Biomedical Engineering Reference
In-Depth Information
17.3 A schematic representation of a biomineralization process on
PLLA/ND-ODA scaffolds in SBF. (1) The initial stage. (2) While in contact
with SBF, PLLA is hydrolyzed, resulting in the formation of -COOH
groups on the surface of the scaffold. Due to the degradation of PLLA,
ND-ODA is exposed to SBF. The exposed -COOH groups of ND-ODA
dissociate and form negatively charged -COO- on the surface. In
addition, the ND-ODA may speed up the degradation of PLLA to
produce more -COOH groups on the PLLA surface. The negatively
charged surface attracts Ca 2+ . (3) The deposited calcium ions, in turn,
interact with phosphate ions in the SBF and form bonelike apatite. (4)
The bonelike apatite then grows spontaneously, consuming the calcium
and phosphate ions to form apatite clusters. Reprinted with permission
from Elsevier (Zhang et al., 2012).
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In a very recent work, Zhang et al. (2012) prepared multifunctional bone
scaffold materials composed of PLLA and octadecylamine-functionalized
ND (ND-ODA) via solution casting followed by compression molding.
Addition of 10 wt% of ND-ODA resulted in a 280% increase in the strain to
failure and a 310% increase in fracture energy as compared to neat PLLA.
Both of these parameters are crucial for bone tissue engineering and for the
manufacture of orthopedic surgical fixation devices. The biomineralization
of nanocomposite scaffolds in simulated body fluid (SBF) (Kokubo and
Takadama, 2006) was tested. Apatite nucleation and growth occurred more
quickly on nanocomposites than on neat PLLA (Fig 17.3) (Zhang et al.,
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