Development of an AND Logic‐Gate‐Type Fluorescent Probe for Ratiometric Imaging of Autolysosome in Cell Autophagy

The concomitant detection of two biological events facilitates the highly selective and sensitive analysis of specific biological functions. In this article, we report an AND logic‐gate‐type fluorescent probe that can concurrently sense two biological events in living cells: H₂O₂ accumulation and acidification. The probe exhibits a unique fluorescence sensing mechanism, in which a xanthene fluorophore is oxidatively transformed to a xanthone derivative by H₂O₂, thereby resulting in a clear dual‐emission change. This transformation is significantly accelerated under weak acidic conditions, which enables the selective and sensitive detection of H₂O₂ production in an acidic cellular compartment. This unique sensing property was successfully applied to the ratiometric fluorescence imaging of autolysosome formation in selective mitochondrial autophagy (mitophagy), which highlights the utility of this novel probe in autophagy research.