Biomedical Engineering Reference
In-Depth Information
outlines future directions and discusses the perspectives of simulation in
biomineralisation studies (Zahn
et al
., 2007).
these studies may soon be fundamental to obtaining highly controlled
methods of fabrication of scaffolds for tissue engineering (see Section 14.5).
Computational models needs to be underpinned by the background information
available in the literature that offers insights into the structure, self-assembly
mechanisms and properties of mineralised collagen fibril composites (Robey,
1996, Olszta
et al
., 2007).
Types of polymer/ceramic composites for bone tissue engineering
and their fabrication methods
thus far, all the polymeric and ceramic materials described in the previous
sections have been employed in an attempt to produce composite biomaterials
able to mimic bone structures. above all, collagen/Ha composites have been
designed because of their close proximity to the bone chemical composition.
Investigation and simulation of the collagen fibril structures has presented
the knowledge platform for developing bone grafts or for their use as bone
biomimetic engineering materials and scaffolds in bone tissue engineering.
indeed, the development of bone grafts based on the mineralisation of self-
assembled collagen fibrils
in vivo
and
in vitro
is an active area of research
(Cui
et al
., 2007b).
as a collagen denaturation derivative, gelatin matrix composites reinforced
with Ha crystals have been investigated for their suitability in bone repair
applications (Hillig
et al
., 2008). At a sufficiently high ratio of HA to gelatin,
compressive stiffness and resistance to swelling of these biomaterial suggested
their potential in replacing bone structures. However, this was achieved with
a degree of porosity not necessarily suitable for tissue engineering scaffolds
(see Section 14.5).
novel composites based on calcium phosphates/collagen doped with other
ions (e.g. Zn
+2
) have been synthesised (Santos
et al
., 2007). in this approach,
type i collagen was added to Ha and biphasic hydroxyapatite/b-tCP and the
mixture was blended until a homogenous composite was obtained. Doping of
the composite was obtained by adding 1.0 wt% Zn
2+
aqueous solution. The
cell substrate properties of the doped composite were compared to those of
the non-doped biomaterial. although both composites were shown to induce
osteoblast adhesion and later differentiation, no significant difference was
induced by the doped compound.
Collagen/Ha composites have also been produced in the form of
microparticles (Kim
et al
., 2007). Because of their physicochemical
properties, microparticles are considered among the most suitable candidates
for delivering drugs and cells in tissue engineering applications. it has been
suggested that microparticles may encourage the recruitment of osteoblasts
in
