SUPRAMOLECULAR ASSEMBLIES |
Polymorphism of Pyridinium Amphiphiles for Gene Delivery:
Influence of Ionic Strength, Helper Lipid Content and
Plasmid DNA Complexation
Marco Scarzello 1, Vladimir Chupin 2, Anno Wagenaar 1, Marc C.A. Stuart 1, Jan B.F.N. Engberts 1* and Ron Hulst 3
1 University of Groningen-OMAC
2 University of Groningen -OMAC
3 Kiadis BV
* To whom correspondence should be addressed. E-mail: j.b.f.n.engberts{at}chem.rug.nl.
Submitted on October 11, 2004
Revised on November 19, 2004
Accepted on 14 December 2004
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Abstract |
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Two double tailed pyridinium cationic amphiphiles, differing only in the degree of unsaturation of the alkyl chains, have been selected for a detailed study of their aggregation behaviour, under conditions as employed for transfection experiments. The transfection efficiencies of the two molecules are remarkably different, especially when combined with DOPE as helper lipid. The phase behaviour of the cationic amphiphile/DOPE mixtures have been studied using 31P- and 2H-NMR (on deuterated cationic amphiphiles) as main techniques, in order to monitor independently the behaviour of the two components. In water, the lamellar organization is dominant for both the surfactants in their mixtures with the helper lipid. In HBS, the mixtures of the unsaturated surfactant form inverted phases and, in particular, stable HII phases for DOPE contents equal or higher than 30 mol%. By contrast, the saturated surfactant does not form homogeneously mixed inverted phases in mixtures with DOPE at room temperature. However, mixed inverted phases are observed for this system at higher temperatures and, after mixing has been achieved by heating, the metastable mixed phases remain present for several hours at 5°C. At 35°C the dominant phase is the cubic phase. The lipoplex composed of equimolar mixtures of the unsaturated surfactant with DOPE and plasmid DNA was found to be organized in highly curved bilayers.
Key Words:
H2-NMR, P31-NMR, cationic amphiphiles, cryo-TEM, gene therapy, lipoplex
