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Blandamer, Michael J.; Briggs, Barbara; Cullis, Paul M.; Last, Philip M.; Engberts, Jan B. F. N.; Kacperska, Anna

doi:10.1023/a:1010159400429

Cited by 14 publications

(12 citation statements)

References 12 publications

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“…DODAB, on the other hand, has quite low CVC [2] and is poorly soluble in water below T m ≈ 43 • C. Above this critical temperature DODAB forms large unilamellar vesicles (LUV) at concentrations up to ca. 1 mM [1][2][3][4][5][6][7][8][9][10][11]13].…”

Section: Resultsmentioning

confidence: 99%

“…Anionic [11,12] and cationic [7,13] surfactants also modify the T m of DODAB and DODAC (dioctadecyldimethylammonium chloride). Sodium dodecyl sulphate (SDS) yields fusion of DODAB vesicles, while sodium cholate (NaC) solubilises DODAC to form micelles that fuse into large aggregates [12], SDS increases [11] but NaC decreases [12] the T m of DODAB and DODAC, respectively.…”

Section: Introductionmentioning

confidence: 99%

“…Sodium dodecyl sulphate (SDS) yields fusion of DODAB vesicles, while sodium cholate (NaC) solubilises DODAC to form micelles that fuse into large aggregates [12], SDS increases [11] but NaC decreases [12] the T m of DODAB and DODAC, respectively. Alkyltrimethylammonium salts (C n TAB, n = 12-18) may reduce, increase or leave constant the T m of DODAB, depending on the relative chain length of these surfactants [7,13].…”

Section: Introductionmentioning

confidence: 99%

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Vesicle–micelle transition in aqueous mixtures of the cationic dioctadecyldimethylammonium and octadecyltrimethylammonium bromide surfactants

Alves

Zaniquelli

Loh

et al. 2007

Journal of Colloid and Interface Science

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The vesicle-micelle transition in aqueous mixtures of dioctadecyldimethylammonium and octadecyltrimethylammonium bromide (DODAB and C(18)TAB) cationic surfactants, having respectively double and single chain, was investigated by differential scanning calorimetry (DSC), steady-state fluorescence, dynamic light scattering (DLS) and surface tension. The experiments performed at constant total surfactant concentration, up to 1.0 mM, reveal that these homologous surfactants mix together to form mixed vesicles and/or micelles, depending on the relative amount of the surfactants. The melting temperature T(m) of the mixed DODAB-C(18)TAB vesicles is larger than that for the neat DODAB in water owing to the incorporation of C(18)TAB in the vesicle bilayer. The surface tension decreases sigmoidally with C(18)TAB concentration and the inflection point lies around x(DODAB) approximately 0.4, indicating the onset of micelle formation owing to saturation of DODAB vesicles by C(18)TAB molecules. When x(DODAB)>0.5 C(18)TAB molecules are mainly solubilised by the vesicles, but when x(DODAB)<0.25 micelles are dominant. Fluorescence data of the Nile Red probe incorporated in the system at different surfactant molar fractions indicate the formation of micelle and vesicle structures. These structures have apparent hydrodynamic radius R(H) of about 180 and 500-800 nm, respectively, as obtained by DLS measurements.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Vesicle–micelle transition in aqueous mixtures of the cationic dioctadecyldimethylammonium and octadecyltrimethylammonium bromide surfactants

Alves

Zaniquelli

Loh

et al. 2007

Journal of Colloid and Interface Science

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“…In general, the DSC thermograms of the unsonicated DODAB dispersions are dominated by two endotherms; the pre-and main transition peaks. However, discrepancies are found in the literature for the temperatures at which the pre-(35-36°C), and main (42.7-45°C) transitions occur, although the unsonicated dispersions were prepared by the same method within the concentration range 1-10 mM DODAB [6][7][8][9][10][11][12][13][14]. Nevertheless, the transition temperatures are independent of the concentration as shown in this contribution over a large concentration range 0.5-80 mM DO-DAB.…”

Section: Introductionmentioning

confidence: 82%

“…It includes differential scanning calorimetry [6][7][8][9][10][11][12][13][14], turbidity [14,16], static light scattering [17], fluorescence [9], surface pressure [18], and electron spin resonance (ESR) [10,18,19]. In general, the DSC thermograms of the unsonicated DODAB dispersions are dominated by two endotherms; the pre-and main transition peaks.…”

Section: Introductionmentioning

confidence: 99%

Rheological investigation of thermal transitions in vesicular dispersion

Coppola

Youssry

Nicotera

et al. 2009

Journal of Colloid and Interface Science

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DODAB and DODAC bilayer-like aggregates in the micromolar surfactant concentration domain

et al. 2009

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In the millimolar concentration domain (typically 1 mM), dioctadecyldimethylammonium bromide and chloride (DODAX, X representing Br − or Cl − counterions) molecules assemble in water as large unilamellar vesicles. Differential-scanning calorimetry (DSC) is a suitable technique to obtain the melting temperature (T m) characteristic of surfactant bilayers, while fluorescence spectroscopy detects formation of surfactant aggregates, like bilayers. These two techniques were combined to investigate the assembly of DODAX molecules at micromolar concentrations, from 10 to 100μM. At 1 mM surfactant, T m ≈45°C and 49°C, respectively, for DODAB and DODAC. DSC and fluorescence of Nile Red were used to show the formation of DODAX aggregates, at the surfactant concentration as low as 10μM, whose T m decreases monotonically with increasing DODAX concentration to attain the value for the ordinary vesicles. The data indicate that these aggregates are organized as bilayer-like structures.

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Cited by 14 publications

References 12 publications

Vesicle–micelle transition in aqueous mixtures of the cationic dioctadecyldimethylammonium and octadecyltrimethylammonium bromide surfactants

Vesicle–micelle transition in aqueous mixtures of the cationic dioctadecyldimethylammonium and octadecyltrimethylammonium bromide surfactants

Rheological investigation of thermal transitions in vesicular dispersion

DODAB and DODAC bilayer-like aggregates in the micromolar surfactant concentration domain

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