Biomedical Engineering Reference
In-Depth Information
efficacies of the polyion complexes (PICs) as a nanocarrier of siRNA.
146
The
disulfide linkage of the siRNA-grafted polymer allowed efficient siRNA
release from the PICs under reductive conditions in the cytoplasm.
Consequently, the PICs from the siRNA-grafted polymer showed potent
gene-silencing effects without cytotoxicity and immunogenicity.
Dai et al. synthesized a star cationic polymer (s-PDMAEMA) consisting of a
cleavable poly[N,N-bis(acryloyl)cystamine] (PBAC) crosslinked core and
poly(N,N-dimethylethylamine methacrylate) (PDMAEMA) arms by atomic
transfer radical polymerization using a one-pot ''arm first'' method
(Figure 4.11).
147
It was shown that s-PDMAEMA achieved higher gene
transfection levels relative to the linear precursors, and that s-PDMAEMA200
with longer and more arms exhibited superior transfection efficiencies and
lower cytotoxicity compared to 25 kDa PEI. In mild acid milieu the less
contracted condensate was formed between DNA and s-PDMAEMA, with
longer and more arms due to the stretching of the positively charged arm. They
found that star polymers could offer more effective protection of DNA against
DNase
d
n
4
y
3
n
g
|
3
degradation
than
the
linear
counterpart
because
of
the
greater
buffering capability conferred by the unique molecular architecture.
Xiong et al. synthesized a series of cationic fluorine-containing amphiphilic
graft copolymers, P(HFMA-St-MOTAC)-g-PEG, comprising poly(hexafluor-
obutyl methacrylate) (PHFMA), poly(methacryloxyethyl trimethylammonium
chloride) (PMOTAC), polystyrene (PS) backbones, and PEG side chains.
148
The copolymers showed good binding capacity to DNA, and could be used as
a promising nonviral vector.
Figure 4.11
pH-dependent morphological change of PDMAEMA/DNA complexes.
