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Liu YZ, Chen YN, Sun Q. The Dependence of Hydrophobic Interactions on the Shape of Solute Surface. Molecules 2024; 29:2601. [PMID: 38893477 PMCID: PMC11173737 DOI: 10.3390/molecules29112601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2024] [Revised: 05/26/2024] [Accepted: 05/29/2024] [Indexed: 06/21/2024] Open
Abstract
According to our recent studies on hydrophobicity, this work is aimed at understanding the dependence of hydrophobic interactions on the shape of a solute's surface. It has been observed that dissolved solutes primarily affect the structure of interfacial water, which refers to the top layer of water at the interface between the solute and water. As solutes aggregate in a solution, hydrophobic interactions become closely related to the transition of water molecules from the interfacial region to the bulk water. It is inferred that hydrophobic interactions may depend on the shape of the solute surface. To enhance the strength of hydrophobic interactions, the solutes tend to aggregate, thereby minimizing their surface area-to-volume ratio. This also suggests that hydrophobic interactions may exhibit directional characteristics. Moreover, this phenomenon can be supported by calculated potential mean forces (PMFs) using molecular dynamics (MD) simulations, where different surfaces, such as convex, flat, or concave, are associated with a sphere. Furthermore, this concept can be extended to comprehend the molecular packing parameter, commonly utilized in studying the self-assembly behavior of amphiphilic molecules in aqueous solutions.
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Affiliation(s)
| | | | - Qiang Sun
- Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education, The School of Earth and Space Sciences, Peking University, Beijing 100871, China; (Y.-Z.L.); (Y.-N.C.)
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2
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Liao F, Tian Z, Yang X, Yang H, Liu X, Liao H, Duan L. Hydrophobic association: A facile approach to prepare physical cross-linked gelatin hydrogel with desirable thermal stability, flexibility and self-healing ability. Int J Biol Macromol 2024; 262:130058. [PMID: 38340943 DOI: 10.1016/j.ijbiomac.2024.130058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Revised: 02/02/2024] [Accepted: 02/06/2024] [Indexed: 02/12/2024]
Abstract
Methacrylic anhydride was added to 20 % gelatin solution to prepare gelatin methacryloyl (GelMA) but an unexpected gelation process was observed within several minutes. The experimental data revealed that the methacryloyl substitution can increase the hydrophobicity of gelatin and the micellar diameter in solution. Therefore, we speculated that the methacryloyl substitution caused the formation of micellar cross-links based on the hydrophobic residues of gelatin and the methacryloyl groups, thus obtaining the hydrophobic association hydrogels. The thixotropic and tensile experiments confirmed that GelMA hydrogel possessed the features of hydrophobic association hydrogels like self-healing and stretchable abilities. The rheological experiments revealed that the gelation rate and the mechanical strength of the GelMA hydrogels were in direct proportion to the concentration of GelMA and the degree of methacryloyl substitution. GelMA hydrogels possessed desirable thermal stability that it didn't melt after being heated to 90 °C. Furthermore, the MTT assays and calcein AM/PI staining revealed that GelMA hydrogel was biocompatible. These results collectively confirm that the hydrophobic association is a prospective and facile approach to prepare gelatin hydrogel with desirable properties for further application.
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Affiliation(s)
- Fuying Liao
- State Key Laboratory of Resource Insects, College of Sericulture, Textile and Biomass Sciences, Southwest University, Chongqing 400715, PR China
| | - Zhenhua Tian
- College of Bioresources Chemical and Materials Engineering, Shaanxi University of Science & Technology, Xi'an 710021, PR China.
| | - Xiao Yang
- State Key Laboratory of Resource Insects, College of Sericulture, Textile and Biomass Sciences, Southwest University, Chongqing 400715, PR China
| | - Huan Yang
- Shandong Provincial Key Laboratory of Molecular Engineering, School of Chemistry and Chemical Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, PR China
| | - Xin Liu
- State Key Laboratory of Resource Insects, College of Sericulture, Textile and Biomass Sciences, Southwest University, Chongqing 400715, PR China
| | - Hao Liao
- State Key Laboratory of Resource Insects, College of Sericulture, Textile and Biomass Sciences, Southwest University, Chongqing 400715, PR China
| | - Lian Duan
- State Key Laboratory of Resource Insects, College of Sericulture, Textile and Biomass Sciences, Southwest University, Chongqing 400715, PR China.
