Surface Modification And Properties Study Of Pet Fabric For Vascular Graft

PET, with good mechanical behavior and chemical stability, has been widely used for biomedical material, especially for the material of blood vessel prosthesis. PET blood vessel prosthesis with large or medium diameter have been applied in clinic therapy and created considerable economic interests and social benefits. However, because of the problem of thrombopoiesis and endothelialisation badly in short-term, the application for PET blood vessel prosthesis with small diameter has not been ideal. As the result, the modification for PET biomedical material of blood vessel prosthesis has been one of hotspots in the research area for years. In this research, the methods of plasma treatment and ultraviolet irradiation were adopted in the modification of PET material for artificial blood vessels to introduce amino groups, and then, molecules of silk fibroin and heparin were adhered or grafted onto the surface of materials. The purpose is to gain the PET material for blood vessel prosthesis with excellent mechanical and biological property, which could realize the function of anti-thrombopoiesis and promoting the regeneration of vascular endothelial cells in early stage of blood vessel prosthesis grafting.In the paper, monomers of acrylamide were firstly grafted onto the PET vascular graft through two preprocessing methods, including normal temperature and pressure plasma treatment and ultraviolet irradiation, and analyzed the two methods'factors. Secondly, with the method of Hoffman degradation-bonding of positive and negative ions-cross linking of glutaraldehyde, the PET vascular graft, modified by the solution of regenerated silk fibroin and heparin with different concentration, was prepared and tested. Thirdly, the blood and PET vascular graft modified by regenerated silk fibroin and heparin were evaluated by biological tests in vitro such as thrombus formation test, hemolysis test and relative release of heparin test, to distinguish the biomedical expression of modified PET materials. At last, the cell compatibilities of PET vascular graft modified by regenerated silk fibroin and heparin were evaluated by culturing cells endothelial on their surface.As a result, firstly, the acrylamide polymer was successfully grafted onto the surface of PET vascular graft by the means of Plasma and Ultraviolet irradiation treatment through FTIR spectroscopy. As showed from the result of bursting strength test, plasma leads to more loss in graft strength than ultraviolet irradiation. As seen from the result of single factor experiment, the best grafting ratio and hydrophilicity could be obtained uner the conditions:Ultraviolet irradiation power of 5800μW/cm2, benzophenone concentration of 0.2M/L, treated time of 20 min, acrylamide concentration of 2M/L.Secondly, the PET vascular graft modified by acrylamide polymer could availably combine with regenerated silk fibroin and heparin after series reactions like Hoffman degradation and glutaraldehyde cross-linking. The result of FTIR showed that the characteristic peaks of regenerated silk fibroin and heparin were expressed on the surface of PET. From picture of SEM, we could found regenerated silk fibroin formed the shape of "bamboo joint" and distributed uniformly. The weight loss rate of silk fibroin and heparin attaching on the PET surface is less than 19% after high intensity ultrasonic cleaning in water for 60min. However, as shown from the result of bursting test, the strength of PET vascular graft decreased after degradation and cross-linking reactions.Thirdly, the tests of thrombus and hemolysis in vitro demonstrated that the PET vascular graft modified by heparin could inhibit thrombus formation and maintain integrity for the structure and function of red blood cells to a grade extend; the regenerated silk fibroin could also reduce the formation of thrombus and toxicity to blood red cells. Heparin grafted or adhered to the PET surface released gradually in PBS buffer solution, and anticoagulation property of modified graft also decayed accordingly, but the hemolysis test for graft emerged in the PBS for 48 hours showed that the hemolysis rate for blood red cells was less than 5%, still meeting the criterion of biomedical materials.Furthermore, porcine iliac artery endothelial cells (PIEC) were seed on the surface of graft to analyze the cell proliferation. MTT test demonstrated that PET modified by regenerated silk fibroin had excellent cell-compatibility, and the increase of silk fibroin was good for proliferation of endothelial cells. The picture of SEM showed that endothelial cells, with normal size and shape, could adhere to the modified PET graft, and grow well.In sum, acrylamide polymers have been successfully grafted onto the surface of PET vascular graft through plasma and ultraviolet irradiation treatments; regenerated silk fibroin and heparin could availably combine with PET graft using acrylamide as a spacer; the PET vascular graft modified by regenerated silk fibroin and heparin, with excellent mechanical performance, had good blood and cell compatibility in vitro. The research could provide some experimental basis and theoretical supports on the development of small diameter PET vascular graft which shows excellent anti-thrombopoiesis property.