4D Printing Micelle-enhanced Shape Memory Polymer for Minimally Invasive Implant

4D-printable shape memory polymers (SMPs) hold great promise for fabricating shape morphing biomedical devices, but most existing printed polymers either require harsh activation conditions or lack sufficient mechanical strength for vascular implantation. Here, we report a dual-stimuli-responsive shape memory polymer system enhanced by acrylated Pluronic F127 (PF127-DA) micelles, which can be fabricated using digital light processing (DLP) based 3D printing. The PF127-DA based nanoscale micelles, which are formed via self-assembly in the hydrogel ink for 3D printing, act as crosslinkers to improve mechanical strength, fatigue resistance and elastic recovery. After drying the printed hydrogel, the obtained SMPs exhibit excellent shape recovery behaviour under mild physiological conditions—specifically body temperature (37 °C) and aqueous swelling—resulting in recovery stress up to about 150 kPa. This swelling-assisted actuation enables effective radial support, making the printed constructs suitable for vascular use. In vitro cytocompatibility assays with NIH/3T3 fibroblasts confirmed the suitable biocompatibility. Furthermore, the self-expanding behavior of the printed stents was validated in an occluded vessel model under physiological conditions. These results demonstrate the feasibility of 4D printed micelle-enhanced SMP for patient-specific, minimally invasive vascular stents and other soft implantable devices requiring high recovery force under physiological stimulation.