Novel bioactive materials: Silica aerogel and hybrid silica aerogel/pseudowollastonite

Abstract

Silica aerogel and hybrid silica aerogel/pseudowollastonite materials were synthesized by controlled hydrolysis of tetraethoxysilane (TEOS) using also methanol (MeOH) and pseudowollastonite particles. The gels obtained were dried using a novel process based on an ambient pressure drying. Hexane and hexamethyl-disilazane (HMDZ) were the solvents used to chemically modify the surface. In order to assess bioactivity, aerogels, without and with pseudowollastonite particles, were immersed in simulated body fluid (SBF) for 7 and 14 days. The hybrid silica aerogel/pseudowollastonite showed a higher bioactivity than that observed for the single silica aerogel. However, as in both cases a lower bioactivity was observed, a biomimetic method was also used to improve it. In this particular method, samples of both materials were immersed in SBF for 7 days followed by their immersion in a more concentrated solution (1.5 SBF) for 14 days. A thick and homogeneous bonelike apatite layer was formed on the biomimetically treated materials. Thus, bioactivity was successfully improved even on the aerogel with no pseudowollastonite particles. As expected, the hybrid silica aerogel/pseudowollastonite particles showed a higher bioactivity.