Shape-Morphing Tissue Engineering Scaffolds Based on Hydro-thermal Responsive Polymers

Shape-morphing tissue engineering scaffolds attract increasing attention as they can meet the demanding requirements of some clinical applications and adapt to local body environments. 4D printing is a suitable tool for fabricating such scaffolds with the use of shape memory polymers (SMP). But most SMPs can only respond to a single stimulus, while the human body can provide multiple stimuli. Blending a synthetic SMP with a biocompatible natural hydrogel that can respond to other stimuli can produce a material with good shape memory capability and desirable biological properties. In this study, poly(D,L-lactide-co-trimethylene carbonate) (PDLLA-co-TMC)/gelatin methacryloyl (GelMA) blends were made and 4D printed into scaffolds that have desired properties and can respond to hydro-thermal dual stimuli. The morphology, chemical composition, structure and mechanical properties of fabricated scaffolds were investigated. Their shape morphing behaviour was studied at 37 ? in air and in water. PDLLA-co-TMC/GelMA blend scaffolds showed good biocompatibility and much improved mechanical properties. In vitro degradation of PDLLA-co-TMC/GelMA scaffolds was significantly faster. For dynamic shape changes from flat to circular shape, they could respond to hydro-stimulus, which was achieved via depth-changing UV irradiation of scaffolds, and thermal-stimulus due to PDLLA-co-TMC. These shape-morphing scaffolds have the potential for regenerating tubular tissues such as blood vessels.