In many biopolymer solutions, attractive interactions that stabilize finite-sized clusters at low concentrations also promote phase separation at high concentrations. Here we study a model biopolymer system that exhibits the opposite behavior, whereby self-assembly of DNA oligonucleotides into finite-sized, stoichiometric clusters tends to inhibit phase separation. We first use microfluidics-based experiments to map a novel phase transition in which the oligonucleotides condense as the temperature increases at high concentrations of divalent cations. We then show that a theoretical model of competition between self-assembly and phase separation quantitatively predicts changes in experimental phase diagrams arising from DNA sequence perturbations. Our results point to a general mechanism by which self-assembly shapes phase boundaries in complex biopolymer solutions.

中文翻译：

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自组装和相分离之间的竞争控制着 DNA 液体的高温冷凝

在许多生物聚合物溶液中，在低浓度下稳定有限尺寸簇的吸引相互作用也会在高浓度下促进相分离。在这里，我们研究了一个表现出相反行为的模型生物聚合物系统，即 DNA 寡核苷酸自组装成有限大小的化学计量簇往往会抑制相分离。我们首先使用基于微流体的实验来绘制一种新的相变，其中寡核苷酸在高浓度的二价阳离子下随着温度的升高而凝结。然后，我们证明自组装和相分离之间的竞争理论模型定量预测了 DNA 序列扰动引起的实验相图的变化。我们的结果指出了自组装在复杂生物聚合物溶液中形成相界的一般机制。