Biomedical Engineering Reference
In-Depth Information
the surfaces of the microspheres were coated with unmodifi ed and bio-
active HAp nanoparticles, and water-soluble drugs can be loaded in the
water domains.
9.4
Evaluation of Cell Adhesion Properties of
HAp-Biodegradable Polymer Nanocomposite
Microspheres
Thanks to excellent cell adhesion properties of HAp [7], the HAp-coated
biodegradable polymer microspheres are expected to show improved
cell adhesion properties. The cell adhesion properties of PLLA core/HAp
shell nanocomposite microspheres were evaluated using L929 mouse fi b-
roblast cells as the model system. As shown in Figure 9.10, it was observed
that the cells adhered with stretching their lamellipodia on the surface of
the nanocomposite microspheres. When bare PLLA microspheres, where
HAp nanoparticles were removed by dissolution from the nanocomposite
microspheres, were used in a control experiment, the cells did not stretch
lamellipodia, but adhered to the microspheres with small contact area in a
nearly spherical shape.
The number of the cells adhered on the HAp nano-
particle-coated microspheres was 763 cells/mm
2
, which is statistically lar-
ger than that on the bare PLLA microspheres (574 cells/mm
2
) as shown
in Figure 9.11. Results obtained by counting the cells detached from the
(
a
)
(
b
)
(
c
)
Cell
HAp-coated PLLA
2 μm
1 μm
20 μm
(
d
)
(
e
)
(
f
)
Cell
Bare PLLA
20 μm
2 μm
1 μm
Figure 9.10
SEM images of L929 fi broblast cells adhered on the HAp
nanoparticle-coated PLLA microspheres (a-c) and the bare PLLA microspheres
(d-f) after incubation at 37
C for 24 h. (b,c) and (e,f) are magnifi ed images of
(a) and (d), respectively. Reprinted with permission from [52]. Copyright © 2009
American Chemical Society.
°
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