Nonwoven meshes composed of polysulphone (PSU) ultrafine fibers (diameter 1-2 mu m) were fabricated via electrospinning technique and then surface modified towards development of a novel affinity mernbrane. After the electrospinning, the PSU fiber mesh was heat treated under 188 degrees C to significantly improve the mechanical strength of the fiber mesh. For surface modification, carboxyl groups were introduced onto the PSU fiber surfaces through graffing co-polymerization of methacrylic acid (MAA) initiated by Ce(IV) after an air plasma treatment of the PSU fiber mesh. Toluidine Blue O (TBO), a dye, which can form stable complex with carboxyl groups, was used as a model target molecule to be captured by the PMAA grafted PSU fiber mesh. The adsorption isotherm and rate of the TBO were studied. Further more, the carboxyl groups on the PMAA grafted PSU fiber mesh can be used as coupling sites for immobilization of other protein ligands. Bovine serum albumin (BSA) was chosen as a model protein ligand to be immobilized into the PSU fiber mesh with a capacity of 17 mu g/mg. The Surface modification processes were verified by XPS and ATR-FRIR spectroscopy. Filtration analysis showed that the nonwoven fibrous membrane has much smaller pressure drop (Delta P = 0.7-1.5 psi) and higher flux compared with conventional micro-filtration membranes. The electrospun PSU fiber mesh developed in this work is a potential candidate material to be used as affinity membranes. (c) 2005 Elsevier B.V. All rights reserved.