2.5. Column chromatography and nylon prefilter
Protein solutions spiked with aggregate were processed and applied to liquid column chromatography conducted using an AKTA avant 25 or an AKTA pure 25 (GE Healthcare) with the following types of chromatography resins. For mAb solutions, mixed-mode AEX1 (weak AEX of primary amine in combination with weak HIC of butyl group; Cellufine MAX IB), mixed-mode AEX2 (strong AEX with quaternary amine and phenyl group in combination with strong HIC; Capto adhere, GE Healthcare) and normal AEX (Cellufine MAX Q-h) were used. For plasma IgG solutions, mixed-mode AEX1 and normal AEX were used along with modified CEX1 (cross-linked cellulose with dextran sulfate; Cellufine MAX DexS-HbP), and modified CEX2 (sulfated cellulose; Cellufine Sulfate). All Cellufine resins were supplied by JNC Corporation.
Additionally, nylon prefilter Virosart Max Minisart (5 cm2 surface area, Sartorius), which is considered to be effective for removing aggregates, was used as a treatment for aggregate-spiked mAb solution.