School of Materials Science, Japan Advanced Institute of Science and Technology, Asahidai, Nomi, Ishikawa 923-1292, Japan, Department of Polymer Science and Engineering, Graduate School of Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa, 992-8510, Japan, and Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan.
Biomacromolecules. 2010 Nov 8;11(11):3172-7. doi: 10.1021/bm101012u. Epub 2010 Oct 5.
The self-organization behavior of an extracellular polysaccharide (sacran) extracted from the cyanobacterium Aphanothece sacrum in response to lanthanoid ion adsorption was investigated. Consequently, cryogenic TEM images revealed that sacran could be cross-linked by Nd(3+) trivalent ions and formed a fibrous nanostructural network containing water. Furthermore, sacran adsorbed trivalent metal ions at a 3:1 ratio, which was the theoretical ionic adsorption and showed more efficient adsorption than alginate based on electric conductivity titration. The critical gelation concentrations, Cg, where sacran formed tough gels upon metal ion binding were estimated. The Cg for trivalent metal ions was lower than that for divalent ions, and the Cg for lanthanoid ions was particularly low at 10(-3) to 10(-4) M, changing every four elemental numbers. The extracellular matrix of Aphanothece sacrum, sacran, may adsorb metal ions to create fibrous nanostructures that reinforce the jelly matrix.
从蓝藻 Aphanothece sacrum 中提取的胞外多糖（沙聚糖）对镧系离子吸附的自组织行为进行了研究。结果表明，低温 TEM 图像显示，沙聚糖可以与 Nd(3+)三价离子交联，并形成含有水的纤维状纳米结构网络。此外，沙聚糖以 3:1 的比例吸附三价金属离子，这是理论上的离子吸附，根据电导率滴定显示，其吸附效率高于基于海藻酸盐的吸附。估计了沙聚糖在结合金属离子时形成坚韧凝胶的临界胶凝浓度（Cg）。三价金属离子的 Cg 低于二价离子，而镧系离子的 Cg 特别低，在 10(-3) 到 10(-4) M 之间，每隔四个元素数就会发生变化。蓝藻 Aphanothece sacrum 的细胞外基质沙聚糖可能会吸附金属离子，形成纤维状纳米结构，从而增强果冻基质。