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3
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Naito H, Sumi T, Koga K. How do water-mediated interactions and osmotic second virial coefficients vary with particle size? Faraday Discuss 2024; 249:440-452. [PMID: 37791511 DOI: 10.1039/d3fd00104k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
We examine quantitatively the solute-size dependences of the effective interactions between nonpolar solutes in water and in a simple liquid. The potential w(r) of mean force and the osmotic second virial coefficients B are calculated with high accuracy from molecular dynamics simulations. As the solute diameter increases from methane's to C60's with the solute-solute and solute-solvent attractive interaction parameters fixed to those for the methane-methane and methane-water interactions, the first minimum of w(r) lowers from -1.1 to -4.7 in units of the thermal energy kT. Correspondingly, the magnitude of B (<0) increases proportional to σα with some power close to 6 or 7, which reinforces the solute-size dependence of B found earlier for a smaller range of σ [H. Naito, R. Okamoto, T. Sumi and K. Koga, J. Chem. Phys., 2022, 156, 221104]. We also demonstrate that the strength of the attractive interactions between solute and solvent molecules can qualitatively change the characteristics of the effective pair interaction between solute particles, both in water and in a simple liquid. If the solute-solvent attractive force is set to be weaker (stronger) than a threshold, the effective interaction becomes increasingly attractive (repulsive) with increasing solute size.
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Affiliation(s)
- Hidefumi Naito
- Department of Chemistry, Faculty of Science, Okayama University, Okayama 700-8530, Japan.
- Research Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan
| | - Tomonari Sumi
- Department of Chemistry, Faculty of Science, Okayama University, Okayama 700-8530, Japan.
- Research Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan
| | - Kenichiro Koga
- Department of Chemistry, Faculty of Science, Okayama University, Okayama 700-8530, Japan.
- Research Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan
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4
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Hosseni A, Ashbaugh HS. Osmotic Force Balance Evaluation of Aqueous Electrolyte Osmotic Pressures and Chemical Potentials. J Chem Theory Comput 2023; 19:8826-8838. [PMID: 37978934 PMCID: PMC10720338 DOI: 10.1021/acs.jctc.3c00982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 10/26/2023] [Accepted: 10/27/2023] [Indexed: 11/19/2023]
Abstract
Concentrated aqueous salt solutions are ubiquitous in problems of biological and environmental relevance. The development of accurate force fields that capture the interactions between dissolved species in solution is crucial to simulating these systems to gain molecular insights into the underlying processes under saline conditions. The osmotic pressure is a relatively simple thermodynamic property connecting the experimental and simulation measurements of the associative properties of the ions in solution. Milner [C. Gillespie and S. T. Milner, Soft Matter, 16, 9816 (2020)] proposed a simulation approach to evaluate the osmotic pressures of salts in solution by applying a restraint potential to the ions alone in solution and determining the resulting pressure required to balance that potential, referred to here as the osmotic force balance. Here, we expand Milner's approach, demonstrating that the chemical potentials of the salts in solution as a function of concentration can be fitted to the concentration profiles determined from simulation, additionally providing an analytical expression for the osmotic pressure. This approach is used to determine the osmotic pressures of 15 alkali halide salts in water from simulations. The cross interactions between cations and anions in solution are subsequently optimized to capture their experimental osmotic pressures.
