Surface structural changes of sintered hydroxyapatite in terms of surface charge

T. Himeno, H. M. Kim, H. Kaneko, M. Kawashita, T. Kokubo, T. Nakamura

Research output: Contribution to journalConference articlepeer-review

6 Citations (Scopus)

Abstract

Variations of surface structure and charge of sintered hydroxyapatite (HA) in simulated body fluid (SBF) were investigated during forming bonelike apatite on its surface using transmission electron microscopy accompanied with energy-dispersive X-ray spectrometry (TEM-EDX) and laser electrophoresis spectroscopy. TEM-EDX indicated that the HA appreciably increased its Ca/P ratio up to 1.84 during early soaking period in SBF to form a Ca-rich calcium phosphate, and then decreased the Ca/P ratio to 1.46 to form an amorphous calcium phosphate. Thereafter the amorphous calcium phosphate gradually increased its Ca/P ratio up to 1.65 to convert into crystalline apatite. Electrophoresis showed that surface charge of HA was highly negative immediately after soaking in SBF, increased up to positive value during subsequent period, and then again decreased to converge a constant negative value. Therefore formation of Ca-rich calcium phosphate at an initial stage is attributed to combination of positively calcium ion in SBF on the negatively charged HA, and the subsequent formation of amorphous calcium phosphate with low Ca/P ratio is attributed to combination of negatively charged phosphate ion on the positively charged Ca-rich calcium phosphate. Since this phase is metastable, it eventually transformed into crystalline apatite.

Original languageEnglish
Pages (from-to)457-460
Number of pages4
JournalKey Engineering Materials
Volume240-242
Publication statusPublished - 2003 Jan 1
EventProceedings of the 15th International Symposium on Ceramics in Medicine; The Annual Meeting of the International Society for Ceramics in Medicine - Sydney, NSW, Australia
Duration: 2002 Dec 42002 Dec 8

Keywords

  • Apatite
  • Energy dispersive X-ray spectrometry (EDX)
  • Hydroxyapatite
  • Simulated body fluid (SBF)
  • Transmission electron microscopy (TEM)
  • Zeta-potential

ASJC Scopus subject areas

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

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