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Becker M, Loche P, Rezaei M, Wolde-Kidan A, Uematsu Y, Netz RR, Bonthuis DJ. Multiscale Modeling of Aqueous Electric Double Layers. Chem Rev 2024; 124:1-26. [PMID: 38118062 PMCID: PMC10785765 DOI: 10.1021/acs.chemrev.3c00307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2023] [Revised: 11/17/2023] [Accepted: 11/30/2023] [Indexed: 12/22/2023]
Abstract
From the stability of colloidal suspensions to the charging of electrodes, electric double layers play a pivotal role in aqueous systems. The interactions between interfaces, water molecules, ions and other solutes making up the electrical double layer span length scales from Ångströms to micrometers and are notoriously complex. Therefore, explaining experimental observations in terms of the double layer's molecular structure has been a long-standing challenge in physical chemistry, yet recent advances in simulations techniques and computational power have led to tremendous progress. In particular, the past decades have seen the development of a multiscale theoretical framework based on the combination of quantum density functional theory, force-field based simulations and continuum theory. In this Review, we discuss these theoretical developments and make quantitative comparisons to experimental results from, among other techniques, sum-frequency generation, atomic-force microscopy, and electrokinetics. Starting from the vapor/water interface, we treat a range of qualitatively different types of surfaces, varying from soft to solid, from hydrophilic to hydrophobic, and from charged to uncharged.
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Affiliation(s)
| | - Philip Loche
- Fachbereich
Physik, Freie Universität Berlin, 14195 Berlin, Germany
- Laboratory
of Computational Science and Modeling, IMX, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Majid Rezaei
- Fachbereich
Physik, Freie Universität Berlin, 14195 Berlin, Germany
- Institute
of Theoretical Chemistry, Ulm University, 89081 Ulm, Germany
| | | | - Yuki Uematsu
- Department
of Physics and Information Technology, Kyushu
Institute of Technology, 820-8502 Iizuka, Japan
- PRESTO,
Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Roland R. Netz
- Fachbereich
Physik, Freie Universität Berlin, 14195 Berlin, Germany
| | - Douwe Jan Bonthuis
- Institute
of Theoretical and Computational Physics, Graz University of Technology, 8010 Graz, Austria
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2
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Seal A, Tiwari U, Gupta A, Govind Rajan A. Incorporating ion-specific van der Waals and soft repulsive interactions in the Poisson-Boltzmann theory of electrical double layers. Phys Chem Chem Phys 2023; 25:21708-21722. [PMID: 37551893 DOI: 10.1039/d3cp00745f] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/09/2023]
Abstract
Electrical double layers (EDLs) arise when an electrolyte is in contact with a charged surface, and are encountered in several application areas including batteries, supercapacitors, electrocatalytic reactors, and colloids. Over the last century, the development of Poisson-Boltzmann (PB) models and their modified versions have provided significant physical insight into the structure and dynamics of the EDL. Incorporation of physics such as finite-ion-size effects, dielectric decrement, and ion-ion correlations has made such models increasingly accurate when compared to more computationally expensive approaches such as molecular simulations and classical density functional theory. However, a prominent knowledge gap has been the exclusion of van der Waals (vdW) and soft repulsive interactions in modified PB models. Although short-ranged as compared to electrostatic interactions, we show here that vdW and soft repulsive interactions can play an important role in determining the structure of the EDL via the formation of a Stern layer and in modulating the differential capacitance of an electrode in an electrolyte. To this end, we incorporate ion-ion and wall-ion vdW attraction and soft repulsion via a 12-6 Lennard-Jones (LJ) potential, resulting in a modified PB-LJ approach. The wall-ion LJ interactions were found to have a significant effect on the electrical potential and concentration profiles, especially close to the wall. However, ion-ion LJ interactions do not affect the EDL structure at low bulk ion concentrations (<1 M). We also derive dimensionless numbers to quantify the impact of ion-ion and wall-ion LJ interactions on the EDL. Furthermore, in the pursuit of capturing ion-specific effects, we apply our model by considering various ions such as Na, K+, Mg2+, Cl-, and SO42-. We observe how varying parameters such as the electrolyte concentration and electrode potential affect the structure of the EDL due to the competition between ion-specific LJ and electrostatic interactions. Lastly, we show that the inclusion of vdW and soft repulsion interactions, as well as hydration effects, leads to a better qualitative agreement of the PB models with experimental double-layer differential capacitance data. Overall, the modified PB-LJ approach presented herein will lead to more accurate theoretical descriptions of EDLs in various application areas.
