@article { ISI:000233129500064, title = {Biocompatibility of gold nanoparticles and their endocytotic fate inside the cellular compartment: a microscopic overview}, journal = {Langmuir}, volume = {21}, number = {23}, year = {2005}, month = {NOV}, pages = {10644-10654}, publisher = {AMER CHEMICAL SOC}, type = {Article}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Macrophages are one of the principal immune effector cells that play essential roles as secretory, phagocytic, and antigen-presenting cells in the immune system. In this study, we address the issue of cytotoxicity and immunogenic effects of gold nanoparticles on RAW264.7 macrophage cells. The cytotoxicity of gold nanoparticles has been correlated with a detailed study of their endocytotic uptake using various microscopy tools such as atomic force microscopy (AFM), confocal-laser-scanning microscopy (CFLSM), and transmission electron microscopy (TEM). Our findings suggest that Au(0) nanoparticles are not cytotoxic, reduce the production of reactive oxygen and nitrite species, and do not elicit secretion of proinflammatory cytokines TNF-alpha and IL1-, making them suitable candidates for nanomedicine. AFM measurements suggest that gold nanoparticles are internalized inside the cell via a mechanism involving pinocytosis, while CFLSM and TEM studies indicate their internalization in lysosomal bodies arranged in perinuclear fashion. Our studies thus underline the noncytotoxic, nonimmunogenic, and biocompatible properties ofgold nanoparticles with the potential for application in nanoimmunology, nanomedicine, and nanobiotechnology.

}, issn = {0743-7463}, doi = {10.1021/la0513712}, author = {Shukla, Ravi and Bansal, Vipul and Chaudhary, Manakshi and Basu, Atanu and Bhonde, Ramesh R. and Sastry, Murali} } @article { ISI:000228418700023, title = {Bioleaching of sand by the fungus fusarium oxysporum as a means of producing extracellular silica nanoparticles}, journal = {Advanced Materials}, volume = {17}, number = {7}, year = {2005}, month = {APR}, pages = {889+}, publisher = {WILEY-V C H VERLAG GMBH}, type = {Article}, address = {PO BOX 10 11 61, D-69451 WEINHEIM, GERMANY}, abstract = {

A plant pathogenic fungus, Fusarium oxysporum, can be used as a biological model system for the extracellular bioleaching of hollow spherical silica nanoparticles (see Figure) from sand. The room-temperature synthesis of oxide nanomaterials using microorganisms starting from potential waste materials could lead to eco-friendly and economically viable methods for the large-scale synthesis of nanomaterials.

}, issn = {0935-9648}, doi = {10.1002/adma.200401176}, author = {Bansal, Vipul and Sanyal, A. and Rautaray, D. and Ahmad, Absar and Sastry, Murali} } @article { ISI:000252511300020, title = {Bacterial enzyme mediated biosynthesis of gold nanoparticles}, journal = {Journal of Nanoscience and Nanotechnology}, volume = {7}, number = {12}, year = {2007}, month = {DEC}, pages = {4369-4377}, publisher = {AMER SCIENTIFIC PUBLISHERS}, type = {Article}, address = {25650 NORTH LEWIS WAY, STEVENSON RANCH, CA 91381-1439 USA}, abstract = {

Development of synthesis methods for anisotropic metal nanoparticles is of considerable interest due to their remarkable optoelectronic properties. Various shapes ranging from rods to cubes to tetrapods and prisms may be obtained by chemical methods. Here we show that anisotropic gold nanoparticles can be synthesized biologically by the bacterium Actinobacter spp. when challenged with gold chloride in the presence of Bovine serum albumin (BSA). We also observed that synthesis of gold nanoparticles occur with simultaneous induction of the protease enzyme secreted by the bacterium in the presence of BSA. The presence of BSA helps to enhance the rate of gold nanoparticles biosynthesis and may also impart some shape control. Controlling simple experimental conditions like incubation temperature and presence or absence of oxygen have drastic effect on the reaction rate and the morphology of the particles. Various assay experiments show that the presence of enzyme protease can act as a reducing as well as shape directing agent.

}, keywords = {Biosynthesis, bovine serum, gold nanoparticles}, issn = {1533-4880}, doi = {10.1166/jnn.2007.891}, author = {Bharde, Atul A. and Kulkarni, Aarohi and Rao, Mala and Prabhune, Asmita and Sastry, Murali} } @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} }