Chitosan/coarse filter paper composite membrane for fast purification of IgG from human serum

Membrane-based affinity chromatography has been extensively investigated for biomolecule purification and immunoadsorption. However, recently developed composite membranes have been found to be limited in their liquid flow rates. A chitosan/cellulose composite membrane is reported here, providing a large liquid flow rate through the membrane and good mechanical properties. This new membrane was prepared by coating a 0.5% chitosan solution containing 1% acetic acid and 15% polyethylene glycol (PEG) onto coarse filter paper. The flux of water through the membrane reached 8.9 ml/(min cm2) at a pressure drop of 5 psi. The adsorption of human IgG on the immobilized protein A composite membrane was further investigated under both equilibrium and dynamic conditions. The equilibrium adsorption did not follow the Langmuir model, but fitted the Freundlich–Langmuir composite equation nicely. A maximum equilibrium binding capacity of 33.20 mg/cm3 membrane and dissociate constant of 8.60 mg/ml were found. Dynamic binding capacity of 14.75 mg/cm3 membrane was obtained. Sample loading flow rates did not influence the dynamic binding capacity of IgG from human serum. However, increasing sample recirculation time increased the dynamic binding capacity of IgG from human serum by 60% over 40 min, compared with the operation without recirculation. Low non-specific binding was observed on both the protein A coupled and uncoupled chitosan/cellulose composite membranes. Sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE) showed that the purified IgG from the human serum offered higher purity than the commercial IgG product. The results in this study indicate that the affinity chitosan/cellulose membrane has a great potential in fast purification of biomolecules.