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Colloidal silver

Amirmostafa Amirjani, Davoud Haghshenas Fatmehsari
In this work, a rapid and straightforward method was developed for colorimetric determination of ammonia using smartphones. The mechanisms is based on the manipulation of the surface plasmon band of silver nanoparticles (AgNPs) via the formation of Ag (NH3)2(+) complex. This complex decreases the amount of AgNPs in the solution and consequently, the color intensity of the colloidal system decreases. Not only the variation in color intensity of the solution can be tracked by a UV-vis spectrophotometer, but also a smartphone can be employed to monitor the color intensity variation by RGB analysis...
January 1, 2018: Talanta
Brent M DeVetter, Bruce E Bernacki, Wendy D Bennett, Alan Schemer-Kohrn, Kyle J Alvine
Within recent years, the field of plasmonics has exploded as researchers have demonstrated exciting applications related to chemical and optical sensing in combination with new nanofabrication techniques. A plasmon is a quantum of charge density oscillation that lends nanoscale metals such as gold and silver unique optical properties. In particular, gold and silver nanoparticles exhibit localized surface plasmon resonances-collective charge density oscillations on the surface of the nanoparticle-in the visible spectrum...
September 2, 2017: Journal of Visualized Experiments: JoVE
Hyekyoung Choi, Sungwoo Kim, Joseph M Luther, Sang-Wook Kim, Dongwoon Shin, Matthew C Beard, Sohee Jeong
Silver dimetal chalcogenide (Ag-V-VI2) ternary quantum dots (QDs) are emerging lead-free materials for optoelectronic devices due to their NIR band gaps, large absorption coefficients, and superior electronic properties. However, thin film-based devices of the ternary QDs still lag behind due to the lack of understanding of the surface chemistry, compared to that of lead chalcogenide QDs even with the same crystal structure. Herein, we study surface ligand interactions of AgSbS2 QDs synthesized with 1-dodecanethiol used as a stabilizer...
September 7, 2017: Chemistry: a European Journal
Jingyi Feng, Yaxi Hu, Edward Grant, Xiaonan Lu
Thiabendazole, a systemic fungicide used to treat vegetables and fruits during postharvest process, persists as detrimental residue to consumers. We combine a molecularly imprinted polymers (MIPs) with surface enhanced Raman spectroscopy (SERS) to form a novel MISPE-SERS chemosensor and determined thiabendazole in orange juice. Kinetic and static adsorption tests validated the efficient and selective adsorption of thiabendazole using synthesized MIPs via precipitation polymerization. Synthesized MIPs were packed into solid phase extraction (SPE) cartridge to serve as tailor-made sorbents for the separation of thiabendazole in orange juice...
January 15, 2018: Food Chemistry
Virginia Echavarri-Bravo, Lynn Paterson, Thomas J Aspray, Joanne S Porter, Michael K Winson, Mark G J Hartl
Scarce information is available regarding the fate and toxicology of engineered silver nanoparticles (AgNPs) in the marine environment, especially when compared to other environmental compartments. Hence, the antibacterial activity of the NM-300 AgNPs (OECD programme) and a household product containing colloidal AgNPs (Mesosilver) was investigated using marine bacteria, pure cultures and natural mixed populations (microcosm approach). Bacterial susceptibility to AgNPs was species-specific, with Gram negative bacteria being more resistant than the Gram positive species (NM-300 concentration used ranged between 0...
August 22, 2017: Marine Environmental Research
Lionel Chapus, Pierre Aubertin, Suzanne Joiret, Ivan T Lucas, Emmanuel Maisonhaute, Alexa Courty
We present here new substrates for Surface Enhanced Raman Spectroscopy (SERS). The synthesis of colloidal nanoparticles through organometallic route allowed to obtain gold, silver or copper nanoparticles of well-controlled shapes and sizes (between 5 and 12 nm in diameter). The organization of these nanoparticles into large-scale 3D superlattices produces a very large number of "hot spots" at the origin of the signal enhancement. Each superlattice was studied individually in order to correlate its optical and SERS properties to its thickness, to the nanoparticle sizes and to the interparticle distance...