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Affiliation(s)
- Alireza Hosseni
- Department of Chemical and
Biomolecular Engineering, Tulane University, New Orleans, Louisiana 70118, United States
| | - Henry S. Ashbaugh
- Department of Chemical and
Biomolecular Engineering, Tulane University, New Orleans, Louisiana 70118, United States
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5
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Wang Y, Allen O, Collins E, Ashbaugh HS. Methane at the gas/water interface: Molecular simulations of surface adsorption and second surface virial coefficients. Colloids Surf A Physicochem Eng Asp 2022. [DOI: 10.1016/j.colsurfa.2022.129725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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6
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Sun Q, Fu Y, Wang W. Temperature effects on hydrophobic interactions: Implications for protein unfolding. Chem Phys 2022. [DOI: 10.1016/j.chemphys.2022.111550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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7
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Naito H, Okamoto R, Sumi T, Koga K. Osmotic second virial coefficients for hydrophobic interactions as a function of solute size. J Chem Phys 2022; 156:221104. [PMID: 35705398 DOI: 10.1063/5.0097547] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
To gain quantitative insight into how the overall strength of the hydrophobic interaction varies with the molecular size, we calculate osmotic second virial coefficients B for hydrophobic spherical molecules of different diameters σ in water based on molecular simulation with corrections to the finite-size and finite-concentration effects. It is shown that B (<0) changes by two orders of magnitude greater as σ increases twofold and its solute-size dependence is best fit by a power law B ∝ σα with the exponent α ≃ 6, which contrasts with the cubic power law that the second virial coefficients of gases obey. It is also found that values of B for the solutes in a nonpolar solvent are positive but they obey the same power law as in water. A thermodynamic identity for B derived earlier [K. Koga, V. Holten, and B. Widom, J. Phys. Chem. B 119, 13391 (2015)] indicates that if B is asymptotically proportional to a power of σ, the exponent α must be equal to or greater than 6.
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Affiliation(s)
- Hidefumi Naito
- Department of Chemistry, Faculty of Science, Okayama University, Okayama 700-8530, Japan
| | - Ryuichi Okamoto
- Department of Chemistry, Faculty of Science, Okayama University, Okayama 700-8530, Japan
| | - Tomonari Sumi
- Department of Chemistry, Faculty of Science, Okayama University, Okayama 700-8530, Japan
| | - Kenichiro Koga
- Department of Chemistry, Faculty of Science, Okayama University, Okayama 700-8530, Japan
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8
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Raubenolt BA, Rick SW. Simulation studies of polypeptoids using replica exchange with dynamical scaling and dihedral biasing. J Comput Chem 2022; 43:1229-1236. [PMID: 35543334 DOI: 10.1002/jcc.26887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 03/15/2022] [Accepted: 04/22/2022] [Indexed: 11/06/2022]
Abstract
Polypeptoids differ from polypeptides in that the amide bond can more frequently adopt both cis and trans conformations. The transition between the two conformations requires overcoming a large energy barrier, making it difficult for conventional molecular simulations to adequately visit the cis and trans structures. A replica-exchange method is presented that allows for easy rotations of the amide bond and also an efficient linking to a high temperature replica. The method allows for just three replicas (one at the temperature and Hamiltonian of interest, a second high temperature replica with a biased dihedral potential, and a third connecting them) to overcome the amide bond sampling problem and also enhance sampling for other coordinates. The results indicate that for short peptoid oligomers, the conformations can range from all cis to all trans with an average cis/trans ratio that depends on side chain and potential model.
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Affiliation(s)
- Bryan A Raubenolt
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana, USA
| | - Steven W Rick
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana, USA
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9
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Rick SW. Insights into the Thermal Response of a Poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) Triblock Polymer in Water. J Phys Chem B 2021; 125:2167-2173. [PMID: 33606935 DOI: 10.1021/acs.jpcb.0c11279] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A thermal responsive block copolymer made up of ethylene oxide (EO) and propylene oxide (PO) blocks was simulated with optimized atomistic potentials and enhanced sampling methods over a range of temperatures. The results for the L42 pluronic polymer (EO)4(PO)22(EO)4, which is known to undergo a transition in this temperature range, and the similarly sized (EO)30 polymer, which does not, are compared. The thermal responsive L42 polymers in a dilute solution tend to aggregate, and this tendency gets stronger as temperature increases. The poly(ethylene oxide) polymer shows no such tendency. The aggregation is stabilized by the hydrophobic contact of the propylene oxide methyl groups, which outweighs a small loss in hydrogen bonds between the ether oxygens and water.
