Biomedical Engineering Reference
In-Depth Information
a
b
c
Fig. 21 (a) Chemical structure of eight-arm PEG-
b
-PLLA-cholesterol. (b) Phase diagram of
eight-arm PEG-
b
-PLLA-choesterol aqueous solution. The photographs indicate the sol (flow) and
gel (no-flow) states of 10 wt% polymer aqueous solution. (c) Eight-arm PEG-
b
-PLLA-cholesterol
hydrogel in tissue culture medium containing live L929 cells. Reprinted from [
320
] with
permission
over a month, after which time the gel was completely dissociated. These results
indicate that the eight-arm PEG-
b
-PLLA-cholesterol can be a candidate as an
injectable cellular scaffold for tissue regeneration.
To obtain biodegradable thermo-gelling system exhibiting even higher mechan-
ical strength, we introduced SC in a hydrogel formation process. As mentioned
above, Kimura et al. already reported a thermo-gelling system using SC formation
on the linear triblock copolymer systems [
313
,
314
]. We synthesized star-shaped
triblock copolymers consisting of eight-arm PEG and PLLA or PDLA, i.e., eight-arm
