02056nas a2200205 4500008004100000022001400041245012600055210006900181260007100250300001600321490000700337520125700344100001701601700001801618700002401636700001601660700002301676700001901699856013201718 2005 eng d a0743-746300aBiocompatibility of gold nanoparticles and their endocytotic fate inside the cellular compartment: a microscopic overview0 aBiocompatibility of gold nanoparticles and their endocytotic fat a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcNOV a10644-106540 v213 a

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.

1 aShukla, Ravi1 aBansal, Vipul1 aChaudhary, Manakshi1 aBasu, Atanu1 aBhonde, Ramesh, R.1 aSastry, Murali uhttps://library.ncl.res.in/content/biocompatibility-gold-nanoparticles-and-their-endocytotic-fate-inside-cellular-compartment-001154nas a2200193 4500008004100000022001400041245011600055210006900171260007700240300000900317490000700326520042000333100001800753700001500771700001700786700001700803700001900820856012100839 2005 eng d a0935-964800aBioleaching of sand by the fungus fusarium oxysporum as a means of producing extracellular silica nanoparticles0 aBioleaching of sand by the fungus fusarium oxysporum as a means  aPO BOX 10 11 61, D-69451 WEINHEIM, GERMANYbWILEY-V C H VERLAG GMBHcAPR a889+0 v173 a

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.

1 aBansal, Vipul1 aSanyal, A.1 aRautaray, D.1 aAhmad, Absar1 aSastry, Murali uhttps://library.ncl.res.in/content/bioleaching-sand-fungus-fusarium-oxysporum-means-producing-extracellular-silica-002201nas 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-001498nas a2200217 4500008004100000022001400041245006500055210006400120260011000184300001400294490000700308520073800315100001801053700001701071700002101088700002101109700001501130700001701145700001901162856009901181 2005 eng d a0959-942800aFungus-mediated biosynthesis of silica and titania particles0 aFungusmediated biosynthesis of silica and titania particles aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcMAY a2583-25890 v153 a

The synthesis of inorganic materials by biological systems is characterized by processes that occur at close to ambient temperatures, pressures and neutral pH. This is exemplified by biosilicification in marine organisms such as diatoms while laboratory-based synthesis of silica involves extreme temperature and pH conditions. We show here that silica and titania particles may be produced by challenging the fungus Fusarium oxysporum with aqueous anionic complexes SiF62- and TiF62- respectively. Extra-cellular protein-mediated hydrolysis of the anionic complexes results in the facile room temperature synthesis of crystalline titania particles while calcination at 300 degrees C is required for crystallization of silica.

1 aBansal, Vipul1 aRautaray, D.1 aBharde, Atul, A.1 aAhire, Kedar, C.1 aSanyal, A.1 aAhmad, Absar1 aSastry, Murali uhttps://library.ncl.res.in/content/fungus-mediated-biosynthesis-silica-and-titania-particles-001649nas a2200193 4500008004100000022001400041245010400055210006900159260007100228300001400299490000700313520092400320100001501244700001701259700001801276700001701294700001901311856012501330 2005 eng d a0743-746300aHeavy-metal remediation by a fungus as a means of production of lead and cadmium carbonate crystals0 aHeavymetal remediation by a fungus as a means of production of l a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcAUG a7220-72240 v213 a

We show here that reaction of the fungus, Fusarium oxysporum, with the aqueous heavy-metal ions Pb2+ and Cd2+ results in the one-step formation of the corresponding metal carbonates. The metal carbonates are formed by reaction of the heavy-metal ions with CO2 produced by the fungus during metabolism and thus provide a completely biological method for production of crystals of metal carbonates. The PbCO3 and CdCO3 crystals thus produced have interesting morphologies that are shown to arise because of interaction of the growing crystals with specific proteins secreted by the fungus during reaction. An additional advantage of this approach is that the reaction leads to detoxification of the aqueous solution and could have immense potential for bioremediation of heavy metals. Under conditions of this study, the metal ions are not toxic to the fungus, which readily grows after exposure to the metal ions.

