The Improvement Of Biocompatibility Of Silk Fibroin Fiber Vascular Graft Materials By Layer-by-Layer Assembly

Vascular graft is the main treatment for cardiovascular disease.The use of autologous vascular vessels field is limited,because of the limited number and secondary damage.As a substitution,vascular graft has a huge application space.Large diameter vascular graft(inner diameter> 6 mm)has been well used in clinical field.And small diameter vascular graft(inner diameter ? 6 mm)hasn't achieved good transplant effect,because of the poor long-term flow rate.In this study,the regenerated silk fibroin/chitosan multilayers were deposited on the surface of silk fibroin fiber vascular graft material(SFF)via Layer-by-Layer assembly technique(Lb L).The aim of this study is improving the biocompatibility of SFF and provide ideas for small diameter vascular graft.The main contents of this thesis are as follows:(1)Constructing(RSF/CHI)n multilayers on the surface of SFF.Characterizing the hydrophobicity,multilayer morphology,thickness and roughness via doing WCA and AFM tests.(3)Testing the thermal stability and mechanical properties by doing TGA,tensile,bursting and suture strength tests.(4)Evaluating the biocompatibility of the SFF before and after the modification by doingin-vitro cell compatibility and blood compatibility experiments.The results and conclusions are as follows:(1)The thickness of the assembly film increased linearly and the surface contact angle changed alternately with the assembly process.The thickness of the(RSF/CHI)8 multilayers is 121 nm and the roughness is 56.9 nm.These results show that the(RSF/CHI)8 multilayers was existed.(2)The thermal stability and mechanical properties of the SFF after assmbled were not damaged.The wet strength of all samples was significantly lower than that of dry condition(p <0.01).All the SFF prepared in this study could meet the mechanical requirements of vascular grafts.(3)For(RSF/CHI)4~10,biocompatibility of SFF was significantly improved.The biocompatibility of(RSF/CHI)8 and(RSF/CHI)10 were not significantly different(p> 0.05).The cell proliferation rates of SFF assmbled(RSF/CHI)8 after 1 d,3 d and 5 d were 1.64,2.82 and 4.45 times that of SFF.The hemolysis rates of the unmodified SFF and the SFF assembled(RSF/CHI)8 were(0.72 ± 0.22)% and(0.24 ± 0.12)%,respectively.After(RSF/CHI)n multilayer assembled,the hemolysis rates decreased.The blood coagulation indexes(BCI)of SFF assembled(RSF/CHI)8 were 0.45 ± 0.03 and 0.34 ± 0.04,respectively.The results indicate that the anticoagulant properties of the assembled material has improved.In summary,there was no impact to the physical properties after modification on the SFF by Lb L technology.And the cytocompatibility and hemocompatibility were improved observably.However,the in vitro tests have some boundednesses.For this reason,the biocompatibility evaluation in vivo need to be explored in future study.