September 1, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Katarzyna Ranoszek-Soliwoda, Ewa Czechowska, Emilia Tomaszewska, Grzegorz Celichowski, Tomasz Kowalczyk, Tomasz Sakowicz, Janusz Szemraj, Jaroslaw Grobelny
In this study we present a method to determine the degree to which catalase (CAT) is adsorbed onto gold nanoparticles (AuNPs) using polyacrylamide gel electrophoresis (PAGE) with silver staining. AuNPs (13nm) were synthesized in water by the chemical reduction method and modified with CAT (AuNPs-CAT). The colloidal stability and NP size before and after the modification were investigated by dynamic light scattering and scanning transmission electron microscopy. Electrophoresis was performed under different conditions (native, with and without SDS, and with and without β-mercaptoethanol) to find the optimal conditions for determining the surface coverage of AuNPs with CAT protein...
August 18, 2017: Colloids and Surfaces. B, Biointerfaces
Dandy Ahamefula Osibe, Nneka Virginia Chiejina, Kazuyoshi Ogawa, Hideki Aoyagi
Biocompatibility and ecotoxicity concerns associated with chemically produced metallic nanoparticles have led to an increasing interest in the development of environmentally benign alternatives for nanoparticle synthesis using biological platforms. Herein, we report the utilization of an extract of seed-derived callus of Catharanthus roseus for the production of stable silver nanoparticles (Ag NPs). The bioreduction of silver ions was evident from UV-Vis spectroscopy results: the absorption maxima were observed at 425 nm, indicative of elemental silver...
August 22, 2017: Artificial Cells, Nanomedicine, and Biotechnology
Xuanwei Ong, Shashank Gupta, Wen-Ya Wu, Sabyasachi Chakrabortty, Yinthai Chan
Here, we describe a protocol that allows for shape-anisotropic cadmium chalcogenide nanocrystals (NCs), such as nanorods (NRs) and tetrapods (TPs), to be covalently and site-specifically linked via their end facets, resulting in polymer-like linear or branched chains. The linking procedure begins with a cation-exchange process in which the end facets of the cadmium chalcogenide NCs are first converted to silver chalcogenide. This is followed by the selective removal of ligands at their surface. This results in cadmium chalcogenide NCs with highly reactive silver chalcogenide end facets that spontaneously fuse upon contact with each other, thereby establishing an interparticle facet-to-facet attachment...
August 10, 2017: Journal of Visualized Experiments: JoVE
Thai Phuong Nguyen, Wei-Chang Chang, Yen-Chih Lai, Ta-Chih Hsiao, De-Hao Tsai
In this work, we develop an aerosol-based, time-resolved ion mobility-coupled mass characterization method to investigate colloidal assembly of graphene oxide (GO)-silver nanoparticle (AgNP) hybrid nanostructure on a quantitative basis. Transmission electron microscopy (TEM) and zeta potential (ZP) analysis were used to provide visual information and elemental-based particle size distributions, respectively. Results clearly show a successful controlled assembly of GO-AgNP by electrostatic-directed heterogeneous aggregation between GO and bovine serum albumin (BSA)-functionalized AgNP under an acidic environment...
August 16, 2017: Analytical and Bioanalytical Chemistry
Tomonari Dotera, Shinichi Bekku, Primož Ziherl
The most striking feature of conventional quasicrystals is their non-traditional symmetry characterized by icosahedral, dodecagonal, decagonal or octagonal axes. The symmetry and the aperiodicity of these materials stem from an irrational ratio of two or more length scales controlling their structure, the best-known examples being the Penrose and the Ammann-Beenker tiling as two-dimensional models related to the golden and the silver mean, respectively. Surprisingly, no other metallic-mean tilings have been discovered so far...
August 14, 2017: Nature Materials
Ling Wu, Gyu Min Kim, Hiroyasu Nishi, Tetsu Tatsuma
Solid-state photovoltaic cells based on plasmon-induced charge separation (PICS) have attracted growing attention during the past decade. However, the power conversion efficiency (PCE) of the previously reported devices, which are generally loaded with dispersed metal nanoparticles as light absorbers, has not been sufficiently high. Here we report simpler plasmonic photovoltaic cells with interconnected Au, Ag, and Cu half-shell arrays deposited on SiO2@TiO2 colloidal crystals, which serve both as a plasmonic light absorber and as a current collector...
