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Jackson GL, Kim SA, Jayaraman A, Diallo SO, Mahanthappa MK. Consequences of Convex Nanopore Chemistry on Confined Water Dynamics. J Phys Chem B 2020; 124:1495-1508. [PMID: 32065528 PMCID: PMC7122394 DOI: 10.1021/acs.jpcb.9b10176] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A fundamental understanding of confined water is crucial for developing selective ion transport and water purification membranes, yet the roles of nanopore geometry and functionality on confined water dynamics remain unresolved. We report the synthesis of perdeuterated ionic alkylsulfonate amphiphiles and their water-induced self-assembly into lyotropic liquid crystal (LLC) mesophases with well-defined, convex, sulfonate-lined nanopores. Quasielastic neutron scattering (QENS) measurements demonstrate that the water self-diffusion coefficients within these sulfonate-lined convex nanopores depend on the hydration level and amphiphile counterion identity (H+, K+, NMe4+). The consistency of the observed counterion-dependent water dynamics trends with those of carboxylate LLCs is rationalized on the basis of similarities in the counterion spatial distributions in the water-filled channels, which we deduce from electron density maps derived from small-angle X-ray scattering (SAXS) analyses. These findings indicate that water diffusion is systematically faster in sulfonate-lined nanopores as compared to carboxylate-lined pores due to weaker water interactions with the softer and more hydrophobic-SO3- functionalities. These molecular-level insights into the relationships between convex pore wall chemical functionalities, hydrated counterions, and confined water diffusion may inform future development of new nanoporous media.
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Affiliation(s)
- Grayson L. Jackson
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Ave., Madison, WI 53706
| | - Sung A Kim
- Department of Chemical Engineering & Materials Science, University of Minnesota, 421 Washington Ave, S.E., Minneapolis, MN 55455
| | - Ashish Jayaraman
- Department of Chemical Engineering & Materials Science, University of Minnesota, 421 Washington Ave, S.E., Minneapolis, MN 55455
| | - Souleymane O. Diallo
- Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
| | - Mahesh K. Mahanthappa
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Ave., Madison, WI 53706
- Department of Chemical Engineering & Materials Science, University of Minnesota, 421 Washington Ave, S.E., Minneapolis, MN 55455
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Jackson GL, Mantha S, Kim SA, Diallo SO, Herwig KW, Yethiraj A, Mahanthappa MK. Ion-Specific Confined Water Dynamics in Convex Nanopores of Gemini Surfactant Lyotropic Liquid Crystals. J Phys Chem B 2018; 122:10031-10043. [PMID: 30251848 DOI: 10.1021/acs.jpcb.8b05942] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The impact of pore geometry and functionality on the dynamics of water nanoconfined in porous media are the subject of some debate. We report the synthesis and small-angle X-ray scattering (SAXS) characterization of a series of perdeuterated gemini surfactant lyotropic liquid crystals (LLCs), in which convex, water-filled nanopores of well-defined dimensions are lined with carboxylate functionalities. Quasielastic neutron scattering (QENS) measurements of the translational water dynamics in these dicarboxylate LLC nanopores as functions of the surfactant hydration state and the charge compensating counterion (Na+, K+, NMe4+) reveal that the measured dynamics depend primarily on surfactant hydration, with an unexpected counterion dependence that varies with hydration number. We rationalize these trends in terms of a balance between counterion-water attractions and the nanopore volume excluded by the counterions. On the basis of electron density maps derived from SAXS analyses of these LLCs, we directly show that the volume excluded by the counterions depends on both their size and spatial distribution in the water-filled channels. The translational water dynamics in the convex pores of these LLCs are also slower than those reported in the concave pores of AOT reverse micelles, implying that water dynamics also depend on the nanopore curvature.
