4D Printed Shape Memory Polyurethane-Based Composite for Bionic Cartilage Scaffolds

Repair of articular cartilage defects is a major challenge in orthopedic surgery due to the deficient self-regeneration capability. Cartilage tissue engineering scaffolds provide a promising approach to cartilage defect repair. Proper mechanical properties, interconnected internal structure, customized shape, and minimally invasive treatment are urgent requirements for a qualified cartilage scaffold. Here, a shape memory composite used for cartilage defects is prepared by adding nanohydroxyapatite into a shape memory polyurethane matrix, exhibiting good mechanical properties and biocompatibility. Based on its rheological properties, the composite melt can be printed into 4D printed structures with high precision and quality in a simple and clean way. Inspired by the structure of mangroves, a bionic 4D printed cartilage scaffold is designed and manufactured, presenting a good shape memory performance at a temperature close to body temperature. The 4D printed cartilage scaffold can expand from a conveniently insertional shape to a deployed shape to match defect, providing a novel idea for the personalized and minimally invasive treatment of cartilage defects.