Biomedical Engineering Reference
In-Depth Information
analogues of nanodimensional building blocks of biominerals should
be highlighted in the entire subject of biomineralization.
In the case of nanodimensional DCPA, decreasing of DCPA
particle dimensions were found to increase the Ca- and PO
-ions
releases from DCPA-based biocomposites. Therefore, biocomposites
based on nano-sized DCPA, possessing both a high strength and good
release of Ca- and PO
4
-ions, may provide the needed and unique
combination of stress-bearing and caries-inhibiting capabilities
suitable for dental applications [466].
4
3.7.4
Other Applications
Several other applications of nanodimensional and nanostructured
calcium orthophosphates are in progress, some of which are
described here.
Surface modification of nanodimensional calcium
orthophosphates was performed in order to modulate their
colloid stability, prevent dissolution in the case of low pH, avoid
inflammation, serve as an intermediate layer to allow strong bond
formation between HA/polymer matrices and potentially enhance
its bioactivity or improves its conjugation ability with special
functional groups [12, 600-603]. Such surface modified nano-sized
particles might be applied for oral insulin delivery [604]
In another aspect, many strategies have been employed to load
various agents, i.e. therapeutic, bio-imaging, etc., to nanodimensional
calcium orthophosphates (mainly, apatites). In summary, these
strategies can be broadly categorized into two main approaches. One
approach is to load these agents during the synthesis — so-called
in situ
loading. This is done by adding the desired agent(s) to the
reaction mixture before the formation of a nanodimensional calcium
orthophosphate is completed. The second approach is to load the
agent(s) only after a nanodimensional calcium orthophosphate
has been fully synthesized or, in other words, after the synthesis
process — so-called
loading. This is mainly done through
surface adsorption where the agents are adsorbed onto the surfaces
of pre-synthesized nanodimensional particles [605]. Therefore, due
to established biocompatibility, ease of handling, and notorious
adsorption affinity, nano-sized calcium orthophosphates have been
applied as non-viral carriers for drug delivery and gene therapy
[173, 256, 282, 289, 435, 463, 478, 606-615]. After loading with
ex situ
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