Formation of oriented hydroxyapatite crystals in a hydrogel

Taishi Yokoi, Ill Yong Kim, Masakazu Kawashita, Chikara Ohtsuki

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Calcium phosphate-polymer composites have been produced for bone-repairing. We have focused development of composites by a crystal growth technique in a hydrogel matrix, that is regarded as gel-mediated processing. Under the gel-mediated condition, reaction temperature is one of the major parameter to determine microstructure of the precipitated crystals. In the present study, we investigated effects of the reaction temperature on formation of calcium phosphates through gel-mediated processing where double diffusion technique was applied. Crystalline phases of calcium phosphate formed in the hydrogel were varied from octacalcium phosphate (OCP) to hydroxyapatite (HAp) with increasing the reaction temperature. OCP crystals formed at 4 and 40 °C had granular or spherical shape, while HAp crystals formed at 80 °C had rod shape. The HAp crystals were composed of a large number of fibrous crystals. The rod-shaped HAp crystals were oriented in the direction of ion diffusion. Formation of oriented HAp crystals was generated by increase in diffusion rate of ions in the hydrogel matrix after increasing reaction temperature in gel-mediated processing.

Original languageEnglish
Title of host publicationBioceramics 24
PublisherTrans Tech Publications Ltd
Number of pages5
ISBN (Print)9783037855171
Publication statusPublished - 2013
Event24th Symposium and Annual Meeting of International Society for Ceramics in Medicine, ISCM 2012 - Fukuoka, Japan
Duration: 2012 Oct 212012 Oct 24

Publication series

NameKey Engineering Materials
ISSN (Print)1013-9826
ISSN (Electronic)1662-9795


Other24th Symposium and Annual Meeting of International Society for Ceramics in Medicine, ISCM 2012


  • Crystal growth
  • Hydrogel
  • Hydroxyapatite
  • Octacalcium phosphate
  • Orientation

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering


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