Titanium Phosphate Glass Microspheres as Microcarriers for In Vitro Bone Cell Tissue Engineering - Biointerfaces: Where Material Meets Biology - page 116

Metal oxides are known to exert their own influence on glass degradation
based on several factors such as metal ion valency and atomic radius. 65
When metal oxides with Z3 þ valencies are incorporated in the glass
structure, the overall trend is for the phosphate ion release to mirror the
degradation profile so that glasses that degrade at slower rates release
smaller amounts of all phosphate species. However, glasses containing di-
valent metal oxides may not show this trend; for instance, P 2 O 5 -CaO-Na 2 O-
ZnO glasses with different ZnO contents release phosphate ions at roughly
similar rates, whereas in P 2 O 5 -CaO-Na 2 O-SrO glasses, there is no particular
consistency in terms of the overall trend of phosphate release. 20,35
Most studies on titanium phosphate glass degradation have been carried
out using macroscopic glass discs. The experimental technique used is a
commonly used weight loss model. 66 However, for investigating the deg-
radation of glass microspheres, we have used a novel time lapse imaging
technique. This technique takes advantage of the microscopic size of these
spheres to provide visual evidence of microsphere degradation while sim-
ultaneously providing quantitative data to correlate the microsphere deg-
radation with the glass composition.

d n 3 r 4 n g | 3

5.3.1 Materials
The following refers to microspheres made from a glass of known density.

5.3.2 Equipment
Analytical balance (resolution of 0.1 mg)
Alcohol wipes (Azowipe bactericidal wipes may be used)
Beaker
Brush
Camera (TCA-10.0-N; Tucsen Image Technology Inc., China)

.

TIP: A wide range of cameras equipped with software to capture time-
lapse images are available and can be used for this experiment.

Desktop PC loaded with mManager microscopy open source software
(version 1.4; Ron Vale Lab, University of California - San Francisco,
USA) and ImageJ (version 1.47; National Institutes of Health, USA)
Micro spatula
Microscope incubator system (Solent Scientific, UK)

TIP: The incubator system is used in order to carry out the time-lapse
experiment at 37 1C. If such an incubator system is not available, the same
experiment can be carried out at room temperature; our previous experi-
ence shows that the lower temperature will not drastically affect the ex-
perimental results.