Voltage-Gated\nTransport of Nanoparticles across Free-Standing\nAll-Carbon-Nanotube-Based Hollow-Fiber Membranes

Abstract

Understanding\nthe mechanism underlying controllable transmembrane\ntransport observed in biological membranes benefits the development\nof next-generation separation membranes for a variety of important\napplications. In this work, on the basis of common structural features\nof cell membranes, a very simple biomimetic membrane system exhibiting\ngated transmembrane performance has been constructed using all-carbon-nanotube\n(CNT)-based hollow-fiber membranes. The conductive CNT membranes with\nhydrophobic pore channels can be positively or negatively charged\nand are consequently capable of regulating the transport of nanoparticles\nacross their pore channels by their “opening” or “closing”.\nThe switch between penetration and rejection of nanoparticles through/by\nCNT membranes is of high efficiency and especially allows dynamic\ncontrol. The underlying mechanism is that CNT pore channels with different\npolarities can prompt or prevent the formation of their noncovalent\ninteractions with charged nanoparticles, resulting in their rejection\nor penetration by/through the CNT membranes. The theory about noncovalent\ninteractions and charged pore channels may provide new insight into\nunderstanding the complicated ionically and bimolecularly gated transport\nacross cell membranes and can contribute to many other important applications\nbeyond the water purification and resource recovery demonstrated in\nthis study.