Immobilization of trypsin by thermo-responsive hydrogel for the affinity separation of trypsin inhibitor

A series of thermo-responsive hydrogels were synthesized from N-isopropylacrylamide (NIPAAm), glycidyl methacrylate (GMA), and N, N-dimethyl acrylamide (DMA). The effect of the different monomer ratios of GMA/DMA in the copolymeric hydrogel on the swelling behaviors, physical properties, and drug release behavior was investigated. Results showed that the swelling ratio in deionized water increased with an increase of content of DMA in the copolymeric hydrogel. However, the compressive modulus, crosslinking density, and mechanical strength decreased with increasing DMA content in the copolymeric hydrogel. In addition, the influence of the copolymeric composition on the immobilization of enzyme on the poly(NIPAAm-co-GMA-co-DMA) hydrogel which was used as a support to immobilize trypsin was also investigated. The result showed that the copolymeric hydrogel showed a good immobilized capacity of trypsin. The immobilized trypsin as a ligand of affinity chromatography having fifty three percent activity of trypsin inhibitor in the crude extract of sweet potato can be recovered by affinity chromatography. The molecular weights of the purified trypsin inhibitors are more than 20 kDa by SDS-PAGE.