1
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Zhang S, Fang M, He J, Ma L, Miao X, Li P, Yu S, Cai W. How specific ion effects influence the mechanical behaviors of amide macromolecules? A cross-scale study. RSC Adv 2024; 14:25507-25515. [PMID: 39139238 PMCID: PMC11321207 DOI: 10.1039/d4ra04360j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2024] [Accepted: 08/01/2024] [Indexed: 08/15/2024] Open
Abstract
The mechanisms of specific ion effects on the properties of amide macromolecules is essential to understanding the evolution of life. Because most biological macromolecules contain both complex hydrophilic and hydrophobic structures, it is challenging to accurately identify the contributions of molecular structure to macroscopic behaviors. Herein, we investigated the influence of specific ion effects on the mechanical behaviors of poly(N-isopropylacrylamide) and neutral polyacrylamide (i.e., PNIPAM and NPAM), through a cross-scale study that includes single-molecule force spectroscopy, molecular dynamics simulation and macro mechanical method. The results indicate that the molecular conformation can be markedly influenced by the hydrophilicity (or hydrophobicity) of both macromolecule chain and ions. An extended chain conformation can be obtained when the side groups and ions are relatively hydrophilic, which can also increase the elasticity of a macromolecule chain and film materials. The relatively hydrophobic components promote the collapse of macromolecule chains and reduce the molecular elasticity. It is believed that the hydrogen bonding intensity between a macromolecule chain and aquated ions controls the chain conformation and the elasticity of molecules and films. This study is not only helpful for understanding the self-assembly mechanism of organisms but also provides a way to associate the molecular properties with the macroscopic performance of materials.
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Affiliation(s)
- Song Zhang
- Department of Food Science and Engineering, Moutai Institute Renhuai 564502 China
| | - Mengjia Fang
- School of Food Science and Engineering, Hefei University of Technology Hefei Anhui 230009 P.R. China
| | - Junjun He
- Department of Food Science and Engineering, Moutai Institute Renhuai 564502 China
| | - Lina Ma
- Department of Food Science and Engineering, Moutai Institute Renhuai 564502 China
| | - Xiaohe Miao
- Instrumentation and Service Center for Physical Sciences, Westlake University Hangzhou 310024 Zhejiang Province China
| | - Peichuang Li
- Heze Branch, Qilu University of Technology (Shandong Academy of Sciences) Heze 274000 China
| | - Shirui Yu
- Department of Food Science and Engineering, Moutai Institute Renhuai 564502 China
| | - Wanhao Cai
- School of Food Science and Engineering, Hefei University of Technology Hefei Anhui 230009 P.R. China
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2
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Clark JA, Douglas JF. Do Specific Ion Effects on Collective Relaxation Arise from Perturbation of Hydrogen-Bonding Network Structure? J Phys Chem B 2024; 128:6362-6375. [PMID: 38912895 PMCID: PMC11229691 DOI: 10.1021/acs.jpcb.4c02638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2024] [Revised: 06/07/2024] [Accepted: 06/10/2024] [Indexed: 06/25/2024]
Abstract
The change in the transport properties (i.e., water diffusivity, shear viscosity, etc.) when adding salts to water has been used to classify ions as either being chaotropic or kosmotropic, a terminology based on the presumption that this phenomenon arises from respective breakdown or enhancement of the hydrogen-bonding network structure. Recent quasi-elastic neutron scattering measurements of the collective structural relaxation time, τC, in aqueous salt solutions were interpreted as confirming this proposed origin of ion effects on the dynamics of water. However, we find similar changes in τC in the same salt solutions based on molecular dynamics (MD) simulations using a coarse-grained water model in which no hydrogen bonding exists, challenging this conventional interpretation of mobility change resulting from the addition of salts to water. A thorough understanding of specific ion effects should be useful in diverse material manufacturing and biomedical applications, where these effects are prevalent, but poorly understood.
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Affiliation(s)
- Jennifer A. Clark
- Materials Science and Engineering
Division, Material Measurement Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, United States
| | - Jack F. Douglas
- Materials Science and Engineering
Division, Material Measurement Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, United States
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3
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Clark JA, Prabhu VM, Douglas JF. Molecular Dynamics Simulation of the Influence of Temperature and Salt on the Dynamic Hydration Layer in a Model Polyzwitterionic Polymer PAEDAPS. J Phys Chem B 2023; 127:8185-8198. [PMID: 37668318 PMCID: PMC10578162 DOI: 10.1021/acs.jpcb.3c03654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/06/2023]
Abstract
We investigate the hydration of poly(3-[2-(acrylamido) ethyldimethylammonio] propanesulfonate) over a range of temperatures in pure water and with the inclusion of 0.1 mol/L NaCl using atomistic molecular dynamics simulation. Drawing on concepts drawn from the field of glass-forming liquids, we use the Debye-Waller parameter () for describing the water mobility gradient around the polybetaine backbone extending to an overall distance ≈18 Å. The water mobility in this layer is defined through the mean-square water molecule displacement at a time on the order of water's β-relaxation time. The brushlike topology of polybetaines leads to two regions in the dynamic hydration layer. The inner region of ≈10.5 Å is explored by pendant group conformational motions, and the outer region of ≈7.5 Å represents an extended layer of reduced water mobility relative to bulk water. The dynamic hydration layer extends far beyond the static hydration layer, adjacent to the polymer.
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Affiliation(s)
- Jennifer A. Clark
- Materials Science and Engineering Division, Material Measurement Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, United States
| | - Vivek M. Prabhu
- Materials Science and Engineering Division, Material Measurement Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, United States
| | - Jack F. Douglas
- Materials Science and Engineering Division, Material Measurement Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, United States
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4
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Shi R, Cooper AJ, Tanaka H. Impact of hierarchical water dipole orderings on the dynamics of aqueous salt solutions. Nat Commun 2023; 14:4616. [PMID: 37550299 PMCID: PMC10406952 DOI: 10.1038/s41467-023-40278-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Accepted: 07/13/2023] [Indexed: 08/09/2023] Open
Abstract
Ions exhibit highly ion-specific complex behaviours when solvated in water, which remains a mystery despite the fundamental importance of ion solvation in nature, science, and technology. Here we explain these ion-specific properties by the ion-induced hierarchical dipolar, translational, and bond-orientational orderings of ion hydration shell under the competition between ion-water electrostatic interactions and inter-water hydrogen bonding. We first characterise this competition by a new length λHB(q), explaining the ion-specific effects on solution dynamics. Then, by continuously tuning ion size and charge, we find that the bond-orientational order of the ion hydration shell highly develops for specific ion size and charge combinations. This ordering drastically stabilises the hydration shell; its degree changes the water residence time around ions by 11 orders of magnitude for main-group ions. These findings are fundamental to ionic processes in aqueous solutions, providing a physical principle for electrolyte design and application.
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Affiliation(s)
- Rui Shi
- Zhejiang Province Key Laboratory of Quantum Technology and Device, School of Physics, Zhejiang University, Hangzhou, 310027, China.
- Department of Fundamental Engineering, Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8505, Japan.
| | - Anthony J Cooper
- Department of Fundamental Engineering, Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8505, Japan
- Department of Physics, University of California, Santa Barbara, CA, 93106-9530, USA
| | - Hajime Tanaka
- Department of Fundamental Engineering, Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8505, Japan.
- Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8904, Japan.
