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

Abstract

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 CO and N–H groups in TPU and interacted with CO and N–H groups via hydrogen bonding when the TPU scaffold was deformed after being pre-immersed in deionized water at 37 °C. When water was removed by drying, the interaction between the water molecules and TPU vanished and the hydrogen bonding between the CO 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 °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.