Network formation in dilute amylose and amylopectin studied by TEM
Network formation in dilute amylose and amylopectin studied by TEM
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DOI：
10.1021/ma000242j
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发表时间：
2000-08-22
期刊：
影响因子：
5.5
通讯作者：
Chanzy, H
中科院分区：
文献类型：
--
作者：
Putaux, JL;Buléon, A;Chanzy, H
用透射电子显微镜（TEM）研究了直链淀粉和支链淀粉稀溶液的回生或再沉淀。负染色，阴影，和cryo-TEM相结合，以研究在沉淀的不同阶段的分子组装体的形态。直链淀粉分形网络在几天内形成。它们被描述为基本半结晶10-15 nm单元的簇，通过分子缔合成平行双螺旋而形成，通过含有松散组织的链的无定形部分连接。这些网络随后凝聚，产生厚的聚集体。发现支链淀粉形成类似的网络，其分支也具有10-15 nm的横向宽度。基本单元被认为是通过分子的短侧支缔合成平行双螺旋而形成的纳米晶体簇。由于支链淀粉网络在该浓度下在溶液中稳定数月，并且没有发生任何进一步的聚集，因此认为分子的支链构型阻碍了微晶的长规模重排。
The retrogradation, or reprecipitation, of dilute amylose and amylopectin aqueous solutions was investigated by transmission electron microscopy (TEM). Negative staining, shadowing, and cryo-TEM were combined to study the morphology of the molecular assemblies at different stages of precipitation. Amylose fractal-like networks formed within a few days. They are described as clusters of elementary semicrystalline 10-15 nm units, formed by associations of molecules into parallel double helices, linked by amorphous sections containing loosely organized chains. These networks subsequently condensed, yielding thick aggregates. Amylopectin was found to form similar networks whose branches also had a 10-15 nm lateral width. The elementary units are thought to be clusters of nanocrystals formed by association of the short side branches of the molecule into parallel double helices. As the amylopectin networks were stable in solution at this concentration during several months and did not undergo any further aggregation, the branched configuration of the molecule is believed to hinder the long-scale rearrangement of the crystallites.