Biomedical Engineering Reference
In-Depth Information
500
µ
m
a
b
c
d
100
µ
m
g
e
VFP = 0.35
f
h
FIGURE 1.8
Typical structures of porous ceramics produced by different techniques: (a) porous hydroxya-
patite produced by the powder method combined with PVA as a porogen additive [205], (b) porous alumina by
freeze-drying method [170], (c) porous hydroxyapatite by gelcasting method [181], (d) bioactive glass foams by
sol-gel technique [188], (e) porous β-TCP by solid free-form technique [211], (f) β-TCP
+
hydroxyapatite foam
produced by the replication technique [207], (g) porous bioglass-based glass-ceramic foam by the replication
technique [80], and (h) porous structure of cancellous bone [215].
TABLE 1.12
Advantages of the Replication Technique over Other Methods
1. Cancellous bone-like macroporous structure
The porous structure produced by the replication technique is very similar to cancellous bone: highly porous network
with open and highly interconnected porosity, compared with the rest of the techniques (see Figures 1.8 (f, g, h)).
2. High commercialization potential
This technique is the simplest and most cost-effective method, and thus most suitable for commercialization, for
example, compared with SFF. SFF-RP, which are expensive processes, it may be a method for producing specifi c and
complex scaffold architectures.
3. Safety
It does not involve any toxic chemicals, compared with sol-gel and gelcasting techniques, which use HF to accelerate
polymerization.
4. Irregular or complex shape production ability
It can produce scaffolds of irregular or complex shapes, compared with standard dry powder processing or sol-gel-based
methods.
1.4.2 F
ABRICATION
OF
C
OMPOSITE
S
CAFFOLDS
The fabrication of polymer-ceramic composite scaffolds is based on conventional processes used
for neat polymeric scaffolds. Numerous techniques have been developed to process porous poly-
mer scaffolds for use in tissue engineering. Table 1.13 lists currently applied 3-D polymer scaf-
fold fabrication technologies, based on Ref. 1. Excellent reviews can be found in the literature
[1,216 -219].
While intensive efforts have been made to develop the processing technologies of polymer scaf-
folds, relatively less attention has been paid to the fabrication of porous composite scaffolds. Among
the technologies in Table 1.13, solvent casting with or without particle leaching [146,150,153,154]
and TIPS combined with freeze-drying [109-112,144,145] seem to be the most applied method to
the fabrication of polymer-ceramic composite scaffolds. In addition to these methods, there are
