PROTEIN ADSORPTION AND ELUTION PERFORMANCES OF POROUS HOLLOW-FIBER MEMBRANES CONTAINING VARIOUS HYDROPHOBIC LIGANDS

Phenyl and butyl groups as hydrophobic ligands for protein binding wer e appended to the poly(glycidyl methacrylate) chain grafted onto a por e surface of a porous polyethylene hollow-fiber membrane with a pore s ize of 0.2 mu m. A hydrophobic ligand density of the modified membrane s from 0.5 to 2.5 mmol/g was obtained, while pure water flux of the ho llow fibers was 80% that of the original hollow fiber. Favorable kinet ics, wherein an increasing permeation rate provides an increasing bind ing rate of bovine serum albumin (BSA), were observed in the permeatio n mode because of the negligible diffusional mass-transfer resistance of the protein to the hydrophobic ligand during convective transport. Equilibrium binding capacity of BSA in a phosphate buffer (0.07 M, pH 7.4) containing 2 M (NH4)(2)SO4 was 30 mg/g of the modified hollow fib ers. A -NH(CH2)(3)CH3-group-containing membrane exhibited electrostati c interaction as well as hydrophobic interaction with BSA. A -OC6H5-gr oup-containing membrane exhibited the highest elution percentage of 83 % by permeating an (NH4)(2)SO4-free buffer.