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Colloidal silver

Chao-Shun Lai, Yi-Chen Chen, Hsiao-Fang Wang, Hsin-Chia Ho, Rong-Ming Ho, De-Hao Tsai
We report a systematic study of the controlled gas-phase synthesis of silver-silica hybrid nanostructures (Ag-SiO2 NP) using the concept of evaporation-induced self-assembly. The approach includes the use of a direct gas-phase electrophoresis for size classification and in situ characterization of mobility size. Transmission electron microscopy and ultraviolet-visible light spectroscopy were employed complementarily to determine the morphology and surface plasmon resonance of Ag-SiO2 NP. Results show that two types of Ag-SiO2 NPs were successfully synthesized: (1) AgNPs decorated on a SiO2-NP (Ag-T-SiO2 NP), and (2) AgNPs doped in a cluster of SiO2-NPs (Ag-C-SiO2 NP)...
December 8, 2016: Nanotechnology
María Soledad Morales-Covarrubias, Noemí García-Aguilar, María Del Bolan-Mejía, Ana Carmela Puello-Cruz
In shrimp aquaculture, reduction in the use of synthetic antibiotics is a priority due to the high incidence of resistant bacteria (Vibrio) in the white shrimp Litopenaeus vannamei. An increasing number of studies show bactericidal activity of natural treatments in aquaculture. The effectiveness of neem (Azadirachta indica) and oregano (Lippia berlandieri) aqueous extracts and colloidal silver against V. parahaemolyticus were evaluated in low salinity shrimp culture. Results show that aqueous extracts of oregano and neem each present a minimum inhibitory concentration (MIC) of 62...
November 22, 2016: Diseases of Aquatic Organisms
Tikam Chand Dakal, Anu Kumar, Rita S Majumdar, Vinod Yadav
Multidrug resistance of the pathogenic microorganisms to the antimicrobial drugs has become a major impediment toward successful diagnosis and management of infectious diseases. Recent advancements in nanotechnology-based medicines have opened new horizons for combating multidrug resistance in microorganisms. In particular, the use of silver nanoparticles (AgNPs) as a potent antibacterial agent has received much attention. The most critical physico-chemical parameters that affect the antimicrobial potential of AgNPs include size, shape, surface charge, concentration and colloidal state...
2016: Frontiers in Microbiology
Xavierravi Baskaran, Antony Varuvel Geo Vigila, Thangaraj Parimelazhagan, Doulathabad Muralidhara-Rao, Shouzhou Zhang
The objective of the study was to characterize silver nanoparticles (Ag-NPs) and their bioactivities in early tracheophytes (Pteridophyta). Aqueous leaf extract of a critically endangered fern, Pteris tripartita Sw., was used for one-step green synthesis of Ag-NPs. The biosynthesized Ag-NPs were characterized using ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and high-resolution transmission electron microscopy...
2016: International Journal of Nanomedicine
Feike J Leij, Scott A Bradford, Antonella Sciortino
Elucidating and quantifying the transport of industrial nanoparticles (e.g. silver, carbon nanotubes, and graphene oxide) and other colloid-size particles such as viruses and bacteria is important to safeguard and manage the quality of the subsurface environment. Analytic solutions were derived for aqueous and solid phase colloid concentrations in a porous medium where colloids were subject to advective transport and reversible time and/or depth-dependent retention. Time-dependent blocking and ripening retention were described using a Langmuir-type equation with a rate coefficient that respectively decreased and increased linearly with the retained concentration...
December 2016: Journal of Contaminant Hydrology
A Resano-Garcia, S Champmartin, Y Battie, A Koch, A En Naciri, A Ambari, N Chaoui
By irradiating a cylindrical silver target rotated at a high-speed within the range 300-2400 rpm (lateral speed 0.16-1.25 m s(-1)) in pure water, we prepare ligand-free Ag nanoparticles (NPs) with a size of 4 ± 2 nm which are likely to be primary particles. Usually, the generation of NPs showing such a small size requires either a laser post-treatment and/or chemical additives. As the rotation rate of the target is increased, calculated 3D flow patterns revealed different hydrodynamic regimes which clearly influence the ablation rate and repeatability of the process as well as the colloidal properties...
November 24, 2016: Physical Chemistry Chemical Physics: PCCP
Israa Haidar, Georges Lévi, Ludovic Mouton, Jean Aubard, Johan Grand, Stéphanie Lau-Truong, Daniel R Neuville, Nordin Félidj, Leïla Boubekeur-Lecaque
The controlled assembly of anisotropic plasmonic nanoparticles (NPs) into highly SERS-active substrates remains particularly challenging for the production of long-term stable NP assemblies in suspension. In this work, we report a simple and efficient strategy to assemble gold nanorods (AuNRs) into dimers. The pH-dependent assembly was triggered using the bifunctional molecular linker BPE (1,2-bis(4-pyridyl)ethylene) and quenched with silver nitrate. The resulting AuNR dimers were encapsulated in mesoporous silica shell and proved to be stable in water for at least 5 months...
