Synthesis and antibacterial activity of of silver nanoparticles
01 Jan 2009-Vol. 146, Iss: 1, pp 012024
TL;DR: Nanosilver is a promising candidate for development of future antibacterial therapies because of its wide spectrum of activity and its antimicrobial mechanism has not been clearly revealed.
Abstract: Silver nanoparticles have been known to have inhibitory and bactericidal effects but the antimicrobial mechanism have not been clearly revealed. Here, we report on the synthesis of metallic nanoparticles of silver using wild strains of Penicillium isolated from environment. Kinetics of the formation of nanosilver was monitored using the UV-Vis. TEM micrographs showed the formation of silver nanoparticles in the range 10–100 nm. Obtained Ag nanoparticles were evaluated for their antimicrobial activity against the gram-positive and gram-negative bacteria. As results, Bacillus cereus, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa were effectively inhibited. Nanosilver is a promising candidate for development of future antibacterial therapies because of its wide spectrum of activity.
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TL;DR: The different modes and mechanisms of antibacterial property were deciphered and recent approaches for green synthesis of metallic nanoparticles were discussed.
266 citations
TL;DR: The agar/AgNPs nanocomposite films possessed strong antibacterial activity against Listeria monocytogenes and Escherichia coli and could be applied to the active food packaging by controlling the food-borne pathogens.
205 citations
Cites methods from "Synthesis and antibacterial activit..."
...The 54 antimicrobial activity of AgNPs is known to depend on the composition, size, shape, 55 chemical functionality, and surface charge, which are greatly influenced by the preparation 56 methods of AgNPs (Martinez-Castanon, Nino-Martinez, Martinez-Gutierrez, Martinez-57 Mendoza, & Ruiz, 2008)....
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TL;DR: The results reveal that Ag/ZnO-clay composite is a promising bactericide that can be used for deactivating microbes in water.
150 citations
TL;DR: In this article, the authors used methanol leaves extract of L. reticulata to synthesize silver nanoparticles (Ag NPs) and tested for antimicrobial activity by agar well diffusion method against different pathogenic microorganisms and antioxidant activity was performed using DPPH assay.
Abstract: Biosynthesis of silver nanoparticles (Ag Nps) was carried out using methanol leaves extract of L. reticulata. Ag Nps were characterized based on the observations of UV–visible spectroscopy, transmission electron microscopy, and X-ray diffraction (XRD) analysis. These Ag Nps were tested for antimicrobial activity by agar well diffusion method against different pathogenic microorganisms and antioxidant activity was performed using DPPH assay. Further, the in vitro cytotoxic effects of Ag Nps were screened against HCT15 cancer cell line and viability of tumor cells was confirmed using MTT ((3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, a yellow tetrazole)) assay. The nuclear condensation was studied using the propidium iodide-staining method. The color change from green to dark brown and the absorbance peak at about 420 nm indicated the formation of nanoparticles. XRD pattern showed characteristic peaks indexed to the crystalline planes (111), (200) and (220) of face-centered cubic silver. The nanoparticles were of spherical shape with varying sizes ranging from 50 to 70 nm. Biosynthesized Ag Nps showed potent antibacterial activity and effective radical scavenging activity. MTT assay revealed a dose-dependent decrease in cell viability. Microscopic observations showed distinct cellular morphological changes indicating unhealthy cells, whereas the control appeared normal. Increase in the number of propidium iodide positive cells were observed in maximum concentration. Methanolic leaf extract of L. reticulata acts as an excellent capping agent for the formation of silver nanoparticles and demonstrates immense biological activities. Hence, these Ag NPs can be used as antibacterial, antioxidant as well as cytotoxic agent in treating many medical complications.
123 citations
Cites background from "Synthesis and antibacterial activit..."
...This might be due to denaturation of bacterial cell wall, blocking bacterial respiration, destabilization of outer membrane, and depletion of intracellular ATP (Maliszewska and Sadowski 2009)....
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...turation of bacterial cell wall, blocking bacterial respiration, destabilization of outer membrane, and depletion of intracellular ATP (Maliszewska and Sadowski 2009)....
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TL;DR: In this paper, the mechanisms of antibacterial activity of reduced graphene oxide (rGO)-nAg nanocomposite against several important human pathogenic multi-drug resistant bacteria, namely Gram-positive coccal Staphylococcus aureus and Gram-negative rod-shaped Escherichia coli and Proteus mirabilis are investigated.
