The 11th Global Conference on Polymer and Composite Materials (PCM 2024)

Abstract: Degradable biomaterials have emerged as a viable alternative to permanent materials for regenerative bone medicine. Although Polycaprolactone (PCL) exhibits remarkable extensibility and toughness, its low elastic modulus and strength, hydrophobicity, and excessively slow degradation rate limit its application in orthopedics. Natural silk fibers with macroscopic continuity and highly ordered morphology are selected to reinforce PCL to satisfy the mechanical and biological requirements for bone grafts. In this talk, we discuss the design, fabrication, and bone graft application of fiber silk-PCL biocomposites.
Silk-PCL composites with 20%/40%/60% silk were fabricated via layer-by-layer assembly and hotpressing, allowing facile incorporation of drugs. The fiber silk composites exhibited compatible modulus (1GPa) to the majority of bone tissues, high compressive strength (150MPa), high toughness, hydrophilicity, and water adsorption behavior. The 6-month in vitro degradation experiment showed that passive surface erosion and bulk hydrolysis of the silk-PCL composite by the aqueous environment is negligible, and the fiber-matrix interfaces remained robust. In the in vivo rat subcutaneous model, the degradation of silk composites is significantly accelerated via inflammatory cells mediated PCL dissolution from the surface. Fiber silks are proposed to modulate the inflammatory responses toward synchronized material degradation and tissue reconstruction. A rabbit tibial defect model shows a strong tissue-composite implant bonding, suggesting sufficient mechanical function and the regeneration of new bone.
The silk-PCL composites bring forward exceptional comprehensive mechanical performance and desirable degradation behavior in vivo through the coupled inflammatory modulation effects of silk and PCL. This work may herald the advent of a novel biomaterial for load-bearing bone repair.