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

Abstract

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-2/SF coating exhibited pH-responsive sustained Ag+ release, with cumulative release increasing from 0.23 μg/mL under physiological conditions to 0.69 μg/mL under acidic conditions over 672 h. Under NIR irradiation, the coating reached 59.8°C within 10 min and achieved potent antibacterial activity against S. aureus and E. coli, with inhibition rates up to 98.3 ± 1.2%. The GO@Ag-2/SF coating also promoted osteogenic differentiation by enhancing ALP activity, collagen secretion, calcium mineralization, and the expression of RUNX-2, ALP, COL-I, and OCN. In vivo, GO@Ag-2/SF reduced inflammatory infiltration and improved peri-implant bone regeneration, with increased BIC, BV/TV, and Tb.Th and reduced Tb.Sp. Moreover, pull-out testing demonstrated the highest bone-implant mechanical fixation in the GO@Ag-2/SF group, confirming enhanced functional osseointegration in the infected bone defect model. 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.