Magnesium (Mg)-based barrier membranes demonstrate significant potential as biomaterials for guided bone regeneration, thereby potentially broadening the scope of clinical applications. However, the interaction between Mg-based implants and the human oral microbiome remains poorly understood. This in situ human study investigated the bidirectional interactions between pure Mg and the human oral microbiome using a personalized oral device. The results demonstrated that Mg-bacteria interactions induce spatially heterogeneous corrosion layers characterized by biomineralized precipitates and organic-matrix integration. Dynamic salivary flow and biofilm-mediated diffusion barrier synergistically promoted uniform electrochemical degradation and suppressed localized pitting corrosion. Although pure Mg exhibited antimicrobial effects under in vitro conditions, its in vivo bacteriostatic effect was attenuated by salivary sequestration of Mg-based surface and biofilm maturation. This led to inter-individual variability in microbial colonization of the biomaterial. Also, Streptococcus spp. were the dominant colonizers, and this pattern was influenced by acquired pellicle and salivary flow. These findings elucidate the critical role of the human oral microbiome in modulating Mg corrosion pathways, providing insights for the rational design of Mg-based implants for dental applications.

Biodegradable magnesium (Mg) and its alloys exhibit excellent biocompatibility and mechanical compatibility, demonstrating tremendous potential for applications in orthopedics. However, the rapid degradation rate has limited their clinical application. Polycaprolactone (PCL) is commonly employed as a polymer coating to impede the rapid degradation of Mg. Unfortunately, its long-term anti-corrosion capability and bioactivity are inadequate. To address these issues, polydopamine (PDA)-modified zeolitic imidazolate framework-8 (PZIF-8) bioactive nanoparticles are fabricated and incorporated into the PCL coating. The PZIF-8 particles, featuring catechol motifs, can enhance the compactness of the PCL coating, reduce its defects, and possess biomineralization ability, thereby effectively improving its anti-corrosive and bioactive properties. Moreover, the active substances released from the degradation of the PZIF-8 particles such as Zn²⁺ and PDA are beneficial for osteogenesis. The corrosion tests indicate that the corrosion current density of PCL-treated sample decreases by more than one order of magnitude and the amount of H₂ released decreases from 0.23 ± 0.12 to 0.08 ± 0.08 ml cm⁻² after doping with the PZIF-8. Furthermore, the improved corrosion resistance and released PDA and Zn²⁺ from the coating can promote osteogenic differentiation by up-regulating the expression of alkaline phosphatase activity, related osteogenic genes, and proteins. In addition, in vivo implantation experiments in rabbit femur defects further offer strong evidence that the doping of PZIF-8 nanoparticles accelerates bone reconstruction of the PCL coating. In summary, this work implies a new strategy to fabricate a PCL-based coating on Mg-based implants by introducing the PZIF-8 particles for orthopedic applications.