Concentrated colloids of silica-encapsulated gold nanoparticles: Colloidal stability, cytotoxicity, and X-ray absorption

Yeon Su Park, Atsuo Kasuya, Andriy Dmytruk, Noda Yasuto, Motohiro Takeda, Noriaki Ohuchi, Yoshinori Sato, Kazuyuki Tohji, Motohiro Uo, Fumio Watari

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)


As an effort to develop a new, effective, nontoxic X-ray contrast agent, the concentrated colloids of silica-encapsulated gold nanoparticles (Au@SiO 2 NPs) were fabricated and their colloidal stability, cytotoxicity, and X-ray absorption were investigated. The concentrated colloidal NPs were manufactured by forming a 4 nm-thick silica shell on the surface of each Au NP with 15 nm diameter, followed by enrichment to [Au] = 100 mM. They were very stable in water: the NPs were well separated each other without forming agglomerates and their optical property was very similar to that before enrichment. The colloidal stability of the NPs in biological environment was strongly dependent on their previous morphology in water. The NPs with minor shell damage were stable in phosphate buffered saline (PBS) solution: both in water and in PBS solution, they showed very similar morphology and optical property. However, the NPs with profound shell damage formed big agglomerates in PBS solution, resulting in the red-shift and broadening of the Au surface plasmon resonance peak. Cell viability and proliferation assessments revealed the biocompatibility of the Au@SiO 2 NPs: no apparent cytotoxicity was observed even at 100 ppm NPs. The concentrated colloidal NPs showed very strong X-ray absorption. Their relative X-ray transmittance to water was comparable to that of a commercial agent. Considering these, the concentrated colloids of the Au@SiO 2 NPs are suitable for an X-ray contrast agent.

Original languageEnglish
Pages (from-to)2690-2695
Number of pages6
JournalJournal of Nanoscience and Nanotechnology
Issue number8
Publication statusPublished - 2007 Aug


  • Colloidal stability
  • Cytotoxicity
  • Gold
  • Silica
  • X-ray absorption

ASJC Scopus subject areas

  • Bioengineering
  • Chemistry(all)
  • Biomedical Engineering
  • Materials Science(all)
  • Condensed Matter Physics


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