Biocatalytic CsPbX3 Perovskite Nanocrystals: A Self‐Reporting Nanoprobe for Metabolism Analysis

Abstract CsPbX 3 perovskite nanocrystals (NCs), with excellent optical properties, have drawn considerable attention in recent years. However, they also suffer from inherent vulnerability and hydrolysis, causing the new understanding or new applications to be difficultly explored. Herein, for the first time, it is discovered that the phospholipid membrane (PM)‐coated CsPbX 3 NCs have intrinsic biocatalytic activity. Different from other peroxidase‐like nanozymes relying on extra chromogenic reagents, the PM‐CsPbX 3 NCs can be used as a self‐reporting nanoprobe, allowing an “add‐to‐answer” detection model. Notably, the fluorescence of PM‐CsPbX 3 NCs can be rapidly quenched by adding H 2 O 2 and then be restored by removing excess H 2 O 2 . Initiated from this unexpected observation, the PM‐CsPbX 3 NCs can be explored to prepare multi‐color bioinks and metabolite‐responsive paper analytical devices, demonstrating the great potential of CsPbX 3 NCs in bioanalysis. This is the first report on the discovery of nanozyme‐like property of all‐inorganic CsPbX 3 perovskite NCs, which adds another piece to the nanozyme puzzle and opens new avenues for in vitro disease diagnostics.