Multifunctional PEEK implants via mussel adhesion-mediated assembly for osteoimmune regulation and antibacterial properties

Introduction Polyetheretherketone (PEEK) is widely recognized for its exceptional mechanical properties and biocompatibility, making it a promising material for orthopedic implants. However, its inherent biological inertia—characterized by poor osteogenic potential, limited antibacterial activity, and excessive immune activation—compromises its clinical performance. Methods To address these limitations, we developed a multifunctional PEEK implant (PEEK-PDA-Sr/AMP) through a mussel-inspired self-assembly process, incorporating strontium ions (Sr 2+ ) for dual biological functions and the antimicrobial peptide PMAP-36. A polydopamine (PDA) coating was first applied to enhance microscale surface roughness and hydrophilicity. Subsequently, Sr 2+ and AMP were immobilized onto the PDA-modified surface. Results The resulting PEEK-PDA-Sr/AMP implants significantly promoted the adhesion and spatial organization of bone marrow mesenchymal stem cells (BMSCs) and macrophages (BMMs) in vitro. Furthermore, the modified surface facilitated macrophage polarization toward a pro-regenerative phenotype, thereby fostering an osteoimmune microenvironment conducive to osteogenic differentiation of BMSCs. The functionalized implants also exhibited strong antibacterial efficacy against both Staphylococcus aureus and Escherichia coli . In a rat model of osteomyelitis, in vivo evaluations via micro-CT, histology, and immunohistochemistry confirmed that the PEEK-PDA-Sr/AMP implants markedly enhanced immunomodulation, bone regeneration, and osseointegration. Discussion This study demonstrates a novel surface bioengineering strategy for constructing multifunctional PEEK implants with improved immunomodulatory, osteogenic, and antibacterial properties, offering a promising solution to meet complex clinical requirements in orthopedic applications.