01831nas 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<p>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.</p>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-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<p>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.</p>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-0