| In clinical medicine, there are many medical instruments which must contact with blood. When blood reaches variant materials, many negative reaction will happen. They include: plasma proteins absorption and denature, protein adheration and distrotion, cell adheration and activity. Then blood coagulation, hemolysis will appear. PEU is known for its biocompatibility in therapy, and has been prepared in many forms for clinical. PEU is always directly implanted into the body, but it will be supported by anticoagulant matters.so it how to characterize the compatibility of PEU and use the results of its property to direct our research is so important in anticoagulant biomaterials designs. In this study, our aim is to research the surface property of structure modified PEU,and recalcification time test, platelet adheration test, the rate of hemolysis test,BSA adheration test, et al,to characterize its biocompatibility.To screen out biomaterials which have good biocompatibility, the biocompatibility of structure modified PEU have been evaluated. The main works and conclusions are included as follows: (1)Research the Property of new composite material: Firstly,the anticoagulation of new modified PEU has been checked. The results of recalcification time showed that recalcification time of structure modified PEU was above 7 minutes and 3 times of blank PEU. PEU and heparin were linked with covalent bond and the bioactivity of heparin was preserved. According suface caculation,the heparin content was 1.277μg/cm2, the release rate of heparin content from the surface in 24 hours was 8.2%. It reached the standard of heparinized anticoagulate biomaterials. (2) Biocompatible test: The biocompatible test of new PEU film was performed. The result of platelet adhesion showed that structure modified PEU adhered little platelet about 1.7×1010/L and lower to the blank PEU about 3.5×1010/L. Regarding hemocyte, two materials'hemolysis rate was blow 5%., and hemolysis rate of structure modified PEU was 3.52% This value meet standard of biomedical materials.The other mentioned test were used evaluate the biocompatibility of materials from histological level to cellular level including pyrogen experiment, skin irritating test, introcutaneous stimulation test, acute systemic toxicity test and MTT test. All od these tests showed structure modified PEU good biocompatibility no less than blank PEU. (3) Protein adhesion test: Protein adsorption test of new PEU film was performed. It showed that the adsorption ratio of BSA on biomaterial surface can improve in according to the hydrophilic of material surface. And The statical isotherms adsorption model of BSA had been gotten, 331.524 101 1.847 10qCC??= ? ××.SEM anlysis showed that surface modified PEU adsorbed much BSA than the blank PEU.At 37℃and the density of BSA at 40μg/m, the BSA adsorption of structure modified PEU is about 148.891μg/ml,far more blank PEU about 70.250μg/ml. (4) Antibacterial test: Through observing the E.coli adhesion among structure modified PEU segments and blank PEU, it found that structure modified PEU segments which contained heparin on its surface has good antibacterial ability than blank PEU.It showed that heparin and hydrophilic of material surface can enhance its antibacterial ability and we can make full use of this characteristics for the purpose of the prophylaxis of biomaterial infection.The maximum adhesion number of E.coli on structure modified PEU surface was 2.69×103 cfu/cm2,lower to the blank PEU about 4.27×105 cfu/cm2. We can conclude from the above research that structure modified PEU biomaterial integrated the excellent mechanic properties of the noumenal PEU materials and the wonderful anticoagulant properties of modificatory heparin material, whose prospect of applications must be very broad.
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