Biomedical Engineering Reference
In-Depth Information
(a)
(b)
5 µm
5 µm
FIGURE 7.30
Surface morphology of HAp coatings prepared by laser CVD after immersion in Hanks' solution for (a) 259.2 ks
and (b) 604.8 ks.
The degradation of bioceramic coatings prepared by PVD in SBF has been investigated.
ACP coating exhibited higher bioresorbability as compared with crystalline coating.
(73-75)
The elution from an ACP coating accelerated apatite formation in SBF,
(74)
which would
be advantageous in bone formation
in vivo
. In the immersion of thick calcium phosphate
coatings in Kokubo solution prepared by plasma spraying, the nucleation and growth of
bonelike apatite might be closely associated with the ACP phase suitably dissolving and
releasing calcium and phosphate ions.
(76)
On the contrary, apatite formation was observed
on the crystalline calcium phosphate coating but not on the ACP coating.
(73)
The surface
morphology and the mass of the eluted ions from the coatings might be also associated
with the apatite formation.
Biological Response
In vitro
and
in vivo
evaluations using cells and animals have been carried out for bioce-
ramic coatings prepared by PVD, focusing on the improvement of bone compatibility of
metallic biomaterials.
Alkaline phosphatase (ALP) activity can be an osteoblastic phenotypic marker and an
indicator of the first stage of osteoblastic differentiation.
(77)
Figure 7.31 shows ALP produc-
tion per DNA production of SaOS-2 cells on the coatings of ACP and OAp heat-treated
in a silica ampoule at 873 K for 7.2 ks prepared by RF magnetron sputtering on blasted
Ti-6Al-4V alloy substrates, compared with a noncoated blasted Ti-6Al-4V alloy sub-
strate and HAp disks.
(38)
The thickness of the coatings was 0.5 μm. The ALP activity of the
SaOS-2 cells on the calcium phosphate coatings on Ti substrates was significantly greater
than that on noncoated Ti substrates after culturing.
(33,38)
The calcium phosphate coating
enhances the osteogenic differentiation of osteoblasts on the surface of the Ti implant.
The interaction between calcium phosphate coatings and cells such as fibroblasts(78)
(78)
and
rat bone marrow cells
(79)
has been investigated, and the calcium phosphate coating would
improve the soft tissue compatibility due to the increase in cell spreading area and col-
lagen I formation.
(78)
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