Foldamer-Based Ultrapermeable and Highly Selective Artificial Water Channels that Exclude Protons

Arundhati Roy, Jie Shen, Himanshu Joshi, Woochul Song, Yu-Ming Tu, Ratul Chowdhury, Ye Ruijuan, Ning Li, Changliang Ren, Manish Kumar, Aleksei Aksimentiev, and Huaqiang Zeng
Nature Nanotechnology 16(8) 911-917 (2021)
DOI:10.1038/s41565-021-00915-2  BibTex

Highlight

A class of biomimetic, helically folded pore-forming polymeric foldamers can serve as long-sought-after highly selective ultrafast water-conducting channels exceeding those of aquaporins with high water-over-monovalent-ion transport selectivity conferred by the modularly tunable hydrophobicity of the interior pore surface. 

Abstract

The outstanding capacity of aquaporins (AQPs) for mediating highly selective superfast water transport has inspired the recent development of supramolecular monovalent ion-excluding artificial water channels (AWCs). AWC-based bioinspired membranes are proposed for desalination, water purification, and other separation applications. While some recent progress has been made in synthesizing AWCs that approach the water permeability and ion selectivity of AQPs, a hallmark feature of AQPs—high water transport while excluding protons-has not been reproduced. We report a class of biomimetic, helically folded pore-forming polymeric foldamers that can serve as long-sought-after highly selective ultrafast water-conducting channels with performance exceeding those of AQPs (1.1 × 1010 water molecules per second for AQP1, with high water-over- monovalent-ion transport selectivity (~108 water molecules over Cl- ion) conferred by the modularly tunable hydrophobicity of the interior pore surface. The best-performing AWC reported here delivers water transport at an exceptionally high rate, namely, 2.5 times that of AQP1, while concurrently rejecting salts (NaCl and KCl) and even protons.

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700 ns long all-atom equilibrium MD simulation trajectory of 3-LA channels respectively. A cut-away view of the system is presented to illustrate the transmembrane water permeation. A carbon atom of the amine-group of each POPC molecule is shown as a large green sphere, whereas the rest of each molecule is shown as a thick green line. The channel is shown using a molecular surface representation. The lipid anchoring alkyl chains (C8H17) of the channel are shown in licorice blue. The LA anchors at the ends of the channels are shown in yellow spheres. The water molecules inside and near the channels are shown using red (oxygen) and white (hydrogen) spheres. The rest of the water and ions are not shown.