Tailoring the water structure and transport in nanotubes with tunable interiors

Self-assembly of cyclic peptide nanotubes (CPNs) in polymer thin films has opened up the possibility of creating separation membranes with tunable nanopores that can differentiate molecules at the sub-nanometer level. While it has been demonstrated that the interior chemistry of the CPNs can be tail...

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Bibliographic Details
Published in:Nanoscale 2015-01, Vol.7 (1), p.121-132
Main Authors: Ruiz, Luis, Wu, Yuanqiao, Keten, Sinan
Format: Article
Language:English
Subjects:
Adsorption
Biomimetic Materials - chemical synthesis
Computer Simulation
Diffusion
Functional groups
Hydrophobic and Hydrophilic Interactions
Materials Testing
Models, Chemical
Models, Molecular
Nanopores - ultrastructure
Nanostructure
Nanotubes
Nanotubes - chemistry
Nanotubes - ultrastructure
Porosity
Self assembly
Separation
Transport
Transport properties
Water - chemistry
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Summary:Self-assembly of cyclic peptide nanotubes (CPNs) in polymer thin films has opened up the possibility of creating separation membranes with tunable nanopores that can differentiate molecules at the sub-nanometer level. While it has been demonstrated that the interior chemistry of the CPNs can be tailored by inserting functional groups in the nanopore lumen (mCPNs), a design strategy for picking the chemical modifications that lead to particular transport properties has not been established. Drawing from the knowledgebase of functional groups in natural amino acids, here we use molecular dynamics simulations to elucidate how bioinspired mutations influence the transport of water through mCPNs. We show that, at the nanoscale, factors besides the pore size, such as electrostatic interactions and steric effects, can dramatically change the transport properties. We recognize a novel asymmetric structure of water under nanoconfinement inside the chemically functionalized nanotubes and identify that the small non-polar glycine-mimic groups that minimize the steric constraints and confer a hydrophobic character to the nanotube interior are the fastest transporters of water. Our computationally developed experiments on a realistic material system circumvent synthetic challenges, and lay the foundation for bioinspired principles to tailor artificial nanochannels for separation applications such as desalination, ion-exchange and carbon capture.
ISSN:2040-3364
2040-3372
DOI:10.1039/c4nr05407e