Bioactive nano-structured silica-based hybrid coatings prepared by sol-gel on stainless steel 316L for prosthetic devices: in vitro and in vivo study

J. BALLARRE,; INDERCHAND MANJUBALA; WIDO H. SCHREINER; JUAN CARLOS ORELLANO; PETER FRATZL; SILVIA CERÉ

ACTA BIOMATERIALIA

ELSEVIER SCI LTD

Año: 2010 vol. 6 p. 1742 - 7061

1742-7061

In this study, we report a hybrid organic–inorganic TEOS–MTES (tetraethylorthosilicate–methyltriethoxysilane)sol–gel-made coating as a potential solution to improve the in vivo performance of AISI 316Lstainless steel, which is used as permanent bone implant material. These coatings act as barriers forion migration, promoting the bioactivity of the implant surface. The addition of SiO2 colloidal particlesto the TEOS–MTES sol (10 or 30 mol.%) leads to thicker films and also acts as a film reinforcement. Also,the addition of bioactive glass–ceramic particles is considered responsible for enhancing osseointegration.In vitro assays for bioactivity in simulated body fluid showed the presence of crystalline hydroxyapatite(HA) crystals on the surface of the double coating with 10 mol.% SiO2 samples on stainless steelafter 30 days of immersion. The HA crystal lattice parameters are slightly different from stoichiometricHA. In vivo implantation experiments were carried out in a rat model to observe the osteointegrationof the coated implants. The coatings promote the development of newly formed bone in the peripheryof the implant, in both the remodellation zone and the marrow zone. The quality of the newly formedbone was assessed for mechanical and structural integrity by nanoindentation and small-angle X-rayscattering experiments. The different amount of colloidal silica present in the inner layer of the coatingslightly affects the material quality of the newly formed bone but the nanoindentation results reveal thatthe lower amount of silica in the coating leads to mechanical properties similar to cortical bone.