Surface Modification Of Blood Purification Dialyzer Membrane By Antithrombotic Immobilization And The Study Of Its Antithrombotic Properties

Background:Blood purification treatment is a very important technology for the treatment of critical ill patients. In many this patients are often accompanied by haemorrhage tendency. But blood purification treatment must be dealed with anticoagulant. So, it is restricted by adverse reactions of anticoagulant in Blood purification to treatment with haemorrhage tendency patients.Surface of the dialyzer membrane which contact with blood is main resource of thrombogenicity, Improving the blood compatibility of the membrane may reduce the generation of thrombogenicity. We still haven't a kind of dialysis membrane which could independent of usage of systemic anticoagulant, we know that coating anticoagulant onto the surface of the membrane could improved blood compatibility. Vascular endothelial cells are the best blood compatible interface for the blood flowing, and antithrombotic agents secreted by the cells also play an important role in preventing blood from thrombosis. As we know, grafting and cross linking are useful technology in modification. So, simulating of the endothelial cells, grafting the anticoagulant on the membrane surface may improve the efficiency of anticoagulation and cut down the dosage of systematically anticoagulant. Objective:We will construct a new type of blood purification dialyzer membrane with goog blood compatible by grafting and cross linking technique. The new type of membrane have more efficiency function of anticoagulation.The first part:Preparing and studying of the anticoagulant modified membraneMethod:We got covalent immobilization of argatroban membrane by successive treatments of friedel-crafts reaction and amino-modification, and subsequent chemical cross linking of argatroban with bifunctional linker molecules. To confirm every step, we use dyeing test of Methylene Blue, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). To determine the characteristices about surface of membrane, we use water contact angle test, canning electron microscopy (SEM) and atomic force microscopy (AFM), X-ray diffraction (XRD) and the release of argatroban from the surface of modified membrane. To evaluate the blood compatibility of modified membrane, hemolysis test, albumin adhesion test and platelet adhesion test were conducted. The plasma recalcification time, the activated partial thromboplastin time (APTT), prothrombin time (PT) and thrombin time (TT) were conducted to evaluate the anticoagulation characteristics of modified membrane. Results:The modification process is confirmed by dyeing test of Methylene Blue, XPS and FTIR. The modification of argatroban decrease the contact angle for water and enhance the hydrophilic property of modified membranes, while morphology characteristics and crystallinity of membranes have no changed. Hemolysis test showed that hemolysis rate of samples were lower than 5%. The two adhesion tests showed that the number of albumins adhering to the membrane was more significantly in modified membranes, while the number of platelets was fewer significantly. The plasma recalcification time and APTT of modified membrane were significantly longer. But, there are no effect on PT and TT.The second part:Preparing and studying of the anticoagulant modified dialyzer membraneMethod:We got covalent immobilization of argatroban blood purification dialyzer membrane by using the method of modified plain membrane, and confirmed by XPS. To evaluation of the security and biocompatibility of modified dialyzer membrane, we use cytotoxicity test of cells (MTT), sensitization test, stimulation test, acute toxicity test, hemolysis test and pyrogen experiment. To evaluate the anticoagulation characteristics of modified dialyzer membrane, we use the simulate treatment of hemodialysis. Results:The modification process is confirmed by XPS. The argatroban modifed dialyzer membrane does not have any cytotoxicity, sensitization, stimulation, acute toxicity and pyrogen. Hemolysis test showed that hemolysis rate of samples were lower than 5%. After the simulate treatment of hemodialysis, the modified dialyzer membrane has lower coagulation.Conclusion:1. Plain membrane and dialyzer membrane could be modified by grafting and cross linking technique successfully.2. Argatroban can be covalent immobilization on the surface of plain membrane and dialyzer membrane.3. The modification on the membrane surface enhance the hydrophilic property of membrane, and didn't change the surface characteriatices.4. Modified Plain membrane and dilyzer membrane has good property of biocompatibility.5. Modified plain membrane and dilyzer membrane has good property of anticoagulation.