Silver nanoparticles antimicrobial activity

Dextran sulphate Silver nanoparticles Antimicrobial activity [13]... 

However the mechanism of the antimicrobial effect of silver nanoparticles is not well understood. It has been recently reported that Nanosilver represents a special physicochemical system which confers its antimicrobial activities via Ag-t [11]. According to Morones et al., the bactericidal effect of silver nanoparticles on microorganisms is connected not merely with the release of silver ions in solution [12]. Silver nanoparticles can also be attached to the surface of the cell membrane and drastically distnrb its proper function [12]. They could also penetrate inside the bacteria and canse farther damage by interacting with sulfur and phosphorus-containing componnds snch as DNA. 

To compare the bactericidal efficacy of silver nanoparticles and silver ions, the minimum inhibitory concentration (MIC) assays were conducted for gram-negative bacterium E. coli, gram-positive bacteria S. aureus and B. subtilis and fungus P. phoeniceum. The data on MICs are summarized in Table 18.1. The results demonstrated that the antimicrobial activity of silver ions was superior to that of silver nanoparticles against all microbes tested. 

The preparation of rrltrafine antimicrobial cellnlose acetate (CA) fibres with silver nanoparticles by direct electrospinning of a CA solution containing low levels of silver nitrate and characterised by viscosity, strrface tension and conductivity, followed by photoreduction using UV irradiation, is described. The fibres were characterised by SEM, TEM, XPS arrd artfirrticrobial activity and the resrrlts are discussed. 24 refs. 

Can embedding nanoparticles of silver into a polymer give the polymer antimicrobial properties Researchers tested the antimicrobial properties of a new composite material- the polymer poly(4-vinyl-N-hexylpyridinium bromide), known as NPVP, which attracts cations. It is known that silver ions from silver bromide and silver nitrate exhibit antimicrobial activity. Silver bromide was embedded into the NPVP polymer. Scientists tested the antimicrobial properties of the composite material. Their results, illustrated in the graph, show the growth of E. coli bacteria over a period of approximately four hours. Each line represents the E. coli population in response to the introduction of a particular substance. 

Sharma, V.K., Yngard, R.A., and Lin, Y. 2009. Silver nanoparticles Green synthesis and their antimicrobial activities. Arfv. Colloid Interface Sci. 145 83-96. 

Bankura, K.P., Maity, D., Mollick, M.M.R., Mondal, D., Bhowmick, B., Bain, M.K., et al., 2012. Synthesis, characterization and antimicrobial activity of dextran stabilized silver nanoparticles in aqueous medium. Carbohydr. Polym. 89 (4), 1159—1165. 

Among various types of nanomaterials, metal nanoparticles, especially silver nanoparticles, have great importance. Antimicrobial activity is the main feature determining the popularity of this nanometal. Sources of specialized scientific literature provide many reports on its preparation, properties, and applications in these fields of science or industry where aseptic and antiseptic effects are particularly desirable (medicine, nursing, cosmetology, optics, bioengineering, botany, construction industry, textile, and food industries) (Jung et al., 2008). 

Most the nanomaterials contain several antimicrobial properties and presently researchers are focused toward unraveling the pharmaceutical difficulties using these nanomaterials. Compared to other metals, silver nanoparticles play one of the most important roles in antimicrobial activity both extra- and intracellularly. After long... 

Kumar, D.A., Palanichamy, V., Roopan, S.M., 2014. Green synthesis of silver nanoparticles using Altemanthera dentata leaf extract at room temperature and their antimicrobial activity. Spectrochim. Acta A 127, 168—171. 

Singbal, G.R.B., Kasariya, K., Sbarma, R.A., Singb, P.R., 2011. Biosynthesis of silver nanoparticles using Ocimum sanctum (Tulsi) leaf extract and screening its antimicrobial activity. J. Nanopart. Res. 13, 2981—2988. 

Recently, the production of nanofibres using nanocomposites has attracted attention. This is due to the fact that this type of nanofibre combines the unique properties of nanocomposites with the outstanding characteristics of nanofibres. Metal/polymer nanocomposites have not only the potential to meet the requirements of applications such as photonic and electric sensors, filters, and artificial tissue, but also can act as catalysts. Silver nanoparticles are the most common embedded metal nanoparticles used in conjunction with polymers. This is because silver nanoparticles exhibit remarkable properties including catalytic activity, surface-enhanced Raman scattering activity, high electrical conductivity and antimicrobial activity. 

A dramatic effect on Pseudomonas fouling was observed when the silver nanoparticles were immobilized on a thin-film composite PA membrane (Lee et al. 2007). SEM measurements confirmed that all Pseudomonas cells were made inactive on the modified-membrane surface, while water fluxes and salt rejections remained unchanged. High antibacterial activity toward E. coli and 5. aureus was also found with CA membranes modified with Ag nanoparticles (Chou et al. 2005). However, a significant loss of silver was found as a result of water permeation, and the antibacterial activity of the membranes disappeared after 5 days (Son et al. 2004). The loss of the entrapped silver nanoparticles was also reported for modified PS membranes, which have a high antimicrobial activity toward E. coli, P. mendocina, and the MS2 bacteriophage (Zodrow et al. 2009). 

Metal oxide nanoparticles have also been proven to possess antimicrobial activity. Some examples inclnde MgO and CaO, ZnO, cerinm oxide and silver nanoparticles. " " ... 

Silver nanoparticles were incorporated into PIA-based films which were obtained by casting from a CF solution. To accelerate the release of silver, composites were prepared by adding pure or surfactant-modified cellulose nanoctystals. The TEM images showed that silver and cellulose particles were distributed homogenously, results which were confirmed by the improvement of barrier properties to o g gen and water. However, the migration from the films and the release of silver increased with the presence of cellulose, especially when cellulose was modified with a surfactant. A potential interaction between the surfactant and PLA that resulted in degradation of the polymeric matrix might be the cause of such an effect. This report did not include the antimicrobial activity analysis of the prepared films. ... 

M.M.G. Eouda, M.R. El-Aassar, S.S. Al-Deyab, Antimicrobial activity of carboxymethyl chitosan/polyethylene oxide nanoflbers embedded silver nanoparticles. Carbohydrate Polymers 92 (2) (2013) 1012-1017. 

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