Antimicrobial Properties Of Silver Nanoparticles Research Articles

In Vivo Evaluation of Complex Biogenic Silver Nanoparticle and Enoxaparin in Wound Healing

The burns treatment is difficult, uncomfortable for the patient, and expensive for health system. Due to antimicrobial properties of silver nanoparticles (AgNP), these particles can avoid bacterial infection in wound and accelerate the wound healing. Furthermore, the complexation of AgNP with enoxaparin (low molecular weight heparin) may improve the healing process of lesions due to anti‐inflammatory and angiogenic activity of enoxaparin (Enox). The aim of this study was evaluated the activity and toxicity of biogenic AgNP and AgNP complexed with Enox in in vivo burn wound model. AgNP was produced by biosynthesis method using Fusarium oxysporum. AgNP (20–40 nm) exhibited high stability due to protein capping around the particles that was confirmed by TEM, fluorescence spectroscopy, and FTIR. The wound contraction in in vivo model, after 28 days of treatment, was 55, 89, 91, and 95% for control, Enox, AgNP, and AgNP‐Enox groups, respectively. No clear toxic effects in the biochemistry and hematological parameters were verified in all treated groups. However, in the AgNP‐Enox group, a statistically significant increase in the urea levels was observed indicating increased proteolysis due to inflammation process. The results demonstrated that the complex AgNP‐Enox is interesting for wound healing decreasing the time of lesions healing.

Exposure to silver nanoparticles induces size- and dose-dependent oxidative stress and cytotoxicity in human colon carcinoma cells

The antimicrobial properties of silver nanoparticles (AgNPs) have made these particles one of the most frequently utilized nanomaterials in consumer products; therefore, a comprehensive understanding of their toxicity is necessary. In particular, information about the cellular uptake and size dependence of AgNPs is insufficient.In this study, we evaluated the size-dependent effects of AgNPs by treating the human LoVo cell line, an intestinal epithelium model, with spherical AgNPs of well-defined sizes (10, 20, 40, 60 and 100nm). The cellular uptake was visualized by confocal laser scanning microscopy, and various cytotoxicity parameters were analyzed in a size- and dose-dependent manner. In addition, the cellular proteomic response to 20 and 100nm AgNPs was investigated to increase the understanding of potential mechanisms of action. Our data indicated that cellular uptake and toxicity were regulated by size; smaller particles easily penetrated the cells, and 100nm particles did not. It was hypothesized that this size-dependent effect resulted from the stimulation of a signaling cascade that generated ROS and inflammatory markers, leading to mitochondrial dysfunction and subsequently inducing apoptosis. By contrast, the cell proliferation, was independent of AgNPs particle size, indicating a differentially regulated, ROS-independent pathway.

Silicone Rubber and Microcrystalline Cellulose Composites with Antimicrobial Properties

The goal of this study was to create polydimethylsiloxane (PDMS) and microcrystalline cellulose (MCC) composites with high mechanical properties and antimicrobial activity. Vinyl-terminated PDMS was mixed with bifunctional filler, which combines MCC stiffness and antimicrobial properties of silver nanoparticles. To provide antimicrobial properties the silver nanoparticles in situ were synthesized by chemical reducing method in MCC aqueous suspension. Silver nanoparticles (AgNPs) concentration deposited on MCC particles surface was varied. The morphology, antimicrobial activity and mechanical properties of PDMS/MCC composites and their components have been investigated. It was shown that the combination of MCC/AgNPs as a filler and PDMS as matrix advantages bring multifunctional properties to polymer matrix composite. DOI: http://dx.doi.org/10.5755/j01.ms.20.1.4397

Influence of stabilizers on the antimicrobial properties of silver nanoparticles introduced into natural water

