Phase behavior and critical activated dynamics of limited-valence DNA nanostars
Phase behavior and critical activated dynamics of limited-valence DNA nanostars
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DOI：
10.1073/pnas.1304632110
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发表时间：
2013-09-24
影响因子：
11.1
通讯作者：
Bellini, Tommaso
中科院分区：
文献类型：
--
作者：
Biffi, Silvia;Cerbino, Roberto;Bellini, Tommaso
具有定向相互作用的胶体粒子是实现具有非常规相行为的新型胶体材料的关键。在这里，我们利用DNA自组装产生大量的“DNA星”与三个或四个粘性终端，模仿分子与控制有限的价。这类分子的溶液呈现出具有上临界点的共溶曲线，其温度和浓度随化合价而降低。当从高温接近临界点时，散射光的强度以幂律发散，而强度时间自相关函数显示出令人惊讶的两步弛豫，不知何故让人想起玻璃材料。缓慢的弛豫时间表现出阿克里尼乌斯行为，没有临界的迹象，展示了一个独特的情况下，临界减缓的浓度波动是从属于大的寿命的DNA键，在聚合物溶液中的临界动力学相关的类比。DNA nanostars的平衡和动态行为的结合表明了DNA分子在使集体性质和自组装材料的途径多样化方面的潜力，超出了普通分子流体可获得的现象范围。
Colloidal particles with directional interactions are key in the realization of new colloidal materials with possibly unconventional phase behaviors. Here we exploit DNA self-assembly to produce bulk quantities of "DNA stars" with three or four sticky terminals, mimicking molecules with controlled limited valence. Solutions of such molecules exhibit a consolution curve with an upper critical point, whose temperature and concentration decrease with the valence. Upon approaching the critical point from high temperature, the intensity of the scattered light diverges with a power law, whereas the intensity time autocorrelation functions show a surprising two-step relaxation, somehow reminiscent of glassy materials. The slow relaxation time exhibits an Arrhenius behavior with no signs of criticality, demonstrating a unique scenario where the critical slowing down of the concentration fluctuations is subordinate to the large lifetime of the DNA bonds, with relevant analogies to critical dynamics in polymer solutions. The combination of equilibrium and dynamic behavior of DNA nanostars demonstrates the potential of DNA molecules in diversifying the pathways toward collective properties and self-assembled materials, beyond the range of phenomena accessible with ordinary molecular fluids.