1 aSanyal, A.1 aRautaray, D.1 aBansal, Vipul1 aAhmad, Absar1 aSastry, Murali uhttps://library.ncl.res.in/content/heavy-metal-remediation-fungus-means-production-lead-and-cadmium-carbonate-crystals-001651nas a2200217 4500008004100000022001400041245011700055210006900172260007100241300001400312490000700326520083500333100002001168700002001188700002101208700002301229700001501252700001901267700001901286856012801305 2005 eng d a0897-475600aPorous gold nanospheres by controlled transmetalation reaction: a novel material for application in cell imaging0 aPorous gold nanospheres by controlled transmetalation reaction a a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcOCT a5000-50050 v173 a

Hollow shell nanostructures have numerous potential applications due to their interesting optical and electronic properties, which can be tuned by varying their shape, size, and shell thickness. In this paper we describe a simple galvanic replacement reaction (transmetalation reaction) involving sacrificial silver nanoparticles and Au(III) ions using a dialysis membrane. The dialysis membrane acts as a partial barrier that provides excellent control over the kinetics of reaction. This process results in the formation of porous gold nanospheres that improve the fluorescence in cell staining by offering an enhanced surface area for binding of the fluorescent dye, propidium iodide (PI). Such porous nanostructures could be ideal candidates for applications such as catalysis, enzyme immobilization, and drug delivery.

1 aShukla, Sourabh1 aPriscilla, Anie1 aBanerjee, Meenal1 aBhonde, Ramesh, R.1 aGhatak, J.1 aSatyam, P., V.1 aSastry, Murali uhttps://library.ncl.res.in/content/porous-gold-nanospheres-controlled-transmetalation-reaction-novel-material-application-001699nas a2200241 4500008004100000022001400041245007800055210006900133260009500202300001400297490000600311520088200317653001901199653000901218653001201227653001601239653001801255653002301273100002001296700001701316700001901333856010501352 2005 eng d a1533-488000aSynthesis of gold nanospheres and nanotriangles by the Turkevich approach0 aSynthesis of gold nanospheres and nanotriangles by the Turkevich a25650 NORTH LEWIS WAY, STEVENSON RANCH, CA 91381-1439 USAbAMER SCIENTIFIC PUBLISHERScOCT a1721-17270 v53 a

Gold nanoparticles of triangular morphology possess interesting optical properties with potential application in medicine and infrared absorbing coatings, however, little is known about conditions that favor their growth. In this paper, we have reinvestigated a time-tested recipe for the formation of gold nanospheres by citrate reduction of aqueous gold ions under boiling conditions (Turkevich recipe). Our principle findings are that gold nanotriangle formation is kinetically controlled and is highly favored at low temperatures. Furthermore, the presence of chloride ions from the precursor chloroaurate ions plays a major role in promoting the growth of [111] oriented triangular/truncated triangular particles. The presence of bromide and iodide ions that possess the ability to replace surface-bound chloride ions inhibits triangle formation to varying degrees.

10aCrystal growth10aGold10ahalides10ananospheres10ananotriangles10aTemperature effect1 aShankar, S., S.1 aBhargava, S.1 aSastry, Murali uhttps://library.ncl.res.in/content/synthesis-gold-nanospheres-and-nanotriangles-turkevich-approach-101952nas a2200241 4500008004100000022001400041245011200055210006900167260009500236300001400331490000600345520104000351653001301391653003201404653002101436653001901457100002001476700002301496700001801519700001901537700003001556856012401586 2006 eng d a1533-488000aAssembly of phase transferred nickel nanoparticles at air-water interface using Langmuir-Blodgett technique0 aAssembly of phase transferred nickel nanoparticles at airwater i a25650 NORTH LEWIS WAY, STEVENSON RANCH, CA 91381-1439 USAbAMER SCIENTIFIC PUBLISHERScDEC a3736-37450 v63 a

Development of simple and efficient protocol for the synthesis of Ni nanoparticles in aqueous media and their subsequent phase transfer to organic media is reported. The synthesis of nickel nanoparticles in aqueous medium is accomplished by reducing the nickel nitrate with sodium borohydricle in presence of oleic acid. It results in the formation of nickel nanoparticles capped with oleic acid. The pristine oleic acid capped nickel nanoparticles were then phase transferred to nonpolar solvents such as toluene using stearic acid. The phase transfer was effective probably due to the space exchange between the oleic acid moiety and stearic acid molecules. The hydrophobized Ni thus obtained was organized at the air-water interface and it was observed that by controlling the pressure and concentration of hydrophobized Ni nanoparticles at air-water interface, linear ribbon like assemblies could be obtained. The organization process was followed by surface pressure-area isotherm measurement and Brewster Angle Microscopy.

