Biomedical Engineering Reference
In-Depth Information
d
n
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3
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Figure 6.6
Schematic presentation of pH-sensitive biodegradable chimaeric poly-
mersomes based on an asymmetric PEG-PTTMA-PAA triblock copoly-
mer. (Reproduced from Du et al.
42
with permission from Elsevier.)
efficient loading of the hydrophilic anticancer drug DOX?HCl. The PTTMA
block triggered efficient intracellular release and high cytotoxicity of DOX?HCl
(IC
50
close to that of free DOX?HCl) due to rapid hydrolysis of the acetal groups
of PTTMA at mildly acidic pH (Figure 6.6).
42
Armes, Ryan and co-workers
have reported the formation of asymmetric polymersomes from PEO-PDPA-
poly[2-(dimethylamino)ethyl
methacrylate]
(PEO-PDPA-PDMA)
triblock
copolymers in aqueous solution.
43
Jin et al. have reported fabrication of asymmetric polymersomes from PEG-
b-PCL and dextran-b-PCL (DEX-b-PCL) by ''phase-guided assembly'' in
which DEX-b-PCL formed the inner leaflet around the dispersed dextran
phase and PEG-b-PCL formed the outer leaflet with the PEG block facing the
PEG continuous phase (Figure 6.7).
44
These asymmetric polymersomes could
encapsulate erythropoietin with high efficiency. Li et al. prepared asymmetric
polymersomes from a mixture of PEG-b-PBD and the UV-sensitive liquid-
crystalline copolymer PEG-b-PMAzo, which upon UV illumination resulted in
instantaneous bursting of the polymersomes.
45
6.4 Biomimetic Polymersomes
Polymersomes spanning from nano to micro scales provide an ideal technology
platform
for
mimicking
viruses,
cell
organelles,
and
cells.
Choi
and
