Biomedical Engineering Reference
In-Depth Information
fabricate bone-resembling microstructures. Further details on
calcium
orthophosphate/collagen
composites
might
be
found
elsewhere [36, 725].
6.4.5
Biocomposites with Other Bioorganic Compounds
and/or Biological Macromolecules
The biggest practical problems with collagen type I are its cost and the
poor definition of commercial sources of this material, which makes
it difficult to follow up on well-controlled processing. Therefore,
collagen type I can be replaced by other compounds. One should
notice that, besides collagen, both human and mammalian bodies
contain dozens types of various bioorganic compounds, proteins,
and biological macromolecules. The substantial amount of them
potentially might be used to prepare biocomposites with calcium
orthophosphates. For example, a biologically strong adhesion (to
prevent invasion of bacteria) between teeth and the surrounding
epithelial tissues is attributed to a cell-adhesive protein, laminin
[789]. In order to mimic the nature, a laminin/apatite biocomposite
layer was successfully created on the surface of both titanium
[790] and EVOH [791, 792] using the biomimetic approach. A more
complicated laminin/DNA/apatite biocomposite layer was found to
be an efficient gene transfer system [793].
Calcium orthophosphate/gelatin biocomposites are widely
investigated as potential bone replacement biomaterials [317, 336-
338, 444-452, 466-474, 487, 521-523, 554, 619-624, 794-807]. For
example, gelatin foams were successfully mechanically reinforced by
HA and then cross-linked by a carbodiimide derivative [317]. Such
foams were shown to be a good carrier for antibiotic tetracycline
[798]. Several biocomposites of calcium orthophosphates with
alginates have been prepared [471, 617, 618, 622, 709, 808, 809]. For
example, porous HA/alginate composites based on hydrogels were
prepared both biomimetically [709] and by using a freeze-drying
technique [808]. Another research group succeeded in preparation
of biphasic but monolithic scaffolds using a similar preparation
route [810]. Their biocompatibility in cell culture experiments and
in vitro
biodegradability were high; however, a mechanical strength
could be better.
Various biocomposites of calcium orthophosphates with chitosan
[298, 482, 500, 512, 527, 565, 645-653, 674, 675, 690, 695, 799, 807,
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