Physical, chemical and biochemical properties of silver nanoparticles (AgNPs) depend to a great extent on their size, shape, size distribution, and stabilizers located on their surface. This study focused on two typical stabilizers, namely citrates (cit), low molecular ions protecting nanoparticles by electrostatic repulsion, and polyvinylpyrrolidone (PVP), a hydrophilic, neutral, high molecular polymer protecting nanoparticles by steric stabilization. Natural bacterioplankton was collected from a eutrophic, downtown lake and exposed to five concentrations (0.1–5 mg/L) of AgNPs-PVP and AgNPs-cit. Responses were monitored after 1, 3, 5 and 7 days of exposure, by evaluating the survival rate of bacteria, their respiratory activity, and the general activity of extracellular esterases. A significantly better (greater) survival rate of bacterioplankton was observed in water with an addition of AgNPs-cit. The inhibition of extracellular esterases was observed only in samples containing AgNPs-PVP. The inhibitory effect increased proportionally to the concentration of AgNPs-PVP applied. Within the studied concentration range, there was no statistically significant inhibition of bacterioplankton respiratory activity by AgNPs-PVP and AgNPs-cit.

Development of intracanal formulation containing silver nanoparticles.

This study aimed to synthetize, characterize and evaluate the antimicrobial properties of silver nanoparticles to be used in the development of a root intracanal formulation. Silver nanoparticles (AgNPs) were obtained by reduction of silver nitrate with sodium borohydride and characterized by UV-Visible spectrophotometry, scanning electron microscopy (SEM) and dynamic light scattering (DLS). The antimicrobial activity of nanoparticle formulation was evaluated by determinations of the minimum inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) against different bacterial species by the microdilution method, according to recommendations of the Clinical and Laboratory Standards Institute (CLSI). Three potential vehicles, hydroxyethylcellulose, Carbomer and polyethylene glycol were tested as carriers for formulations containing AgNPs. The efficiency of the synthesis method chosen to produce AgNPs was demonstrated by four characterization techniques. The nanoparticles showed antibacterial activity against all species tested. Incorporation of AgNPs into all experimental vehicles produced stable formulations but the one in hydroxyethylcellulose presented better physical proprieties. The results indicate that silver nanoparticles are potential antiseptic agents to be used in root canals and incorporation in adequate vehicles may favor a broader application.

The Impact of Nano-Silver on Bacterial Aerobic Nitrate Reductase

Due to the effective antimicrobial properties of silver nanoparticles (Ag-NPs), these particles are receiving an extensive interest for applying in wide range of consumer products and water purification systems. Entering the Agbased material in wastewater system can influence the biological cycle such as nitrogen. Denitrification as a part of nitrogen cycle is an effective biological process in wastewater systems which can be affected by Ag-NPs. The objective of this research was to study the impact of Ag-NPs on aerobic nitrate reduction. We showed that Rhizobium sp and Azotobacter sp isolates were able to reduce nitrate aerobically. Adding 0.2 ppm of Ag-NPs in culture medium of Azotobacter PHB+ enhanced the nitrate reduction activity about 20% and Ag-NPs at this concentration has no significant effect on the nitrate reduction activity of periplasmic extracts of the selected isolates in aerobic conditions. Thus, it seems that entering certain concentration of Ag-NPs in environments has no significant impact on microbial aerobic denitrification as a certain part of nitrogen cycle.

The Impact of Silver Nanoparticles on Bacterial Aerobic Nitrate Reduction Process

Due to the effective antimicrobial properties of silver nanoparticles (Ag NPs), these particles are receiving an extensive interest for applying in wide range of consumer products and water purification systems. Entering the Ag-based material in wastewater system can influence the biological cycle such as nitrogen. Denitrification as a part of nitrogen cycle is an effective biological process in wastewater systems which can be affected by Ag NPs. The objective of this research was to study the impact of Ag NPs on aerobic nitrate reduction. We showed that Rhizobium sp and Azotobacter sp isolates were able to reduce nitrate aerobically. Adding 0.2 ppm of Ag NPs in culture medium of Azotobacter PHB+ enhanced the of the nitrate reduction activity about 20% and Ag NPs at this concentration has no significant effect on the nitrate reduction activity of periplasmic extracts of the selected isolates in aerobic conditions. Thus, entering certain ation of Ag NPs in environments has no significant impact on microbial aerobic denitrification as an important part of nitrogen cycle.

