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.