Polydopamine-Modified Composite Bone Cement for Cancellous Bone Repair: Synergism of Bioactivity, Antibacterial Properties, and Biodegradability

Infection-prone bone defects require multifunctional materials. We developed a novel degradable composite bone cement: polydopamine-modified calcium polyphosphate (CPP@PDA) combined with tricalcium silicate (C₃S). CPP@PDA provides bioactivity and antibacterial effects, while C₃S ensures sustained bioactive ion release. The cement exhibited >74% antibacterial efficacy (<i>Staphylococcus aureus</i>, <i>Escherichia coli</i>), with bacterial survival at 15.9 ± 1.2% and 26.1 ± 0.8%. Controlled degradation released Ca²⁺ and silicon species, stimulating osteogenesis, shown by increased alkaline phosphatase (ALP) activity and upregulated <i>RUNX2</i>, <i>COL1</i>, and <i>OPN</i> markers. The material also demonstrated antioxidant and antiinflammatory properties, reducing oxidative stress and modulating immune responses to support bone regeneration. This CPP@PDA composite cement, with synergistic antibacterial, biodegradable, and osteogenic functionalities, shows significant potential for treating infection-prone cancellous bone defects.