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5
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Kournopoulos S, Santos MS, Ravipati S, Haslam AJ, Jackson G, Economou IG, Galindo A. The Contribution of the Ion-Ion and Ion-Solvent Interactions in a Molecular Thermodynamic Treatment of Electrolyte Solutions. J Phys Chem B 2022; 126:9821-9839. [PMID: 36395498 PMCID: PMC9720728 DOI: 10.1021/acs.jpcb.2c03915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 08/12/2022] [Indexed: 11/19/2022]
Abstract
Developing molecular equations of state to treat electrolyte solutions is challenging due to the long-range nature of the Coulombic interactions. Seminal approaches commonly used are the mean spherical approximation (MSA) and the Debye-Hückel (DH) theory to account for ion-ion interactions and, often, the Born theory of solvation for ion-solvent interactions. We investigate the accuracy of the MSA and DH approaches using each to calculate the contribution of the ion-ion interactions to the chemical potential of NaCl in water, comparing these with newly computer-generated simulation data; the ion-ion contribution is isolated by selecting an appropriate primitive model with a Lennard-Jones force field to describe the solvent. A study of mixtures with different concentrations and ionic strengths reveals that the calculations from both MSA and DH theories are of similar accuracy, with the MSA approach resulting in marginally better agreement with the simulation data. We also demonstrate that the Born theory provides a good qualitative description of the contribution of the ion-solvent interactions; we employ an explicitly polar water model in these simulations. Quantitative agreement up to moderate salt concentrations and across the relevant range of temperature is achieved by adjusting the Born radius using simulation data of the free energy of solvation. We compute the radial and orientational distribution functions of the systems, thereby providing further insight on the differences observed between the theory and simulation. We thus provide rigorous benchmarks for use of the MSA, DH, and Born theories as perturbation approaches, which will be of value for improving existing models of electrolyte solutions, especially in the context of equations of state.
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Affiliation(s)
- Spiros Kournopoulos
- Department
of Chemical Engineering, Sargent Centre for Process Systems Engineering,
and Institute for Molecular Science and Engineering, Imperial College, London, London SW7 2AZ, United Kingdom
| | - Mirella Simões Santos
- Laboratoire
de Chimie, École Normale Supérieure
de Lyon, 46 Allée d’Italie, 69364 Lyon, France
- Australian
Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Srikanth Ravipati
- Department
of Chemical Engineering, Sargent Centre for Process Systems Engineering,
and Institute for Molecular Science and Engineering, Imperial College, London, London SW7 2AZ, United Kingdom
| | - Andrew J. Haslam
- Department
of Chemical Engineering, Sargent Centre for Process Systems Engineering,
and Institute for Molecular Science and Engineering, Imperial College, London, London SW7 2AZ, United Kingdom
| | - George Jackson
- Department
of Chemical Engineering, Sargent Centre for Process Systems Engineering,
and Institute for Molecular Science and Engineering, Imperial College, London, London SW7 2AZ, United Kingdom
| | - Ioannis G. Economou
- Chemical
Engineering Program, Texas A&M University
at Qatar, Doha 23874, Qatar
| | - Amparo Galindo
- Department
of Chemical Engineering, Sargent Centre for Process Systems Engineering,
and Institute for Molecular Science and Engineering, Imperial College, London, London SW7 2AZ, United Kingdom
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6
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Chremos A, Douglas JF, Basser PJ, Horkay F. Prestressed Composite Polymer Gels as a Model of the Extracellular-Matrix of Cartilage. Gels 2022; 8:707. [PMID: 36354615 PMCID: PMC9689112 DOI: 10.3390/gels8110707] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 10/27/2022] [Accepted: 10/28/2022] [Indexed: 10/15/2023] Open
Abstract
Articular cartilage is a composite hydrogel found in animal and human joints, which exhibits unique load-bearing properties that have been challenging to reproduce in synthetic materials and model in molecular dynamics (MD) simulations. We computationally investigate a composite hydrogel that mimics key functional properties of articular cartilage as a potential biomimetic model to investigate its unique load-bearing properties. Specifically, we find that the emergence of prestress in composite gels derives primarily from the stiffness of the polymer matrix and the asymmetry in the enthalpic interactions of the embedded particles and polymer matrix. Our MD simulations of the development of prestress agree qualitatively with osmotic pressure measurements observed in our model composite hydrogel material.
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Affiliation(s)
- Alexandros Chremos
- Section on Quantitative Imaging and Tissue Sciences, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jack F. Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Peter J. Basser
- Section on Quantitative Imaging and Tissue Sciences, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ferenc Horkay
- Section on Quantitative Imaging and Tissue Sciences, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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7
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Lima MA, Rudd TR, Fernig DG, Yates EA. Phosphorylation and sulfation share a common biosynthetic pathway, but extend biochemical and evolutionary diversity of biological macromolecules in distinct ways. JOURNAL OF THE ROYAL SOCIETY, INTERFACE 2022; 19:20220391. [PMID: 35919982 PMCID: PMC9346353 DOI: 10.1098/rsif.2022.0391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Phosphate and sulfate groups are integral to energy metabolism and introduce negative charges into biological macromolecules. One purpose of such modifications is to elicit precise binding/activation of protein partners. The physico-chemical properties of the two groups, while superficially similar, differ in one important respect—the valency of the central (phosphorus or sulfur) atom. This dictates the distinct properties of their respective esters, di-esters and hence their charges, interactions with metal ions and their solubility. These, in turn, determine the contrasting roles for which each group has evolved in biological systems. Biosynthetic links exist between the two modifications; the sulfate donor 3′-phosphoadenosine-5′-phosphosulfate being formed from adenosine triphosphate (ATP) and adenosine phosphosulfate, while the latter is generated from sulfate anions and ATP. Furthermore, phosphorylation, by a xylosyl kinase (Fam20B, glycosaminoglycan xylosylkinase) of the xylose residue of the tetrasaccharide linker region that connects nascent glycosaminoglycan (GAG) chains to their parent proteoglycans, substantially accelerates their biosynthesis. Following observations that GAG chains can enter the cell nucleus, it is hypothesized that sulfated GAGs could influence events in the nucleus, which would complete a feedback loop uniting the complementary anionic modifications of phosphorylation and sulfation through complex, inter-connected signalling networks and warrants further exploration.
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Affiliation(s)
- M A Lima
- Centre for Glycosciences, Keele University, Keele ST5 5BG, UK.,School of Life Sciences, Keele University, Keele ST5 5BG, UK
| | - T R Rudd
- Analytical and Biological Science Department, National Institute of Biological Standards and Control (NIBSC), Blanche Lane, South Mimms, Potters Bar EN6 3QG, UK.,Department of Biochemistry and Systems Biology, ISMIB, University of Liverpool, Liverpool L69 7ZB, UK
| | - D G Fernig
- Department of Biochemistry and Systems Biology, ISMIB, University of Liverpool, Liverpool L69 7ZB, UK
| | - E A Yates
- School of Life Sciences, Keele University, Keele ST5 5BG, UK.,Department of Biochemistry and Systems Biology, ISMIB, University of Liverpool, Liverpool L69 7ZB, UK
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8
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Lin C, Wei H, Li H, Duan X. Structures of cationic and anionic polyelectrolytes in aqueous solutions: the sign effect. SOFT MATTER 2022; 18:1603-1616. [PMID: 35080232 DOI: 10.1039/d1sm01700d] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
In this study, we use molecular dynamics simulation to explore the structures of anionic and cationic polyelectrolytes in aqueous solutions. We first confirm the significantly stronger solvation effects of single anions compared to cations in water at the fixed ion radii, due to the reversal orientations of asymmetric dipolar H2O molecules around the ions. Based on this, we demonstrate that the solvation discrepancy of cations/anions and electrostatic correlations of ionic species can synergistically cause the nontrivial structural difference between single anionic and cationic polyelectrolytes. The cationic polyelectrolyte shows an extended structure whereas the anionic polyelectrolyte exhibits a collapsed structure, and their structural differences decline with increasing the counterion size. Furthermore, we corroborate that multiple cationic polyelectrolytes or multiple anionic polyelectrolytes can exhibit largely differential molecular architectures in aqueous solutions. In the solvation dominant regime, the polyelectrolyte solutions exhibit uniform structures; whereas, in the electrostatic correlation dominant regime, the polyelectrolyte solutions exhibit heterogeneous structures, in which the likely charged chains microscopically aggregate through counterion condensations. Increasing the intrinsic chain rigidity causes polyelectrolyte extension and hence moderately weakens the inter-chain clustering. Our work highlights the various, unique structures and molecular architectures of polyelectrolytes in solutions caused by the multi-body correlations between polyelectrolytes, counterions and asymmetric dipolar solvent molecules, which provides insights into the fundamental understanding of ion-containing polymers.
