Experimental evidence and structural modeling of nonstoichiometric (010) surfaces coexisting in hydroxyapatite nano-crystals

C. A. Ospina, J. Terra, A. J. Ramirez, M. Farina, Donald E Ellis, A. M. Rossi*

*Corresponding author for this work

Research output: Contribution to journalArticle

24 Scopus citations

Abstract

High-resolution transmission electron microscopy (HRTEM) and ab initio quantum-mechanical calculations of electronic structure were combined to investigate the structure of the hydroxyapatite (HA) (0. 1. 0) surface, which plays an important role in HA interactions with biological media. HA was synthesized by in vitro precipitation at 37 °C. HRTEM images revealed thin elongated rod nanoparticles with preferential growth along the [0. 0. 1] direction and terminations parallel to the (0. 1. 0) plane. The focal series reconstruction (FSR) technique was applied to develop an atomic-scale structural model of the high-resolution images. The HRTEM simulations identified the coexistence of two structurally distinct terminations for (0. 1. 0) surfaces: a rather flat Ca(II)-terminated surface and a zig-zag structure with open OH channels. Density functional theory (DFT) was applied in a periodic slab plane-wave pseudopotential approach to refine details of atomic coordination and bond lengths of Ca(I) and Ca(II) sites in hydrated HA (0. 1. 0) surfaces, starting from the HRTEM model.

Original languageEnglish (US)
Pages (from-to)15-22
Number of pages8
JournalColloids and Surfaces B: Biointerfaces
Volume89
Issue number1
DOIs
StatePublished - Jan 1 2012

Keywords

  • HRTEM
  • Hydroxyapatite
  • Modeling
  • Surface analysis

ASJC Scopus subject areas

  • Biotechnology
  • Surfaces and Interfaces
  • Physical and Theoretical Chemistry
  • Colloid and Surface Chemistry

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