INQUIMAE-CONICET and DQIAQF, University of Buenos Aires, School of Sciences, Ciudad Universitaria, Pabellón 2, Ciudad Autónoma de Buenos Aires C1428EHA, Argentina.
Department of Biomedical Engineering, Department of Chemistry and Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois 60208, USA.
Soft Matter. 2021 Mar 18;17(10):2791-2802. doi: 10.1039/d0sm01760d.
Polymer-brush-modified nanopores are synthetic structures inspired by the gated transport exhibited by their biological counterparts. This work theoretically analyzes how the reversible crosslinking of a polymer network by soluble species can be used to control transport through nanochannels and pores. The study was performed with a molecular theory that allows inhomogeneities in the three spatial dimensions and explicitly takes into account the size, shape and conformations of all molecular species, considers the intermolecular interactions between the polymers and the soluble crosslinkers and includes the presence of a translocating particle inside the pore. It is shown than increasing the concentration of the soluble crosslinkers in bulk solution leads to a gradual increase of its number within the pore until a critical bulk concentration is reached. At the critical concentration, the number of crosslinkers inside the pore increases abruptly. For long chains, this sudden transition triggers the collapse of the polymer brush to the center of the nanopore. The resulting structure increases the free-energy barrier that a translocating particle has to surmount to go across the pore and modifies the route of translocation from the axis of the pore to its walls. On the other hand, for short polymer chains the crosslinkers trigger the collapse of the brush to the pore walls, which reduces the translocation barrier.
聚合物刷修饰的纳米孔是受生物类似物门控传输启发而设计的合成结构。这项工作从理论上分析了可溶性物质可逆交联聚合物网络如何用于控制纳米通道和孔中的传输。研究采用了一种分子理论，该理论允许在三个空间维度上存在非均匀性，并明确考虑了所有分子物种的大小、形状和构象，考虑了聚合物和可溶性交联剂之间的分子间相互作用，并包括在孔内存在迁移粒子。结果表明，增加本体溶液中可溶性交联剂的浓度会导致其在孔内的数量逐渐增加，直到达到临界本体浓度。在临界浓度时，孔内交联剂的数量突然增加。对于长链，这种突然的转变会引发聚合物刷向纳米孔中心坍塌。由此产生的结构增加了迁移粒子必须克服的自由能势垒，从而改变了从孔轴到其壁的迁移路径。另一方面，对于短链聚合物，交联剂会引发刷状结构向孔壁坍塌，从而降低了迁移势垒。
