Temperature quenched DODAB dispersions: Fluid and solid state coexistence and complex formation with oppositely charged surfactant
(2004) In Langmuir 20(10). p.3906-3912- Abstract
- Dilute dispersions of the synthetic bilayer forming double-chained cationic lipid dioctadecyldimethylammonium bromide (DODAB) were investigated. In dispersions sonicated above the chain melting temperature T-m (approximate to45 degreesC) it was found by H NMR that about 50% of the surfactant chains remained fluid when the samples were cooled to room temperature, which is 20 degreesC below T-m. In contrast, there was no sign of a fluid fraction in unsonicated samples at room temperature. The addition of the anionic surfactant sodium dodecyl sulfate (SDS) to DODAB dispersions at room temperature resulted in the formation of an essentially stoichiometric DODA-DS complex with frozen chains, as seen by titration calorimetry and H NMR... (More)
- Dilute dispersions of the synthetic bilayer forming double-chained cationic lipid dioctadecyldimethylammonium bromide (DODAB) were investigated. In dispersions sonicated above the chain melting temperature T-m (approximate to45 degreesC) it was found by H NMR that about 50% of the surfactant chains remained fluid when the samples were cooled to room temperature, which is 20 degreesC below T-m. In contrast, there was no sign of a fluid fraction in unsonicated samples at room temperature. The addition of the anionic surfactant sodium dodecyl sulfate (SDS) to DODAB dispersions at room temperature resulted in the formation of an essentially stoichiometric DODA-DS complex with frozen chains, as seen by titration calorimetry and H NMR experiments. For sonicated samples, turbidity experiments demonstrated that, after a fast complexation reaction, the system remains colloidally stable unless the SDS-to-DODAB mixing ratio is too close to unity. H NMR experiments also showed that in the unreacted DODAB the fraction of fluid chains remained close to 50%, indicating either that SDS reacts equally fast with fluid and frozen DODAB or that there is a relaxation of the fluid fraction after the complexation. The melting enthalpy and the melting temperature of the alkyl chains rise gradually as the mixing ratio increases. We observed with cryo-TEM that the fraction of large unilamellar vesicles was significantly larger after addition of SDS. This indicates vesicle fusion. Based on both wide- and small-angle X-ray scattering patterns, the structure of the equimolar SDS-DODAB complex at 25 degreesC was proposed to be lamellar. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/153860
- author
- Cocquyt, J ; Olsson, Ulf LU ; Olofsson, Gerd LU and Van der Meeren, P
- organization
- publishing date
- 2004
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Langmuir
- volume
- 20
- issue
- 10
- pages
- 3906 - 3912
- publisher
- The American Chemical Society (ACS)
- external identifiers
-
- pmid:15969378
- wos:000221319400017
- scopus:2542463852
- ISSN
- 0743-7463
- DOI
- 10.1021/la036080c
- language
- English
- LU publication?
- yes
- id
- 14dd033f-1b7d-4238-9e39-de461f0fab4b (old id 153860)
- date added to LUP
- 2016-04-01 11:39:05
- date last changed
- 2022-03-12 22:39:24
@article{14dd033f-1b7d-4238-9e39-de461f0fab4b,
abstract = {{Dilute dispersions of the synthetic bilayer forming double-chained cationic lipid dioctadecyldimethylammonium bromide (DODAB) were investigated. In dispersions sonicated above the chain melting temperature T-m (approximate to45 degreesC) it was found by H NMR that about 50% of the surfactant chains remained fluid when the samples were cooled to room temperature, which is 20 degreesC below T-m. In contrast, there was no sign of a fluid fraction in unsonicated samples at room temperature. The addition of the anionic surfactant sodium dodecyl sulfate (SDS) to DODAB dispersions at room temperature resulted in the formation of an essentially stoichiometric DODA-DS complex with frozen chains, as seen by titration calorimetry and H NMR experiments. For sonicated samples, turbidity experiments demonstrated that, after a fast complexation reaction, the system remains colloidally stable unless the SDS-to-DODAB mixing ratio is too close to unity. H NMR experiments also showed that in the unreacted DODAB the fraction of fluid chains remained close to 50%, indicating either that SDS reacts equally fast with fluid and frozen DODAB or that there is a relaxation of the fluid fraction after the complexation. The melting enthalpy and the melting temperature of the alkyl chains rise gradually as the mixing ratio increases. We observed with cryo-TEM that the fraction of large unilamellar vesicles was significantly larger after addition of SDS. This indicates vesicle fusion. Based on both wide- and small-angle X-ray scattering patterns, the structure of the equimolar SDS-DODAB complex at 25 degreesC was proposed to be lamellar.}},
author = {{Cocquyt, J and Olsson, Ulf and Olofsson, Gerd and Van der Meeren, P}},
issn = {{0743-7463}},
language = {{eng}},
number = {{10}},
pages = {{3906--3912}},
publisher = {{The American Chemical Society (ACS)}},
series = {{Langmuir}},
title = {{Temperature quenched DODAB dispersions: Fluid and solid state coexistence and complex formation with oppositely charged surfactant}},
url = {{http://dx.doi.org/10.1021/la036080c}},
doi = {{10.1021/la036080c}},
volume = {{20}},
year = {{2004}},
}