10aassembly10aLangmuir-Blodgett technique10aNi nanoparticles10aPhase transfer1 aBala, Tanushree1 aJoshi, Bhagyashree1 aIyer, Neelima1 aSastry, Murali1 aPrasad, Bhagavatula L. V. uhttps://library.ncl.res.in/content/assembly-phase-transferred-nickel-nanoparticles-air-water-interface-using-langmuir-001799nas a2200169 4500008004100000022001400041245013900055210006900194260008000263300001400343490000700357520107100364100001601435700002801451700001901479856013101498 2006 eng d a0957-448400aConstruction of conductive multilayer films of biogenic triangular gold nanoparticles and their application in chemical vapour sensing0 aConstruction of conductive multilayer films of biogenic triangul aDIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLANDbIOP PUBLISHING LTDcMAY a2399-24050 v173 a

Metal nanoparticles are interesting building blocks for realizing films for a number of applications that include bio- and chemical sensing. To date, spherical metal nanoparticles have been used to generate functional electrical coatings. In this paper we demonstrate the synthesis of electrically conductive coatings using biologically prepared gold nanotriangles as the building blocks. The gold nanotriangles are prepared by the reduction of aqueous chloroaurate ions using an extract of the lemongrass plant (Cymbopogon flexuosus) which are thereafter assembled onto a variety of substrates by simple solution casting. The conductivity of the film shows a drastic fall upon mild heat treatment, leading to the formation of electrically conductive thin films of nanoparticles. We have also investigated the possibility of using the gold nanotriangle films in vapour sensing. A large fall in film resistance is observed upon exposure to polar molecules such as methanol, while little change occurs upon exposure to weakly polar molecules such as chloroform.

1 aSingh, Amit1 aChaudhary, Minakshi, V.1 aSastry, Murali uhttps://library.ncl.res.in/content/construction-conductive-multilayer-films-biogenic-triangular-gold-nanoparticles-and-their-002108nas a2200169 4500008004100000022001400041245009700055210006900152260007100221300001600292490000800308520144300316100001801759700001701777700001901794856012501813 2006 eng d a0002-786300aFungus-mediated biotransformation of amorphous silica in rice husk to nanocrystalline silica0 aFungusmediated biotransformation of amorphous silica in rice hus a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcNOV a14059-140660 v1283 a

Rice husk is a cheap agro-based waste material, which harbors a substantial amount of silica in the form of amorphous hydrated silica grains. However, there have been no attempts at harnessing the enormous amount of amorphous silica present in rice husk and its room-temperature biotransformation into crystalline silica nanoparticles. In this study, we address this issue and describe how naturally deposited amorphous biosilica in rice husk can be bioleached and simultaneously biotransformed into high value crystalline silica nanoparticles. We show here that the fungus Fusarium oxysporum rapidly biotransforms the naturally occurring amorphous plant biosilica into crystalline silica and leach out silica extracellularly at room temperature in the form of 2-6 nm quasi-spherical, highly crystalline silica nanoparticles capped by stabilizing proteins; that the nanoparticles are released into solution is an advantage of this process with significant application and commercial potential. Calcination of the silica nanoparticles leads to loss of occluded protein and to an apparently porous structure often of cubic morphology. The room-temperature synthesis of oxide nanomaterials using microorganisms starting from potential cheap agro-industrial waste materials is an exciting possibility and could lead to an energy-conserving and economically viable green approach toward the large-scale synthesis of oxide nanomaterials.

1 aBansal, Vipul1 aAhmad, Absar1 aSastry, Murali uhttps://library.ncl.res.in/content/fungus-mediated-biotransformation-amorphous-silica-rice-husk-nanocrystalline-silica-001403nas a2200181 4500008004100000022001400041245008100055210006900136260007100205300002600276490000800302520072300310100001801033700001901051700001701070700001901087856011501106 2006 eng d a0002-786300aRoom-temperature biosynthesis of ferroelectric barium titanate nanoparticles0 aRoomtemperature biosynthesis of ferroelectric barium titanate na a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcSEP aArticle No. JA063011M0 v1283 a

The syntheses of inorganic materials by biological systems is characterized by processes that occur close to ambient temperatures, pressures, and neutral pH, as is exemplified by biosilicification and biomineralization processes in nature. Conversely, laboratory-based syntheses of oxide materials often require extremes of temperature and pressure. We have shown here the extracellular, room-temperature biosynthesis of 4-5 nm ternary oxide nanoparticles such as barium titanate (BT) using a fungus-mediated approach. The tetragonality as well as a lowered Curie transition temperature in sub-10 nm particles was established, and the ferroelectricity in these particles was shown using Kelvin probe microscopy.

