Morphology and Function Dual‐Adjustable Biomimetic 4D‐Printed Scaffold for the Regenerative Restoration of Complex Bone Defects

Abstract 4D‐printing offers great potentials for fabricating scaffolds with dynamic shapes and functions, which are desirable for the repair of complex bone defects (such as those in oral and maxillofacial region). However, most current 4D‐printed scaffolds are far from ideal for clinical applications due to their unsuitable deformation conditions, inherent hydrophobicity, and lack of bone regenerative function. The design of a morphology and function dual‐adjustable 4D‐printed scaffold with biomimetic “hard‐soft” compositions is proposed. The “hard” 4D‐printed framework, fabricated from the composite of poly (l‐lactide‐co‐trimethylene carbonate) (PLMC) and nano‐hydroxyapatite (nHA) via extrusion‐based 3D printing, is demonstrated to possess suitable transition temperature (T _trans ) slightly above the physiological level, along with favorable mechanical and shape memory properties. Furthermore, the “soft” hydrogel layer containing nHA@polydopamine (PDA) nanoparticles loaded with pargyline (PGL) (nHA@PDA‐PGL) is integrated with the framework to enhance hydrophilicity and cytocompatibility, as well as to offer near‐infrared (NIR) light‐responsive photothermal effect and sustained release of PGL to promote osteogenesis. This composite system exhibited unique NIR light‐triggered shape recovery capability, morphological adaptation to the defects, along with significantly improved bone regeneration efficacy. Overall, these findings underscore the remarkable potential of the present 4D‐printed scaffold for the regenerative restoration of complex bone defects.