Biomedical Engineering Reference
In-Depth Information
Figure 27.1.
Chemical synthesis and
1
H-NMR spectrum of PLCL (50:50).
whilethemethyleneprotonsofthecaproylunitadjacenttotheester
group appear at
2.3-2.5 (g, g'). The copolymer
compositions synthesized by these relative intensities almost iden-
tically correspond to the initial feed compositions. PLCL prepared
from 50 wt% of
L
-lactide and 50 wt% of
δ
4.0-4.2 (c, c') and
δ
ε
-caprolactone is highly
elastic and has been fabricated for microporous scaffolds using a
variety of techniques such as extrusion-particulate leaching, gel
spinning, gel pressing, freeze drying, and electrospinning. The
mechanical properties of PLCL scaffolds were measured and com-
pared with those of PLGA scaffolds; PLCL scaffolds fabricated with
60% porosity exhibit a strain of 500%, and scaffolds of 90% poros-
itycanbeextendedto200%.PLCLscaffoldswith90%porosityshow
100% recovery at near-100% strain. In addition, PLCL scaffolds can
beeasilytwistedandbent.Incontrast,PLGAscaffoldslargelydeform
and are broken even at strains as low as 20%. To further exam-
ine the elastic properties of PLCL scaffolds, scaffolds with varying
porosity were subjected to cyclic strain at 10% amplitude and 1 Hz
frequency for 27 days in a culture medium.
19
PLCL scaffolds of all
tested porosities maintain excellent elasticity even in the hydrolytic
medium over a 27-day experimental time course. Degradation tests
show that the degradation rate of PLCL scaffolds is somewhat faster
in vivo
than
in vitro
, and this may be explained by enzymatic degra-
dationpossiblyplayingaroleindegradationinthebody.Inaddition,
the CL moieties degrade faster than the LA units in PLCL scaffolds,
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