Biomedical Engineering Reference
In-Depth Information
proliferation of osteoblasts and mesenchymal cells, bone tissue
ingrowth,vascularinvasion,nutrientdelivery,andmatrixdeposition
inemptyspaces.Infact,themaincriticalfactoraffectingboneforma-
tion is the presence of a combined macro- and microporosity, since
macropores (size
>
100
μ
m) have a critical impact on osteogenic
outcomes, promotion of vascularization, and mass transportation
of nutrients and waste products,
4
while micropores (size around
10
μ
m)favorcapillaryformation.Currently,itiscommonlyaccepted
that3Dscaffoldsshouldalsocontainnanoporositytoallowdiffusion
of molecules fornutrition and signaling.
2
Poreinterconnectionalsoplaysakeyroleintheoverallbiological
system,sinceitprovidesthechannelforcelldistributionandmigra-
tion, allowing e
cient
in vivo
blood vessel formation. Furthermore,
porewallroughnesscontributestoincreasethesurfacearea,protein
adsorption, and ion exchange.
1
,
3
Following these considerations, efforts should be addressed to
the development of synthetic biomaterials that tailor the remark-
ablebiomechanicalpropertiesandhierarchicalstructureofbonetis-
sue as an organized assembly of structural units at increasing size
levels that provide optimum fluid transfer and self-healing.
6
Open
structure-based scaffolds with appropriate pore size, interconnec-
tivity, and total porosity should be modeled and developed in order
toprovide
in vivo
bloodvesselinvasionandneobonetissueingrowth
within the scaffolds.
The new generation of biomaterials for use as scaffolds for
bone tissue engineering and regenerative medicine applications
should mimic the smart structures present in nature. Computer-
assisted design and rapid prototyping techniques may be used to
generate intelligent scaffolds with defined architecture. Neverthe-
less, bioderived materials represent an exciting approach since they
take advantage of the knowledge and perfection of materials devel-
oped by evolution over millions of years and they take inspiration
from the most complex naturally organised chemical and biological
structures.
Recently, in this context, bioinspired SiC ceramics obtained from
vegetable structures, as different woods and plants, have been a
matter of interest.
7
−
12
This innovative biomaterial is produced by
molten Si infiltration of carbon templates obtained by controlled
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