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Synthèse et caractérisations de nanotubes de TiO2 pour applications biomédicales : propriétés électrochimiques et bioactivité

Abstract : Titanium (Ti) is a biocompatible material widely used in the biomedical field, especially for orthopedic implants (for instance hip or knee replacement). It is particularly corrosion resistant and shows remarkable osseointegration properties. However, plane Ti surfaces are not bioactive enough to be implanted; they need to be improved by surface treatments. Surface modification of Ti by anodization enables to synthesize self-organized and vertically aligned TiO2 nanotubes (NTs). This cheap, fast and easily implementable technique also permits a fine tuning of NTs morphology (diameter, length, wall look, etc.). Moreover, since as-anodized NTs are amorphous, crystalline structure may be adjusted by heat treatment, producing anatase structure (450°C) or a mixed structure of anatase and rutile (550°C).Therefore, surfaces of different morphologies and crystalline structures have been synthesized in order to evaluate the influence of these characteristics on corrosion resistance in physiological medium and on bioactivity (hydroxyapatite formation and cell response).We demonstrated that crystallized NTs are more corrosion resistant and more bioactive than amorphous ones or even than flat Ti surfaces. More precisely, considering electrochemical, thermal, mechanical, chemical and bioactive aspects, it seems that mixed NTs of about 720 nm in length and 90 nm in diameter constitute an optimal surface for the present applications.Additionally, in the frame of electrochemical investigations, we focused on modeling experimental results from Electrochemical Impedance Spectroscopy (EIS) measurements. The impedance response of TiO2 NTs in physiological conditions can correspond to porous electrode model as developed by De Levie. However, for non-ideal electrodes, this theory can be generalized and modeled by transmission lines. Thus, the transmission line model developed in this study fits very well with experimental measurements. It suggests that TiO2 NTs are almost non-reactive, justifying their applications in biomedical fields.
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Submitted on : Monday, June 11, 2018 - 3:22:07 PM
Last modification on : Wednesday, October 14, 2020 - 4:17:53 AM


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  • HAL Id : tel-01812557, version 1



Fanny Hilario. Synthèse et caractérisations de nanotubes de TiO2 pour applications biomédicales : propriétés électrochimiques et bioactivité. Génie chimique. Université Grenoble Alpes, 2017. Français. ⟨NNT : 2017GREAI121⟩. ⟨tel-01812557⟩



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