Preparation And Characterization Of Polysulfone Asymmetric Hollow Fiber Membranes Used In Bioartificial Liver

During the past decades, hollow fiber membranes have been widely used forextracorporeal blood treatment ranging from hemodialysis (artificial kidney),plasmapheresis to oxygenator (artificial lung). These techniques of bloodpurification are all designed to remove harmful substances from the blood or correctthe blood composition through diffusion and convection. Remarkable progress hadbeen made during the past twenty years, particularly in the field of hemodialysis.However, conventional blood purification treatment is limited in detoxifcation. Withthe advance of cell separation technique, it becomes possible to develop of abioreactor with anabolic functions. Recently the development of bioartificial liver(BAL) has attracted more and more interesting. While research on BAL systems isstill in its infancy, the ultimate goal is to develop a sophisticated BAL suitable forclinical applications. The goal of this thesis is to prepare and character a serious ofhollow fibers used in BAL systems.In this thesis, the preparation of hollow fiber membranes was carried out firstly bydry-wet spinning technique to a quaternary system including polysulfone (PSf), asolvent, a nonsolvent and an additive. Experiments showed that control of the amoutof nonsolvent could eliminate macrovoids within the membrane. The effect ofpolymer concentration on the crosss-section structure of membranes was also discussed. Finally, three kinds of hollow fiber membranes were prepared, and thecorresponding dopes contained 10% PSf, 12% PSf and 15% PSf, respectively. Theprepared membranes had a single skin and integral asymmetric structure with anentirely reticulated structure free of macrovoids. The characterization involvedsurface pore size; pore distribution; porosity; roughness; mechanical performance;wettability and liquid permeability (Lp). The results showed that, with the increasingof the PSf concentration in dope, (1) the average pore diameters were decreasing andthe pore distributions became narrow; (2) surface and bulk porosities weredecreasing; (3) internal surfaces roughnesses were increasing and the externalsurfaces roughnesses were decreasing; (4) tensile strengthes were increasing andbreaking elongation rates were decreaing; (5) contact angle and Lp were bothdecreaing.When membranes are used in contact with cell, the cell compatibility of hollowfiber membranes are of primary importance. In this thesis, some aspect of cellcompatibility of hollow fiber membranes was evaluated and discussed, includingcytotoxictiy, cell adherence and cell growth. The cytotoxictiy experiment showed thatthe membranes qualified for cell to contact with. The experiments of endothelialcells growing on the membrane surface indicated that the membranes were suitablefor cell adherence and growth.The above results indicate that the membranes have potential for use in the BALfield.