Figure 1.

Gel electrophoresis of pCMV‐Luc+ after an exchange reaction of the plasmid DNA complexed with liposome or emulsion by heparin or lung surfactant in the absence (A) and presence of DNase I (B). Lipid carrier/DNA complexes were prepared by mixing pCMV‐Luc+ with LP1 (lanes 3–5) or LE1 (lanes 6–8) at C/D = 4 in 20 µl PBS. The formed complexes were incubated for 1 h at room temperature with 50 equivalency of heparin solutions (lanes 4 and 7) or 5 µg of lung surfactant (lanes 5 and 8). After the incubation, samples were analyzed by gel electrophoresis (A). The heparin or lung surfactant treated carrier/DNA complexes as well as naked DNA were incubated with 0.5 U/ml of DNase I for 10 min at 37 °C. DNAs in the complexes were extracted with phenol/chloroform/isoamyl alcohol (50 : 49 : 1 by volume) and were analyzed by gel electrophoresis. M: DNA molecular marker (λ Hind III); lane 1: 1 µg of DNA (no treatment); lane 2: 1 µg of DNA (treated with DNase I); lanes 3–5: LP1/DNA complexes; lanes 6–8: LE1/DNA complexes