Endowing calcium phosphate ceramics with long-acting antibacterial capacity by constructing multilevel antibiotic release structure for regenerative repair of infected bone defect

Long-acting antibacterial captivity and rapid osteogenic ability are two key factors to achieve the regenerative repair of infected bone defect. Although calcium phosphate (CaP) ceramics possess excellent osteoinductivity and have been widely employed in bone defects repair, the development of CaP ceramics with long-acting antibacterial capacity remains a big challenge. In this study, the in-situ hollow-tube whiskers were constructed to serve as drug loading sites, which could endow CaP ceramics with sustained antibiotic release capacity. Comparing with the conventional CaP ceramics (CBCP), in-situ hollow-tube whiskers modified CaP ceramics (HWBCP) possessed large specific surface area and high microporosity, which could be conductive to the antibiotic adsorption. Furthermore, CaP ceramics with in-situ hollow-tube whiskers could achieve enhanced sustained-release ability of antibiotics after quaternized chitosan (QCS) coating. Especially for ciprofloxacin, the releasing duration can last over 60 days, and the long-acting antibacterial activity is also confirmed. In vivo infected femoral condyle defect experiments certified that the bacteria were completely inhibited at the early stage and the infected bone defects were superiorly repaired at 8 weeks postoperatively. Collectively, the strategy of constructing hollow-tube whiskers in CaP ceramics with sustained release of antibiotics could provide a promising therapy for the regenerative repair of infected bone defect.