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Affiliation(s)
- Grayson L Jackson
- Department of Chemistry , University of Wisconsin-Madison , 1101 University Avenue , Madison , Wisconsin 53706 , United States
| | - Sriteja Mantha
- Department of Chemistry , University of Wisconsin-Madison , 1101 University Avenue , Madison , Wisconsin 53706 , United States
| | - Sung A Kim
- Department of Chemical Engineering & Materials Science , University of Minnesota , 421 Washington Avenue, S.E. , Minneapolis , Minnesota 55455 , United States
| | | | | | - Arun Yethiraj
- Department of Chemistry , University of Wisconsin-Madison , 1101 University Avenue , Madison , Wisconsin 53706 , United States
| | - Mahesh K Mahanthappa
- Department of Chemistry , University of Wisconsin-Madison , 1101 University Avenue , Madison , Wisconsin 53706 , United States.,Department of Chemical Engineering & Materials Science , University of Minnesota , 421 Washington Avenue, S.E. , Minneapolis , Minnesota 55455 , United States
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Mantha S, Jackson GL, Mahanthappa MK, Yethiraj A. Counterion-Regulated Dynamics of Water Confined in Lyotropic Liquid Crystalline Morphologies. J Phys Chem B 2018; 122:2408-2413. [PMID: 29397720 DOI: 10.1021/acs.jpcb.7b12034] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The dynamics of confined water is of fundamental and long-standing interest. In technologically important forms of confinement, such as proton-exchange membranes, electrostatic interactions with the confining matrix and counterions play significant roles on the properties of water. There has been recent interest on the dynamics of water confined to the lyotropic liquid crystalline (LLC) morphologies of Gemini dicarboxylate surfactants. These systems are exciting because the nature of confinement, for example, size and curvature of channels and surface functionality is dictated by the chemistry of the self-assembling surfactant molecules. Quasielastic neutron scattering experiments have shown an interesting dependence of the water self-diffusion constant, Dα, on the identity (denoted α) of the counterion: at high hydration, the magnitude of the water self-diffusion constant is in the order DTMA < DNa < DK, where TMA, Na, and K refer to tetramethyl ammonium, sodium, and potassium counterions, respectively. This sequence is similar to what is seen in bulk electrolyte solutions. At low hydrations, however, the order of water self-diffusion is different, that is, DNa < DTMA < DK. In this work, we present molecular dynamics simulations for the dynamics of water in the LLC phases of dicarboxylate Gemini surfactants. The simulations reproduce the trends seen in experiments. From an analysis of the trajectories, we hypothesize that two competing factors play a role: the volume accessible to the water molecules and the correlations between the water and the counterion. The excluded volume effect is the largest with TMA+, and the electrostatic correlation is the strongest with Na+. The observed trend is a result of which of these two effects is dominant at a given water to surfactant ratio.
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Affiliation(s)
- Sriteja Mantha
- Department of Chemistry, University of Wisconsin , Madison, Wisconsin 53706, United States
| | - Grayson L Jackson
- Department of Chemistry, University of Wisconsin , Madison, Wisconsin 53706, United States
| | - Mahesh K Mahanthappa
- Department of Chemical Engineering and Materials Science, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Arun Yethiraj
- Department of Chemistry, University of Wisconsin , Madison, Wisconsin 53706, United States
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Martin DR, Forsmo JE, Matyushov DV. Complex Dynamics of Water in Protein Confinement. J Phys Chem B 2017; 122:3418-3425. [PMID: 29206460 DOI: 10.1021/acs.jpcb.7b10448] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This paper studies single-molecule and collective dynamics of water confined in protein powders by means of molecular dynamics simulations. The single-particle dynamics show a modest retardation compared to the bulk but become highly stretched in the powder, with the stretching exponent of ≃0.2. The collective dynamics of the total water dipole are affected by intermolecular correlations inside water and by cross-correlations between the water and the protein. The dielectric spectrum of water in the powder has two nearly equal-amplitude peaks: a Debye peak with ≃16 ps relaxation time and a highly stretched peak with the relaxation time of ≃13 ns and a stretching exponent of ≃0.12. The slower relaxation component is not seen in the single-molecule correlation functions and can be assigned to elastic protein motions displacing water in the powder. The loss spectrum of the intermediate scattering function reported by neutron-scattering experiments is also highly stretched, with the high-frequency wing scaling according to a power law. Translational dynamics can become much slower in the powder than in the bulk but are overshadowed by the rotational loss in the overall loss spectrum of neutron scattering.
