4D printing of a multi-transitioning shape memory polymer with a recovery onset towards precision endovascular...

Practical use of shape memory polymers (SMPs) in endovascular embolization is often limited by their reliance on external triggers not easily applicable within the vascular environment. Addressing this, we introduce digital light 4D printing of an SMP that leverages naturally occurring physiological stimuli (body temperature and hydration) to initiate shape transformations. This SMP, termed PGDA-PUA-PAA, is photo-crosslinked from a resin consisting of poly(glycerol dodecanoate acrylate) (PGDA) oligomer, 10-undecenoic acid (UA), and acrylic acid (AA) monomers. It features dual-transition temperatures of ∼20 °C and ∼40 °C for distinct, programmable shape changes: one at ambient conditions and the other at physiological conditions. Importantly, it shows a controlled shape recovery onset at the second transition. The onset duration at 37 °C in a hydrated environment can be programmed by controlling ink composition and crosslinking density. During recovery onset, the SMP hydrates to trigger the second transition to its original shape. After full hydration, the material transforms into a hydrogel with a volume expansion of ∼22× (the third shape change). Elasticity of the hydrogel is preserved by self-assembled phase domains induced by water, as revealed by spatiotemporal Fourier Transform Infrared (FTIR) spectroscopy mapping. Enabled by high-resolution digital light 4D printing, this PGDA-PUA-PAA shape memory polymer, which exhibits multiple shape transitions, strong mechanical integrity, and cytocompatibility, achieved precise occlusion in both in vitro vascular models and a nonsurvival in vivo femoral artery embolization model. These results demonstrate a new class of physiologically triggered, catheter-deployable materials that can potentially enable minimally invasive and precision endovascular applications. STATEMENT OF SIGNIFICANCE: Precise vascular occlusion remains a major challenge in endovascular embolization, where current metallic and polymeric embolic devices often suffer from limited conformability, poor deployment control, and risks of incomplete occlusion. Here, we introduce a four-dimensional (4D) printed, physiologically triggered shape memory polymer (SMP) that integrates dual transition temperatures with a programmable recovery onset, enabling controlled activation in response to body temperature and hydration. Unlike conventional thermally triggered SMPs, this material remains stable during catheter delivery and recovers only under physiological conditions, ensuring site-specific deployment. Upon hydration, it transforms into a tough, elastic hydrogel with >20-fold volume expansion, enabling dense vessel packing and sustained occlusion. This work demonstrates a catheter-deployable, hydration-responsive 4D-printed embolic material platform and establishes its feasibility through in vitro studies and a nonsurvival in vivo proof-of-concept model.