KR-12 coating of polyetheretherketone (PEEK) surface via polydopamine improves osteointegration and antibacterial activity in vivo
Polyetheretherketone (PEEK) is considered a promising bone implant material owing to its biocompatibility and elastic modulus, which is similar to that of the natural bone. However, the clinical potential of PEEK is severely limited by its bioinertness, such as poor osseointegration and lack of antibacterial property. In this study, the antimicrobial peptide, KR-12, was immobilized on the surface of PEEK implants with the assistance of polydopamine (PDA) to inhibit bacterial infection as well as promote osteogenesis and osseointegration. Compared to unmodified PEEK, the immobilization of KR-12 on PEEK significantly improved the antibacterial activity against Staphylococcus aureus (ATCC 25923), both in vitro and in vivo. To evaluate the osteogenic property of modified PEEK, cell culture of rat bone mesenchymal stem cells (rBMSCs) and a rat femoral defect model were used for in vitro and in vivo evaluation, respectively. The in vitro studies showed that, compared to unmodified PEEK, rBMSCs exhibited improved adhesion, proliferation, and osteogenic differentiation after the immobilization of KR-12 on the PEEK surface. Moreover, micro-computed tomography and histological analysis suggested that the KR-12 coating promoted osteointegration in vivo in rat femur.. Taken together, these results suggest that the KR-12 coating could improve the antibacterial ability of pure or PDA-coated PEEK against Staphylococcus aureus (ATCC 25923), both in vitro and in vivo. Overall, KR-12, combined with the PDA film coating, synergistically induced osteogenic effects both in vitro and in vivo. Thus, the surface-modified material, which exhibits both anti-bacterial and osteointegration properties, shows considerable potential for use as an orthopedic implant.