Synergistic antibacterial and osteogenic properties of micro-arc oxidation GO@Ag/SF composite coatings for the repair of infectious bone defects

Background: Bacterial infection and insufficient osseointegration of titanium-based implants remain major clinical challenges. Conventional drug-loaded coatings often fail to simultaneously achieve long-term antibacterial activity and the construction of an osteogenic microenvironment.Methods: In this study, a graphene oxide-supported silver nanoparticle/silk fibroin (GO@Ag/SF) composite coating was developed and modified via micro-arc oxidation. By precisely controlling the GO/AgNO₃ volume ratio, the antibacterial and osteogenic performances of the coatings were systematically evaluated. A rat model of infectious bone defect was employed to verify the in vivo therapeutic efficacy.Results: The optimized GO@Ag/SF coating exhibited: (i) pH-responsive Ag⁺ sustained release (0.23 μg/mL cumulative release over 672 h, increased to 0.69 μg/mL under acidic conditions); (ii) NIR-enhanced antibacterial efficacy (inhibition rates against S. aureus and E. coli reaching 98.3 ± 1.2%); (iii) significantly enhanced in vitro osteogenic activity (2.1-fold increase in ALP activity and 178% increase in calcium nodule density); and (iv) improved in vivo bone volume fraction (BVF increased to 17.13% compared to 9.83% in the control group).Conclusion: Through the synergistic effects of its components, the GO@Ag/SF coating established a dynamic antibacterial-osteogenic balance, offering a promising strategy for the repair of infectious bone defects.