Biomedical Engineering Reference
In-Depth Information
Fig. 6 Alginate-sulfate (a) and the model of reversible binding (b) (reprinted by permission
from [
203
])
The self-assembling peptide nanofibers presenting heparin were capable of binding
paracrine factors from a medium phase, primarily heparin-binding factors. When
these factor-loaded materials were injected into the heart following coronary artery
ligation in a mouse ischaemia-reperfusion model of acute myocardial infarction,
significant preservation of hemodynamic function was observed [
173
].
Alginate-Sulfate Biomaterial
To mimic the natural interactions of heparin-binding proteins with heparin/heparan
sulfate and obtain prolonged release of growth factors, our group has developed an
innovative alginate biomaterial with affinity-binding sites for heparin-binding
proteins, by sulfation of the uronic acid monomers in alginate (Fig.
6
)[
77
].
Surface plasmon resonance (SPR) analysis revealed strong binding of various
heparin-binding proteins to alginate-sulfate, but not to alginate [
76
,
77
]. The
equilibrium binding constants to alginate-sulfate were comparable to those
obtained between the peptides and heparin. We found the release rate from bio-
conjugates of alginate-sulfate/growth factors to be dependent on the growth factor
binding constants (K
A
) and the initial concentrations of individual components
forming the bioconjugate (Table
1
). Additionally, the interactions of these mole-
cules with alginate-sulfate were found to enhance their stability against enzymatic
proteolysis induced by trypsin [
82
,
83
]. This is of great importance if the delivered
proteins are to remain active for prolonged periods of time in harsh environments,
where extensive protein degradation takes place.
Injectable and implantable scaffolds composed of combinations of alginate-
sulfate with unmodified alginate provided a unique type of a novel affinity-binding
system, which has been capable of the sequential delivery of multiple signaling
molecules, while retaining the already mentioned properties and characteristics of
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