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Affiliation(s)
| | - James E Forsmo
- College of Engineering , Georgia Institute of Technology , 225 North Avenue , Atlanta , Georgia 30332 , United States
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McDaniel JG, Mantha S, Yethiraj A. Dynamics of Water in Gemini Surfactant-Based Lyotropic Liquid Crystals. J Phys Chem B 2016; 120:10860-10868. [PMID: 27671427 DOI: 10.1021/acs.jpcb.6b08087] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The dynamics of water confined to nanometer-sized domains is important in a variety of applications ranging from proton exchange membranes to crowding effects in biophysics. In this work, we study the dynamics of water in gemini surfactant-based lyotropic liquid crystals (LLCs) using molecular dynamics simulations. These systems have well characterized morphologies, for example, hexagonal, gyroid, and lamellar, and the surfaces of the confining regions can be controlled by modifying the headgroup of the surfactants. This allows one to study the effect of topology, functionalization, and interfacial curvature on the dynamics of confined water. Through analysis of the translational diffusion and rotational relaxation, we conclude that the hydration level and resulting confinement length scale is the predominate determiner of the rates of water dynamics, and other effects, namely, surface functionality and curvature, are largely secondary. This novel analysis of the water dynamics in these LLC systems provides an important comparison for previous studies of water dynamics in lipid bilayers and reverse micelles.
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Affiliation(s)
- Jesse G McDaniel
- Department of Chemistry, University of Wisconsin , Madison, Wisconsin 53706, United States
| | - Sriteja Mantha
- Department of Chemistry, University of Wisconsin , Madison, Wisconsin 53706, United States
| | - Arun Yethiraj
- Department of Chemistry, University of Wisconsin , Madison, Wisconsin 53706, United States
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Marchese N, Cannuli A, Caccamo MT, Pace C. New generation non-stationary portable neutron generators for biophysical applications of Neutron Activation Analysis. Biochim Biophys Acta Gen Subj 2016; 1861:3661-3670. [PMID: 27212689 DOI: 10.1016/j.bbagen.2016.05.023] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Revised: 05/12/2016] [Accepted: 05/15/2016] [Indexed: 10/21/2022]
Abstract
BACKGROUND Neutron sources are increasingly employed in a wide range of research fields. For some specific purposes an alternative to existing large-scale neutron scattering facilities, can be offered by the new generation of portable neutron devices. SCOPE OF REVIEW This review reports an overview for such recently available neutron generators mainly addressed to biophysics applications with specific reference to portable non-stationary neutron generators applied in Neutron Activation Analysis (NAA). MAJOR CONCLUSIONS The review reports a description of a typical portable neutron generator set-up addressed to biophysics applications. GENERAL SIGNIFICANCE New generation portable neutron devices, for some specific applications, can constitute an alternative to existing large-scale neutron scattering facilities. Deuterium-Deuterium pulsed neutron sources able to generate 2.5MeV neutrons, with a neutron yield of 1.0×106n/s, a pulse rate of 250Hz to 20kHz and a duty factor varying from 5% to 100%, when combined with solid-state photon detectors, show that this kind of compact devices allow rapid and user-friendly elemental analysis. "This article is part of a Special Issue entitled "Science for Life" Guest Editor: Dr. Austen Angell, Dr. Salvatore Magazù and Dr. Federica Migliardo".
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Affiliation(s)
- N Marchese
- DIMES Dipartimento di Ingegneria Informatica, Modellistica, Elettronica e Sistemistica, Università della Calabria, Via P. Bucci, Arcavacata di Rende, Cosenza, Italy
| | - A Cannuli
- Dipartimento di Scienze Matematiche e Informatiche, Scienze Fisiche e Scienze della Terra, Università di Messina, Viale F. Stagno D'Alcontres, S. Agata, Messina, Italy
| | - M T Caccamo
- Dipartimento di Scienze Matematiche e Informatiche, Scienze Fisiche e Scienze della Terra, Università di Messina, Viale F. Stagno D'Alcontres, S. Agata, Messina, Italy
| | - C Pace
- DIMES Dipartimento di Ingegneria Informatica, Modellistica, Elettronica e Sistemistica, Università della Calabria, Via P. Bucci, Arcavacata di Rende, Cosenza, Italy
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