@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: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 { ISI:000256975600012, title = {Extracellular synthesis of crystalline silver nanoparticles and molecular evidence of silver resistance from morganella sp.: towards understanding biochemical synthesis mechanism}, journal = {ChemBioChem}, volume = {9}, number = {9}, year = {2008}, month = {JUN}, pages = {1415-1422}, publisher = {WILEY-V C H VERLAG GMBH}, type = {Article}, address = {PO BOX 10 11 61, D-69451 WEINHEIM, GERMANY}, abstract = {

There has been significant progress in the biological synthesis of nanomaterials. However, the molecular mechanism of synthesis of such bio-nanomaterials remains largely unknown. Here, we report the extracellular synthesis of crystalline silver nanoparticles (AgNPs) by using Morganella sp., and show molecular evidence I of silver resistance by elucidating the synthesis mechanism. The AgNPs were 20 +/- 5 nm in diameter and were highly stable at 1 room temperature. The kinetics of AgNPs formation was investigated. Detectable particles were formed after on hour of reaction, and their production remained exponential up to 18 h, and saturated at 24 h. Morganella sp. was found to be highly resistant to silver cations and was able to grow in the presence of more than 0.5 mm AgNO3. Three gene homologues viz. silE, silP and silS were identified in silver-resistant Morganella sp. The homologue of silE from Morganella sp. showed 99\% nucleotide sequence similarity with the previously reported gene, silE, which encodes a periplasmic silver-binding protein. The homologues of silP and silS were also highly similar to previously reported sequences. Similar activity was totally absent in closely related Escherichia coli; this suggests that a unique mechanism of extracellular AgNPs synthesis is associated with silver-resistant Morganella sp. The molecular mechanism of silver resistance and its gene products might have a key role to play in the overall synthesis process of AgNPs by Morganella sp. An understanding of such biochemical mechanisms at the molecular level might help in developing an ecologically friendly and cost-effective protocol for microbial AgNPs synthesis.

}, keywords = {Biosynthesis, Morganella sp., Nanoparticles, sil gene homologues, Silver}, issn = {1439-4227}, doi = {10.1002/cbic.200700592}, author = {Parikh, Rasesh Y. and Singh, Sanjay and Bhagavatula L. V. Prasad and Patole, Milind S. and Sastry, Murali and Shouche, Yogesh S.} }