02201nas a2200265   4500008004100000022001400041245010700055210006900162260009500231300001000326490000600336520126700342653001701609653001201626653001101638653000901649653002301658653001801681100001701699700002501716700002601741700001701767700001901784856013201803       2005                        eng d  a1550-703300aExtra-/intracellular biosynthesis of gold nanoparticles by an alkalotolerant fungus, trichothecium sp.0 aExtraintracellular biosynthesis of gold nanoparticles by an alka  a25650 NORTH LEWIS WAY, STEVENSON RANCH, CA 91381-1439 USAbAMER SCIENTIFIC PUBLISHERScMAR  a47-530 v13 a<p>The development of reliable, eco-friendly processes for the synthesis of nanoscale materials is an important aspect of nanotechnology. As part of our ongoing investigation into the use of fungi for nanoparticle synthesis, we report herein that depending on the reaction conditions of the fungus Trichothecium sp. with aqueous gold ions, gold nanoparticle synthesis can be controlled to occur either within the biomass or extracellularly. Moreover, we have found that reaction of gold ions with the Trichothecium sp. fungal biomass under stationary conditions results in the rapid extracellular formation of gold nanoparticles of spherical, rod-like and triangular morphology whereas reaction of the biomass under shaking conditions resulted in intracellular growth of the nanoparticles. It is believed that on changing the reaction conditions of the fungus with gold ions, the enzymes and proteins which are being released into the medium under stationary conditions do not get released under shaking conditions resulting in the formation of extracellular or intracellular gold nanoparticles respectively. The gold nanoparticles are not toxic to the cells and the cells continued to grow after the biosynthesis of the gold nanoparticles in both the cases.</p>10aBiosynthesis10aenzymes10aFungus10aGold10aMorphology Control10aNanoparticles1 aAhmad, Absar1 aSenapati, Satyajyoti1 aKhan, Mohammad, Islam1 aKumar, Rajiv1 aSastry, Murali  uhttps://library.ncl.res.in/content/extra-intracellular-biosynthesis-gold-nanoparticles-alkalotolerant-fungus-trichothecium-sp-002031nas a2200229   4500008004100000022001400041245013900055210006900194260007700263300001200340490000600352520119500358653001801553653000901571653001801580653001201598653001601610100001601626700001901642700001901661856012101680       2007                        eng d  a1613-681000aSpider silk as an active scaffold in the assembly of gold nanoparticles and application of the gold-silk bioconjugate in vapor sensing0 aSpider silk as an active scaffold in the assembly of gold nanopa  aPO BOX 10 11 61, D-69451 WEINHEIM, GERMANYbWILEY-V C H VERLAG GMBHcMAR  a466-4730 v33 a<p>Spider silk is being viewed with interest by materials scientists due to its excellent resilience and mechanical properties. In this paper we show that spider silk is an excellent scaffold for the one-step synthesis and assembly of gold nanoparticles. Formation of a gold nanoparticle-spider-silk bioconjugate material is accomplished by simple reaction of the fibers with aqueous chloroauric acid. The gold nanoparticles thus formed are strongly bound to the spider-silk fiber surface enabling study of the electrical properties of the nano bioconjugate. Using the well-known contraction/expansion behavior of the fibers in solvents of varying polarity, we show that exposure of the gold nanoparticle-spider silk bioconjugate to vapors of methanol and chloroform leads to changes in electrical transport through the nanoparticles and thus, the possibility of developing a vapor sensor. The bioconjugate shows excellent response time and cycling efficiency to methanol vapors. The activation energy of electron transport from one gold nanoparticle to another in the nanobiocojugate was determined from temperature-dependent electron-transport measurements to be approximately 1.7 eV.</p>10abioconjugates10aGold10aNanoparticles10asensors10aspider silk1 aSingh, Amit1 aHede, Shantesh1 aSastry, Murali  uhttps://library.ncl.res.in/content/spider-silk-active-scaffold-assembly-gold-nanoparticles-and-application-gold-silk02718nas a2200265   4500008004100000022001400041245018300055210006900238260007700307300001400384490000600398520169400404653001702098653001902115653001802134653002402152653001102176100002302187700001802210700003002228700002302258700001902281700002402300856012802324       2008                        eng d  a1439-422700aExtracellular synthesis of crystalline silver nanoparticles and molecular evidence of silver resistance from morganella sp.: towards understanding biochemical synthesis mechanism0 aExtracellular synthesis of crystalline silver nanoparticles and   aPO BOX 10 11 61, D-69451 WEINHEIM, GERMANYbWILEY-V C H VERLAG GMBHcJUN  a1415-14220 v93 a<p>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.</p>10aBiosynthesis10aMorganella sp.10aNanoparticles10asil gene homologues10aSilver1 aParikh, Rasesh, Y.1 aSingh, Sanjay1 aPrasad, Bhagavatula L. V.1 aPatole, Milind, S.1 aSastry, Murali1 aShouche, Yogesh, S.  uhttps://library.ncl.res.in/content/extracellular-synthesis-crystalline-silver-nanoparticles-and-molecular-evidence-silver-001819nas a2200253   4500008004100000245009700041210006900138260000800207300001000215490000600225520098700231653001701218653001701235653001801252653001701270653001901287100001801306700002501324700002101349700001901370700001701389700003001406856012901436       2010                        eng d00aBacterial synthesis of phtocatalytically active and biocompatible TiO2 and ZnO nanoparticles0 aBacterial synthesis of phtocatalytically active and biocompatibl  cDEC  a80-990 v23 a<p>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.</p>10aBiosynthesis10agenotoxicity10aNanoparticles10aNanotoxicity10aPhotocatalysis1 aSingh, Sanjay1 aBritto, Virginia, D.1 aBharde, Atul, A.1 aSastry, Murali1 aDhawan, Alok1 aPrasad, Bhagavatula L. V.  uhttps://library.ncl.res.in/content/bacterial-synthesis-phtocatalytically-active-and-biocompatible-tio2-and-zno-nanoparticles