Pyrene binding to persistent micelles formed from a dendro-calixarene

Yihwa, Chang; Kellermann, Michael; Becherer, Miriam; Hirsch, Andreas; Bohne, Cornelia

doi:10.1039/b617800f

Cited by 24 publications

(30 citation statements)

References 21 publications

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“…3,4 At increasing concentration of bile salts, primary aggregates further aggregate to yield loosely held structures, called secondary aggregates and they are stabilized by the hydrogen bonding interaction between the OH group of bile salts and water molecules in the medium (Scheme S1, ESI †). [21][22][23] The binding dynamics of the aggregates is strongly influenced by the ionic strength of the medium and it is well known that the Critical Micellar Concentration (CMC) of the aggregates is decreased along with the increase in the size of the aggregates, as we increase the ionic strength of the medium and the size increase is more prominent in dihydroxy bile salts compared to other trihydroxy salts due to their substantial hydrophobicity. 15,16 However, estimation of the relative amount of bile salts which can be found in different aggregation stages is still a challenging problem and recently, Miranda et al, using fluorescent dansyl derivatives of bile salts, have demonstrated medium dependent aggregation behavior.…”

Section: Introductionmentioning

confidence: 99%

Modulation of the aggregation properties of sodium deoxycholate in presence of hydrophilic imidazolium based ionic liquid: water dynamics study to probe the structural alteration of the aggregates

Kundu

Banik

Roy

et al. 2015

Phys. Chem. Chem. Phys.

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In this article, we have investigated the effect of a hydrophilic ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim]-BF4), on the aggregation properties of a biological surfactant, sodium deoxycholate (NaDC), in water. In solution, unlike conventional surfactants it shows stepwise aggregation and the effect of the conventional ionic liquid on the aggregation properties is rather interesting. We have observed concentration dependent dual role of the ionic liquid; at their low concentration, the aggregated structure of NaDC reorganizes itself into an elongated rod like structure. However, the aggregated network is disintegrated into small aggregates upon further addition of ionic liquid. TEM (Transmission Electron Microscopy), SEM (Scanning Electron Microscopy) and FLIM (Fluorescence Lifetime Imaging Microscopy) images also confirmed the structural alteration of NaDC upon varying the concentration of the ionic liquid. The proton NMR data indicate that hydrophobic as well as electrostatic interaction is solely responsible for such structural adaptation of NaDC in the presence of an ionic liquid. The host-guest interaction inside the aggregates is monitored using Coumarin-153 (C-153) and the location of C-153 is probed by varying the excitation wavelength from 375 nm to 440 nm and the two binding sites of the aggregates are affected in a different fashion in the presence of ionic liquid. Excitation in the blue region selects the fluorophores which preferably bind to the buried region of the aggregates, whereas 440 nm excitation corresponds to the guest molecules which are exposed to the solvent molecules. The average solvation time of C-153 is increased in the presence of 1.68 wt% [bmim]-BF4 at λexc = 440 nm i.e. the probe molecules relocate themselves to a more restricted region. However, the average solvation time became 2.6 times faster in the presence of 11.2 wt% [bmim]-BF4, which corresponds to a more polar and exposed region. The time resolved anisotropy measurements and polarity determined by pyrene also supported our results in addition to solvation dynamics measurements. In summary, ionic liquids can modulate the host-guest interaction of bile salt aggregates, which can be used as nanocarriers for drug delivery.

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Section: Introductionmentioning

confidence: 99%

Modulation of the aggregation properties of sodium deoxycholate in presence of hydrophilic imidazolium based ionic liquid: water dynamics study to probe the structural alteration of the aggregates

Kundu

Banik

Roy

et al. 2015

Phys. Chem. Chem. Phys.

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“…They are formed as aggregates of tailored T-shaped amphiphiles. [1] Such micelles consist of dendrimeric hydrophilic head groups and hydrophobic core groups bound to a central scaffold, which may be a calixarene [1][2][3] or a substituted fullerene. [3][4][5][6] The interaction of ions with surfaces of biological and synthetic nanostructures and their influence on hydrophobic interactions have become the subject of intense current interest.…”

Section: Introductionmentioning

confidence: 99%

Counterions Control the Self‐Assembly of Structurally Persistent Micelles: Theoretical Prediction and Experimental Observation of Stabilization by Sodium Ions

Jäger

Hirsch

Schade

et al. 2009

Chemistry A European J

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We show by molecular-dynamics (MD) simulations and cryo-transmission electron microscopy (cryo-TEM) experiments that the size and form of structurally persistent micelles formed by the T-shaped amphiphile 1 are controlled by the counterions. The two techniques reveal that the micelles are specifically stabilized by sodium counterions relative to potassium ions. Both the simulations and the cryo-TEM experiments suggest that the micelles are stabilized by strongly conserved hydrated contact ion pairs with sodium counterions but not with potassium ions. We suggest that the TEM is observing local high density due to hydrated carboxylate/sodium ion pairs at the surface of the micelle. A high concentration of such structures is found in MD simulations with sodium counterions, but not with potassium.

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“…1 in non-polar solution. A shift at a particular concentration of surfactant has been used to determine the cmc of conventional surfactants (25). The oligoester compounds studied previously are not typical surfactants but do show a change over a fairly broad concentration in the range of 10-50 mM; HO 2 C-Oct-DecOct-G(10)-OH is typical at 33 mM (22).…”

Section: Aggregation In Aqueous Solutionmentioning

confidence: 99%

Membrane activity of 3-hydroxyglutarate diesters

Genge

Moszynski

Thompson

et al. 2011

Supramolecular Chemistry

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The synthesis and characterisation of the transport activity and membrane localisation of three 3-hydroxyglutarate diesters containing saturated and diphenylacetylene-derived groups are described. In bilayer vesicles and planar bilayers, the two compounds bearing a terminal carboxylic acid form active ion channels; a related neutral compound is inactive. Nonlinear current-voltage behaviour is observed for the active diphenylacetylene-derived diester. The transport activity occurs at concentrations that are substantially below the level at which the compounds aggregate. Diphenylacetylene-derived fluorescence allows the partitioning and the aggregation states of the compounds to be probed. It is clear that the active compounds do not simply act as detergents, but form defined, if irregular, ion channels in the membrane.

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Pyrene binding to persistent micelles formed from a dendro-calixarene

Cited by 24 publications

References 21 publications

Modulation of the aggregation properties of sodium deoxycholate in presence of hydrophilic imidazolium based ionic liquid: water dynamics study to probe the structural alteration of the aggregates

Modulation of the aggregation properties of sodium deoxycholate in presence of hydrophilic imidazolium based ionic liquid: water dynamics study to probe the structural alteration of the aggregates

Counterions Control the Self‐Assembly of Structurally Persistent Micelles: Theoretical Prediction and Experimental Observation of Stabilization by Sodium Ions

Membrane activity of 3-hydroxyglutarate diesters

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