There are currently no biomaterials that can 100% mimic the functions of living tissues. Sol-gel derived bioactive glasses (SiO2-CaO-P2O5) bond with bone through formation of a hydroxycarbonate apatite (HCA) layer and are bioresorbable, releasing ions that can stimulate bone regeneration at genetic level. Here, structural analysis showed that hydroxyapatite (HA) formed within the glass, during sol-gel processing, due to orthophosphate units being formed after hydrolysis of the phosphate precursor.
The first aim was to produce a sol-gel bioactive glass that contains no pre-formed HA but with good bioactivity. Increasing the P2O5 to CaO ratio caused the formation of a phosphate glass network. Glass is brittle and cannot be used when a bone defect is subjected to cyclic loads. A second aim was to synthesise an inorganic/organic hybrid from the new sol-gel glass and polycaprolactone (PCL), which has lower stiffness and is bioresorbable. Calcium methoxyethoxide (CME) was investigated as an alternative precursor to incorporate calcium into the inorganic network of the hybrids at room temperature. The hybrid improved the mechanical properties over sol-gel glass. HCA formed on the surface of PCL hybrids just after 3 days of simulated body fluid (SBF) immersion. Cell culture study also showed the PCL hybrids could support good cell attachment and passed ISO standard cytotoxicity test. 3-D printing PCL hybrid scaffold was possible but challenging.