Biomedical Engineering Reference
In-Depth Information
chemistry)
122,123,124
while inflammation is linked to the process of angiogen-
esis,
125
which is necessary for the adequate vascularization of scaffolds after
implantation into the host tissue.
122
Bone tissue engineering scaffolds must pro-
vide an osteoconductive surface to promote new bone ingrowth after implanta-
tion into bone defects that may be achieved by HA loading of distinct scaffold
biomaterials. Lashke et al. reported the in vitro and in vivo properties of a novel
nanosize hydroxyapatite particles/poly(ester-urethane) (nHA/PU) composite
scaffold which was prepared by a salt leaching-phase inverse process.
122
Analy-
sis of results with microtomography, SEM, and X-ray spectroscopy demonstrated
the capability of the material processing to create a three-dimensional (3D)
porous PU scaffold with nHA on the surface. The modified scaffold induced a
significant increase in in vitro adsorption of model proteins compared to nHA-
free PU scaffolds (control).
122
In vivo analysis of inflammatory and angiogenic
host tissue response to implanted nHA/PU scaffolds indicated that the nHA par-
ticles incorporation into the scaffold material did not affect biocompatibility and
vascularization.
122
Biodegradable nHA/PU composite scaffold that was fabricated by a salt
leaching-phase inverse process had been developed for bone regeneration.
122,126
The addition of 10-20%
w
of nHA improved the scaffold stiffness with an increase
of 50% in the Young modulus, which may result in better scaffold stability after
implantation into a bone defect.
122
In addition, the osteoconductive properties of
the calcium phosphate-containing scaffold surface may accelerate and improve
the formation of new bone tissue within the biodegradable PU foam.
122
Nanohydroxyapatite (n-HAP) reinforced ceramic/polymer nanocompos-
ites have gained recognition as bone scaffolds due to their composition and
structural similarity with natural bones.
127
In addition, their unique functional
properties such as larger surface area and superior mechanical strength make
them better than those of their single-phase constituents. Rod-shaped n-HAP
nanocomposite scaffold has been developed to mimic natural bone apatite mor-
phology.
128
Incorporation of synthesized nHA in place of microparticles of
HA brings higher mechanical strength and more regular microarchitecture that
result from the nanoparticles' interfacial area, surface reactivity, and ultrafine
structure. A variety of scaffolds using thermally have also been reported for
thermally induced phase separation.
129,130
In one study, n-HAP bone scaffolds were prepared by a homemade selec-
tive laser sintering (SLS) system based on rapid prototyping technology.
131
The SLS system developed consisted of a precise three-axis motion platform
and a laser with optical focusing device which implements arbitrary complex
movements based on the nonuniform rational B-spline theory is realized in this
system. The effects of the processing parameters on n-HAP were tested with
X-ray diffraction, Fourier transform infrared spectroscopy, and SEM. The par-
ticles of n-HAP grew into spherical like from the initial needle-like shape with
a nanoscale structure at scanning speeds between 200- and 300-mm/min when
the laser power was 50W, the light spot diameter 4mm, and the layer thickness
