Construction of Antimicrobial Material-Loaded Porous Tricalcium Phosphate Beads for Treatment of Bone Infections

Due to low success rates of antibiotic therapy in most osteomyelitis diseases, continuous efforts have been made to fabricate local delivery systems with high antimicrobial effects. Here, we reported a kind of ε-polylysine­(PL)/Ag-loaded porous tricalcium phosphate (TCP) bead instead of antibiotics as local delivery systems for the treatment of Staphylococcus aureus-caused osteomyelitis. Such local delivery systems were prepared by the fabrication of porous TCP beads at first and then the loading of Ag and PL in turn into porous TCP beads via in situ Ag-doping and layer-by-layer methods. In vitro experiments demonstrated that the release of PL and Ag was controllable. Especially, the release dosage of Ag could be controlled to be less than 0.05 ppm 28 days later. The surface coating of PL improved the cytocompatibility and antibacterial activity of local delivery systems. In vivo experiments demonstrated that the Ag/PL-loaded porous TCP beads displayed strong antibacterial activity and good osteoconductivity, and the combination of Ag and PL was better than the use of single antibacterial materials to treat S. aureus-caused osteomyelitis. The implantation of Ag into the infected marrow had low toxicity because Ag has been integrated into the TCP grains, which could be absorbed in marrow. Therefore, the Ag/PL-loaded porous TCP beads presented potential for treating osteomyelitis, especially sequestrum-debrided osteomyelitis.