Biomedical Engineering Reference
In-Depth Information
7.2.1.1.3 Scaffolds
Kothapalli et al. (2005) fabricated a kind of scaffold comprising poly(D,L-
lactic acid) (PLA) and nano-hydroxyapatite (HAp) prepared by using the
solvent-casting/salt-leaching technique. The particles had an average size of
approximately 25 nm in width and 150 nm in length with aspect ratios rang-
ing from 6 to 8. As the HAp content increased in the scaffold from 0 to 50
wt%, the compression modulus of the scaffolds increased from 4.72±1.2 to
9.87±1.8 MPa, while the yield strength increased from 0.29±0.03 to 0.44±0.01
MPa (Kothapalli et al. 2005). Son et al. (2011) reported a combination of a
ceramic/polymer biphasic scaffold. That is, the outside cortical-like shells,
composed of porous HAp with a hollow interior using a polymeric tem-
plate-coating technique and the inner trabecular-like core which consisted
of porous poly(D,L-lactic acid) (PLA) was loaded with dexamethasone (DEX)
and was directly produced using a particle leaching/gas forming technique
to create the inner diameter of the HAp scaffold (Son et al. 2011). Causa et
al. (2006) discovered HAp particles-PCL scaffold has the potential to be an
efficient substrate for bone substitution after the assessment of cell viability,
proliferation, morphology, and ALP. HAp-loaded PCL was found to improve
osteoconduction compared to the PCL alone in the condition of Saos-2 cells
and osteoblasts from human trabecular bone (hOB) retrieved during total
hip replacement surgery seeded onto 3D PCL samples for 1 to 4 weeks (Causa
et al. 2006). Guarino et al. (2008) described a fiber-reinforced composites scaf-
fold composed of poly-L-lactide acid (PLLA) fibers embedded in a porous
poly(epsilon-caprolactone) matrix. The porosity degree can reach 79.7% and
the bimodal pore size distribution is in the range of 10 to 200 µm (Guarino
et al. 2008).
A novel combination of polyurethane (PU) foam method and a hydrogen
peroxide (H
2
O
2
) foaming method is used to fabricate the macroporous HAp
scaffolds. The internal surfaces of the macropores are further coated with a
poly(D,L-lactic-co-glycolic acid) PLGA-bioactive glass composite coating. It
is found that the HAp scaffolds fabricated by the combined method show
high porosities of 61% to 65% and proper macropore sizes of 200 to 600 µm.
The PLGA infiltration improved the compressive strengths of the scaffolds
from 1.5-1.8 to 4.0-5.8 MPa. Furthermore, the bioactive glass-PLGA coatings
rendered a good bioactivity to the composites, evidenced by the formation of
an apatite layer on the sample surfaces immersed in the simulated body fluid
(SBF) for 5 days (Huang and Miao 2007). Xu et al. (2012) compared two kinds
of vascular stents. In this study, vascular stents were fabricated from poly
(lactide-ε-caprolactone)/collagen/nano-hydroxyapatite (PLCL/Col/nHAp)
by electrospinning. In addition, nanocomposite scaffolds of poly (lactic-co-
glycolic acid)/polycaprolactone/nano-hydroxyapatite (PLGA/PCL/nHAp)
loaded with the vascular stents were prepared by thermoforming-particle
leaching and their basic performance and osteogenesis were tested
in vitro
and
in vivo
. The results showed that the PLCL/Col/nHAp stents and PLGA/
Search WWH ::
Custom Search