1 aBansal, Vipul1 aPoddar, Pankaj1 aAhmad, Absar1 aSastry, Murali uhttps://library.ncl.res.in/content/room-temperature-biosynthesis-ferroelectric-barium-titanate-nanoparticles-101831nas 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-001762nas a2200205 4500008004100000022001400041245007300055210006900128260011000197300001400307490000700321520099400328100001801322700001901340700002501359700001901384700001901403700003001422856010401452 2007 eng d a0959-942800aEffect of halogen addition to monolayer protected gold nanoparticles0 aEffect of halogen addition to monolayer protected gold nanoparti aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcFEB a1614-16190 v173 a

The effects of N-halosuccinimide and halogen addition to monolayer protected gold nanoparticles (Au NPs) dispersed in organic media are described. Contrary to the expectation that nanoparticles dispersed in organic media are stable against aggregation, N-iodosuccinimide addition induced aggregation of octadecylamine capped gold nanoparticles in chloroform or toluene. It was observed that even KI and CuI addition could bring about the aggregation though they are very sparingly soluble in organic solvents. It was also found that even molecular iodine could bring about the above mentioned aggregation. Interestingly, when CuI is used the aggregated structures readily convert to very thin flat nanostructures upon exposure to an electron beam or UV irradiation. In fact when the aggregation is induced by the addition of KI or N-iodosuccinamide we do not see the flattening of the aggregated structures exemplifying the important role of Cu ions in making these flat structures.

1 aSingh, Sanjay1 aPasricha, Renu1 aBhatta, Umananda, M.1 aSatyam, P., V.1 aSastry, Murali1 aPrasad, Bhagavatula L. V. uhttps://library.ncl.res.in/content/effect-halogen-addition-monolayer-protected-gold-nanoparticles-003077nas a2200181 4500008004100000245008900041210006900130260000800199300001600207490000800223520242800231100002002659700003002679700001902709700003002728700002402758856011302782 2007 eng d00aInteraction of different metal ions with carboxylic acid group: a quantitative study0 aInteraction of different metal ions with carboxylic acid group a cJUN a6183–61900 v1113 a

The binding strength of the carboxylic acid group (-COOH) with different divalent metal ions displays considerable variation in arachidic acid (AA) thin films. It is considered that in AA thin films the metal ions straddle the hydrophilic regions of the stacked bilayers of AA molecules via formation of carboxylates. In this study first the uptake of different divalent cations in films of AA is estimated by atomic absorption spectroscopy (AAS). Through the amount of cation uptake, it is found that the strength of binding of different cations varies as Ca2+ > Co2+ > Pb2+ > Cd2+. Variation in the binding strength of different ions is also manifested in experiments where AA thin films are exposed to metal ion mixtures. The higher binding strength of AA with certain metal ions when exposed individually, as well as the preference over the other metal ions when exposed to mixtures, reveal some interesting deviation from the expected behavior based on considerations of ionic radii. For example, Pb2+ is always found to bind to AA much more strongly than Cd2+ even though the latter has smaller ionic radius, indicating that other factors also play an important role in governing the binding strength trends apart from the effects of ionic radii. Then, to get a more meaningful knowledge regarding the binding capability, first-principles calculations based on density functional theory have been applied to study the interaction of different cations with the simplest carboxylic acid, acetic acid, that can result in formation of metal diacetates. Their electronic and molecular structures, cohesive energies, and stiffness of the local potential energy well at the cation (M) site are determined and attempts are made to understand the diversity in geometry and the properties of binding of different metal ions with -COOH group. We find that the calculated M−O bond energies depend sensitively on the chemistry of M atom and follow the experimentally observed trends quite accurately. The trends in M−O bond energies and hence the total M−acetate binding energy trends can actually be related to their molecular structures that fall into different categories:  Ca and Cd have tetrahedral coordination; Fe, Ni, and Co exhibit planar 4-fold coordination; and Pb is off-centered from the planar structure (forming pyramidal structure) due to its stereochemically active lone pair of electrons.

1 aBala, Tanushree1 aPrasad, Bhagavatula L. V.1 aSastry, Murali1 aKahaly, Mousumi, Upadhyay1 aWaghmare, Umesh, V. uhttps://library.ncl.res.in/content/interaction-different-metal-ions-carboxylic-acid-group-quantitative-study02499nas a2200205 4500008004100000022001400041245012900055210006900184260007300253300001400326490000800340520166300348653001902011653004002030100001902070700002802089700001902117700002602136856013102162 2007 eng d a0169-433200aScanning tunneling microscopy/spectroscopy on Au nanoparticles assembled using lauryl amine (LAM) and octadecane thiol (ODT)0 aScanning tunneling microscopyspectroscopy on Au nanoparticles as aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcMAR a5109-51150 v2533 a

