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Colloidal silver

Hassan Mahmoodi Esfanddarani, Abolghasem Abbasi Kajani, Abdol-Khalegh Bordbar
High-quality colloidal silver nanoparticles (AgNP) were synthesised via a green approach by using hydroalcoholic extracts of Malva sylvestris . Silver nitrate was used as a substrate ion while the plant extract successfully played the role of reducing and stabilising agents. The synthesised nanoparticles were carefully characterised by using transmission electron microscopy, atomic-force microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy and UV-vis spectroscopy. The maximum absorption wavelengths of the colloidal solutions synthesised using 70 and 96% ethanol and 100% methanol, as extraction solvents, were 430, 485 and 504 nm, respectively...
June 2018: IET Nanobiotechnology
E Mitsai, A Kuchmizhak, E Pustovalov, A Sergeev, A Mironenko, S Bratskaya, D P Linklater, A Balčytis, E Ivanova, S Juodkazis
All-dielectric resonant micro- and nano-structures made of high-index dielectrics have recently emerged as a promising surface-enhanced Raman scattering (SERS) platform which can complement or potentially replace the metal-based counterparts in routine sensing measurements. These unique structures combine the highly-tunable optical response and high field enhancement with the non-invasiveness, i.e. chemically non-perturbing the analyte, simple chemical modification and recyclability. Meanwhile, commercially competitive fabrication technologies for mass production of such structures are still missing...
May 16, 2018: Nanoscale
Yang Liu, Yuanyuan Zhang, Qiangwei Kou, Yue Chen, Yantao Sun, Donglai Han, Dandan Wang, Ziyang Lu, Lei Chen, Jinghai Yang, Scott Guozhong Xing
Nowadays, synthetic organic dyes and pigments discharged from numerous industries are causing unprecedentedly severe water environmental pollution, and conventional water treatment processes are hindered due to the corresponding sophisticated aromatic structures, hydrophilic nature, and high stability against light, temperature, etc. Herein, we report an efficient fabrication strategy to develop a new type of highly efficient, low-cost, and magnetically recoverable nanocatalyst, i.e., FePt⁻Ag nanocomposites, for the reduction of methyl orange (MO) and rhodamine B (RhB), by a facile seed deposition process...
May 14, 2018: Nanomaterials
Fabio Polesel, Julia Farkas, Marianne Kjos, Patricia Almeida Carvalho, Xavier Flores-Alsina, Krist V Gernaey, Steffen Foss Hansen, Benedek Gy Plósz, Andy M Booth
Due to their widespread application in consumer products, elemental titanium (e.g., titanium dioxide, TiO2 ) and silver (Ag), also in nanoparticulate form, are increasingly released from households and industrial facilities to urban wastewater treatment plants (WWTPs). A seven-day sampling campaign was conducted in two full-scale WWTPs in Trondheim (Norway) employing only primary treatment. We assessed the occurrence and elimination of Ti and Ag, and conducted size-based fractionation using sequential filtration of influent samples to separate particulate, colloidal and dissolved fractions...
April 30, 2018: Water Research
Nicholas C Anderson, Peter E Chen, Aya K Buckley, Jonathan De Roo, Jonathan S Owen
Using 31P nuclear magnetic resonance (NMR) spectroscopy, we monitor the competition between tri-n-butylphosphine (Bu3P) and various amine and phosphine ligands for the surface of chloride terminated CdSe nanocrystals. Distinct 31P NMR signals for free and bound phosphine ligands allow their surface coverages to be directly measured. Ligands with a small steric profile achieve higher surface coverages (Bu3P = 0.5 nm-2, Me2P-n-octyl = 2.0 nm-2, NH2Bu = > 3 nm-2) and have greater relative binding affinity (Krel) for the nanocrystal (Krel: Me3P > Me2P-n-octyl ~ Me2P-n-octadecyl > Et3P > Bu3P)...
May 10, 2018: Journal of the American Chemical Society
Chunyan Yong, Xiaoqin Chen, Qian Xiang, Qiang Li, Xiaodong Xing
There is a significant need for magnetite-silver nanocomposites that exhibit durable and recyclable antimicrobial activity. In this study, magnetic iron oxide nanoparticles (Fe3 O4 NPs) coated with ethylenediamine-modified chitosan/polyacrylic acid copolymeric layer (Fe3 O4 @ECS/PAA) were fabricated. Subsequently, directly deposited silver (Ag) NPs procedure was carried out to form the antibacterial heterodimers of Fe3 O4 @ECS/PAA-Ag NPs. The composition and morphology of the resultant nanostructures were confirmed by FT-IR, XRD, TEM and TGA...
March 2018: Bioactive Materials
Adam Ferrick, Mei Wang, Taylor J Woehl
Electric field directed assembly of colloidal nanoparticles (NPs) has been widely adopted for fabricating functional thin films and nanostructured surfaces. While first order electrokinetic effects on NPs are well-understood in terms of classical models, effects of second order electrokinetics that involve induced surface charge are still poorly understood. Induced charge electroosmotic phenomena, such as electrohydrodynamic (EHD) flow, have long been implicated in electric field directed NP assembly with little experimental basis...
