Biomedical Engineering Reference
In-Depth Information
(a)
(b)
Alginate
CPC
(c)
FIGURE 4.10
(
See color insert.
) Biphasic and mixed CPC-alginate scaffolds. (a) CAD models and realized
scaffolds in ( b) wet and (c) dry state are shown. The biphasic CPC-alginate scaffold (left) was
produced by alternate plotting of P-CPC and a high-concentrated alginate-PVA paste through
nozzles with an inner diameter of 610 µm (printing speed: 3 mm/s, dosing air pressure: 5.0
bar for the P-CPC and 7.4 bar for the alginate-PVA paste). For fabrication of the mixed CPC-
alginate scaffold (right), a CPC-alginate-PVA paste was plotted through a nozzle with inner
diameter of 610 µm (printing speed: 3 mm/s, dosing air pressure: 8.5 bar).
applied. To obtain a paste suitable for plotting of such scaffolds, CPC
powder
and alginate powder (in a mass ratio of 1 to 1) were mixed first, and then 1
g of the mixed CPC-alginate powder was added to 4.5 g of a 6% w/v PVA
solution, stirred until a homogeneous paste was achieved and filled in a car-
tridge of the printing head.
Both types of composite scaffolds, the biphasic CPC-alginate ones and the
mixed CPC-alginate scaffolds, were fabricated with a 0°0°/90°90° (XXYY)
lay-down pattern: two layers of the paste were deposited in the X direction
on top of each other and then in the Y direction the next two layers; this
sequence was repeated until the whole scaffold was finished. The appli-
cation of the XXYY lay-down pattern enhances the pore size in the x- and
y-direction and improves the interconnectivity of the pores compared to
the conventional XY lay-down pattern (i.e., alternating deposition of each
layer). After completion of the plotting process the biphasic CPC-alginate
scaffolds as well as the mixed CPC-alginate scaffolds were incubated in a 1
M CaCl
2
solution for cross-linking of the alginate and simultaneous setting
of the P-CPC for 5 h. Afterward, the CPC-alginate biphasic scaffolds were
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