The objective of this work is to study the feasibility of applying cellulose nanofiber membrane prepared by electrospinning as affinity membrane. Cellulose acetate (CA) solution (0.16 g/ml) in a mixture solvent of acetone/DMF/trifluoroethylene (3: 1: 1) was electrospun into nonwoven fiber mesh with the fiber diameter ranging from 200 run to 1 mu m. The CA nanofiber mesh was heat treated under 208 degrees C for I h to improve structural integrity and mechanical strength, and then treated in 0.1 M NaOH solution in H2O/ethanol (4:1) for 24h to obtain regenerated cellulose (RC) nanofiber mesh, which was used as a novel filtration membrane in this work. The RC nanofiber membrane was further surface functionalized with Cibacron Blue F3GA (CB), a general affinity dye ligand for separation of many biomolecules. The material's chemical and physical properties were studied by SEM, DSC and ATR-FTIR. Water filtration properties of the novel RC membrane were studied and compared with a commercial micro-filtration membrane. The CB derived RC nanofiber membrane has a CB content of 130 mu mol/g, and capture capacity of 13 mg/g for bovine serum albumin (BSA) and 4 mg/g for bilirubin. The membrane showed reusability after regeneration with elution buffer. Dynamic adsorption of BSA on the nanofiber membrane was studied by breakthrough curve measurements. (c) 2005 Elsevier B.V. All rights reserved.