文献：Impact of encapsulating a probiotic (Pediococcuspentosaceus Li05) within gastro-responsive microgels on Clostridium difficile infections

文献链接：https://www.nstl.gov.cn/paper_detail.html?id=20b849b8fb00fa915b6a66a53c6658b1

作者：Jiaojiao Xie,Mingfei Yao, Yanmeng Lu,Mengjia Yu,b Shengyi Han, David J. McClements, c Hang Xiao and Lanjuan Li

相关产品：fluorescently label the alginate  荧光标记海藻酸盐

原文摘要：Antibiotic treatment is often followed by Clostridium difficile infection (CDI), which causes severe diarrhea and other health issues. Oral administration of Pediococcus pentosaceus Li05 (Li05) has been shown to have great potential in preventing CDI. However, the viability of Li05 is greatly reduced during storage and passage through the gastrointestinal (GI) tract, which limits its biological activity. In this study, a gastroresponsive microgel was designed to encapsulate and protect Li05 to enhance its efficacy against CDI.The viability of Li05 encapsulated within the microgels was significantly enhanced during long-term storage and after exposure to simulated GI fluids. Moreover, this gastro-responsive microgel led to greater sustained release of the probiotic. In a mouse CDI model, we found that encapsulated Li05 was better at inhibiting C. difficile infection than nonencapsulated Li05, as demonstrated through analysis of the probiotic survival rate, spleen weight, colonic histology, and inflammatory cytokine levels. Moreover, the gut microbial diversity was enriched by treatment with encapsulated Li05. These results suggest that encapsulating Li05 within biopolymer microgels may enhance its ability to prevent and treat CDI using functional foods, supplements, or pharmaceuticals.

海藻酸盐是应用广的制造微凝胶的生物聚合物之一，从海藻中提取。从化学的角度来看，它的组成部分是d-甘露糖酸和l-葡萄糖醛酸通过糖苷键连接在一起。基于阴离子海藻酸盐分子通过阳离子钙离子强交联的注射/凝胶化方法可以由海藻酸盐形成微凝胶。天然淀粉和修饰淀粉曾被用于开发益生菌微凝胶的填充材料。假设，淀粉的存在可以通过抑制体内损伤成分（如胃酸、胆盐或消化酶）向微凝胶内部的扩散，从而增强li05负载的海藻酸盐微凝胶的功能性能。形成海藻酸盐/淀粉（AS）微凝胶来封装一种敏感的益生菌（Li05），以提高其对CDI的Therapeutic effect 。在长期储存和模拟GI条件下，评估装载li05的微凝胶的活性和释放行为。

图为：微凝胶的制备工艺小鼠模型协议的示意图

海藻酸盐-淀粉微凝胶的制备：

海藻酸盐-淀粉微凝胶的制备工艺概述如图所示。将海藻酸钠溶液分别与相同体积的淀粉悬浮液混合，得到的溶液分别称为A、A4S1、A2S1、A1S1和A1S2组（数字为海藻酸盐-淀粉质量比）。然后，将细胞悬液加入上述溶液中，在室温下均质。然后将获得的混合物以的喷嘴，苏黎世通过微封装单元。由喷嘴产生的海藻酸盐液滴进入氯化钙交联溶液后立即形成微凝胶。然后将微凝胶悬液搅拌，使微凝胶硬化，然后用生理盐水缓冲液冲洗三次并收集。其中一部分微凝胶在冷冻一段时间后再冷冻干燥，另一部分在保存，以模拟长期保存条件。以非封装的益生菌作为对照。

图为：具有不同A/S比值的AS微凝胶的表征

结论：用光学显微镜来表征当配方中加入淀粉含量的增加时，湿微凝胶结构的变化。微凝胶都大致是球形的。A1S1与A1S2随着微凝胶中淀粉与海藻酸盐的比例的增加，它们从透明变为不透明，表明淀粉颗粒的光散射增加。然而，微凝胶的整体尺寸和形状没有明显的变化，这说明淀粉颗粒没有干扰颗粒的形成过程。用碘溶液染色，检测淀粉颗粒在微凝胶中的分布。淀粉颗粒明显位于微凝胶内部，并相当均匀地分散在其内部。