Bioactivity of PLGA-gel-derived bioglass composites

A series of PLGA (poly L-lactide-co-glycolide) based composites modified with gel-derived glasses in the form of foils were obtained by solvent casting procedure. As a modifier, glass particles with different chemical compositions from the CaO–SiO2, CaO–P2O5–SiO2,and Al2O3–SiO2 systems were used. All glasses were synthesized by the sol-gel process. Evaluation of bioactive properties of obtained composites was made on the basis of surface changes occurring during contact with simulated body fluid. The changes of Ca, P and Si ions concentration in SBF after incubation of composites were also measured. The result showed that all composites with bioglasses (CaO–SiO2, CaO–P2O5–SiO2) exhibit formation of calcium phosphates layer after SBF test, however, kinetics of Ca, Si ion release and P uptake from SBF was dependent on bioglass chemical composition. The higher solubility, as well as faster consumption of phosphorus from SBF, was observed for materials from CaO–SiO2 (T1/PLGA, S1/PLGA) compared to composites with respective bioglass particles from the CaO–P2O5–SiO2(T2/PLGA, S2/PLGA). Our results showed that rate of Si and Ca release from the gel-derived glasses and P uptake from SBF are dependent on both: the concentration of respective ions in the materials and the presence of phosphates in their structure. For materials modified with gel-derived glasses from Al2O3–SiO2 system no significant surface changes during contact with SBF were observed, and it seems that their behavior in physiological solution indicate that they are bio-inert materials.