Self-Assembly of Escin Molecules at the Air–Water Interface as Studied by Molecular Dynamics

Tsibranska, Sonya; Ivanova, Anela; Denkov, Nikolai D.

doi:10.1021/acs.langmuir.7b01719

Cited by 48 publications

(88 citation statements)

References 39 publications

(98 reference statements)

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“…Hence, either a fraction of the hydrophobic scaffold must be embedded in the aqueous subphase and/or the triterpenoid scaffold is strongly tilted with respect to the water-air interface. Both explanations are consistent with a recent simulation of β-aescin adsorption by molecular dynamics [42]. The inner layer, adjacent to the aqueous phase, was found to have a thickness of ≈1.4 nm.…”

Section: Structure Of the β-Aescin Monolayer At The Air-water Interfacesupporting

confidence: 91%

“…This will be discussed in more detail in Section 4. Also, the state of protonation was found to modify the inter-molecular interactions and thus the attractive and repulsive forces between β-aescin molecules [42,43].…”

Section: Micelle Formationmentioning

confidence: 99%

“…Tsibranska et al [42] performed classical atomistic dynamics simulations of neutral and ionized β-aescin molecules adsorbed at the vacuum-water interface (water with 10 mM NaCl) in order to clarify their orientation and interactions on the water surface. Thereby, the neutral form corresponds to β-aescin molecules at e.g., pH 4 and the ionized form to β-aescin at e.g., pH 8 when compared to experimental findings.…”

Section: Simulations Of a β-Aescin Monolayermentioning

confidence: 99%

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The Biosurfactant β-Aescin: A Review on the Physico-Chemical Properties and Its Interaction with Lipid Model Membranes and Langmuir Monolayers

2019

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This review discusses recent progress in physicochemical understanding of the action of the saponin β -aescin (also called β -escin), the biologically active component in the seeds of the horse chestnut tree Aesculus hippocastanum. β -Aescin is used in pharmacological and cosmetic applications showing strong surface activity. In this review, we outline the most important findings describing the behavior of β -aescin in solution (e.g., critical micelle concentration ( c m c ) and micelle shape) and special physicochemical properties of adsorbed β -aescin monolayers at the air–water and oil–water interface. Such monolayers were found to posses very special viscoelastic properties. The presentation of the experimental findings is complemented by discussing recent molecular dynamics simulations. These simulations do not only quantify the predominant interactions in adsorbed monolayers but also highlight the different behavior of neutral and ionized β -aescin molecules. The review concludes on the interaction of β -aescin with phospholipid model membranes in the form of bilayers and Langmuir monolayers. The interaction of β -aescin with lipid bilayers was found to strongly depend on its c m c . At concentrations below the c m c , membrane parameters are modified whereas above the c m c , complete solubilization of the bilayers occurs, depending on lipid phase state and concentration. In the presence of gel-phase phospholipids, discoidal bicelles form; these are tunable in size by composition. The phase behavior of β -aescin with lipid membranes can also be modified by addition of other molecules such as cholesterol or drug molecules. The lipid phase state also determines the penetration rate of β -aescin molecules into lipid monolayers. The strongest interaction was always found in the presence of gel-phase phospholipid molecules.

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Section: Structure Of the β-Aescin Monolayer At The Air-water Interfacesupporting

confidence: 91%

Section: Micelle Formationmentioning

confidence: 99%

Section: Simulations Of a β-Aescin Monolayermentioning

confidence: 99%

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The Biosurfactant β-Aescin: A Review on the Physico-Chemical Properties and Its Interaction with Lipid Model Membranes and Langmuir Monolayers

2019

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“…This might be due to a very specific arrangement of the aescin molecules inside the micelles. Molecular dynamics (MD) simulations by Tsibranska et al [52] for the self-assembly of aescin molecules at the water-air interface confirmed multiple attractive interactions between its hydrophobic and hydrophilic parts. Moreover, Penfold et al [43] proved this directed self-assembly experimentally by neutron reflectivity.…”

Section: Determination Of Cmc Aescinaf By Fluorescence Spectroscopymentioning

confidence: 98%

Self-Assembly of the Bio-Surfactant Aescin in Solution: A Small-Angle X-ray Scattering and Fluorescence Study

