Biomedical Engineering Reference
In-Depth Information
ALP activity was enhanced on the composite PLA/TCP scaffolds compared
to the PLA control particularly by day 18. It was noted that at the highest
β-TCP loading levels of 10 and 20 wt%, there was a dramatic increase in the
amount of cell-mediated mineralization compared to the 5 wt% TCP and
the neat PLA scaffold (McCullen et al. 2009). Yeo et al. (2011) demonstrated
greater degradation of PCL-TCP scaffolds
in vivo
than
in vitro
. At 24 weeks,
the increase of average porosity of the scaffolds
in vivo
was 29.2% compared
to 2.65%
in vitro
. Gel permeation chromatography (GPC) analysis revealed
a decrease of 29% and 20%, respectively, in the Mn and Mw values after
24 weeks
in vitro
. However, a significant decrease in Mn and Mw values
(79.6% and 88.7%, respectively) were recorded
in vivo
. The mechanical prop-
erties closely match those of cancellous bone even at 24 weeks. The results
showed that the scaffold can be used for dentoalveolar reconstruction and
PCL-TCP scaffolds have shown to possess the potential to degrade within
the desired time period of 5 to 6 months and favorable mechanical proper-
ties (Lee et al. 2008). Yeo et al. (2011) fabricated a new hierarchical scaffold
that consisted of a melt-plotted polycaprolactone (PCL)/β-TCP composite
and embedded collagen nanofibers. The fabrication process was combined
with general melt-plotting methods and electrospinning. Scanning electron
microscope (SEM) micrographs of the fabricated scaffolds indicated that the
β-TCP particles were uniformly embedded in PCL struts and that electro-
spun collagen nanofibers (diameter = 160 nm) were well layered between the
composite struts. By accommodating the β-TCP and collagen nanofibers, the
hierarchical composite scaffolds showed dramatic water-absorption ability
(100% increase), increased hydrophilic properties (20%), and good mechani-
cal properties. MTT assay and SEM images of cell-seeded scaffolds showed
that the initial attachment of osteoblast-like cells (MG63) in the hierarchical
scaffold was 2.2 times higher than that on the PCL/β-TCP composite scaf-
fold. Additionally, the proliferation rate of the cells was about 2 times higher
than that of the composite scaffold after 7 days of cell culture (Yeo et al.
2011). Cao and Kuboyama (2010) applied the solvent casting and particulate
leaching method to study composite scaffolds of PGA/beta-TCP (in 1:1 and
1:3 weight ratios) in the repair of critical bone defects (3 mm diameter, 2 mm
depth) in rat femoral medial-epicondyles, compared with HAp and blank
controls. The results showed that the new bone mineral densities (mg/cm
3
)
with HAp, PGA/β-TCP (1:1), and PGA/β-TCP (1:3) at 90 days after surgery
were 390.4±18.1, 563.8±26.9, and 606.3±26.9, respectively. The biodegradation
percents (%) of HAp, PGA/β-TCP (1:1), and PGA/β-TCP (1:3) at 90 days after
surgery were 35.1±-5.5, 99.0±-1.0, and 96.2±-3.3, respectively. The PGA/β-
TCP scaffolds were almost replaced by new growing bone within 90 days
after surgery. Thus, the PGA/β-TCP composite scaffold, especially with a
weight ratio 1:3, exhibited a strong ability for osteogenesis, mineraliza-
tion, and biodegradation for bone replacement (Cao and Kuboyama 2010).
Kim et al. (2012) prepared poly(d,l-lactide:glycolide) (DL-PLGA) and β-TCP
nanocomposites via fused deposition modeling (FDM), a type of extrusion
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