 The study demonstrates oxidase-like and ascorbate oxidase-like activities of an amphiphilic polymer capped CSPBX3-paravskite nanocrystal and constructs a portable paper-based device for dual-mode detection of ascorbic acid in a point-of-care fashion using all-nanosyme cascade system with multifunctional CSPBBR3 at ZR-Metal Organic Framework, ZR-MOF, and Prussian Blue as oxidase-like and peroxidase-like nanosymes. This article was authored by Chiu Yuyi, Nshinyuan, Jin Shen, and others.