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Affiliation(s)
- Chengjiang Lin
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China.
- School of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei 230026, P. R. China
| | - Hao Wei
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China.
| | - Hongfei Li
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China.
- School of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei 230026, P. R. China
| | - Xiaozheng Duan
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China.
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9
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Li L, Sun W, Tong Z, Bo M, Ken Ostrikov K, Huang Y, Sun CQ. Discriminative ionic polarizability of alkali halide solutions: Hydration cells, bond distortion, surface stress, and viscosity. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2021.118062] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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10
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Mohanakumar S, Wiegand S. Towards understanding specific ion effects in aqueous media using thermodiffusion. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2022; 45:10. [PMID: 35106668 PMCID: PMC8807466 DOI: 10.1140/epje/s10189-022-00164-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Accepted: 01/10/2022] [Indexed: 06/14/2023]
Abstract
Specific ion effects play an important role in scientific and technological processes. According to Hofmeister, the influence on the hydrogen bond network depends on the ion and leads to a specific order of the ions. Also thermodiffusion the mass transport caused by a temperature gradient is very sensitive to changes of the hydrogen bond network leading to a ranking according to hydrophilicity of the salt. Hence, we investigate various salt solutions in order to compare with the Hofmeister concept. We have studied three different sodium salts in water as a function of temperature (25-45[Formula: see text]C) and concentration (0.5-5 mol kg[Formula: see text]) using Thermal Diffusion Forced Rayleigh Scattering (TDFRS). The three anions studied, carbonate, acetate and thiocyanate, span the entire range of the Hofmeister series from hydrophilic to hydrophobic. We compare the results with the recent measurements of the corresponding potassium salts to see to what extent the cation changes the thermodiffusion of the salt.
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Affiliation(s)
- Shilpa Mohanakumar
- IBI-4:Biomacromolecular Systems and Processes, Forschungszentrum Jülich GmbH, D-52428, Jülich, Germany
| | - Simone Wiegand
- IBI-4:Biomacromolecular Systems and Processes, Forschungszentrum Jülich GmbH, D-52428, Jülich, Germany.
- Chemistry Department-Physical Chemistry, University Cologne, D-50939, Cologne, Germany.
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11
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Lopez CG, Linders J, Mayer C, Richtering W. Diffusion and Viscosity of Unentangled Polyelectrolytes. Macromolecules 2021. [DOI: 10.1021/acs.macromol.1c01169] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Carlos G. Lopez
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany
| | - Jürgen Linders
- Physical Chemistry and Center for Nanointegration Duisburg-Essen (CeNIDE), University of Duisburg-Essen, 45117 Essen, Germany
| | - Christian Mayer
- Physical Chemistry and Center for Nanointegration Duisburg-Essen (CeNIDE), University of Duisburg-Essen, 45117 Essen, Germany
| | - Walter Richtering
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany
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12
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Horkay F, Chremos A, Douglas JF, Jones R, Lou J, Xia Y. Comparative experimental and computational study of synthetic and natural bottlebrush polyelectrolyte solutions. J Chem Phys 2021; 155:074901. [PMID: 34418934 PMCID: PMC8491617 DOI: 10.1063/5.0061649] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 07/30/2021] [Indexed: 11/14/2022] Open
Abstract
We systematically investigate model synthetic and natural bottlebrush polyelectrolyte solutions through an array of experimental techniques (osmometry and neutron and dynamic light scattering) along with molecular dynamics simulations to characterize and contrast their structures over a wide range of spatial and time scales. In particular, we perform measurements on solutions of aggrecan and the synthetic bottlebrush polymer, poly(sodium acrylate), and simulations of solutions of highly coarse-grained charged bottlebrush molecules having different degrees of side-branch density and inclusion of an explicit solvent and ion hydration effects. While both systems exhibit a general tendency toward supramolecular organization in solution, bottlebrush poly(sodium acrylate) solutions exhibit a distinctive "polyelectrolyte peak" in their structure factor, but no such peak is observed in aggrecan solutions. This qualitative difference in scattering properties, and thus polyelectrolyte solution organization, is attributed to a concerted effect of the bottlebrush polymer topology and the solvation of the polymer backbone and counterions. The coupling of the polyelectrolyte topological structure with the counterion distribution about the charged polymer molecules along with direct polymer segmental hydration makes their solution organization and properties "tunable," a phenomenon that has significant ramifications for biological function and disease as well as for numerous materials applications.
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Affiliation(s)
- Ferenc Horkay
- Section on Quantitative Imaging and Tissue Sciences, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Alexandros Chremos
- Section on Quantitative Imaging and Tissue Sciences, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Jack F. Douglas
- Material Measurement Laboratory, Material Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Ronald Jones
- Material Measurement Laboratory, Material Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Junzhe Lou
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
| | - Yan Xia
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
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13
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Zervoudis NA, Obermeyer AC. The effects of protein charge patterning on complex coacervation. SOFT MATTER 2021; 17:6637-6645. [PMID: 34151335 DOI: 10.1039/d1sm00543j] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The complex coacervation of proteins with other macromolecules has applications in protein encapsulation and delivery and for determining the function of cellular coacervates. Theoretical or empirical predictions for protein coacervates would enable the design of these coacervates with tunable and predictable structure-function relationships; unfortunately, no such theories exist. To help establish predictive models, the impact of protein-specific parameters on complex coacervation were probed in this study. The complex coacervation of sequence-specific, polypeptide-tagged, GFP variants and a strong synthetic polyelectrolyte was used to evaluate the effects of protein charge patterning on phase behavior. Phase portraits for the protein coacervates demonstrated that charge patterning dictates the protein's binodal phase boundary. Protein concentrations over 100 mg mL-1 were achieved in the coacervate phase, with concentrations dependent on the tag polypeptide sequence covalently attached to the globular protein domain. In addition to shifting the binodal phase boundary, polypeptide charge patterning provided entropic advantages over isotropically patterned proteins. Together, these results show that modest changes of only a few amino acids in the tag polypeptide sequence alter the coacervation thermodynamics and can be used to tune the phase behavior of polypeptides or proteins of interest.
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Affiliation(s)
- Nicholas A Zervoudis
- Department of Chemical Engineering, Columbia University, New York, NY 10027, USA.
| | - Allie C Obermeyer
- Department of Chemical Engineering, Columbia University, New York, NY 10027, USA.
