PCL/Chitosan/Bioglass Hybrid Composite Shape Memory Scaffolds With Accelerated Degradation and Enhanced Bioactivity

"Self-fitting" shape memory polymer (SMP) scaffolds based on cross-linked poly(ε-caprolactone)-diacrylate (PCL-DA) represent a promising regenerative strategy for treating irregular craniomaxillofacial bone defects. Beyond conformal fitting, such scaffolds should exhibit intrinsic bioactivity as well as controlled and robust degradation rates. In prior reports, chitosan (CS) and 45S5 Bioglass (BG) were separately incorporated to form SMP scaffolds. "CS-only" hybrid scaffolds suppressed fungal biofilm formation and accelerated degradation, whereas "BG-only" composite scaffolds induced hydroxyapatite (HAp) mineralization and also accelerated degradation. Herein, "hybrid composite" scaffolds incorporating both CS and BG were developed. Semi-interpenetrating networks were fabricated using PCL-DA and CS-graft-PCL at 90:10 and 75:25 wt% ratios, corresponding to 1 and 2.5 wt% CS, respectively. BG was introduced at 5 and 10 wt%, and localized on the pore walls. These scaffolds retained excellent shape memory behavior despite a reduction in PCL crystallinity. Degradation was faster versus corresponding BG-only and CS-only scaffolds, and robust HAp mineralization was observed after just 1 day in 1X simulated body fluid. The hybrid composite scaffolds were mechanically robust, and HAp mineralization induced a substantial increase in modulus.