A small molecular size system giving unexpected surface effects: α-Cyclodextrin + sodium dodecyl sulfate in water

Hernández-Pascacio, Jorge; Banquy, Xavier; Pérez-Casas, Silvia; Costas, Miguel; Amigo, Alfredo; Piñeiro, Ángel

doi:10.1016/j.jcis.2008.09.002

Cited by 15 publications

(18 citation statements)

References 29 publications

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“…However, based on ab-initio calculations to interpret their spectroscopic measurements, Mascetti et al concluded a perpendicular stacking of the CDs. We clearly observe tilted layers (Video S1), which corroborates with experimental data for the adsorption of CD at the water-air interface with highly concentrated CD solutions [25]–[30].…”

Section: Resultssupporting

confidence: 88%

Molecular Mechanism of Cyclodextrin Mediated Cholesterol Extraction

2011

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The depletion of cholesterol from membranes, mediated by β-cyclodextrin (β-CD) is well known and documented, but the molecular details of this process are largely unknown. Using molecular dynamics simulations, we have been able to study the CD mediated extraction of cholesterol from model membranes, in particular from a pure cholesterol monolayer, at atomic resolution. Our results show that efficient cholesterol extraction depends on the structural distribution of the CDs on the surface of the monolayer. With a suitably oriented dimer, cholesterol is extracted spontaneously on a nanosecond time scale. Additional free energy calculations reveal that the CDs have a strong affinity to bind to the membrane surface, and, by doing so, destabilize the local packing of cholesterol molecules making their extraction favorable. Our results have implications for the interpretation of experimental measurements, and may help in the rational design of efficient CD based nano-carriers.

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Section: Resultssupporting

confidence: 88%

Molecular Mechanism of Cyclodextrin Mediated Cholesterol Extraction

2011

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“…The system selected for this study, a α-CD 2 SDS 1 complex, proved to be extremely sensitive to different factors including temperature, concentration range, and the presence of water/air interface. A number of different experimental methods including calorimetry, surface tension, rheology, neutron reflectometry, ellipsometry, and several microscopies were employed to characterize its behavior under different conditions [1,5,6,23]. Several studies were also performed by using β-CD 2 SDS 1 instead of α-CD 2 SDS 1 complexes [4,27,28], as well as other similar structures that provide interesting self-assembly patterns in the bulk solution and at interfaces [29,30].…”

Section: Discussionmentioning

confidence: 99%

“…Approximately 500-ns-long MD trajectories for the simulations based on the GROMOS force field and 150-ns-long trajectories for the simulations using AMBER, all of them at 283 K, were generated. This temperature was employed because both the adsorption and the formation of 2:1 complexes are much more favorable at 283 K than at 298 K [5,6,23]. The NPT ensemble was employed for the simulations in solution and in the NVT ensemble for the simulation in the presence of water/air interfaces.…”

Section: Set Up Of the Simulation Boxes And MD Simulation Parametersmentioning

confidence: 99%

“…The behavior of native cyclodextrins (CDs) in aqueous solution and at the air/water interface is much more complex than expected just considering their apparently simple molecular structure [1][2][3]. Consequently, the correct prediction of their properties and skills such as their solubility, their ability to adsorb at interfaces, or to encapsulate a variety of molecules is not straightforward; not to mention their propensity to aggregate forming different patterns in the bulk solution and at the water/air interface [4][5][6]. It is not a surprise then that the behavior of native and modified CDs, as well as that of the supramolecular complexes they form upon interacting with different types of molecules, is not trivial [7].…”

Section: Introductionmentioning

confidence: 99%

“…In the present paper, we will focus on the behavior of the supramolecular 2:1 complex formed by α-CD and sodium dodecyl sulfate (SDS) (see Figure 1) in the bulk of aqueous solutions and also at water/air interfaces. CD-surfactant mixtures are especially interesting because they proved to exhibit interesting aggregation, mechanical, and adsorption properties under certain experimental conditions (concentration range and temperature) where the presence of 2:1 complexes dominate the solution [4][5][6][27][28][29][30] but the molecular interactions leading to such behavior are unclear. This can be illustrated by an specific example: The adsorption of α-CD 2 SDS 1 complexes at interfaces leading to a monolayer has been conclusively demonstrated by different methods including surface tension, rheology, ellipsometry, Brewster angle microscopy (BAM), atomic force microscopy (AFM), and neutron reflectometry (NR), [5,6,23] although the adsorption driving force of those structures at the interface are still unknown.…”

Section: Introductionmentioning

confidence: 99%

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Rings, Hexagons, Petals, and Dipolar Moment Sink-Sources: The Fanciful Behavior of Water around Cyclodextrin Complexes

et al. 2020

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The basket-like geometry of cyclodextrins (CDs), with a cavity able to host hydrophobic groups, makes these molecules well suited for a large number of fundamental and industrial applications. Most of the established CD-based applications rely on trial and error studies, often ignoring key information at the atomic level that could be employed to design new products and to optimize their use. Computational simulations are well suited to fill this gap, especially in the case of CD systems due to their low number of degrees of freedom compared with typical macromolecular systems. Thus, the design and validation of solid and efficient methods to simulate and analyze CD-based systems is key to contribute to this field. The behavior of supramolecular complexes critically depends on the media where they are embedded, so the detailed characterization of the solvent is required to fully understand these systems. In the present work, we use the inclusion complex formed by two α-CDs and one sodium dodecyl sulfate molecule to test eight different parameterizations of the GROMOS and AMBER force fields, including several methods aimed to increase the conformational sampling in computational molecular dynamics simulation trajectories. The system proved to be extremely sensitive to the employed force field, as well as to the presence of a water/air interface. In agreement with previous experiments and in contrast to the results obtained with AMBER, the analysis of the simulations using GROMOS showed a quick adsorption of the complex to the interface as well as an extremely exotic behavior of the water molecules surrounding the structure both in the bulk aqueous solution and at the water surface. The chirality of the CD molecule seems to play an important role in this behavior. All together, these results are expected to be useful to better understand the behavior of CD-based supramolecular complexes such as adsorption or aggregation driving forces, as well as to introduce new methods able to speed up general MD simulations.

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