Preparation of high-concentration colloidal solution of silica-coated gold nanoparticles and their application to X-ray imaging

Yoshio Kobayashi, Kyosuke Shibuya, Masayuki Tokunaga, Yohsuke Kubota, Takahiro Oikawa, Kohsuke Gonda

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)


Abstract: This study proposes a method for preparing high-concentration silica-coated Au (Au/SiO2) nanoparticles in colloidal solution from 1.5 × 10−3 M hydrogen tetrachloroaurate (III) trihydrate as the Au source and 1.0 × 10−2 M sodium citrate as the reducing reagent. The colloidal solution is applied to X-ray computed tomography (CT) imaging of mouse tissue. The Au nanoparticles in the colloidal solution had a diameter of 18.9 nm, and the Au concentration reached 1.5 × 10−3 M. The Au nanoparticles were silica-coated by modifying their surfaces with (3-aminopropyl)trimethoxysilane (APMS), then depositing silica nuclei generated by a sol–gel reaction of tetraethyl orthosilicate (TEOS) in water/ethanol initiated with sodium hydroxide (NaOH) on the surface modified with APMS. A colloidal solution of Au/SiO2 core–shell particles (silica shell thickness = 19.7 nm) was formed in a final as-prepared solution of 2.7 × 10−4 M Au, 2.0 × 10−5 M APMS, 24 M H2O, 1.9 × 10−3 M NaOH, and 4.1 × 10−3 M TEOS. The Au in the as-prepared colloidal solution was further concentrated to 0.27 M by salting-out and centrifugation. The CT value of the concentrated Au/SiO2 colloidal solution was 2.52 × 103 Hounsfield units, double that of a commercial X-ray contrast agent with the same I concentration as the Au concentration. When injected into mouse tissue, the Au/SiO2 colloidal solution demonstrated good imaging capability. Graphical Abstract: [Figure not available: see fulltext.]

Original languageEnglish
Pages (from-to)82-90
Number of pages9
JournalJournal of Sol-Gel Science and Technology
Issue number1
Publication statusPublished - 2016 Apr 1


  • Au
  • Core–shell
  • Nanoparticle
  • Silica
  • X-ray contrast agent

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Chemistry(all)
  • Biomaterials
  • Condensed Matter Physics
  • Materials Chemistry


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