Performance of polyacrylamide-alginate-based cryogel for IgG purification from bovine serum by IMAC

Abstract

Immobilized metal ion affinity chromatography (IMAC) was used for bovine immunoglobulin G (bIgG) separation. Monolithic cryogel based on polyacrylamide (PAAm), alginate (Alg), and allyl glycidyl ether (AGE) was prepared at sub-zero temperature and then iminodiacetic acid (IDA) was covalently bound to this structure. The cryogels were characterized by swelling, compression, and surface area tests, SEM, FTIR, porosity, ligand density, and flow rate. Transition metal ions Cu(II) and Ni(II) were chelated on the PAAm-Alg-AGE-IDA cryogel aiming to explore their performance in the separation of bIgG from bovine serum by IMAC. The binding of bIgG in different buffers systems and pH values from aqueous and bovine serum solutions were investigated on both chelated and control (IDA-cryogel) monoliths to optimize adsorption conditions. The best condition was observed at 25 mmol/L MOPS pH 6.5. Breakthrough curves and elution showed that the IDA-Cu(II)-cryogel adsorbed higher amount of total protein (32.24 mg/g) than IDA-cryogel (26.4 mg/g); however, the latter showed higher bIgG purity (88%). The experimental isotherms were best described by the Langmuir–Freundlich model, obtaining maximum adsorption capacity of 148.09 mg of bIgG/g and 51.50 mg of bIgG/g for IDA-Cu(II)- and IDA-cryogel, respectively, and dissociation constant of magnitude order of 10−6 mol/L for both cryogels.