Osteoblast responses to different oxide coatings produced by the sol–gel process on titanium substrates

• Published in: Acta biomaterialia 2008-09, Vol.4 (5), p.1506-1517
• Main Authors: Ochsenbein, Anne, Chai, Feng, Winter, Stefan, Traisnel, Michel, Breme, Jürgen, Hildebrand, Hartmut F.
• Format: Article
• Language: English
• Subjects: 3T3 Cells; Animals; Cell Adhesion - drug effects; Cells, Cultured; Coated Materials, Biocompatible - chemistry; Coated Materials, Biocompatible - pharmacology; Materials Testing; Mice; Niobium oxide; Osseointegration - physiology; Osteoblast; Osteoblasts - cytology; Osteoblasts - drug effects; Osteoblasts - physiology; Oxides - chemistry; Oxides - pharmacology; Phase Transition; Sol–gel coating; Surface Properties; Titanium; Titanium - chemistry; Titanium oxide
• ISSN: 1742-7061; 1878-7568
• DOI: 10.1016/j.actbio.2008.03.012

In order to improve the osseointegration of endosseous implants made from titanium, the structure and composition of the surface were modified. Mirror-polished commercially pure (cp) titanium substrates were coated by the sol–gel process with different oxides: TiO 2, SiO 2, Nb 2O 5 and SiO 2–TiO 2. The coatings were physically and biologically characterized. Infrared spectroscopy confirmed the absence of organic residues. Ellipsometry determined the thickness of layers to be approximately 100 nm. High resolution scanning electron microscopy (SEM) and atomice force microscopy revealed a nanoporous structure in the TiO 2 and Nb 2O 5 layers, whereas the SiO 2 and SiO 2–TiO 2 layers appeared almost smooth. The R a values, as determined by white-light interferometry, ranged from 20 to 50 nm. The surface energy determined by the sessile-drop contact angle method revealed the highest polar component for SiO 2 (30.7 mJ m −2) and the lowest for cp-Ti and 316L stainless steel (6.7 mJ m −2). Cytocompatibility of the oxide layers was investigated with MC3T3-E1 osteoblasts in vitro (proliferation, vitality, morphology and cytochemical/immunolabelling of actin and vinculin). Higher cell proliferation rates were found in SiO 2–TiO 2 and TiO 2, and lower in Nb 2O 5 and SiO 2; whereas the vitality rates increased for cp-Ti and Nb 2O 5. Cytochemical assays showed that all substrates induced a normal cytoskeleton and well-developed focal adhesion contacts. SEM revealed good cell attachment for all coating layers. In conclusion, the sol–gel-derived oxide layers were thin, pure and nanostructured; consequent different osteoblast responses to those coatings are explained by the mutual action and coadjustment of different interrelated surface parameters.