Cartilage-Inspired Bilayer Composite Hydrogel for Enhanced Load-Bearing and Lubrication in Articular Cartilage Repair

Articular cartilage is a natural tissue characterized by a distinct layered structure, in which the synergistic interaction of its composite architecture provides exceptional low friction and excellent load-bearing capacity. In this study, inspired by the layered structure and hydration-based lubrication mechanism of articular cartilage, we developed a bilayer composite hydrogel using a UV-triggered surface catalytic-initiated radical polymerization (UV-SCIRP) approach. A hydrophilic polyelectrolyte boundary layer, providing effective lubrication, was polymerized onto the surface of the underlying tough hydrogel via a redox initiation system. The resulting bilayer hydrogel effectively integrates low surface friction with high load-bearing capacity in the underlying layer. This cartilage-inspired bilayer design presents a promising strategy for developing bioinspired materials that mimic the mechanical and tribological properties of native articular cartilage.