Biodegradable Mg-Sr/Mg-Ag bilayer membranes enabling integrated osteogenic and antibacterial functions for guided bone regeneration

Biodegradable magnesium (Mg) alloys are promising candidates for guided bone regeneration (GBR) owing to their bone-matched elastic modulus and intrinsic bioactivity. However, simultaneously achieving mechanical robustness, degradation control, and multifunctional bioactivity in a single Mg-based membrane remains a major challenge. Herein, a magnesium-strontium/magnesium-silver (Mg-Sr/Mg-Ag) bilayer GBR membrane is constructed through rational design. Enabled by on-line heating rolling, the metallurgically bonded structure exhibits enhanced mechanical performance (flexural yield strength: 463 ± 9 MPa) while maintaining a stable corrosion rate. More importantly, the spatially resolved configuration enables distinct functional domains: the Sr-containing layer promotes osteogenesis at the bone interface, whereas the Ag-containing layer provides antibacterial protection at the soft-tissue side. The resulting membrane shows approximately 90% broad-spectrum antibacterial efficacy in vitro and significantly accelerates bone regeneration in vivo, with a bone volume fraction of 57.53 ± 4.82% at 8 weeks. Transcriptomic analysis of single alloy extracts suggests that Sr-containing cues are associated with Wnt-related osteogenic programs, whereas Ag-containing cues are associated with integrin-related cell adhesion and matrix-remodeling responses. These findings establish a metallurgically bonded bilayer Mg-alloy membrane that couples osteogenic ion delivery with antibacterial protection, providing a structurally stable and biologically programmed strategy for bone-soft tissue interface regeneration in GBR.