Biomedical Engineering Reference
In-Depth Information
(a)
(b)
500 µm
500 µm
FIGURE 4.5
Scanning electron microscopy (SEM) images of plotted CPC scaffolds (a) with and (b) without
application of PVA paste as supporting material (side view).
would harden immediately after extrusion and thereby achieve an increased
stiffness that should be sufficient to support the weight of the whole scaffold
resulting in uniform and open pores in the x-/y-direction. However, prob-
lems concerning the weak bonding between several layers and potential
blocking of the nozzle are still unresolved.
4.2.2 Characterization of the Plotted CPC Scaffolds
CAD/CAM enables the fabrication of CPC scaffolds with different size and
shape by using the 3D plotting technique, not only with respect to the overall
shape that fits into a patient-specific defect but also with an optimized inner
pore size and structure to support cell attachment and migration as well as
blood capillary ingrowth on the one hand and to mediate adequate mechani-
cal stability on the other hand. As shown in Figure 4.2f, CPC scaffolds with
designed pore size and morphologies can be fabricated by using the 3D plot-
ting technology illustrating the key advantage of RP techniques—compared
to conventional methods used for scaffold preparation—namely, the control
and optimal adjustment of pore parameters such as size, interconnectivity,
distribution, and morphology. The strong influence of size and morphology
of the pores on scaffold performance concerning mechanical properties, cel-
lular response, and new bone formation in vivo has been demonstrated in
many publications. Some studies have revealed that scaffolds with pore size
around 300 to 400 µm were optimal for bone tissue engineering (Tsuruga et
al. 1997; Murphy et al. 2010). In addition, a complete interconnectivity of the
pores is also necessary for cell growth and migration, and homogeneous
new bone formation in the scaffold.
One important issue with respect to tissue engineering applications is
the resolution of plotted scaffolds, as it has a strong influence on pore size
and structure. The resolution depends mainly on characteristics of the basal
 
Search WWH ::




Custom Search