Surface Modification of PEEK by Zn/Mg Ion Implantation for Improved Osteogenic and Antibacterial Performance

Because its elastic modulus is closer to that of cortical bone, polyetheretherketone (PEEK) has been considered a potential alternative to titanium for dental implants. However, the biological inertness and lack of intrinsic antibacterial activity of pristine PEEK limit its osseointegration and increase the risk of peri-implant infection. In this study, Zn-, Mg-, and Zn/Mg-implanted PEEK were prepared using a metal vapor vacuum arc ion source, with untreated PEEK as the control. Surface chemical composition, ion release, roughness, and wettability were characterized, and the osteogenic responses of MG-63 cells and antibacterial activity against Staphylococcus aureus and Fusobacterium nucleatum were evaluated. Ion implantation introduced Zn and/or Mg into the near-surface region of PEEK and was accompanied by increased surface roughness and improved hydrophilicity. Mg-containing surfaces, particularly the Zn/Mg group, promoted cell spreading, proliferation, alkaline phosphatase activity, and the expression of osteogenesis-related genes, including ALP, IBSP, and BGLAP. Antibacterial activity was more evident on Zn-containing surfaces, whereas Mg alone showed only limited antibacterial effects. Although Zn alone showed stronger inhibition of Fusobacterium nucleatum, Zn/Mg co-implantation achieved a more favorable overall balance between osteogenic and antibacterial performance. Zn/Mg co-implantation improved osteogenesis-related responses while adding antibacterial activity to PEEK surfaces, suggesting its potential as a coating-free modification strategy for PEEK-based implant materials.