Antibacterial activity of silver nanoparticles grafted on stone surface

Microbial colonization has a relevant impact on the deterioration of stone materials with consequences ranging from esthetic to physical and chemical changes. Avoiding microbial growth on cultural stones therefore represents a crucial aspect for their long-term conservation. The antimicrobial properties of silver nanoparticles (AgNPs) have been extensively investigated in recent years, showing that they could be successfully applied as bactericidal coatings on surfaces of different materials. In this work, we investigated the ability of AgNPs grafted to Serena stone surfaces to inhibit bacterial viability. A silane derivative, which is commonly used for stone consolidation, and Bacillus subtilis were chosen as the grafting agent and the target bacterium, respectively. Results show that functionalized AgNPs bind to stone surface exhibiting a cluster disposition that is not affected by washing treatments. The antibacterial tests on stone samples revealed a 50 to 80 % reduction in cell viability, with the most effective AgNP concentration of 6.7 μg/cm(2). To our knowledge, this is the first report on antimicrobial activity of AgNPs applied to a stone surface. The results suggest that AgNPs could be successfully used in the inhibition of microbial colonization of stone artworks.

Silver Nanoparticles and Their Antimicrobial Activity on a Few Bacteria

The antimicrobial effects of silver (Ag) ion or salts are well known, but the effects of silver nanoparticles on microorganisms have not been revealed clearly. Here, the antimicrobial properties of silver nanoparticles have been investigated using Bacillus subtilis and methicillin-resistant Staphylococcus aureus. Linoleic acid-protected fine and uniform silver nanoparticles have been prepared through the chemical reduction of silver ions by ethanol. X-ray diffraction study confirms the formation of silver nanoparticles. Transmission electron microscopic image shows a good size distribution of the particles in the range of 4–15 nm. Further, the antimicrobial activity of silver nanoparticles shows that these nanoparticles can be used as effective growth inhibitors.

Simple Analysis for Interaction between Nanoparticles and Fluorescence Vesicle as a Biomimetic Cell for Toxicological Studies

E-mail: korea1@kw.ac.krReceived August 14, 2012, Accepted September 12, 2012With continuing progress of nanotechnologies and various applications of nanoparticles, one needs to developa quick and fairly standard assessment tool to evaluate cytotoxicity of nanoparticles. However, muchcytotoxicity studies on the interpretation of the interaction between nanoparticles and cells are non-mechanisticand time-consuming. Here, we propose a simple screening method for the analysis of the interaction betweenseveral AgNPs (5.3 to 64 nm) and fluorescence-dye containing vesicles (12 µm) acting as a biomimetic cell-membrane. Fluorescence-dye containing vesicle was prepared using a fluorescence probe (1,6-diphenyl-1,3,5-hexatryene), which was intercalated into the lipid bilayer due to their hydrophobicity. Zeta potential of allmaterials except for bare-AgNPs (+32.8 mV) was negative ( −26 to −54 mV). The morphological change ( i.e.,rupture and fusion of vesicle, and release of dye) after mixing of the vesicle and AgNPs was observed byfluorescence microscopy, and fluorescence image were different with coating materials and surface charge ofx-AgNPs. In the results, we found that the surface charge of nanoparticles is the key factor for vesicle ruptureand fusion. This proposed method might be useful for analyzing the cytotoxicity of nanoparticles with cell-membranes instead of in vitro or in vivo cytotoxicity tests.Key Words : Silver nanoparticles, Toxicology, Biomimetic, Vesicle, FluorescenceIntroductionBecause of the plasmonic and antimicrobial properties ofsilver nanoparticles (AgNPs), these nanoparticles are alreadyfinding applications in wide fields, such as environmentaland biomedical sensors, and chemical and electrical appli-cations. With increasing utilization of AgNPs in consumerproducts, the potential release of AgNPs into the environ-ment and their impacts on the ecosystem and human healthhave been the issues of concern.

