long-term release curves. Breakthrough curves and retention profiles were simulated by a mathematical model based on the advection dispersion equation coupled with second-order kinetics...
October 9, 2017: Water Research
Sara Skoglund, Eva Blomberg, Inger Odnevall Wallinder, Isabelle Grillo, Jan Skov Pedersen, L Magnus Bergström
The structural behavior in aqueous mixtures of negatively charged silver nanoparticles (Ag NPs) together with the cationic surfactants cetyltrimethylammonium bromide (CTAB) and dodecyltrimethylammonium chloride (DTAC), respectively, has been investigated using SANS and SAXS. From our SANS data analysis we are able to conclude that the surfactants self-assemble into micellar clusters surrounding the Ag NPs. We are able to quantify our results by means of fitting experimental SANS data with a model based on cluster formation of micelles with very good agreement...
October 25, 2017: Physical Chemistry Chemical Physics: PCCP
Elumalai Satheeshkumar, Jyisy Yang, Venkatesan Srinivasadesikan, Ming-Chang Lin
In this work, a simple method was developed to simultaneously fabricate silver nanoparticles (AgNPs) and modify their surfaces with recognition functional groups for colorimetric detection of Cu(2+) ions. To prepare the AgNPs with proper functional group on their surface for detection of Cu(2+) ions, photochemical reaction was employed and a photoactive species of tyrosine (Tyr) was used to trigger the photoreduction of AgNPs, while the oxidized Tyr (Tyr(Ox)) was used to functionalize the AgNPs surface at the same time...
2017: Analytical Sciences: the International Journal of the Japan Society for Analytical Chemistry
Matias Pasquali, Tommaso Serchi, Sebastien Planchon, Jenny Renaut
The two-dimensional difference gel electrophoresis method is a valuable approach for proteomics. The method, using cyanine fluorescent dyes, allows the co-migration of multiple protein samples in the same gel and their simultaneous detection, thus reducing experimental and analytical time. 2D-DIGE, compared to traditional post-staining 2D-PAGE protocols (e.g., colloidal Coomassie or silver nitrate), provides faster and more reliable gel matching, limiting the impact of gel to gel variation, and allows also a good dynamic range for quantitative comparisons...
2017: Methods in Molecular Biology
Patrycja Giesz, Ewelina Mackiewicz, Jarosław Grobelny, Grzegorz Celichowski, Małgorzata Cieślak
A study on the hybrid functionalization of cotton and viscose fabrics using silver nanowires (AgNWs) colloid and titanium dioxide (TiO2) sol prepared in sol-gel technique was carried out. The microwave treatment was applied to change amorphous form of TiO2 to anatase. The photocatalytic activity of both cellulose fabrics was evaluated by decomposition of nicotine using new method on the basis of infrared spectroscopy. The AgNWs/TiO2 modification caused 3 and 4 times (cotton fabric) and 1.8 and 1.5 (viscose fabric) faster decomposition of nicotine under respectively UV and VIS light than for unmodified fabrics...
December 1, 2017: Carbohydrate Polymers
Yasutaka Kitahama, Hiroaki Hayashi, Tamitake Itoh, Yukihiro Ozaki
Surface-enhanced hyper-Raman scattering (SEHRS) spectra were obtained at desired positions on yeast by focusing a continuous wave near-infrared laser beam while silver nanoparticles (AgNPs) were simultaneously optically trapped. However, the optically trapped colloidal AgNP suspension bubbled up at the focusing point, preventing spectral measurement. In the case of optically trapped AgNPs functionalized with 4-mercaptobenzoic acid (p-MBA), surface-enhanced hyper-Rayleigh scattering was considerably strong, indicating the suppression of the photothermal conversion to form the bubble...
September 27, 2017: Analyst
Stephan J P Kress, Jian Cui, Patrik Rohner, David K Kim, Felipe V Antolinez, Karl-Augustin Zaininger, Sriharsha V Jayanti, Patrizia Richner, Kevin M McPeak, Dimos Poulikakos, David J Norris
Colloidal quantum dots are robust, efficient, and tunable emitters now used in lighting, displays, and lasers. Consequently, when the spaser-a laser-like source of high-intensity, narrow-band surface plasmons-was first proposed, quantum dots were specified as the ideal plasmonic gain medium for overcoming the significant intrinsic losses of plasmons. Many subsequent spasers, however, have required a single material to simultaneously provide gain and define the plasmonic cavity, a design unable to accommodate quantum dots and other colloidal nanomaterials...
September 2017: Science Advances
Sukwoo Jang, Kyungtae Kim, Jonghyuk Jeon, Donghwi Kang, Byeong-Hyeok Sohn
Supracolloidal chains of diblock copolymer micelles were functionalized with gold and silver nanoparticles (NPs). Both NPs were independently synthesized in situ in the core of spherical micelles which were then converted to patchy micelles. With these patchy micelles as colloidal monomers, supracolloidal chains were polymerized by combining the patches of neighboring micelles. Since all micelles contained NPs, NPs were incorporated in every repeat unit of chains. In addition, a single gold NP was synthesized in the micellar core in contrast to several silver NPs so that we differentiated the chains with Au NPs from those with Ag NPs by the number of NPs in the repeat unit as well as by plasmonic bands in UV-Vis spectra...
October 4, 2017: Soft Matter
Adam Lanzarotta, Lisa Lorenz, JaCinta S Batson, Cheryl Flurer
A simple, fast, sensitive and effective pass/fail field-friendly method has been developed for detecting sildenafil in suspect Viagra and unapproved tablets using handheld Raman spectrometers and silver colloids. The method involves dissolving a portion of a tablet in water followed by filtration and addition of silver colloids, resulting in a solution that can be measured directly through a glass vial. Over one hundred counterfeit Viagra and unapproved tablets were examined on three different devices during the method development phase of the study...
September 8, 2017: Journal of Pharmaceutical and Biomedical Analysis
Slađana Davidović, Vesna Lazić, Ivana Vukoje, Jelena Papan, S Phillip Anhrenkiel, Suzana Dimitrijević, Jovan M Nedeljković
A simple, fast and non-costly method for selective cysteine (Cys) detection, based on optical changes of silver colloids, is developed. For that purpose, stable colloids consisting of silver nanoparticles (Ag NPs) coated with polysaccharide dextran (Dex), isolated from bacterium species Leuconostoc mesenteroides T3, were prepared. The synthesized samples were thoroughly characterized including absorption and FTIR spectroscopy, as well as transmission electron microscopy and X-ray diffraction analysis. The silver colloids display high sensitivity and selectivity towards Cys detection in aqueous solutions...
September 12, 2017: Colloids and Surfaces. B, Biointerfaces
Birgütay Şahin, Enes Demir, Ayşenur Aygün, Hülya Gündüz, Fatih Şen
In this study, we aimed to investigate whether the combination therapy of pomegranate extract and silver nanoparticle is effective on MCF-7 cell culture. The pomegranate extract was mixed and incubated with silver nitrate for the microwave assisted green synthesized of silver nanoparticle. Obtained nanoparticles were investigated using X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), UV-vis, Field Emission Scanning Electron Microscopy (FESEM), and Transmission Electron Microscopy (TEM) methods The spectroscopic and morphological studies of the monodisperse Ag NPs which have particle size of 15...
September 18, 2017: Journal of Biotechnology
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