The Research Of Small-caliber Polytetrafluoroethylene Artificial Vessel With Sulfonated Silk Fibroin Film By Low Temperature Plasma Treatment

1. BackgroundWith the socioeconomic rapid developments, people's living standard and health service have significant improvements, then the elderly population is increasing, since the reform and opening up. The statistical data of China National Committee On Aging showed:by the end of 2008, the population of aged 60 and above has reached 158 million, accounting for 12% of the total population in China. According to internationally accepted standards, China has entered the aging state. With this aging, cardiocerebral vascular disease incidence and mortality rates rose year after year. Coronary heart disease and other vascular occlusive disease have become a threaten to public health. The operations of Coronary Artery Bypass Surgery and Heart Arteriovenous Bridge Surgery are increasing annually. According to the statistics, approximately 850,000 cases of cardiac surgical revascularization were completed every year. Autologous blood vessels have good biocompatibility and blood compatibility,so they are always considered as an ideal natural vessels bridge material. However, the source is limited, and the autologous blood vessels are vulnerable to the vascular condition, if the performances are poor, it can easily make blood vessels narrow and insular, besides, a variety of surgical operations for acquisition will increase the trauma of the patient. Therefore, it is necessary to exploit an artificial blood vessel suitable for bypass or replacement surgery, especially the small-caliber.At present, using artificial blood vessels replace the aorta has achieved satisfactory effect, however, in the small arteries, veins, especially the diameter <6mm, no artificial material fully meets the high clinical application demand. The main problem is that the blood compatibility and anti-thrombotic properties are worse than autologous blood vessels, when contact with blood, the small-caliber vascular grafts will produce fibrin, make platelet deposition, then result in stenosis, vascular occlusion. Therefore, find the suitable materials and methods to exploit small-caliber artificial blood vessels, will not only meet the coronary artery bypass surgery and other vascular bypass surgery needs, but also can be used to develop new artificial valve and extracorporeal circulation pipings, which anticoagulant is not needed or only low-intensity anticoagulation, no doubt, it will promots the whole heart and vascular surgery fields. So, this study has strong practical significance.2. Objectives2.1 To study the preparation of composite vessels (small-caliber PTFE artificial vessel with sulfonated silk fibroin film by low temperature plasma treatment);2.2 To evaluate the blood compatibility of composite vessels.3. Materials and methods3.1 Argon Plasma pretreat the E-PTFE(expended Polytetrafluoroethylene) graft, analyse the contact angle changes before and after by the surface contact angle analyzer;3.2 The polytetrafluoroethylene artificial vessel was coated with silk fibroin membrane;3.3 The polytetrafluoroethylene artificial vessel coated with silk fibroin membrane was sulfonated by low Temperature Plasma Technology. Evaluate the effects of sulfonated by XPS surface element analysis; 3.4 Observe the surface morphology of the composite vascular and general blood vascular by scanning electron microscope;3.5 In vitro:Verify the blood compatibility of composite vascular and general blood vascular with blood platelet adhesion tests,dynamic cruor time tests and recalcification experiments, at the same time, detect the composite vascular's impact to red blood cells by hemolysis tests.4. Results4.1 In the contact angle'detection, after treated with low temperature plasma technology, the angle of artificial blood vessel was decreased gradually from 87.7°to 65.1°, then it reduced the surface energy of artificial blood vessels, increased the stability of silk fibroin membrane adhesion;4.2 The detecttion of sulfonic group using X-ray photoelectron spectroscopy (XPS)showed:the combined blood vessel was 2.85%, while, the general blood vessel was only 0.12%. The XPS spectrum also showed that most of the S atoms were sulfonic group(-SO3H);4.3 After platelet adhesion test, observe the composite blood vessels and general blood vessels by scanning electron microscope, we can see that platelets adhesion on the general blood vessel, the platelets was extended fully, flat and close to the surface of the material, but the platelets adhesion on the composite blood vessels only a little.4.4 The dynamic blood clotting test-showed:in absorbance-time curve, the combined blood vessel is above, and has a more moderate decline, experiences a longer time, the anticoagulant properties is better than the general blood vessels; Recalcification time of the combined blood vessel was 602.83±33.75 seconds, which was longer than the time of control blood vessel,480.00±33.27 seconds. The Independent-Samples Test showed that:the results were statistically significant differences(t=-6.349, P=0.000).5. Conclusions:5.1 Using the argon low temperature plasma technology can reduce the surface energy of ePTFE graft, increase the stability of silk fibroin membrane; Introduced the sulfonic group to the inner surface of ePTFE with hypothermia plasma sulfonated technology, the preparation is feasible;5.2 Making the silk fibroin membrane ePTFE graft sulfonated by hypothermia plasma sulfonated technology, can improve the blood compatibility and anti-clotting properties of the composite vessels.