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

HighlightsA PCL/nanocapsule coating was developed on Mg alloy by spin-coating.Pluronic F127 modified nanocapsules enabled ultrasound-triggered drug release.The coating enhanced corrosion resistance and enabled self-healing at 50 °C.The coating showed antibacterial effect and promoted osteogenic differentiation.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 × 10−6to 5.94 × 10−7A/cm2. In vitro biological assays confirm the antibacterial efficacy againstStaphylococcus aureusandEscherichia 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.