Gelatin Methacryloyl (GelMA) is one of the most used biomaterials for a wide range of applications, such as drug delivery, disease modeling and tissue regeneration. GelMA is obtained from gelatin, which can be derived from different sources (e.g., bovine skin, and porcine skin), through substitution of reactive amine and hydroxyl groups with methacrylic anhydride (MAA). The degree of functionalization (DoF) can be tuned by varying the MAA amount used; thus, different protocols, with different reaction efficiency, have been developed, using various alkaline buffers (e.g., phosphate-buffered saline, DPBS, or carbonate-bicarbonate solution). Obviously, DoF modulation has an impact on the final GelMA properties, so a deep investigation on the features of the obtained hydrogel must be carried on. The purpose of this study is to investigate how different gelatin sources and synthesis methods affect GelMA properties, as literature lacks direct and systematic comparisons between these parameters, especially between synthesis methods. The final aim is to facilitate the choice of the source or synthesis method according to the needs of the desired application. Hence, chemical and physical properties of GelMA formulations were assessed, determining the DoFs, mechanical and viscoelastic properties by rheological analysis, water absorption by swelling capacity and enzymatic degradation rates. Biological tests with lung adenocarcinoma cells (A549) were performed. Moreover, since 3D bioprinting is a rapidly evolving technology thanks to the possibility of precise deposition of cell-laden biomaterials (bioinks) to mimic the 3D structures of several tissues, the potential of different GelMA formulations as bioinks have been tested with a multi-material approach, revealing its printability and versatility in various applications.

中文翻译：

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3D 多材料生物打印的 GelMA 合成和来源比较

甲基丙烯酰明胶 (GelMA) 是最常用的生物材料之一，具有广泛的应用，例如药物输送、疾病建模和组织再生。 GelMA 是通过用甲基丙烯酸酐 (MAA) 取代活性胺和羟基而从明胶中获得的，明胶可以衍生自不同的来源（例如牛皮和猪皮）。功能化程度 (DoF) 可以通过改变 MAA 的用量来调整；因此，已经开发出具有不同反应效率的不同方案，使用各种碱性缓冲液（例如磷酸盐缓冲盐水、DPBS或碳酸盐-碳酸氢盐溶液）。显然，DoF调制对最终的GelMA性能有影响，因此必须对所得水凝胶的特性进行深入研究。本研究的目的是研究不同的明胶来源和合成方法如何影响 GelMA 特性，因为文献缺乏这些参数之间的直接和系统的比较，特别是合成方法之间的比较。最终目标是促进根据所需应用的需要选择来源或合成方法。因此，评估了 GelMA 制剂的化学和物理特性，通过流变分析确定自由度、机械和粘弹性特性、通过溶胀能力确定吸水率和酶降解率。对肺腺癌细胞（A549）进行了生物学测试。此外，由于 3D 生物打印是一项快速发展的技术，由于可以精确沉积充满细胞的生物材料（生物墨水）来模拟多种组织的 3D 结构，因此不同的 GelMA 配方作为生物墨水的潜力已经通过多种材料进行了测试。方法，揭示其可印刷性和在各种应用中的多功能性。