August 24, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Kash Anderson, Benjamin Poulter, John Dudgeon, Shu-En Li, Xiang Ma
A novel and highly sensitive nonenzymatic glucose biosensor was developed by nucleating colloidal silver nanoparticles (AgNPs) on MoS₂. The facile fabrication method, high reproducibility (97.5%) and stability indicates a promising capability for large-scale manufacturing. Additionally, the excellent sensitivity (9044.6 μA mM(-1) cm(-2)), low detection limit (0.03 μM), appropriate linear range of 0.1-1000 μM, and high selectivity suggests that this biosensor has a great potential to be applied for noninvasive glucose detection in human body fluids, such as sweat and saliva...
August 5, 2017: Sensors
Maira Berenice Moreno-Trejo, Margarita Sánchez-Domínguez
The synthesis that is described in this study is for the preparation of silver nanoparticles of sizes ranging from 10 nm to 30 nm with a defined shape (globular), confirmed by UV-vis, SEM, STEM and DLS analysis. This simple and favorable one-step modified Tollens reaction does not require any special equipment or other stabilizing or reducing agent except for a solution of purified mesquite gum, and it produces aqueous colloidal dispersions of silver nanoparticles with a stability thatexceeds three months, a relatively narrow size distribution, a low tendency to aggregate and a yield of at least 95% for all cases...
October 4, 2016: Materials
R Sithara, P Selvakumar, C Arun, S Anandan, P Sivashanmugam
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...
November 2017: Journal of Advanced Research
SungJun Park, Hye Hun Park, Young-Seon Ko, Su Jin Lee, The Son Le, Kyoungja Woo, GwangPyo Ko
Silver nanoparticles (AgNPs) have long been considered a powerful disinfectant for controlling pathogenic microorganisms. However, AgNPs might have adverse effects on both human health and our ecosystems due to their potential cytotoxicity and the difficulty in recovering them after their release into the environment. In this study, we characterized the antimicrobial efficacy caused by a novel micrometer-sized magnetic hybrid colloid (MHC) containing 7, 15, or 30nm sized monodispersed AgNPs (AgNP-MHCs), which can be re-collected from the environment using simple procedures, such as a magnet or centrifugation...
December 31, 2017: Science of the Total Environment
Lenore Kubie, Laurie A King, Meghan E Kern, Joseph R Murphy, Subash Kattel, Qian Yang, Joshua T Stecher, William D Rice, Bruce A Parkinson
We report the synthesis of ultrathin silver sulfide (Ag2S) nanoplatelets (NPLs) synthesized via a one-pot method in ethylene glycol with 3-mercaptopropionic acid serving as both the sulfur precursor and the platelet ligand. The colloidally synthesized nanoplatelets are exceptionally thin, with a thickness of only 3.5 ± 0.2 Å and a 1S exciton Bohr diameter to confinement ratio of ∼12.6. The NPL growth is shown to be quantized by layer thickness using absorption and photoluminescence (PL) spectroscopy. Transmission electron microscopy, atomic force microscopy, and X-ray diffraction analyses of the NPLs show that they correspond to the (202) plane of the β-Ag2S structure...
August 22, 2017: ACS Nano
Ali Es-Haghi, Mohammad Mashreghi, Mahere Rezazade Bazaz, Masoud Homayouni-Tabrizi, Majid Darroudi
The aim of this study is to introduce natural-based polymers, chitosan and starch, to design a remedial nanocomposite, comprising of cerium oxide nanoparticles and silver nanoparticles, to investigate their effects in accelerating wound healing and in wound microbial load. Cerium oxide nanoparticles synthesized in starch solution added to the colloidal dispersion of synthesized silver nanoparticles in chitosan to make a three-component nanomaterial. Mice were anaesthetized and two parallel full-thickness round wounds were excised under aseptic conditions with the help of sterile dermal biopsy punch...
August 2017: IET Nanobiotechnology
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
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
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