Biomedical Engineering Reference
In-Depth Information
morphology are formed on the surface (Fig. 10.23c) with size of
the crystallites of about 200-300 nm (Fig. 10.23d). The apatite
morphology is typical to the one shown in Chapter 9. Ten days of
soaking results in more apatite forms on the surface compared
with that after soaking for 5 days. Furthermore, the apatite forms
a layer (Fig. 10.23e,f). The hydroxyl groups (OH
−
) remained on the
surface of the carbon microspheres after the process are important
for the apatite formation in SBF, which provides favorable sites for
calcium phosphate nucleation [31]. The potential mechanism of
apatite formation on the surface was proposed by Wu and Chang
(Fig. 10.24) [62]. Surface of the carbon microspheres is negative
due to OH
−
groups, which provide favorable sites for calcium
phosphate nucleation. The Ca
2+
, PO
4
3−
, and CO
3
2−
ions are assem-
bled on the surface of carbon microspheres to form amorphous
carbonate apatite. With the increase of soaking time, the amorphous
carbonate apatite grown into crystalline carbonate apatite.
Figure 10.24
Schematic mechanism for the apatite formation on the
surface of carbon microspheres in SBF [62].
