Evaluation of gentamicin encapsulated hierarchically meso-macroporous silica-based calcium phosphates glass powders

In this study, 80SiO2–15CaO–5P2O5 powders prepared using either a polyurethane foam sponge-F127 co-template (SCP-CoT) or only a polyurethane foam sponge macrotemplate (SCP-T) were used to evaluate the gentamicin encapsulation of hierarchically meso-macroporous silica-based calcium phosphate glass powders. The SCP-CoT powders exhibited an approximately three times larger specific surface area compared to the SCP-T powders. The formation of a hysteresis loop also signified the presence of mesoporous structures in the SCP-CoT powders samples; a hysteresis loop was not observed for the SCP-T samples, which had approximately 1/5 of the pore volume of the SCP-CoT powder samples. The encapsulation capacities of gentamicin for the SCP-CoT and SCP-T powders were 29.4% and 5.4%, respectively, indicating that significantly more gentamicin drug can be loaded into the SCP-CoT powders due to their higher surface area and pore volume. Notably, when the initial gentamicin concentration was 1 mg/ml, the SCP-CoT powder provided a sufficient surface area and pore volume to achieve nearly 100% encapsulation efficiency. Although increasing the initial concentration of gentamicin decreased the encapsulation efficiency, the total amount of encapsulated gentamicin increased. The maximum value of encapsulated gentamicin (39.9 mg/g) was observed at an initial concentration of 50 mg/ml.