PVDF Affinity Membrane Grafted Amino Acids And Removal Of Endotoxin

Endotoxin is a cell wall component of gram-negative bacteria, and it could show strong biological effects entering the human or animal's blood system, at very low concentrations. Therefore, it is very necessary to remove endotoxin from medicinal products and blood.Affinity adsorption is wieldy used for separation of protein with high recovery and activity, and it has attracted attentions on endotoxin removal for excellent specific selectivity. The affinity membrane, as a kind of affinity membrane chromatography, compared to traditional packed column chromatographic, could deal with more products and be easy to enlarge. So the affinity membrane is more suitable for practical use.In this paper, we firstly used L-serine (Ser), L-arginine (Arg) and L-asparagine (Asn) as ligands separately, polyvinylidene fluoride (PVDF) hollow-fiber membrane as the bare membrane,1,6-hexanediamine as the spacer arm to make new types of affinity membrane for endotoxin removal from human plasma. Comparing the endotoxin removal capacity of three kinds of affinity membranes, we found that PVDF-Ser affinity membrane was the best one. For 40ml human plasma sample with endotoxin concentration of 0.42EU/ml, the clearance efficiency of self-made PVDF-Ser affinity membrane module could reach 48.3% at 1ml/min velocity. The endotoxin adsorption capability was 0.027EU/cm2 with little effect on other biochemical indicators, the loss of total protein (including the various types of enzyme) was 14.9% and the recovery rate of albumin was 92.4%.Then FTIR, XPS and SEM were used to characterize the surface of membranes. The effects of operation parameters, such as pH value, ionic strength and flow rate on the endotoxin adsorption capacity of the PVDF-Ser affinity membrane and the affinity adsorption kinetics were investigated.Then, amplified lab-made PVDF-Ser affinity membrane modules were used in animal experiments. The results showed that PVDF-Ser affinity membrane had good blood compatibility and the amplified module could effectively remove endotoxin from experimental pig, it could reduce concentrations of tumor necrosis factor(TNF-a) and interleukin(IL-6), thereby the inflammatory was weakened.