Biomedical Engineering Reference
In-Depth Information
1.2.2.3 Hydroxyapatite
Coral-derived apatite is a natural substance made by marine
vertebrates.
11
The porous structure of coral is its unique physico-
chemical property for the scaffold matrix as bone substitutes due
to the structural similarity to bone. The main component of natural
coral is calcium carbonate or aragonite, the metastable form of cal-
cium carbonate, and it also can be converted to hydroxyapatite by a
hydrothermal exchange process, resulting in the mixture of hydrox-
yapatite, 9CaO
·
Ca(OH)
2
·
3P
2
O
5
, and fluoroapatite, Ca
5
(PO
4
)
3
F. For
the tissue-engineered bone, the hybrid structure of porous coral-
derived scaffold and mesenchymal stem cell were demonstrated
in vitro
. This result showed the differentiation of bone marrow-
derived stem cell to osteoblast, and successive mineralization was
successfully accomplished.
1.2.2.4 Bioglass
Glass ceramics are polycrystalline ceramics manufactured by con-
trolled crystallization of glasses using nucleating agents such as
small amounts of metallic agents Pt groups, TiO
2
,ZrO
2
,andP
2
O
5
,
resultinginafine-grainedceramicthatpossessesexcellentmechani-
calandthermalproperties.
9
Typicalbioglassceramicsdevelopedfor
implantations are SiO
2
-CaO-Na
2
O-P
2
O
5
and Li
2
O-ZnO-SiO
2
systems.
These bioglass scaffolds are suitable for the regeneration of induc-
ing direct bonding with bone. The bonding to bone is related to the
composition of each component.
1.2.2.5 Demineralized bone particle
One of the significant natural bioactive materials is DBP, which is a
powerfulinducerofnewbonegrowth.
12
Ithasbeenrecognizedthat
DBPcontainsmanykindsofosteogenicandchondrogeniccytokines
as bone morphogenetic protein and widely uses a filling agent for
bony defects in the clinic due to improved availability through the
growingtissuebankindustry.Fortheoptimizationoftheapplication
ofDBPtotissueengineering,researchstudiessuchasnanohybrdiza-
tionwithsynthetic(PLGA/DBPhybridscaffolds)andnaturalorganic
compounds (collagen/DBP hybrid scaffolds) have been done.
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