Fabrication of an Asymmetric PCL-HAP/CS Bilayer Composite Membrane with Dual Osteogenic and Fibrogenic Functions for Guided Bone Regeneration

This study develops a PCL-HAP/CS bilayer membrane to address limitations in current bone regeneration materials. Traditional single-component materials often exhibit poor biocompatibility, mechanical mismatch, and insufficient osteogenic capacity. To overcome these issues, a composite structure was engineered by combining hydroxyapatite (HAP) synthesized via co-precipitation and silane-treated for enhanced compatibility, polycaprolactone (PCL) for mechanical strength, and chitosan (CS) for bioactivity. The bilayer design features a PCL-HAP layer fused with a CS layer, mimicking natural bone’s stratified architecture. Material characterization confirmed the composite’s structural integrity and functional properties. In vitro tests demonstrated selective cell compatibility: osteoblasts thrived on the mineral-rich PCL-HAP side, while fibroblasts showed enhanced adhesion on the CS layer. Rat skull defect experiments revealed dual functionality—the membrane provided mechanical support for bone regeneration while delivering antibacterial effects to surrounding soft tissues. The synergistic combination leverages PCL’s durability, HAP’s osteoinduction, and CS’s antimicrobial properties, effectively compensating for individual material weaknesses. This asymmetric membrane design shows significant potential for clinical bone repair applications, particularly in oral surgery, by simultaneously addressing hard tissue regeneration and soft tissue protection requirements.