Polyethylenimine modified poly(ethylene terephthalate) capillary channeled-polymer fibers for anion exchange chromatography of proteins

• The surface of polyethylene terephthalate (PET) capillary channeled-polymer fibers are aminated with polyethylenimine.
• Cross-linking with 1,4-butanediol diglycidyl ether (BUDGE) increases the anion exchange capacity.
• Surface modification does not degrade column permeability nor the mass transfer properties of proteins.
• Protein separation quality is not sacrificed at high linear velocities (>400 cm min−1).

Native poly(ethylene terephthalate) (PET) capillary-channeled polymer (C-CP) fibers have been previously studied as stationary phases for reversed phase and affinity protein separations. In this study, surface modified PET C-CP fibers were evaluated for the anion exchange separation of proteins. The native PET C-CP fibers were aminated using polyethylenimine (PEI) followed by a 1,4-butanediol diglycidyl ether (BUDGE) cross-linking step. Subsequent PEI/BUDGE treatments can be employed to further develop the polyamine layer on the fiber surfaces. The PEI densities of the modified fibers were quantified through the ninhydrin reaction, yielding values of 0.43–0.89 μmol g−1. The surface modification impact on column permeability was found to be 0.66 × 10−11 to 1.33 × 10−11 m2, depending on the modification time and conditions. The dynamic binding capacities of the modified fiber media were determined to be 1.99–8.54 mg mL−1 bed volume, at linear velocities of 88–438 cm min−1 using bovine serum albumin as the model protein. It was found that increasing the mobile phase linear velocity (up to 438 cm min−1) had no effect on the separation quality for a synthetic protein mixture, reflecting the lack of van Deemter C-term effects for the C-CP fiber phase. The low-cost, easy modification method and the capability of fast protein separation illustrate great potential in the use of PEI/BUDGE-modified PET C-CP fibers for high-throughput protein separation and downstream processing.