Biomedical Engineering Reference
In-Depth Information
Figure 9.15
Current transient recorded during anodization [118].
Jowiz
et al
. [30, 32] investigated the biocompatibility
of the porous surface obtained after etching of Ti in 1M H
3
PO
4
+ 10% HF electrolyte (results of human osteoblasts culture see
chapter 12).
Mixture of H
3
PO
4
+ HF is a most often used electrolyte for
Ti surface modiication. Kim
et al
. etched Ti for 1 h in different
concentration of H
3
PO
4
+ HF and voltage conditions [44]. In the
osteoblast cells cultured for 1, 3, and 7 days (Fig. 9.16), they found
that samples a, b, and g show a good initial attachment of the cells
compared to the others, whereas proliferation levels for 7 days are
not good compared to the others. For example, samples a and g show
that the cell density for 1 day is almost the same as that for 7 days
[44]. Samples d-f show distinct proliferation levels for the period
of 7 days and in the case of sample e, a linear increase in the cell
density is observed through 7 days, and the highest cell density was
observed after culturing for 7 days [44].
The samples prepared in HF containing electrolytes allow
incorporation of F
−
ions in the oxide. Kim
et al
. suggest that the
initial attachment of cells is much stimulated on a titanium oxide
layer containing F
−
ions [44]. The enhanced proliferation levels of
cells in titanium oxides containing P O
4
3−
(especially with higher
concentration of H
3
PO
4
electrolytes) can be attributed to the
intrinsic properties of phosphate anionic groups that facilitate the
pre-adsorption of proteins to promote cell attachment/growth
on biomaterial surfaces [17, 20, 44, 119]. The morphological
changes during etching in H
3
PO
4
electrolytes (Fig. 9.17) are
attributed to the fast oxide dissolution by F
−
ions delayed via a