Research On High Elastic And Low Swellable Hydrogel Vascular Graft Materials

Vascular graft is a kind of prosthesis for repairing and replacing diseased vessels, large diameter artificial blood vessels products has been successfully used in clinic, and small diameter artificial blood vessels was still in the stage of research. Hydrogels have been used in bio-materials field for many years, but less research as artificial blood vessel materials. On the one hand, the mechanical properties of hydrogel need to be improved to meet the performance requirements of artificial blood vessels. On the other hand, the hydrogel swells in volume under wet environment and will lead to reduced diameter and then cause thrombosis.In this study, sodium alginate and acrylamide were as raw materials, phsical crosslinking and chemical crosslinking were combined, prepared a series of hydrogels. I analyzed the effects of sodium alginate and Ca Cl2 mass fraction on swelling ratio and mechnical properties. In the priority to reduce the swelling ratio, and then improve the mechanical properties, select sodium alginate mass fraction of 2.3%, CaCl2 mass fraction of 0.42% as optimizing materials. Then, I designed the pipe organ casting mould, explored the preparation of polyester monofilament braided tube, respectively to obtain the sodium alginate- polyacrylamide hydrogel pipe and enhanced pipes, and carried on the the performance characterization. Finally, getting on the resulting high elastic and low swellable of alginate- polyacrylamide hydrogel vascular graft materials biocompatibility evaluation, including cell activity and hemolysis rate.According to alginate-polyacrylamide hydrogel preparation program, nine samples of different parameters looked as a pale yellow transparent gel-like, no significant differences in appearance; they were soft, good elasticity, toughness. SEM results showed that:alginate-polyacrylamide hydrogel cross-section is the porous structure, more uniform pore size, pore size mainly distributed in 40 ~ 60μm; the results of swelling ratio showed that:nine samples reached swelling equilibrium within 12 h. In priority to reduce the swelling ratio, I selectpreparation parameters as sodium alginate mass fraction of 2.3%, CaCl2 mass fraction of0.42%. That is 5# hydrogel sample as the study later.By designing mould, casting alginate hydrogel solution is prepared alginate-polyacrylamide hydrogel vascular graft materials. The study found that the braiding angle of 55 ± 0.5 ° of polyester monofilament braided tube, its diameter reduction ratio of 17.60 ± 0.82%, and it is closed with 5# hydrogel pipe. The swelling ratio of 5# hydrogel vascular graft material is closed to100%, the inner diameter is almost unchanged with time. Mechanical performance test results showed that: 5# hydrogel reinforced pipes maximum compressive stress is 351.05 kPa,compression elastic recovery is 95.22 ± 0.66%; its axial stretch to 50%, the stress is 200.54 kPa,higher than swine carotid artery(185kPa), suture retention strength is 8.35 N, higher than the dog’s femoral artery(7.9N). Dynamic compliance of 5# hydrogel vascular graft material at a desired pressure is 3.54 ± 0.27%/100 mmHg, is very closest to human femoral arterial compliance value(3.8-6.5%/100mmHg). Thus, 5# alginate-polyacrylamide hydrogel vascular graft material can be used as high elastic and low swellable vascular graft materials.The biocompatibility study of 5# alginate-polyacrylamide hydrogel vascular materials found that: hemolysis of hydrogel vascular material is 0.38%, far less than the 5 percent by standard,indicating a smaller surface properties differences of the hydrogel and blood vessels, it will not destroy red blood cells. In vitro cytotoxicity test results showed that: alcohol sterilization and gamma sterilization of these two methods, the cell activity of alginate-polyacrylamide hydrogel materials were no significant difference; but the cell activity of 5# alginate-polyacrylamide hydrogel materials is low, indicating that the biological activity of this material is poor, we need to further improve research.