One-pot fabrication of Ag @ Ag 2 O core-shell nanostructures for biosafe antimicrobial and antibiofilm applications (original) (raw)
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One-step synthesis of Ag nano-assemblies and study of their antimicrobial activities
Journal of Nanostructure in Chemistry, 2015
Three kinds of Ag nano-assemblies have been fabricated separately in a one-step reaction. These are designated as 3D-3D, shell-3/1D and 3D-1D nano-architectures. These nano-architectures were synthesized by polyol reduction method in the presence of polyvinyl pyrrolidone (PVP) at 120, 140, and 160°C, respectively. During the experiment, controlled temperature decrease has been carried out which successfully developed 3D-3D, and 3D-1D conjunction. The shell-3/1D nano-assembly was successfully developed at 140°C by gradual decreasing and subsequently increasing of temperature. The size and morphology of each product was characterized by transmission electron microscope (TEM). Surface plasmon resonance (SPR) behavior was analyzed by UV-Vis spectroscopy. The antimicrobial activities were also analyzed for gram positive bacteria like Enterococcus faecalis and Staphylococcus aureus, and gram negative like E. coli 0157:H7 and DH5a by scanned optical density (OD) and Kirby-Bauer process. The OD was measured by taking scanned UV-Vis absorption from 700-300 nm wavelength in LB (Luria-Bertani) broth media. Similarly Kirby-Bauer process was applied over LB agar media. The material was found unique in terms of morphology as well as in displaying its antimicrobial activities both for gram positive and gram negative bacteria.
Enhanced antibacterial activity of bifunctional Fe3O4-Ag core-shell nanostructures
Nano Research, 2009
In this article, we describe a simple onepot rapid synthesis route to produce uniform silver nanoparticles by thermal reduction of AgNO 3 using oleylamine as reducing and capping agent. To enhance the dispersal ability of as-synthesized hydrophobic silver nanoparticles in water, while maintaining their unique properties, a facile phase transfer mechanism has been developed using biocompatible block copolymer pluronic F-127. Formation of silver nanoparticles is confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM) and UVvis spectroscopy. Hydrodynamic size and its distribution are obtained from dynamic light scattering (DLS). Hydrodynamic size and size distribution of as-synthesized and phase transferred silver nanoparticles are 8.2 ± 1.5 nm (r = 18.3%) and 31.1 ± 4.5 nm (r = 14.5%), respectively. Antimicrobial activities of hydrophilic silver nanoparticles is tested against two Gram positive (Bacillus megaterium and Staphylococcus aureus), and three Gram negative (Escherichia coli, Proteus vulgaris and Shigella sonnei) bacteria. Minimum inhibitory concentration (MIC) values obtained in the present study for the tested microorganisms are found much better than those reported for commercially available antibacterial agents.
A novel in situ core@shell structure consisting of nanoparticles of Ag (Ag Nps) and AgI in agarose matrix (Ag@ AgI/agarose) has been synthesized as a hybrid, in order to have an efficient antibacterial agent for repetitive usage with no toxicity. The synthesized core@shell structure is very well characterized by XRD, UV−visible, photoluminescence, and TEM. A detailed antibacterial studies including repetitive cycles are carried out on Gram-negative Escherichia coli (E. coli) and Grampositive Staphylococcus aureus (S. aureus) bacteria in saline water, both in dark and on exposure to visible light. The hybrid could be recycled for the antibacterial activity and is nontoxic toward human cervical cancer cells (HeLa cells). The water insoluble Ag@AgI in agarose matrix forms a good coating on quartz, having good mechanical strength. EPR and TEM studies are carried out on the Ag@AgI/agarose and the bacteria, respectively, to elucidate a possible mechanism for killing of the bacteria.
TJPRC, 2013
Core-shell type Ag@TiO2 nano particles were prepared by one pot simultaneous reduction of AgNO3 and hydrolysis of Ti(IV) isopropoxide. They were characterized by absorption, XRD, FTIR, TGA, DSC and HR-TEM techniques. XRD patterns show the presence of anatase form of TiO2 and the noble metal (Ag). High resolution transmission electron microscopic measurements revealed that their size is below 50 nm. The antibacterial properties of Ag@TiO2 core-shell nanoparticles against Escherichia coli (E.coli) and Staphylococcus aureus (S.aureus) were examined by the agar diffusion method .As a result E.coli and S.aureus were shown to be substantially inhibited by Ag@TiO2 core-shell nanoparticles. These result demonstrated that TiO2 supported on the surface of Ag NPs without aggregation was proved to be a good novel antibacterial activity.