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Affiliation(s)
- Steven W Rick
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, United States
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10
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Ashbaugh HS, Bukannan H. Temperature, Pressure, and Concentration Derivatives of Nonpolar Gas Hydration: Impact on the Heat Capacity, Temperature of Maximum Density, and Speed of Sound of Aqueous Mixtures. J Phys Chem B 2020; 124:6924-6942. [PMID: 32692557 DOI: 10.1021/acs.jpcb.0c04035] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The hydrophobic effect is an umbrella term encompassing a number of solvation phenomena associated with solutions of nonpolar species in water, including the following: a meager solubility opposed by entropy at room temperature; large positive hydration heat capacities; positive shifts in the temperature of maximum density of aqueous mixtures; increases in the speed of sound of dilute aqueous mixtures; and negative volumes of association between interacting solutes. Here we present a molecular simulation study of nonpolar gas hydration over the temperature range 273.15-373.15 K and a pressure range -500 to 1000 bar to investigate the interrelationships between distinct hydrophobic phenomena. We develop a new free energy correlation for the solute chemical potentials founded on the Tait equation description of the equation-of-state of liquid water. This analytical correlation is shown to provide a quantitatively accurate description of nonpolar gas hydration over the entire range of thermodynamic state points simulated, with an error of ∼0.02 kBT or lower in the fitted chemical potentials. Our simulations and the correlation accurately reproduce many of the available experimental results for the hydration of the solutes examined here. Moreover, the correlation reproduces the characteristic entropies of hydration, temperature dependence of the hydration heat capacity, perturbations in the temperature of maximum density, and changes in the speed of sound. While negative volumes of association result from pairwise interactions in solution, beyond the limits of our simulations performed at infinite dilution, we discuss how our correlation could be supplemented with second virial coefficient information to expand to finite concentrations. In total, this work demonstrates that many distinct phenomena associated with the hydrophobic effect can be captured within a single thermodynamically consistent correlation for solute hydration free energies.
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Affiliation(s)
- Henry S Ashbaugh
- Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, Louisiana 70118, United States
| | - Hussain Bukannan
- Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, Louisiana 70118, United States
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11
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Gasic AG, Cheung MS. A Tale of Two Desolvation Potentials: An Investigation of Protein Behavior under High Hydrostatic Pressure. J Phys Chem B 2020; 124:1619-1627. [DOI: 10.1021/acs.jpcb.9b10734] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Andrei G. Gasic
- Department of Physics, University of Houston, Houston, Texas 77204, United States
- Center for Theoretical Biological Physics, Rice University, Houston, Texas 77005, United States
| | - Margaret S. Cheung
- Department of Physics, University of Houston, Houston, Texas 77204, United States
- Center for Theoretical Biological Physics, Rice University, Houston, Texas 77005, United States
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12
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Saltzman A, Houser H, Langrehr M, Ashbaugh HS. Nonpolar solute cononsolvency in ethanol/water mixtures – Connections to solvent structure. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2019.111944] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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13
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Barnett JW, Ashbaugh HS. Evaluation of second osmotic virial coefficients from molecular simulation following scaled-particle theory. MOLECULAR SIMULATION 2019. [DOI: 10.1080/08927022.2019.1639698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- J. Wesley Barnett
- Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, LA, USA
| | - Henry S. Ashbaugh
- Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, LA, USA
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14
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Abstract
Hydration-shell vibrational spectroscopy provides an experimental window into solute-induced water structure changes that mediate aqueous folding, binding, and self-assembly. Decomposition of measured Raman and infrared (IR) spectra of aqueous solutions using multivariate curve resolution (MCR) and related methods may be used to obtain solute-correlated spectra revealing solute-induced perturbations of water structure, such as changes in water hydrogen-bond strength, tetrahedral order, and the presence of dangling (non-hydrogen-bonded) OH groups. More generally, vibrational-MCR may be applied to both aqueous and nonaqueous solutions, including multicomponent mixtures, to quantify solvent-mediated interactions between oily, polar, and ionic solutes, in both dilute and crowded fluids. Combining vibrational-MCR with emerging theoretical modeling strategies promises synergetic advances in the predictive understanding of multiscale self-assembly processes of both biological and technological interest.
