Gelatin/chitosan coating-embedded ZIF-8@DFO on Zn-EGCG: An effective strategy for treating infected bone defects

Titanium-based bone defect repair often encounters problems such as bacterial infection and excessive inflammation. In this study, firstly, tea polyphenol and zinc ion (E-Zn) coatings were prepared on titanium surface. Subsequently, ZIF8@D (ZIF8 loaded with desferrioxamine) was loaded onto the E-Zn surface with the help of gelatin and chitosan (CG) to form an E-Zn/CG-ZIF8@D composite coating. The results demonstrated that the E-Zn/CG-ZIF8@D coating exhibited favorable hydrophilicity, corrosion resistance, and hemocompatible. In vitro, the coating boasted outstanding antimicrobial properties due to the antimicrobial effects of Zn²⁺ against E. coli and S. aureus. Leveraging the anti-inflammatory properties of Zn²⁺, the coating could modulate the polarization of macrophages (RAW264.7) to the M2 type. Thanks to the vascularization-inducing properties of desferrioxamine, the coating could prompt the vascularization of human umbilical vein endothelial cells (HUVEC). Relying on the osteogenic properties of Zn²⁺, the coating could drive the differentiation of preosteoblasts (MC3T3-E1) towards osteogenesis. In vivo experiments indicated that the E-Zn/CG-ZIF8@D manifested excellent anti-inflammatory, antibacterial, angiogenic, and bone repair capabilities. This surface engineering strategy is highly effective. It constructs favorable bone-implant interfaces. It does this by integrating multiple functions. As a result, the likelihood of implant failure is significantly reduced.