文献：Preparation of Nanoparticles Loaded with Quercetin and Effects on Bacterial Biofilm and LPS-Induced Oxidative Stress in Dugesia japonica

文献链接：https://link.springer.com/article/10.1007/s12010-023-04543-5

作者：Na Sun , Xin Jiang , Qingqing Meng , Han Jiang , Zuoqing Yuan , Jianyong Zhang

相关产品：FITC-chitosan（FITC-壳聚糖）

原文摘要：

Quercetin is a kind of flavonol compound, which has been widely concerned because of its good pharmacological effects. However, its poor water solubility and poor oral absorption limit its application. To address the above problems, the optimal technological conditions for preparing quercetin-loaded chitosan sodium alginate nanoparticles (Q-CSNPs) were obtained through single-factor experiment method. Q-CSNPs were characterized by particle size analyzer, scanning electron microscope (SEM), transmission electron microscope (TEM), and Fourier transform infrared spectroscopy (FTIR). Biofilm experiment evaluated the antibacterial activity of five different concentrations of Q-CSNPs against Escherichia coli and Staphylococcus aureus. DPPH and hydroxyl radical scavenging experiments determined their antioxidant activity. The effect of Q-CSNPs labeled with FITC on the oxidative stress of planarian was determined. The results showed that quercetin was successfully encapsulated and had good antibacterial and antioxidant capacity in vitro. In vivo experiments of planarians also showed that Q-CSNPs could inhibit the oxidative stress induced by lipopolysaccharide (LPS) and especially alleviate the decrease of CAT activity and the increase of MDA content in planarians induced by LPS. After being supported by future in vivo studies, this preparation will provide research possibilities for the development of quercetin nano-drugs, quercetin dietary supplement, and so on.

FITC-chitosan：

FITC - chitosan 是由壳聚糖（chitosan）和异硫氰酸荧光素（FITC）组成的化合物。壳聚糖是一种天然的多糖，它是由自然界普遍存在的几丁质（chitin）经过脱乙酰作用得到的。几丁质主要来源于甲壳类动物的外壳，壳聚糖分子中含有大量的氨基和羟基，这些官能团使得壳聚糖具有许多化学和生物学性质。异硫氰酸荧光素（FITC）是一种常用的荧光标记试剂，其激发波长约为 495nm，发射波长约为 519nm，能够产生明亮的绿色荧光，可用于标记生物分子以进行检测和成像。基于FITC-chitosan的性能，文献介绍如下：

图：FITC 结构式

标记过程：

取适量的Q - CSNPs 溶液置于干净的容器中，根据Q - CSNPs 的量，计算所需的 FITC - chitosan 用量，一般按照摩尔比或质量比进行添加。将计算好的 FITC - chitosan 缓慢加入到 Q - CSNPs 溶液中，同时在磁力搅拌器上缓慢搅拌，使两者充分混合均匀。反应体系的总体积可根据实际情况确定。将反应容器置于暗处或用铝箔包裹避光，因为 FITC 对光敏感，光照可能导致其降解或标记效果不稳定。在室温下搅拌反应一段时间，以确保 FITC - chitosan 与 Q - CSNPs 上的壳聚糖或其他可反应基团充分反应。反应过程中可以通过定期取样，用荧光光谱仪检测溶液的荧光强度变化来监测反应进程。反应结束后，将反应混合液转移至透析袋中，透析袋事先用缓冲溶液充分浸泡处理。将透析袋置于大量的缓冲溶液中进行透析，透析时间根据 FITC - chitosan 的分子量和透析袋的截留性能而定，期间要多次更换透析外液，以彻底去除未反应的 FITC - chitosan 和其他小分子杂质。

图：流程示意

结论：

该文献成功制备出负载槲皮素壳聚糖海藻酸钠纳米颗粒（Q-CSNPs），并用FITC-chitosan成功标记Q-CSNPs。实验表明，Q-CSNPs具有良好的体外抗菌和抗氧化能力，能抑制脂多糖（LPS）引起的氧化应激，可以缓解LPS引起的涡虫体内CAT活性的降低和MDA含量的增加。FITC-chitosan在实验过程中发挥良好的标记性能。