Mechanical and in vitro testing of aerosol-gel deposited titania coatings for biocompatible applications

The biocompatible properties of sol-gel titania have increased the interest in the mechanical properties of this material in the form of functional coatings for prosthetic applications. In the present work, titania coatings with thicknesses of 1 mum have been prepared using the aerosol-gel process. The main objective has been to evaluate the mechanical properties of the coatings and to prove their in-vitro biocompatibility. For this purpose, the hardness and Young's modulus of the coatings were measured by nanoindentation with loads in the 6-30mN range. A continuous increase of these magnitudes was observed for the coatings treated at increasing sintering temperatures (150 800 degreesC). The hardness and the Young's modulus ranged between 15.8-19.5GPa and 142-186GPa, respectively. This behaviour has been confirmed by measurements of the plastic energy of deformation in 10 mN full loading-unloading tests and by determination of the mean indentation creep under 30 mN loads. The films were additionally characterised by XRD, FTIR and ellipsometry to study the chemical and structural changes produced by sintering. Biocompatibility tests are very conclusive. Cells seeded on aerosol-gel titania coatings grow while adhered onto the surface. These coatings are thus of potential interest for the enhancement of the properties of prosthetic TiAlV alloys. (C) 2001 Elsevier Science Ltd. All rights reserved.