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

HighlightsWhat are the main findings?The Mg-Mn-Fe LDH grown in situ on the PEO coating-modified Mg alloy effectively blocks pores and introduces metal catalytic active sites.Baicalin achieves stable immobilization by forming coordination bonds with the metal ions in LDH through the oxygen-containing functional groups.The LDH/BA composite coating significantly improved corrosion resistance, along with pH-responsive drug release and near-infrared-enhanced enzyme-like catalytic performance.What are the implications of the main findings?A multi-functional modification strategy integrating “corrosion resistance, drug loading and control release” was established, which provides a novel technical solution for the long-term corrosion protection of magnesium alloys.The revealed interfacial coordination immobilization mechanism can provide theoretical references for the structural design of organic–inorganic composite protective coatings.The synergy of corrosion resistance and microenvironment stimulus-responsive functions is realized, which expands the application of LDH coatings in the modification of metal implants.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.