• Journal of the Korean institute of surface engineering
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• v.42 no.1
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• pp.47-52
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• 2009

Cu-Ag powder having Core-Shell structure was prepared from by electroless plating method using agents such as $AgNO_3$, $NH_{4}OH$, Hydroquinone. Ag coated copper powders were analyzed using scanning electron microscopy(SEM) and energy dispersive X-ray spectrometer(EDX). The silver coating layer of copper powder was affected from various reaction conditions such as molar ratio of $NH_{4}OH$, $AgNO_3$, and pulp density. Free silver was generated below 0.1M or 0.3M and above of $NH_{4}OH$ mole ratio. Silver coating layer thickened as addition of $AgNO_3$. When the pulp density reached 12% with 0.2M $NH_{4}OH$, and 0.15M $AgNO_3$ at $4^{\circ}C$, silver was homogeneously distributed around the copper particles and free silver particles were not generated.

• Applied Chemistry for Engineering
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• v.27 no.5
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• pp.551-554
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• 2016

Silver particles were synthesized by chemical reduction with ionic liquids. Structure of silver particles were significantly affected by the cation parts of the ionic liquids. With increasing the length of the cation part, the smaller silver particles were formed regardless of the anion type. This is mainly attributed to the different stability of the ionic liquid structure formed by physical bond between cation parts. Among seven ionic liquids, [Omim][$PF_6$] was the most effective for synthesizing silver particles.

• Journal of the Korean Chemical Society
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• v.29 no.2
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• pp.158-163
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• 1985

The anodic oxidations of the Silver(I) / Silver(II) / Silver(III) system have been studied in aq. 2M $AgNO_3$ solution with Platinum and Carbon electrodes. It has been found that $Ag_7O_8NO_3$ can be produced at relatively higher current density. Deposited black Oxy-salt were analyzed with several methods such as oxidizing power, X-ray powder diffraction patterns, thermal analysis, and reduction curves. It decomposed to AgO upon being suspended in boiling water. AgO compound obtained from $Ag_7O_8NO_3$ were purer and denser than Alfa-product AgO.

• Bulletin of the Korean Chemical Society
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• v.35 no.4
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• pp.1001-1004
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• 2014

We have synthesized disc-like large silver nanomaterials that have nanostructured bumps on the surface using smaller nanoplate seeds. The size and shape of the bumpy nanostructures are rationally controlled by changing the concentrations of nanoplate seeds, silver ion, reductant, and citrate ion. Importantly, the synthetic mechanism of these bumpy nanostructures is remarkably similar to that of the conventional seed-mediated growth based on tiny seeds. We have further investigated the catalytic properties of the bumpy nanostructures for the reduction of 4-nitrophenol, which is associated with a concomitant color change from yellow to colorless.

• Plant Resources
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• v.3 no.1
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• pp.59-65
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• 2000

The opening process of cut calla flower was faster at 30 t than at lower temperatures as it could be expected from its tropical origin. Gibberellin enhanced the flower opening, however, it also speeded up senescent. Silver thiosulfate was effective in prolonging the vase life of the cut calla flower. Silver thiosulfate reduced ethylene generation by the flower and inhibited microbial growth in the flower stalk. Reduction in ethylene generation and inhibition of microbial growth is thought to be responsible for the extension of the vase life of cut calla flowers by silver thiosulfate.

• Advances in nano research
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• v.3 no.2
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• pp.97-109
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• 2015

Citrate ion is a commonly used reductant in metal colloid synthesis, undergoes strong surface interaction with silver nanocrystallites. The slow crystal growth observed as a result of the interaction between the silver surface and the citrate ion makes this reduction process unique compared to other chemical and radiolytic synthetic methods. The antimicrobial effects of silver (Ag) ion or salts are well known, but the effects of citrate coated Ag nanoparticles (CAgNPs) are scant. Herein, we have isolated biofilm causative bacteria and fungi from drinking water PVC pipe lines. Stable CAgNPs were prepared and the formation of CAgNPs was confirmed by UV-visible spectroscopic analysis and recorded the localized surface plasmon resonance of CAgNPs at 430 nm. Fourier transform infrared spectroscopic analysis revealed C=O and O-H bending vibrations due to organic capping of silver responsible for the reduction and stabilization of the CAgNPs. X-ray diffraction micrograph indicated the face centered cubic structure of the formed CAgNPs, and morphological studies including size (average size 50 nm) were carried out using transmission electron microscopy. The hydrodynamic diameter (60.7 nm) and zeta potential (-27.6 mV) were measured using the dynamic light scattering technique. The antimicrobial activity of CAgNPs was evaluated (in vitro) against the isolated fungi, Gram-negative and Gram-positive bacteria using disc diffusion method and results revealed that CAgNPs with 170ppm concentration are having significant antimicrobial effects against an array of microbes tested.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.155-155
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• 2003