May 4, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Kim R Rogers, Jana Navratilova, Aleksandr Stefaniak, Lauren Bowers, Alycia K Knepp, Souhail R Al-Abed, Phillip Potter, Alireza Gitipour, Islam Radwan, Clay Nelson, Karen D Bradham
Given the potential for human exposure to silver nanoparticles from spray disinfectants and dietary supplements, we characterized the silver-containing nanoparticles in 22 commercial products that advertised the use of silver or colloidal silver as the active ingredient. Characterization parameters included: total silver, fractionated silver (particulate and dissolved), primary particle size distribution, hydrodynamic diameter, particle number, and plasmon resonance absorbance. A high degree of variability between claimed and measured values for total silver was observed...
April 1, 2018: Science of the Total Environment
Mian L Ooi, Katharina Richter, Catherine Bennett, Luis Macias-Valle, Sarah Vreugde, Alkis J Psaltis, Peter-John Wormald
Background: The management of recalcitrant chronic rhinosinusitis (CRS) is challenged by difficult-to-treat polymicrobial biofilms and multidrug resistant bacteria. This has led to the search for broad-spectrum non-antibiotic antimicrobial therapies. Colloidal silver (CS) has significant antibiofilm activity in vitro and in vivo against S. aureus, MRSA , and P. aeruginosa . However, due to the lack of scientific efficacy, it is only currently used as an alternative medicine. This is the first study looking at the safety and efficacy of CS in recalcitrant CRS...
2018: Frontiers in Microbiology
S Rajaboopathi, S Thambidurai
In the present study, green synthesis of silver nanoparticles (AgNPs) functionalized with seaweed (Padina gymnospora) extract was investigated. Thus synthesized AgNPs were coated on cotton fabric by pad try-cure method using citric acid as a cross linking agent. The chemical linkage of colloidal AgNPs onto the cellulosic structure are characterized and confirmed by FTIR, SEM, EDX and AFM analysis. The optical, crystalline and morphological features of the functionalized AgNPs were confirmed by UV-Visible, X-ray diffraction and TEM analysis...
April 18, 2018: Journal of Photochemistry and Photobiology. B, Biology
Yongshen Li, Yunna Song, Zheng Ma, Shuai Niu, Jihui Li, Ning Li
In this article, phosphonic acid silver-graphene oxide nanomaterials (Nano-PAS-GO) was synthesized from silver nitrate (AgNO3 ) solution and phosphoric graphene oxide (PGO) via the convenient ultrasonic-assisted method, and the structure and morphology were characterized, and the photocatalytic activity and recyclability were evaluated through photocatalyzing degradation of Rhodamin B (RhB) aqueous solution, and the possible photocatalytic mechanism was also discussed. Based on those, it was confirmed that Nano-PAS-GO has been synthesized from AgNO3 solution and PGO colloidal suspension under ultrasonic-assisted condition, and Nano-PAS-GO has consisted of phosphoric acid silver nanoparticles and GO with 2D lattice (2D GO lattice) connected in the form of C-P bonds, and the photodegradation rate of Nano-PAS-GO for RhB aqueous solution has reached 93...
June 2018: Ultrasonics Sonochemistry
Belén Hernández, Yves-Marie Coïc, Eduardo López-Tobar, Santiago Sanchez-Cortes, Bruno Baron, Fernando Pflüger, Sergei G Kruglik, Régis Cohen, Mahmoud Ghomi
Primarily known as the inhibitor of growth hormone release, the role of somatostatin in many other inhibiting activities upon binding to its five G-protein-coupled receptors has been elucidated. Because of the short half-life of somatostatin, a number of synthetic analogues were elaborated for this peptide hormone. Herein, after recalling the main somatostatin therapeutic interests, we present the dynamical behavior of somatostatin-14 and its two currently used synthetic cyclic analogues, octreotide and pasireotide...
2018: Advances in Protein Chemistry and Structural Biology
Cyril Muehlethaler, Yin Pak Cheng, Syed K Islam, John R Lombardi
Although ubiquitous on accident scenes, the polymers from headlight optics are often neglected in hit-and-run cases, and their evidential value restrained to direct comparison once a corresponding vehicle is found. Multilayered automotive paint fragments are preferred for their access to corresponding databases (PDQ, EUCAP) to infer models and brands of cars. The potential of polymers headlights for providing forensic intelligence has never been exploited, principally due to the lack of diversity, of appropriate databases, and of case examples...