In this report, we demonstrate scanning tunneling microscopy and spectroscopy on thin filins of lauryl amine (LAM) and octadecane thiol (ODT) protected gold nanoparticles. We show that the zero current in the I-V curves (measure of Coulomb blockade (CB) of the nanoparticles) depends on the properties of the spacer molecule. In both the cases the gap voltage and the tunneling current at which the images are obtained are quite different which is further confirmed from the fitting performed based on the orthodox theory. The values for the capacitance and charging energy obtained from the fitting for ODT capped particles are comparable to the values obtained using spherical capacitor model. In contrast, values of these parameters were found to differ for LAM capped nanoparticles. While imaging, ODT capped nanoparticles were observed to drag along the scan direction leading to ordering of particles. Images of LAM capped gold nanoparticles show local ordering in self-assembly of particles although no evidence of large scale ordering in spatial Fourier transform was seen. These observations suggest that nanoparticles with larger CB would be intaged nonevasively in contrast to small CB systems for which tip induced effects will be dominant. In both the systems the current was found to rise faster than theoretical curves based on the orthodox theory suggesting that mechanism of charge transfer in this case may involve field emission rather than tunneling through a rectangular barrier. An attempt has been made to explain charge transfer based on Fowler-Nordheim (F-N) plots of the I-V curves. (c) 2006 Elsevier B.V All rights reserved.

10aNanostructures10ascanning tunneling microscopy (STM)1 aDatar, Suwarna1 aChaudhary, Minakshi, V.1 aSastry, Murali1 aDharmadhikari, C., V. uhttps://library.ncl.res.in/content/scanning-tunneling-microscopyspectroscopy-au-nanoparticles-assembled-using-lauryl-amine-lam02031nas 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

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.

10abioconjugates10aGold10aNanoparticles10asensors10aspider silk1 aSingh, Amit1 aHede, Shantesh1 aSastry, Murali uhttps://library.ncl.res.in/content/spider-silk-active-scaffold-assembly-gold-nanoparticles-and-application-gold-silk01768nas a2200193 4500008004100000022001400041245009000055210006900145260007100214300001400285490000700299520105500306100001801361700001501379700002801394700001701422700001901439856011601458 2007 eng d a0743-746300aZirconia enrichment in zircon sand by selective fungus-mediated bioleaching of silica0 aZirconia enrichment in zircon sand by selective fungusmediated b a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcAPR a4993-49980 v233 a

One of the important routes for the production of zirconia is by chemical treatment and removal of silica from zircon sand (ZrSixOy). We present here a completely green chemistry approach toward enrichment of zirconia in zircon sand; this is based on the reaction of the fungus Fusarium oxysporum with zircon sand by a process of selective extracellular bioleaching of silica nanoparticles. Since this reaction does not result in zirconia being simultaneously leached out from the sand, there is a consequent enrichment of the zirconia component in zircon sand. We believe that fungal enzymes specifically hydrolyze the silicates present in the sand to form silicic acid, which on condensation by certain other fungal enzymes results in room-temperature synthesis of silica nanoparticles. This fungus-mediated twofold approach might have vast commercial implications in low-cost, ecofriendly, room-temperature syntheses of technologically important oxide nanomaterials from potentially cheap naturally available raw materials like zircon sand.

1 aBansal, Vipul1 aSyed, Asad1 aBhargava, Suresh, Kumar1 aAhmad, Absar1 aSastry, Murali uhttps://library.ncl.res.in/content/zirconia-enrichment-zircon-sand-selective-fungus-mediated-bioleaching-silica01714nas a2200205 4500008004100000022001400041245005700055210005600112260011000168300001400278490000700292520099100299100001801290700002501308700001901333700001701352700001901369700003001388856009001418 2008 eng d a0959-942800aBacterial synthesis of silicon/silica nanocomposites0 aBacterial synthesis of siliconsilica nanocomposites aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcAPR a2601-26060 v183 a

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.

1 aSingh, Sanjay1 aBhatta, Umananda, M.1 aSatyam, P., V.1 aDhawan, Alok1 aSastry, Murali1 aPrasad, Bhagavatula L. V. uhttps://library.ncl.res.in/content/bacterial-synthesis-siliconsilica-nanocomposites-002037nas a2200253 4500008004100000022001400041245011800055210006900173260007100242300001400313490000700327520109000334100002101424700002301445700002201468700001801490700002301508700002001531700003001551700002401581700002901605700001901634856013001653 2008 eng d a0743-746300aBacteria-mediated precursor-dependent biosynthesis of superparamagnetic iron oxide and iron sulfide nanoparticles0 aBacteriamediated precursordependent biosynthesis of superparamag a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcJUN a5787-57940 v243 a

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.

