Silver‐loaded polydopamine coating mediated dual‐mode antibacterial and biological response for composite scaffolds

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How to endow bone scaffolds with excellent antibacterial properties to fight bone implant‐related infections, while maintaining biocompatibility, remains a challenging issue. In this study, we constructed a polymer/ceramic composite bone scaffold composed of polylactic acid/boron nitride/zinc oxide (PLA/BN/ZnO, PBZ) with a silver‐loaded polydopamine (PDA‐Ag) coating by combining fused deposition modeling (FDM) 3D printing with mussel‐inspired in situ growth techniques, aiming to achieve dual‐mode antibacterial functionality and favorable biological properties. Morphology, phase, and functional group characterization analysis indicated that dopamine undergoes oxidative self‐polymerization to form a polydopamine coating on the PBZ scaffold surface and generates silver nanoparticles (AgNPs) within the coating via chelation and reduction of Ag + by phenolic hydroxyl groups. Photothermal response testing indicated that the PDA‐Ag coating imparted excellent photothermal properties to the PBZ scaffold, with equilibrium temperatures reaching 60°C–80°C in wet conditions, depending on Ag + concentration and near‐infrared laser (NIR) power density. Ion release tests showed that the coated scaffold achieved sustained Ag + release for over 21 days. Antibacterial results showed the coated scaffold blocked over 90% of Gram‐positive and Gram‐negative bacteria, combining the ion release‐mediated antibacterial effect of AgNPs and the photothermal effect‐driven antibacterial action of AgNPs and polydopamine. Cell culture tests confirmed biocompatibility of the antibacterial scaffold, due to the cell affinity improved by the rich functional groups and hydrophilicity of polydopamine. This study proposes a solution for infectious bone defects using 3D printing, in situ surface growth, and optimized design to produce scaffolds with dual antibacterial modes (ion release and photothermal‐mediated) and enhanced biological properties.