TABLE 2.

Composition of lipoplexes prepared from DOTIM/DOPE (1:1) liposomes after sedimentation in sucrose density gradients

				DOTIM	DNA
Lipoplex	Mixing ratio (+/−)	Fraction	Cumulative volume, ml	% of total		Final ratio* (+/−)
SUV	3.6 ± 0.2	1	0.13 ± 0.02	16.3 ± 1.8	0.9 ± 0.3	2.1 ± 0.08
		2	0.42 ± 0.03	15.2 ± 0.8	1.4 ± 0.3
		3	1.35 ± 0.03	11.8 ± 3.3	16.7 ± 4.1
		4	2.45 ± 0.08	41.0 ± 2.8	72.6 ± 1.5
sMLV	3.8 ± 0.5	1	0.15 ± 0.01	5.5 ± 0.8	1.2 ± 0.2	3.4 ± 0.33
		2	0.69 ± 0.02	11.8 ± 4.4	5.3 ± 2.4
		3	1.55 ± 0.03	45.5 ± 5.7	49.9 ± 5.0
		4	2.32 ± 0.07	20.1 ± 2.1	31.7 ± 4.7

Cationic lipoplexes were prepared from either SUV or sMLV at the (+/−) ratios indicated in the table, and sedimented at 116,000 × g for 16 h, at 10°C. After sedimentation, the gradient was fractionated by collecting fractions from the top of the tubes, and the volume of each fraction was recorded. DOTIM and DNA content was determined in each fraction as described under Materials and Methods. Results are mean values of three determinations ± standard deviations. The total recovery of DOTIM and DNA in all the fractions was usually >85%.

^*(+/−) ratios were calculated taking into consideration that 1 nmol DOTIM contains 1 nmol positive charge and 1 μg DNA is 3 nmol negatively charged phosphate.