Surface-activated 3D-printed PEEK implant enhances anti-infection and osteogenesis

With the advantage of remarkable mechanical processing ability without losing its strength, polyetheretherketone (PEEK) based medical devices have been drawing great attention in orthopedic treatments. However, its limited osseointegration capacity and susceptibility to bacterial colonization-induced infections pose a considerable risk of implant failure. Current methods of antimicrobial and osteogenic functionalization frequently exhibit conflicting outcomes. The antimicrobial functionalization of implants usually leads to cytotoxicity and histotoxicity, adversely affecting the connection with surrounding tissues, whereas the osteogenic functionalization may inadvertently promote bacterial adhesion and biofilm development. Therefore, it is highly demanded to endow the PEEK implants with antibacterial and osseointegration properties simultaneously. In this study, 3D-printed PEEK implants were surface modified with hyperbranched poly-l-lysine (HBPL) via physisorption (PEEK-a-HBPL) and chemical grafting (PEEK-g-HBPL), respectively, which were demonstrated by attenuated total reflection Fourier transform infrared spectroscopy, water contact angle, and X-ray photoelectron spectroscopy. Remarkably, both the PEEK-a-HBPL and PEEK-g-HBPL exhibited significantly improved antibacterial efficacy against S. aureus and E. coli, while their osteogenesis ability was not affected but even promoted in vitro. In an in vivo bone-infection and implantation model in rats, significantly reduced surrounding tissue inflammation and larger new bone formation were observed in both the PEEK-a-HBPL and PEEK-g-HBPL groups compared to the untreated PEEK group. This comprehensive study lays a foundation for the advancing of organic orthopedic implant materials, offering potential solutions to the pressing issues of osseointegration deficits and implant-related infections.