Biomedical Engineering Reference
In-Depth Information
(A)
(B)
P
< 0.001
P
< 0.001
200
250
***
***
150
200
150
100
50
0
100
50
0
FIGURE 15.8
Cell viability and cell proliferation. The MTT assay and cell proliferation BrdU assay were used to evaluate the
behavior of cementoblasts in direct contact with particles. A significant increase in cell viability and cell
proliferation in the presence of bioactive glass nanoparticles was observed when compared with the control group.
Bioactive glasses, especially when processed as porous scaffolds, have inferior mechanical
properties. In particular, the low toughness values limit their use in situations where there is a load
application. Different concepts for the structural design of composites have been proposed to over-
come the inherent fragility of bioactive glasses, and advances in nanotechnology have stimulated
the creation of composite biomaterials with improved properties and functions.
One approach to improve the mechanical properties of the bioactive glass is the production of
organic/inorganic hybrid in which an inorganic phase, with nanometric dimensions, is inserted into
a polymeric matrix. The sol-gel process is potentially useful in enabling the combination of poly-
mers with ceramic materials at the nanometer scale. It allows for the preparation of ceramic materi-
als at temperatures compatible with the polymer processing. Bioactive glass composites have been
developed based on this strategy
[8,16,19,80
85]
.
The use of bioactive glass nanoparticles in a polymer matrix mimics the structure of natural
bone, which contains nano-scaled-size HA cristallites. Webster et al. (2001) reported a significant
increase in protein adsorption and osteoblast adhesion on ceramic nanocomposites in comparison
with ceramic microcomposites
[76]
.
Several synthetic or natural polymers, such as polyvinyl alcohol (PVA), chitosan, polyethylene
glycol (PEG), gelatin, collagen, poly(caprolactone) (PCL), and polyurethanes, are used to construct
nanocomposites for tissue engineering applications. Biopolymers have the advantage of being bio-
degradable and present similar structure to the extracellular matrix components. The polymer phase
plays a fundamental role in the final properties of the composite.
Misra et al. (2008) reported the successful preparation of poly(3hydroxybutyrate) (P(3HB))/
bioactive glass nanoparticle composite. The addition of nanoparticles has shown a significant
effect on the mechanical properties of the material. Moreover, they demonstrated in vitro
degradation (30 days) in simulated body fluid and an increase in bioactivity
[86]
.
