Diener Michael, Adamcik Jozef, Mezzenga Raffaele
Department of Health Sciences and Technology, Swiss Federal Institute of Technology Zurich, 8092 Zurich, Switzerland.
Department of Materials, Swiss Federal Institute of Technology Zurich, 8092 Zurich, Switzerland.
ACS Macro Lett. 2020 Sep 15;9(9):1310-1317. doi: 10.1021/acsmacrolett.0c00501. Epub 2020 Aug 26.
The linear polysaccharide λ-carrageenan is the only one among the carrageenans not forming secondary, tertiary, and quaternary structures in the presence of inorganic ions. Chloroquine (CQ) is a well-established antimalaria drug also recently discussed in therapeutics against the COVID-19 pandemic. The interaction of this polysaccharide-ionic drug pair was investigated by combining UV-vis spectrophotometry and atomic force microscopy (AFM) imaging. A decrease of the UV peak assigned to free CQ and the occurrence of isosbestic points indicate the formation of complexes. High-resolution AFM height images revealed an increasing height of the single polysaccharide chains in the random coil state upon addition of CQ, indicating the formation of a secondary structure, followed by higher hierarchical aggregates. The disappearance of higher-ordered structures and the recovery of polysaccharide chains with primary structure were observed by introducing inorganic cations (Na, K, Ca), replacing the condensed CQ and paving the way to reversible ion-induced drug release.
线性多糖λ-卡拉胶是卡拉胶中唯一一种在无机离子存在下不形成二级、三级和四级结构的多糖。氯喹（CQ）是一种成熟的抗疟疾药物，最近也被用于治疗新冠疫情。通过结合紫外可见分光光度法和原子力显微镜（AFM）成像研究了这种多糖-离子药物对的相互作用。归属于游离CQ的紫外峰降低以及等吸收点的出现表明形成了复合物。高分辨率AFM高度图像显示，加入CQ后，处于无规卷曲状态的单条多糖链高度增加，表明形成了二级结构，随后形成了更高层次的聚集体。通过引入无机阳离子（Na、K、Ca），观察到高阶结构消失，多糖链恢复为一级结构，取代了凝聚的CQ，为可逆的离子诱导药物释放铺平了道路。
