Jincai Yin,Delin Zhang,Zihan Xu,Wenxin Fan,Yanzhi Xia,Kunyan Sui
Self-shaping hydrogel actuators have promising applications in various fields. However, one hydrogel actuator can generally access only one specifically predefined deformation and output force, which are determined by its thermodynamic equilibrium swelling state under external stimuli. Here, we present a simple yet versatile strategy for precisely programming the output force/energy of dual-gradient hydrogel actuators. The strategy is based on thermodynamic nonequilibrium snapping deformations occurring during the recovery process of predeformed dual-gradient hydrogel actuators in low-temperature water. The output force/energy of such thermodynamic nonequilibrium snapping deformation is highly associated with predeformation conditions of the hydrogel actuators, which increases with the increase of the predeformation temperature or time. In consequence, just by adjusting the predeformation conditions of the dual-gradient hydrogel actuators, their output force, energy, and power can be modulated precisely and continuously during the snapping deformation. The as-prepared hydrogel actuators can not only be used as smart lifters and grippers with ultrahigh accuracy of weight identification but also act as smart switches in the timing circuits with precisely adjustable operating time, paving the way for the design of a new generation of actuation materials.
Neurological function recovery after peripheral nerve injury (PNI) is exceptionally challenging, chiefly because neurons cannot efficiently proliferate, differentiate, and form regenerated axons to pass through the defect region expeditiously and transmit neurological signals. In this study, a four-dimensional (4D) oriented dynamic scaffold is constructed based on shape memory polymer (SMP), which can regulate spatiotemporally controllable neuronal early adequate proliferation, subsequently effective differentiation and axon formation by synergizing the on-demand microtopography and deformation force-based mechanical stimuli (DFMS). This dynamic scaffold can accelerate the restoration of large segmental nerve defects, elevate the neural signaling efficiency by 60% compared with static scaffold, and finally form the functionalized robust regenerating nerve fascicles with comparable therapeutic effects on autologous nerve transplantation. Furthermore, the crucial role of Piezo1/Camk2b modulated neuronal differentiation and axon extension is also revealed through deep transcriptomic analysis. In summary, the 4D oriented dynamic scaffold can precisely and remotely regulate neuronal behavior and fate in a non-invasive way, which has excellent potential for clinical application in peripheral nerve restoration.
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