The development of exceptional bioinks with excellent printability, high fidelity, and excellent cell viability maintenance for extrusion bioprinting remains a major challenge. Gelatin is an ideal candidate bioink due to its biocompatibility, biodegradability, and non-immunogenicity. However, its inherently low viscosity and unstable physical gelation under physiological conditions make it unsuitable for direct extrusion bioprinting of tissue-like gelatin constructs with high fidelity. Herein, sequential chemical modification using reversible quadruple-hydrogen-bonded ureido-pyrimidinone (UPy) and enzyme-responsive tyramine moieties (Tyr) were devloped to endow the gelatin with a temperature-programmable viscosity and enzyme-controlled solidification, thus realizing enhanced printability and superior fidelity. As demonstrated in a proof-of-concept study, various cell-laden constructs were built based on our modified gelatin, including two-dimensional human bone marrow mesenchyma...

中文翻译：

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基于温度可编程和可酶固化的明胶生物墨水可实现轻松的挤出生物打印。

具有卓越的可印刷性，高保真度和出色的细胞生存力以维持生物挤出的卓越生物墨水的开发仍然是主要挑战。明胶由于其生物相容性，生物降解性和非免疫原性而成为理想的生物墨水。然而，其固有的低粘度和在生理条件下不稳定的物理胶凝使其不适用于具有高保真度的组织状明胶构建体的直接挤出生物印刷。在此，通过使用可逆四氢键合的脲基-嘧啶酮（UPy）和酶反应性酪胺部分（Tyr）进行顺序化学修饰，使明胶具有可设定温度的粘度和酶控制的固化，从而实现增强的可印刷性和高保真。