Bienzymatic nanoreactors composed of chloroperoxidase–glucose oxidase on Au@Fe3O4 nanoparticles: Dependence of catalytic performance on the bioarchitecture.

The operational stability of chloroperoxidase (CPO) was considerably enhanced by coupling with glucose oxidase (GOx) because H 2 O 2 could be generated in situ from glucose and oxygen. In this paper, a CPO–GOx nanoreactor was fabricated on the surface of Au@Fe 3 O 4 nanoparticles through layer-by-layer assembly using the specific avidin–biotin interaction. The X-ray diffraction data indicated the presence of both Fe and Au in the Au@Fe 3 O 4 carrier. The Au@Fe 3 O 4 displayed a uniform core/shell nanostructure, whereas the nanoparticles of the bienzymatic reactor were larger than the carrier. The catalytic activity of CPO was highly dependent on the structure of the enzymatic nanoreactor. The activity of Au@Fe 3 O 4 –GOx (inner)–CPO (outer) was 15.5% higher than that of Au@Fe 3 O 4 –CPO (inner)–GOx (outer). Moreover, Au@Fe 3 O 4 –GOx–CPO exhibited better thermostability. Au@Fe 3 O 4 –GOx–CPO retained 53.2% of its initial activity after incubation for 1.0 h at 60 °C and 30.4% of its initial activity after 18 h at 50 °C. Au@Fe 3 O 4 –GOx–CPO had good reusability. It retained more than 62.4% of its activity after the 12th cycle. This was attributed to the cage-like structure in Au@Fe 3 O 4 –GOx–CPO, which could effectively prevent the removal of the enzyme molecules from the carrier. [ABSTRACT FROM AUTHOR]