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14
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Mohanakumar S, Luettmer-Strathmann J, Wiegand S. Thermodiffusion of aqueous solutions of various potassium salts. J Chem Phys 2021; 154:084506. [DOI: 10.1063/5.0038039] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Affiliation(s)
- Shilpa Mohanakumar
- IBI-4: Biomacromolecular Systems and Processes, Forschungszentrum Jülich GmbH, D-52428 Jülich, Germany
| | - Jutta Luettmer-Strathmann
- Department of Physics and Department of Chemistry, The University of Akron, Akron, Ohio 44325-4001, USA
| | - Simone Wiegand
- IBI-4: Biomacromolecular Systems and Processes, Forschungszentrum Jülich GmbH, D-52428 Jülich, Germany
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15
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Shen KH, Fan M, Hall LM. Molecular Dynamics Simulations of Ion-Containing Polymers Using Generic Coarse-Grained Models. Macromolecules 2021. [DOI: 10.1021/acs.macromol.0c02557] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Kuan-Hsuan Shen
- William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, Ohio 43210, United States
| | - Mengdi Fan
- William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, Ohio 43210, United States
| | - Lisa M. Hall
- William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, Ohio 43210, United States
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16
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Bhadauriya S, Wang X, Nallapaneni A, Masud A, Wang Z, Lee J, Bockstaller MR, Al-Enizi AM, Camp CH, Stafford CM, Douglas JF, Karim A. Observation of General Entropy-Enthalpy Compensation Effect in the Relaxation of Wrinkled Polymer Nanocomposite Films. NANO LETTERS 2021; 21:1274-1281. [PMID: 33523666 DOI: 10.1021/acs.nanolett.0c02817] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Surface-textured polymer nanocomposite (PNC) films are utilized in many device applications, and therefore understanding the relaxation behavior of such films is important. By extending an in situ wrinkle relaxation method, we observed that the thermal stability of wrinkled PNC films, both above and below the glass transition temperature (Tg), is proportional to a film's nanoparticle (polymer grafted and bare) concentration, with a slope that changes sign at a compensation temperature (Tcomp) that is determined to be in the vicinity of the film's Tg. This provides unambiguous confirmation of entropy-enthalpy compensation (EEC) as a general feature of PNC films, implying that the stability of PNC films changes from being enhanced to becoming diminished by simply passing through this characteristic temperature, a phenomenon having evident practical ramifications. We suggest EEC will also arise in films where residual stresses are associated with the film fabrication process, which is relevant to nanotech device applications.
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Affiliation(s)
- Sonal Bhadauriya
- Department of Polymer Engineering, University of Akron, Akron, Ohio 44325, United States
| | - Xiaoteng Wang
- Department of Polymer Engineering, University of Akron, Akron, Ohio 44325, United States
| | - Asritha Nallapaneni
- Department of Polymer Engineering, University of Akron, Akron, Ohio 44325, United States
| | - Ali Masud
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas 77204, United States
| | - Zongyu Wang
- Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Jaejun Lee
- Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Michael R Bockstaller
- Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Abdullah M Al-Enizi
- Department of Chemistry, College of Science, King Saud University, PO Box 2455, Riyadh 11451, Saudi Arabia
| | - Charles H Camp
- Biosystems and Biomaterials Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Christopher M Stafford
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Jack F Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Alamgir Karim
- Department of Polymer Engineering, University of Akron, Akron, Ohio 44325, United States
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas 77204, United States
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17
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Ramis R, Ortega-Castro J, Vilanova B, Adrover M, Frau J. Unraveling the NaCl Concentration Effect on the First Stages of α-Synuclein Aggregation. Biomacromolecules 2020; 21:5200-5212. [PMID: 33140640 DOI: 10.1021/acs.biomac.0c01292] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Intraneuronal aggregation of the intrinsically disordered protein α-synuclein is at the core of Parkinson's disease and related neurodegenerative disorders. Several reports show that the concentration of salts in the medium heavily affects its aggregation rate and fibril morphology, but a characterization of the individual monomeric conformations underlying these effects is still lacking. In this work, we have applied our α-synuclein-optimized coarse-grained molecular dynamics approach to decipher the structural features of the protein monomer under a range of NaCl concentrations (0.0-1.0 M). The results show that key intramolecular contacts between the terminal domains are lost at intermediate concentrations (leading to extended conformations likely to fibrillate), but recovered at high concentrations (leading to compact conformations likely to evolve toward amorphous aggregates). The pattern of direct interactions of the terminal α-synuclein domains with Na+ and Cl- ions plays a key role in explaining this effect. Our results are consistent with a recent study reporting a fibrillation enhancement at moderate NaCl concentrations but an inhibition at higher concentrations. The present work will contribute to improving our understanding of the structural features of monomeric α-synuclein, determining its NaCl-induced fibrillation propensity and the molecular basis of synucleinopathies, necessary for the future development of disease-halting therapies.
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Affiliation(s)
- Rafael Ramis
- Institut Universitari d'Investigació en Ciències de la Salut (IUNICS), Departament de Química, Universitat de les Illes Balears, 07122 Palma de Mallorca, Spain.,Institut d'Investigació Sanitària Illes Balears (IdISBa), 07020 Palma de Mallorca, Spain
| | - Joaquín Ortega-Castro
- Institut Universitari d'Investigació en Ciències de la Salut (IUNICS), Departament de Química, Universitat de les Illes Balears, 07122 Palma de Mallorca, Spain.,Institut d'Investigació Sanitària Illes Balears (IdISBa), 07020 Palma de Mallorca, Spain
| | - Bartolomé Vilanova
- Institut Universitari d'Investigació en Ciències de la Salut (IUNICS), Departament de Química, Universitat de les Illes Balears, 07122 Palma de Mallorca, Spain.,Institut d'Investigació Sanitària Illes Balears (IdISBa), 07020 Palma de Mallorca, Spain
| | - Miquel Adrover
- Institut Universitari d'Investigació en Ciències de la Salut (IUNICS), Departament de Química, Universitat de les Illes Balears, 07122 Palma de Mallorca, Spain.,Institut d'Investigació Sanitària Illes Balears (IdISBa), 07020 Palma de Mallorca, Spain
| | - Juan Frau
- Institut Universitari d'Investigació en Ciències de la Salut (IUNICS), Departament de Química, Universitat de les Illes Balears, 07122 Palma de Mallorca, Spain.,Institut d'Investigació Sanitària Illes Balears (IdISBa), 07020 Palma de Mallorca, Spain
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18
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Luo P, Zhai Y, Senses E, Mamontov E, Xu G, Z Y, Faraone A. Influence of Kosmotrope and Chaotrope Salts on Water Structural Relaxation. J Phys Chem Lett 2020; 11:8970-8975. [PMID: 33031702 DOI: 10.1021/acs.jpclett.0c02619] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The structural relaxation in water solutions of kosmotrope (structure maker) and chaotrope (structure breaker) salts, namely sodium chloride, potassium chloride, and cesium chloride, were studied through quasielastic neutron scattering measurements. We found that the collective dynamics relaxation time at the structure factor peak obtained using heavy water solutions shows a distinctively different behavior in the kosmotrope as opposed to the chaotrope solutions, increasing with the salt concentration in the former and decreasing in the latter. In both cases the trends are proportional to the concentration dependence of the relative viscosity of the solutions. These results indicate that kosmotropes and chaotropes influence the solution's viscosity by impacting in opposite ways the hydrogen bond network of water, strengthening it in one case and softening it in the other.
