Electrospun regenerated cellulose nanofiber affinity membrane functionalized with protein A/G for IgG purification

The aim of this work is to prepare protein A/G functionalized electrospun regenerated cellulose (RC) nanofiber mesh as affinity membrane for immunoglobulin G (IgG) purification. Cellulose acetate (CA) nonwoven nanofiber membrane was prepared by electrospinning, followed by heat treatment and alkaline treatment to obtain RC nonwoven nanofiber membrane. After oxidization of the RC membrane by NaIO4, protein A/G was covalently immobilized on the membrane, giving an affinity membrane capable of specifically capturing IgG molecules. Physical and chemical properties of the affinity membrane were characterized. Surface chemistry of the membranes during the membrane modification process was monitored with XPS and ATR-FTIR. Oxidization degree of the RC membrane was optimized to get a high ligand binding capacity without too much loss of mechanical strength for handling of the material. Ligand (protein A/G) amount immobilized on the RC membrane oxidized for 9 h was measured as 30 μg/mg and the membrane's IgG binding capacity was measured as 18 μg/mg. The IgG purification ability of the affinity membrane was evaluated with BSA as a model impurity. Five layers of the cellulose affinity membrane were packed into a spin column to separate IgG from an IgG/BSA mixture solution. SDS-PAGE analysis showed that the BSA was completely removed after the purification.