Structural characterization and antimicrobial properties of silver nanoparticles prepared by inverse microemulsion method

Silver nanoparticles have been synthesized in the inverse microemulsions formed using three different surfactants viz., cetyl-trimethyl ammonium bromide (CTAB), Tergitol and Triton X-100. We have done a systematic study of the effect of the surfactants on the particle size and properties of the silver nanoparticles. Microscopic studies show the formation of spheres, cubes and discs shaped silver nanostructures with the size in the range from 8 to 40nm. Surface plasmon resonance (SPR) peak was observed around 400nm and 500nm. In addition to SPR some extra peaks have also been observed due to the formation of silver metal clusters. The surface area increases from 3.45 to 15.06m2/g with decreasing the size of silver nanoparticles (40–8nm). To investigate the antimicrobial activity of silver nanoparticles, the nanoparticles were tested against the yeast, Candida albicans and the bacterium, E. coli. The results suggest very good antimicrobial activity of the silver nanoparticles against the test microbes. The mode of action of the antimicrobial activity was also proposed.

A Review: Biological Synthesis Of Silver and Copper Nanoparticles

The antimicrobial properties of silver nanoparticles were known since ancient times and silver ions are widely used as bactericidal agent. Researchers have also recommended the use of silver and copper ions as superior disinfectants for wastewater generated from hospitals containing infectious microorganisms. A wide range of nanophasic and nanostructured particles are being fabricated globally with the aim of developing clean, nontoxic and eco-friendly technologies. Use of ambient biological resources in this area of science is rapidly gaining importance owing to its growing success and simplicity. Currently, simple prokaryotes to complex eukaryotic organisms including higher angiospermic plants are used for the fabrication of NPs. One area of untapped potential is the use of microbes to fabricate copper nanoparticles. We are working on this aspect and successfully fabricated spherical copper nanoparticles of size 4-10 nm. This article presents a review of the ambient biological systems for fabrication of these nanoparticles and development of an updated knowledge base.

Antimicrobial effects of commercial silver nanoparticles are attenuated in natural streamwater and sediment

Given the demonstrated antimicrobial properties of silver nanoparticles (AgNPs), and the key role that microorganisms play in performing critical ecosystem functions such as decomposition and nutrient cycling, there is growing concern that AgNP pollution may negatively impact ecosystems. We examined the response of streamwater and sediment microorganisms to commercially available 21 ± 17 nm AgNPs, and compared AgNP impacts to those of dissolved-Ag added as AgNO(3). We show that in streamwater, AgNPs and AgNO(3) decreased respiration in proportion to dissolved-Ag concentrations at the end of the incubation (r(2) = 0.78), while in sediment the only measurable effect of AgNPs was a 14 % decrease in sulfate concentration. This contrasts with the stronger effects of dissolved-Ag additions in both streamwater and sediment. In streamwater, addition of dissolved-Ag at a level equivalent to the lowest AgNP dose led to respiration below detection, a 55 % drop in phosphatase enzyme activity, and a 10-fold increase in phosphate concentration. In sediment, AgNO(3) addition at a level equivalent to the highest AgNP addition led to a 34 % decrease in respiration, a 55 % increase in microbial biomass, and a shift in bacterial community composition. The results of this study suggest that, in similar freshwater environments, the short-term biological impacts of AgNPs on microbes are attenuated by the physical and chemical properties of streamwater and sediment.

Bactericidal Capacity of Silver Nanoparticles Associated with Gantrez S-97 on Streptococcus Mutans

Dental caries is a worldwide public health problem. S mutans plays an important role in the etiology of caries. There have been studies that showed the antimicrobial properties of silver nanoparticles are an effective agent to diminish S. mutans. The objective of this study was to evaluate the bactericidal and bacteriostatic effects of silver nanoparticles in addition to the Gantrez S-27 copolymer, on S mutans. We performed an in vitro experimental study using the liquid microdilution method in order to find the minimum inhibitory concentrations (MICs) and the minimum bactericidal concentrations (MBCs) with the subcultures obtained. The mixture was obtained by preparing 98 microg/mL of silver nanoparticles (10(3)mol) with Gantrez S-27 2%, in distilled water The readings were performed 24 hours after incubation and on 3 consecutive days. The results showed an average MTC of 6.12 microg /mL and MBC of 6.12 microg /mL. The addition of Gantrez 2% to silver nanoparticles does not alter its antimicrobial effect.

