Bioactive inorganic-organic hybrids with deformability

PDMS-CaO-SiO₂-TiO₂ and PTMO-CaO-SiO ₂-TiO₂ hybrids formed bonelike apatite on their surfaces in simulated body fluid (SBF) and showed high deformability. The incorporation of CaO component was essential for them to show high apatite-forming ability in SBF, but CaO-containing hybrids showed a decrease in their mechanical strength by aging in the body environment. A CaO-free PDMS-TiO₂ hybrid, in which the structure of TiO₂ was controlled to be anatase by a hot-water treatment, also showed apatite-forming ability in SBF and high deformability. When PDMS is replaced with PTMO, the obtained PTMO-TiO ₂ hybrid with a hot-water treatment shows apatite-forming ability in SBF and mechanical strength higher than that of the PDMS-TiO₂ hybrid. When TiO₂ is replaced with Ta₂O₅, a CaO-free PTMO-Ta₂O₅ hybrid shows apatite-forming ability in SBF without any treatment, as well as mechanical strength and Young's modulus analogous to those of human cancellous bones. These results indicate that a new kind of bioactive hybrid, which shows mechanical properties analogous to those of human bones and high durability in the body environment, can be obtained by controlling not only the compositions but also the structures of sol-gel-derived inorganic-organic hybrids.