Smart Biomimetic 3D Scaffolds Based on Shape Memory Polyurethane for Soft Tissue Repair

Tissue-engineered biocompatible scaffolds could mimic the extracellular matrix structure for cell adhesion and proliferation; however, patients suffer from large volume implantation. In this study, a thermal sensitive shape memory polyurethane porous 3D scaffold based on poly(ε-caprolactone) and poly(ethylene glycol adipate) was developed, utilizing the water-splitting property of aliphatic hexamethylene diisocyanate (HDI) to crosslink rigid segments during the polymerization process. The chemical structure, microstructure, and morphology, as well as mechanical strength, of the scaffolds were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), a scanning electron microscope (SEM), and tensile tests. The results show that gas foaming action caused by the release of CO₂ occurred simultaneously in the reactive process, resulting in the interconnective porous structure of the PU scaffolds with a porosity of over 70% and pore sizes from 100 μm to 800 μm. Additionally, after programming to a temporary shape, the scaffolds could recover to their initial shapes and could be programmed into various shapes according to different defects. These smart shape-changeable scaffolds with high porosity and good physio-chemical properties are a promising material for minimally invasive tissue engineering.