Control of shell thickness in silica-coating of Au nanoparticles and their X-ray imaging properties

Yoshio Kobayashi, Hiromitsu Inose, Tomohiko Nakagawa, Kohsuke Gonda, Motohiro Takeda, Noriaki Ohuchi, Atsuo Kasuya

Research output: Contribution to journalArticlepeer-review

65 Citations (Scopus)


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/SiO2) particles. The Au nanoparticles with a size of 16.9±1.2nm 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, H2O, NaOH, and APMS, the Au/SiO2 particles with silica shell thickness of 6.0-61.0nm were produced with varying TEOS concentration. Absorption peak wavelength of surface plasmon resonance of the Au/SiO2 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 0.19M 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 0.129M was achieved 1329.7±52.7HU.

Original languageEnglish
Pages (from-to)329-333
Number of pages5
JournalJournal of Colloid and Interface Science
Issue number2
Publication statusPublished - 2011 Jun 15


  • Core-shell
  • Gold
  • Nanoparticle
  • Silica
  • Surface plasmon resonance
  • X-ray imaging


Dive into the research topics of 'Control of shell thickness in silica-coating of Au nanoparticles and their X-ray imaging properties'. Together they form a unique fingerprint.

Cite this