Synergistic effects of bioactive glass and sodium alginate on the surface properties and therapeutic release of ciprofloxacin from apatite cements

This work aims to investigate the effect of the incorporation of additives, including 46S6 bioactive glass (BG) and sodium alginate polymer (Alg), on the adsorption behavior, drug release kinetics, in vitro degradability, antibacterial activity, cytotoxicity, and inflammatory response of ciprofloxacin (Cip)-loaded reference cement (RC). Microstructural analysis revealed that the addition of BG and Alg to the reference cement composition (DCPD-CaCO₃) significantly affected its specific surface area, porosity, surface charge, and the pH of the cement pastes, as well as the solubility of ciprofloxacin within the cement matrix. The adsorption and release behaviors of ciprofloxacin were examined in relation to these modified cement properties and the physicochemical characteristics of ciprofloxacin. The results revealed that the adsorption process was mainly governed by a Freundlich-type isotherm, which is characterized by a low affinity between the Cip molecules and the carrier surface. Moreover, the results of the antibiotic release showed that antibiotic release is influenced mainly by the pH and solubility of Cip. Depending on the composition of the cement, the release follows mechanisms driven by Fick's law of diffusion alone or in combination with other mechanisms. The in vitro biodegradation test of the prepared cements in phosphate buffer solution attested that adding BG and alginate improved the degradability of the reference cement. Moreover, the formulated cements exhibited good antibacterial activity against Staphylococcus aureus and Escherichia coli. Finally, the in vitro investigation revealed the non-cytotoxicity and non-inflammatory effects of the ciprofloxacin-loaded cements towards hPBMCs cells, confirming their biocompatibility.