A microenvironment responsive polyetheretherketone implant with antibacterial and osteoimmunomodulatory properties facilitates osseointegration

Failure of intraosseous prostheses is primarily attributed to implant loosening and infections. Current primary therapeutic modalities, such as antibiotics and local debridement, not only face challenges in thoroughly eliminating obstinate adhered bacteria but also encounter difficulties in ameliorating undue inflammatory reactions and regenerating impaired peri-implant bone tissues. Polyetheretherketone (PEEK) has excellent mechanical and physicochemical characteristics and has been used extensively as a medical biomaterial. However, the limited bactericidal and osseointegrative activities of bioinert PEEK restrict its clinical application. Herein, a microenvironment responsive coating with immobilised immunomodulatory magnesium ions (Mg²⁺) and disinfectant cerium oxide nanoparticles (CNPs) is designed via ion coordination mediated by polydopamine (PDA) and electrospinning based on collagen structure-bionic silk fibroin (SF). By utilising the pH responsiveness of SF, CNPs exhibit potent antibacterial effects in an acidic environment (pH 5.0) caused by local bacterial infection. Due to the chelation interaction with PDA and the constraint of SF, Mg²⁺ is slowly released, ameliorating the local immune microenvironment and boosting osteogenesis by upregulating M2 phenotype macrophages. Bioinformatics analysis indicates that the inflammation is suppressed via the NF-κB signaling pathway. Overall, this SF-based coating maximizes the synergistic effect of CNPs and Mg²⁺, offering enhanced antibacterial and osteoimmunomodulatory bioactivity for successful implantation.