November 30, 2016: Physical Chemistry Chemical Physics: PCCP
Jian Wu, Dao Xiang, Ghazal Hajisalem, Fan-Cheng Lin, Jer-Shing Huang, Chun-Hong Kuo, Reuven Gordon
We probe the acoustic vibrations of silver nanoprisms and gold nano-octahedrons in aqueous solution with four-wave mixing. The nonlinear optical response shows two acoustic vibrational modes: an in-plane mode of nanoprisms with vertexial expansion and contraction; an extensional mode of nano-octahedrons with longitudinal expansion and transverse contraction. The particles were also analyzed with electron microscopy and the acoustic resonance frequencies were then calculated by the finite element analysis, showing good agreement with experimental observations...
October 17, 2016: Optics Express
Ines Castangia, Francesca Marongiu, Maria Letizia Manca, Raffaello Pompei, Fabrizio Angius, Andrea Ardu, Anna Maria Fadda, Maria Manconi, Guido Ennas
In the present work, silver nanoparticles were prepared using a totally green procedure combining silver nitrate and an extract of grape pomace as a green source. Additionally, nanoparticles were stabilized using phospholipid and water and/or a mixture of water and propylene glycol (PG). To the best of our knowledge, grape-silver nanoparticle stabilized liposomes or PG-liposomes were formulated, for the first time, combining the residual products of wine-made industry, silver nitrate and phospholipids, avoiding the addition of hazardous substances to human health and the environment, in an easy, scalable and reproducible method...
November 4, 2016: European Journal of Pharmaceutical Sciences
Vera Dugandžić, Izabella Jolan Hidi, Karina Weber, Dana Cialla-May, Jürgen Popp
Herein we report a novel strategy for the in situ synthesis of the silver colloids for LoC-SERS applications. Silver nanoparticles are obtained in a segmented flow based glass microfluidic chip by the reduction of silver ions with hydrazine in ammonium hydroxide solution. Citrate ions are used as protecting agents. The synthesized nanoparticles are characterized by UV-VIS spectroscopy, SEM and TEM imaging. The SERS performance of the in situ synthesized nanoparticles is tested by using adenine as a test analyte right after the colloid synthesis...
November 23, 2016: Analytica Chimica Acta
Hasitha de Alwis Weerasekera, María Jazmín Silvero, Daliane Regis Correa da Silva, Juan C Scaiano
Colloidal stability of nanoparticles in biological media is an important consideration when trying to ensure reliable data interpretation of in vitro and in vivo systems. We have developed a detailed colloidal stability library of newly synthesized gold, silver and gold-core silver-shell plasmonic nanoparticles, stabilized with aspartame, glucosamine and sucralose, in various biologically relevant buffers and bacterial and mammalian cell culture media. The stabilizer selection reflects the preference for molecules that are non-toxic, inexpensive, readily available, water soluble and easy-to-replace if that is the end-user preference...
November 8, 2016: Biomaterials Science
Aaron Goldman, Sandra Harper, David W Speicher
Staining of blot membranes enables the visualization of bound proteins. Proteins are usually transferred to blot membranes by electroblotting, by direct spotting of protein solutions, or by contact blots. Staining allows the efficiency of transfer to the membrane to be monitored. This unit describes protocols for staining proteins after electroblotting from polyacrylamide gels to blot membranes such as polyvinylidene difluoride (PVDF), nitrocellulose, or nylon membranes. The same methods can be used if proteins are directly spotted, either manually or using robotics...
November 1, 2016: Current Protocols in Protein Science
Marialucia Gallorini, Viviana di Giacomo, Valentina Di Valerio, Monica Rapino, Domenico Bosco, Andrea Travan, Mara Di Giulio, Roberta Di Pietro, Sergio Paoletti, Amelia Cataldi, Silvia Sancilio
Silver-based products have been proven to be effective in retarding and preventing bacterial growth since ancient times. In the field of restorative dentistry, the use of silver ions/nanoparticles has been explored to counteract bacterial infections, as silver can destroy bacterial cell walls by reacting with membrane proteins. However, it is also cytotoxic towards eukaryotic cells, which are capable of internalizing nanoparticles. In this work, we investigated the biological effects of Chitlac-nAg, a colloidal system based on a modified chitosan (Chitlac), administered for 24-48 h to a co-culture of primary human gingival fibroblasts and Streptococcus mitis in the presence of saliva, developed to mimic the microenvironment of the oral cavity...