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Affiliation(s)
- Peng Luo
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Department of Nuclear, Plasma, and Radiological Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- NIST Center for Neutron Research, National Institute for Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Yanqin Zhai
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Department of Nuclear, Plasma, and Radiological Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- NIST Center for Neutron Research, National Institute for Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Erkan Senses
- Department of Chemical and Biological Engineering, Koç University, Istanbul 34450, Turkey
| | - Eugene Mamontov
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Guangyong Xu
- NIST Center for Neutron Research, National Institute for Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Y Z
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Department of Nuclear, Plasma, and Radiological Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Antonio Faraone
- NIST Center for Neutron Research, National Institute for Standards and Technology, Gaithersburg, Maryland 20899, United States
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19
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Cracchiolo OM, Geremia DK, Corcelli SA, Serrano AL. Hydrogen Bond Exchange and Ca2+ Binding of Aqueous N-Methylacetamide Revealed by 2DIR Spectroscopy. J Phys Chem B 2020; 124:6947-6954. [DOI: 10.1021/acs.jpcb.0c02444] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Olivia M. Cracchiolo
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Danielle K. Geremia
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Steven A. Corcelli
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Arnaldo L. Serrano
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
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20
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Panagiotopoulos AZ. Simulations of activities, solubilities, transport properties, and nucleation rates for aqueous electrolyte solutions. J Chem Phys 2020; 153:010903. [DOI: 10.1063/5.0012102] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
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21
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Chremos A, Horkay F. Disappearance of the polyelectrolyte peak in salt-free solutions. Phys Rev E 2020; 102:012611. [PMID: 32794995 PMCID: PMC8243406 DOI: 10.1103/physreve.102.012611] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Accepted: 07/10/2020] [Indexed: 11/07/2022]
Abstract
We investigate the nature of the polyelectrolyte peak in salt-free solutions by molecular dynamics simulations using a minimal model of polyelectrolyte solutions that includes an explicit solvent and counterions and small angle scattering experiments. It is found that the polyelectrolyte peak progressively disappears as the strength of solvation for the charged species is increased and the scattering profiles start to resemble those of neutral polymer solutions. The disappearance of the polyelectrolyte peak coincides with the emergence of attractive interchain interactions over a wide range of length scales. These findings provide insights into the microscopic origin of the polyelectrolyte peak.
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Affiliation(s)
- Alexandros Chremos
- Section on Quantitative Imaging and Tissue Sciences, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Ferenc Horkay
- Section on Quantitative Imaging and Tissue Sciences, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
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22
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Horkay F, Chremos A, Douglas JF, L. Jones R, Lou J, Xia Y. Systematic investigation of synthetic polyelectrolyte bottlebrush solutions by neutron and dynamic light scattering, osmometry, and molecular dynamics simulation. J Chem Phys 2020; 152:194904. [PMID: 33687251 PMCID: PMC7252672 DOI: 10.1063/5.0007271] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Accepted: 05/03/2020] [Indexed: 01/30/2023] Open
Abstract
There is a great interest in the synthesis and characterization of polyelectrolytes that mimic naturally occurring bottlebrush polyelectrolytes to capitalize on the unique properties of this class of macromolecules. Charged bottlebrush polymers form the protective mucus layer in the lungs, stomach, and orifices of animals and provide osmotic stabilization and lubrication to joints. In the present work, we systematically investigate bottlebrush poly(sodium acrylates) through a combination of measurements of solution properties (osmometry, small-angle neutron scattering, and dynamic light scattering) and molecular dynamics simulations, where the bottlebrush properties are compared in each case to their linear polymer counterparts. These complementary experimental and computational methods probe vastly different length- and timescales, allowing for a comprehensive characterization of the supermolecular structure and dynamics of synthetic polyelectrolyte bottlebrush molecules in solution.
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Affiliation(s)
- Ferenc Horkay
- Section on Quantitative Imaging and Tissue Sciences, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Alexandros Chremos
- Section on Quantitative Imaging and Tissue Sciences, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Jack F. Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Ronald L. Jones
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Junzhe Lou
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
| | - Yan Xia
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
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23
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Gillespie D, Petsev DN, van Swol F. Electric Double Layers with Surface Charge Regulation Using Density Functional Theory. ENTROPY 2020; 22:e22020132. [PMID: 33285907 PMCID: PMC7516541 DOI: 10.3390/e22020132] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 01/17/2020] [Accepted: 01/19/2020] [Indexed: 01/26/2023]
Abstract
Surprisingly, the local structure of electrolyte solutions in electric double layers is primarily determined by the solvent. This is initially unexpected as the solvent is usually a neutral species and not a subject to dominant Coulombic interactions. Part of the solvent dominance in determining the local structure is simply due to the much larger number of solvent molecules in a typical electrolyte solution.The dominant local packing of solvent then creates a space left for the charged species. Our classical density functional theory work demonstrates that the solvent structural effect strongly couples to the surface chemistry, which governs the charge and potential. In this article we address some outstanding questions relating double layer modeling. Firstly, we address the role of ion-ion correlations that go beyond mean field correlations. Secondly we consider the effects of a density dependent dielectric constant which is crucial in the description of a electrolyte-vapor interface.
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Affiliation(s)
- Dirk Gillespie
- Department of Physiology and Biophysics, Rush University Medical Center, Chicago, IL 60612, USA;
| | - Dimiter N. Petsev
- Department of Chemical and Biological Engineering and Center for Micro-Engineered Materials, University of New Mexico, Albuquerque, NM 87131, USA;
| | - Frank van Swol
- Department of Chemical and Biological Engineering and Center for Micro-Engineered Materials, University of New Mexico, Albuquerque, NM 87131, USA;
- Correspondence:
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24
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Misra A, Kozma K, Streb C, Nyman M. Beyond Charge Balance: Counter-Cations in Polyoxometalate Chemistry. Angew Chem Int Ed Engl 2020; 59:596-612. [PMID: 31260159 PMCID: PMC6972580 DOI: 10.1002/anie.201905600] [Citation(s) in RCA: 219] [Impact Index Per Article: 54.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Indexed: 12/13/2022]
Abstract
Polyoxometalates (POMs) are molecular metal-oxide anions applied in energy conversion and storage, manipulation of biomolecules, catalysis, as well as materials design and assembly. Although often overlooked, the interplay of intrinsically anionic POMs with organic and inorganic cations is crucial to control POM self-assembly, stabilization, solubility, and function. Beyond simple alkali metals and ammonium, chemically diverse cations including dendrimers, polyvalent metals, metal complexes, amphiphiles, and alkaloids allow tailoring properties for known applications, and those yet to be discovered. This review provides an overview of fundamental POM-cation interactions in solution, the resulting solid-state compounds, and behavior and properties that emerge from these POM-cation interactions. We will explore how application-inspired research has exploited cation-controlled design to discover new POM materials, which in turn has led to the quest for fundamental understanding of POM-cation interactions.
