Biomedical Engineering Reference
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It has been suggested (Park et al., 2003) that the carboxyl group of HA reacts not
only with amino groups of collagen but also with hydroxyl groups of collagen or HA
resulting in the formation of ester linkages. However, it is worth noticing that an es-
sential part of the scaffold is collagen therefore the most important reactions result in
the formation of the collagen network. The EDC is not incorporated into the amide
cross-links and it and other cytotoxic substitutes are completely rinsed out from the
matrix. The architecture of scaffolds should also provide appropriate porosity spatial
cellular organization. Spatial cellular organization determines cell-cell and cell-matrix
interactions, and is crucial to the normal tissue and organ function. Otherwise, poros-
ity and pore size of scaffolds play a vital role in tissue formation in vitro and in vivo
(Pietrucha, 2010b). Results of distribution and pore size in collagen-based scaffolds
prepared by mercury porosimetry are listed in Table 1.
table 1. Characterizations of the porous structure of the collagen-based scaffolds.
Nr
Collagen-based scaffold
Pore size [μm]
1-10
10-100 100-350
Pore volume [%]
1.
Collagen unmodified
6.8
71.9
20.0
2.
Collagen cross-linked by EDC
8.0
76.6
14.0
3.
Collagen modified by HA with EDC
22.2
65.5
11.0
The addition of HA influenced the density and the pore size of collagen-HA matrices.
That was verified by SEM (Figure 10).
Figure 10. (a) The SEM of unmodified collagen scaffold, (b) collagen cross-linked by EDC, and (c)
collagen with HA cross-linked by EDC.
It was observed that HA reduces the porosity of scaffolds with minimum about
68%. After cross-linking the pore size and porosity of the composite scaffold became
smaller and a 3D network structure with incorporated HA was formed.
Generally, the cross-linking by different agents leads to the formation of 3D net-
work structure with different pore size. This original approach might provide new
insights into the structural differences between natural tissue and novel class of 3D
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