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Affiliation(s)
- Dor Ben-Amotz
- Department of Chemistry , Purdue University , West Lafayette , Indiana 47907 , United States
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15
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Bilodeau CL, Lau EY, Cramer SM, Garde S. Conformational Equilibria of Multimodal Chromatography Ligands in Water and Bound to Protein Surfaces. J Phys Chem B 2019; 123:4833-4843. [DOI: 10.1021/acs.jpcb.9b01218] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Camille L. Bilodeau
- Howard P. Isermann Department of Chemical and Biological Engineering and Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, 110 Eighth Street, Troy, New York 12180, United States
| | - Edmond Y. Lau
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | - Steven M. Cramer
- Howard P. Isermann Department of Chemical and Biological Engineering and Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, 110 Eighth Street, Troy, New York 12180, United States
| | - Shekhar Garde
- Howard P. Isermann Department of Chemical and Biological Engineering and Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, 110 Eighth Street, Troy, New York 12180, United States
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16
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Chialvo AA, Crisalle OD. On the behavior of the osmotic second virial coefficients of gases in aqueous solutions: Rigorous results, accurate approximations, and experimental evidence. J Chem Phys 2019; 150:124503. [DOI: 10.1063/1.5047525] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Affiliation(s)
| | - Oscar D. Crisalle
- Department of Chemical Engineering, University of Florida, Gainesville, Florida 32611, USA
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17
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Islam N, Flint M, Rick SW. Water hydrogen degrees of freedom and the hydrophobic effect. J Chem Phys 2019; 150:014502. [DOI: 10.1063/1.5053239] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Naeyma Islam
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, USA
| | - Mahalia Flint
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, USA
| | - Steven W. Rick
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, USA
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18
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Okamoto R, Onuki A. Theory of nonionic hydrophobic solutes in mixture solvent: Solvent-mediated interaction and solute-induced phase separation. J Chem Phys 2018; 149:014501. [DOI: 10.1063/1.5037673] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Ryuichi Okamoto
- Research Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan
| | - Akira Onuki
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
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19
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Ashbaugh HS, Barnett JW, Saltzman A, Langrehr M, Houser H. Connections between the Anomalous Volumetric Properties of Alcohols in Aqueous Solution and the Volume of Hydrophobic Association. J Phys Chem B 2018; 122:3242-3250. [PMID: 28968101 DOI: 10.1021/acs.jpcb.7b08728] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The partial molar volumes of alcohols in water exhibit a non-monotonic dependence on concentration at room temperature, initially decreasing with increasing concentration before passing through a minimum and rising to the pure liquid plateau. This anomalous behavior is associated with hydrophobic interactions. We report molecular simulations of short chain alcohols and alkanes in water to examine the volumetric properties of these mixtures at infinite dilution over a range of temperatures. Our simulations find this anomaly disappears at a crossover temperature, above which the solute volume only varies monotonically with concentration. A Voronoi volume analysis of solution configurations finds that solutes in clusters take up less space than individual solutes at low temperature and more space at elevated temperatures. These changes in cluster volumes are subsequently shown to correlate with the derivative of the solute partial molar volume with respect to solute concentration. The changes in solute volume upon nonpolar solute association impact the response of molecular-scale hydrophobic interactions for assembly with increasing pressure.
