Transport channels with ultrahigh K+ selectivity over other ions play a crucial role for living beings, but constructing ionic channels with promising K+ selectivity and permeability remains a challenge. Here, an asymmetric bilayer membrane based on MXene (Ti3C2Tx) lamellar channels consisting of a recognition layer (RL) on top of an enhancement layer (EL) exhibits an amazing Matthew effect: amplification of the preferred transport of K+, resulting in an excellent K+-separation performance. The K+ ion is selected by the 1-aza-18-crown-6 ether-modified RL, owing to preferential affinity energy, and then rapidly transported as a hydrated ion through the EL, based on the confinement effect. Other undesired ions such as Na+ are hindered from entering the RL by the preferred K+ occupation of the crown ether. The MXene (Ti3C2Tx)-based Matthew membrane presents high K+-permeation rates of 0.1–0.2 mol∙m−2∙h−1, with a significant K+/Na+ selectivity of 5–9. The molecular separation mechanism of the Matthew membrane is investigated deeply to explore the nature of the Matthew amplification effect on K+ sieving, where the precise matching of the RL and EL within the membrane governs the fast K+ permeation with good selectivity. The asymmetric structure of our Matthew membrane is the key to understanding the biological function of ion channels for precise and fast ion transport, which will guide us in the creation of artificial ion channels or membranes.

中文翻译：

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Matthew MXene （Ti3C2Tx） 层状膜作为钾筛放大器


与其他离子相比，具有超高 K+ 选择性的传输通道对生物起着至关重要的作用，但构建具有良好 K+ 选择性和渗透性的离子通道仍然是一个挑战。在这里，基于 MXene （Ti3C2Tx） 层状通道的不对称双层膜由增强层 （EL） 顶部的识别层 （RL） 组成，表现出惊人的马修效应：放大 K+ 的优选转运，从而获得出色的 K+ 分离性能。由于优先亲和能，K+ 离子被 1-氮杂-18-冠-6 醚修饰的 RL 选择，然后根据限制效应以水合离子的形式通过 EL 快速传输。其他不需要的离子，如 Na+ 受到冠醚的优选 K+ 占据的阻碍进入 RL。基于 MXene （Ti3C2Tx） 的 Matthew 膜具有 0.1-0.2 mol∙m-2∙h-1 的高 K+ 渗透率，具有 5-9 的显著 K+/Na+ 选择性。深入研究了 Matthew 膜的分子分离机制，以探索 Matthew 扩增效应对 K+ 筛分的影响，其中膜内 RL 和 EL 的精确匹配控制了快速 K+ 渗透，具有良好的选择性。我们的 Matthew 膜的不对称结构是了解离子通道精确快速离子传输生物学功能的关键，这将指导我们创建人工离子通道或离子膜。