December 2016: Journal of Materials Science. Materials in Medicine
Cheng-Yu Shih, Chengping Wu, Maxim V Shugaev, Leonid V Zhigilei
Laser ablation in liquids is actively used for generation of clean colloidal nanoparticles with unique shapes and functionalities. The fundamental mechanisms of the laser ablation in liquids and the key processes that control the nanoparticle structure, composition, and size distribution, however, are not yet fully understood. In this paper, we report the results of first atomistic simulations of laser ablation of metal targets in liquid environment. A model combining a coarse-grained representation of the liquid environment (parameterized for water), a fully atomistic description of laser interactions with metal targets, and acoustic impedance matching boundary conditions is developed and applied for simulation of laser ablation of a thin silver film deposited on a silica substrate...
October 15, 2016: Journal of Colloid and Interface Science
Yuliang Dong, Weiqing Liu, Yiling Lei, Tingxi Wu, Shiwen Zhang, Yuchen Guo, Yuan Liu, Demeng Chen, Quan Yuan, Yongyue Wang
Oral infectious diseases may lead to bone loss, which makes it difficult to achieve satisfactory restoration. The rise of multidrug resistant bacteria has put forward severe challenges to the use of antibiotics. Silver (Ag) has long been known as a strong antibacterial agent. In clinic, gelatin sponge with colloid silver is used to reduce tooth extraction complication. To investigate how this material affect infected bone defects, methicillin-resistant Staphylococcus aureus (MRSA) infected 3-mm-diameter cranial defects were created in adult female Sprague-Dawley rats...
January 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
Mahmoud A Mahmoud
Colloidal silver nanodisks (AgNDs) are assembled into a monolayer with a coverage density gradient (CDG) on the surface of flat and cylindrical substrates using the Langmuir- Blodgett (LB) technique. Compressing the LB monolayers during transfer to the substrates causes the CDG assembly of the AgNDs. By functionalizing the AgNDs with polyethylene glycol, it is possible to control their order inside the LB monolayer assembly by changing the deposition surface pressure. Well-separated AgNDs, 2D aggregates with different amounts of particles, and highly packed 2D arrays are formed as the deposition surface pressure is increased...
October 11, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Elena P Vetchinkina, Ekaterina A Loshchinina, Ilya R Vodolazov, Viktor F Kursky, Lev A Dykman, Valentina E Nikitina
The work shows the ability of cultured Basidiomycetes of different taxonomic groups-Lentinus edodes, Pleurotus ostreatus, Ganoderma lucidum, and Grifola frondosa-to recover gold, silver, selenium, and silicon, to elemental state with nanoparticles formation. It examines the effect of these metal and metalloid compounds on the parameters of growth and accumulation of biomass; the optimal cultivation conditions and concentrations of the studied ion-containing compounds for recovery of nanoparticles have been identified...
October 7, 2016: Applied Microbiology and Biotechnology
Zhihong Xuan, Mingmin Li, Pengfei Rong, Wei Wang, Yijun Li, Dingbin Liu
Herein, we demonstrate a plasmonic ELISA based on the alkaline phosphatase (ALP)-mediated growth of silver nanoparticles (AgNPs) for the sensitive, rapid, and naked-eye detection of cancer biomarkers in clinical serum samples. This approach was used to measure the low-abundance alpha fetal protein (AFP) in clinical sera, which demonstrates its great capability in the differentiation of cancers and evaluation of therapeutic responses. Impressively, the readout of the plasmonic assay depends on the rapid formation of Ag colloidal solutions with various degrees of yellow color, which can be distinguished by the naked eye, without the need for sophisticated platforms...
October 6, 2016: Nanoscale
Kallayi Nabeela, Reny Thankam Thomas, Jyothi B Nair, Kaustabh Kumar Maiti, Krishna Gopa Kumar Warrier, Saju Pillai
Synthesis of shape-tuned silver (Ag) nanostructures with high plasmon characteristics has drawn significant importance in in-vitro diagnostic applications. Herein, we report a simple aqueous synthetic route using TEMPO-oxidized nanocellulose fibers (T-NCF) and trisodium citrate (TSC) that results in anisotropically grown flower-like Ag nanoconstruct (AgNF). A detailed investigation of the concentration and sequence of the addition of reactants on the formation of these anisotropic Ag structure is presented...
October 6, 2016: ACS Applied Materials & Interfaces
Seda Keleştemur, Mustafa Çulha
Biofilm formation is a defense mechanism for microorganisms to survive under both natural and stress conditions. Clinically relevant microorganisms threaten patient health through biofilm formation on medical devices and implants. It is very important to identify biofilm formation in order to suppress their pathogenic activities in early stages. With the aim for better understanding biofilm formation and possibility of detection, in this study, biofilm formation of clinically important microorganisms, Pseudomonas aeruginosa, Staphylococcus epidermidis, and Candida albicans are monitored with surface-enhanced Raman scattering (SERS)...
October 5, 2016: Applied Spectroscopy
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