Biological gradients profoundly influence many cellular activities, such as adhesion, migration, and differentiation, which are the key to biological processes, such as inflammation, remodeling, and tissue regeneration. Thus, engineered structures containing bioinspired gradients can not only support a better understanding of these phenomena, but also guide and improve the current limits of regenerative medicine. In this review, we outline the challenges behind the engineering of devices containing chemical-physical and biomolecular gradients, classifying them according to gradient-making methods and the finalities of the systems. Different manufacturing processes can generate gradients in either in-vitro systems or scaffolds, which are suitable tools for the study of cellular behavior and for regenerative medicine; within these, rapid prototyping techniques may have a huge impact on the controlled production of gradients. The parallel need to develop characterization techniques is addressed, underlining advantages and weaknesses in the analysis of both chemical and physical gradients.

中文翻译：

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工程生物梯度

生物梯度深刻影响许多细胞活动，如粘附、迁移和分化，这些活动是炎症、重塑和组织再生等生物过程的关键。因此，包含仿生梯度的工程结构不仅可以支持更好地理解这些现象，还可以指导和改进再生医学的当前极限。在这篇综述中，我们概述了包含化学物理和生物分子梯度的设备工程背后的挑战，根据梯度制造方法和系统的最终性对它们进行分类。不同的制造工艺可以在体外系统或支架中产生梯度，这是研究细胞行为和再生医学的合适工具；其中，快速原型技术可能对梯度的受控生产产生巨大影响。解决了开发表征技术的并行需求，强调了化学和物理梯度分析的优缺点。