Synthesis of a bi-structured hybrid in a CaO–SiO2-PTMO system and in vitro evaluation on its potential of bone-bonding property

Organically modified silicates incorporated with calcium salts produce novel, bioactive materials, which bond directly to living bone, because after exposure to a physical environment, calcium silicates have a high hydroxyapatite-deposit potential. In this study, transparent, monolithic, bi-structured hybrids were prepared using a sol–gel process for the CaO–SiO2-PTMO system. To establish the bi-structure, two types of sols were prepared: a polymer-rich sol that had a starting composition of PTMO/TEOS in an 80/20 mass ratio and a ceramic-rich sol that had a starting composition of TEOS/Ca(NO3)2 in a 1/0.3 molar ratio. The bi-structured hybrid was synthesized using a gelation process, where the ceramic-rich sol was placed on the polymer-rich wet gel. An interfacial structure with tight binding was established between the two gels that had the potential to form calcium phosphate within a period of 6 h on the bi-structured hybrid. This process led to the successful synthesis of a bi-structured hybrid with a high potential for bone-bonding property, which was also flexible.