@article { ISI:000230220900008, title = {Bacterial aerobic synthesis of nanocrystalline magnetite}, journal = {Journal of the American Chemical Society}, volume = {127}, number = {26}, year = {2005}, month = {JUL}, pages = {9326-9327}, publisher = {AMER CHEMICAL SOC}, type = {Article}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, issn = {0002-7863}, doi = {10.1021/ja0508469}, author = {Bharde, Atul A. and Wani, A. and Shouche, Y. and Joy, Pattayil Alias and Bhagavatula L. V. Prasad and Sastry, M.} } @article { ISI:000257271600057, title = {Bacterial synthesis of copper/copper oxide nanoparticles}, journal = {Journal of Nanoscience and Nanotechnology}, volume = {8}, number = {6}, year = {2008}, month = {JUN}, pages = {3191-3196}, publisher = {AMER SCIENTIFIC PUBLISHERS}, type = {Article}, address = {26650 THE OLD RD, STE 208, VALENCIA, CA 91381-0751 USA}, abstract = {

A bacterial mediated synthesis of copper/copper oxide nanoparticle composite is reported. A Gram-negative bacterium belonging to the genus Serratia was isolated from the midgut of Stibara sp., an insect of the Cerambycidae family of beetles found in the Northwestern Ghats of India. This is a unique bacterium that is quite specific for the synthesis of copper oxide nanoparticles as several other strains isolated from the same insect and common Indian mosquitoes did not result in nanoparticle formation. By following the reaction systematically, we could delineate that the nanoparticle formation occurs intracellularly. However, the process results in the killing of bacterial cells. Subsequently the nanoparticles leak out as the cell wall disintegrates. The nanoparticles formed are thoroughly characterized by UV-Vis, TEM, XRD, XPS and FTIR studies.

}, keywords = {bacterial synthesis, Nanoparticles, TEM, XPS, XRD}, issn = {1533-4880}, doi = {10.1166/jnn.2008.095}, author = {Hasan, Syed Saif and Singh, Sanjay and Parikh, Rasesh Y. and Dharne, Mahesh S. and Patole, Milind S. and Bhagavatula L. V. Prasad and Shouche, Yogesh S.} } @article { ISI:000256073500012, title = {Bacterial synthesis of silicon/silica nanocomposites}, journal = {Journal of Materials Chemistry}, volume = {18}, number = {22}, year = {2008}, month = {APR}, pages = {2601-2606}, publisher = {ROYAL SOC CHEMISTRY}, type = {Article}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

The synthesis of silicon/silica nanoparticle composites by the bacterium Actinobacter sp. is demonstrated. More specifically, the formation of silicon/silica nanocomposite is shown to occur when the bacterium is exposed to K(2)SiF(6) precursor under ambient conditions. Based on the earlier reports where this bacterium has been shown to synthesize iron oxide and iron sulfide nanoparticles, it is hypothesized that this bacterium secretes reductases and oxidising enzymes, which lead to the Si/SiO(2) nanocomposite synthesis. The particles obtained by bacterial synthesis were thoroughly characterized. The cytotoxicity studies revealed that the particles do not display any cytotoxicity to human skin cells. The synthesis of silica nanoparticles by bacteria in the present study demonstrates the versatility of the organism, and the formation of elemental silicon by this environmentally friendly process expands further the scope of microorganism based nanomaterial synthesis.

}, issn = {0959-9428}, doi = {10.1039/b719528a}, author = {Singh, Sanjay and Bhatta, Umananda M. and Satyam, P. V. and Dhawan, Alok and Sastry, Murali and Bhagavatula L. V. Prasad} } @article { ISI:000256232900024, title = {Bacteria-mediated precursor-dependent biosynthesis of superparamagnetic iron oxide and iron sulfide nanoparticles}, journal = {Langmuir}, volume = {24}, number = {11}, year = {2008}, month = {JUN}, pages = {5787-5794}, publisher = {AMER CHEMICAL SOC}, type = {Article}, chapter = { }, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

The bacterium Actinobacter sp. has been shown to be capable of extracellularly synthesizing iron based magnetic nanoparticles, namely maghemite (gamma-Fe2O3) and greigite (Fe3S4) Under ambient conditions depending on the nature of precursors used. More precisely, the bacterium synthesized maghemite when reacted with ferric chloride and iron sulfide when exposed to the aqueous solution of ferric chloride-ferrous sulfate. Challenging the bacterium with different metal ions resulted in induction of different proteins, which bring about the specific biochemical transformations in each case leading to the observed products. Maghemite and iron sulfide nanoparticles show superparamagnetic characteristics as expected. Compared to the earlier reports of magnetite and greigite synthesis by magnetotactic bacteria and iron reducing bacteria, which take place strictly under anaerobic conditions, the present procedure offers significant advancement since the reaction occurs under aerobic condition. Moreover, reaction end products can be tuned by the choice of precursors used.

