Preparation and characterization of thiophilic cryogels with 2-mercapto ethanol as the ligand for IgG purification.

In this study, thiophilic cryogels were prepared by two different approaches and they were used in purification of IgG from aqueous solutions and human plasma. In the first approach, poly(2-hydoxyethyl methacrylate) [PHEMA] cryogel disks were prepared. The PHEMA cryogel disks were activated by divinylsulfone (DVS) and 2-mercapto ethanol was attached. In the second approach, poly(2-hydroxyethyl methacrylate-etylene glycol dimethacrylate) [P(HEMA-EGDMA)] beads were synthesized and 2-mercapto ethanol was attached to the beads as a thiophilic ligand. In order to increase the surface area, P(HEMA-EGDMA)/PHEMA composite cryogel disks were prepared by embedding the P(HEMA-EGDMA) beads into PHEMA cryogels. Both the thiophilic PHEMA (T-PHEMA) cryogel disks and the thiophilic P(HEMA-EGDMA)/PHEMA [T-P(HEMA-EGDMA)/PHEMA] composite cryogel disks were characterized by Fourier transform infrared spectroscopy, surface area measurements, elemental analysis, swelling tests and scanning electron microscopy. The effects of salt concentration, pH, temperature, initial IgG concentration were analysed for IgG adsorption from aqueous solutions in batch mode. When lyotropic salt, Na2SO4, was used, the adsorption capacity was 27.5 mg/g and 68.7 mg/g for T-PHEMA and the T-P(HEMA-EGDMA)/PHEMA composite cryogel disks, respectively. 1.0 M NaCl was used as desorption agent. The change in adsorption capacity was not remarkable for a repetition of adsorption-desorption cycle ten times. Both the thiophilic cryogel disks and the thiophilic composite cryogel disks were also successfully used for IgG isolation from human plasma. The purity assayed by SDS-PAGE was 89%. The adsorption capacities were 74.8 mg/g and 137.4 mg/g in human plasma samples for the T-PHEMA cryogel disks and the T-P(HEMA-EGDMA)/PHEMA composite cryogel disks, respectively.