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Affiliation(s)
- Henry S Ashbaugh
- Department of Chemical and Biomolecular Engineering , Tulane University , New Orleans , Louisiana 70118 , United States
| | - J Wesley Barnett
- Department of Chemical and Biomolecular Engineering , Tulane University , New Orleans , Louisiana 70118 , United States
| | - Alexander Saltzman
- Department of Chemical and Biomolecular Engineering , Tulane University , New Orleans , Louisiana 70118 , United States
| | - Mae Langrehr
- Department of Chemical and Biomolecular Engineering , University of Delaware , Newark , Delaware 19716 , United States
| | - Hayden Houser
- Department of Chemical and Biomolecular Engineering , Tulane University , New Orleans , Louisiana 70118 , United States
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20
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Koga K, Yamamoto N. Hydrophobicity Varying with Temperature, Pressure, and Salt Concentration. J Phys Chem B 2018; 122:3655-3665. [PMID: 29357255 DOI: 10.1021/acs.jpcb.7b12193] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Temperature-, pressure-, and salt-concentration-induced variations in the solubility of small nonpolar solutes in aqueous solution and the corresponding variations in the solvent-induced pair attraction between such solute molecules are investigated. The variations in the solvation free energy of a solute and those in the solvent-induced pair attraction are well reproduced by a mean-field approximation in which the repulsive cores of solute molecules are treated as hard spheres and the mean-field energy of a solute molecule is taken to be the average potential energy that the solute molecule feels in solution. The mechanisms of variation in the solvation free energy and those of variation in the solvent-induced pair potential, with increasing temperature, pressure, and salt concentration, are clarified. Correlations between the solvation free energy and the solvent-induced pair potential at a contact distance in temperature, pressure, and salt concentration variations are near linear in any mode of variation, but the slope of the linear relation is dependent on the mode of variation and is determined by a ratio of the solvation thermodynamic quantities characteristic of each mode of variation.
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Affiliation(s)
- K Koga
- Research Institute for Interdisciplinary Science , Okayama University , Okayama 700-8530 , Japan.,Department of Chemistry, Faculty of Science , Okayama University , Okayama 700-8530 , Japan
| | - N Yamamoto
- Department of Chemistry, Faculty of Science , Okayama University , Okayama 700-8530 , Japan
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21
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Nayar D, van der Vegt NFA. Cosolvent Effects on Polymer Hydration Drive Hydrophobic Collapse. J Phys Chem B 2018; 122:3587-3595. [PMID: 29443520 DOI: 10.1021/acs.jpcb.7b10780] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Water-mediated hydrophobic interactions play an important role in self-assembly processes, aqueous polymer solubility, and protein folding, to name a few. Cosolvents affect these interactions; however, the implications for hydrophobic polymer collapse and protein folding equilibria are not well-understood. This study examines cosolvent effects on the hydrophobic collapse equilibrium of a generic 32-mer hydrophobic polymer in urea, trimethylamine- N-oxide (TMAO), and acetone aqueous solutions using molecular dynamics simulations. Our results unveil a remarkable cosolvent-concentration-dependent behavior. Urea, TMAO, and acetone all shift the equilibrium toward collapsed structures below 2 M cosolvent concentration and, in turn, to unfolded structures at higher cosolvent concentrations, irrespective of the differences in cosolvent chemistry and the nature of cosolvent-water interactions. We find that weakly attractive polymer-water van der Waals interactions oppose polymer collapse in pure water, corroborating related observations reviewed by Ben-Amotz ( Annu. Rev. Phys. Chem. 2016, 67, 617-638). The cosolvents studied in the present work adsorb at the polymer/water interface and expel water molecules into the bulk, thereby effectively removing the dehydration energy penalty that opposes polymer collapse in pure water. At low cosolvent concentrations, this leads to cosolvent-induced stabilization of collapsed polymer structures. Only at sufficiently high cosolvent concentrations, polymer-cosolvent interactions favor polymer unfolding.
