Double sequential modifications of composite cryogel beds for enhanced ion-exchange capacity of protein

• Double-modification strategy was proposed to prepare ion exchangers.
• Double-modified composite cryogels possess large surface area and extended tentacles.
• Dynamic binding capacity of bovine serum albumin was 1.5–4.6 times enhanced.

Composite cryogel monoliths based on poly(2-hydroxyethylmethacrylate) (pHEMA) were fabricated by incorporating polymeric resin particles. The monoliths were sequentially modified by polyethylenimine (PEI) and diethylaminoethyl (DEAE). The novel composite material had rough pore walls and extended anion-exchange tentacles, which provided more binding sites for protein molecules. The dynamic adsorption capacity of bovine serum albumin (BSA) on the novel cryogel bed reached 11.2 mg/mL bed volume at a flow velocity of 8 cm/min, which was about 1.5–4.6 times higher than the cryogel beds obtained by single modifications. The capacity value was also much higher than the BSA capacities of cryogel beds reported in literature (1–6 mg/mL). The capacity decreased only slightly with increasing flow rate from 0.6 to 12 cm/min. The height equivalent to a theoretical plate of the composite beds was in the range 2–2.5 mm, changed indistinctively in a flow rate range 0.6–18 cm/min. Hence, the work has proved that the double-modification strategy was promising for enhancing protein adsorption capacity of cryogel monolith for high-speed protein chromatography.