Protein adsorption and elution performances of porous hollow-fiber membranes containing various hydrophobic ligands

Phenyl and butyl groups as hydrophobic ligands for protein binding were appended to the poly(glycidyl methacrylate) chain grafted onto a pore surface of a porous polyethylene hollow-fiber membrane with a pore size of 0.2 mu m. A hydrophobic ligand density of the modified membranes from 0.5 to 2.5 mmol/g was obtained, while pure water flux of the hollow fibers was 80% that of the original hollow fiber. Favorable kinetics, wherein an increasing permeation rate provides an increasing binding rate of bovine serum albumin (BSA), were observed in the permeation 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 fibers. A -NH(CH2)(3)CH3-group-containing membrane exhibited electrostatic interaction as well as hydrophobic interaction with BSA. A -OC6H5-group-containing membrane exhibited the highest elution percentage of 83% by permeating an (NH4)(2)SO4-free buffer.