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Colloidal silver

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
Juan I Paredes, José M Munuera, Silvia Villar-Rodil, Laura Guardia, Miguel Ayán-Varela, Ana Pagán, Salvador D Aznar-Cervantes, José L Cenis, Amelia Martínez-Alonso, Juan M D Tascón
Chemically exfoliated MoS2 (ce-MoS2) has emerged in recent years as an attractive two-dimensional material for use in relevant technological applications, but fully exploiting its potential and versatility will most probably require the deployment of appropriate chemical modification strategies. Here, we demonstrate that extensive covalent functionalization of ce-MoS2 nanosheets with acetic acid groups (∼0.4 groups grafted per MoS2 unit) based on the organoiodide chemistry brings a number of benefits in terms of their processability and functionality...
October 5, 2016: ACS Applied Materials & Interfaces
Nahid Farkhari, Sara Abbasian, Ahmad Moshaii, Maryam Nikkhah
The mechanism of adsorption of single and double stranded DNAs on colloidal gold and silver nanoparticles has been studied by measuring the resistance of the nanoparticles, surrounded by various oligonucleotides, against salt induced aggregation. It is shown that both single and double stranded DNAs can be adsorbed on the metal nanoparticles and the adsorption strength is determined by the interaction between various bases of DNA and the nanoparticles. By changing the salt concentration, the difference between adsorption of various DNA strands on the nanoparticles can be specified...
September 24, 2016: Colloids and Surfaces. B, Biointerfaces
N Desroche, C Dropet, P Janod, J Guzzo
OBJECTIVE: This study was designed to evaluate the antibacterial activity of a wound dressing which combines polyacrylate fibres and a silver lipido-colloid matrix (UrgoClean Ag, silver polyabsorbent dressing), against biofilm of methicillin-resistant Staphylococcus aureus (MRSA). METHOD: Samples of silver polyabsorbent dressing and the neutral form of this dressing (UrgoClean) were applied to biofilms of MRSA formed on a collagen I-coated surface, cultured for 24 hours...
October 2, 2016: Journal of Wound Care
Hend E Salama, Gamal R Saad, Magdy W Sabaa
Chitosan biguanidine hydrochloride (ChG) and glutaraldehyde cross-linked chitosan biguanidine (CChG) were synthesized and characterized by Fourier transform infrared spectroscopy, (1)H NMR and (13)C NMR, X-ray diffraction, scanning electron microscopy (SEM) and thermal analyses (TGA and DTA). The results showed that ChG and CChG had a more amorphous structure than that of chitosan, and their thermal stability were slightly lower than that of chitosan. Colloidal silver nanoparticles (AgNPs) were prepared using borohydride reduction method and then investigated as fillers in partially cross-linked chitosan biguanidine...
October 2, 2016: Journal of Biomaterials Science. Polymer Edition
Priscila L L Freire, Allan J R Albuquerque, Isabela A P Farias, Teresinha Gonçalves da Silva, Jaciana Santos Aguiar, André Galembeck, Miguel A P Flores, Fabio C Sampaio, Thayza Christina Montenegro Stamford, Aronita Rosenblatt
The present study aimed to evaluate the antimicrobial activity and cytotoxicity of colloidal chitosan - silver nanoparticle - fluoride nanocomposites (CChAgNpFNc), with different silver nanoparticle shapes and sizes. The syntheses of CChAgNpFNc were performed with silver nitrate added to a chitosan solution, addition of a sodium borohydride solution and solid sodium fluoride. Solution of ascorbic acid was added to synthesize larger silver nanoparticles. CChAgNpFNc obtained: S1- 100% spherical, 8.7±3.1nm; S2- 97% spherical, 15...
September 15, 2016: International Journal of Biological Macromolecules
Peipei Yang, Jianzhong Zheng, Yong Xu, Qiao Zhang, Lin Jiang
Plasmonic metal nanoparticles attract intense research attention because of their fascinating surface plasmon resonance properties and their potential applications in diverse fields. Here, some of the recent research efforts on the synthesis and applications of plasmonic metal nanoparticles are highlighted. Starting from the colloidal synthesis of metal nanoparticles, various shaped silver and gold nanostructures are discussed. The applications of plasmonic nanoparticles in photocatalysis, surface-enhanced Raman spectroscopy (SERS), and devices are used as excellent examples showcasing the advantages of these nanoparticles...
September 13, 2016: Advanced Materials
Nerea Garcia-Velasco, Maite Gandariasbeitia, Amaia Irizar, Manuel Soto
Despite the increasing interest in silver nanoparticles toxicity still few works dealt with the hazards of nanosized Ag in soils (either dissolved in pore water or coupled to colloids) although disposal of biosolids in landfills has been reported as the major source of silver nanoparticles in terrestrial environments. Presently, Eisenia fetida was used to assess the toxicity of 5 nm sized PVP-PEI coated silver nanoparticles in soil through the implementation of different exposure media Standard Toxicity Tests (Paper Contact and Artificial Soil -OECD-207- and Reproduction -OECD-222- Tests) together with cellular biomarkers measured in extruded coelomocytes...
