Microvoid-sealed ZnO-bridged LDH nanosheets for sustained dual protection of Mg alloys

Rapid degradation and susceptibility to infection significantly limit the clinical application of magnesium alloys. To address these challenges, the unique architecture, in situ grown zinc oxide (ZnO) nanorods to bridge microvoids within the layered double hydroxides (LDH) matrix, was constructed on AZ31B magnesium alloy via a two-step hydrothermal method. This unique design utilizes in situ grown ZnO nanorods to effectively seal the inherent microvoids within the LDH matrix, creating a dense nanoscale barrier. Consequently, the Mg/LDH@ZnO coating exhibits superior corrosion resistance, with a significantly lower corrosion current density of 0.3 ± 0.1 μA·cm−2 and a high charge-transfer resistance of 1.5 × 107 Ω⋅cm2, ensuring long-term protection (99% suppressed hydrogen evolution versus bare Mg). Furthermore, the composite coating achieves potent antibacterial efficacy with an 87.9% inhibition rate against bacteria. This functionality relies on the sustained release of zinc rather than the rapid sacrifice of the substrate, thereby maintaining structural integrity while preventing infection. This work presents a robust strategy for developing biodegradable implants with synergistic corrosion resistance and antibacterial properties.