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Affiliation(s)
- Archismita Misra
- Institute of Inorganic Chemistry IUlm UniversityAlbert-Einstein-Allee 1189081UlmGermany
| | - Karoly Kozma
- Department of ChemistryOregon State UniversityCorvallisOR97331USA
| | - Carsten Streb
- Institute of Inorganic Chemistry IUlm UniversityAlbert-Einstein-Allee 1189081UlmGermany
| | - May Nyman
- Department of ChemistryOregon State UniversityCorvallisOR97331USA
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25
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Zhang M, Wiener CG, Sepulveda-Medina PI, Douglas JF, Vogt BD. Influence of Sodium Salts on the Swelling and Rheology of Hydrophobically Cross-linked Hydrogels Determined by QCM-D. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:16612-16623. [PMID: 31747520 DOI: 10.1021/acs.langmuir.9b03063] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Hydrophobically modified copolymers provide a versatile platform of hydrogel materials for diverse applications, but the influence of salts on the swelling and material properties of this class of hydrogels has not been extensively studied. Here, we investigate model hydrogels with three different sodium salts with anions chosen from the classic Hofmeister series to determine how these counterions influence the swelling and mechanical properties of neutral hydrogels. The gel chosen was based on a statistical copolymer of dimethylacrylamide and 2-(N-ethylperfluorooctane sulfonamido) ethyl acrylate (FOSA). Our measurements utilize a quartz crystal microbalance with dissipation (QCM-D) to quantify both swelling and rheological properties of these gels. We find that a 1 mol/L solution of Na2SO4, corresponding to a kosmotropic anion, leads to nearly a 2.6-fold gel deswelling and correspondingly, the complex modulus increases by an order of magnitude under these solution conditions. In contrast, an initial increase in swelling and then a swelling maximum is observed for a 0.02 mol/L concentration in the case of a chaotropic anion, NaClO4, but the changes in the degree of gel swelling in this system are not directly correlated with changes in the gel shear modulus. The addition of NaBr, an anion salt closer to the middle of the chaotropic to kosmotropic range, leads to hydrogel deswelling where the degree of deswelling and the shear modulus are both nearly independent of salt concentration. Overall, the observed trends are broadly consistent with more kosmotropic ions causing diminished solubility ("salting out") and strongly chaotropic ions causing improved solubility ("salting in"), a trend characteristic of the Hoffmeister series governing the solubility of many proteins and synthetic water-soluble polymers, but trends in the shear stiffness with gel swelling are clearly different from those normally observed in chemically cross-linked gels and are correspondingly difficult to interpret. The salt specificity of swelling and mechanical properties of nonionic hydrogels is important for any potential application in which a wide range of salt concentrations and types are encountered.
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Affiliation(s)
- Mengxue Zhang
- Department of Polymer Engineering , University of Akron , Akron , Ohio 44325 United States
| | - Clinton G Wiener
- Department of Polymer Engineering , University of Akron , Akron , Ohio 44325 United States
| | | | - Jack F Douglas
- Materials Science and Engineering Division , National Institute of Standards and Technology , Gaithersburg , Maryland 20899 United States
| | - Bryan D Vogt
- Department of Chemical Engineering , The Pennsylvania State University , University Park , Pennsylvania 16802 United States
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26
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Acharya S, Nandi UK, Bhattacharyya SM. Comparative Study of Anomalous Size Dependence of Charged and Neutral Solute Diffusion in Water. J Phys Chem B 2019; 123:10275-10285. [PMID: 31697084 DOI: 10.1021/acs.jpcb.9b08023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We present a comparative study of size dependence of diffusion for charged and neutral solutes in water. Although both show nonmonotonicity of the size dependence of diffusion, their nature and origin are quite different. For neutral solutes, the peak position and the value of diffusion at the maximum are both independent of the solute-water interaction. Interestingly, for charged solutes, with an increase in solute-water interaction strength, the peak position shifts to lower solute sizes and with an increase in charge, it shifts to higher solute sizes. The diffusion value at the peak reduces with an increase in both solute-water interaction and solute charge. We show that all these features observed for charged solutes can be understood in terms of the interplay between ionic and nonionic interactions which is definitely absent for neutral solutes. Some of the earlier studies addressing the nonmonotonicity in diffusion did suggest the interplay between the two interactions to be the cause. However, this is the first time we show that such an interplay gives rise to the nonmonotonicity in the potential energy which is a prerequisite for obtaining the nonmonotonicity in the diffusion. Such nonmonotonicity in the potential energy is absent for neutral solutes.
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Affiliation(s)
- Sayantan Acharya
- Polymer Science and Engineering Department , National Chemical Laboratory , Pune 411008 , India.,Academy of Scientific and Innovative Research (AcSIR) , Ghaziabad 201002 , India
| | - Ujjwal K Nandi
- Polymer Science and Engineering Department , National Chemical Laboratory , Pune 411008 , India.,Academy of Scientific and Innovative Research (AcSIR) , Ghaziabad 201002 , India
| | - Sarika Maitra Bhattacharyya
- Polymer Science and Engineering Department , National Chemical Laboratory , Pune 411008 , India.,Academy of Scientific and Innovative Research (AcSIR) , Ghaziabad 201002 , India
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27
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Shinohara Y, Matsumoto R, Thompson MW, Ryu CW, Dmowski W, Iwashita T, Ishikawa D, Baron AQR, Cummings PT, Egami T. Identifying Water-Anion Correlated Motion in Aqueous Solutions through Van Hove Functions. J Phys Chem Lett 2019; 10:7119-7125. [PMID: 31693369 DOI: 10.1021/acs.jpclett.9b02891] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Electrolyte solutions are ubiquitous in materials in daily use and in biological systems. However, the understanding of their molecular and ionic dynamics, particularly those of their correlated motions, are elusive despite extensive experimental, theoretical, and numerical studies. Here we report the real-space observations of the molecular/ionic-correlated dynamics of aqueous salt (NaCl, NaBr, and NaI) solutions using the Van Hove functions obtained by high-resolution inelastic X-ray scattering measurement and molecular dynamics simulation. Our results directly depict the distance-dependent dynamics of aqueous salt solutions on the picosecond time scale and identify the changes in the anion-water correlations. This study demonstrates the capability of the real-space Van Hove function analysis to describe the local correlated dynamics in aqueous salt solutions.
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Affiliation(s)
- Yuya Shinohara
- Materials Science and Technology Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Ray Matsumoto
- Department of Chemical and Biomolecular Engineering , Vanderbilt University , Nashville , Tennessee 37235 , United States
| | - Matthew W Thompson
- Department of Chemical and Biomolecular Engineering , Vanderbilt University , Nashville , Tennessee 37235 , United States
| | - Chae Woo Ryu
- Department of Materials Science and Engineering , University of Tennessee , Knoxville , Tennessee 37996 , United States
| | - Wojciech Dmowski
- Department of Materials Science and Engineering , University of Tennessee , Knoxville , Tennessee 37996 , United States
| | - Takuya Iwashita
- Department of Integrated Science and Technology , Oita University, Dannoharu , Oita 870-1192 , Japan
| | - Daisuke Ishikawa
- JASRI/SPring-8 , Sayo , Hyogo 679-5198 , Japan
- Materials Dynamics Laboratory , RIKEN SPring-8 Center, RIKEN , Sayo , Hyogo 679-5148 , Japan
| | - Alfred Q R Baron
- Materials Dynamics Laboratory , RIKEN SPring-8 Center, RIKEN , Sayo , Hyogo 679-5148 , Japan
| | - Peter T Cummings
- Department of Chemical and Biomolecular Engineering , Vanderbilt University , Nashville , Tennessee 37235 , United States
| | - Takeshi Egami
- Materials Science and Technology Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
- Department of Materials Science and Engineering , University of Tennessee , Knoxville , Tennessee 37996 , United States
- Department of Physics and Astronomy , University of Tennessee, Knoxville , Knoxville , Tennessee 37996 , United States
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28
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Seo Y, Shen KH, Brown JR, Hall LM. Role of Solvation on Diffusion of Ions in Diblock Copolymers: Understanding the Molecular Weight Effect through Modeling. J Am Chem Soc 2019; 141:18455-18466. [PMID: 31674178 DOI: 10.1021/jacs.9b07227] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Youngmi Seo
- William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, 151 West Woodruff Avenue, Columbus, Ohio 43210, United States
| | - Kuan-Hsuan Shen
- William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, 151 West Woodruff Avenue, Columbus, Ohio 43210, United States
| | - Jonathan R. Brown
- William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, 151 West Woodruff Avenue, Columbus, Ohio 43210, United States
| | - Lisa M. Hall
- William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, 151 West Woodruff Avenue, Columbus, Ohio 43210, United States
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29
