Preparation And Characterization Of Crosslinked Elastin-Derived Polypeptide Hydrogels

In this paper, firstly, elastin-derived peptides(EP) with low molecular weight were prepared by acid degradation. Secondly, elastin-derived peptide hydrogels were fabricated by cross-linking EP with genipin, and the properties of elastin-derived peptide hydrogels were studied.Elastin-derived peptides with different molecular weights were prepared by acid degradation with different degradation time. This method was simple and the yield of elastin-derived peptides was higher compared with the gene engineering method. Elastin-derived peptides exhibited an inverse temperature transition and the inverse transition temperature(Tt) could be adjusted by changing the concentration and molecular weight of EP, pH and adding salt. Turbidity measurement showed that the Tt could be adjusted between 20 ? and 55 ? when the concentration of EP was 0.5 mg/m L-2.0 mg/mL. And Tt decreased along with the increase of peptide molecular weight, concentration and salt concentration. The effect of pH on Tt corresponded to the isoelectric point(PI) in solution: Tt had the minimum value at PI from which any deviating would cause Tt to rise.Then elastin-derived peptide hydrogels were fabricated with coacervation and by crosslinking with genipin which had good biocompatibility and low cytotoxicity. SEM tests showed that the freeze-dried EP hydrogels were obvious three-dimensional network structure and the pore size decreased significantly with the increase of the amount of genipin and the structure became stable. With the increase of the amount of crosslinking agent, the crosslinking degree increased gradually, and the overall density of freeze-dried hydrogel decreased first and then increased, but the porosity showed oppositely. The swelling ratio also increased first and then decreased, and the maximum swelling ratio occurred with the mass ratio of genipin was 1%. The swelling dynamic of hydrogels with different amounts of genipin showed the similar trend that all of them achieved a large swelling ratio in a short time, and then leveled off to reach swelling equilibrium. DSC tests and the swelling ratio changing with temperature showed that the crosslinked EP hydrogels were still thermo-sensitive and Tt increased slightly with the increase of the amount of genipin. And the deswelling dynamic showed that when the temperature was higher than Tt, the hydrogels would deswell quickly and deswelling ratio increased with the increase of the amount of genipin. The mechanical tests showed that the compression modulus of EP hydrogels was increased as the amount of genipin increased. The genipin-crosslinked EP hydrogel is a good biological material which has broad prospects in tissue engineering.