Baicalin-Ternary LDH-Modified Magnesium Alloy with Anti-Corrosion and pH-Responsive Controlled Release, Near-Infrared-Enhanced Catalytic Property

Aiming at the rapid corrosion of degradable magnesium alloys in physiological environments and the insufficient long-term protection of single plasma electrolytic oxidation (PEO) coatings, Mg-Mn-Fe layered double hydroxide (LDH) and baicalin (BA)-loaded LDH/BA composite coatings were prepared in situ on PEO-pretreated ZE21C magnesium alloy substrates. BA was stably anchored on the LDH surface via coordination bonds between its oxygen-containing functional groups and laminate metal sites. Benefiting from the physical barrier of the LDH lamellar structure and the corrosion inhibition effect of baicalin, the LDH/BA coating significantly improved the corrosion resistance of the magnesium alloy matrix. The composite coating exhibited peroxidase-like catalytic activity for reactive oxygen species generation, which could be enhanced by near-infrared irradiation. It also possessed stable photothermal conversion performance and pH-responsive drug release behavior under acidic conditions. Biological characterization demonstrated that BA-loaded LDH composite coatings exert potent inhibitory effects on 143B cell proliferation. This work integrates long-term corrosion resistance, controlled drug release, and photoresponsive catalytic functions onto magnesium alloy surfaces, providing an effective strategy for developing high-performance biodegradable magnesium alloys.