Au Nanoparticle - C O M M U N I C AT I O N Materials Chemistry Journal of Novel one-step synthesis of amine-stabilized

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COMMUNICATION Journal of Materials Chemistry Novel one-step synthesis of amine-stabilized aqueous colloidal gold nanoparticles { M. Aslam, a Lei Fu, a Ming Su, a K. Vijayamohanan b and Vinayak P. Dravid* a a Department of Materials Science and Engineering, Institute for Nanotechnology, Northwestern University, Evanston, Illinois, 60208, USA. E-mail: [email protected] b Physical and Materials Chemistry Division, National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008, India Received 24th February 2004, Accepted 4th May 2004 First published as an Advance Article on the web 19th May 2004 We demonstrate a simple one-step process for the synthesis of water-dispersed spherical gold nanoparticles using the multifunctional molecule oleyl amine (OLA) that electrostatically complexes with aqueous chloroaurate ions, reduces them, and subsequently caps the nano- particles thus formed. The gold particles thus formed were of the fcc phase and were fairly monodisperse with particular concentrations of capping molecules. After Brust et al. 1 demonstrated alkanethiol capped Au nano- particles formation in a biphasic mixture, there has been an enormous effort to functionalize these particles with terminally functionalized alkanethiols or arenethiolates. 2 However, these gold nanoparticles are prepared in organic solvents and they were redispersible in nonpolar and weakly polar organic solvents. 3 Gold particles are also prepared by chemical reduc- tion of a chloride precursor under aqueous conditions: for example, the well-known Turkevich method 4 involves reduc- tion of HAuCl 4 by sodium citrate in water while Schmid has demonstrated that the reduction of AuCl(PR 3 )byB 2 H 6 leads to Au 55 nanoclusters. 5 However, a study of the recent literature reveals the need for new preparative methods leading to monodisperse particles of adjustable size and shape. 6 Develop- ment of synthesis protocols for realizing monolayer-protected water-dispersible gold nanoparticles, on the other hand, has received considerably less attention and would have immediate applications in catalysis, sensors, molecular markers, and in particular, biological applications such as biolabeling and drug delivery. Recognizing that the solubility of gold, and in some instances silver, monolayer-protected nanoclusters (MPCs) in water/strongly polar organic solvents would be dominated by the terminal functionality of the capping monolayer, 7 a number of different thiol-coordinated functional groups such as tio- pronin, 8 glutathione, 9 succinic acid, 10 sulfonic acid 11 and ammonium ions 12 have been shown to result in MPCs that are readily dispersible in water. Recently there have been several reports where tertiary amine/amine adducts were used to form Ag nanoparticles using organometallic Ag complexes in organic medium.
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This note was uploaded on 01/12/2011 for the course ME 305 taught by Professor Wright,j during the Spring '10 term at Birla Institute of Technology & Science, Pilani - Hyderabad.

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Au Nanoparticle - C O M M U N I C AT I O N Materials Chemistry Journal of Novel one-step synthesis of amine-stabilized

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