Biomedical Engineering Reference
In-Depth Information
Table 8
(continued)
D. Disulfide containing lipids
O
O
O
O
O
S
S
O
O
O
O
O
NH
3
+
2CF
3
CO
2
-
DOGSDSO
NH
3
+
O
H
N
NH
3
+
S
S
O
N
O
2CF
3
CO
2
-
CHDTAEA
NH
3
+
O
O
S
S
N
S
S
O
CH
3
SO
3
-
O
AP1
4.1
Gene Delivery Via Vationic Liposomes
Cationic lipids are generally formulated into cationic liposomes (CL) that can elec-
trostatically and hydrophobically interact with anionic nucleic acids like pDNA and
siRNA to form lipoplexes (Wong et al.
1996
). Factors such as the lipid structure,
the lipid composition of liposomes, the preparation procedure of liposomes, the
kinetics of mixing for the preparation of lipoplexes, the lipid/nucleic acid ratio, and
the size of nucleic acid, have been found to dominate the physicochemical charac-
ters of the resulting lipoplexes (Dass and Su
2000
), which in turn may affect the
transfection efficiency. Among them, the chemical structure of lipids is one of the
most important factors that strongly affect both transfection activity and cytotoxic-
ity of lipoplexes. Extensive studies on triester phosphatidylcholines (PCs) indicate
a strong, systematic dependence of their transfection efficiency on the lipid hydro-
carbon chain. It has been shown that transfection activity increases with the increase
in chain unsaturation from 0 to 2 double bonds per lipid and decreases with increase
of chain length in the range ~30-50 total number of chain carbon atoms (Koynova
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