March 31, 2018: Forensic Science International
Esmeralda Rangel-Vargas, Anais M Luna-Rojo, Arturo Cadena-Ramírez, Refugio Torres-Vitela, Carlos A Gómez-Aldapa, Angélica Villarruel-López, Alejandro Téllez-Jurado, José R Villagómez-Ibarra, Rosalía Reynoso-Camacho, Javier Castro-Rosas
The behavior of foodborne bacteria on whole and cut mangoes and the antibacterial effect of Hibiscus sabdariffa calyx extracts and chemical sanitizers against foodborne bacteria on contaminated mangoes were investigated. Mangoes var. Ataulfo and Kent were used in the study. Mangoes were inoculated with Listeria monocytogenes, Shigella flexneri, Salmonella Typhimurium, Salmonella Typhi, Salmonella Montevideo, Escherichia coli strains (O157:H7, non-O157:H7 Shiga toxin-producing, enteropathogenic, enterotoxigenic, enteroinvasive, and enteroaggregative)...
April 5, 2018: Journal of Food Protection
William J Anderson, Kamila Nowinska, Tanya Hutter, Sumeet Mahajan, Martin Fischlechner
Surface-enhanced Raman spectroscopy (SERS) is well known for its high sensitivity that emerges due to the plasmonic enhancement of electric fields typically on gold and silver nanostructures. However, difficulties associated with the preparation of nanostructured substrates with uniform and reproducible features limit reliability and quantitation using SERS measurements. In this work we use layer-by-layer (LbL) self-assembly to incorporate multiple functional building blocks of collaborative assemblies of nanoparticles on colloidal spheres to fabricate SERS sensors...
April 4, 2018: Nanoscale
Xiaohuan Ji, Guangqian Kan, Xiaoze Jiang, Bin Sun, Meifang Zhu, Yushan Sun
To address the pollution problem of organic dyes, monodispersed anionic silver nanoparticles (AgNPs) with an average size of 6 nm were prepared in water media via chemical reduction method from oleic acid and n-butyl amine. The aqueous solution of the resultant AgNPs was utilized as a photocatalyst to investigate the adsorption and photodegradation behaviors of organic dyes under different light irradiation. The morphology and surface characteristics of the synthesized AgNPs were probed using TEM, XRD, FTIR and zeta potential analysis...
March 6, 2018: Journal of Colloid and Interface Science
Amrita Chakraborty, Ann Candice Fernandez, Anirban Som, Biswajit Mondal, Ganapati Natarajan, Ganesan Paramasivam, Tanja Lahtinen, Hannu Häkkinen, Nonappa Nonappa, Thalappil Pradeep
We present the self-assembled structures of atomically precise, ligand-protected noble metal nanoclusters leading to encapsulation of plasmonic gold nanorods (GNRs). Unlike highly sophisticated DNA nanotechnology, our approach demonstrates a strategically simple hydrogen bonding-directed self-assembly of nanoclusters leading to octahedral nanocrystals encapsulating GNRs. Specifically, we use the p-mercaptobenzoic acid (pMBA) protected atomically precise nanocluster, Na4[Ag44(pMBA)30] and pMBA functionalized GNRs...
April 1, 2018: Angewandte Chemie
Ranganath L Munikamaiah, Saket K Jain, Kapil S Pal, Ajay Gaikwad
AIM: Silver colloidal nanoparticles have been incorporated into acrylic resins to induce antimicrobial properties. However, as additives, they can influence the mechanical properties of the final product. Mechanical properties are also dependent on different curing cycles. The aim of this study was to evaluate flexural strength of a denture base resin incorporated with different concentrations of silver colloidal nanoparticles subjected to two different curing cycles. MATERIALS AND METHODS: Lucitone 199 denture base resin was used into which silver colloidal nanoparticles were incorporated at 0...
March 1, 2018: Journal of Contemporary Dental Practice
Anupama Bhat, Kewei Huan, Tiana Cooks, Hacene Boukari, Qi Lu
Noble metallic nanoparticles (NPs) such as gold and silver nanoparticles (AuNPs and AgNPs) have been shown to exhibit anti-tumor effect in anti-angiogenesis, photothermal and radio therapeutics. On the other hand, cell membranes are critical locales for specific targeting of cancerous cells. Therefore, NP-membrane interactions need be studied at molecular level to help better understand the underlying physicochemical mechanisms for future applications in cancer nanotechnology. Herein, we report our study on the interactions between citrate stabilized colloidal AuNPs/AgNPs (10 nm in size) and giant unilamellar vesicles (GUVs) using hyperspectral dark-field microscopy...
March 28, 2018: International Journal of Molecular Sciences
Lorena Athie Goulart, Roger Gonçalves, Alessandra Alves Correa, Ernesto Chaves Pereira, Lucia Helena Mascaro
A glassy carbon electrode (GCE) was modified with multi-walled carbon nanotubes (MWCNT) and silver nanoparticles (AgNPs) and applied to the simultaneous determination of hydroquinone (HQ), catechol (CC), bisphenol A (BPA) and phenol by using square-wave voltammetry. The MWCNTs were deposited on the GCE and the AgNPs were then electrodeposited onto the MWCNT/GCE by the application of 10 potential sweep cycles using an AgNP colloidal suspension. The modified GCE was characterized by using SEM, which confirmed the presence of the AgNPs...
December 5, 2017: Mikrochimica Acta
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