Biomedical Engineering Reference
In-Depth Information
The main species of water radiolysis reacting with the mentioned polymers are OH
radicals. They attack the macromolecules and abstract hydrogen atoms. The structure
of resulting macro radicals depends on the type of polymers. Mutual recombination
of macroradicals induces intra- and inter-molecular cross-links. Then semi- and inter-
penetrating INP 3D sterile polymer network without any additional chemical cross-
linking agents are formed. Cross-linking was also found to improve the mechanical
and morphological properties of the hydrogels. Small amounts of collagen and MPEG
in structure of PVA lead to an unexpected improvement of porosity and strong me-
chanical integrity of PVA-collagen-MPEG hydrogel. Beneficial effects of PEG on the
stability of pores of PVA have been also observed by others (Bodugoz-Senturk et al.,
2008). From the viewpoint of biomedical application it seems that addition of collagen
and MPEG to PVA would produce a highly elastic and strong scaffold that would fa-
cilitate high levels of cell attachment and growth. PVA-MPEG-Collagen hydrogels are
promising materials to use as scaffolds in tissue engineering as well as a biomaterial
for osteochondral defect repair or as artificial cartilage.
Work on many composite systems of collagen sponge-shape matrix with GAG
has been reported in research papers, published in the last 10 years. Among them the
author of this publication explored preparation of new composite of collagen with HA
and CS to develop innovative biological scaffolds for tissue engineering (Pietrucha,
2005, 2007, 2010). In these studies, particular attention has been paid to the prepara-
tion and characterization of cross-linked collagen-HA/CS matrices with potential for
use in tissue engineering. To prepare collagen modified by HA/CS two complementary
cross-linking methods, dehydrothermal (DHT) pre-treated and 1-ethyl-3-(3-dimethyl
aminopropyl) carbodiimide (EDC) have been introduced.
Modifications in molecular organization of collagen-HA/CS scaffold induce varia-
tions in the material application properties, and more particularly of their thermal,
mechanical, and dielectrical properties. The typical differential scanning calorimetry
(DSC) and termogravimetric analysis (TGA) of collagen and collagen cross-linked by
mixture EDC and NHS in the presence of HA are shown in Figure 7. The thermograms
obtained by DSC for both collagen modified with HA and collagen alone evidenced
Figure 7. DSC ( ) and TGA ( ) thermograms of collagen unmodified (A) and (B) modified by HA.
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