Zinc-based Tannin-modified Composite Microparticulate Scaffolds with Balanced Antimicrobial Activity and Osteogenesis for Infected Bone Defect Repair.

Treatment of infected bone defects is a major clinical challenge, bioactive materials combining sufficient antimicrobial activity and favorable osteogenic ability are urgently needed. In this study, through a facile one-pot hydrothermal reaction of zinc acetate in the presence of tannic acid (TA), with or without silver nitrate (AgNO 3 ), was used to synthesize a TA or TA and silver nanoparticles (Ag NPs) bulk-modified zinc oxide (ZnO) (ZnO-TA or ZnO-TA-Ag), which was further composited with zein to fabricate porous microparticulate scaffolds for infected bone defect repair. Bulk TA modification significantly improved the release rate of antibacterial metal ions (Zn 2+ release rate was > 100 times that of ZnO). Fast and long-lasting (>35 d) Zn 2+ and Ag + release guaranteed sufficient antibacterial capability and excellent osteogenic properties in promoting the osteogenic differentiation of bone marrow mesenchymal stem cells and endogenous citric acid production and mineralization and providing considerable immunomodulatory activity in promoting M2 polarization of macrophages. At the same time, synchronously-released TA could scavenge endogenous reactive oxygen species (ROS) and ROS produced by antibacterial metal ions, effectively balancing antibacterial activity and osteogenesis to sufficiently control infection while protecting the surrounding tissue from damage, thus effectively promoting infected bone defect repair. This article is protected by copyright. All rights reserved.