Titanium Phosphate Glass Microspheres as Microcarriers for In Vitro Bone Cell Tissue Engineering - Biointerfaces: Where Material Meets Biology - page 120

5.3.4 Expected Outcomes and Other Considerations
The above procedure will yield a series of images which will provide visual
evidence of microsphere degradation over the time period of the experiment.
These images can be converted into time-lapse videos using software such as
Microsoft Windows Movie Maker or QuickTime 7 Pro. Furthermore, quan-
titative data on sphere diameter reduction with time can be obtained which
allows the correlation of microsphere degradation rates with the glass
composition. It is worth noting that the procedure may not work for
microspheres made of highly degradable glasses. To elaborate, consider the
microspheres of the titanium-free phosphate glass (Ti0 in Figure 5.4). By
t ¼ 24 h, a hydrated layer begins to form on the outer surface of most of the
microspheres and the microspheres continue to degrade inside this struc-
ture. As it degrades within the layer, each microsphere becomes increasingly
irregular in shape and constantly changes its position inside the structure.
In some cases, the hydrated layers of adjacent microspheres come in contact
and fuse together, with the microspheres continuing to degrade inside the
newly formed larger layer. By t ¼ 72 h, almost all the microspheres have
degraded completely, leaving behind only the transparent structures. Under

d n 3 r 4 n g | 3

.

Figure 5.4 Time-lapse acquisition images showing the degradation of microspheres
of glasses containing 0, 1, 3 and 5 mol% TiO 2 at 0, 24, 48 and 72 h for
each composition.