02138nas a2200229 4500008004100000022001400041245015600055210006900211260009200280300001400372490000600386520124100392653001701633653001801650653001901668653002101687100002501708700001401733700001701747700001501764856012901779 2005 eng d a1533-488000aBiosynthesis of gold and silver nanoparticles using emblica officinalis fruit extract, their phase transfer and transmetallation in an organic solution0 aBiosynthesis of gold and silver nanoparticles using emblica offi a26650 THE OLD RD, STE 208, VALENCIA, CA 91381-0751 USAbAMER SCIENTIFIC PUBLISHERScOCT a1665-16710 v53 a

The design, synthesis and characterization of biologically synthesized nanomaterials have become an area of significant interest. In this paper, we report the extracellular synthesis of gold and silver nanoparticles using Emblica Officinalis (amla, Indian Gooseberry) fruit extract as the reducing agent to synthesize Ag and Au nanoparticles, their subsequent phase transfer to an organic solution and the transmetallation reaction of hydrophobized silver nanoparticles with hydrophobized chloroaurate ions. On treating aqueous silver sulfate and chloroauric acid solutions with Emblica Officinalis fruit extract, rapid reduction of the silver and chloroaurate ions is observed leading to the formation of highly stable silver and gold nanoparticles in solution. Transmission Electron Microscopy analysis of the silver and gold nanoparticles indicated that they ranged in size from 10 to 20 nm and 15 to 25 nm respectively. Ag and Au nanoparticles thus synthesized were then phase transferred into an organic solution using a cationic surfactant octadecylamine. Transmetallation reaction between hydrophobized silver nanoparticles and hydrophobized chloroaurate ions in chloroform resulted in the formation of gold nanoparticles.

10aBiosynthesis10aNanomaterials10aPhase transfer10aTransmetallation1 aAnkamwar, Balaprasad1 aDamle, C.1 aAhmad, Absar1 aSastry, M. uhttp://library.ncl.res.in/content/biosynthesis-gold-and-silver-nanoparticles-using-emblica-officinalis-fruit-extract-their-002945nas a2200241 4500008004100000022001400041245013500055210006900190260009500259300001200354490000800366520202500374653001302399653000902412653001902421653004502440653001102485100002002496700001402516700003002530700001502560856012802575 2005 eng d a0021-979700aPhase transfer of oleic acid capped NicoreAgshell nanoparticles assisted by the flexibility of oleic acid on the surface of silver0 aPhase transfer of oleic acid capped NicoreAgshell nanoparticles  a525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USAbACADEMIC PRESS INC ELSEVIER SCIENCEcMAR a422-4310 v2833 a

The phase transfer protocols in vogue for the oleic acid capped silver nanoparticles, viz., salt-induced precipitation and redispersion or phosphoric acid-induced method, are examined and compared thoroughly. A comprehensive evaluation with respect to the mechanistic aspects involved is made and the merits and demerits of the different procedures are delineated. It is found that the salt-induced precipitation and redispersion is more versatile in that the precipitate can actually be redispersed in both aqueous and organic media. However, in terms of mechanism both the routes seem to be very similar wherein the orientational change of oleic acid on the silver surface in the two different environments-organic and aqueous-plays a crucial role in the adaptability of the system to the different environments. Subsequently, this change of orientation of oleic acid on silver surface in aqueous and organic media has been utilized to phase transfer Ni-based nanoparticulate systems. The nascent oleic acid-capped Ni nanoparticles, which were synthesized by a foam-based protocol, were dispersible in water but not in nonpolar organic media such as cyclohexane or toluene. Then, just by coating a thin shell of silver on them we could achieve complete phase transfer of the NicoreAgshell from aqueous to organic media following similar procedures used for oleic acid-capped silver nanoparticles. Here, the phase transfer seems to be facilitated by the orientational flexibility of oleic acid on the silver surface as opposed to other metal surfaces as evidenced from the infrared and thermogravimetric analyses of oleic acid-capped Ni and NicoreAgshell nanoparticles. This orientation-assisted phase transfer method could be generalized and can be adapted to other systems where, if the nascent nanoparticles cannot be phase transferred as is, they can be coated by a silver shell and oleic acid making them suitable for dispersion in both aqueous and organic media. (C) 2004 Elsevier Inc. All rights reserved.

10a(1) HNMR10aFTIR10aPhase transfer10atransmetalation core-shell nanoparticles10aUV-Vis1 aBala, Tanushree1 aSwami, A.1 aPrasad, Bhagavatula L. V.1 aSastry, M. uhttp://library.ncl.res.in/content/phase-transfer-oleic-acid-capped-nicoreagshell-nanoparticles-assisted-flexibility-oleic-001951nas a2200241 4500008004100000022001400041245011200055210006900167260009500236300001400331490000600345520104000351653001301391653003201404653002101436653001901457100002001476700002301496700001801519700001901537700003001556856012301586 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. uhttp://library.ncl.res.in/content/assembly-phase-transferred-nickel-nanoparticles-air-water-interface-using-langmuir-001778nas a2200253 4500008004100000022001400041245013200055210006900187260007300256300001000329490000800339520080200347653002301149653002901172653003301201653002101234653001901255653002701274100002301301700002801324700001501352700003001367856012701397 2009 eng d a0927-775700aOptical limiting properties of hydrophobic poly(etherimide) membranes embedded with isolated and aggregated gold nanostructures0 aOptical limiting properties of hydrophobic polyetherimide membra aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcDEC a79-830 v3523 a

A simple method to incorporate spherical or aggregated nanostructures of gold into hydrophobic poly(etherimide) membranes is demonstrated and their comparative nonlinear optical properties are investigated. When excited at 532 nm using laser pulses of 7 ns duration, a reduced transmission behaviour in both the cases, viz., polymers embedded with isolated nanoparticles and their aggregates is observed. This fits to a three-photon type nonlinear absorption process and is attributed to excited state absorption occurring in the nanostructures. Interestingly, the nonlinearity is more prominent in the aggregated nanostructures compared to the spherical nanostructures. These materials are potential candidates for optical limiting applications. (C) 2009 Elsevier B.V. All rights reserved.

10agold nanoparticles10aNanoparticle aggregation10aNonlinear optical properties10aOptical limiting10aPhase transfer10aPolymer nanocomposites1 aD'Britto, Virginia1 aSandeep, C., S. Suchand1 aPhilip, R.1 aPrasad, Bhagavatula L. V. uhttp://library.ncl.res.in/content/optical-limiting-properties-hydrophobic-polyetherimide-membranes-embedded-isolated-and-0