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Varshney R.,Microbiology and Nanotechnology Research Laboratory | Bhadauria S.,Microbiology and Nanotechnology Research Laboratory
Nano Biomedicine and Engineering | Year: 2012

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. © 2012 Ratnika Varshney, et al.


Varshney R.,Microbiology and Nanotechnology Research Laboratory | Bhadauria S.,Microbiology and Nanotechnology Research Laboratory | Pasricha R.,National Physical Laboratory India
Nano Biomedicine and Engineering | Year: 2011

In present investigation, samples from wastewaters of electroplating industry were collected and analyzed for the concentration of Cu 2+ heavy metal. For the synthesis of copper nanoparticles, Pseudomonas stutzeri bacterial strain was used. The bacterial strain was isolated from soil and found that it produced 50-150 nm sized cubical copper nanoparticles from electroplating waste water. The nanoparticles have been characterized by UV-visible Spectrophotometer, X-ray diffraction, Scanning Electron Microscopy and Energy Dispersive X-ray Analysis. © 2011 R. Varshney, et al.


Mishra A.N.,Microbiology and Nanotechnology Research Laboratory | Bhadauria S.,Microbiology and Nanotechnology Research Laboratory | Pasricha R.,National Physical Laboratory India | Kushwah B.S.,R B S College
International Journal of Green Nanotechnology: Physics and Chemistry | Year: 2010

In this research work, gold nanostructures with different shapes, such as octahedrons, hexagons and triangles, have been synthesized within 20 min by reducing gold chloride (HAuCl 4) with dried, powdered Stevia rebaudiana, leaves, previously not exploited for the synthesis of gold nanoparticles. The nanoparticles were characterized and investigated by ultraviolet-visible (UV-Vis) spectrophotometry, high-resolution transmission electron microscopy (HR-TEM), energy-dispersive X-ray (EDX) spectroscopy, and X-ray diffraction (XRD). The UV-Vis spectrum of the aqueous medium containing gold nanostructures showed a peak at 539 nm corresponding to the surface plasmon resonance band (SPR) of gold nanoparticles. HR-TEM micrograph showed the formation of well-dispersed octahedral gold nanoparticles of size 8-20 nm. XRD spectrum of the gold nanoparticles "exhibited Bragg's pattern of reflection.". © 2009 Copyright Taylor and Francis Group, LLC.


Dubey M.,Microbiology and Nanotechnology Research Laboratory | Bhadauria S.,Microbiology and Nanotechnology Research Laboratory | Sharma V.K.,National JALMA Institute of Leprosy and other Mycobacterial Diseases ICMR
International Journal of Green Nanotechnology: Biomedicine | Year: 2012

Biosynthesis of nanoparticles by plant extracts is currently under exploration. Biological methods are a good competent to chemical procedures, which are environmentally friendly and convenient. We report the use of new plant extract of Cuscuta reflexa in the extracellular biosynthesis of silver nanoparticles. Bioactive silver nanoparticle synthesis was achieved by reacting the biomass of C. reflexa with aqueous solutions of silver nitrate (AgNO3) at ambient temperature. The formation of silver nanoparticles was confirmed by ultraviolet-visible (UV-Vis) spectroscopy, X-ray diffraction patterns, and transmission electron microscopy (TEM). In the present study we report the excellent antibacterial activity of silver nanoparticle (with C. reflexa extract) against gram-positive and gramnegative multi-drug-resistant (MDR) bacterial strains using a zone of inhibition method. Scanning electron microscopy (SEM) imaging studies revealed that silver nanoparticles physically damaged the bacterial cell and ultimately led to cell death. © Taylor & Francis Group, LLC.


Varshney R.,Microbiology and Nanotechnology Research Laboratory | Bhadauria S.,Microbiology and Nanotechnology Research Laboratory
Advanced Materials Letters | Year: 2010

This work reports a novel biological method for the synthesis of rod shaped silver nanoparticles by exploiting sundried Stevia rebaudiana leaves at ambient conditions. On treatment of aqueous solutions of silver with leaf powder, not only the rod shaped silver nanoparticles ranging from 80-200 nm diameter and 400-800 nm height, but also cubes ranging from 55 to 80 nm in size, could be rapidly fabricated. The rate of reduction is much faster than those observed in earlier studies, highlighting the possibility that biological methodologies will achieve rates of synthesis comparable to those of chemical methods. The approach also appears to be a cost-efficient alternative to conventional methods, so it would be suitable for developing a biological process for large scale production. Instead of the boiled leaf broth used in previous studies, sundried leaf biomass could be preserved as an excellent bio-reductant, conveniently available any time for biosynthesis of the nanoparticles. © 2010 VBRI press.


Varshney R.,Microbiology and Nanotechnology Research Laboratory | Bhadauria S.,Microbiology and Nanotechnology Research Laboratory | Pasricha R.,National Physical Laboratory India
JOM | Year: 2010

The exploitation of various biomaterials for the biosynthesis of nanoparticles is considered as green technology as it does not involve any harmful chemicals. The present study reports the synthesis of copper nanoparticles which involves non-pathogenic bacterial strain Pseudomonas stutzeri, isolated from soil. These copper nanoparticles are further characterized for size and shape distributions by ultraviolet-visible spectroscopy, x-ray diffraction, and high resolution transmission electron microscopy techniques. The results showed that the particles are spherical and quite stable in nature and shows surface plasmon resonance clearly featured in the optical spectra in visible region. © 2010 TMS.

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