}, issn = {0743-7463}, doi = {10.1021/la704019p}, author = {Bharde, Atul A. and Parikh, Rasesh Y. and Baidakova, Marina and Jouen, Samuel and Hannoyer, Beatrice and Enoki, Toshiaki and Bhagavatula L. V. Prasad and Shouche, Yogesh S. and Ogale, Satishchandra B. and Sastry, Murali} } @article {42680, title = {Bacterial synthesis of phtocatalytically active and biocompatible TiO2 and ZnO nanoparticles}, journal = {International Journal of Green Nanotechnology: Physics and Chemistry}, volume = {2}, year = {2010}, month = {DEC}, pages = {80-99}, abstract = {

TiO2 and ZnO nanoparticles are well known for their photocatalytic and ultraviolet (UV)-absorbent properties and have successfully entered into the market as consumer products. Large volume production of these nanoparticles by industries require environmentally friendly processes of synthesis. In this article, we show that when challenged with an appropriate precursor, the bacterium Actinobacter spp. can lead to the extracellular synthesis of ZnO and TiO2 nanoparticles. The biological way of synthesizing these materials probably leads to the in situ doping of elements like C, F, and N into their crystal lattices, which is evidenced by a red shift in the absorption edge. Because the doping is expected to affect the photocatalytic activity of these materials under different light conditions, such investigations have also been undertaken here. Further, the biocompatibility of these nanomaterials (cytotoxicity and genotoxicity) has also been investigated in detail.

}, keywords = {Biosynthesis, genotoxicity, Nanoparticles, Nanotoxicity, Photocatalysis}, doi = {10.1080/19430876.2010.532459}, author = {Singh, Sanjay and Britto, Virginia D. and Bharde, Atul A. and Sastry, Murali and Dhawan, Alok and Bhagavatula L. V. Prasad} } @article { ISI:000293587300003, title = {Biocompatible gellan gum-reduced gold nanoparticles: cellular uptake and subacute oral toxicity studies}, journal = {Journal of Applied Toxicology}, volume = {31}, number = {5}, year = {2011}, month = {JUL}, pages = {411-420}, publisher = {WILEY-BLACKWELL}, address = {COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA}, abstract = {

Currently gold nanoparticles are being explored for drug delivery and other biomedical applications; therefore it is necessary to study the fate of such nanoparticles inside the body. The objective of the present study was to investigate the cellular uptake and toxicity of the gold nanoparticles synthesized using a microbial polysaccharide, gellan gum, as a capping and reducing agent. The cellular uptake of gold nanoparticles was studied on mouse embryonic fibroblast cells, NIH3T3 and human glioma cell line, LN-229. The cellular uptake study indicated that the gellan gum-reduced gold nanoparticles were located in cancer cells (LN-229) while no uptake was observed in normal mouse embryonic fibroblast cells (NIH3T3). The toxicity of the gold nanoparticles was evaluated by carrying out subacute 28 day oral toxicity studies in rats. Subacute administration of gum-reduced gold nanoparticles to the rats did not show any hematological or biochemical abnormalities. The weight and normal architecture of various organs did not change compared with control. The current findings, while establishing the specific uptake of nanoparticles into cancerous cells, also demonstrates that the gellan gum-reduced gold nanoparticles are devoid of toxicity in animals following oral administration. Copyright (c) 2010 John Wiley \& Sons, Ltd.

}, keywords = {cell lines, cellular uptake, Gellan gum, gold nanoparticles, subacute toxicity}, issn = {0260-437X}, doi = {10.1002/jat.1595}, author = {Dhar, Sheetal and Mali, Vishal and Bodhankar, Subhash L. and Shiras, Anjali and Bhagavatula L. V. Prasad and Pokharkar, Varsha} } @article {42668, title = {Bromide ion mediated modification to digestive ripening process: preparation of ultra-small Pd, Pt, Rh and Ru nanoparticles}, journal = {Nano Research}, volume = {9}, year = {2016}, month = {MAY}, pages = {2007{\textendash}2017}, abstract = {

Nanoparticles of catalytically important transition metals, such as Pd, Pt, Rh, and Ru have been prepared by the well-known {\textquotedblleft}digestive ripening{\textquotedblright} (DR) and {\textquotedblleft}modified digestive ripening{\textquotedblright} (mDR) methods. In the traditional DR process, a polydisperse colloidal dispersion is refluxed in the presence of a surface-active molecule, such as alkanethiol. The mDR method involved a small modification in the procedure, wherein refluxing was performed with an alkanethiol and a tetra-alkylammonium bromide surfactant. This minor modification led to a dramatic change in the final particle size distributions, giving access to nanoparticles in the \<3 nm size regime; this was not possible with the traditional DR process. Bromide ions, which are present during refluxing, proved to be an important ingredient in the modification process. These bromide ions are revealed to act as etchants, resulting in ultra-small nanoparticles. All transition metal nanoparticles investigated displayed catalytic activity in the reduction reaction of p-nitro phenol. Pd nanoparticles, synthesized by a modified digestive ripening method, exhibited the best catalytic activity among the systems investigated.

}, doi = {10.1007/s12274-016-1091-0}, author = {Seth, Jhumur and Bhagavatula L. V. Prasad} }