Preparation And Blood Compatibility Of Fiber Biomimetic Composite Film On Engineering Vascular Scaffolds

As the development of molecule biology, the third generation biomaterial which is tissue engineering come forth. The hotspot of tissue engineering are the compound of different materials; the import of growth gene and the bionics to the structure of the cell extracellular matrix's configuration. The reaction between cell and biomaterial exterior has close relation with the performance of material exterior. So it is effective to establish biologic coating on blood vessel stent to prevent restenosis and thrombus. By electrospinning technique, polyurethane nanofibers can be produced on 316L stainless steel whose nanofiber structure is similar with the cell extracellular matrix and basement membrane. Then through static self assembled, the chitosan and Carboxymethyl chitosan are preparated on electrospinning PU fiber coating, which enhance the biology compatibility.The main research content are the influence parameter of electrospinning's enactment. We mainly investigates the influence of solvent on the surface of polyurethane film. The results indicate that the character of solvent will affect the range of electrospinning concentration evidently. The range of concentration are 4%-15% (tetrahydrofuran as solvent), and 8%-22% (N,N-dimethylformamide as solvent) respectively. With tetrahydrofuran as solvent, it is found that when the concentration rises, the diameter of fiber will decrease at first and then increase in the range of optimal concentration 6%-12%. The uniform and compact fibers with the average diameter of 350nm, are made by the mixed solvent which is better than the simplex. In addition, Through water contract measurement, the relationship between the coating's surface micrograph and Hydrophilicity/hydrophobicity is found. In the process of static self-assembled, the concentration of CS /CMC and the number of layer are investigated. The results show that the water contract angle of CMC increase as the number of self-assembled layer increase. The sawtooth figure which is the relationship of water contract angle and layer shows that the static self-assembled method work. The maximal concentration of CS and CMC are 0.4% and 0.8%. Because the surface of the multilayer coating become blurry if the concentration of the CS and CMC are increased which is not accord with the demand of tissue engineering stent.When the stent coating are prepared, we estimate the blood compatibility through adhesion of Platelet experiment and O.D.-Time curve. It is indicated that the platelet easily adhere on the fiber whose diameter are below 1000nm. However micron fibers adhere little. Through static self-assembled method, the composite multi-layered film which is containing chitosan and carboxymethyl chitosan is prepared. Then platelet adhere less obviously and O.D.-Time curve show that the surface modification enhance the film's blood compatibility.The experiment in this article show that the model of this stent coating is adapt to the tissue engineering. However it is necessary to do some cell compatibility experiment. So this coating deserved continuing investigation.