Increased Osteoblast Adhesion on Nanograined Hydroxyapatite and Tricalcium Phosphate Calcium Titanate Composites
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0950-D15-20
Increased Osteoblast Adhesion on Nanograined Hydroxyapatite and Tricalcium Phosphate Calcium Titanate Composites Huinan Liu1, Celaletdin Ergun2, John W. Halloran3, and Thomas J. Webster1 1 Division of Engineering, Brown University, 182 Hope Street, Providence, RI, 02912 2 Mechanical Engineering Department, Istanbul Technical University, Istanbul, 34437, Turkey 3 Materials Science and Engineering, University of Michigan, Ann Arbor, MI, 48109 ABSTRACT Depending on the coating method utilized and subsequent heat treatments (such as through the use of plasma-spray deposition), inter-diffusion of atomic species across titanium (Ti) and hydroxyapatite (HA) coatings may result. These events may lead to structural and compositional changes that consequently cause unexpected HA phase transformations which may clearly influence the performance of an orthopedic implant. Thus, the objective of the present in vitro study was to compare the cytocompatibility properties of chemistries that may form at the Ti:HA interface, specifically HA, tricalcium phosphate (TCP), Ti doped HA, and those containing calcium titanate (CaTiO3). In doing so, results of this in vitro study showed that osteoblast adhesion increased with greater CaTiO3 substitutions in either HA or TCP. Specifically, osteoblast adhesion on HA and TCP composites with CaTiO3 was almost 4.5 times higher than over pure HA. Material characterization studies revealed that enhanced osteoblast adhesion on these compacts may be due to increasing shrinkage in the unit lattice parameters and consequent decrease in grain size. Although all CaTiO3 composites exhibited excellent osteoblast adhesion results, Ca9HPO4(PO4)5OH phase formation into TCP/CaTiO3 increased osteoblast adhesion the most; due to these reasons, these materials should be further studied for orthopedic applications. INTRODUCTION Previous research on titanium (Ti) and HA coatings revealed significant elemental Ti diffusion into the HA structure [1,2]; specifically, Ti doped HA and calcium titanate (CaTiO3) may be formed as a result of this atomic diffusion at the Ti:HA coating interface [3, 4]. Importantly, it has been demonstrated that CaTiO3 increases osteoblast adhesion compared to both pure HA and Ti and, thus, could possibly be beneficial if formed during the coating process. Moreover, significant apatite growth on CaTiO3 in simulated body fluid (SBF) has been observed, thus, providing promise for the formation of bone-like structures on CaTiO3 [5]. Therefore, CaTiO3 itself may be regarded as a desirable interfacial bioceramic for orthopedic implant applications. For these reasons, to improve the mechanical and biological properties of orthopedic implants, it is possible to design single-phase materials or composites-based materials with CaTiO3; this remains largely uninvestigated. Thus, the objective of the present in vitro study was to compare the cytocompatibility properties of chemistries that may form at the Ti:HA interface, specifically HA, tricalcium phosphate (TCP), Ti doped HA, and composi
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