1 aBharde, Atul, A.1 aParikh, Rasesh, Y.1 aBaidakova, Marina1 aJouen, Samuel1 aHannoyer, Beatrice1 aEnoki, Toshiaki1 aPrasad, Bhagavatula L. V.1 aShouche, Yogesh, S.1 aOgale, Satishchandra, B.1 aSastry, Murali uhttps://library.ncl.res.in/content/bacteria-mediated-precursor-dependent-biosynthesis-superparamagnetic-iron-oxide-and-iron-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-001499nas a2200241 4500008004100000022001400041245010300055210006900158260005700227300001200284490000700296520062200303653000800925653003100933653003400964653001700998100002001015700002101035700002701056700001901083700002601102856012901128 2008 eng d a0250-470700aNew approach towards imaging lambda-DNA using scanning tunneling microscopy/spectroscopy (STM/STS)0 aNew approach towards imaging lambdaDNA using scanning tunneling  a233 SPRING ST, NEW YORK, NY 10013 USAbSPRINGERcJUN a309-3120 v313 a

A new methodology to anchor A-DNA to silanized n-Si(111) surface using Langmuir Blodget trough was developed. The n-Si (111) was silanized by treating it with low molecular weight octyltrichlorosilane in toluene. Scanning tunneling microscopy (STM) image of lambda-DNA on octyltrichlorosilane deposited Si substrate shows areas exhibiting arrayed structures of 700 nm length and 40 nm spacing. Scanning tunneling spectroscopy (STS) at different stages depict a broad distribution of defect states in the bandgap region of n-Si(111) which presumably facilitates tunneling through otherwise insulating DNA layer.

10aDNA10aLangmuir Blodget technique10aScanning tunneling microscopy10asilanization1 aDey, Shirshendu1 aPethkar, Sushama1 aAdyanthaya, Suguna, D.1 aSastry, Murali1 aDharmadhikari, C., V. uhttps://library.ncl.res.in/content/new-approach-towards-imaging-lambda-dna-using-scanning-tunneling-microscopyspectroscopy-001837nas a2200265 4500008004100000022001400041245010700055210006900162260009500231300001400326490000600340520085700346653002501203653003001228653001301258653002501271653002601296653002501322653002101347653002101368100002001389700001901409700001901428856012401447 2009 eng d a1533-488000aPorous anisotropic metal nanostructures through controlled transmetallation across a dialysis membrane0 aPorous anisotropic metal nanostructures through controlled trans a25650 NORTH LEWIS WAY, STEVENSON RANCH, CA 91381-1439 USAbAMER SCIENTIFIC PUBLISHERScNOV a6401-64080 v93 a

Nanostructured metals with hollow interiors are of technological importance due to their unique optoelectronic properties and enhanced surface area. We describe herein, a novel method for the synthesis of anisotropic gold and palladium nanoparticles through a simple galvanic replacement reaction across a semi-permeable dialysis membrane. The control over the reaction kinetics achieved by the presence of membrane enables one to tune the bimetal composition, particle porosity and morphology. Rapid outward diffusion of silver ions generated from the sacrificial silver nanoparticles even at room temperatures prevents the precipitation of high quantities of silver chloride, thereby circumventing the need for product purification. The porous anisotropic nanostructures have potential applications in catalysis, cell imaging and therapeutics.

10aAg/Pd Nanostructures10aAnisotropic Nanoparticles10aDialysis10aGalvanic Replacement10aPorous nanostructures10aSilver Nanotriangles10aSilver Nanowires10aTransmetallation1 aShukla, Sourabh1 aPasricha, Renu1 aSastry, Murali uhttps://library.ncl.res.in/content/porous-anisotropic-metal-nanostructures-through-controlled-transmetallation-across-001623nas a2200217 4500008004100000022001400041245012800055210006900183260007100252300001400323490000800337520078300345100002401128700002001152700001601172700001701188700001901205700001901224700003001243856013201273 2009 eng d a1932-744700aPreparation of nearly monodisperse nickel nanoparticles by a facile solution based methodology and their ordered assemblies0 aPreparation of nearly monodisperse nickel nanoparticles by a fac a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcMAR a3426-34290 v1133 a

Nickel nanoparticles have been synthesized by a simple wet chemical reduction technique in the presence of a surfactant sodium dodecyl sulfate (SDS) and a capping agent oleic acid. Varying the concentration of the surfactant and the capping agent has been found to critically govern the nature of the nanoparticles prepared. It is observed that at an optimum concentration of SDS and oleic acid, nearly monodisperse Ni nanoparticles are obtained that form highly ordered hexagonally close-packed structures on electron microscopy grids by a simple drop coating procedure. It is also shown that the presence of oleic acid is necessary for the stability of the Ni nanoparticles synthesized. Structural and magnetic characterizations of the nanoparticles are also presented.

