Biomedical Engineering Reference
In-Depth Information
optimize the properties of the implant scaffold to lead to enhanced bone fill at the defect site.
A previous study with an alginate/HA composite had shown that scaffolds of this type have a
porous structure that supports osteoblastic cell attachment and growth
[60]
. It appears the addition
of alginate to nCS optimizes the conditions to enable more osteoblastic cell growth and thus more
bone fill in the rat calvarial model, however, more studies are needed to understand the nature of
alginate's effects in this system.
In order to better understand the nature of the scaffold created by combining nCS and alginate
the microscopic structure and cell-material interaction of different proportions of nCS and alginate
were studied in our laboratory. Samples of different proportions of alginate (5%, 10%, 15%, 20%,
and 50% by weight) and nCS were incubated in water for 24 h. It was noted that once the scaffolds
were placed in water, they started to absorb water and swell, with the loss of divalent cations in the
surrounding liquid causing dissolution of the ionically cross-linked alginate. The integrity of the
50%, 20%, and 15% alginate scaffolds was lost completely after 24 h. Although the 10% and 5%
alginate scaffolds still kept their shape, their mechanical properties were weakened (
Figure 19.7
).
Scanning electron microscope (SEM) analysis showed increased roughness on the surface which
may be due to the sponge-like consistency of the scaffold (
Figure 19.8
). The alginate absorbed
water and became gelatinous with the gel layer isolating nanoparticles of CS and covering the
FIGURE 19.7
Dissolution behavior of nCS and alginate composite scaffolds after 24 h incubation in water. From left to right:
nCS:alginate
50:50, 80:20, 85:15, 90:10, and 95:5.
5
(A)
(B)
(C)
200
µ
m 150X
200
µ
m 150X
200
µ
m 150X
FIGURE 19.8
(A)
(C) SEM images of nCS and alginate samples after 24 h of incubation in water at 150
magnification.
3
(A) nCS:alginate
5
95:5, (B) nCS:alginate
5
90:10, and (C) nCS:alginate
5
50:50.
