Influence of a SiO2-CaO-P2O5 sol-gel glass on the bioactivity and controlled release of ceramic/polymer/antibiotic mixed materials

Materials based on ceramic-polymer-gentamicine blends with potential application as prefabricated bone blocks and drug delivery systems have been synthesized. Three series of materials have been prepared with varying composition of the ceramic fraction. The ceramic component of series S1 contains only hydroxiapatite (HA), series S2 contains HA and 2.7% sol-gel glass, and series S3 contains 29% glass. Series S3 develops an apatite-like phase on the surface when soaked in simulated body fluid (SBF). Series S2 undergoes surface changes, but the development of an apatite-like phase does not occur. Finally, series S1 does not exhibit significant changes at the surface. Materials with 29% glass show an important surface area reduction during the first 24 h due to the formation of an amorphous calcium phosphate before the OHAp crystallization. This surface reduction leads to a retardation of the drug release during this period compared to the samples with no glass or 2.7% glass. The results presented in this work point out that when synthesizing bioactive materials to be used as drug delivery systems, the important surface modifications must be considered for the drug release kinetics.