▎ 摘　　要

In this work, a novel type of functionalized magnetic graphene oxide (MGO) nano-sheets which have the ability to capture His-tagged CotA laccase was synthesized. N alpha,N alpha-Bis(carboxymethy1)-L-lysine hydrate (NTA-NH2) was attached on MGO then chelated with Ni2+ and Cu2+ separately. The Cu2+-chelated MGO (MGO-NTA-Cu2+) exhibited the highest adsorption capacity of 177 mg/g-support when compared with both MGO and Ni2+-chelated MGO (MGO-NTA-Ni2+) which exhibited an adsorption capacity of 49.9 and 145 mg/g-support, respectively. CotA laccase immobilized on MGO-NTA-Cu2+ nano-sheets showed the highest activity recovery when compared with that immobilized on MGO-NTA-Ni2+ nano-sheets. The catalytic properties of MGO-NTA-Cu-CotA laccase were significantly improved in comparison with those of the free laccase. MGO-NTA-Cu-CotA laccase showed efficient decolorization for Congo Red (CR), and the decolorization rate reached 100% after 5 h reaction at 60 degrees C and pH 8. Furthermore, MGO-NTA-Cu-CotA laccase retained 89.4% of its initial activity after 10 consecutive cycles. Together these results indicated that the Cu2+ chelated MGO nano-sheets are promising support for efficient CotA laccase immobilization for environmental and industrial applications under high temperature and alkaline condition. (C) 2017 Elsevier B.V. All rights reserved.