俄罗斯科学院有机化学研究所Ekaterina R. Gasilova团队报道了超支化和线性多糖的聚电解质配合物——褐藻糖胶/壳聚糖。相关研究成果于2023年12月13日发表于国际顶尖学术期刊《中国高分子科学杂志》。

超支化（HB）和线性多糖的聚电解质复合物（PECs）与线性多糖形成的PECs相比，有望成为更有效的包封剂。

该文研究了HB阴离子多糖褐藻糖胶（FUC）和阳离子线性多糖壳聚糖（CS）之间的PEC。FUC的分子量（MW）为30×。PECs在三种溶剂（水、0.01和0.1mol/L乙酸）中制备，CS的MW为15、110和170kDa，脱乙酰度（DDA）为70%和97%。通过多角度静态和动态光散射研究了PECs和初始FUC的结构。由于FUC含有18wt%的-OSO3基团和5wt%的糖醛酸单元，它是一种“强-弱”共聚阴离子，因此FUC的HB大分子在0.1mol/L AcOH中形成纳米凝胶颗粒，并在水中形成开放支化结构，如Kratky图所证实的。

在混合原始组分的溶液后，PEC结构经历了一个平衡期，其持续时间随着CS的MW而增加。随着电荷化学计量的接近，PEC收缩；分形维数接近1，表明在CS的帮助下相邻FUC分支并排堆积。在电荷补偿附近几乎没有观察到二次聚集，因为它发生在非常窄的区域中。ζ电位反转时的PEC含量取决于溶剂的pH值和CS的DDA。

在0.1 mol/L AcOH中的核壳PECs的极端情况下，通过将FUC纳米凝胶与97%DDA的高MW CS的溶液混合而获得，CS的突出尾部在整个FUC含量范围内形成带正电的壳（10wt%＜WFUC＜90wt%）。研究人员讨论了干燥样品的扫描电子显微镜和原子力显微镜图像与光散射结果的关系。

附：英文原文

Title: Polyelectrolyte Complexes between Hyperbranched and Linear Polysaccharides: Fucoidan/Chitosan

Author: Ekaterina R. Gasilova, Daria N. Poshina, Aleksandra O. Sitnikova, Natalia N. Saprykina, Yury A. Skorik

Issue&Volume: 2023-12-13

Abstract: Polyelectrolyte complexes (PECs) of hyperbranched (HB) and linear polysaccharides are promising as more effective encapsulation agents compared to PECs formed by linear polysaccharides. We investigated the PECs between the HB anionic polysaccharide fucoidan (FUC) and the cationic linear polysaccharide chitosan (CS). The FUC had a molecular weight (MW) of 30×106. The PECs were prepared in three solvents (water, 0.01 and 0.1 mol/L acetic acid) with CS of MW of 15, 110 and 170 kDa, and deacetylation degrees (DDA) of 70% and 97%. The structures of the PECs and the initial FUC were investigated by multi-angle static and dynamic light scattering. As the FUC contained 18 wt% of ―OSO3 groups and 5 wt% of uronic acid units, it was a "strong-weak" copolyanion, so the HB macromolecules of the FUC formed nanogel particles in 0.1 mol/L AcOH and open branched structures in water, as confirmed by the Kratky plots. After mixing the solutions of original components, the PEC structures underwent an equilibration period, the duration of which increased with the MW of CS. As the charge stoichiometry was approached, the PECs shrank; the fractal dimension approached unity, indicating the side-by-side packing of adjacent FUC branches with the help of CS. Secondary aggregation in the vicinity of the charge compensation was hardly observed, as it occurred in a very narrow region. The PEC content at the ζ-potential inversion depended on solvents’ pH and the DDA of CS. In the extreme case of core-shell PECs in 0.1 mol/L AcOH, obtained by mixing FUC nanogels with the solutions of high MW CS of 97% DDA, the protruding tails of CS formed a positively charged shell in the whole range of FUC content (10 wt% < WFUC < 90 wt%). Scanning electron microscopy and atomic force microscopy images of dried samples were discussed in relation to the light scattering results.

DOI: 10.1007/s10118-024-3069-9

Source: https://www.cjps.org/en/article/doi/10.1007/s10118-024-3069-9/