Nanostructure and Bioactivity of Hybrid Aerogels

Abstract

Hybrid sono-aerogels in the CaO−SiO 2 −poly(dimethyl siloxane) (PDMS) system with low density and high surface area and pore volume were investigated to be used as biomaterials. Their in vitro bioactivity was monitored by soaking in a simulated body fluid (SBF). All the aerogels exhibited similar wetting and dissolution properties, but only the aerogel of composition 20 wt % PDMS−20 wt % CaO (S20Ca20) exhibited a bioactive response in SBF. To investigate the relationship between the different in vitro behaviours and the hybrids nanostructure, samples were studied by high-resolution transmission electron microscopy (HRTEM). All the aerogels showed similar basic microstructural features exhibiting amorphous Ca-free areas characterized by Si−O−Si distances of 0.23 nm. However, crystallized nanodomains containing calcium were also detected in S20Ca20. These domains, identified as pseudowollastonite and other Ca−Si−O phases, could explain the bioactive response of this material. Bioactivity and good textural and mechanical properties turn S20Ca20 aerogel into a candidate as biomaterial.