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不同pH环境下二价离子对聚电解质链的影响

Effect of divalent ions on the polyelectrolyte chains at different pH
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摘要 基于郎之万动力学方法,研究了不同pH环境下二价反离子对半柔性聚电解质链构象变化的影响。聚电解质用粗粒度的珠簧模型表示,在pH-pK>0时,回转半径几乎不变,随着pH-pK值的降低,聚电解质链的回转半径减小并且逐渐发生了缩合。在实验中,通过改变Mg^2+介导下DNA溶液的pH环境,对DNA进行了原子力显微镜扫描成像,发现DNA在中性和弱酸性环境中保持自由松散状态,当pH降低到4以下,即酸性变强时DNA逐步缩合成球状并达到稳定,这一结果与模拟结果一致。 In this study, the effect of divalent counterions on the conformational change of the semi-flexible polyelectrolyte chains was investigated at different pH based on Langevin’s dynamics. Polyelectrolyte is represented by a coarse-grained bead spring model, with the radius of gyration(Rg) remaining almost constant at pH-pK>0. Rg reduces and the polyelectrolyte chain shrinks as the value of pH-pK decreases. Meanwhile, in the experiment, the atomic force microscopy images of the DNA mediated by Mg^2+ were obtained in different pH environments to denote that the DNA remained in a free and loose state in neutral and weakly acidic environments. At pH<4, i.e., strong acidity, DNA was gradually condensed into a spherical shape and stabilized. Further, the experimental result agrees with the simulation results.
作者 李树行 祝泽栋 徐紫颜 杨光参 LI Shu-hang;ZHU Ze-dong;XU Zi-yan;YANG Guang-can(School of Mathematics and Electronic Information Engineering,Wenzhou University,Wenzhou 325035,China)
出处 《山东科学》 CAS 2019年第4期94-100,共7页 Shandong Science
基金 国家自然科学基金(11574232,11274245)
关键词 郎之万动力学 反离子 聚电解质 PH DNA Langevin’s dynamics counter ion polyelectrolyte pH DNA
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