Barbieri Thesis - BioMedical Materials program (BMM)

Chapter 3 – Instructive
compos sites: effect of ffiller
content on osteoinduction
unsintereed
apatite is leess
amorphou us than bone apatite becau use it does no ot contain
impuritiess
such as otther
ions (e.g g. carbonate) ), but it is more m amorphous
than
thermally treated apattites.
This conclusion
is suupported
also o by the typic cal X–ray
diffractommeter
patternss
of bone mine eral available in literature, which w peaks are a much
broader thhan
those obsserved
in unsintered
apatitee.
3.3.3. Composites
charracterization
We observed
that apattite
contents exceeding e 50% %wt. led to br rittle composit tes since,
after solvvent
evaporattion,
their bulk
mass pressented
cracks s and could be easily
broken (FFigure
2). Bassing
on these observations, we decided to t use composites
with
0, 10, 20 and 40%wt. aapatite
conten nt for further sttudies
(i.e. 0% % CaP, 10% CaP, C 20%
CaP and 40% CaP resspectively).
Figure 2. Loading poly(D, ,L–lactide) with excessively
high contennt
of apatite, i.e.
more than 50% %wt., led to
brittle compposites.
In the tu ubes, from left to
right, are
the compossites
containing 0%, 0 12.5%, 25% , 30%, 40%,
50% and 755%wt.
apatite content
respectively y. Note that
the materiaals
with 50 to 75%wt. 7 apatite were w brittle
after acetonne
evaporation, and a had many cra acks..
The nano
seen that
composite
observed
or by the
agglomer
(25×) SE
the apati
slightly d
surface m
increase
604 cm –1 o–apatite distribution
in the c
t the apatite pparticles
were
es (Figure 3), , even though
. This might bbe
caused by
solvent evapporation
that m
ration before the complete
M, the blocks of all compos
te amount (FFigure
4). At
different due to the presen
microstructuress
at high apat
in intensity of the character
) with the incrrease
of apatit
main polyylactide
peak ~1100 cm
the polymmer
in the
manufactturing
process
prepared materials (Ta
–1 composites wwas
observed using u BSEM a
e quite homoggeneously
dist tributed throug
h apatite aggloomerates
(2 to
6 m size)
inhomogeneoous
mixing in the ball–millin
may have shiffted
apatite pa articles leadin
hardening off
the polymer r. At low mag
sitions had simmilar
porous structure, s rega
higher magnnification
(10, 000×), they a
nce of apatitee
particles, which w created
ite contents (FFigures
4). FT TIR analysis sh
ristic apatite peeaks
(i.e. ~564–566
cm
te content in thhe
materials w
was w seen demmonstrating
tha
expected tre end (Figure 5). No sign
s on the polymer
moleculaar
weight we
able 4).
–1 and it was
ghout the
could be
g system
g to their
gnification
ardless of
appeared
d rougher
howed an
and
~603–
while a decrea ase of the
at apatite was added to
ificant effects s of the
ere seen in any
of the
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