ZIF-8 encapsulated-enzymes integrated nanozyme cascade biocatalysis platform for the colorimetric sensing of glucose and lactose in milk

Cascade biocatalytic reactions have a wide range of applications, especially in the filed of food analysis. Herein, a multi-enzyme composite (ZGGPC) was prepared by in-situ synthesis of Zeolite imidazole framework-8 (ZIF-8) on Prussian blue (PB) modified carbon cloth (CC). The composite encapsulated both glucose oxidase and β-galactosidase simultaneously during the synthesis process. CC and ZIF-8 showed high loading capacity for PB and natural enzymes, respectively. And ZIF-8 also displayed excellent tolerance in protecting enzyme activity under extreme conditions. Based on the cascade biocatalysis, ZGGPC was used to detect glucose and lactose by colorimetric method with detection limits of 1.2 μM and 1.7 mM, respectively. Benefiting from the merits of low cost, easy preparation, and good stability, the sensing system was used to successfully determine glucose and lactose in different milk samples. The present cascade biocatalysis system is hopeful to develop simple and efficient sensing platforms for food analysis.