Biodegradable PHBV Polymer-Based Scaffolds for Bone Tissue Engineering - Biodegradable Polymer-Based Scaffolds for Bone Tissue Engineering - page 50

Fig. 3.7 An EDX spectrum confirming the presence of HA nanoparticles in HA/PHBV
composite scaffold
Good distribution and good adhesion of HA nanoparticles in the porous PHBV
matrix were found according to SEM and EDX analyses of scaffolds. Using the
same processing parameters, the HA/PHBV composite scaffolds fabricated pos-
sessed nearly the same porous morphology (Fig. 3.6 b) as that of pure PHBV scaf-
folds. At low contents (5-10 %) of HA, HA/PHBV scaffolds maintained internal
ladder-like pore structure which was similar to that of PHBV scaffolds. It was
found that HA nanoparticles were mostly distributed within the pore walls of scaf-
folds. At high contents (>10 %) of HA, some aggregates of HA particles appeared
on pore surfaces. Compared to PHBV scaffolds, with the incorporation of HA nan-
oparticles, the pore size of composite scaffolds decreased slightly and the scaffolds
exhibited both open and closed pore morphology. The freeze-dried HA powders
used in this investigation consisted of tiny agglomerates of HA nanocrystallites,
and from SEM micrographs in Fig. 3.6 b, it can be seen that a small percentage of
HA nanoparticles existed on the surface of pore walls. Fibrous and loose network
of semicrystalline PHBV polymer could be seen at high magnifications and HA
nanoparticles were observed to adhere to polymer fibrils. EDX analyses at differ-
ent locations of composite scaffolds confirmed the presence of HA particles inside
pore walls (Fig. 3.7 ). Figure 3.8 shows the TGA traces of pure PHBV scaffolds
and 10 % HA incorporated PHBV scaffolds in terms of weight loss as a function
of temperature. It was observed that at 10 wt % nHA concentration, nHA parti-
cles were distributed homogeneously within the pore walls of the scaffolds. No
significant agglomeration of HA nanoparicles was occurred within the pore walls.
Figure 3.6 b shows the nHA/PHBV scaffold with the nHA content of 10 wt %.
It can be seen from Fig. 3.9 that there was a ten-fold increase in compres-
sive modulus when the polymer solution concentration was changed from 5 to
10 % (w/v). The compressive curves of PHBV and HA/PHBV scaffolds dis-
played in Fig. 3.9 indicated that the scaffolds underwent three distinctive stages
of deformation, with HA/PHBV scaffolds exhibiting a higher level of resistance