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ABSTRACT: A single-step environmental friendly approach is employed to synthesize silver nanoparticles. The biomolecules found in plants induce the reduction of Ag(+) ions from silver nitrate to silver nanoparticles (AgNPs). UV-visible spectrum of the aqueous medium containing silver ions demonstrated a peak at 425 nm corresponding to the plasmon absorbance of silver nanoparticles. Transmission electron microscopy (TEM) showed the formation of well-dispersed silver nanoparticles in the range of 5-20 nm. X-ray diffraction (XRD) spectrum of the AgNPs exhibited 2θ values corresponding to the silver nanocrystal. The process of reduction is extracellular and fast which may lead to the development of easy biosynthesis of silver nanoparticles. Plants during glycolysis produce a large amount of H(+) ions along with NAD which acts as a strong redoxing agent; this seems to be responsible for the formation of AgNPs. Water-soluble antioxidative agents like ascorbic acids further seem to be responsible for the reduction of AgNPs. These AgNPs produced show good antimicrobial activity against common pathogens.
Biotechnology research international. 01/2011; 2011:454090.
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ABSTRACT: Bacillus megaterium isolated from fluvial zone of North Bihar has been used for the extracellular synthesis of metal nanoparticles (NPs) viz silver, lead and cadmium. The synthesized nanoparticles got accumulated on the surface of the cell wall of bacteria. Bacillus megaterium was grown aerobically and the cultures were challenged with the solutions of silver nitrate, lead nitrate and cadmium nitrate in requisite ambience of laboratory. Cell lysate obtained, after the centrifugation of cultures were characterized through optical absorption by UV-Vis Spectrophotometer, X-ray Diffraction (XRD), Transmission Electron Micrography (TEM) and Energy Dispersive Spectroscopy (EDS). These nanoparticles of Ag, Pb and Cd showed absorption peaks at ~ 435 nm, ~ 330 nm and ~ 410 nm respectively corresponding to the plasmon resonance of silver nanoparticles (AgNPs), cadmium nanoparticles (CdNPs) and lead nanoparticles (PbNPs). XRD Spectrum of these nanoparticles confirmed the formation of Ag, PbS and CdS particles by showing their respective characteristic peaks. TEM showed the production of these metal nanoparticles with particle size in the range of 10-20 nm.
International Research Journal of Biotechnology. 01/2011; 1:2141-5153071.
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ABSTRACT: In the present work silver nanoparticles (AgNPs) were synthesized extracellularly by bacteria Bacillus cereus collected from the riverine belt of Gangetic Plain of India. The microbes were isolated, screened and characterized by morpho-logical and biochemical analyses. The silver resistant strain was exposed to different concentrations of silver salt (Ag-NO 3). UV-visible spectrum of the supernatant of cell culture showed absorbance peak of AgNPs at ~ 435 nm.The shape and size of AgNPs were ascertained by High Resolution Transmission Electron Micrography (HRTEM), X-ray diffrac-tion (XRD) and Energy Dispersive spectroscopy (EDS). Average size of the synthesized AgNPs was found to be in the range of 10 -30 nm with spherical shape. AgNPs were tested against antibacterial potential of some common human pathogens.
Journal of Biomaterials and Nanobiotechnology. 01/2011; 2:156-162.
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ABSTRACT: Plants respond to heavy metal stress by metal complexation process like production of phytochelations or by other metal chelating peptides. In this paper we report the synthesis of silver nanoparticles (AgNPs) from the room dried stem and root of Ocimum sanctum. The broth of the plant is used as a reducing agent for the synthesis of Ag nanoparticles at room temperature. The reaction process was simple and was monitored by ultraviolet-visible spectroscopy (UV-vis). There was formation of highly stable silver nanoparticles in the solution. The morphology and crystalline phase of the NPs were determined from transmission electron microscopy (TEM), selected area electron diffraction (SAED) and X-ray diffraction (XRD) spectra. Transmission Electron Microscopy studies showed that the silver nanoparticles obtained from roots and stem were of sizes 10+/-2 and 5+/-1.5 nm, respectively. The various phytochemicals present within the ocimum plant result in effective reduction of silver salts to nanoparticles but their chemical framework is also effective at wrapping around the nanoparticles to provide excellent robustness against agglomeration.