Dargel

Geisler

Hannappel

et al. 2019

Colloids and Interfaces

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This work investigates the temperature-dependent micelle formation as well as the micellar structure of the saponin aescin. The critical micelle concentration ( c m c ) of aescin is determined from the concentration-dependent autofluorescence (AF) of aescin. Values between c m c aescin , AF (10 ∘ C) = 0.38 ± 0.09 mM and c m c aescin , AF (50 ∘ C) = 0.32 ± 0.13 mM were obtained. The significance of this method is verified by tensiometry measurements. The value determined from this method is within the experimental error identical with values obtained from autofluorescence ( c m c aescin , T ( WP ) (23 ∘ C) = 0.33 ± 0.02 mM). The structure of the aescin micelles was investigated by small-angle X-ray scattering (SAXS) at 10 and 40 ∘ C. At low temperature, the aescin micelles are rod-like, whereas at high temperature the structure is ellipsoidal. The radii of gyration were determined to ≈31 Å (rods) and ≈21 Å (ellipsoid). The rod-like shape of the aescin micelles at low temperature was confirmed by transmission electron microscopy (TEM). All investigations were performed at a constant pH of 7.4, because the acidic aescin has the ability to lower the pH value in aqueous solution.

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“…On the other hand, the area per molecule for Escin molecules is similar for air-water and Hexadecane-water interfaces, while the dilatational and shear elasticities are much lower for Hexadecane-water interface, which is probably related to the effect of hexadecane molecules on the orientation of the escin molecules in the adsorption layer. In our previous studies [60,61] we performed classical atomistic dynamics simulations of adsorbed escin molecules on the water surface. The results revealed that long-range attraction between the hydrophobic aglycones, combined with intermediate dipole-dipole attraction and short-range hydrogen bonds between the sugar residues in escin molecules control the viscoelastic properties of escin adsorption layers on air-water interface.…”

Section: Interfacial Rheological Properties Of Saponinsmentioning

confidence: 99%

Role of interfacial elasticity for the rheological properties of saponin-stabilized emulsions

Tsibranska

Golemanov

Denkov

et al. 2020

Journal of Colloid and Interface Science

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HypothesisSaponins are natural surfactants which can provide highly viscoelastic interfaces. This property can be used to quantify precisely the effect of interfacial dilatational elasticity on the various rheological properties of bulk emulsions. ExperimentsWe measured the interfacial dilatational elasticity of adsorption layers from four saponins (Quillaja, Escin, Berry, Tea) adsorbed on hexadecane-water and sunflower oil-water interfaces. In parallel, the rheological properties under steady and oscillatory shear deformations were measured for bulk emulsions, stabilized by the same saponins (oil volume fraction between 75 and 85 %). FindingsQuillaja saponin and Berry saponin formed solid adsorption layers (shells) on the SFO-water interface. As a consequence, the respective emulsions contained non-spherical drops. For the other systems, the interfacial elasticities varied between 2 mN/m and 500 mN/m. We found that this interfacial elasticity has very significant impact on the emulsion shear elasticity, moderate effect on the dynamic yield stress, and no effect on the viscous stress of the respective steadily sheared emulsions. The last conclusion is not trivial, because the dilatational surface elasticity is known to have strong impact on the viscous stress of steadily sheared foams. Mechanistic explanations of all observed effects are described.3 1. Introduction.

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Self-Assembly of Escin Molecules at the Air–Water Interface as Studied by Molecular Dynamics

Cited by 48 publications

References 39 publications

The Biosurfactant β-Aescin: A Review on the Physico-Chemical Properties and Its Interaction with Lipid Model Membranes and Langmuir Monolayers

The Biosurfactant β-Aescin: A Review on the Physico-Chemical Properties and Its Interaction with Lipid Model Membranes and Langmuir Monolayers

Self-Assembly of the Bio-Surfactant Aescin in Solution: A Small-Angle X-ray Scattering and Fluorescence Study

Role of interfacial elasticity for the rheological properties of saponin-stabilized emulsions

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