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Hydroxiapatite films on Ti and TiO2 for biological applications

Tionica Stoica 2Toma Stoica 2Adrian Slav 2Mihai Anastasescu 1Mihai Stoica 1Stefania Petrescu 3Mariuca Gartner 1

1. Instituite of Physical Chemsitry (ICF), Splaiul Independentei 202, Bucharest 060021, Romania
2. National Institute for Materials Physics, Bucharest- Magurele 010555, Romania
3. Institute for Biochemistry of Romanian Academy, Splaiul Independentei, Bucharest, Romania


Hydroxyapatite (HAp) - Ca10(PO4)6(OH)2 - is one of the most investigated materials for bone implants due to its suitable chemical composition and morphology which is very similar with mineralized bones of human tissues. Recently, it was reported that the biocompatible hydroxyapatite granules were successfully employed to fill the bone defects and that these defects were faster restored with HA granules of smaller diameters, in the micrometer scale.

Under these circumstances, the aim of this work was to find the optimal conditions regarding both deposition and annealing conditions for obtaining HAp coatings of tailored thickness, roughness, porosity and bioactivity. By using the sol–gel method, amorphous as well as crystalline coatings can be obtained with a very good control of the composition and stoichiometry. Spectroscopic ellipsometry in combination with Atomic Force Microscopy was used to characterize the structural and morphological properties of the HAp films deposited on Titanium and Titania buffer layers. Thus, it was found that the HAp films deposited directly on Ti are thicker, more porous, and exhibit surface deposits as well as pits. The films obtained by using a buffer layer of TiO2 between the substrates and HAp, are thinner, less porous, with a uniform granular structure which was consistently characterized. For all samples, a low value of the annealing temperature determines the lowering of the surface roughness and porosity.

The bioactivity tests performed with osteoblast/osteosarcoma cells evidenced a good correlation between the densities of the primar cells and the composition of the layers. The highest cell density was observed on the HA samples with two layers. The studied HAp films exhibit a good mechanical stability leading to the cell adherence and normal proliferation on the tested surfaces. No cell morphological changes occur.

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Presentation: Poster at E-MRS Fall Meeting 2008, Workshop, by Mihai Anastasescu
See On-line Journal of E-MRS Fall Meeting 2008

Submitted: 2008-05-19 22:46
Revised:   2009-06-07 00:48