Polydopamine-immobilized actively mineralizing matrix vesicles on titanium implants for enhanced osseointegration.

To address the limited bioactivity of titanium implant surfaces, particularly under compromised bone-healing conditions, this study developed a biofunctionalization strategy by constructing an OST-MVs@P-Ti system, in which osteoblast-derived matrix vesicles (OST-MVs), with inherent mineralization capability, were stably immobilized on titanium via a polydopamine (PDA) coating. This design mimics the natural bone mineralization mechanism, utilizing OST-MVs not only as bioactive signal carriers but also as direct executors of hydroxyapatite formation. The resulting surface exhibited enhanced hydrophilicity and roughness, good biocompatibility, and significantly promoted the adhesion, migration, and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) in vitro, as evidenced by upregulated Alkaline Phosphatase (ALP) activity, mineral deposition, and osteogenic gene/protein expression. In a rat femoral model, the OST-MVs@P-Ti implant demonstrated enhanced osseointegration with increased bone volume and intimate bone-implant contact. This study provides a biomimetic "actively mineralizing" surface modification strategy for dental and orthopedic implants and offers a promising platform for improving osseointegration.