Colloids and surfaces. B, Biointerfaces 11/2010; 81(1):81-6. · 2.60 Impact Factor
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ABSTRACT: Development of reliable and eco-friendly process for synthesis of metallic nanoparticles is an important step in the field of the application of nanotechnology. One of the options to achieve this objective is to use of biological systems. In this research we report extracellular biosynthesis of silver nanoparticles (AgNPs) exploiting the local biodiversity as an alternative to the chemical process. The plants of Desmodium species viz. Desmodium latifolium were selected. These plants occur as weeds in the gangetic river belt of Patna in Northern India. It was observed that the synthesis process was quite rapid and silver nanoparticles were formed within minutes of silver ion coming in contact with the plant filtrate. UV-visible spectrum of the aqueous medium containing silver ions demonstrated a peak at 425 nm corresponding to the plasmon absorbance of silver nanoparticles. Transmission electron microscopy (TEM) showed the formation of well-dispersed silver nanoparticles in the range of 5-30 nm. X-ray diffraction (XRD)-spectrum of the AgNPs exhibited 2θ values corresponding to the silver nanocrystal. FTIR analysis of the nanoparticles indicated the presence of proteins, which may be acting as capping agents around the nanoparticles. The process of reduction is extracellular and fast which may lead to the development of easy bio synthesis of silver nanoparticles.
Journal of Bionanoscience 11/2009; 3(2):97-104.
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ABSTRACT: The genomic diversity of Helicobacter pylori from the vast Indian subcontinent is largely unknown. We compared the genomes of 10 H. pylori strains from Ladakh, North India. Molecular analysis was carried out to identify rearrangements within and outside the cag pathogenicity island (cag PAI) and DNA sequence divergence in candidate genes. Analyses of virulence genes (such as the cag PAI as a whole, cagA, vacA, iceA, oipA, babB, and the plasticity cluster) revealed that H. pylori strains from Ladakh are genetically distinct and possibly less virulent than the isolates from East Asian countries, such as China and Japan. Phylogenetic analyses based on the cagA-glr motifs, enterobacterial repetitive intergenic consensus patterns, repetitive extragenic palindromic signatures, the glmM gene mutations, and several genomic markers representing fluorescent amplified fragment length polymorphisms revealed that Ladakhi strains share features of the Indo-European, as well as the East Asian, gene pools. However, the contribution of genetic features from the Indo-European gene pool was more prominent.
Journal of Clinical Microbiology 05/2005; 43(4):1538-45. · 4.15 Impact Factor
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Farhana Kauser,
Aleem A Khan,
M Abid Hussain,
Ian M Carroll, Naheed Ahmad,
Santosh Tiwari,
Yogesh Shouche,
Bimal Das,
Mahfooz Alam,
S Mahaboob Ali,
C M Habibullah,
Rafaela Sierra,
Francis Megraud,
Leonardo A Sechi,
Niyaz Ahmed
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ABSTRACT: The cag pathogenicity island (cag-PAI) is one of the major virulence determinants of Helicobacter pylori. The chromosomal integrity of this island or the lack thereof is speculated to play an important role in the progress of the gastroduodenal pathology caused by H. pylori. We determined the integrity of the cag-PAI by using specific flanking and internally anchored PCR primers to know the biogeographical distribution of strains carrying fully integral cag-PAI with proinflammatory behavior in vivo. Genotypes based on eight selected loci were studied in 335 isolates obtained from eight different geographic regions. The cag-PAI appeared to be disrupted in the majority of patient isolates throughout the world. Conservation of cag-PAI was highest in Japanese isolates (57.1%). However, only 18.6% of the Peruvian and 12% of the Indian isolates carried an intact cag-PAI. The integrity of cag-PAI in European and African strains was minimal. All 10 strains from Costa Rica had rearrangements. Overall, a majority of the strains of East Asian ancestry were found to have intact cag-PAI compared to strains of other descent. We also found that the cagE and cagT genes were less often rearranged (18%) than the cagA gene (27%). We attempted to relate cag-PAI rearrangement patterns to disease outcome. Deletion frequencies of cagA, cagE, and cagT genes were higher in benign cases than in isolates from severe ulcers and gastric cancer. Conversely, the cagA promoter and the left end of the cag-PAI were frequently rearranged or deleted in isolates linked to severe pathology. Analysis of the cag-PAI genotypes with a different biogeoclimatic history will contribute to our understanding of the pathogen-host interaction in health and disease.
Journal of Clinical Microbiology 12/2004; 42(11):5302-8. · 4.15 Impact Factor
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ABSTRACT: Currently the need for various developmental models in material sciences to develop green technologies has been reemphasized. For biodiversity rich countries like India, low investment and sustainability of biological synthesis adds to its attraction. Plants respond to heavy metal stress by metal complexation process like production of phyochelations or by other metal chelating peptides. In this paper we report the synthesis of AgNPS from the room dried stem and root of Ocimum sanctum at room temperature. The reaction process was simple for formation of highly stable silver nanoparticles. The morphology and crystalline phase of the NPs were determined from transmission electronmicroscopy (TEM), selected area electron diffraction (SAED) and X-ray diffraction(XRD) spectra. Transmission Electron Microscopy studies showed that the average silver nanoparticles obtained from roots and stem were of sizes 10 ± 2 nm and 5 ± 1.5 nm respectively.
MEMS, NANO, and Smart Systems, International Conference on.