Abstract: Reduced graphene oxide (rGO) is a promising antibacterial material, the efficacy of which can be further enhanced by the addition of silver nanoparticles (nAg). In this study, the mechanisms of antibacterial activity of rGO–nAg nanocomposite against several important human pathogenic multi-drug resistant bacteria, namely Gram-positive coccal Staphylococcus aureus and Gram-negative rod-shaped Escherichia coli and Proteus mirabilis are investigated. At the same concentration (100 µg/ml), rGO–nAg nanocomposite was significantly more effective against all three pathogens than either rGO or nAg. The nanocomposite was equally active against P. mirabilis and S. aureus as systemic antibiotic nitrofurantoin, and significantly more effective against E. coli. Importantly, the inhibition was much faster in the case of rGO–nAg nanocomposite compared to nitrofurantoin, attributed to the synergistic effects of rGO–nAg mediated contact killing and oxidative stress. This study may provide new insights for the better understanding of antibacterial actions of rGO–nAg nanocomposite and for the better designing of graphene-based antibiotics or other biomedical applications.
115 citations
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TL;DR: The results indicate that the bactericidal properties of the nanoparticles are size dependent, since the only nanoparticles that present a direct interaction with the bacteria preferentially have a diameter of approximately 1-10 nm.
Abstract: Nanotechnology is expected to open new avenues to fight and prevent disease using atomic scale tailoring of materials. Among the most promising nanomaterials with antibacterial properties are metallic nanoparticles, which exhibit increased chemical activity due to their large surface to volume ratios and crystallographic surface structure. The study of bactericidal nanomaterials is particularly timely considering the recent increase of new resistant strains of bacteria to the most potent antibiotics. This has promoted research in the well known activity of silver ions and silver-based compounds, including silver nanoparticles. The present work studies the effect of silver nanoparticles in the range of 1-100 nm on Gram-negative bacteria using high angle annular dark field (HAADF) scanning transmission electron microscopy (STEM). Our results indicate that the bactericidal properties of the nanoparticles are size dependent, since the only nanoparticles that present a direct interaction with the bacteria preferentially have a diameter of approximately 1-10 nm.
5,609 citations
TL;DR: These nontoxic nanomaterials, which can be prepared in a simple and cost-effective manner, may be suitable for the formulation of new types of bactericidal materials.
5,309 citations
TL;DR: This is the first comparative study on the bactericidal properties of silver nanoparticles of different shapes, and the results demonstrate thatsilver nanoparticles undergo a shape-dependent interaction with the gram-negative organism E. coli.
Abstract: In this work we investigated the antibacterial properties of differently shaped silver nanoparticles against the gram-negative bacterium Escherichia coli, both in liquid systems and on agar plates. Energy-filtering transmission electron microscopy images revealed considerable changes in the cell membranes upon treatment, resulting in cell death. Truncated triangular silver nanoplates with a {111} lattice plane as the basal plane displayed the strongest biocidal action, compared with spherical and rod-shaped nanoparticles and with Ag+ (in the form of AgNO3). It is proposed that nanoscale size and the presence of a {111} plane combine to promote this biocidal property. To our knowledge, this is the first comparative study on the bactericidal properties of silver nanoparticles of different shapes, and our results demonstrate that silver nanoparticles undergo a shape-dependent interaction with the gram-negative organism E. coli.
3,697 citations
TL;DR: Use of nanosilver is becoming more and more widespread in medicine and related applications and due to increasing exposure toxicological and environmental issues need to be raised.
1,756 citations
TL;DR: The antibacterial effect of silver nanoparticles used in this study was found to be far more potent than that described in the earlier reports and was more pronounced against gram-negative bacteria than gram-positive organisms.
Abstract: In the present study, we report the preparation of silver nanoparticles in the range of 10‐15 nm with increased stability and enhanced anti-bacterial potency. The morphology of the nanoparticles was characterized by transmission electron microscopy. The antibacterial effect of silver nanoparticles used in this study was found to be far more potent than that described in the earlier reports. This effect was dose dependent and was more pronounced against gram-negative bacteria than gram-positive organisms. Although bacterial cell lysis could be one of the reasons for the observed antibacterial property, nanoparticles also modulated the phosphotyrosine profile of putative bacterial peptides, which could thus affect bacterial signal transduction and inhibit the growth of the organisms.
1,507 citations