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Affiliation(s)
- Aniruddha Seal
- School of Chemical Sciences, National Institute of Science Education and Research Bhubaneswar, Homi Bhabha National Institute, Khurda, Odisha 752050, India
- Department of Chemical Engineering, Indian Institute of Science, Bengaluru, Karnataka 560012, India.
| | - Utkarsh Tiwari
- Department of Chemical Engineering, Birla Institute of Technology and Science Pilani, K K Birla Goa Campus, Zuarinagar, Goa 403726, India
- Department of Chemical Engineering, Indian Institute of Science, Bengaluru, Karnataka 560012, India.
| | - Ankur Gupta
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, USA
| | - Ananth Govind Rajan
- Department of Chemical Engineering, Indian Institute of Science, Bengaluru, Karnataka 560012, India.
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3
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Gravelle S, Haber-Pohlmeier S, Mattea C, Stapf S, Holm C, Schlaich A. NMR Investigation of Water in Salt Crusts: Insights from Experiments and Molecular Simulations. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023. [PMID: 37207369 DOI: 10.1021/acs.langmuir.3c00036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The evaporation of water from bare soil is often accompanied by the formation of a layer of crystallized salt, a process that must be understood in order to address the issue of soil salinization. Here, we use nuclear magnetic relaxation dispersion measurements to better understand the dynamic properties of water within two types of salt crusts: sodium chloride (NaCl) and sodium sulfate (Na2SO4). Our experimental results display a stronger dispersion of the relaxation time T1 with frequency for the case of sodium sulfate as compared to sodium chloride salt crusts. To gain insight into these results, we perform molecular dynamics simulations of salt solutions confined within slit nanopores made of either NaCl or Na2SO4. We find a strong dependence of the value of the relaxation time T1 on pore size and salt concentration. Our simulations reveal the complex interplay between the adsorption of ions at the solid surface, the structure of water near the interface, and the dispersion of T1 at low frequency, which we attribute to adsorption-desorption events.
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Affiliation(s)
- Simon Gravelle
- Institute for Computational Physics, University of Stuttgart, D-70569 Stuttgart, Germany
| | - Sabina Haber-Pohlmeier
- Institut für Wasser und Umweltsystemmodellierung, University of Stuttgart, D-70569 Stuttgart, Germany
| | - Carlos Mattea
- Institute of Physics, Technische Universität Ilmenau, Ilmenau 98693, Germany
| | - Siegfried Stapf
- Institute of Physics, Technische Universität Ilmenau, Ilmenau 98693, Germany
| | - Christian Holm
- Institute for Computational Physics, University of Stuttgart, D-70569 Stuttgart, Germany
| | - Alexander Schlaich
- Institute for Computational Physics, University of Stuttgart, D-70569 Stuttgart, Germany
- Stuttgart Center for Simulation Science (SC SimTech), University of Stuttgart, 70569 Stuttgart, Germany
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4
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Tamagawa H, Nakahata T, Sugimori R, Delalande B, Mulembo T. The Membrane Potential Has a Primary Key Equation. Acta Biotheor 2023; 71:15. [PMID: 37148457 DOI: 10.1007/s10441-023-09467-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 04/17/2023] [Indexed: 05/08/2023]
Abstract
It is common to say that the origin of the membrane potential is attributed to transmembrane ion transport, but it is theoretically possible to explain its generation by the mechanism of ion adsorption. It has been previously suggested that the ion adsorption mechanism even leads to potential formulae identical to the famous Nernst equation or the Goldman-Hodgkin-Katz equation. Our further analysis, presented in this paper, indicates that the potential formula based on the ion adsorption mechanism leads to an equation that is a function of the surface charge density of the material and the surface potential of the material. Furthermore, we have confirmed that the equation holds in all the different experimental systems that we have studied. This equation appears to be a key equation that governs the characteristics of the membrane potential in all systems.
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Affiliation(s)
- Hirohisa Tamagawa
- Department of Mechanical Engineering, Faculty of Engineering, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan.
