Fabrication And Properties Of The Electrospun Poly (Lactide-co-glycolide)/Silk Fibroin Shell-core Composite Tubular Scaffold

Tissue engineering blood vessel has been become a hot research currently. Electrospinning technology as one of the most convenient ways to produce nanofibers possesses unique advantage. The fibers produced by it with high surface area to volume ratio and porosity can imitate the structure of extracellular matrix. It's conducive to cell adhesion, proliferation, nutrient transport and metabolism. Therefore, fabricating tissue engineering blood vessel with electrospinning has broad prospects.As natural biological materials, silk fibroin has favorable bio-compatibility. It's conducive to culture cell; As synthetic polymer materials, PLGA possesses favorable bio-compatibility, bio-mechanical properties and biodegradability. It's propitious to improve the bio-mechanical properties of the scaffolds and control the degradation rate.In this thesis, a shell-core composite tubular scaffold was fabricated by multi-electrospinning using a high-speed rotating mandrel-type as the collector with silk fibroin as a core layer and PLGA as a shell. Firstly, in order to confirm the optimumtechnical parameters of the electrospun PLGA, the author observes the morphology of the fibers by SEM. And the microstructure, porosity, bio-mechanical properties and degradation performance in vitro of PLGA tubular scaffold were studied; Secondly, the morphology, micro-structure, porosity, water-dissolved rate, bio-mechanical properties and tissue compatibility of electrospun silk fibroin tubular scaffold were researched; Thirdly, the author studied blood compatibility of the electrospun silk fibroin fiber scaffold, using SEM, FTIR to characterize its morphology and micro-structure; using hemolysis tests, platelet adhesion tests and coagulation test to characterize its blood compatibility; Finally, the PLGA/SF shell-core composite tubular scaffold was fabricated under the optimum technical parameters via electrospinning. Morphological, porosity, water-dissolved rate and bio-mechanical properties of the composite scaffold were studied.The study results showed that: The optimum technical parameters of electrospun PLGA layer(shell layer) were set as follows (listed in the order of voltage, electrode distance, flow rate and mandrel rotating speed):25kV, 15cm, 0.1ml/h and 1500r/min. The electrospun PLGA tubular scaffold possessed favorable bio-mechanical properties and adjustable degradation rate; The electrospun SF tubular scaffold had good morphology, high porous structure and good histocompatibility; The hemolytic rate of the electrospun SF fiber scaffold was 4.5%, which fulfils with the needs of hemolysis test on biomaterials; Plasma grafting of heparin, C-sulfonic acid lactoneand and blending with heparin for electrospinning can improve the electrospun SF fiber scaffold's blood compatibility. It made the SF scaffolds have a good anti-clotting properties; but the bio-mechanical properties( such as tensile strength, suture retention strength) of SF scaffolds were poor. It needs to combine with other materials to improve the bio-mechanical properties.The electrospun PLGA/SF shell-core composite tubular scaffold had high porosity and excellent biomechanical properties, Its tensile strength, burst pressure strength and suture retention strength were 1.06MPa, 131.3kPa and 1.21N/needle, respectively. All of the bio-mechanical properties reached the criterion for vascular graft. After ethanol treatment, the bio-mechanical properties of the composite scaffold increased significantly and water-dissolved rate decreased remarkable. The papers provided an experimental basis for the composite tubular scaffold used as tissue engineering blood vessel.