This technology will support nanoparticle-based recording media.

Silver is also found to be non-toxic to humans in minute concentrations. The microorganisms are unlikely to develop resistance against silver as compared to antibiotics as silver attacks a broad range of targets in the microbes 49. Experimental trials are needed to understand the toxicity. There are some questions, which need to be addressed, such as, the exact mechanism of interaction of silver nanoparticles with the bacterial cells, how the surface area of nanoparticles influence its killing activity, use of animal models and clinical studies to get a better understanding of the antimicrobial efficiency of silver dressings, the toxicity if any of the silver dressings, etc.

Particularly, silver nanoparticles

  nanoparticles in fabric are used to kill bacteria, making clothing odor-resistant.

Syntheses of Silver Nanoparticles and Their Property

A is being developed for fuel cells that produces twelve times more catalytic activity than pure platinum. In order to achieve this performance, researchers anneal nanoparticles to form them into a crystalline lattice, reducing the spacing between platinum atoms on the surface and increasing their reactivity.

The nanoparticles with a diameter of 20 nm are obtained [].

Due to incredible properties nanoparticles have become significant in many fields in the recent years, such as energy, health care, environment, agriculture, etc. The preparation of nanoparticles are carried out either by (i) Nanoparticles synthesis or by (ii) Processing of nanomaterials into nanostructure particles 3. The silver nanoparticles are prepared by using physical, chemical and biological methods 4. The physical and chemical methods are very expensive 5. Biological methods of nanoparticles synthesis would help to remove harsh processing conditions by enabling the synthesis at physiological pH, temperature, pressure, and at the same time at lower cost. Large number of micro organisms have been found capable of synthesizing inorganic nanoparticles composite either intra or extracellularly 6.

Reaction conditions of biosynthesis of silver nanoparticles (b-AgNPs) using  leaf extract.
Over the past few decades, many synthetic methods of silver nanoparticles have been studied.

The synthesis of silver nanoparticles by ..

Highly monodisperse sodium citrate-coated spherical silver nanoparticles (Ag NPs) with controlled sizes ranging from 10 to 200 nm have been synthesized by following a kinetically controlled seeded-growth approach via the reduction of silver nitrate by the combination of two chemical reducing agents: sodium citrate and tannic acid. The use of traces of tannic acid is fundamental in the synthesis of silver seeds, with an unprecedented (nanometric resolution) narrow size distribution that becomes even narrower, by size focusing, during the growth process. The homogeneous growth of Ag seeds is kinetically controlled by adjusting reaction parameters: concentrations of reducing agents, temperature, silver precursor to seed ratio, and pH. This method produces long-term stable aqueous colloidal dispersions of Ag NPs with narrow size distributions, relatively high concentrations (up to 6 × 1012 NPs/mL), and, more important, readily accessible surfaces. This was proved by studying the catalytic properties of as-synthesized Ag NPs using the reduction of Rhodamine B (RhB) by sodium borohydride as a model reaction system. As a result, we show the ability of citrate-stabilized Ag NPs to act as very efficient catalysts for the degradation of RhB while the coating with a polyvinylpyrrolidone (PVP) layer dramatically decreased the reaction rate.

The reduction of aqueous chromium (III) at silver nanoparticle modified electrodes

Silver nanoparticles: Synthesis methods, bio …

The exact mechanism of anti-bacterial activity using colloidal biosynthesized silver nanoparticles (b-AgNPs) is poorly understood. However, combination of our results and published literature entirely give us an idea about the formation of ROS which is responsible for the cytotoxicity of bacteria cells in presence of b-AgNPs. The bio-synthesized silver nanoparticles may interact with the cell wall of the which may destabilize the plasma-membrane potential (Fig..f-h) and reduced the levels of intracellular adenosine triphosphate (ATP) resulting in bacterial cell death (, ). We assume that one, or combination of the following reasons may help to explain the bacterial cell death using b-AgNPs.

Silver nanoparticles are important as ..

(i) Glutathione contributes the role in cellular protective system from oxidative stress (). Moreover cellular protein thiol groups are protected by glutathione (). The internalized bio-synthesized silver nanoparticles inside the cells may generate silver ions that interact with cellular glutathione and oxidize it. This oxidized glutathione results in formation of excess ROS that may help bacterial cellular toxicity and consequently inhibition of bacterial growth. (ii) Secondly, glutathione oxidation by silver ions may increase the lipid peroxidation in cellular membrane that may cause leakage of cellular constituents through membrane damage (). (iii) Thirdly, silver nanoparticles may interact with sulphur and phosphorous groups of the DNA due to their soft acidic nature (, ). This type of interaction may help in the damage of chromosomal DNA and plasmid DNA (, ), (iv) we have observed the lower level of catalase (anti-oxidant enzyme) in bacterial cell lysate when bacteria cells were treated with b-AgNPs. Lower level of catalase is responsible for oxidative stress, which help in the up regulation of several stress proteins (presented in Fig..c) including heat shock proteins. Results together support stress related antibacterial mechanisms in presence of b-AgNPs. In order to know the exact mechanism for silver nanoparticles induced cellular toxicity, rigorous research needs to be done systematically. Most recently, Zhang et al demonstrated that ROS generation using magnetic nanoparticles is responsible for both anti-bacterial and anti-cancer activity (). The probable mechanism of antibacterial effect of b-AgNPs is shown in the Scheme 2 (Figure ).