Self-Healing Coating with Ultrasound-Triggered On-Demand Osthole Release for Magnesium-Based Orthopedic Implants

Magnesium alloys exhibit promising application prospects in medical orthopedic implants. However, their practical applications are limited by rapid corrosion, suboptimal osseointegration, and implant-related infections. Although conventional drug-eluting polymer coatings can provide various biological functions, the uncontrolled drug release often compromises long-term therapeutic efficacy. In this study, a self-healing Mg-poly(ε-caprolactone) (PCL)@OHF coating is designed and prepared on WE43 Mg by spin coating to achieve ultrasound-triggered release of osthole. OHF consists of osthole-loaded hollow mesoporous silica nanoparticles (HMSs) modified with Pluronic F127. Drug release studies show that the nanocapsules respond to ultrasound stimulation, with the cumulative release increasing from 39.94% to 75.93% after 7 days. Furthermore, the coating demonstrates intrinsic self-healing capacity upon thermal treatment at 50 °C. Electrochemical and immersion tests reveal that the composite coating provides good barrier protection for the WE43 Mg alloy, evidenced by a decrease in corrosion current density from 2.04 × 10−6 to 5.94 × 10−7 A/cm2. In vitro biological assays confirm the antibacterial efficacy against Staphylococcus aureus and Escherichia coli, as well as the ability to promote osteogenic differentiation. The results reveal a surface modification strategy that combines self-healing, anticorrosion, and on-demand drug release, offering a promising approach for advanced orthopedic implants.