Biomimetic Functionalities of Angstrom-Scale Ion Channels: A Mini Review

Recent advancements in porous two-dimensional (2D) membranes, along with progress in nanoscale processing and measurement technologies have paved the way for the utilization of Ǻngström-scale channels, facilitating control of water and ion transport. Notably, ion transport is a key phenomenon in major applications such as salinity-gradient power generation, ion separation, iontronics, ultrasensitive sensing, and energy storage and conversion. Nature already demonstrates Ǻngström-scale ion transport phenomena through biological channels in cell membranes, achieving versatile functions, including ion selectivity, rectification, and channel gating. This paper explores recent research where synthetic Ǻngström-scale channels mimic these key biological functions. In particular, ion selectivity, rectification, and channel gating have been effectively demonstrated using metal–organic frameworks (MOFs) and covalent organic frameworks (COFs) with structurally embedded pores; in addition, multifunctionalities similar to biological ion channels have been reported. The discovery of various 2D membranes such as MOFs, COFs, Xenes, Mxenes, and MX2 has provided numerous building blocks for realizing detailed and diverse functions comparable to those of biological ion channels, leading to new applications, increased efficiency, and optimized functions. Thus, a comprehensive guide will be essential for fully leveraging these discoveries by linking surface and interfacial structures with transport properties, mechanisms, and functionalities.