Biomedical Engineering Reference
In-Depth Information
the nanocomposites as compared to those on pure PLA. Moreover, the min-
eralized product by the cells was observed to be significantly higher on the
nanocomposites with respect to pure PLA. The newly developed nanocom-
posite constituted of bioactive nanofiber and degradable polymer is consid-
ered as a promising bone regeneration matrix with its excellent bioactivity
and osteoblast response (Kim et al. 2008).
7.2.2.2 Microspheres
Lei et al. (2012) examined the utility of sol-gel-derived bioactive glass micro-
spheres (BGMs) as a reinforcement to improve the mechanical properties
and biological performance of poly(ε-caprolactone) (PCL) polymer. All of the
PCL-BGMs composites produced, with a variety of BGM contents (10, 20, and
30 wt%), showed a uniform distribution of the BGMs in the PCL matrix, par-
ticularly owing to their spherical shape and small size. This led to a consid-
erable increase in the elastic modulus from 93±12 MPa to 635±179 MPa with
increasing BGMs content from 0 to 30 wt%. Furthermore, the addition of the
BGMs to the PCL polymer significantly increased the hydrophilicity of the
PCL-BGMs composites, leading to a higher water absorption and degrada-
tion rate. The PCL-BGMs composite with a BGMs content of 30 wt% showed
vigorous growth of apatite crystals with a high aspect ratio on its surface
after soaking in the simulated body fluid for 7 days, resulting in the creation
of a porous carbonate hydroxyapatite layer (Lei et al. 2012).
7.2.2.3 Scaffolds
Wu, Zhang, Zhu, et al. (2010) investigated the effects that blending silk incor-
porated into MBG on the physiochemical, drug delivery, and biological
properties of MBG scaffolds. The results showed that the uniformity and
continuity of the pore network of MBG/silk composites improved, and high
porosity (94%) and large pore size (200-400 mm) maintained. The mechani-
cal strength, mechanical stability, and control of burst release of DEX in
silk-modified MBG scaffolds reached a great increase. Silk modification also
appeared to provide a better environment for BMSC attachment, spread-
ing, proliferation, and osteogenic differentiation on MBG/silk composites
(Figure 7.5) (Wu, Zhang, Zhu, et al. 2010).
Wu, Zhang, Zhou, et al. (2011) used a freeze-drying method to incorporate
MBG into silk scaffolds in order to improve their osteoconductivity and then
to compare the effect of MBG and BG on the in vivo osteogenesis of silk scaf-
folds. The scaffolds were implanted into calvarial defects in SCID mice. The
results showed that MBG/silk scaffolds have better physiochemical proper-
ties (mechanical strength, in vitro apatite mineralization, Si ion release, and
pH stability) compared to BG/silk scaffolds. MBG and BG both improved
the in vivo osteogenesis of silk scaffolds. lCT and HE analyses showed that
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