Universal Repulsive Contribution to the Solvent-Induced Interaction Between Sizable, Curved Hydrophobes

Jabes, B. Shadrack; Bratko, D.; Luzar, Alenka

doi:10.1021/acs.jpclett.6b01442

Cited by 8 publications

(22 citation statements)

References 39 publications

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“…For convex surfaces, results in Fig. 1B are also in good agreement with those of Jabes et al (52), who found that hydration shell compressibility reduces by about 22% near a hydrocarbon-coated cylinder with κ = 1.13 nm −1 , relative to that near a flat plate. Our results highlight an asymmetric dependence of hydration shell compressibility on the sign of nanotube curvature.…”

Section: Resultssupporting

confidence: 89%

Hydrophobicity of proteins and nanostructured solutes is governed by topographical and chemical context

Venkateshwaran

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

100

126

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Hydrophobic interactions drive many important biomolecular selfassembly phenomena. However, characterizing hydrophobicity at the nanoscale has remained a challenge due to its nontrivial dependence on the chemistry and topography of biomolecular surfaces. Here we use molecular simulations coupled with enhanced sampling methods to systematically displace water molecules from the hydration shells of nanostructured solutes and calculate the free energetics of interfacial water density fluctuations, which quantify the extent of solute-water adhesion, and therefore solute hydrophobicity. In particular, we characterize the hydrophobicity of curved graphene sheets, self-assembled monolayers (SAMs) with chemical patterns, and mutants of the protein hydrophobin-II. We find that water density fluctuations are enhanced near concave nonpolar surfaces compared with those near flat or convex ones, suggesting that concave surfaces are more hydrophobic. We also find that patterned SAMs and protein mutants, having the same number of nonpolar and polar sites but different geometrical arrangements, can display significantly different strengths of adhesion with water. Specifically, hydroxyl groups reduce the hydrophobicity of methyl-terminated SAMs most effectively not when they are clustered together but when they are separated by one methyl group. Hydrophobin-II mutants show that a charged amino acid reduces the hydrophobicity of a large nonpolar patch when placed at its center, rather than at its edge. Our results highlight the power of water density fluctuations-based measures to characterize the hydrophobicity of nanoscale surfaces and caution against the use of additive approximations, such as the commonly used surface area models or hydropathy scales for characterizing biomolecular hydrophobicity and the associated driving forces of assembly.nanotube | curvature | chemical pattern | hydrophilicity | graphene H ydrophobic interactions drive many important biological and colloidal self-assembly processes (1-6). During such assembly, the hydration shells of the associating solutes are disrupted, replacing hydrophobic-water contacts with hydrophobic-hydrophobic ones. Characterizing how strongly water adheres to a given solute is, therefore, directly relevant to the strength of hydrophobic interactions between solutes. Macroscopically, surface-water adhesion is quantified by measuring the water droplet contact angle on a surface. However, such characterization does not translate usefully to proteins and other nanoscale solutes. Indeed, characterizing how strongly or weakly a protein surface or a specific patch on it adheres to water (i.e., its hydrophobicity) is incredibly challenging and has necessitated the use of simplifying assumptions.To this end, simple surface area (SA) models have been used to estimate the driving force for assembly, ∆G = γ∆A, where ∆A is the nonpolar SA buried upon assembly and γ is an appropriate surface tension (7-9). However, the value of γ used in popular models is nearly an order of magnitude lower t...

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Section: Resultssupporting

confidence: 89%

Hydrophobicity of proteins and nanostructured solutes is governed by topographical and chemical context

Venkateshwaran

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

100

126

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“…This success of macroscopic theory may seem surprising, given that the blocks we consider have the microscopic cross sectional area ≈10σ × 5σ. However, it is in keeping with recent simulation studies 6,8 of water induced interactions between hydrophobes. In contrast, when both blocks are solvophilic, the potential W (x G ) is oscillatory but overall repulsive and exhibits only a weak dependence on β∆µ; see Fig.…”

Section: Discussionsupporting

confidence: 85%

“…This can also be seen from the inset which shows the adsorption (10). Although Γ is somewhat larger in magnitude than that for the wall potential (8), displayed in the inset to Fig. 4, it remains finite at coexistence.…”

Section: B Single Soft Lennard-jones Wallmentioning

confidence: 60%

Solvent fluctuations around solvophobic, solvophilic, and patchy nanostructures and the accompanying solvent mediated interactions

Chacko

Evans

Archer

2017

The Journal of Chemical Physics

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Using classical density functional theory(DFT), we calculate the density profile ρ(𝐫) and local compressibility χ(𝐫) of a simple liquidsolvent in which a pair of blocks with (microscopic) rectangular cross section are immersed. We consider blocks that are solvophobic, solvophilic and also ones that have both solvophobic and solvophilic patches. Large values of χ(𝐫) correspond to regions in space where the liquid density is fluctuating most strongly. We seek to elucidate how enhanced density fluctuations correlate with the solvent mediated force between the blocks, as the distance between the blocks and the chemical potential of the liquid reservoir vary. For sufficiently solvophobic blocks, at small block separations and small deviations from bulk gas-liquid coexistence, we observe a strongly attractive (near constant) force, stemming from capillary evaporation to form a low density gas-like intrusion between the blocks. The accompanying χ(𝐫) exhibits a structure which reflects the incipient gas-liquid interfaces that develop. We argue that our model system provides a means to understanding the basic physics of solvent mediated interactions between nanostructures, and between objects such as proteins in water that possess hydrophobic and hydrophilic patches.

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“…In practice, we varied wall while keeping the liquid properties constant and measured the corresponding contact angle, θ. We note that additional complexities that also influence the surface solvophobicity including functionalization and polarity effects can not be captured with our present model 38 .…”

Section: A Studied Systemmentioning

confidence: 82%

“…Along with the wetting properties of the solid, the role of its geometrical structure was also covered in several studies [37][38][39] . For example, Jabes et al recently demonstrated that using the same solid composition and size, qualitatively different solvent-mediated forces can be obtained only by changing the solid shape between fullerenes, nanotubes and graphene-like structures 38 . Altogether, this work is integrated to a general mean-field theory of hydrophobicity developed by Lum, Chandler and Weeks 40 and further refined in more recent publications 31,41,42 .…”

Section: Introductionmentioning

confidence: 99%

Solvent-mediated interactions between nanostructures: From water to Lennard-Jones liquid

Lam

Lutsko

2018

The Journal of Chemical Physics

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Solvent-mediated interactions emerge from complex mechanisms that depend on the solute structure, its wetting properties and the nature of the liquid. While numerous studies have focused on the two first influences, here, we compare results from water and Lennard-Jones liquid in order to reveal to what extent solvent-mediated interactions are universal with respect to the nature of the liquid. Besides the influence of the liquid, results were obtained with classical density functional theory and brute-force molecular dynamics simulations which allows us to contrast these two numerical techniques. arXiv:1809.06069v1 [cond-mat.soft]

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Universal Repulsive Contribution to the Solvent-Induced Interaction Between Sizable, Curved Hydrophobes

Cited by 8 publications

References 39 publications

Hydrophobicity of proteins and nanostructured solutes is governed by topographical and chemical context

Hydrophobicity of proteins and nanostructured solutes is governed by topographical and chemical context

Solvent fluctuations around solvophobic, solvophilic, and patchy nanostructures and the accompanying solvent mediated interactions

Solvent-mediated interactions between nanostructures: From water to Lennard-Jones liquid

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