Biodegradable Polyurethane Scaffolds with Hard and Soft Compartments for Potential Bone-to-tendon Regeneration

Poly(ε-caprolactone) (PCL)-based polyurethane (PU) scaffolds with hard and soft compartments at either end were fabricated by fused deposition modeling (FDM) technique for potential bone-to-tendon regeneration. Waterborne-PU (WBPU) dispersions with different ratios of diisocyanate and PCL diol were synthesized to control the tensile properties suitable for either compartment at the end of the WBPU/PCL scaffolds. The three-dimensionally (3D) printed WBPU/PCL scaffold with two compartments was ionically cross-linked by calcium chloride, while the hard compartment of the scaffolds was further decorated by hydroxyapatite (HAp) using an alternative soaking method. In vitro tests revealed the higher proliferation rate and alkaline phosphatase (ALP) activity of osteoblastic cells (MC3T3-E1) on the hard compartment of the scaffold. Meanwhile, myocytes (C2C12) proliferated well on the soft compartment. We believe that the 3D printed WBPU/PCL scaffolds with controlled porous structure and mechanical property have wide potential applications for bone-to-ligament and bone-to-cartilage, as well as bone-to-tendon.