| Nitrocellulose (NC) membrane is the fist commercialized micro-porous membrane, which was widely used in the last twenty years in the fields of biology and medicine because of its strong absorption ability for biological macromolecules.The NC membranes were prepared by casting and coagulation, phase separation induced by vapor phase, and dry-cast process in the paper. The mechanisms of membrane formation and absorption of proteins were studied. The main experiments and results were summarized as follows:NC membrane was prepared by casting and coagulating solutions of the polymer with three different solvents: DMAc, DMSO and AC, respectively. The effects of different solvents and content in coagulation on the morphology of the membrane were studied. The results indicated that the inter-diffusion of the solvent-nonsolvent system affected the membrane structure significantly. The membrane casted with DMSO as solvent showed the best performance. The skinless membrane with the highest porosity was obtained by immersing the polymer solution in 30% DMSO coagulation bath.By adding glycerin in the casting solution of nitrocellulose and, the cellular surface structure was fabricated via phase separation induced by penetration of nonsolvent from vapor phase. The results showed that amount of glycerin, the time of phase inversion induced by water vapor and relative humidity of the membrane-forming had important effects on the structure of membrane. The pore sizes on the glass-surface of membranes were between 5 to 8μm.The network NC membrane was prepared by dry-cast process. Acetone was used as solvent. The non-solvent additives were ethanol, isopropyl alcohol, and water. The results showed that the weight fractions of solvent and non-solvent and the circumstance of membrane-forming had important effects on the structure of membrane. Under certain condition, the network NC membrane with pore sizebetween 0.7 to18.6μm was obtained.The mechanism of adsorption of NC membrane to protein was researched. The result obtained from the static adsorption experiments showed that the free enthalpyof the adsorption reaction of protein onto the membrane surface was -6.799KJ mol-1,the activation energy was 7.293 KJ mol-1. It could be predicted that the adsorptionof proteins mainly attributed to Van der waals interaction, hydrophobic bonding and hydrogen bonding. The adsorption appeared to follow a typical Langmuir adsorption isotherm under optimal conditions. The maximum amount of adsorbed proteins was reached at pI, and the amount of adsorption increased with the increase of ionic strength and decrease of pore size of membrane.The application of NC membrane obtained by dry-cast was studied. Recombinant allophycocyanin (rAPC) with a purity of 98% was transferred onto NC membrane to form the immuno-affinity membrane. Based on the specific immunological reaction of antigen and antibody, rabbit anti-APC antibodies were purified from the rabbit polyclonal serum. The amount of absorbed antibody was 5.79 mg/g membrane analyzed with ELISA methods. And the purity of antibodies was up to 98 % analyzed with SDS-PAGE, which offered a novel immunological affinity membrane for the separation of antibodies.
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