Self-assembly LDHs nanosheets/silk fibroin multilayer coating with enhanced biocompatibility, photothermal antimicrobial activity, and self-healing property

Rapid corrosion and bacterial infection are obstacles to the utilization of biodegradable magnesium alloys as biomedical materials. In this study, a polydopamine (PDA)/silk proteins (SF)-coated ternary Mg-Al-La layered double hydroxides (LDHs) coating (TLDHs-PDA-SF coating) prepared on the magnesium alloy surface by self-assembly method was proposed. The TLDHs-PDA-SF coating exhibited good self-healing, antimicrobial activity (especially under 808 nm irradiation), and biocompatibility. This heterogeneous coating can quickly self-heal within 24 h and inhibit cathodic corrosion due to the interference of rare earth cations with local alkalinization and the spontaneous polymerization of PDA. Due to the synergistic effect of the photosensitivity of PDA and the thermal insulation of SF, it has good bactericidal properties against Staphylococcus aureus (S. aureus) under near-infrared (NIR) irradiation, and the antibacterial rate reaches 98.71 %. In vitro results showed that SF and PDA could enhance L929 cytocompatibility, with more than 100.2 % cell viability. This work provides a strategy for the preparation of composite coatings on magnesium-based implants with the triple functions of antimicrobial capacity, self-healing, and biocompatibility.