Association behaviour of glucitol amine gemini surfactants

Eijk, Marcel C. P. van; Bergsma, Mark; Marrink, Siewert J.

doi:10.1140/epje/i2002-10012-6

Cited by 7 publications

(2 citation statements)

References 27 publications

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“…Furthermore, the absolute magnitude, R g / R h ≈ 2, is consistent with the formation of large wormlike or cylindrical micelles. , Indeed, the formation of cylindrical micelles also explains the increased viscosity in the relevant pH regions because this often is accompanied by viscosity changes in the solution. Interestingly, a pH-induced vesicle-to-cylindrical-micelle transition has been theoretically predicted for structurally related gemini surfactants using molecular dynamics and self-consistent-field calculations . It may also be noted that the R g / R h ratio is close to 1 for the vesicular dispersion of GS3 at pH 6.64, which is in accordance with the results obtained for spherical vesicles of low polydispersity .…”

Section: Resultssupporting

confidence: 85%

Sugar-Based Gemini Surfactants with pH-Dependent Aggregation Behavior: Vesicle-to-Micelle Transition, Critical Micelle Concentration, and Vesicle Surface Charge Reversal

et al. 2003

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In a recent report, we presented data on the rich and unusual pH-dependent aggregation behavior of a sugar-based (reduced glucose) gemini surfactant (Johnsson et al. J. Am. Chem. Soc. 2003, 125, 757). In the present study, we extend the previous investigation by introducing a different sugar headgroup (reduced mannose), by varying the spacer between the two main surfactant parts, and by introducing, in one of the surfactants, an amide linkage (instead of an amine linkage) between the headgroup and the unsaturated (C18:1) hydrocarbon tails. The aggregation behavior of these four gemini surfactants has been studied and compared by means of light scattering, cryo-transmission electron microscopy, electrophoretic mobility, and fluorescence measurements. We find that all four surfactants form vesicles near neutral or high pH. However, the vesicles made from the amine-containing geminis are transformed into cylindrical or wormlike micelles at lower pH values (pH < ∼5.5). The micellization is driven mainly by an increased electrostatic repulsion, caused by the protonation of the tertiary amino groups, and we find that the nature of the sugar or spacer has little influence on this process. At low pH (pH 2), solely small globular micelles are found, and the critical micelle concentration at this pH is about 0.005-0.010 mM for the different amine-containing surfactants. As was expected, the gemini surfactant with the amide instead of the amine functional groups in the headgroup does not undergo the vesicle-to-micelle transition but displays only vesicle formation within the investigated pH range. The electrophoretic mobility measurements on the vesicular samples formed from the amine-containing geminis show that the vesicles are cationic below pH ∼7-7.5; however, the vesicles acquire a substantial negative charge at a higher pH. The most probable explanation for this charge reversal is a strong adsorption (or binding) of hydroxide ions onto the vesicle surface. In accordance with this hypothesis, we find that the vesicles made from the amide-containing gemini are anionic (no protonation) even at a low pH (pH <5). Using a simple Poisson-Boltzmann model, we are able to describe the obtained ζ-potential profiles reasonably well and derive a hydroxide-ion binding constant (KOH) for the respective systems. We find that the nature of the sugar does have a small influence on KOH. The colloidal stability of all four types of the gemini vesicles seems to be well-described by the classical Derjaguin-Landau-Verwey-Overbeek theory, and the vesicles aggregate/flocculate rapidly in the limit of low surface potential. However, the flocculated vesicles can be easily redispersed by, for example, raising the pH of the solution, and this flocculation/redispersal process is completely reversible.

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Section: Resultssupporting

confidence: 85%

Sugar-Based Gemini Surfactants with pH-Dependent Aggregation Behavior: Vesicle-to-Micelle Transition, Critical Micelle Concentration, and Vesicle Surface Charge Reversal

et al. 2003

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“…The spacing of the bilayers in the free vesicles is obtained with intercalation of the alkyl tails up to the double bonds (Figure , top left). Bilayer formation with intercalation is also observed in a recent Molecular Dynamics study of the analogue with hexadecyl tails instead of the 9-octadecenyl and octadecyl chains in, respectively, 1 and 2 , and is in line with SAXS results for that compound . The lamellar phase for the lipoplex of 1 is illustrated (Figure , middle) for DNA possessing a 20 Å diameter and the alkyl chains intercalating to the double bond to reproduce the measured 59.8 Å spacing.…”

Section: Resultssupporting

confidence: 83%

Transfection Mediated by Gemini Surfactants: Engineered Escape from the Endosomal Compartment

et al. 2003

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The structure of the lipoplex formed from DNA and the sugar-based cationic gemini surfactant 1, which exhibits excellent transfection efficiency, has been investigated in the pH range 8.8-3.0 utilizing small-angle X-ray scattering (SAXS) and cryo-electron microscopy (cryo-TEM). Uniquely, three well-defined morphologies of the lipoplex were observed upon gradual acidification: a lamellar phase, a condensed lamellar phase, and an inverted hexagonal (H(II)) columnar phase. Using molecular modeling, we link the observed lipoplex morphologies and physical behavior to specific structural features in the individual surfactant, illuminating key factors in future surfactant design, viz., a spacer of six methylene groups, the presence of two nitrogens that can be protonated in the physiological pH range, two unsaturated alkyl tails, and hydrophilic sugar headgroups. Assuming that the mechanism of transfection by synthetic cationic surfactants involves endocytosis, we contend that the efficacy of gemini surfactant 1 as a gene delivery vehicle can be explained by the unprecedented observation of a pH-induced formation of the inverted hexagonal phase of the lipoplex in the endosomal pH range. This change in morphology leads to destabilization of the endosome through fusion of the lipoplex with the endosomal wall, resulting in release of DNA into the cytoplasm.

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Gemini‐Tenside: neue synthetische Vektoren zur Gentransfektion

et al. 2003

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Die oberflächenaktiven Eigenschaften kationischer Gemini‐Tenside werden zur Lösung des komplexen Problems der Gentransfektion in Zellen verwendet. Von nahezu 250 getesteten Substanzen, denen etwa 20 verschiedene Struktur‐Typen zugrunde liegen, zeigten viele eine gute In‐vitro‐Transfektionsaktivität. Das Tensid bindet und komprimiert DNS wirkungsvoll. Strukturelle und rechnerische Untersuchungen liefern ein brauchbares Modell des geformten Lipoplexes. Der Lipoplex kann durch die äußeren Membranen verschiedener Zelltypen dringen und so ins Cytoplasma gelangen. Die Freisetzung aus dem Endosom – ein Schlüsselschritt der Transfektion – könnte durch Veränderungen im Aggregationsverhalten des Lipoplexes bei fallendem pH‐Wert kontrolliert werden. Dies deutet auf ein Loslösen der DNS aus dem Lipoplex vor dem Eintritt in den Zellkern hin, wo das neue Gen mit hoher Effizienz exprimiert werden kann.

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Association behaviour of glucitol amine gemini surfactants

Cited by 7 publications

References 27 publications

Sugar-Based Gemini Surfactants with pH-Dependent Aggregation Behavior: Vesicle-to-Micelle Transition, Critical Micelle Concentration, and Vesicle Surface Charge Reversal

Sugar-Based Gemini Surfactants with pH-Dependent Aggregation Behavior: Vesicle-to-Micelle Transition, Critical Micelle Concentration, and Vesicle Surface Charge Reversal

Transfection Mediated by Gemini Surfactants: Engineered Escape from the Endosomal Compartment

Gemini‐Tenside: neue synthetische Vektoren zur Gentransfektion

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