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

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.

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-001831nas a2200229 4500008004100000022001400041245006500055210006500120260009500185300001400280490000600294520104900300653001701349653001701366653002301383100002101406700002101427700001401448700002101462700001901483856009901502 2007 eng d a1533-488000aBacterial enzyme mediated biosynthesis of gold nanoparticles0 aBacterial enzyme mediated biosynthesis of gold nanoparticles a25650 NORTH LEWIS WAY, STEVENSON RANCH, CA 91381-1439 USAbAMER SCIENTIFIC PUBLISHERScDEC a4369-43770 v73 a

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.

10aBiosynthesis10abovine serum10agold nanoparticles1 aBharde, Atul, A.1 aKulkarni, Aarohi1 aRao, Mala1 aPrabhune, Asmita1 aSastry, Murali uhttps://library.ncl.res.in/content/bacterial-enzyme-mediated-biosynthesis-gold-nanoparticles-002718nas 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

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.

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

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.

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