Chitosan Affinity Membrane Utilized For Endotoxin Removal In Protein Solutions

Endotoxin shows strong biological effects at very low concentrations in human beings and in many animals when entering the blood stream. Because of this toxicity, the removal of even minute amounts is essential for safe parenteral administration.Affinity membrane chromatography, the integration of membrane and affinity chromatography provides a number of advantages over traditional affinity chromatography with porous-bead packed columns, especially with regard to recovery of activity.Owing to the formation of endotoxin micelles and vesicles, microfiltration membrane adsorbers are particularly effective since mass transfer restrictions are almost absent in the flow-through pores. With comparison to two kind of ligands, it is shown that both electrostatic and hydrophobic interactions contribute to the association of ligands and endotoxin.Membrane utilized for endotoxin removal namely chitosan affinity membrane was prepared by using Poly(vinylidene fluoride) (PVDF) hollow fiber membrane as support. The application of the membrane in endotoxin removal in BSA and lysozyme solutions was investigated. The factors affecting endotoxin removal such as ionic strength, pH value and flow rate were investigated, and the results were discussed.PVDF hollow fiber membrane was first treated by alkali solution, then the hydrophilia-modified membrane was cross-linked with chitosan, so the chitosan affinity membrane was prepared. The nonspecific adsorption of the treated membrane was decreased. The character of the treated membrane was stable. And the hydrophilicity was greatly improved.When the membrane was utilized for endotoxin removal in BSA solution, the ionic strength can be chosen between 0.2 and 0.4, and the pH value can be chosen between 5 and 7. The infection of the temperature was not obvious and the flow rate can be chosen as your command. Under the optimal conditions, the removal efficiency of endotoxin was over 85% and recovery of BSA was over 95%.When the membrane was utilized for endotoxin removal in lysozyme solution, the ionic strength can be chosen about 0.2, and the pH value can be chosen about 11. The concentration of the endotoxin can be lowered. It can be below 0.04Eu/mL.L-Lys was tried as the ligand, but the result was not ideal.