Molecular machines for transmembrane ion transport

In nature, cellular metabolism in organisms depends on the spatial compartments of ions, small molecules and macromolecules. Substance transport between spatial compartments is performed by natural membrane proteins such as ion channels and ion pumps. These biological machines play an important role in various physiological functions by precisely mediating transmembrane transport processes. Inspired by these marvels, chemists have devoted their efforts to developing artificial molecular machines to mimic the ion transport behavior of natural membrane proteins. Compared with natural membrane proteins, artificial ion transport systems across membranes have advantages in terms of structural simplicity, stability and cost-effectiveness. This review outlines recent advances in artificial molecular machines to mimic the ion transport function of natural membrane proteins and achieve efficient and selective transmembrane transport. Different types of molecular machine-based transmembrane ion transport systems, such as unimolecular transmembrane ion transport systems, polymer transmembrane ion transport systems and supramolecular transmembrane ion transport systems, are analyzed to explore their potential applications in lipid bilayers. Subsequently, the challenges and future directions of molecular machines in regulating transmembrane ion transport are discussed. It is anticipated that this review will provide some inspiring insights and future directions for the construction of molecular machine-based transport systems with higher levels of structure, properties, functions, and practical applications.