Programmable 4D Printing of Photoactive Shape Memory Composite Structures.

4D printing is an advanced manufacturing technology combining additive manufacturing with smart materials. Based on light-active shape memory composites, smart medical structures with remote control capability, therapeutic function, and biocompatibility are hopefully fabricated by 4D printing. Here, a multifunctional composite with good mechanical properties, biocompatibility, and light-active shape memory performance is prepared by incorporating gold nanoparticles into a shape memory polyurethane matrix. The composites demonstrate a rapid and stable light-thermal effect, which can achieve localized and controlled breast tumor ablation, providing an approach to hyperthermia treatment for cancer cells. By directly bioprinting the composite melt, a series of 4D-printed structures are manufactured accurately in a convenient, clean, and safe way, which show a fast autonomous light-driven shape recovery process. The examples of a 4D-printed soft tissue scaffold and intraluminal scaffold can expand from a conveniently insertional shape to an expanded shape under light exposure. The proposed strategies provide great inspiration for customized multifunctional light-thermal therapeutic structures for minimally invasive treatment.