4D printing has shown great promise in a variety of biomedical applications owing to the adaptability and minimally invasive implantation of fabricated devices. However, commonly used 3D printing of biocompatible shape memory polymers (SMPs) results in structures with low printing resolution, a lack of proper mechanical properties (relative low toughness), and undesirable transition temperatures (T_trans), all of which cause complications during implantation operations. Herein, we demonstrate 4D printing of biocompatible SMP poly(glycerol dodecanoate) acrylate (PGDA) and Acrylic Acid (AA) with a T_transin a range of human body temperature (~37°C), making it appropriate for shape programming at the room temperature and then shape transformation within the human body. In addition, the resin used as the ink for Digital Light Processing (DLP) 3D printing possesses suitable rheological properties to allow for the fabrication of a variety of high-resolution complex 3D structures such as "boat," "diamond," and "human hand," with the printing speed of 25-100 mm/h. The printed 3D structures show shape memory properties, including a large fixity ratio of 98% at 20°C and a significant recovery ratio of 100% at 37°C. Moreover, Young's moduli (40-170 MPa) and toughness (10-20 MJ/m³) of the printed structures can be decreased by 90 and 25 times, respectively, due to the phase transition of PGDA. Furthermore, cell studies showed cell viability of over 90% and attachment and proliferation of cells over the printed materials. Finally, Abdominal Aneurysm and Left Atrial Appendage were chosen as the target diseases. Devices were designed and printed for defects scanned from animal models and tested both in vitro and in vivo. The implantation of personalized devices demonstrated the printed constructs' geometrical and mechanical adaptability. This newly developed PGDA-AA SMP-based 4D printing technology may pave the way for the fabrication of shape memory scaffolds for personalized biomedical applications.

Scheme showing the workflow of scanning the animal model, personalized 4D printing, and Implantation of the shape-memory device.

Jian Lin

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