1 aSidhaye, Deepti, S.1 aBala, Tanushree1 aSrinath, S.1 aSrikanth, H.1 aPoddar, Pankaj1 aSastry, Murali1 aPrasad, Bhagavatula L. V. uhttps://library.ncl.res.in/content/preparation-nearly-monodisperse-nickel-nanoparticles-facile-solution-based-methodology-and-001712nas a2200157 4500008004100000022001400041245013400055210006900189260011000258300001200368490000600380520100300386100002001389700001901409856012601428 2009 eng d a2040-336400aProbing differential Ag+-nucleobase interactions with isothermal titration calorimetry (ITC): towards patterned DNA metallization0 aProbing differential Agnucleobase interactions with isothermal t aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcOCT a122-1270 v13 a

DNA has been Successfully used as a scaffold for the fabrication of metallic nanowires, primarily based oil the electrostatic complexation and reduction of the metal cations on the negatively charged sugar-phosphate backbone. Here. we probe the differential binding affinities of nucleobases for silver ions using sensitive isothermal titration calorimetry (ITC) measurements of the reaction enthalpies, which go in order: C > G > A >= T. Using the disparity between the interaction of cytosine (strong binding) and thymine (weak binding) with silver ions, we have successfully generated silver nanoparticle doublets and triplets on custom-made oligonucleotides, C-30-T-40-C-30 and C-20-T-20-C-20-T-20-C-20, respectively. Thus, it new and simple method of generating metallized DNA wires is presented, based entirely on the nucleotide sequence of DNA. The concept could be extended to other cations and complex DNA sequences in order to achieve intricately patterned DNA constructs.

1 aShukla, Sourabh1 aSastry, Murali uhttps://library.ncl.res.in/content/probing-differential-ag-nucleobase-interactions-isothermal-titration-calorimetry-itc-002567nas a2200217 4500008004100000022001400041245014700055210006900202260009500271300001200366490000800378520168700386653002902073653002302102653003202125653001802157100001902175700001602194700001902210856012002229 2009 eng d a0021-979700aShape and size selective separation of gold nanoclusters by competitive complexation with octadecylamine monolayers at the air-water interface0 aShape and size selective separation of gold nanoclusters by comp a525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USAbACADEMIC PRESS INC ELSEVIER SCIENCEcMAY a380-3880 v3333 a

The paper presents a time-dependent study of shape-dependent preferential complexation of gold nanoparticles to the octadecyl amine (ODA) monolayers at the air-water interface. Room temperature reduction of chloroaurate ions using lemon grass leaf extract yields a Mixture of spherical and triangular nanoparticles, which were used for this study. These nanoparticles have a net negative charge on their surface due to the presence of biomolecules from plant extract and thus a strong attractive electrostatic interaction with the positively charged ODA monolayers drives the complexation process. The extent of preferential complexation of the gold nanoparticles to the ODA monolayers is a function of the charge on the particles and the relative mobility of the nanoclusters in the medium. The complexation process has been followed in real time by a host of techniques such as surface pressure-area (pi-A) isotherms, UV-vis-NIR spectroscopy and Brewster angle microscopy. The charge and mobility of the gold nanoparticles was confirmed by measurement of their electrophoretic mobility. Langmuir-Blodgett films of the nanogold-ODA composites have been characterized by UV-vis-NIR spectroscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy. These measurements clearly indicate that the cluster mobility and complexation increase with decreasing cluster size. In the competitive complexation process of large and small gold particles, it was observed that some bigger gold particles were also incorporated into the amine matrix even though the cluster mobility is higher for smaller gold particles. (c) 2009 Elsevier Inc. All rights reserved.

