In-plane distribution in mixtures of cationic and anionic surfactants

Carriere, David; Belloni, Luc; Demé, Bruno; Dubois, M.; Vautrin, Claire; Meister, Annette; Zemb, Thomas

doi:10.1039/b912286a

Cited by 36 publications

(42 citation statements)

References 43 publications

(53 reference statements)

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“…Other works on catanionic surfactant mixtures also imply partitioning of lipids at a molecular level, as proposed in refs 60−62 and shown by means of contrast matching small angle neutron scattering. 61 Additional Insights into the Mechanisms of Formation. Superimposing the pH-dependent SAXS data presented in Figure 3 shows an interesting, very unique feature: practically all systems have at least one value of the wavevector q which is constant throughout the variation in pH.…”

Section: Langmuirmentioning

confidence: 99%

Self-Assembly Mechanism of pH-Responsive Glycolipids: Micelles, Fibers, Vesicles, and Bilayers

et al. 2016

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A set of four structurally related glycolipids are described: two of them have one glucose unit connected to either stearic or oleic acid, and two other ones have a diglucose headgroup (sophorose) similarly connected to either stearic or oleic acid. The self-assembly properties of these compounds, poorly known, are important to know due to their use in various fields of application from cleaning to cosmetics to medical. At basic pH, they all form mainly small micellar aggregates. At acidic pH, the oleic and stearic derivatives of the monoglucose form, respectively, vesicles and bilayer, while the same derivatives of the sophorose headgroup form micelles and twisted ribbons. We use pH-resolved in situ small angle X-ray scattering (SAXS) under synchrotron radiation to characterize the pH-dependent mechanism of evolution from micelles to the more complex aggregates at acidic pH. By pointing out the importance of the COO − /COOH ratio, the melting temperature, T m , of the lipid moieties, hydration of the glycosidic headgroup, the packing parameter, membrane rigidity, and edge stabilization, we are now able to draw a precise picture of the full self-assembly mechanism. This work is a didactical illustration of the complexity of the self-assembly process of a stimuli-responsive amphiphile during which many concomitant parameters play a key role at different stages of the process.

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Section: Langmuirmentioning

confidence: 99%

Self-Assembly Mechanism of pH-Responsive Glycolipids: Micelles, Fibers, Vesicles, and Bilayers

et al. 2016

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“…the osmotic repulsion between discs is known; 4 3. the local crystalline in plane order is known; 5 4. the ternary phase prism important for the determination of the temperature range for preparing and storing the emulsions is known. 6,7 For these reasons, catanionics seem to be a powerful emulsifier.…”

Section: Introductionmentioning

confidence: 99%

Pickering emulsions stabilized by stacked catanionic micro-crystals controlled by charge regulation

et al. 2011

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In this paper the mechanism behind the stabilization of Pickering emulsions by stacked catanionic micro-crystals is described. A temperature-quench of mixtures of oppositely charged surfactants (catanionics) and tetradecane from above the chain melting temperature to room temperature produces stable oil-in-water (o/w) Pickering emulsions in the absence of Ostwald ripening. The oil droplets are decorated by stacks of crystalline discs. The stacking of these discs is controlled by charge regulation as derived from conductivity, scattering and zeta potential measurements. Catanionic nanodiscs are ideal solid particles to stabilize Pickering emulsions since they present no density difference and a structural surface charge which is controlled by the molar ratio between anionic and cationic components. The contact angle of catanionic nanodiscs at a water/oil interface is also controlled by the nonstoichiometry of the components. The resulting energy of adhesion and the repulsion between droplets is much larger than kT. As a consequence of these unique properties of nanodiscs, this type of emulsions presents an extremely high resistance towards coalescence and creaming, even in the presence of salt.

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“…Previous work has shown only hexagonal packing of molecules within catanionic membranes where the ionization state of the cationic component does not depend on pH (25,39). In contrast, the ionization state of each of the molecules studied here is pH dependent, which enables us to control the membrane crystal structure by varying the degree of ionization among the headgroups.…”

Section: Discussionmentioning

confidence: 77%

“…The phase behavior of cationic and anionic amphiphiles is determined by many parameters, such as the amphiphile mixing ratio, concentration, and molecular structure (25)(26)(27). We recently studied mixtures +3 cations and -1 anions forming catanionic membranes (14).…”

Section: Significancementioning

confidence: 99%

Crystalline polymorphism induced by charge regulation in ionic membranes

Leung

Palmer

Kewalramani

et al. 2013

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

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The crystallization of molecules with polar and hydrophobic groups, such as ionic amphiphiles and proteins, is of paramount importance in biology and biotechnology. By coassembling dilysine (+2) and carboxylate (-1) amphiphiles of various tail lengths into bilayer membranes at different pH values, we show that the 2D crystallization process in amphiphile membranes can be controlled by modifying the competition of long-range and shortrange interactions among the polar and the hydrophobic groups. The pH and the hydrophobic tail length modify the intermolecular packing and the symmetry of their crystalline phase. For hydrophobic tail lengths of 14 carbons (C 14 ), we observe the coassembly into crystalline bilayers with hexagonal molecular ordering via in situ small-and wide-angle X-ray scattering. As the tail length increases, the hexagonal lattice spacing decreases due to an increase in van der Waals interactions, as demonstrated by atomistic molecular dynamics simulations. For C 16 and C 18 we observe a reentrant crystalline phase transition sequence, hexagonalrectangular-C-rectangular-P-rectangular-C-hexagonal, as the solution pH is increased from 3 to 10.5. The stability of the rectangular phases, which maximize tail packing, increases with increasing tail length. As a result, for very long tails (C 22 ), the possibility of observing packing symmetries other than rectangular-C phases diminishes. Our work demonstrates that it is possible to systematically exchange chemical and mechanical energy by changing the solution pH value within a range of physiological conditions at room temperature in bilayers of molecules with ionizable groups.amphiphilic membranes | self-assembly | hydrophobic interaction N ature uses electrostatic interactions among positively and negatively charged groups to induce the organization of biomolecules into highly complex structures that respond to ionic changes (1, 2). The structure of the aggregates at specific ionic conditions is intimately related to its function. Therefore, understanding the mechanisms that control the structure of molecules with hydrophobic and polar groups at physiological conditions is of great importance in molecular biology and biotechnology. In particular, amphiphilic molecules that have polar ionizable groups, such as proteins and lipids, can change their structures and functions in response to the pH and the concentration of ions in the solution (3), thereby affecting their physical properties and functions. For example, the structure of lipid membranes affects the structure and activity of membrane-bound proteins (4-6). Furthermore, the intermolecular packing density and structure are known to affect the molecular diffusion rates of water and ions across membranes (7,8). Changing the packing density of molecules within membranes could also be useful for controlling encapsulation and release efficiency of molecules inside a vesicle (9). Additionally the spacing between amphiphilic molecules within a membrane may control the capacity to encapsulate or release...

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In-plane distribution in mixtures of cationic and anionic surfactants

Cited by 36 publications

References 43 publications

Self-Assembly Mechanism of pH-Responsive Glycolipids: Micelles, Fibers, Vesicles, and Bilayers

Self-Assembly Mechanism of pH-Responsive Glycolipids: Micelles, Fibers, Vesicles, and Bilayers

Pickering emulsions stabilized by stacked catanionic micro-crystals controlled by charge regulation

Crystalline polymorphism induced by charge regulation in ionic membranes

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