With the increasing growth of the algae industry and the development of algae biorefinery, there is a growing need for high-value applications of algae-extracted biopolymers. The utilization of such biopolymers in the biomedical field can be considered as one of the most attractive applications but is challenging to implement. Historically, polysaccharides extracted from seaweed have been used for a long time in biomedical research, for example, agarose gels for electrophoresis and bacterial culture. To overcome the current challenges in polysaccharides and help further the development of high-added-value applications, an overview of the entire polysaccharide journey from seaweed to biomedical applications is needed. This encompasses algae culture, extraction, chemistry, characterization, processing, and an understanding of the interactions of soft matter with living organisms. In this review, we present algae polysaccharides that intrinsically form hydrogels: alginate, carrageenan, ulvan, starch, agarose, porphyran, and (nano)cellulose and classify these by their gelation mechanisms. The focus of this review further lays on the culture and extraction strategies to obtain pure polysaccharides, their structure-properties relationships, the current advances in chemical backbone modifications, and how these modifications can be used to tune the polysaccharide properties. The available techniques to characterize each organization scale of a polysaccharide hydrogel are presented, and the impact on their interactions with biological systems is discussed. Finally, a perspective of the anticipated development of the whole field and how the further utilization of hydrogel-forming polysaccharides extracted from algae can revolutionize the current algae industry are suggested.

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形成水凝胶的藻类多糖：从海藻到生物医学应用

随着藻类产业的不断增长和藻类生物炼制的发展，对藻类提取的生物聚合物的高价值应用的需求日益增长。这种生物聚合物在生物医学领域的利用可以被认为是最有吸引力的应用之一，但实施起来具有挑战性。历史上，从海藻中提取的多糖长期以来一直用于生物医学研究，例如用于电泳和细菌培养的琼脂糖凝胶。为了克服多糖目前面临的挑战并帮助进一步开发高附加值应用，需要概述从海藻到生物医学应用的整个多糖历程。这包括藻类培养、提取、化学、表征、加工以及对软物质与生物体相互作用的理解。在这篇综述中，我们介绍了本质上形成水凝胶的藻类多糖：藻酸盐、角叉菜胶、绿藻硫化多糖、淀粉、琼脂糖、卟啉和（纳米）纤维素，并根据其凝胶机制对它们进行分类。本综述的重点进一步放在获得纯多糖的培养和提取策略、它们的结构-性质关系、化学主链修饰的当前进展以及如何使用这些修饰来调节多糖特性。介绍了表征多糖水凝胶每种组织尺度的可用技术，并讨论了它们与生物系统相互作用的影响。最后，提出了整个领域的预期发展前景，以及进一步利用从藻类中提取的形成水凝胶的多糖如何彻底改变当前的藻类产业。