In vitro and in vivo biocompatibility and corrosion behaviour of a bioabsorbable magnesium alloy coated with octacalcium phosphate and hydroxyapatite

Sachiko Hiromoto, Motoki Inoue, Tetsushi Taguchi, Misao Yamane, Naofumi Ohtsu

Research output: Contribution to journalArticle

96 Citations (Scopus)

Abstract

Octacalcium phosphate (OCP) and hydroxyapatite (HAp) coatings were formed on Mg-3 mass% Al-1 mass% Zn (AZ31) magnesium alloy by a single-step chemical solution deposition method. Chemically polished AZ31 (Cpol-AZ31) and HAp- and OCP-coated AZ31 (HAp- and OCP-AZ31) were immersed in a medium for 52 weeks or implanted in transgenic mice for 16 weeks to examine the long-term corrosion behaviour and in situ inflammation behaviour. In the medium, Mg-ion release was restricted for the initial several days and the corrosion rate thereafter was suppressed by approximately one-half with the HAp and OCP coatings. HAp-AZ31 showed a ∼20% lower corrosion rate than OCP-AZ31. Tissues of the transgenic mouse emit fluorescence in proportion to the degree of inflammation in situ. The luminescence intensity level was too low to be a problem regardless of the coatings. A thinner fibrous tissue layer was formed around OCP- and HAp-AZ31 than around Cpol-AZ31, indicating that the HAp and OCP coatings suppressed corrosion and foreign-body reaction in vivo. Visible pits were formed in filiform and round shapes in vitro and in vivo, respectively. Corrosion was observed underneath the coatings, and almost uniform corrosion took place in vitro, while local corrosion was predominant in vivo. These differences in corrosion morphology are attributed to the adhesion of tissues and the lower diffusivity on the surface in vivo than that in vitro. Dissolution behaviour of OCP crystals in vivo was different from that in vitro. It was demonstrated that the HAp and OCP coatings developed have great potential for a biocompatible and corrosion protection coating.

Original languageEnglish
Pages (from-to)520-530
Number of pages11
JournalActa Biomaterialia
Volume11
Issue number1
DOIs
Publication statusPublished - 2015 Jan 1
Externally publishedYes

Keywords

  • Biocompatibility
  • Calcium phosphate coatings
  • Corrosion
  • In vivo
  • Magnesium

ASJC Scopus subject areas

  • Biotechnology
  • Biomaterials
  • Biochemistry
  • Biomedical Engineering
  • Molecular Biology

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