Nowadays, bioprinting is rapidly evolving and hydrogels are a key component for its success. In this sense, synthesis of hydrogels, as well as bioprinting process, and cross-linking of bioinks represent different challenges for the scientific community. A set of unified criteria and a common framework are missing, so multidisciplinary research teams might not efficiently share the advances and limitations of bioprinting. Although multiple combinations of materials and proportions have been used for several applications, it is still unclear the relationship between good printability of hydrogels and better medical/clinical behavior of bioprinted structures. For this reason, a PRISMA methodology was conducted in this review. Thus, 1,774 papers were retrieved from PUBMED, WOS, and SCOPUS databases. After selection, 118 papers were analyzed to extract information about materials, hydrogel synthesis, bioprinting process, and tests performed on bioprinted structures. The aim of this systematic review is to analyze materials used and their influence on the bioprinting parameters that ultimately generate tridimensional structures. Furthermore, a comparison of mechanical and cellular behavior of those bioprinted structures is presented. Finally, some conclusions and recommendations are exposed to improve reproducibility and facilitate a fair comparison of results.

中文翻译：

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用于生物打印的水凝胶：水凝胶合成、生物打印参数和生物打印结构行为的系统综述

如今，生物打印正在迅速发展，水凝胶是其成功的关键组成部分。从这个意义上说，水凝胶的合成、生物打印过程和生物墨水的交联对科学界来说是不同的挑战。缺少一套统一的标准和通用框架，因此多学科研究团队可能无法有效地分享生物打印的进步和局限性。尽管材料和比例的多种组合已用于多种应用，但仍不清楚水凝胶良好的可打印性与生物打印结构更好的医学/临床行为之间的关系。因此，本次审查采用了 PRISMA 方法。因此，从 PUBMED、WOS 和 SCOPUS 数据库中检索到了 1,774 篇论文。经过筛选后，我们对 118 篇论文进行了分析，以提取有关材料、水凝胶合成、生物打印过程以及生物打印结构测试的信息。本系统综述的目的是分析所使用的材料及其对最终生成三维结构的生物打印参数的影响。此外，还对这些生物打印结构的机械和细胞行为进行了比较。最后，提出一些结论和建议，以提高可重复性并促进结果的公平比较。