September 10, 2016: Ecotoxicology
Marimuthu Govindarajan, Shine Kadaikunnan, Naiyf S Alharbi, Giovanni Benelli
Mosquito control is facing key challenges, including outbreaks of new arbovirus threats. We proposed an eco-friendly synthesis of silver nanoparticles (AgNPs) employing a low-cost extract of Hugonia mystax. AgNPs were specified by UV, XRD, FTIR and EDX spectroscopy, SEM and TEM. AgNPs were more toxic to Anopheles stephensi, Aedes aegypti, and Culex quinquefasciatus larvae (LC50: 14.45, 15.86, and 17.46 μg/mL) if compared to aquatic biocontrol organisms Gambusia affinis, Diplonychus indicus, and Anisops bouvieri (LC50: 2567...
September 9, 2016: Artificial Cells, Nanomedicine, and Biotechnology
Raju R Kumal, Mohammad Abu-Laban, Corey R Landry, Blake Kruger, Zhenyu Zhang, Daniel J Hayes, Louis H Haber
The photocleaving dynamics of colloidal microRNA-functionalized nanoparticles are studied using time-dependent second harmonic generation (SHG) measurements. Model drug-delivery systems composed of oligonucleotides attached to either silver nanoparticles or polystyrene nanoparticles using a nitrobenzyl photocleavable linker are prepared and characterized. The photoactivated controlled release is observed to be most efficient on resonance at 365 nm irradiation, with pseudo-first-order rate constants that are linearly proportional to irradiation powers...
October 11, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Hina Singh, Juan Du, Tae-Hoo Yi
This study highlights the facile, reliable, cost effective, and ecofriendly synthesis of silver nanoparticles (AgNPs) using Borago officinalis leaves extract efficiently. The biosynthesis of AgNPs was verified by UV-Vis spectrum which showed the surface plasmon resonance (SPR) band at 422 nm. Transmission electron microscope (TEM) analysis revealed that the particles were spherical, hexagonal, and irregular in shape and had size ranging from 30 to 80 nm. The energy dispersive X-ray spectroscopy (EDX) and elemental mapping have displayed the purity and maximum distribution of silver in the AgNPs...
September 6, 2016: Artificial Cells, Nanomedicine, and Biotechnology
Rongchao Jin, Chenjie Zeng, Meng Zhou, Yuxiang Chen
Colloidal nanoparticles are being intensely pursued in current nanoscience research. Nanochemists are often frustrated by the well-known fact that no two nanoparticles are the same, which precludes the deep understanding of many fundamental properties of colloidal nanoparticles in which the total structures (core plus surface) must be known. Therefore, controlling nanoparticles with atomic precision and solving their total structures have long been major dreams for nanochemists. Recently, these goals are partially fulfilled in the case of gold nanoparticles, at least in the ultrasmall size regime (1-3 nm in diameter, often called nanoclusters)...
September 28, 2016: Chemical Reviews
Susanta Kumar Bhunia, Leila Zeiri, Joydeb Manna, Sukhendu Nandi, Raz Jelinek
Development of effective platforms for surface enhanced Raman scattering (SERS) sensing has mostly focused on fabrication of colloidal metal surfaces and tuning of their surface morphologies, designed to create "hot spots" in which plasmonic fields yield enhanced SERS signals. We fabricated distinctive SERS-active flexible films comprising polydimethylsiloxane (PDMS) embedding carbon dots (C-dots) and coated with silver nano-particles (Ag NPs). We show that the polymer-associated Ag NPs and C-dots intimately affected the physical properties of each other...
September 28, 2016: ACS Applied Materials & Interfaces
Honghua Zhang, Dilong Liu, Lifeng Hang, Xinyang Li, Guangqiang Liu, Weiping Cai, Yue Li
A facile route has been proposed for the fabrication of morphology-controlled periodic SiO2 hierarchical micro/nanostructured arrays by reactive ion etching (RIE) using monolayer colloidal crystals as masks. By effectively controlling the experimental conditions of RIE, the morphology of a periodic SiO2 hierarchical micro/nanostructured array could be tuned from a dome-shaped one to a circular truncated cone, and finally to a circular cone. After coating a silver thin layer, these periodic micro/nanostructured arrays were used as surface-enhanced Raman scattering (SERS)-active substrates and demonstrated obvious SERS signals of 4-Aminothiophenol (4-ATP)...
September 30, 2016: Nanotechnology
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