Study On The Chemical Modification On Elastin-derived Peptides And The Properties Of Its Thermo-sensitive Hydrogel

Elastin had a broad applied value due to its good mechanical properties andbiocompatibility. Unfortunately, as an intended source of biomaterials, its persistenceand high insolubility largely precluded elastin from manipulation. Elastin-derivedpeptides had attracted the attention of researches because it remained the excellentproperties of elastin and it had coacervation characteristics. However, there was littleresearch tried to make a further study about it. So in this paper, firstly, elastin-drivedpeptides with low molecular weight were prepared by acid degradation. Secondly,elastin-drived peptides were modified by chemical crosslinking method, and theproperties of modified elastin-drived peptide thermo-sensitive hydrogel were studied.Elastin-drived peptides were modified by glutaraldehyde (GA), and the effect ofdifferent factors on the thermo-sensitivity of those systems was studied. It revealedthat the crosslinking of elastin-drived peptide with GA involved the reaction ofprimary amine with the aldehyde groups of GA to generate secondary amine. GAmodified elastin-drived peptide was a thermo-sensitive system. The inverse transitiontemperature (Tt) decreased along with the increasing of the amount of GA, proteinconcentration and salt concentration. With the increasing of pH, Ttdecreased firstlyand then increased, Ttreached minimum when pH was about5.0. And the propertiesof freeze-dried GA modified elastin-drived peptide hydrogels were studied. SEM testsshowed that the pore size decreased significantly with the increasing of the amount ofGA, and the structure became stable along with increasing of protein concentration.With the amount of crosslinking agent increased, the density decreased firstly andthen increased, while the porosity and water swelling performanced the opposite trend.And the water swelling dynamic of hydrogels with different amouts of GA alsoshowed the similar trend. At the same time, the swelling ratio of freeze-driedhydrogels decreased as the temperature rose, while it showed an unapparent trend.And with the increasing of pH the swelling ratio of the freeze-dried hydrogelsdecreased firstly and then increased, the swelling ratio of the freeze-dried hydrogelsreached the minimum when pH was about5.0. It gradually decreased as the saltconcentration rose.Secondly, elastin-drived peptides were modified by genipin (GP). With the increasing amount of GP, the degree of crosslinking showed an overall upward trend,and the degree of crosslinking stabilized when the amount of GP was up to20%. TheSEM showed that the modified sample had apparent three-dimensional networkstructure. Turbidity analysis showed that Ttdecreased along with the amount of GPincreasing. GA modified elastin-drived peptide materials showed a betterthermosensitivity than GP modified elastin-drived peptide materials by comparingtheir contrasted turbidity.