Sol–gel modification of silicone to induce apatite-forming ability

Silicones formed with silanol groups on their surfaces were prepared by partial hydrolysis and polycondensation of tetraethoxysilane (TEOS) dispersed in silicones in molecular scale. Although the silanol-modified silicones thus prepared formed no apatite in a simulated body fluid (SBF) with ion concentrations nearly equal to those of human blood plasma within 21 d, they formed a bone-like apatite layer in situ on their surfaces in a solution (1.5 SBF) with ion concentrations 1.5 times the SBF within 7 d. This indicates that the silanol groups formed on the silicones by the present method can induce the apatite nucleation in 1.5 SBF and hence, apatite-coated silicones can be fabricated by a biomimetic process. Apatite–silicone composites thus prepared could exhibit mechanical properties analogous to the natural bone as well as bioactivity.