Industrial Crops and Products, 2019
Bringing two completely different properties into one nanostructure by using individual metals is a difficult goal to achieve. However, recently core-shell metallic nanostructures have introduced as a novel multifunctional nanomaterial with enhanced properties. Iron and silver based nanoparticles are among the most widely applicable nanomaterials in modern industries. Zero-valent iron nanostructures and silver nanoparticles are well known for their applications as catalyst and antimicrobial agent, respectively. In the present study, for the first time, we are reporting a successful fabrication of zero valent iron coated silver nanoparticles (ZVI@AgNPs) by using a green and one-pot synthesis approach. Aqueous leaf extract of Mediterranean cypress (Cupressus sempervirens) was used as a natural source of reducing and capping agent for reduction of both Ag + and Fe 3+ ions. Prepared nanostructures were characterised by a range of analytical techniques namely UV-vis spectroscopy, Transmission Electron Microscopy, X-Ray Diffraction, and Fourier Transform Infra-Red Spectroscopy. The prepared nanostructures were found to be an effective material for dye removal and were capable to remove 98.5% of the initial dye just after 4 h. Based on the results, zero valent iron coating enhanced the antimicrobial potential of AgNPs against Gram-positive bacteria (S. aureus), while showing no significant enhancement against Gramnegative bacteria (E. coli). ZVI@AgNPs, therefore, can be introduced as a novel nanostructure for application in aquatic filter materials to simultaneously reduce microbial and organic contaminants.
Green Synthesis of Ag Nanoparticles and Their Performance towards Antimicrobial Properties
Sains Malaysiana
Green synthesis is a forthcoming trend in the nanotechnology field where classical methods of synthesis are now replaced by inexpensive and eco-friendly methods. In this study, a green method has been developed for the synthesis of silver nanoparticles (AgNPs) where AgNPs were synthesised using water-based facile hydrothermal method. Silver nitrate (AgNO 3) and polyvinylpyrrolidone (PVP) were used as precursor and reducing agents to produce AgNPs. The molar ratio effect of the precursor and stabiliser, its reaction temperature and reaction time were investigated. X-ray Powder Diffraction (XRD), Field-Emission Scanning Electron Microscope (FESEM) and UV-Vis Spectrometry were used to characterise the AgNPs. The as-synthesized AgNPs with different molar ratios of the precursor to stabiliser were tested for antibacterial activities using Gram-positive bacteria (Bacillus subtilis) and Gram-negative bacteria (Escherichia coli). All the AgNPs samples exhibited antibacterial activities that were stronger against Gram-negative bacteria, as compared with Gram-positive bacteria. The diameter of the zone of inhibition (ZOI) increased with the increase of the AgNO 3 : PVP molar ratios. The results obtained proved that uniform AgNPs synthesized via green techniques have a high potential of influencing applications involving antimicrobial properties.
Core-Shell Au@Ag Nanoparticles Synthesized with Polyphenols as Antimicrobial Agents
Research Square (Research Square), 2021
In this work, we used a sequential method of synthesis for gold-silver bimetallic nanoparticles with core@shell structure (Au@AgNPs). Rumex hymenosepalus root extract (Rh), which presents high content in catechins and stilbenes, was used as reductor agent in nanoparticles synthesis. Size distribution obtained by Transmission Electron Microscopy (TEM) give a diameter mean of 36 nm for Au@AgNPs, and 24 nm for gold nanoparticles (AuNPs). The geometrical shapes of NPs were principally quasispherical. The thickness of silver shell over AuNPs are around 6 nm and covered by active biomolecules onto surface. Microstructural characterization included high angle annular dark eld images (HAADF) recorded with a scanning transmission electron microscope (STEM), Energy-Dispersive X-ray Spectroscopy (EDS), X-Ray Diffraction (XRD), UV-Vis Spectroscopy, and Zeta Potential. Also, a growth kinetic curve analysis using the Gompertz model for Staphylococcus aureus (Gram-positive), Escherichia coli (Gram-negative), and Candida albicans (yeast) were carried out for Au@AgNPs and monometallic AuNPs and AgNPs. Interestingly, Gompertz analysis indicates that Au@AgNPs present a higher effect on the growth kinetic of microorganisms than shown by monometallic nanoparticles.
Shape-controlled Synthesis and Antimicrobial Applications of Ag Nanoparticles
Recently, nanoscale inorganic materials are emerging as new class of antimicrobial materials to overcome the increasing antibiotics resistance developed in microorganisms. Amongst noble metals, silver ions have been recognized for decades to possess antimicrobial properties; hence they have been used extensively in bactericidal ointments. Most of the studies on Ag nanoparticles based antimicrobial agents have hitherto been restricted to use of spherical Ag nanoparticles, which demonstrate antimicrobial activity against Gram negative bacteria. However, a large group of pathogenic bacteria belong to Gram positive class. Considering that size as well as shape of Ag nanoparticles may have considerable effect on their properties, we have undertaken the task of studying the shape-dependent antimicrobial properties of Ag nanoparticles. This study particularly investigates the comparison of different shapes of nanoparticles (spherical, cubic and prismatic) against Gram negative and Gram positive bacteria. Amongst various shapes of Ag nanoparticles, Ag nanocubes were found to be significantly more effective in their antimicrobial activity against both Gram negative and Gram positive bacteria. Ag nanospheres were mainly effective against Gram negative bacteria, whereas Ag nanoprisms showed an intermediate activity.