Preparation of supermacroporous cryogels with improved mechanical strength for efficient purification of lysozyme from chicken egg white.

A novel, facile, and robust strategy was proposed to increase the pore size and mechanical strength of cryogels. By mixing the monomers of acrylamide and 2-hydroxyethyl methacrylate as the precursor, a monolithic copolymer cryogel with large interconnected pores and thick pore walls was prepared. Hydrogen bonding between the two monomers contributed to the entanglement and aggregation of the copolymers, thickening the pore walls and resulting in larger pore sizes. Analysis via mercury porosimetry demonstrated that the interconnected pore diameter of the copolymer cryogel ranged from 10-350 µm, which was far larger than that of the cryogels from one monomer (10-50 µm). Additionally, the thicker pore walls of the copolymer cryogel improved its mechanical strength. Affinity cryogels were prepared through covalent immobilization using Tris(hydroxymethyl)aminomethane as a coupling agent, and the affinity binding of lysozymes on Tris-cryogel was evaluated by the Langmuir isothermal adsorption with the maximum adsorption capacity of 360 mg/g. Compared with that of the Tris-cryogels produced from one monomer, the copolymer Tris-cryogel exhibited higher adsorption capacity and lysozyme purity, when the chicken egg white solution flowed solely driven by gravity. This work provides a new avenue for designing and developing supermacroporous cryogels for bioseparation.