Bioactive and degradable organic–inorganic hybrids

CaO–SiO2–poly(vinyl alcohol) (PVAL) and CaO–P2O5–SiO2–PVAL organic–inorganic hybrids were obtained as monoliths and characterized before and after be soaked in a solution mimicking human plasma. The hybrids were obtained by adding PVAL (0.9, 1.8 and 3.6 wt.%) to three CaO–(P2O5)–SiO2 gel glasses with 25 mol% of CaO and 0, 2.5 and 5 mol%, respectively of P2O5. The influence of PVAL and P2O5 on the monoliths obtaining and on their textural properties and in vitro behavior was analyzed. Additions of PVAL favored the synthesis of cracked-free monoliths able to be coated with bone-like apatite after be soaked in Kokubo's simulated body fluid (SBF), i.e. to present in vitro bioactivity. Increasing P2O5 contents made the hybrids syntheses difficult and decreased their in vitro bioactivity. In addition, the in vitro degradation of hybrids increased with the increasing of PVAL and P2O5. Thus, hybrids with the highest amounts of both components showed so high degradation in SBF that the apatite layer formation was impeded. Organic–inorganic hybrids in these systems could be clinically used as bone defect fillers in non load bearing applications or as matrices in controlled release systems.