Biomedical Engineering Reference
In-Depth Information
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Figure 9.8
Schematic
illustration
of
the
formation
of
crosslinked
micelles
and
intracellular
drug
release
and
synthetic
pathway
of
the
triblock
copolymer PCL-b-PPE
SH
-b-PEG.
13
with CA as the core, the interlayer of PAsp(DIP) as the pH-sensitive shell, and
PEG as the corona. The hydrophobic drug PTX was encapsulated into the
micelle core while negatively charged quantum dots (QDs) were embedded in
the shell layer as a fluorescent imaging probe for identifying tumor location.
The pH-sensitive interlayer acted as an ''on-off'' module to turn the drug
release ''off'' at neutral pH (e.g. in blood circulation) but ''on'' in the acidic
lysosomal compartments (pH
#
5.0) of cells. Folic acid was used to
functionalize the micelle for active tumor targeting, based on the fact that
the folate receptor (FR) is overexpressed in many cancer cells yet rarely found
in normal cells. Cell and animal studies revealed great potential for this unique
micelle design in drug delivery applications.
A recent advance in nanomedicine-mediated cancer therapy is the
development of multifunctional carriers for jointly delivering a chemother-
apeutic drug and genetic material such as pDNA or siRNA.
15
Shuai et al.
16
developed CSC micelles as biodegradable nano-carriers for co-delivery of
BCL-2 siRNA and DOX, as shown in Figure 9.10. An amphiphilic diblock
copolymer of poly(e-caprolactone)-block-poly(ethylenimine) (PCL-b-PEI) was
