Geogrid-inspired robust mineralized coating promotes vascularized osseointegration of polyetheretherketone

Polyetheretherketone (PEEK) is widely used in orthopedic implants but integrates poorly with surrounding bone. Bioactive coatings can improve this, yet most adhere weakly to PEEK's inert surface-causing delamination and inflammation. Inspired by geogrid structures used in highway pavement engineering, this study presents a novel strategy for fabricating a robust strontium (Sr)-doped hydroxyapatite coating on the PEEK surface through structural mimicry. First, a porous adhesive intermediate layer resembling geogrid architecture is created on the PEEK surface via sulfonation combined with polydopamine modification. Subsequently, the modified substrate is immersed in Sr²⁺-supplemented simulated body fluid to promote ion adsorption and induce mineralization. The resulting mineralized coating achieves strong interfacial bonding with the intermediate layer via mechanical interlocking and chemical/physical interactions, thereby substantially enhancing its stability under physiological loading conditions. Both in vitro and in vivo evaluations demonstrate that the Sr-doped mineralized coating endows PEEK with superior vascularization and osteoinductive properties. In conclusion, this study proposes an innovative and effective strategy for constructing a durable bioactive coating on PEEK surfaces, holding significant promise for advancing its clinical efficacy in orthopedic applications.