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Colloidal silver

Maja Levak, Petra Burić, Maja Dutour Sikirić, Darija Domazet Jurašin, Nevenka Mikac, Niko Bačić, Roland Drexel, Florian Meier, Željko Jakšić, Daniel Mark Lyons
In parallel with the growing use of nanoparticle-containing products, their release into the environment over the coming years is expected to increase significantly. With many large population centers located in near-coastal areas, and increasing evidence that various nanoparticles may be toxic to a range of organisms, biota in estuarine and coastal waters may be particularly vulnerable. While size effects may be important in cases, silver nanoparticles have been found to be toxic in large part due to their release of silver ions...
January 11, 2017: Environmental Science & Technology
Youji Shimazaki, Rino Miyatsuka
Delipidation in biological samples is important for some diagnostic tests and protein analyses. Lipids in the samples can be hydrolyzed by native esterases (ESs) within gel capsules after ES, and ES-antibody complexes are specifically trapped, extracted, and separated. Acrylamide and agarose gel capsules containing complexes of ES antibody were produced after the complexes were extracted using protein A-immobilized membranes, separated by non-denaturing electrophoresis, and stained by colloidal silver using glucose as a reductant...
January 9, 2017: Applied Biochemistry and Biotechnology
Alexey Treshchalov, Heiki Erikson, Laurits Puust, Sergey Tsarenko, Rando Saar, Alexander Vanetsev, Kaido Tammeveski, Ilmo Sildos
In this work we demonstrated the potential of the He+5% H2+1% N2 plasma jet treatment for the synthesis of surfactant-free silver nanoparticles (Ag NPs) with narrow size distribution. The obtained colloidal solutions of electrostatically stabilized Ag NPs do not show any agglomeration for several months. Apart from an atomic thin oxide layer and the relatively weakly bound OH(-) ions, the surface of Ag NPs can be considered as stabilizer-free. The surface charge (characterized by the zeta potential) of Ag NPs in solution was measured by electrophoretic light scattering technique...
December 24, 2016: Journal of Colloid and Interface Science
Snežana Miljanić, Marina Ratkaj, Marija Matković, Ivo Piantanida, Paola Gratteri, Carla Bazzicalupi
G-Quadruplex (G4) structures of a human telomeric 24-mer (5'-TTAGGGTTAGGGTTAGGGTTAGGG-3') sequence (Tel24) stabilized by sodium and potassium ions have been assessed using surface-enhanced Raman scattering (SERS) spectroscopy. The distinctive SERS spectra of Tel24 in the presence of 100 mM Na(+) and 100 mM K(+) were obtained and the SERS bands characteristic of the antiparallel basket-type and the mixed hybrid (3+1) structures, respectively, were identified and assigned. The influence of the SERS - active substrate on the scattering enhancement was studied using citrate- and chloride-covered silver nanoparticles, in the absence and presence of the aggregating agent (0...
January 4, 2017: Analytical and Bioanalytical Chemistry
Hyun-A Kim, Byung-Tae Lee, So-Young Na, Kyoung-Woong Kim, James F Ranville, Soon-Oh Kim, Eunhye Jo, Ig-Chun Eom
The single particle-inductively coupled plasma-mass spectrometry was applied to characterize the aggregates of AgNPs. was applied to characterize the aggregates of AgNPs. Two sizes of citrate-AgNPs and PVP-AgNPs were used at relatively high and predicted environmental concentrations under various ionic strengths. Citrate-AgNP aggregated with increases in the ionic strength, whereas PVP-AgNPs were sterically stable. The critical coagulation concentrations were 85 mM and 100 mM NaNO3 for 60 nm and 100 nm citrate-AgNPs at 2 mg L(-1) as total Ag obtained by dynamic light scattering (DLS)...
