Preparation of antibacterial silver-doped silica glass microspheres

Masakazu Kawashita, Shogo Toda, Hyun Min Kim, Tadashi Kokubo, Noriaki Masuda

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123 Citations (Scopus)


Various types of inorganic substances doped with silver ions have been developed as antibacterial materials, and some have already been commercialized. Colorless and chemically durable materials that slowly release silver ions are, however, still need to be developed. The present authors have previously shown that when a silica glass doped with silver and aluminium ions is prepared using the sol-gel method, the resultant product is colorless, chemically durable, and slowly releases silver ions into water over a long period. The doped silica glass takes a form of microspheres <1 μm in diameter, it is easily mixed with organic polymers, and the mixture can be formed into a thin film or fine fibers, etc. We report on the preparation of silver doped silica glass microspheres having a diameter =1 μm, using the sol-gel method. Initially, tetraethoxysilane was partially prehydrolyzed by water in ethanol, and then aluminium triisopropoxide was added to the solution to form Si-O-Al bonds. Finally, an ammonia solution containing silver nitrate was added to form silica microspheres doped with silver ion together with aluminium ions. The results show monodispersed microspheres 0.4-0.6 μm in diameter were obtained with nominal compositions of Si/Al/Ag = 1/0.01-0.03/0.003-0.03, with a molar ratio of Al/Ag = 1-3.3. The microspheres were colorless, showed a high chemical durability, and slowly released silver ions into water at 37°C. Microspheres with the composition Si/Al/Ag = 1/0.01/0.01 showed excellent antibacterial activity against Escherichia coli. The minimum inhibitory concentration (MIC) of the microspheres was 400, which is less than the MIC value (800) of commercial antibacterial materials.

Original languageEnglish
Pages (from-to)266-274
Number of pages9
JournalJournal of Biomedical Materials Research - Part A
Issue number2
Publication statusPublished - 2003 Aug 1


  • Aluminium
  • Antibacterial property
  • Silica glass microspheres
  • Silver
  • Sol-gel method

ASJC Scopus subject areas

  • Ceramics and Composites
  • Biomaterials
  • Biomedical Engineering
  • Metals and Alloys


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