Study On Preparation And Characteristics Of Affinity Biomaterial To Remove Endotoxin

Bacterial endotoxin (ET) plays a key role in the pathogenesis of endotoxemia and multiple organ dysfunction syndrome which have not been successfully dealt with pharmacologically. Polymyxin B(PMB)can bind endotoxin specifically and can inactivate endotoxin. However, PMB has been restricted in clinical application because of its toxic effect on the kidney and it is not easy to remove PMB from blood.In the research, the ligand, PMB was immobilized onto polystyrene microbeads as a kind of affinity adsorbent to selectively removal ET from plasma and its capability of removing endoxin, adsorbing protein in plasma and its influence on blood viscosity were studied.(1) The polystyrene beads with a certain length arm were prepared by coupling linear spacer. Then the PMB ligands were immobilized on the spacer arms-containing polystyrene beads by glutaraldehyde to prepare the adsorbents. The results indicated that the polystyrene beads immobilized PMB were obtained through FT-IR spectrum and other biochemical analysis.(2) The factors that could influence the immobilized ligand density were studied. The results indicated that the optimum conditions of coupling PMB ligands through its –NH2 to polystyrene beads by glytaraldehyde are: the initial concentration of 4mg/ml of PMB is more efficient than the higher xoncentration; the concentration of glutaraldehyde which activated polystyrene beads is 5%, PH is 7.0, and the coupling reaction time is at least 4 hours.(3) The quantitative method to detect endotoxin was set up and factors that could influence the testing method were also studied. The results indicated that the detection method was influenced strongly by plasma but slightly by pH and temperature. (4) The capability of the polystyrene microbeads to selectively remove endotoxin and the relationship between removing endotoxin and hemoperfusion time were studied in vitro. The results indicated the ability of removing endotoxin increased with the increasing amount of polystyrene microbeads and the best result was achieved at 40min after hemoperfusion。(5) The effects of the polystyrene microbeads on total protein in plasma in hemoperfusion were studied and the results indicated that the affinity adsorbent had slight effects on the total amount of protein in plasma and the adsorptive rate is less than 10%.(6) The ability of the affinity adsorbents to improve blood viscosity was studied. The results indicated that blood became more viscid with adding endotoxin and blood viscosity could be improved by hemoperfusion with the adsorbents.The experimental results indicated that the adsorbents could selectively remove endotoxin, adsorb little protein in plasma and could improve blood viscosity. Therefore, it is possible to apply the PMB immobilized polystyrene microbeads as a kind of hemoperfusion material to therapy endotoxemia as an assistant approach in clinical treatment.