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Biophysical and lipofection studies of DOTAP analogs.

Biochimica et biophysica acta (2000-03-08)
A E Regelin, S Fankhaenel, L Gürtesch, C Prinz, G von Kiedrowski, U Massing
ABSTRACT

In order to investigate the relationship between lipid structure and liposome-mediated gene transfer, we have studied biophysical parameters and transfection properties of monocationic DOTAP analogs, systematically modified in their non-polar hydrocarbon chains. Stability, size and (by means of anisotropy profiles) membrane fluidity of liposomes and lipoplexes were determined, and lipofection efficiency was tested in a luciferase reporter gene assay. DOTAP analogs were used as single components or combined with a helper lipid, either DOPE or cholesterol. Stability of liposomes was a precondition for formation of temporarily stable lipoplexes. Addition of DOPE or cholesterol improved liposome and lipoplex stability. Transfection efficiencies of lipoplexes based on pure DOTAP analogs could be correlated with stability data and membrane fluidity at transfection temperature. Inclusion of DOPE led to rather uniform transfection and anisotropy profiles, corresponding to lipoplex stability. Cholesterol-containing lipoplexes were generally stable, showing high transfection efficiency at low relative fluidity. Our results demonstrate that the efficiency of gene transfer mediated by monocationic lipids is greatly influenced by lipoplex biophysics due to lipid composition. The measurement of fluorescence anisotropy is an appropriate method to characterize membrane fluidity within a defined system of liposomes or lipoplexes and may be helpful to elucidate structure-activity relationships.

MATERIALS
Product Number
Brand
Product Description

Avanti
18:1 TAP (DOTAP), Avanti Research - A Croda Brand
Avanti
16:0 TAP, Avanti Research - A Croda Brand 890870C
Avanti
18:1 TAP (DOTAP), Avanti Research - A Croda Brand
Avanti
14:0 TAP, Avanti Research - A Croda Brand 890860C
Avanti
14:0 TAP, Avanti Research - A Croda Brand 890860P, powder
Avanti
16:0 TAP, Avanti Research - A Croda Brand 890870P, powder
Avanti
18:0 TAP, Avanti Research - A Croda Brand 890880P, powder
Avanti
18:0 TAP, 1,2-stearoyl-3-trimethylammonium-propane (chloride salt), chloroform