Biomedical Engineering Reference
In-Depth Information
layer is deposited in vivo between the implant and bone (Kokubo et al.,
2003). Hong et al. (2008) developed a new bioactive glass ceramic (BGC)
nanoparticle and PLLA nanocomposite scaffold. The BGC nanoparticles
were synthesized using a combination of the sol-gel and coprecipitation
methods and were homogeneous nanospheres, 20-40 nm in diameter. The
compressive modulus of the scaffold increased from 5.5 to 8.0MPa, while
the compressive strength increased from 0.28 to 0.35MPa as the BGC
content was increased from 0 to 30 wt%. Moreover, PLLA/(20 wt%)-BGC
composites exhibited the best mineralization property in simulated body
fluid after 1 day of incubation, with apatite clusters covering almost the
entire surface of the scaffold.
16.5
Future trends
Current load-bearing implants with osteconductive surfaces or tissue
engineering based on natural or synthetic biodegradable scaffolds offer a
significant increase in the quality of bone repair and improved mechanical
properties. However, they still present limitations and hence there is
potential for major advances to be made in the field. Bone can actually heal
itself when it is broken or removed. However, this capability is impaired in
situations where substantial loss of bone has occurred due to a trauma or
tumour resection, leading to non- or delayed unions. This inability in bone
healing is also related to disease or old age (Graus, 2006).
Most of the current limitations in this field are related to the lack of
'smart' biomaterials with the capability to elicit specific responses at
molecular and cellular level. These biomaterials act as structural support
and delivery vehicles, providing cells and bioactive molecules necessary for
the formation of new bone tissue (Ma, 2004; Mistry et al., 2006). Ideal
biomaterial must possess mechanical properties adequate to support
growing bone tissue, good biocompatibility and high porosity
(Sitharaman et al., 2008). In addition, it should be able to avoid rejection
(e.g. associated with infections), react to changes in the immediate
environment and stimulate specific regenerative events at the molecular
level, directing cell proliferation, cell differentiation, and extracellular
matrix production and organization.
In the field of developmental biology, in-depth knowledge is increasingly
available on the key factors that regulate the highly complex processes of
bone growth, repair and regeneration. Unfortunately, the tremendous
potential of this source of information has not yet been fully exploited in
biomaterials science, since this field has developed from an engineering
tradition, yielding a biomechanically inspired rather than a bioinspired
approach towards tissue integration and regeneration.
Therefore,
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future research into bioceramic nanocomposites will be
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