▎ 摘　　要

Development of appropriate support for enzyme immobilization with approving loading capacity, stability and recyclable performance is a significant topic in enzyme chemistry. In this study, the hydrophilic polyethylenimine (PEI) modified magnetic graphene oxide (GO) composite (Fe3O4@PDA@GO-PEI) was fabricated and acted as an efficient solid support for the immobilization of dextranase to improve the stability and recyclable performance. The GO nanosheet component not only provided abundant binding sites for decorating PEI molecules and further increasing the loading capacity of immobilized dextranase, but also acted as a soft matrix for enhancing the stability of immobilized dextranase. In addition, in combination of the unique magnetic separation property, the recyclable ability of immobilized dextranase was further improved. The loading amount of immobilized dextranase on as-developed Fe3O4@PDA@GO-PEI was determined to be 305.1 mg g(-1), which was 1.61 times that on the Fe3O4@PDA-PEI without GO component. Moreover, the as-developed Fe3O4@PDA@GO-PEI-dextranase exhibited high immobilization efficiency (76.27%) and enzymatic activity (83.67%), improved stabilities in wide temperature conditions and pH solutions, and excellent reusability (85.78% of its initial activity after 20 cycles). These experimental results suggest that the immobilized dextranase is promising for various applications in biocatalytic engineering fields.