title: Control of shell thickness in silica-coating of Au nanoparticles and their X-ray imaging properties.
abstract: This paper describes a performance of precise control of shell thickness in silica-coating of Au nanoparticles based on a sol-gel process, and an investigation into X-ray imaging properties for the silica-coated Au (Au/SiO(2)) particles. The Au nanoparticles with a size of 16.9±1.2 nm prepared through a conventional citrate reduction method were used as core particles. The Au nanoparticles were silica-coated with a sol-gel reaction using tetraethylorthosilicate (TEOS) as a silica source, sodium hydroxide (NaOH) as a catalyst, and (3-aminopropyl) trimethoxysilane (APMS) as a silane coupling agent. An increase in TEOS concentration resulted in an increase in shell thickness. Under certain concentrations of Au, H(2)O, NaOH, and APMS, the Au/SiO(2) particles with silica shell thickness of 6.0-61.0 nm were produced with varying TEOS concentration. Absorption peak wavelength of surface plasmon resonance of the Au/SiO(2) colloid solution depended on silica shell thickness, which agreed approximately with the predictions by Mie theory. The as-prepared colloid solution could be concentrated up to an Au concentration of 0.19 M with salting-out and centrifugation. The concentrated colloid solution showed an X-ray image with high contrast, and a computed tomography value for the colloid solution with an Au concentration of 0.129 M was achieved 1329.7±52.7 HU.
authors: Department of Biomolecular Functional Engineering, College of Engineering, Ibaraki University, Ibaraki 316-8511, Japan. ykoba@mx.ibaraki.ac.jp
authors: Yoshio
authors: Y
authors: Kobayashi
authors: Hiromitsu
authors: H
authors: Inose
authors: Tomohiko
authors: T
authors: Nakagawa
authors: Kohsuke
authors: K
authors: Gonda
authors: Motohiro
authors: M
authors: Takeda
authors: Noriaki
authors: N
authors: Ohuchi
authors: Atsuo
authors: A
authors: Kasuya
mesh_terms: D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D003102:Colloids / Q000737:chemistry; D006046:Gold; D053768:Metal Nanoparticles / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry*; D014057:Tomography, X-Ray Computed
chemical_list: D020099:Coated Materials, Biocompatible; D003102:Colloids; D006046:Gold; D012822:Silicon Dioxide