3D-Printed Polyurethane Tissue-Engineering Scaffold with Hierarchical Microcellular Foam Structure and Antibacterial Properties

This work proposes a facile fabrication strategy of polyurethane (TPU) tissue-engineering scaffold with hierarchical structure, designed by combination of the fused deposition modeling (FDM) 3D printing and supercritical microcellular foaming by carbon dioxide (CO₂). Further surface modification of TPU scaffold with graphene oxide (GO) was carried out by in situ polymerization of polydopamine (PDA) to ensure stable loading of GO with antibacterial properties. The influence of 3D-printing temperature and speed on the microcellular cell morphology of TPU scaffold was investigated and optimized. The microcellular foaming and expansion process was indicated to compensate mechanical loss because of the gaps of stacking layers by FDM printing, and the reported tensile strength of 28 MPa matched well with that of natural cartilage tissue constructs. More interesting, the formation of interconnected open pores on the surface of foamed TPU scaffold shows much more enhanced cell adhesion because of the bigger specific surface area of microcellular structure. Similarly, the foamed TPU scaffold exhibits good absorption of GO nanosheets by the synthesized PDA on the surface and antibacterial properties, compared with the unfoamed TPU scaffold. This work offers a strategy for designing and manufacturing polymer tissue-engineering scaffold with hierarchical structure and good antibacterial property.