Phase behaviors of agarose gel
Phase behaviors of agarose gel
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DOI：
10.1063/1.4802968
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发表时间：
2013-04-01
期刊：
影响因子：
1.6
通讯作者：
Tokita, Masayuki
中科院分区：
文献类型：
--
作者：
Morita, Takaharu;Narita, Takayuki;Tokita, Masayuki
我们提出的证据存在相分离的琼脂糖凝胶状态的水和甲醇的混合物作为凝胶溶剂。首先，溶胶-凝胶转变线和浊点线作为琼脂糖的浓度的函数，以及在混合溶剂中的甲醇的浓度通过溶液的准平衡冷却独立地确定。然后通过淬灭低于溶胶-凝胶转变线的溶液来确定亚稳线。我们发现在琼脂糖水溶液体系中，旋节线出现在浊点线之下，并且这两条线都完全埋在溶胶-凝胶转变线之下。因此，浓度波动被冻结在琼脂糖凝胶的聚合物网络中，这促进了所得凝胶的不透明性。用共聚焦激光扫描显微镜（CLSM）成像技术观察琼脂糖凝胶的结构，发现其密度波动在空间上达到微米级。发现当混合溶剂中甲醇浓度增加时，相分离边界向比溶胶-凝胶转变线更高的温度区域移动。结果表明，相分离边界相对于溶胶-凝胶转变线的位置随溶剂的质量而变化。这些结果与溶胶-凝胶转变理论相一致，该理论同时考虑了连接性的发散和热力学不稳定性。(C)2013年作者。除非另有说明，否则所有文章内容均根据Creative Commons Attribution 3.0 Unported License许可。[http：//dx.doi.org/10.1063/1.4802968]
We present evidence for the existence of phase separation in the gel state of agarose having the mixture of water and methanol as the gel solvent. Firstly, the sol-gel transition line and the cloud point line are determined independently as a function of the concentration of agarose as well as the concentration of methanol in the mixed solvent by the quasi-equilibrium cooling of the solutions. Then the spinodal line is determined by quenching the solutions below the sol-gel transition line. We find that the spinodal line appears below the cloud point line and both lines are entirely buried below the sol-gel transition line in the aqueous agarose system. The concentration fluctuations are, therefore, frozen into the polymer network of agarose gel that promotes the opacity of the resultant gel. The structure of agarose gel is observed by the confocal laser scanning microscope (CLSM) imaging technique that reveals that the density fluctuations are grown up to micrometer scale in space. The phase separation boundary is found to shift to the higher temperature region than the sol-gel transition line when the concentration of methanol in the mixed solvent is increased. The results indicate that the position of the phase separation boundary in relative to the sol-gel transition line varies with the quality of solvent. These results are in agreement with the theory of the sol-gel transition in which both the divergence of the connectivity and the thermodynamic instability are taken into account. (C) 2013 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License. [http://dx.doi.org/10.1063/1.4802968]