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Misra A, Kozma K, Streb C, Nyman M. Jenseits von Ladungsausgleich: Gegenkationen in der Polyoxometallat‐Chemie. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201905600] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Archismita Misra
- Anorganische Chemie I Universtität Ulm Albert-Einstein-Allee 11 89081 Ulm Deutschland
| | - Karoly Kozma
- Department of Chemistry Oregon State University Corvallis OR 97331 USA
| | - Carsten Streb
- Anorganische Chemie I Universtität Ulm Albert-Einstein-Allee 11 89081 Ulm Deutschland
| | - May Nyman
- Department of Chemistry Oregon State University Corvallis OR 97331 USA
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30
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Muttathukattil AN, Srinivasan S, Halder A, Reddy G. Role of Guanidinium-Carboxylate Ion Interaction in Enzyme Inhibition with Implications for Drug Design. J Phys Chem B 2019; 123:9302-9311. [DOI: 10.1021/acs.jpcb.9b06130] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Aswathy N. Muttathukattil
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore, Karnataka 560012, India
| | - Sriraksha Srinivasan
- Department of Chemistry, St. Joseph’s College, Bangalore, Karnataka 560027, India
| | - Antarip Halder
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore, Karnataka 560012, India
| | - Govardhan Reddy
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore, Karnataka 560012, India
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31
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Yue S, Panagiotopoulos AZ. Dynamic properties of aqueous electrolyte solutions from non-polarisable, polarisable, and scaled-charge models. Mol Phys 2019. [DOI: 10.1080/00268976.2019.1645901] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Shuwen Yue
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ, USA
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Gregory KP, Webber GB, Wanless EJ, Page AJ. Lewis Strength Determines Specific-Ion Effects in Aqueous and Nonaqueous Solvents. J Phys Chem A 2019; 123:6420-6429. [DOI: 10.1021/acs.jpca.9b04004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Kasimir P. Gregory
- School of Environmental and Life Sciences, The University of Newcastle, Callaghan, New South Wales 2308, Australia
| | - Grant B. Webber
- School of Engineering, The University of Newcastle, Callaghan, New South Wales 2308, Australia
- Priority Research Centre for Advanced Particle Processing and Transport, The University of Newcastle, Callaghan, New South Wales 2308, Australia
| | - Erica J. Wanless
- School of Environmental and Life Sciences, The University of Newcastle, Callaghan, New South Wales 2308, Australia
- Priority Research Centre for Advanced Particle Processing and Transport, The University of Newcastle, Callaghan, New South Wales 2308, Australia
| | - Alister J. Page
- School of Environmental and Life Sciences, The University of Newcastle, Callaghan, New South Wales 2308, Australia
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Sun CQ, Huang Y, Zhang X. Hydration of Hofmeister ions. Adv Colloid Interface Sci 2019; 268:1-24. [PMID: 30921543 DOI: 10.1016/j.cis.2019.03.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2019] [Revised: 03/04/2019] [Accepted: 03/07/2019] [Indexed: 01/08/2023]
Abstract
Water dissolves salt into ions and then hydrates the ions to form an aqueous solution. Hydration of ions deforms the hydrogen bonding network and triggers the solution with what the pure water never shows such as conductivity, molecular diffusivity, thermal stability, surface stress, solubility, and viscosity, having enormous impact to many branches in biochemistry, chemistry, physics, and energy and environmental industry sectors. However, regulations for the solute-solute-solvent interactions are still open for exploration. From the perspective of the screened ionic polarization and O:H-O bond relaxation, this treatise features the recent progress and a perspective in understanding the hydration dynamics of Hofmeister ions in the typical YI, NaX, ZX2, and NaT salt solutions (Y = Li, Na, K, Rb, Cs; X = F, Cl, Br, I; Z = Mg, Ca, Ba, Sr; T = ClO4, NO3, HSO4, SCN). Phonon spectrometric analysis turned out the f(C) number fraction of bonds transition from the mode of deionized water to the hydrating. The linear f(C) ∝ C form features the invariant hydration volume of small cations that are fully-screened by their hydration H2O dipoles. The nonlinear f(C) ∝ 1 - exp.(-C/C0) form describes that the number insufficiency of the ordered hydrating H2O dipoles partially screens the anions. Molecular anions show stronger yet shorter electric field of dipoles. The screened ionic polarization, inter-solute interaction, and O:H-O bond transition unify the solution conductivity, surface stress, viscosity, and critical energies for phase transition.
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Chremos A, Douglas JF. Influence of solvation on the structure of highly charged nanoparticles in salt-free solutions. POLYMER 2019. [DOI: 10.1016/j.polymer.2019.03.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Nieto-Draghi C, Rousseau B. Thermodynamically Consistent Force Field for Coarse-Grained Modeling of Aqueous Electrolyte Solution. J Phys Chem B 2019; 123:2424-2431. [DOI: 10.1021/acs.jpcb.8b11190] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- Carlos Nieto-Draghi
- IFP Energies nouvelles, 1-4 Avenue de Bois Préau, 92852 Rueil-Malmaison, France
| | - Bernard Rousseau
- Laboratoire de Chimie Physique, UMR 8000 CNRS, Université Paris-Sud, 91405 Orsay, France
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36
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Sun CQ. Aqueous charge injection: solvation bonding dynamics, molecular nonbond interactions, and extraordinary solute capabilities. INT REV PHYS CHEM 2018. [DOI: 10.1080/0144235x.2018.1544446] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Chang Q. Sun
- EBEAM, Yangtze Normal University, Chongqing, People's Republic of China
- NOVITAS, EEE, Nanyang Technological University, Singapore, Singapore
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37
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Abstract
There has been significant interest in the tendency of highly charged particles having the same charge to form dynamic clusters in solution, but an accepted theoretical framework that can account for this ubiquitous phenomenon has been slow to develop. The theoretical difficulties are especially great for flexible polyelectrolytes due to the additional complex coupling between the polyelectrolyte chain configurations and the spatial distribution of the ionic species in solution. For highly charged polyelectrolytes, this leads to the formation of a diffuse "polarizable" cloud of counter-ions around these polymers, an effect having significant implications for the function of proteins and other natural occurring polyelectrolytes, as emphasized long ago by Kirkwood and co-workers. To investigate this phenomenon, we perform molecular dynamics simulations of a minimal model of polyelectrolyte solutions that includes an explicit solvent and counter-ions, where the relative affinity of the counter-ions and the polymer for the solvent is tunable through the variation of the relative strength of the dispersion interactions of the polymer and ions. In particular, we find that these dispersion interactions can greatly influence the nature of the association between the polyelectrolyte chains under salt-free conditions. We calculate static and dynamic correlation functions to quantify the equilibrium structure and dynamics of these complex liquids. Based on our coarse-grained model of polyelectrolyte solutions, we identify conditions in which three distinct types of polyelectrolyte association arise. We rationalize these types of polyelectrolyte association based on the impact of the selective solvent affinity on the charge distribution and polymer solvation in these solutions. Our findings demonstrate the essential role of the solvent in the description of the polyelectrolyte solutions, as well as providing a guideline for the development of a more predictive theory of the properties of the thermodynamic and transport properties of these complex fluids.
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Affiliation(s)
- Alexandros Chremos
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
| | - Jack F. Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
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Andreev M, Prabhu VM, Douglas JF, Tirrell M, de Pablo JJ. Complex Coacervation in Polyelectrolytes from a Coarse-Grained Model. ACS Macro Lett 2018; 51. [PMID: 33299652 DOI: 10.1021/acs.macromol.8b00556] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Complex coacervation refers to the formation of distinct liquid phases that arise when polyelectrolytes are mixed under appropriate polymer and salt concentrations. Molecular-level studies of coacervation have been limited. In this work, a coarse-grained model of the polymers and the corresponding counterions is proposed and used to simulate coacervation as a function of polymer length and overall salt concentration. Several sampling methods are used to determine the phase behavior of the underlying polymers. In particular, the results of simulations in different ensembles are shown to be consistent and to reproduce a number of phenomena observed in experiments, including the disruption of complexation by increasing ionic strength or by decreasing molecular weight. The coacervate concentrations determined from phase behavior calculations are then used to examine the rheology of the corresponding materials. By relying on long dynamic simulations, we are able to generate the dynamic response of the material in the form of dynamic moduli as a function of frequency, which are also found to compare favorably with experimental measurements.
