Interfacial diffusion regulation via a self-reinforcing MgO/sodium alginate/gallium hybrid coating on magnesium for enhanced tissue-induced regeneration

For guided bone regeneration (GBR) membranes, biodegradable magnesium has emerged as a highly promising candidate owing to its intrinsic biofunctionality associated with Mg 2+ release and its superior mechanical properties. However, achieving spatiotemporally controlled degradation that precisely matches the kinetics of new bone formation remains a critical challenge. To address this issue, a self-reinforcing interfacial diffusion system was engineered on magnesium in this study. Based on this concept, a multilayered magnesium oxide (MgO)/sodium alginate (SA) composite coating was fabricated and stabilized via Ga 3+ -mediated coordination and ionic crosslinking. This coating was strategically designed as a three-dimensional barrier to govern Mg 2+ release through diffusion-limited transport across the solid–hydrogel interface. Notably, during degradation, the released Mg 2+ dynamically coordinate with SA chains on top of the pre-existing trivalent ion-mediated crosslinked network, triggering progressive hydrogel network densification and consequent in situ formation of a self-reinforcing protective layer. Comprehensive in vitro biological evaluations demonstrate that the coating exerts multifunctional bioactivity via synergistic release of Mg 2+ and Ga 3+ . Specifically, it enhances osteogenic differentiation and proliferation of osteoblast, while also promoting human umbilical vein endothelial cell proliferation, migration, and tube formation for pro-angiogenic capacity. Furthermore, the sustained, low-dose release of Ga 3+ endows the system with broad-spectrum antibacterial activity. By integrating corrosion resistance, osteogenesis, pro-angiogenic functionality and antibacterial efficacy into a single dynamic platform, this system transcends conventional passive barrier strategies and enables active, biology-informed regulation of the regenerative microenvironment. Consequently, it establishes a robust and translational foundation for next-generation magnesium-based GBR membranes, with strong potential for clinical application in oral and maxillofacial bone reconstruction.