Synthesis and Evaluation of Novel Glass Ceramics as Drug Delivery Systems in Osteomyelitis

Abstract

In this study, a new generation of bioactive glass ceramics were developed using the wet chemical method. The synthetic conditions were strictly controlled to obtain the materials of a nanometric scale. As evaluated by scanning electron microscopy, bone-like apatite layers were produced in large amounts and completely covered their surfaces after immersion in phosphate buffer saline. On the basis of X-ray diffraction, X-ray fluorescence, and Fourier transform infrared spectroscopy results, PO₄³⁻ groups of hydroxyapatite (HA) were partially substituted by SiO₄⁴⁻ species. The defective chemical structures introduced provided materials that were more biologically active, compared with the parent HA. For effective treatment of infected bones, scaffolds containing the bioactive ceramics were prepared by chitosan cross-linking, and loaded with vancomycin (VCM). The drug-loaded scaffolds were not toxic to bone cells. About 75%-80% of the entrapped drug was released in a controlled pattern and the release was sustained over a 12-day period. The concentration of drug released was determined to be above 20 times the half maximal effective concentration of VCM on Staphylococcus aureus, and was sufficient for killing bacteria growing as biofilm. In summary, the synthesized bioceramics exhibited many of properties associated with an ideal material for implantable drug delivery system, and were suitable for testing the ability to cure bone diseases including osteomyelitis.