Biomedical Engineering Reference
In-Depth Information
transfection efficiency while exhibiting substantially lower toxicity in comparison
with 25 kDa PEI. Moreover, the flanking primary amine groups induced by ED
could be readily functionalized by glycyrrhetinic acid or cholic acid to improve
the biophysical properties of the gene vectors.
Dong et al. synthesized a series of biodegradable cationic polymers,
poly(ethylene glycol)-block-poly(carbonates-graft-oligoethylenimine) [mPEG-
b-P(MCC-g-OEI), PPO] copolymers.
131
Different kinds of OEI were grafting
onto the mPEG-b-PMCC backbone, such as linear OEI423, branched OEI600,
and branched OEI1800. The cell toxicity and gene transfection evaluations
showed that PPO copolymers, especially PPO1800, exhibited lower cytotoxi-
city and about three times higher gene transfection efficiency than 25 kDa PEI,
both in the absence and presence of serum in the CHO and COS-7 cell lines.
Miyata et al. demonstrated that the silica-coated polyplexes could be
prepared using a silicic acid condensation reaction for enhanced polyplex
stability and transfection activity through shielding of the cationic surface
charge (Figure 4.10).
132
The silica-coated polyplex achieved significantly
higher transfection efficiency without serious cytotoxicity compared to the
polyplex without any silica coating, possibly due to their facilitated endosomal
escape.
Zhang and co-workers synthesized folate-PEG modified poly[2-(2-ami-
noethoxy)ethoxy]phosphazene (folate-PEG-PAEP) as a folate receptor (FR)
targeted carrier.
133
Compared with the unmodified nanoparticles, the
cytotoxicity of folate-PEG-PAEP decreased significantly at high dose. They
also showed much higher transfection efficiency in FR overexpressing HeLa
cells, but no significant difference was observed in CHO-k1 cells lacking FR.
d
n
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y
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n
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Figure 4.10
Preparation of silica-coated polyplexes.
