Biomedical Engineering Reference
In-Depth Information
physiological pH of 7.4), poor stability of the polyplex at physiological pH,
low cell specificity, and low transfection efficiency, which need to be overcome
before its use in clinical trials.
4.3.1 PEI-Modified Chitosans
In order to improve the transfection efficiency of chitosan, many efforts have
been made and various modifications have been carried out. For example, Gao
et al. linked chitosan with 1.8 kDa PEI by 1,19-carbonyldiimidazole to form a
chitosan-linked PEI copolymer (Scheme 4.5A).
53
In HepG2, A549, and HeLa
cells, this compound exhibited lower cytotoxicity and better long-term
transfection ability compared with 25 kDa PEI. Furthermore, it was used as
a gene carrier to deliver the therapeutic gene CCL22 into peripheral hepatoma
cells (H22). When these gene-altered cells were inoculated in mice, the tumor
growth rate was significantly decreased. Ping et al. synthesized water-soluble
chitosan-g-(PEI-b-CD) cationic copolymers via reductive amination between
oxidized
d
n
4
y
3
n
g
|
3
chitosan
and
LMW
PEI
(423
Da,
600
Da)-modified b-CD
Scheme 4.5
Synthesis of PEI-modified chitosans.
