Nanoassembly-Engineered Enzyme-Armored Bone Implants Mediating Confinement Biocatalysis, Biomimetic Mineralization, and Self-Disinfection

Orthopedic polyetheretherketone (PEEK) exhibits a favorable bone-matching modulus yet suffers from severely compromised osseointegration due to its bioinert surface that is incapable of inducing mineralization, a critical deficit particularly detrimental in aging populations with diminishing osteoregenerative capacity. Enzymatic mineralization strategies inspired by natural bone development offer a potent solution, but conventional systems face irreconcilable activity–stability trade-offs, while mineralized interfaces inadvertently elevate infection risks. To resolve these constraints, we engineered hierarchically confined “armored enzyme” microreactors simultaneously encapsulating and covalently immobilizing alkaline phosphatase (ALP, a key calcification regulator) within a zinc imidazolate framework (ZIF-90) exoskeleton, which were integrated into a biomimetic silk fibroin (SF) matrix and anchored onto catechol/aldehyde-modified PEEK substrates via interfacial self-assembly. The dual stabilization mechanism, alongside the shelter effect of ZIF-90 and unique β-sheet domain protection of SF, effectively preserved ALP enzymatic activity within the assemblies under thermal stress (up to 50 °C) and through 10 operational cycles. Furthermore, this biocatalytic platform mediated efficient Ca2+ and PO43– liberation from calcium glycerophosphate hydrolysis, fostering biomimetic apatite formation on SF mineralization templates within 3 days. Moreover, the functionalization elicited ameliorative surface wettability and osteoblastic adhesion and metabolic/osteogenic activity while affording self-antibacterial defense through acid-triggered zinc release. This work establishes a rational enzymatic engineering approach for multifunctional self-mineralizing orthopedic implants.