Preparation of amine free silica-coated Agl nanoparticles with modified stöber method

Y. Kobayashi, N. Shimizu, K. Misawa, M. Takeda, N. Ohuchi, A. Kasuya, M. Konno

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)


In recent years, the authors studied on fabrication of silica-coated Agl (Agl-SiO2) nanoparticles with a Stober method toward new X-ray contrast agents. In the Stöber method, amines are often used as catalysts for silica formation, so that it is probable that amine is left in the silica-coated particles. Since amines are harmful to the human body, amine free particles are desired for medical use. From this viewpoint, amine free Agl-SiO2 nanoparticles were prepared with a modified Stöber method using NaOH as a catalyst instead of amine in the present work. The Agl nanoparticles were prepared from AgCIO4 and Kl with the use of 3-mercaptopropyltrimethoxy- silane (MPS) as a silane coupling agent and NaOH catalyst for alkoxide hydrolysis. The silicacoating was performed at 4·5 × 10-5M MPS, 15-22·5M water, 0·0008- 0·0024M NaOH and 0·0004-0·009M tetraethylorthosilicate at an Agl concentration of 0·001M. Agl-SiO2 particles as small as ca. 30 nm could be successfully fabricated at the concentrations of 4·5 × 10-5M MPS, 20M water, 0·0011M NaOH, 0·001M Agl and 0·004M tetraethylorthosilicate.

Original languageEnglish
Pages (from-to)248-252
Number of pages5
JournalSurface Engineering
Issue number4
Publication statusPublished - 2008 Jul


  • Agl
  • Core-shell
  • Nanoparticle
  • Silica coating
  • Sol-gel
  • Stöber method

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Materials Chemistry


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