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Affiliation(s)
- Divya Nayar
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Center of Smart Interfaces , Technische Universität Darmstadt , Alarich-Weiss-Strasse 10 , 64287 , Darmstadt , Germany
| | - Nico F A van der Vegt
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Center of Smart Interfaces , Technische Universität Darmstadt , Alarich-Weiss-Strasse 10 , 64287 , Darmstadt , Germany
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22
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Tang D, Delpo C, Blackmon O, Ashbaugh HS. Note: Second osmotic virial coefficients of short alkanes and their alcohol counterparts in water as a function of temperature. J Chem Phys 2018; 148:016101. [DOI: 10.1063/1.5008573] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Affiliation(s)
- Du Tang
- Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, Louisiana 70118, USA
| | - Courtney Delpo
- Department of Chemistry, Ursinus College, Collegeville, Pennsylvania 19426, USA
| | - Odella Blackmon
- Department of Chemistry, William Carey University, Hattiesburg, Mississippi 39401, USA
| | - Henry S. Ashbaugh
- Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, Louisiana 70118, USA
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Ashbaugh HS, Wesley Barnett J, Saltzman A, Langrehr ME, Houser H. Communication: Stiffening of dilute alcohol and alkane mixtures with water. J Chem Phys 2017; 145:201102. [PMID: 27908098 DOI: 10.1063/1.4971205] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We probe the anomalous compressibilities of dilute mixtures of alcohols and alkane gases in water using molecular simulations. The response to increasing solute concentration depends sensitively on temperature, with the compressibility decreasing upon solute addition at low temperatures and increasing at elevated temperatures. The thermodynamic origin of stiffening is directly tied to the solute's partial compressibility, which is negative at low temperatures and rises above water's compressibility with increasing temperature. Hydration shell waters concurrently tilt towards clathrate-like structures at low temperatures that fade with heating. Kirkwood-Buff theory traces the solute's partial compressibility to changes in the solute-water association volume upon heating and incongruous packing of waters at the boundary between the more structured hydration shell and bulk water.
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Affiliation(s)
- Henry S Ashbaugh
- Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, Louisiana 70118, USA
| | - J Wesley Barnett
- Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, Louisiana 70118, USA
| | - Alexander Saltzman
- Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, Louisiana 70118, USA
| | - Mae E Langrehr
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware 19716, USA
| | - Hayden Houser
- Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, Louisiana 70118, USA
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24
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Resolving solvophobic interactions inferred from experimental solvation free energies and evaluated from molecular simulations. Chem Phys Lett 2017. [DOI: 10.1016/j.cplett.2016.11.038] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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25
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Cerdeiriña CA, Widom B. Osmotic Second Virial Coefficients of Aqueous Solutions from Two-Component Equations of State. J Phys Chem B 2016; 120:13144-13151. [DOI: 10.1021/acs.jpcb.6b09912] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Claudio A. Cerdeiriña
- Departamento
de Física Aplicada, Universidad de Vigo, Campus del Agua, Ourense 32004, Spain
- Department
of Chemistry, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, United States
| | - B. Widom
- Department
of Chemistry, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, United States
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26
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Pratt LR, Chaudhari MI, Rempe SB. Statistical Analyses of Hydrophobic Interactions: A Mini-Review. J Phys Chem B 2016; 120:6455-60. [PMID: 27258151 DOI: 10.1021/acs.jpcb.6b04082] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This review focuses on the striking recent progress in solving for hydrophobic interactions between small inert molecules. We discuss several new understandings. First, the inverse temperature phenomenology of hydrophobic interactions, i.e., strengthening of hydrophobic bonds with increasing temperature, is decisively exhibited by hydrophobic interactions between atomic-scale hard sphere solutes in water. Second, inclusion of attractive interactions associated with atomic-size hydrophobic reference cases leads to substantial, nontrivial corrections to reference results for purely repulsive solutes. Hydrophobic bonds are weakened by adding solute dispersion forces to treatment of reference cases. The classic statistical mechanical theory for those corrections is not accurate in this application, but molecular quasi-chemical theory shows promise. Finally, because of the masking roles of excluded volume and attractive interactions, comparisons that do not discriminate the different possibilities face an interpretive danger.