10aCompetitive complexation10agold nanoparticles10aLangmuir-Blodgett technique10aODA monolayer1 aPasricha, Renu1 aSingh, Amit1 aSastry, Murali uhttps://library.ncl.res.in/content/shape-and-size-selective-separation-gold-nanoclusters-competitive-complexation-001893nas a2200253 4500008004100000022001400041245013000055210006900185260007700254300001400331490000600345520095100351653001401302653001501316653002501331653002001356653002101376100001901397700002001416700002401436700002801460700001901488856013201507 2009 eng d a1613-681000aSynthesis of catalytically active porous platinum nanoparticles by transmetallation reaction and proposition of the mechanism0 aSynthesis of catalytically active porous platinum nanoparticles  aPO BOX 10 11 61, D-69451 WEINHEIM, GERMANYbWILEY-V C H VERLAG GMBHcJUN a1467-14730 v53 a

A facile method for the synthesis of porous platinum nanoparticles by transmetallation reactions between sacrificial nickel nanoparticles and chloroplatinic acid (H(2)PtCl(6)) in solution, as well as at the constrained environment of the air water interface, using a Langmuir-Blodgett instrumental setup is presented. To carry out the transmetallation at the air-water interface hydrophobized nickel nanoparticles are assembled as a monolayer on the sub phase containing platinum ions. The porous Pt nanoparticles obtained as a result of the reaction are found to act as extremely good catalysts for hydrogenation reaction. The products are well characterized by TEM, HRTEM, EDAX, and STEM. Attempts are made to postulate the plausible mechanism of this reaction to generate this kind of nanoparticle with controllable geometric shape and structure. This simple strategy has the potential to synthesize other nanomaterials of interest too.

10aCatalysts10aInterfaces10aNickel nanoparticles10aporous platinum10aTransmetallation1 aPasricha, Renu1 aBala, Tanushree1 aBiradar, Ankush, V.1 aUmbarkar, Shubhangi, B.1 aSastry, Murali uhttps://library.ncl.res.in/content/synthesis-catalytically-active-porous-platinum-nanoparticles-transmetallation-reaction-and-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-nanoparticles01310nas a2200169 4500008004100000022001400041245016200055210006900217260007300286300001200359490000800371520056500379100002000944700001900964700003000983856012701013 2010 eng d a0009-261400aHalide ion controlled shape dependent gold nanoparticle synthesis with tryptophan as reducing agent: enhanced fluorescent properties and white light emission0 aHalide ion controlled shape dependent gold nanoparticle synthesi aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcJAN a271-2750 v4843 a

We report the synthesis of Au nanoparticles in presence of two surfactants cetyltrimethyl ammonium chloride (CTAC) and cetyltrimethyl ammonium bromide (CTAB) by reducing Au(3+) ions with tryptophan. Interestingly, triangular shaped particles were seen to form in presence of CTAB, while spherical nanoparticles resulted with CTAC. The highlight of this result is the white light emission from the Au triangles obtained when CTAB is used. These results are supported by lifetime measurements and fluorescence. (C) 2009 Elsevier B. V. All rights reserved.

1 aKasture, Manasi1 aSastry, Murali1 aPrasad, Bhagavatula L. V. uhttps://library.ncl.res.in/content/halide-ion-controlled-shape-dependent-gold-nanoparticle-synthesis-tryptophan-reducing-001931nas a2200169 4500008004100000022001400041245008900055210006900144260011000213300001400323490000800337520123800345100001601583700002001599700001901619856012301638 2012 eng d a0003-265400aUltra-low level optical detection of mercuric ions using biogenic gold nanotriangles0 aUltralow level optical detection of mercuric ions using biogenic aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcAPR a3083-30900 v1373 a

Mercury is a serious environmental pollutant known to have detrimental health effects in all life forms. Here, we report the use of biologically synthesized aqueous gold nanotriangles for sensitive and selective optical detection of femto-molar levels of mercury ions by exploiting the high amalgamation tendency of mercury metal towards gold. Aqueous chloroaurate ions were reduced using lemongrass (Cymbopogon flexuosus) leaf extract at room temperature to form gold nanotriangles. Mercuric (Hg2+) ions were reduced in the presence of these triangles to facilitate amalgamation and the optical properties were monitored. We observe a significant change in the longitudinal plasmon absorption band of the nanotriangles even at femto-molar concentrations of mercuric ions. High-resolution transmission electron microscopy confirms changes in particle morphology at such low concentrations. This protocol shows no sensitivity to other environmentally relevant metal ions, including Pb2+, Zn2+, Cd2+, Fe2+, Ni2+, Sr2+, Ca2+, Mn2+, and Cu2+, confirming further that change in the optical properties of gold nanotriangles in the presence of reduced mercuric ions is solely due to the strong amalgamation tendency of mercury metal.

1 aSingh, Amit1 aPasrichax, Renu1 aSastry, Murali uhttps://library.ncl.res.in/content/ultra-low-level-optical-detection-mercuric-ions-using-biogenic-gold-nanotriangles-0