Facilitated Water Transport through Graphene Oxide Membranes Functionalized with Aquaporin-Mimicking Peptides

Abstract

Water purification by membranes is widely investigated to address concerns related to the scarcity of clean water. Achieving high flux and rejection simultaneously is a difficult challenge using such membranes because these properties are mutually exclusive in common artificial membranes. Nature has developed a method for this task involving water-channel membrane proteins known as aquaporins. Here, the design and fabrication of graphene oxide (GO)-based membranes with a surface-tethered peptide motif designed to mimic the water-selective filter of natural aquaporins is reported. The short RF8 (RFRFRFRF, where R and F represent arginine and phenylalanine, respectively) octapeptide is a concentrated form of the core component of the Ar/R (aromatic/arginine) water-selective filter in aquaporin. The resulting GO-RF8 shows superior flux and high rejection similar to natural aquaporins. Molecular dynamics simulation reveal the unique configuration of RF8 peptides and the transport of water in GO-RF8 membranes, supporting that RF8 effectively emulates the core function of aquaporins.

Graphene oxide membranes grafted with aquaporin-mimicking peptides are designed and fabricated to simultaneously achieve high flux and rejection, which is a challenging task for water-treatment membranes. Rather than transferring the whole aquaporin from the cells, graphene oxide membranes with a short octapeptide successfully emulate the core function of aquaporins for facilitated water permeation and high dye rejection.

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