Antimicrobial properties of silver nanoparticles synthesized by bioaffinity adsorption coupled with TiO2 photocatalysis

AbstractBACKGROUND: On the basis of effective bioaffinity adsorption of Ag+, silver nanoparticles (Ag NPs) were synthesized on the surface of chitosan‐TiO2 adsorbent (CTA) by TiO2 photocatalysis for crystal growth.RESULTS: Among the microstructure characterizations of the resulting silver nanoparticles‐ loaded chitosan‐TiO2 adsorbent (Ag‐CTA), X‐ray diffraction (XRD) and scanning electron microscopy (SEM) equipped with energy dispersive X‐ray (EDX) revealed the formation of metallic Ag on the CTA, which was further confirmed by the surface plasmon resonance of Ag NPs in the UV‐visible absorption spectrum. The underlying mechanism behind the formation of Ag NPs on the CTA by TiO2 photoreduction was studied by Fourier transform infrared (FTIR) spectroscopy. The distinctive feature of Ag‐CTA after adsorption was the highly efficient antimicrobial activity in inactivating different test strains. In the case of Escherichia coli, 1.50 mg 1.67 wt% Ag‐CTA could totally inhibit 1.0–1.2 × 107 colony forming units (CFU) in 100 mL nutrient medium, which was superior to that previously reported.CONCLUSIONS: CTA effectively adsorbed the precious metal ion Ag+ onto active imprinting sites on the adsorbent and then exerted efficient antimicrobial effects against diverse microbes. This research will be useful for designing a novel CTA‐based wastewater treatment for multi‐functional performance. Copyright © 2010 Society of Chemical Industry

Evaluation of Silver Nanoparticle Toxicity in Skin in Vivo and Keratinocytes in Vitro

IntroductionProducts using the antimicrobial properties of silver nanoparticles (Ag-nps) may be found in health and consumer products that routinely contact skin.ObjectivesThis study was designed to assess the potential cytotoxicity of Ag-nps in human epidermal keratinocytes (HEKs) and their inflammatory and penetrating potential into porcine skin in vivo.Materials and MethodsWe used eight different Ag-nps in this study [unwashed/uncoated (20, 50, and 80 nm particle diameter), washed/uncoated (20, 50, and 80 nm), and carbon-coated (25 and 35 nm)]. Skin was dosed topically for 14 consecutive days. HEK viability was assessed by MTT, alamarBlue (aB), and CellTiter 96 AQueous One (96AQ). Release of the proinflammatory mediators interleukin (IL)-1β, IL-6, IL-8, IL-10, and tumor necrosis factor-α (TNF-α) were measured.ResultsThe effect of the unwashed Ag-nps on HEK viability after a 24-hr exposure indicated a significant dose-dependent decrease (p < 0.05) at 0.34 μg/mL with aB and 96AQ and at 1.7 μg/mL with MTT. However, both the washed Ag-nps and carbon-coated Ag-nps showed no significant decrease in viability at any concentration assessed by any of the three assays. For each of the unwashed Ag-nps, we noted a significant increase (p < 0.05) in IL-1β, IL-6, IL-8, and TNF-α concentrations. We observed localization of all Ag-nps in cytoplasmic vacuoles of HEKs. Macroscopic observations showed no gross irritation in porcine skin, whereas microscopic and ultrastructural observations showed areas of focal inflammation and localization of Ag-nps on the surface and in the upper stratum corneum layers of the skin.ConclusionThis study provides a better understanding Ag-nps safety in vitro as well as in vivo and a basis for occupational and risk assessment. Ag-nps are nontoxic when dosed in washed Ag-nps solutions or carbon coated.