Preliminary Research Of Textile-based Gelatin Hydrogel Small-diameter Vascular Graft Materials

With aging of population and development of people’s living standard, incidence of blood vessel diseases is increasing. Artificial vascular replacement is the most direct and effective way to cure human’s vessel diseases. Large or medium diameter vascular grafts have been successfully applied in replacement and bypass operation. However, when smaller blood vessel diameter (<6mm) or lower blood flow velocity is needed for surgery, satisfactory results have not been obtained using artificial blood vessels as substitutes.With advantages of easy-processing, excellent mechanical properties and controlled inner diameter, textile materials such as polyester, silk, polyurethane, ePTFE are studied in recent years, but surface modification are usually needed because of their dissatisfactory biocompatibility. Hydrogels are widely used materials for tissue engineering, and they are advantageous in that they have three-dimensional network structure, contain large amount of water, resemble ECM and have outstanding biocompatibility. In this paper, shaping feasibility of coating hydrogel on surface of textile-based tube and the basic properties were explored, laying foundation for finally obtaining ideal mechanical and biocompatibility properties that meet requirements of small-diameter vascular grafts.The first part:a kind of gelatin hydrogel with epoxide as crosslinking agent was prepared by exploring the preparation condition, and the properties were characterized. Results of preparation condition were:temperature60"C, catalyst NaCl2%, gelatin concentration≥6%, mass ratio of gelatin to PGDE1-4. FT-IR spectrum showed that PGDE was induced onto gelatin chains by opening the rings on both sides. As showed in SEM:gelatin hydrogel had smaller pore size and more compact structure after PGDE cross-linking. Swelling and mechanical testing results indicated that, PGDE cross-linked gelatin hydrogel had lower swelling ratio, excellent elastic resilience, lower stiffness, improved flexibility and strength compared with pure gelatin hydrogel. The compressive mechanical characteristics of PGDE cross-linked gelatin hydrogel werein the same order of magnitude as genipin and EDC cross-linked gelatin hydrogel, and PGDE cross-linked gelatin hydrogel had higher elastic resilience than genipin cross-linked gelatin hydrogel. As demonstrated in biocompatibility test, hydrogel had good blood compatibility.The second part:In order to primarily discuss the adhension situation between fabric and hydrogel, as well as themechanical properties after recombination in wet condition, plane textile-based gelatin hydrogel materials were prepared. To begin with, plane mold was designed and processed to prepare textile-based gelatin hydrogel materials, then shaping techniques of composite materials were studied by using selected fabrics and optimized gelatin hydrogel.Mechanical properties of textile-based hydrogel materials were tested and results are as follows. The tensile strength of textile-based gelatin hydrogel materials were mainly contributed by fabrics. Fabrics with proper hydrophilic and porosity were beneficial to improve the adhensive force between fabric and hydrogel and to prepare ideal textile-based hydrogel materials.The third part:with originally designed and processed tubular mold, as well as results of exploration of plane textile-based gelatin hydrogelmaterials,tubular textile-based gelatin hydrogel small-diameter vascular graft materials were prepared in wet condition. The morphology and mechanical testshowed that:tube wall is uniform and smooth; fabric and hydrogel combined well; elastic recovery was above90%; compliance values were1.03-2.16%/100mmHg, though the value were lower than natural blood vessels(compliance values of human femoral artery are3.8-6.5%/100mmHg), yet higher than woven Dacron(0.80%/100mmHg)å'ŒePTFE(0.22-0.60%/100mmHg) which are currently clinically applied as vascular grafts.In all, preparation condition of PGDE cross-linked gelatin hydrogel was researched and optimized hydrogels were obtained. Also with results of exploration of plane textile-based gelatin hydrogelmaterials, tubular textile-based gelatin hydrogel small-diameter vascular graft materials with excellent elastic recovery and compliance were successfully prepared, thus providing underpinnings for further researching small-diameter vascular graft with ideal mechanical properties and biocompatibility...