| | - Toi Nakahata
- Department of Mechanical Engineering, Faculty of Engineering, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan
| | - Ren Sugimori
- Department of Mechanical Engineering, Faculty of Engineering, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan
| | | | - Titus Mulembo
- Mechatronic Engineering Department, Dedan Kimathi University of Technology DEKUT, Nyeri, Kenya
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5
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Becker MR, Loche P, Netz RR. Electrokinetic, electrochemical, and electrostatic surface potentials of the pristine water liquid-vapor interface. J Chem Phys 2022; 157:240902. [PMID: 36586978 DOI: 10.1063/5.0127869] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
Although conceptually simple, the air-water interface displays rich behavior and is subject to intense experimental and theoretical investigations. Different definitions of the electrostatic surface potential as well as different calculation methods, each relevant for distinct experimental scenarios, lead to widely varying potential magnitudes and sometimes even different signs. Based on quantum-chemical density-functional-theory molecular dynamics (DFT-MD) simulations, different surface potentials are evaluated and compared to force-field (FF) MD simulations. As well explained in the literature, the laterally averaged electrostatic surface potential, accessible to electron holography, is dominated by the trace of the water molecular quadrupole moment, and using DFT-MD amounts to +4.35 V inside the water phase, very different from results obtained with FF water models which yield negative values of the order of -0.4 to -0.6 V. Thus, when predicting potentials within water molecules, as relevant for photoelectron spectroscopy and non-linear interface-specific spectroscopy, DFT simulations should be used. The electrochemical surface potential, relevant for ion transfer reactions and ion surface adsorption, is much smaller, less than 200 mV in magnitude, and depends specifically on the ion radius. Charge transfer between interfacial water molecules leads to a sizable surface potential as well. However, when probing electrokinetics by explicitly applying a lateral electric field in DFT-MD simulations, the electrokinetic ζ-potential turns out to be negligible, in agreement with predictions using continuous hydrodynamic models. Thus, interfacial polarization charges from intermolecular charge transfer do not lead to significant electrokinetic mobility at the pristine vapor-liquid water interface, even assuming these transfer charges are mobile in an external electric field.
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Affiliation(s)
| | - Philip Loche
- Fachbereich Physik, Freie Universität Berlin, 14195 Berlin, Germany
| | - Roland R Netz
- Fachbereich Physik, Freie Universität Berlin, 14195 Berlin, Germany
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6
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Nguyen MT, Biriukov D, Tempra C, Baxova K, Martinez-Seara H, Evci H, Singh V, Šachl R, Hof M, Jungwirth P, Javanainen M, Vazdar M. Ionic Strength and Solution Composition Dictate the Adsorption of Cell-Penetrating Peptides onto Phosphatidylcholine Membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:11284-11295. [PMID: 36083171 PMCID: PMC9494944 DOI: 10.1021/acs.langmuir.2c01435] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 07/29/2022] [Indexed: 06/15/2023]
Abstract
Adsorption of arginine-rich positively charged peptides onto neutral zwitterionic phosphocholine (PC) bilayers is a key step in the translocation of those potent cell-penetrating peptides into the cell interior. In the past, we have shown both theoretically and experimentally that polyarginines adsorb to the neutral PC-supported lipid bilayers in contrast to polylysines. However, comparing our results with previous studies showed that the results often do not match even at the qualitative level. The adsorption of arginine-rich peptides onto 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) may qualitatively depend on the actual experimental conditions where binding experiments have been performed. In this work, we systematically studied the adsorption of R9 and K9 peptides onto the POPC bilayer, aided by molecular dynamics (MD) simulations and fluorescence cross-correlation spectroscopy (FCCS) experiments. Using MD simulations, we tested a series of increasing peptide concentrations, in parallel with increasing Na+ and Ca2+ salt concentrations, showing that the apparent strength of adsorption of R9 decreases upon the increase of peptide or salt concentration in the system. The key result from the simulations is that the salt concentrations used experimentally can alter the picture of peptide adsorption qualitatively. Using FCCS experiments with fluorescently labeled R9 and K9, we first demonstrated that the binding of R9 to POPC is tighter by almost 2 orders of magnitude compared to that of K9. Finally, upon the addition of an excess of either Na+ or Ca2+ ions with R9, the total fluorescence correlation signal is lost, which implies the unbinding of R9 from the PC bilayer, in agreement with our predictions from MD simulations.
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Affiliation(s)
- Man Thi
Hong Nguyen
- Institute
of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám. 542/2, CZ-16000 Prague 6, Czech Republic
| | - Denys Biriukov
- Institute
of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám. 542/2, CZ-16000 Prague 6, Czech Republic
| | - Carmelo Tempra
- Institute
of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám. 542/2, CZ-16000 Prague 6, Czech Republic
| | - Katarina Baxova
- Institute
of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám. 542/2, CZ-16000 Prague 6, Czech Republic
| | - Hector Martinez-Seara
- Institute
of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám. 542/2, CZ-16000 Prague 6, Czech Republic
| | - Hüseyin Evci
- J.
Heyrovský Institute of Physical Chemistry of the Czech Academy
of Sciences, Dolejškova
2155/3, CZ-18223 Prague 8, Czech Republic
- Department
of Chemistry, Faculty of Science, University
of South Bohemia in Ceske Budejovice, 370 05 Ceske Budejovice, Czech
Republic
| | - Vandana Singh
- J.
