Three-Dimensional\nPrinting of Biodegradable Piperazine-Based Polyurethane-Urea Scaffolds\nwith Enhanced Osteogenesis for Bone Regeneration

Abstract

Synthetic\nbiodegradable polymeric scaffolds with uniformly interconnected pore\nstructure, appropriate mechanical properties, excellent biocompatibility,\nand even enhanced osteogenesis ability are urgently required for in\nsitu bone regeneration. In this study, for the first time, a series\nof biodegradable piperazine (PP)-based polyurethane-urea (P-PUU) scaffolds\nwith a gradient of PP contents were developed by air-driven extrusion\n3D printing technology. The P-PUU ink of 60 wt % concentration was\ndemonstrated to have appropriate viscosity for scaffold fabrication.\nThe 3D-printed P-PUU scaffolds exhibited an interconnected porous\nstructure of about 450 μm in macropore size and about 75% in\nporosity. By regulating the contents of PP in P-PUU scaffolds, their\nmechanical properties could be moderated, and P-PUU1.4 scaffolds with\nthe highest PP contents exhibited the highest compressive modulus\n(155.9 ± 5.7 MPa) and strength (14.8 ± 1.1 MPa). Moreover,\nboth in vitro and in vivo biological results suggested that the 3D-printed\nP-PUU scaffolds possessed excellent biocompatibility and osteoconductivity\nto facilitate new bone formation. The small molecular PP itself was\nconfirmed for the first time to regulate osteogenesis of osteoblasts\nin a dose-dependent manner and the optimum concentration for osteoconductivity\nwas about ∼0.5 mM, which suggests that PP molecules, together\nwith the mechanical behavior, nitrogen-contents, and hydrophilicity\nof P-PUUs, play an important role in enhancing the osteoconductive\nability of P-PUU scaffolds. Therefore, the 3D-printed P-PUU scaffolds,\nwith suitable interconnected pore structure, appropriate mechanical\nproperties, and intrinsically osteoconductive ability, should provide\na promising alternative for bone regeneration.