Functionalized-nanoparticles/silk fibroin coating with anti-adhesive and photothermal capabilities to prevent implant-associated infections

Antibacterial coatings that can firstly prevent bacterial adhesion and then kill the attached bacteria are urgently required for combat of implant-associated infections. However, current surface strategies are limited by complicated preparation, uncontrolled-release of antimicrobials, and low biocompatibility. Here, we developed a dual-functional, antibacterial coating by functionalizing iron oxide nanoparticles (FNP) with polydopamine and polyethylene glycol, respectively and then depositing them with silk fibroin (SF) on a titanium substrate (FNP/SF-Ti). This surface strategy is facile to achieve and widely adapted to any nanoparticles and substrates. In an optimized SF coating density, the FNP/SF-Ti surface reduced bacterial adhesion for more than 100 folds to both Methicillin-resistant Staphylococcus aureus and Escherichia coli to compare with bare Ti surface. Under near-infrared (NIR) light irradiation, the attached bacteria on FNP/SF-Ti surface were totally killed in a photo-controllable way and no biofilm formed subsequently. The in vitro biocompatibility and osteogenic effect of FNP/SF-Ti surface was better than bare Ti and FNP-Ti surface. In a rat sub-cutaneous model, MRSA infections on FNP/SF coated Ti discs were effectively inhibited due to the synergistically effect of anti-adhesive and photothermal performances. In a rat bone-defect model, MRSA-contaminated FNP/SF-Ti rods were disinfected by NIR irradiation after implantation and the osteogenesis on FNP/SF-Ti rods were not affected by MRSA infection. Therefore, the FNP/SF coating is a potential surface treatment strategy to prevent implant-associated infections.