Titanium Modified with Layer-by-Layer Sol-Gel Tantalum Oxide and an Organodiphosphonic Acid: A Coating for Hydoxyapatite Growth

Titanium and its alloys are widely used in surgical implants due to their appropriate properties like corrosion resistance, biocompatibility and load-bearing. Unfortunately the use of metals for orthopaedic and dental implants is confronted to the possibility of loosening over a long period of time. Surface modification is a good way to counter this problem. A thin tantalum oxide layer obtained by layer-by-layer (LBL) sol-gel deposition has the aim to improve biocorrosion resistance in the body fluid, biocompatibility and radio-opacity. This elaboration step is followed by a surface modification with organodiphosphonic acids, which have the properties to chemically bond to the oxide surface, but also to improve hydroxyapatite growth. The different steps of the coating formation are characterized by surfaces techniques like contact angle, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM).