Biomedical Engineering Reference
In-Depth Information
Akashi and co-workers developed a procedure to prepare
calcium orthophosphate-based biocomposites by soaking hydrogels
in supersaturated by Ca
ions solutions in order to
precipitate CDHA in the hydrogels (up to 70% by weight of CDHA
could be added to these biocomposites) [848]. This procedure was
applied to chitosan; the 3D shape of the resulting biocomposite
was controlled by the shape of the starting chitosan hydrogel
[849]. Another research group developed biocomposites based on
in situ
2+
and PO
4
3−
calcium orthophosphate mineralization of self-assembled
supramolecular hydrogels [850]. Other experimental approaches
are also possible [851].
Various biocomposites of CDHA with glutamic and aspartic amino
acids, as well as poly-glutamic and poly-aspartic amino acids, have
been prepared and investigated by Bigi et al. [346, 347, 852-855].
These (poly)amino acids were quantitatively incorporated into CDHA
crystals, provoking a reduction of the coherent length of the crystalline
domains and decreasing the crystal sizes. The relative amounts of
the (poly)amino acid content in the solid phase, determined through
HPLC analysis, increased with their concentration in solution up to a
maximum of about 7.8 wt.% for CDHA/aspartic acid and 4.3 wt.% for
CDHA/glutamic acid biocomposites. The small crystal dimensions,
which implied a great surface area, and the presence of (poly)amino
acids were suggested to be relevant for possible application of these
biocomposites for hard tissues replacement [346, 347, 852-855].
A schematic description of a biocomposite formation from amino
acids and ACP is shown in Fig. 6.4 [856].
Figure 6.4
A proposed mechanism for the formation of ACP/amino acid
biocomposites in aqueous solutions. Reprinted from Ref. [856]
with permission.
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