Voltage-Triggered Structural Switching of Polyelectrolyte-Modified Nanochannels
Voltage-Triggered Structural Switching of Polyelectrolyte-Modified Nanochannels
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DOI：
10.1021/acs.macromol.0c00082
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发表时间：
2020-04-14
期刊：
影响因子：
5.5
通讯作者：
Tagliazucchi, Mario
中科院分区：
文献类型：
--
作者：
Perez Sirkin, Yamila A.;Szleifer, Igal;Tagliazucchi, Mario
合成的固态纳米通道修饰的刷是一类重要的刺激响应纳米流体装置。这项工作从理论上解决了一个电压触发的纳米机械门的设计，使用长的纳米通道内的疏水刷的塌陷过渡。在不良的溶剂条件下，接枝到纳米通道内表面的聚乙烯刷可以塌陷到其壁或向其轴拉伸，以形成中心致密塞。所施加的跨膜电位有利于在电场方向上倾斜的β链构象，因此，跨膜电位可以触发从贴靠中心状态到贴靠壁状态的转变。这项工作研究了这种转变作为一个函数的长度的聚合物主链的疏水性，和溶液的pH值和离子强度的双链。确定了实现贴壁结构和贴壁结构之间电压触发突变的最佳条件。本工作还探讨了电压触发的崩塌跃迁对不同尺寸探针粒子输运的影响。结果表明，通道的渗透率与粒子两种不同塌陷状态的选择性之间存在平衡。在这项工作中探索的特定系统中，这种平衡使得结构转变对于门控半径在1 nm范围内的物质的传输最为有效。
Synthetic solid-state nanochannels modified with polyelectrolyte brushes are an important class of stimuli-responsive nanofluidic devices. This work theoretically addresses the design of a voltage-triggered nanomechanical gate using the collapse transition of a hydrophobic polyelectrolyte brush within a long nanochannel. In poor solvent conditions, a polyelectrolyte brush grafted to the inner surface of a nanochannel can either collapse to its walls or stretch toward its axis in order to form a central dense plug. An applied transmembrane potential favors polyelectrolyte chain conformations that are tilted in the direction of the electric field, and therefore, the transmembrane potential can trigger a transition from the collapsed-to-the-center state to the collapsedto-the-wall state. This work studied this transition as a function of the length of the polyelectrolyte chains, the hydrophobicity of the polymer backbone, and the pH and ionic strength of the solution. The optimal conditions to achieve a sharp voltage-triggered transition between the collapsed-to-the-wall and the collapsed-to-the-center structures were identified. This work also explored the effect of the voltage-triggered collapse transition on the transport of probe particles of different sizes. It is shown that there is a balance between the permeability of the channel and the selectivity of the two different collapse states for the particle. In the particular system explored in this work, this balance makes the structural transition mostly effective to gate the transport of species with radii in the similar to 1 nm range.