Biomedical Engineering Reference
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out structure-activity relationship studies by placing the disulfide
bridge at different positions in the backbone of the cationic lipid and
by systematic variation of the lipid chain length and nature. Results
indicate that transfection levels can be modulated as a function of
the location of the disulfide bridge in the molecule (see Figs. 1.12
and 1.14).
A
r
r
o
w
s
i
n
d
i
c
a
t
e
t
h
e
s
i
t
e
s
w
h
e
r
e
d
i
s
u
l
f
i
d
e
b
r
i
d
g
e
s
c
a
n
b
e
i
n
t
r
o
d
u
c
e
d
i
n
l
i
p
o
p
o
l
y
a
m
i
n
e
s
Figure 1.1
Structure-activity relationship studies on reduction sensitive
lipopolyamines.
The synthesis is based on a convergent approach. In the first step,
building blocks 1, 2, and 3 were prepared as described in Fig. 1.13.
O
O
H
+
O
N
S
S
H
H
O
S
N
O
H
Excess
O
DMF/TEA
Scaffold for linker position
H
S
O
H
N
S
O
O
O
1
Scaffold for lipid position
Scaffold for side chain
and lipid positions
O
O
R
O
D
MF/TE
A
O
S
S
N
+
R
S
H
O
H
S
S
O
H
N
H
O
O
Excess
N
O
O
O
O
3
2
Figure 1.1
Synthesis
of
reduction-sensitive-lipopolyamine
building
blocks.
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