Delivery of sodium fusidate from alginate-reinforced, carbonated apatite cement: Physicochemical properties, release behavior, antibacterial and cytotoxicity properties

The present work focuses on the development of composite cements based on dicalcium phosphate dihydrate (DCPD), calcium carbonate CaCO₃, sodium alginate (AG), and sodium fusidate (FS). The effect of AG, setting accelerator (0.5 M of Na₂HPO₄), and antibacterial agent (FS) on the features (setting ability, injectability, cohesion, and compressive strength) of DCPD-CaCO₃-based cement was investigated. The reference and composite cements are composed of a nanocrystalline carbonated apatite, similar to bone mineral, and an excess of unreacted vaterite (CaCO₃). The incorporation of AG increased the composite cement's total porosity compared to the reference cement (CR). The evaluation of the injectability and cohesion properties showed that adding 10 wt % of AG resulted in a total extrusion of the paste with an improvement in the cohesion of the cement paste. The compressive strength of the cements raised from 3.2 for CR up to 7 MPa with the addition of 10 % of AG and Na₂HPO₄ . The setting time is significantly reduced by introducing Na₂HPO₄, resulting in appropriate values (≤ 30 min) for clinical use. Moreover, incorporating 3 wt % of FS in the composite cements had no significant effect on their features. The release study of FS-loaded composites showed sustained and controlled release profiles, with daily released amounts at the therapeutic level. The antibacterial activity of the designed FS-loaded composites demonstrated the effectiveness of the specimens in inhibiting the growth of S. Aureus. Furthermore, the in vitro biological tests did not show any toxicity of the tested cements towards hPBMCs, thereby confirming their biocompatibility.