Metallic nanoparticles antimicrobial activities

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... 

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. 

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

Yadav et al. (2006) reported that ZnO-NP (Fig. 9) possess higher antibacterial effects on microorganisms S. aureus and Salmonella that other metal oxide nanoparticles (Jones et al. 2007), and fair activity against E. coli and Bacillus phaeus (Tam et al. 2008). The antimicrobial activity of these nanoparticles is attributed to several mechanisms, including the release of antimicrobial ions (Kasemets et al. 2009),... 

Other metal as silver (Ag) is economical and has important antimicrobial activity properties (Sharma et al. 2009). However, the use of Ag as a reinforcement of thermoplastic materials requires a pretreatment of the metal, due to its natural size and its propensity to form agglomerates in the composite material. Improved properties are generally obtained when small dispersed nanodomains are observed (Wiley et al. 2007). In order to reduce the particle size, some authors synfliesized silver nanoparticles (Ag-NP) (Fig. 10). Controllable synthesis of this metal is the... 

Microbial cellulose is found to be an optimal material for skin tissue repair due to its ability to provide a moist environment for wound healing and pain free dress changing. Unfortrmately, microbial cellulose itself has no antimicrobial activity to prevent wound infection. However the lack of antimicrobial activity of microbial cellulose is the main issue to be tackled. To improve the antimicrobial activity of microbial cellulose, researchers have introduced different materials such as benzalkonium chloride, chitosan and metallic nanoparticles into microbial cellulose. Among them metallic nanoparticles such as copper, silver [56] and ZnO [57] have been recently reported as excellent antimicrobial agents. Due to the electron-rich oxygen atoms in the microbial cellulose macromolecules and the large surface area of nanoporous microbial cellulose effective as nanoreactor, the in-situ metallization technique was successfully applied to the synthesis of Ag and microbial cellulose nanocomposite, which could in turn serve as antimicrobial skin tissue repair material. 

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