Amphiphilic Polymer Capped Perovskite Compositing with Nano Zr‐MOF for Nanozyme‐Involved Biomimetic Cascade Catalysis

CsPbX(3) perovskite nanocrystal (NC) is considered as an excellent optical material and is widely applied in optoelectronics. However, its poor water stability impedes its study in enzyme‐like activity, and further inhibits its application in biomimetic cascade catalysis. Herein, for the first time, the oxidase‐like and ascorbate oxidase‐like activities of an amphiphilic polymer capped CsPbX(3) are demonstrated, and its catalytic mechanism is further explored. Furthermore, an all‐nanozyme cascade system (multifunctional CsPbBr(3)@Zr‐metal organic framework (Zr‐MOF) and Prussian blue as oxidase‐like and peroxidase‐like nanozyme) is constructed with a portable paper‐based device for realizing the dual‐mode (ratiometric fluorescence and colorimetric) detection of ascorbic acid in a point‐of‐care (POC) fashion. This is the first report on the utilization of all‐inorganic CsPbX(3) perovskite NC in biomimetic cascade catalysis, which opens a new avenue for POC clinical disease diagnosis.