4D printed hydrogels are 3D printed objects whose properties and functions are programmable. In the definition of 4D printing, the fourth dimension arises from the ability of printed structures to change their shape and/or function over time when exposed to given conditions environmental stimuli, during their post-press life. Stimulation-responsive hydrogels produced by the emerging 4D bioprinting technology are currently considered as encouraging tools for various biomedical applications due to their exciting properties such as stretchability, biocompatibility, ultra-flexibility, and printability. Using 3D printing technology, customized functional structures with controllable geometry and trigger ability can be autonomously printed onto desired biological interfaces without considering microfabrication techniques. In this review, by studying the progress in the field of hydrogels for biointerfaces, we summarized the techniques of 4D printing gels, the classification of bioinks, the design strategies of actuators. In addition, we also introduced the applications of 4D hydrogels in tissue repair, vascular grafts, drug delivery, and wearable sensors. Comprehensive insights into the constraints, critical requirements for 4D bioprinting including the biocompatibility of materials, precise designs for meticulous transformations, and individual variability in biological interfaces.

4D 打印水凝胶是 3D 打印的物体，其属性和功能是可编程的。在 4D 打印的定义中，第四维源自打印结构在印后寿命期间暴露于给定条件环境刺激下时随时间改变其形状和/或功能的能力。由新兴的 4D 生物打印技术生产的刺激响应水凝胶目前被认为是各种生物医学应用的令人鼓舞的工具，因为它们具有令人兴奋的特性，如拉伸性、生物相容性、超柔韧性和可打印性。使用3D打印技术，具有可控几何形状和触发能力的定制功能结构可以自主打印到所需的生物界面上，而无需考虑微加工技术。在这篇评论中，通过研究生物界面水凝胶领域的进展，我们总结了4D打印凝胶技术、生物墨水的分类、执行器的设计策略。此外，我们还介绍了4D水凝胶在组织修复、血管移植、药物输送、可穿戴传感器等方面的应用。全面了解 4D 生物打印的限制条件和关键要求，包括材料的生物相容性、精细转化的精确设计以及生物界面的个体差异。和可穿戴传感器。全面了解 4D 生物打印的限制条件和关键要求，包括材料的生物相容性、精细转化的精确设计以及生物界面的个体差异。和可穿戴传感器。全面了解 4D 生物打印的限制条件和关键要求，包括材料的生物相容性、精细转化的精确设计以及生物界面的个体差异。