• Applied Chemistry for Engineering
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• v.24 no.4
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• pp.416-422
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• 2013

In order to incorporate silver ions into the alginate, silver-alginate was prepared with aqueous solutions of silver nitrate. In the study, the silver-alginate was prepared by blending with poly vinylpyrrolidone solutions and the electrospinning was performed by using this blend solution. Antibacterial properties of silver-alginate/PVP solutions were estimated for Escherichia coli and Staphylococcus aureus by the colony counting test. Electrospinning conditions of silver-alginate/PVP solution were the tip-to-collector distance of 22 cm, the flow rate of the solution at 0.01 mL/min, and the voltage at 26 kV. The form and size of silver-alginate/PVP nanofibers were estimated by SEM and Image J. The average diameter of the electrospun SA5P15 fibers was 124 nm and showed a narrow diameter distribution. The reduction of bacteria for SA5P15 exhibited 99.9% after 24 h.

• Biomaterials Research
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• v.22 no.4
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• pp.328-336
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• 2018

Background: Biogenic fabrication of silver nanoparticles from naturally occurring biomaterials provides an alternative, eco-friendly and cost-effective means of obtaining nanoparticles. It is a favourite pursuit of all scientists and has gained popularity because it prevents the environment from pollution. Our main objective to take up this project is to fabricate silver nanoparticles from lichen, Usnea longissima and explore their properties. In the present study, we report a benign method of biosynthesis of silver nanoparticles from aqueous-ethanolic extract of Usnea longissima and their characterization by ultraviolet-visible (UV-vis), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) analyses. Silver nanoparticles thus obtained were tested for antimicrobial activity against gram positive bacteria and gram negative bacteria. Results: Formation of silver nanoparticles was confirmed by the appearance of an absorption band at 400 nm in the UV-vis spectrum of the colloidal solution containing both the nanoparticles and U. longissima extract. Poly(ethylene glycol) coated silver nanoparticles showed additional absorption peaks at 424 and 450 nm. FTIR spectrum showed the involvement of amines, usnic acids, phenols, aldehydes and ketones in the reduction of silver ions to silver nanoparticles. Morphological studies showed three types of nanoparticles with an abundance of spherical shaped silver nanoparticles of 9.40-11.23 nm. Their average hydrodynamic diameter is 437.1 nm. Results of in vitro antibacterial activity of silver nanoparticles against Staphylococcus aureus, Streptococcus mutans, Streptococcus pyrogenes, Streptococcus viridans, Corynebacterium xerosis, Corynebacterium diphtheriae (gram positive bacteria) and Escherichia coli, Klebsiella pneuomoniae and Pseudomonas aeruginosa (gram negative bacteria) showed that it was effective against tested bacterial strains. However, S. mutans, C. diphtheriae and P. aeruginosa were resistant to silver nanoparticles. Conclusion: Lichens are rarely exploited for the fabrication of silver nanoparticles. In the present work the lichen acts as reducing as well as capping agent. They can therefore, be used to synthesize metal nanoparticles and their size may be controlled by monitoring the concentration of extract and metal ions. Since they are antibacterial they may be used for the treatment of bacterial infections in man and animal. They can also be used in purification of water, in soaps and medicine. Their sustained release may be achieved by coating them with a suitable polymer. Silver nanoparticles fabricated from edible U. longissima are free from toxic chemicals and therefore they can be safely used in medicine and medical devices. These silver nanoparticles were stable for weeks therefore they can be stored for longer duration of time without decomposition.

• Advances in nano research
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• v.6 no.1
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• pp.81-92
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• 2018

Biosynthesis of nanoparticles has acquired particular attention due to its economic feasibility, low toxicity and simplicity of the process. Extracellular synthesis of nanoparticles by bacteria and fungi has been stated to be brought about by enzymes and other reducing agents that may be secreted in the culture medium. The present study was carried out to determine the underlying mechanisms of extracellular silver nanoparticle synthesis by Pseudomonas hibiscicola isolated from the effluent of an electroplating industry in Mumbai. Synthesized nanoparticles were characterized by spectroscopy and electron microscopic techniques. Protein profiling studies were done using Sodium Dodecyl Sulphate Polyacrylamide Gel Electrophoresis (1D-SDS PAGE) and subjected to identification by Mass Spectrometry. Characterization studies revealed synthesis of 50 nm nanoparticles of well-defined morphology. Total protein content and SDS PAGE analysis revealed a reduction of total protein content in test (nanoparticles solution) samples when compared to controls (broth supernatant). 45.45% of the proteins involved in the process of nanoparticle synthesis were identified to be oxidoreductases and are thought to be involved in either reduction of metal ions or capping of synthesized nanoparticles.