As a ubiquitous feature of the biological world, gradation, in either composition or structure, is essential to many functions and processes. Taking protein gradation as an example, it plays a pivotal role in the development and evolution of human bodies, including stimulation and direction of the outgrowth of peripheral nerves in a developing fetus. It is also critically involved in wound healing by attracting and guiding immune cells to the site of injury or infection. Another good example can be found in the tendon-to-bone enthesis that relies on gradations in composition, structure, and cell phenotype to create a gradual change in mechanical stiffness. It is these unique gradations that eliminate the high level of stress at the interface, enabling the effective transfer of mechanical load from tendon to bone. How to fabricate and utilize graded surfaces and materials has been a constant theme of research in the context of materials science, chemistry, cell biology, and biomedical engineering. In cell biology, for example, graded surfaces are employed to investigate the fundamental mechanisms related to embryo development and to elucidate cell behaviors under chemo-, hapto-, or mechano-taxis. Scaffolds based upon graded materials have also been widely explored to enhance tissue repair or regeneration by accelerating cell migration and/or controlling stem cell differentiation.

中文翻译：

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用于生物和生物医学应用的功能分级表面的合理制造


作为生物界无处不在的特征，无论是组成还是结构，渐变对于许多功能和过程都是必不可少的。以蛋白质分级为例，它在人体的发育和进化中起着关键作用，包括刺激和指导发育中的胎儿周围神经的生长。它还通过吸引和引导免疫细胞到损伤或感染部位，与伤口愈合密切相关。另一个很好的例子是肌腱到骨骼的附着点，它依靠成分、结构和细胞表型的渐变来产生机械刚度的逐渐变化。正是这些独特的渐变消除了界面处的高水平应力，从而能够有效地将机械负荷从肌腱传递到骨骼。在材料科学、化学、细胞生物学和生物医学工程的背景下，如何制造和利用渐变表面和材料一直是研究的永恒主题。例如，在细胞生物学中，分级表面被用来研究与胚胎发育相关的基本机制，并阐明化疗、触碰或机械趋向下的细胞行为。基于分级材料的支架也被广泛探索，通过加速细胞迁移和/或控制干细胞分化来增强组织修复或再生。