Novel Hybrid Biocomposites for Tendon Grafts: The Addition of Silk to Polydioxanone and Poly(lactide-co-caprolactone) Enhances Material Properties, In Vitro and In Vivo Biocompatibility

This study developed hybrid biocomposite materials intended for tendon/ligament grafts by blending poly(p-dioxanone) (PDO) and poly(lactide-co-caprolactone) (LCL) with 1–15% silk. The authors characterized morphology (SEM/EDS), thermal behavior (DSC), surface properties (AFM/contact angle), and degradation (PBS hydrolysis and protease-based conditions), and assessed biocompatibility using tendon-derived stem cells (in vitro) and a murine subcutaneous implantation model (in vivo). Mechanically, adding low silk content (notably ~3–5%) improved miscibility of PDO/LCL phases, tuned stiffness/ductility, and produced favorable toughness while avoiding high-content silk agglomeration that reduced performance. The team also extruded fibers and braided prototype grafts, showing tensile properties in the range reported for human ACL benchmarks, supporting feasibility for ligament repair applications.