Water-responsive shape memory thermoplastic polyurethane scaffolds triggered at body temperature for bone defect repair

Combining selective laser sintering (SLS) and water-responsive shape memory polymers triggered at body temperature is highly promising for the accomplishment of bone defect repair with the approach of minimally invasive surgery. In this work, a porous bone scaffold of biocompatible thermoplastic polyurethane (TPU) with water-responsive shape memory properties was fabricated by SLS. According to the results, the introduced water molecules cleaved the original hydrogen bonding between the C=O and N-H groups in TPU and interacted with C=O and N-H groups via hydrogen bonding when the TPU scaffold was deformed after being pre-immersed in deionized water at 37 degrees C. When water was removed by drying, the interaction between the water molecules and TPU vanished and the hydrogen bonding between the C=O and N-H groups in TPU reformed, responsible for shape fixation, and the shape fixation ratio reached 67% when pre-immersed for 24 h. In addition, the hydrogen bonding in TPU vanished again and the interaction between the water molecules and TPU reformed when immersed in deionized water at 37 degrees C for a while, which was responsible for shape recovery, and the shape recovery ratio reached 90% when pre-immersed for 24 h. Besides, in vitro biocompatibility assays illustrated that the shape recovered scaffold could facilitate cell adhesion and stimulate cell proliferation directionally. The fabricated TPU scaffold with excellent water-responsive shape memory properties may be a desirable candidate for bone defect repair.

Automated summary

Combining selective laser sintering (SLS) with water-responsive shape memory polymers provides a promising approach to minimally invasive bone defect repair. In this study, a porous bone scaffold made of biocompatible thermoplastic polyurethane (TPU) with water-responsive shape memory properties was fabricated using SLS. The results showed that water molecules can interact with TPU, affecting the hydrogen bonding and shape fixation. In vitro experiments demonstrated that the shape-recovered scaffold promotes cell adhesion and proliferation.