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Affiliation(s)
- Lawrence R Pratt
- Department of Chemical and Biomolecular Engineering, Tulane University , New Orleans, Louisiana 70118, United States
| | - Mangesh I Chaudhari
- Center for Biological and Engineering Sciences, Sandia National Laboratories , Albuquerque, New Mexico 87185, United States
| | - Susan B Rempe
- Center for Biological and Engineering Sciences, Sandia National Laboratories , Albuquerque, New Mexico 87185, United States
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27
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Affiliation(s)
- Dor Ben-Amotz
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907;
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28
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Urrutia I, Paganini IE. Virial series for inhomogeneous fluids applied to the Lennard-Jones wall-fluid surface tension at planar and curved walls. J Chem Phys 2016; 144:174102. [DOI: 10.1063/1.4947587] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Ignacio Urrutia
- Departamento de Física de la Materia Condensada, Centro Atómico Constituyentes, CNEA, Av.Gral. Paz 1499, 1650 Pcia. de Buenos Aires, Argentina and CONICET, Avenida Rivadavia 1917, C1033AAJ Buenos Aires, Argentina
| | - Iván E. Paganini
- Departamento de Física de la Materia Condensada, Centro Atómico Constituyentes, CNEA, Av.Gral. Paz 1499, 1650 Pcia. de Buenos Aires, Argentina and CONICET, Avenida Rivadavia 1917, C1033AAJ Buenos Aires, Argentina
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29
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Chaudhari MI, Rempe SB, Asthagiri D, Tan L, Pratt LR. Molecular Theory and the Effects of Solute Attractive Forces on Hydrophobic Interactions. J Phys Chem B 2016; 120:1864-70. [DOI: 10.1021/acs.jpcb.5b09552] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Mangesh I. Chaudhari
- Center
for Biological and Material Sciences, Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
| | - Susan B. Rempe
- Center
for Biological and Material Sciences, Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
| | - D. Asthagiri
- Department
of Chemical and Biomolecular Engineering, Rice University, Houston, Texas 77005, United States
| | - L. Tan
- Department
of Chemical and Biomolecular Engineering, Tulane University, New Orleans, Louisiana 70118, United States
| | - L. R. Pratt
- Department
of Chemical and Biomolecular Engineering, Tulane University, New Orleans, Louisiana 70118, United States
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30
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Mochizuki K, Koga K. Cononsolvency behavior of hydrophobes in water + methanol mixtures. Phys Chem Chem Phys 2016; 18:16188-95. [DOI: 10.1039/c6cp01496h] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The molecular origin of cononsolvency behavior is explored using molecular dynamics simulations.
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Affiliation(s)
- Kenji Mochizuki
- Department of Chemistry
- Faculty of Science
- Okayama University
- Okayama 700-8530
- Japan
| | - Kenichiro Koga
- Department of Chemistry
- Faculty of Science
- Okayama University
- Okayama 700-8530
- Japan
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31
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Mochizuki K, Sumi T, Koga K. Driving forces for the pressure-induced aggregation of poly(N-isopropylacrylamide) in water. Phys Chem Chem Phys 2016; 18:4697-703. [DOI: 10.1039/c5cp07674a] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Driving forces for the pressure-induced aggregation of poly(N-isopropylacrylamide) in water are discussed.
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Affiliation(s)
- Kenji Mochizuki
- Department of Chemistry
- Faculty of Science
- Okayama University
- Okayama 700-8530
- Japan
| | - Tomonari Sumi
- Department of Chemistry
- Faculty of Science
- Okayama University
- Okayama 700-8530
- Japan
| | - Kenichiro Koga
- Department of Chemistry
- Faculty of Science
- Okayama University
- Okayama 700-8530
- Japan
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