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Affiliation(s)
- Marat Andreev
- Institute of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Vivek M Prabhu
- National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Jack F Douglas
- National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Matthew Tirrell
- Institute of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Juan J de Pablo
- Institute of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
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40
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Li L, Srivastava S, Andreev M, Marciel AB, de Pablo JJ, Tirrell MV. Phase Behavior and Salt Partitioning in Polyelectrolyte Complex Coacervates. Macromolecules 2018. [DOI: 10.1021/acs.macromol.8b00238] [Citation(s) in RCA: 178] [Impact Index Per Article: 29.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Lu Li
- Institute for Molecular Engineering, The University of Chicago, Chicago, Illinois 60637, United States
| | - Samanvaya Srivastava
- Institute for Molecular Engineering, The University of Chicago, Chicago, Illinois 60637, United States
- Institute for Molecular Engineering, Argonne National Laboratory, Lemont, Illinois 60439, United States
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - Marat Andreev
- Institute for Molecular Engineering, The University of Chicago, Chicago, Illinois 60637, United States
| | - Amanda B. Marciel
- Institute for Molecular Engineering, The University of Chicago, Chicago, Illinois 60637, United States
- Institute for Molecular Engineering, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Juan J. de Pablo
- Institute for Molecular Engineering, The University of Chicago, Chicago, Illinois 60637, United States
- Institute for Molecular Engineering, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Matthew V. Tirrell
- Institute for Molecular Engineering, The University of Chicago, Chicago, Illinois 60637, United States
- Institute for Molecular Engineering, Argonne National Laboratory, Lemont, Illinois 60439, United States
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41
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Andreev M, de Pablo JJ, Chremos A, Douglas JF. Influence of Ion Solvation on the Properties of Electrolyte Solutions. J Phys Chem B 2018; 122:4029-4034. [DOI: 10.1021/acs.jpcb.8b00518] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Marat Andreev
- Institute of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Juan J. de Pablo
- Institute of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Alexandros Chremos
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Jack F. Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
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42
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Marciel AB, Srivastava S, Tirrell MV. Structure and rheology of polyelectrolyte complex coacervates. SOFT MATTER 2018; 14:2454-2464. [PMID: 29376531 DOI: 10.1039/c7sm02041d] [Citation(s) in RCA: 113] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Scattering investigations of the structure and chain conformations, and the rheological properties of polyelectrolyte complexes (PECs) comprising model polyelectrolytes are presented. The use of charged polypeptides - (poly)-lysine and (poly)-glutamic acid with identical backbones allowed for facile tuning of the system parameters, including chain length, side-chain functionality, and chirality. Systematic studies using small-angle X-ray scattering (SAXS) of liquid PEC coacervates revealed a physical description of these materials as strongly screened semidilute polyelectrolyte solutions comprising oppositely charged chains. At the same time, solid PECs were found to be composed of hydrogen-bonding driven stiff ladder-like structures. While the coacervates behaved akin to semidilute polyelectrolyte solutions upon addition of salt, the solids were largely unaffected by it. Rheology measurements of PEC coacervates revealed a terminal relaxation regime, with an unusual plateauing of the storage modulus at low oscillation frequencies. The plateau may be ascribed to a combination of instrumental limitations and the long-range electrostatic interactions contributing to weak energy storage modes. Excellent superposition of the dynamic moduli was achieved by a time-salt superposition. The shift factors, however, varied more strongly than previously reported with added salt concentration.
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Affiliation(s)
- Amanda B Marciel
- Institute for Molecular Engineering, The University of Chicago, Chicago, IL 60637, USA.
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43
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Brown JR, Seo Y, Hall LM. Ion Correlation Effects in Salt-Doped Block Copolymers. PHYSICAL REVIEW LETTERS 2018; 120:127801. [PMID: 29694088 DOI: 10.1103/physrevlett.120.127801] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Revised: 12/12/2017] [Indexed: 06/08/2023]
Abstract
We apply classical density functional theory to study how salt changes the microphase morphology of diblock copolymers. Polymers are freely jointed and one monomer type favorably interacts with ions, to account for the selective solvation that arises from different dielectric constants of the microphases. By including correlations from liquid state theory of an unbound reference fluid, the theory can treat chain behavior, microphase separation, ion correlations, and preferential solvation, at the same coarse-grained level. We show good agreement with molecular dynamics simulations.
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Affiliation(s)
- Jonathan R Brown
- William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, 151 West Woodruff Avenue, Columbus, Ohio 43210, USA
| | - Youngmi Seo
- William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, 151 West Woodruff Avenue, Columbus, Ohio 43210, USA
| | - Lisa M Hall
- William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, 151 West Woodruff Avenue, Columbus, Ohio 43210, USA
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44
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Chremos A, Douglas JF. The Influence of Polymer and Ion Solvation on the Conformational Properties of Flexible Polyelectrolytes. Gels 2018; 4:gels4010020. [PMID: 30674796 PMCID: PMC6318697 DOI: 10.3390/gels4010020] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Revised: 02/13/2018] [Accepted: 02/28/2018] [Indexed: 11/16/2022] Open
Abstract
The study of the coupling between the conformational properties of a polyelectrolyte chain and the distribution of counter-ions surrounding the chain is important in developing predictive theories for more complex polymer materials, such as polyelectrolyte gels. We investigated the influence of solvent affinity to counter-ions and the polyelectrolyte backbone on the conformational properties of highly charged flexible polymer chains using molecular dynamics simulations that include both ions and an explicit solvent. We find that the solvation of the polyelectrolyte backbone can be achieved by either increasing the solvent affinity for the polyelectrolyte segments or by increasing the solvent affinity for the counter-ions. However, these two mechanisms influence the conformational properties of the polyelectrolyte chain in rather different ways, suggesting the inadequacy of polyelectrolyte solution models that treat the solvent as a continuum medium.
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Affiliation(s)
- Alexandros Chremos
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
| | - Jack F Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
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45
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Horkay F, Douglas JF. Polymer Gels: Basics, Challenges, and Perspectives. ACS SYMPOSIUM SERIES 2018. [DOI: 10.1021/bk-2018-1296.ch001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Ferenc Horkay
- Section on Quantitative Imaging and Tissue Sciences, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, United States
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46
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Chremos A, Douglas JF. Communication: Counter-ion solvation and anomalous low-angle scattering in salt-free polyelectrolyte solutions. J Chem Phys 2017; 147:241103. [PMID: 29289148 PMCID: PMC5839105 DOI: 10.1063/1.5010784] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We investigate the influence of counter-ion solvation on the homogeneity of salt-free polyelectrolyte solutions based on a coarse-grained model that includes an explicit solvent. We show that the solvation of the counter-ions can cause a transformation between a nearly homogeneous to a non-uniform polymer solution, in which there is both a chain clustering and the formation of large charge-free domains, i.e., "voids." The emergence of these heterogeneous structures induced by counter-ion solvation is accompanied by the localization and formation of counter-ion rich domains that are symptomatic of emergent effective long-range attractive interchain interactions.
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Affiliation(s)
- Alexandros Chremos
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
| | - Jack F. Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
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