December 19, 2016: Chemosphere
Danaja Štular, Ivan Jerman, Iztok Naglič, Barbara Simončič, Brigita Tomšič
Silver nanoparticles were embedded into a temperature- and pH-responsive microgel based on poly-(N-isopropylacrylamide) and chitosan (PNCS) before or after its application to cotton fabric to create a smart stimuli-responsive textile with simultaneous moisture management and controlled antimicrobial activities. Two different methods of silver embedment into the PNCS microgel using two different forms of silver nanoparticles were studied, i.e., in-situ synthesis of AgCl nanocrystals into PNCS microgel particles that had previously been applied to cotton fabric, as well as the direct incorporation of colloidal silver into the microgel suspension prior to its deposition on cellulose fibres...
March 1, 2017: Carbohydrate Polymers
Jamila Djafari, Catarina Marinho, Tiago Santos, Gilberto Igrejas, Carmen Torres, José Luis Capelo, Patricia Poeta, Carlos Lodeiro, Javier Fernández-Lodeiro
The Front Cover picture shows new silver (Ag) and gold (Au) nanoparticle-based tetracycline (TC) nanocomposites (AuNPs@TC and AgNPs@TC). A new synthetic methodology for the preparation of water-soluble Au and Ag nanoparticles, using the antibiotic TC as co-reducing and stabilizing agent, is reported. Both colloids exhibit high water stability, with an average size of 15±5 and 25±10 nm, respectively. Both composites are tested against TC-resistant bacteria, presenting an increasing antibacterial effect in the case of AgNPs@TC...
June 2016: ChemistryOpen
Alex J Bertuccio, Robert D Tilton
Silver nanoparticles (AgNPs) released from consumer products may enter the environment and possibly harm microbial communities. Prior research showed that surface-adherent AgNPs inhibit bacterial surface colonization, a precursor to biofilm formation, only when planktonic bacterial inoculum concentrations are less than a threshold level ( Wirth and co-workers, J. Colloid Interface Sci. 2016 , 467 , 17 - 27 ). This inoculum effect is due to a decrease in free silver ion concentration associated with sublethal binding to bacteria...
January 9, 2017: Environmental Science & Technology
B Rezaei, M Shahshahanipour, Ali A Ensafi
In the present research, a sensitive biosensing method was proposed for the detection of trace amounts of ascorbic acid (AA). Herein, colloidal silver nanoparticles (SNPs) were successfully in-situ produced by chemical reduction of silver ion in the presence of AA, as a reducing agent. The one-pot in-situ produced silver nanoparticles were characterized by UV-vis, dynamic light scattering (DLS), zeta potential and transmission electron microscopic (TEM). SNPs act as a strong fluorescence quencher for the CdTe quantum dots via an inner filter effect (IFE)...
February 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
Paolo Matteini, Maximilien Cottat, Francesco Tavanti, Elizaveta Panfilova, Mario Scuderi, Giuseppe Nicotra, Maria Cristina Menziani, Nikolai Khlebtsov, Marella de Angelis, Roberto Pini
Strategies for protein detection via surface-enhanced Raman spectroscopy (SERS) currently exploit the formation of randomly generated hot spots at the interfaces of metal colloidal nanoparticles, which are clustered together by intrusive chemical or physical processes in the presence of the target biomolecule. We propose a different approach based on selective and quantitative gathering of protein molecules at regular hot spots generated on the corners of individual silver nanocubes in aqueous medium at physiological pH...
December 20, 2016: ACS Nano
Jamila Djafari, Catarina Marinho, Tiago Santos, Gilberto Igrejas, Carmen Torres, José Luis Capelo, Patricia Poeta, Carlos Lodeiro, Javier Fernández-Lodeiro
A new synthetic methodology of water-soluble gold and silver nanoparticles (AuNPs@TC and AgNPs@TC), using the antibiotic tetracycline (TC) as co-reducing and stabilizing agent, is reported. Both colloids exhibit high water stability. The average sizes obtained were 25±10 and 15±5 nm, respectively. Both composites were tested against TC-resistant bacteria, presenting an increasing antibacterial effect in the case of AgNPs@TC. The sensing towards metal ions was also explored. An interesting and reversible affinity of AuNPs@TC towards Al(III) cations in an aqueous system was also observed...
June 2016: ChemistryOpen
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)...
January 20, 2017: 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...
December 7, 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...
January 15, 2017: European Journal of Pharmaceutical Sciences
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