Selective Unidirectional Transport of Protons in Sub-Nanoporous Membranes Inspired by the Influenza A M2 Channel for Nanofluidic Ionic Diodes

Abstract

Proton transport is involved in many biological processes, such as viral replication and enzymatic catalysis. However, one-way transmission is the premise of the realization of the above functions. Actually, the unidirectional transport of protons is significant not only for biology but also for practical applications. Herein, inspired by the influenza A M2 channel, a sub-nanoporous proton transport membrane was constructed by layer-by-layer assembly of two oppositely charged pillar[n]arenes with sub-nanometer cavities. A good selectivity of the proton transport membranes to protons was achieved by exploiting the size effect of sub-nanometer pores. And the proton transport membrane has a transport capacity of 459 μM·m–2·h–1 for protons. For nanofluidic diodes, the construction of the sub-nanopore proton transport membrane was very meaningful. For energy conversion applications such as catalytic transformations, although the flux cannot meet the application in these fields, the development of this membrane provides an idea for it. What is more, it can help deepen the understanding of the relationship between sub-nanostructure and function.