Synthesis of polymer-functionalized β-cyclodextrin, Mg2+ doped, coating magnetic Fe3O4 nanoparticle carriers for penicillin G acylase immobilization

Based on the beneficial effects of magnesium ions on biomolecules, it was first introduced into enzyme immobilization carriers to promote the comprehensive performance of immobilized enzymes in repeated use. Firstly, Fe3O4 nanoparticles (NPs) were prepared by the inverse microemulsion method, then, Mg2+ was doped in the process of coating beta-cyclodextrin (beta-CD) on the surface of Fe3O4 NPs. Afterward, through acetal reaction, glutaraldehyde (GA) was grafted to the material's surface to obtain Mg2+-Fe3O4 @ beta-CD-g-GA NPs, and covalent bond immobilization of Penicillin G acylase (PGA) was realized by the Schiff base reaction of the carriers' aldehyde group and PGA's amino group. After optimization of process conditions, the results show that the performances of the immobilized PGA achieve the best, when the concentration of the enzyme solution is 3.00 vol%, pH is 8.0, the immobilization time is 30 h, and the immobilization temperature is 37 C. Its enzyme activity recovery (EAR), enzyme activity (EA) and enzyme loading capacity (ELC) are 95.6%, 31997 U/g, 110 mg/g, respectively. Lastly, the operational stability, reusability, and storage stability of Mg2+-Fe3O4 @ 8-CD-g-GA-PGA NPs were researched. Relative to free PGA, immobilized PGA has better operation stability and storage stability. After 11 repeated uses, the immobilized PGA still has 56% of the initial vitality, and the carrier recovery (R-e) is 86.6%.