Silver nanoparticles as a new generation of antimicrobials.

Green synthesis of metal nanoparticles using plants

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Molecular Evolutionary Genetics Analysis

Silver nanoparticles are nanoparticles of silver which are in the range of 1 and 100 nm in size. Silver nanoparticles have unique properties which help in molecular diagnostics, in therapies, as well as in devices that are used in several medical procedures. The major methods used for silver nanoparticle synthesis are the physical and chemical methods. The problem with the chemical and physical methods is that the synthesis is expensive and can also have toxic substances absorbed onto them. To overcome this, the biological method provides a feasible alternative. The major biological systems involved in this are bacteria, fungi, and plant extracts. The major applications of silver nanoparticles in the medical field include diagnostic applications and therapeutic applications. In most of the therapeutic applications, it is the antimicrobial property that is being majorly explored, though the anti-inflammatory property has its fair share of applications. Though silver nanoparticles are rampantly used in many medical procedures and devices as well as in various biological fields, they have their drawbacks due to nanotoxicity. This review provides a comprehensive view on the mechanism of action, production, applications in the medical field, and the health and environmental concerns that are allegedly caused due to these nanoparticles. The focus is on effective and efficient synthesis of silver nanoparticles while exploring their various prospective applications besides trying to understand the current scenario in the debates on the toxicity concerns these nanoparticles pose.

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Silver nanoparticles: mechanism of antimicrobial action, synthesis, medical applications, and toxicity effects

Synthesis of metallic nanoparticles using plant extracts.

Extracellular production of metal nanoparticles by several strains of the fungus Fusarium oxysporum was carried out It was found that aqueous silver ions when exposed to several Fusarium oxysporum strains are reduced in solution, thereby leading to the formation of silver hydrosol The silver nanoparticles were in the range of 20–50 nm in dimensions The reduction of the metal ions occurs by a nitrate-dependent reductase and a shuttle quinone extracellular process The potentialities of this nanotechnological design based in fugal biosynthesis of nanoparticles for several technical applications are important, including their high potential as antibacterial material

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Mechanistic aspects of biosynthesis of silver nanoparticles by several Fusarium oxysporum strains.

Microorganisms play an important role in toxic metal remediation through reduction of metal ions. Studies demonstrated that silver ions may be reduced extracellularly using Fusarium oxysporum to generate stable gold or silver nanoparticles in water. These particles can be incorporated in several kinds of materials such as cloths. These cloths with silver nanoparticles are sterile and can be useful in hospitals to prevent or to minimize infection with pathogenic bacteria such as Staphylococcus aureus. In this work, the extracellular production of silver nanoparticles by F. oxysporum and its antimicrobial effect when incorporated in cotton fabrics against S. aureus were studied. In addition, all effluent was bioremediated using treatment with C. violaceum. The results showed that cotton fabrics incorporated with silver nanoparticles displayed a significant antibacterial activity against S. aureus. The effluent derived from the process was treated with C. violaceum and exhibited an efficient reduction in the silver nanoparticles concentration. In conclusion, it was demonstrated the application of biological synthesis to silver nanoparticles production and its incorporation in cloths, providing them sterile properties. Moreover, to avoid any damage to the environment the effluent containing silver nanoparticles can be treated with cyanogenic bacterial strains.

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Antibacterial Effect of Silver Nanoparticles Produced by Fungal Process on Textile Fabrics and Their Effluent Treatment

Exploitation of Aspergillus niger for Synthesis of Silver Nanoparticles

Metal nanoparticles have been studied and applied in many areas including the biomedical, agricultural, electronic fields, etc. Several products of colloidal silver are already on the market. Research on new, eco-friendly and cheaper methods has been initiated. Biological production of metal nanoparticles has been studied by many researchers due to the convenience of the method that produces small particles stabilized by protein. However, the mechanism involved in this production has not yet been elucidated although hypothetical mechanisms have been proposed in the literature. Thus, this review discusses the various mechanisms provided for the biological synthesis of metal nanoparticles by peptides, bacteria, fungi, and plants. One thing that is clear is that the mechanistic aspects in some of the biological systems need more detailed studies.

Mechanistic aspects in the biogenic synthesis of extracellular metal nanoparticles by peptides, bacteria, fungi, and plants

As propriedades da prata sao conhecidas ha muitos anos. Recentemente, as nanoparticulas de prata tem chamado a atencao por sua atividade antimicrobiana que oferece a possibilidade de uso com propositos medicos e de higiene. Estas nanoparticulas de prata em diferentes formulacoes, com diferentes formas e tamanhos, exibem atividades antimicrobianas diferentes. Entretanto, os mecanismos da atividade antimicrobiana de ions e de nanoparticulas, assim como sua toxicidade em tecidos humanos nao estao totalmente esclarecidos. Esta revisao avalia o uso potencial de nanoparticulas de prata no controle de patogenicos com enfase sobre sua acao contra bacterias patogenicas, sua toxicidade e possiveis mecanismos de acao. The antimicrobial properties of silver have been known for thousands of years. Recently, silver nanoparticles have gained attention because of their antimicrobial activity which offers the possibility of their use for medical and hygiene purposes. Indeed, silver nanoparticles in different formulations and with different shapes and sizes exhibit variable antimicrobial activity. However, the mechanisms of antimicrobial activity of silver ions and silver nanoparticles, and their toxicity to human tissues are not fully characterized. This review evaluates the potential use of silver nanoparticles to control pathogens with emphasis on their action against pathogenic bacteria, their toxicity and possible mechanisms of action.

http://www.scielo.br/pdf/jbchs/v21n6/v21n6a02.pdf

Priscyla D. Marcato

Papers

Mechanistic aspects of biosynthesis of silver nanoparticles by several Fusarium oxysporum strains.

Antibacterial Effect of Silver Nanoparticles Produced by Fungal Process on Textile Fabrics and Their Effluent Treatment

Exploitation of Aspergillus niger for Synthesis of Silver Nanoparticles

Mechanistic aspects in the biogenic synthesis of extracellular metal nanoparticles by peptides, bacteria, fungi, and plants

Potential use of silver nanoparticles on pathogenic bacteria, their toxicity and possible mechanisms of action