Heyrovský Institute of Physical Chemistry of the Czech Academy
of Sciences, Dolejškova
2155/3, CZ-18223 Prague 8, Czech Republic
- Faculty
of Mathematics and Physics at Charles University, 110 00 Prague, Czech Republic
| | - Radek Šachl
- J.
Heyrovský Institute of Physical Chemistry of the Czech Academy
of Sciences, Dolejškova
2155/3, CZ-18223 Prague 8, Czech Republic
| | - Martin Hof
- J.
Heyrovský Institute of Physical Chemistry of the Czech Academy
of Sciences, Dolejškova
2155/3, CZ-18223 Prague 8, Czech Republic
| | - Pavel Jungwirth
- Institute
of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám. 542/2, CZ-16000 Prague 6, Czech Republic
| | - Matti Javanainen
- Institute
of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám. 542/2, CZ-16000 Prague 6, Czech Republic
- Institute
of Biotechnology, University of Helsinki, FI-00014 University
of Helsinki, Finland
| | - Mario Vazdar
- Institute
of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám. 542/2, CZ-16000 Prague 6, Czech Republic
- Department
of Mathematics, University of Chemistry
and Technology, 166 28 Prague, Czech Republic
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7
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Gravelle S, Holm C, Schlaich A. Transport of thin water films: from thermally activated random walks to hydrodynamics. J Chem Phys 2022; 157:104702. [DOI: 10.1063/5.0099646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Under ambient atmospheric conditions, a thin film of water wets many solid surfaces, including insulators, ice, and salt. The film thickness as well as its transport behavior sensitively depend on the surrounding humidity. Understanding this intricate interplay is of highest relevance for water transport through porous media, particularly in the context of soil salinization induced by evaporation. Here, we use molecular simulations to evaluate the transport properties of thin water films on prototypical salt and soil interfaces, namely NaCl and silica solid surfaces. Our results showtwo distinct regimes for water transport: at low water coverage, the film permeance scales linearly with the adsorbed amount, in agreement with the activated random walk model.For thicker water films, the permeance scales as the adsorbed amount to the power of 3, in line with the Stokes equation. By comparing results obtained for silica and NaCl surfaces, we find that, at low water coverage, water permeance at the silica surface is considerably lower than at the NaCl surface, which we attribute to difference in hydrogen bonding. We also investigate the effect of atomic surface defects on the transport properties. Finally, in the context of water transport through porous material, we determine the humidity-dependent crossover between a vapor dominated and a thin film dominated transport regimes depending on the pore size.
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Affiliation(s)
| | - Christian Holm
- Institute for Computational Physics, University of Stuttgart, Germany
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8
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Bohinc K, Špadina M, Reščič J, Shimokawa N, Spada S. Influence of Charge Lipid Head Group Structures on Electric Double Layer Properties. J Chem Theory Comput 2021; 18:448-460. [PMID: 34937343 PMCID: PMC8757465 DOI: 10.1021/acs.jctc.1c00800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
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In this study we
derived a model for a multicomponent lipid monolayer
in contact with an aqueous solution by means of a generalized classical
density functional theory and Monte Carlo simulations. Some of the
important biological lipid systems were studied as monolayers composed
of head groups with different shapes and charge distributions. Starting
from the free energy of the system, which includes the electrostatic
interactions, additional internal degrees of freedom are included
as positional and orientational entropic contributions to the free
energy functional. The calculus of variation was used to derive Euler–Lagrange
equations, which were solved numerically by the finite element method.
The theory and Monte Carlo simulations predict that there are mainly
two distinct regions of the electric double layer: (1) the interfacial
region, with thickness less than or equal to the length of the fully
stretched conformation of the lipid head group, and (2) the outside
region, which follows the usual screening of the interface. In the
interfacial region, the electric double layer is strongly perturbed,
and electrostatic profiles and ion distributions have functionality
distinct to classical mean-field theories. Based purely on Coulomb
interactions, the theory suggests that the dominant effect on the
lipid head group conformation is from the charge density of the interface
and the structured lipid mole fraction in the monolayer, rather than
the salt concentration in the system.
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Affiliation(s)
- Klemen Bohinc
- Faculty of Health Sciences, University of Ljubljana, SI-1000 Ljubljana, Slovenia
| | - Mario Špadina
- Faculty of Health Sciences, University of Ljubljana, SI-1000 Ljubljana, Slovenia
| | - Jurij Reščič
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, SI-1000 Ljubljana, Slovenia
| | - Naofumi Shimokawa
- Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292, Japan
| | - Simone Spada
- National Institute of Oceanography and Applied Geophysics - OGS, 34010 Trieste, Italy
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