Biomedical Engineering Reference
In-Depth Information
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Figure 4.1
Systems for cardiac growth factor delivery: hydrogels, microparticles and
nanoparticles, scaffolds and liposomes.
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They can be classified as physical or chemical gels depending on the process
by which the cross-links within the networks are produced. The synthesis
method determines their properties. Physical hydrogels are less toxic which
would be desired for biomedical use, however chemical gels have better
mechanical properties but the agents involved in their synthesis could
damage the molecules (e.g., drugs, proteins) added in the solvent.
39
GFs can be directly loaded into hydrogels showing a rapid burst release
during the initial swelling phase, followed by the extended release of protein
retained in the gel. It has been proved that the release profile can depend on
the GF, since the interaction with the same biomaterial is different for each
factor and the cross-linking density of the polymer networks can be changed
in order to ensure the presence of the GF the needed time.
40
A synthetic
hydrogel-DDS needs to be modified in order to induce release of the GF
according to the cellular demands at the target site. This can be achieved by
including strategies such as specific substrate-enzyme coating or inducing
physical responsiveness in the target tissue.
41,42
A large variety of hydrogels, both synthetic and natural were first directly
loaded with GFs. Collagen type I hydrogel with the heparin-binding GFs was
built to test their release profile in vitro;
43
FGF-2 was incorporated in a
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