Silk Fibroin Modified Phbhhx Cardiovascular Scaffolds For Tissue Engineering Research

Biocompatibility is one of the important issues required for developing tissue-engineering materials.Although the poly(3-hydroxybutyrate-co-3- hydroxyl hexanoate)(PHBHHx)has been attractive for its controllable mechanical properties recent years,its cell affinity is still necessary to be improved for the requirements.For this purpose,the regenerated silk fibroin(SF) was coated on the PHBHHx films and its porous scaffolds.In order to verify the modifying results,endothelial-like cell line of ECV304 cells and human umbilical vascular endothelial cells(HUVECs) were seeded into the scaffold.The following results were obtained:1.Water contact angle and surface free energy demonstratted that SF was successfully anchored on the surface of PHBHHx and enhanced the surface hydrophilicity which is generally thought to be easier for the attachment and proliferation of cells..2.The mechanical test showed that SF-modified PHBHHx(SF/PHBHHx) film has a maximum tensile strength of 11.5±0.5 MPa and elongation at break of 175±5%. The little difference between them demonstrated that there is no change in mechanical properties during the modifying process.3.ATR-FTIR spectroscopy demonstrated that SF firmly attached on the scaffold by the hydrogen bonding interaction between SF and PHBHHx even flushed for 21 days in the phosphate-buffer saline(PBS) solution(pH = 7.4).4.The histochemical analyses of cells stained by the hematoxylin and eosin(HE) as well as cell nuclei stained by the 4',6-diamindine-2'-phenylindole(DAPI) demonstrated that cell attached and reached nearly 100%confluence on the SF/PHBHHx films when cultured for 4 days,which was much faster than that on the pure PHBHHx film.5.SEM observation illuminated that both ECV304 and HUVECs grew better in the SF/PHBHHx than in the PHBHHx scaffold when seeded for 5 and 7 day, respectively.6.Moreover,the assay of cell activity by the 3-(4,5-dimethyl thiazol -2-yl)-2, 5-diphenyl terazolium bromide(MTT) showed quantitatively that the number of cells on the SF/PHBHHx porous scaffolds was significant more than that on the unmodified ones after 4,8 and 14 days' culture for ECV304 cells and 3,5 7days' culture for HUVECs,respectively.7.The higher collagen content on the modified scaffolds demonstrated that more extracellular matrices(ECM) were secreted by HUVECs.