Construction of Efficient Bienzyme Cascade Catalytic System by"Yolk-shell"Structure
This work proposes a bio-composite,ZIF-8@GOx-CPO@ZIF-8,which is constructed by"Yolk-shell"characteristic metal-organic framework(MOF)for specific division of glucose oxidase(GOx)and chloroperoxidase(CPO)by encapsulating them at different compartments.The structure of"Yolk-shell"can provide nano-proximity effect for encapsulated enzymes.H12O2 generated in situ by GOx immediately starts the enzymatic reaction of adjacent CPO,effectively reducing the diffusion resistance of reactants and the decomposition and escape of H2O2,and avoiding the interaction of the two enzymes during reuse.Compared with the free enzymes in the homogeneous buffer,the cascade catalytic efficiency of ZIF-8@GOx-CPO@ZIF-8 is improved.Owing to the shielding effect provided by the MOF,the thermal stability and organic solvent tolerance of the enzyme is also greatly improved.The"Yolk-shell"structure also effectively inhibits the leakage of enzyme molecules during the reuse process of the material.After 20 reuses,the bio-composite ZIF-8@GOx-CPO@ZIF-8 can keep 72％of the initial cascade efficiency.The cascade reaction of GOx-CPO can generate HC1O,which is applied in efficient decolorization of azo dye and fresh-keeping of fruit.The decolorization of azo dye orange G(0.3 mmol/L)was almost completed in only 15 min with 98％decolorization efficiency by 1 mg/L of ZIF-8@GOx-CPO@ZIF-8.ZIF-8@GOx-CPO@ZIF-8 bienzyme cascade catalytic system is efficient,stable,mild and green with great application potential.
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