dorsal/arxiv
View SchemaModeling the selective partitioning of cations into negatively charged nanopores in water
| Authors | Lu Yang, Shekhar Garde |
|---|---|
| Categories | |
| ArXiv ID | physics/0702065 |
| URL | https://arxiv.org/abs/physics/0702065 |
| Journal | The Journal of Chemical Physics 126, 2007 |
Abstract
Partitioning and transport of water and small solutes into and through nanopores is important to a variety of chemical and biological processes and applications. Here we study the partitioning of positive ions of increasing size into the pore interior using extensive molecular dynamics simulations. Despite the simplicity of the simulation system, the results provide new and useful insights on both the pore hydration and ion partitioning. For low negative charge densities on the pore, the driving force for partitioning of positive ions into the pore is weak, and no partitioning is observed. Increasing the pore charge gradually leads to partitioning of positive ions into the pore. Interestingly, over a range of intermediate negative charge densities, nanopores display both thermodynamic as well as kinetic selectivity toward partitioning of the larger K+ and Cs+ ions into their interior over the smaller Na+ ions. The variation of thermodynamic driving force and the average partitioning time with the pore charge density together suggest the presence of free energy barriers in the partitioning process. We discuss the role of ion hydration in the bulk and in the pore interior as well as of the pore hydration in determining the barrier heights for ion partitioning and the observed thermodynamic and kinetic selectivity.
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"abstract": "Partitioning and transport of water and small solutes into and through\nnanopores is important to a variety of chemical and biological processes and\napplications. Here we study the partitioning of positive ions of increasing\nsize into the pore interior using extensive molecular dynamics simulations.\nDespite the simplicity of the simulation system, the results provide new and\nuseful insights on both the pore hydration and ion partitioning. For low\nnegative charge densities on the pore, the driving force for partitioning of\npositive ions into the pore is weak, and no partitioning is observed.\nIncreasing the pore charge gradually leads to partitioning of positive ions\ninto the pore. Interestingly, over a range of intermediate negative charge\ndensities, nanopores display both thermodynamic as well as kinetic selectivity\ntoward partitioning of the larger K+ and Cs+ ions into their interior over the\nsmaller Na+ ions. The variation of thermodynamic driving force and the average\npartitioning time with the pore charge density together suggest the presence of\nfree energy barriers in the partitioning process. We discuss the role of ion\nhydration in the bulk and in the pore interior as well as of the pore hydration\nin determining the barrier heights for ion partitioning and the observed\nthermodynamic and kinetic selectivity.",
"arxiv_id": "physics/0702065",
"authors": [
"Lu Yang",
"Shekhar Garde"
],
"categories": [
"physics.chem-ph"
],
"journal_ref": "The Journal of Chemical Physics 126, 2007",
"title": "Modeling the selective partitioning of cations into negatively charged nanopores in water",
"url": "https://arxiv.org/abs/physics/0702065"
},
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