CNR-ISC and Department of Physics, Sapienza University of Rome, Piazzale A. Moro 2, 00185 Rome, Italy.
Department of Chemical Science and Technologies, University of Rome Tor Vergata, Via della Ricerca Scientifica I, 00133 Rome, Italy.
Sci Adv. 2023 Mar 10;9(10):eadg4392. doi: 10.1126/sciadv.adg4392.
Among hydrocolloids, gellan is one of the most studied polysaccharides due to its ability to form mechanically stable gels. Despite its long-standing use, the gellan aggregation mechanism is still not understood because of the lack of atomistic information. Here, we fill this gap by developing a new gellan force field. Our simulations offer the first microscopic overview of gellan aggregation, detecting the coil to single-helix transition at dilute conditions and the formation of higher-order aggregates at high concentration through a two-step process: first, the formation of double helices and then their assembly into superstructures. For both steps, we also assess the role of monovalent and divalent cations, complementing simulations with rheology and atomic force microscopy experiments and highlighting the leading role of divalent cations. These results pave the way for future use of gellan-based systems in a variety of applications, from food science to art restoration.
在水凝胶中，由于其能够形成机械稳定的凝胶，因此黄原胶是研究最多的多糖之一。尽管黄原胶的使用历史悠久，但由于缺乏原子信息，其聚集机制仍不清楚。在这里，我们通过开发一种新的黄原胶力场来填补这一空白。我们的模拟提供了黄原胶聚集的第一个微观概述，在稀溶液条件下检测到了从线圈到单链的转变，并且通过两步过程在高浓度下形成了更高阶的聚集体：首先是形成双螺旋，然后将它们组装成超结构。对于这两个步骤，我们还评估了单价和二价阳离子的作用，用流变学和原子力显微镜实验补充了模拟，并强调了二价阳离子的主导作用。这些结果为未来在各种应用中使用基于黄原胶的系统铺平了道路，从食品科学到艺术品修复。
