Bioactive nanoparticle through postmodification of colloidal silica.

Bioactive nanoparticles with controllable size and good colloidal stability were synthesized through surface modification of colloidal silica nanoparticles with Ca(OH)2 as the modifier. These modified nanoparticles showed good bioactivity, showing evidence of hydroxyapatite formation when incubated in simulated body fluid within 3 days. Comparison of bioactivity was made among different sized particles from nanoscale to microscale. It was found the bioactivity of these calcium modified colloidal silica particles generally decreased with particle size in the explored size range (40 nm particles showed bioactivity within 1 day). These particles were also found to be noncytotoxic but promote preosteoblast growth, thus making them promising bioactive additives for bone repair materials.