Bioinspired Collagen-Zn-PEEK Mixed Interfacial Layer on Color-Stable, Surface-Hardened PEEK for Enhanced Osseointegration

Abstract Although polyetheretherketone (PEEK) offers mechanical advantages over titanium, its clinical utility is often hampered by poor bioactivity and insufficient surface hardness. Drawing inspiration from the natural bone microenvironment, we report a dual-functionalization strategy combining plasma immersion ion implantation (PIII) and covalent collagen grafting to bridge the gap between PEEK and host bone tissue. Among the diverse ion sources tested (Cu, Zn, N2, TiSi), the zinc-incorporated and collagen-modified sample (C-Zn-PEEK) emerged as the superior candidate, which forms a special mixed interfacial layer at the surface. It not only synergistically improved surface hardness and biological functions—including potent antibacterial and pro-osteogenic activities—but also uniquely maintained the inherent aesthetic color of PEEK, a critical factor for patient-facing dental and orthopedic applications. In vivo results further validated that the C-Zn-PEEK significantly promoted osseointegration and bone–implant contact. This bioinspired, color-stable engineering approach provides a robust platform for the next generation of high-performance, aesthetically favorable PEEK implants.