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Seiferth D, Biggin PC. Exploring the influence of pore shape on conductance and permeation. Biophys J 2024:S0006-3495(24)00449-1. [PMID: 38973159 DOI: 10.1016/j.bpj.2024.07.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2024] [Revised: 06/17/2024] [Accepted: 07/05/2024] [Indexed: 07/09/2024] Open
Abstract
There are increasing numbers of ion channel structures featuring heteromeric subunit assembly, exemplified by synaptic α1βB glycine and α4β2 nicotinic receptors. These structures exhibit inherent pore asymmetry, but the relevance of this to function is unknown. Furthermore, molecular dynamics simulations performed on symmetrical homomeric channels often lead to thermal distortion whereby conformations of the resulting ensemble are also asymmetrical. When functionally annotating ion channels, researchers often rely on minimal constrictions determined via radius-profile calculations performed with computer programs, such as HOLE or CHAP, coupled with an assessment of pore hydrophobicity. However, such tools typically employ spherical probe particles, limiting their ability to accurately capture pore asymmetry. Here, we introduce an algorithm that employs ellipsoidal probe particles, enabling a more comprehensive representation of the pore geometry. Our analysis reveals that the use of nonspherical ellipsoids for pore characterization provides a more accurate and easily interpretable depiction of conductance. To quantify the implications of pore asymmetry on conductance, we systematically investigated carbon nanotubes with varying degrees of pore asymmetry as model systems. The conductance through these channels shows surprising effects that would otherwise not be predicted with spherical probes. The results have broad implications not only for the functional annotation of biological ion channels but also for the design of synthetic channel systems for use in areas such as water filtration. Furthermore, we make use of the more accurate characterization of channel pores to refine a physical conductance model to obtain a heuristic estimate for single-channel conductance. The code is freely available, obtainable as pip-installable python package and provided as a web service.
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Affiliation(s)
- David Seiferth
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford, United Kingdom; Structural Bioinformatics and Computational Biochemistry, Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Philip C Biggin
- Structural Bioinformatics and Computational Biochemistry, Department of Biochemistry, University of Oxford, Oxford, United Kingdom.
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Nurrohman N, Almisbahi H, Tocci E, Abulkhair H, Albeirutty M, Othman R, Bamaga O. Enhancement in Heat Transfer Performance of Water Vapor Condensation on Graphene-Coated Copper Surfaces: A Molecular Dynamics Study. NANOMATERIALS (BASEL, SWITZERLAND) 2024; 14:1137. [PMID: 38998742 PMCID: PMC11243593 DOI: 10.3390/nano14131137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2024] [Revised: 06/20/2024] [Accepted: 06/26/2024] [Indexed: 07/14/2024]
Abstract
The condensation of water vapor plays a crucial role in various applications, including combating water scarcity. In this study, by employing molecular dynamics simulations, we delved into the impact of graphene coatings on water vapor condensation on copper surfaces. Unique to this work was the exploration of various levels of graphene coverage and distribution, a facet largely unexplored in prior investigations. The findings demonstrated a notable increase in the rate of water vapor condensation and heat transfer performance as the graphene coverage was reduced. Using graphene coverages of 84%, 68%, and 52%, the numbers of condensed water molecules were 664, 735, and 880 molecules/ns, respectively. One of the most important findings was that when using the same graphene coverage of 68%, the rate of water vapor condensation and heat transfer performance increased as the graphene coating became more distributed. The overall performance of the water condensation correlated well with the energy and vibrational interaction between the graphene and the copper. This phenomenon suggests how a hybrid surface can enhance the nucleation and growth of a droplet, which might be beneficial for tailoring graphene-coated copper surfaces for applications demanding efficient water vapor condensation.
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Affiliation(s)
- Nurrohman Nurrohman
- Department of Mechanical Engineering, King Abdulaziz University, P.O. Box 80204, Jeddah 21589, Saudi Arabia; (H.A.); (R.O.)
| | - Hind Almisbahi
- Department of Information Technology, King Abdulaziz University, P.O. Box 80220, Jeddah 21589, Saudi Arabia
| | - Elena Tocci
- Institute on Membrane Technology (CNR-ITM), Via P. Bucci 17/C, 87036 Rende, Cosenza, Italy;
| | - Hani Abulkhair
- Department of Mechanical Engineering, King Abdulaziz University, P.O. Box 80204, Jeddah 21589, Saudi Arabia; (H.A.); (R.O.)
- Center of Excellence in Desalination Technology, King Abdulaziz University, P.O. Box 80200, Jeddah 21589, Saudi Arabia;
| | - Mohammed Albeirutty
- Department of Mechanical Engineering, King Abdulaziz University, P.O. Box 80204, Jeddah 21589, Saudi Arabia; (H.A.); (R.O.)
- Center of Excellence in Desalination Technology, King Abdulaziz University, P.O. Box 80200, Jeddah 21589, Saudi Arabia;
| | - Ramzi Othman
- Department of Mechanical Engineering, King Abdulaziz University, P.O. Box 80204, Jeddah 21589, Saudi Arabia; (H.A.); (R.O.)
| | - Omar Bamaga
- Center of Excellence in Desalination Technology, King Abdulaziz University, P.O. Box 80200, Jeddah 21589, Saudi Arabia;
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Hennequin T, Manghi M, Noury A, Henn F, Jourdain V, Palmeri J. Influence of the Quantum Capacitance on Electrolyte Conductivity through Carbon Nanotubes. J Phys Chem Lett 2024; 15:2177-2183. [PMID: 38373147 DOI: 10.1021/acs.jpclett.3c03248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2024]
Abstract
In recent experiments, unprecedentedly large values for the conductivity of electrolytes through carbon nanotubes (CNTs) have been measured, possibly owing to flow slip and a high pore surface charge density whose origin remains debated. Here, we model the coupling between the CNT quantum capacitance and the classical electrolyte-filled pore one and study how electrolyte transport is modulated when a gate voltage is applied to the CNT. Our work shows that under certain conditions the quantum capacitance is lower than the pore one due to the finite quasi-1D CNT electronic density of states and therefore controls the CNT surface charge density that dictates the confined electrolyte conductivity. The dependence of the computed surface charge and conductivity on reservoir salt concentration and gate voltage is thus intimately related to the electronic properties of the CNT. This approach provides key insight into why metallic CNTs have larger experimentally measured conductivities than semiconducting ones.
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Affiliation(s)
- Théo Hennequin
- Laboratoire de Physique Théorique (LPT UMR 5152), Université Toulouse III - Paul Sabatier, CNRS, 31062 Toulouse, France
| | - Manoel Manghi
- Laboratoire de Physique Théorique (LPT UMR 5152), Université Toulouse III - Paul Sabatier, CNRS, 31062 Toulouse, France
| | - Adrien Noury
- Laboratoire Charles Coulomb (L2C, UMR 5221), Université de Montpellier, CNRS, 34090 Montpellier, France
| | - François Henn
- Laboratoire Charles Coulomb (L2C, UMR 5221), Université de Montpellier, CNRS, 34090 Montpellier, France
| | - Vincent Jourdain
- Laboratoire Charles Coulomb (L2C, UMR 5221), Université de Montpellier, CNRS, 34090 Montpellier, France
| | - John Palmeri
- Laboratoire Charles Coulomb (L2C, UMR 5221), Université de Montpellier, CNRS, 34090 Montpellier, France
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