A Hemicyanine-BODIPY-Based Dual-Channel Fluorescent Probe for Simultaneous Sensing of Sulfur Dioxide Derivatives and Viscosity

Sulfur dioxide (SO2) derivatives and viscosity are important yet interrelated indicators in both food safety and disease pathologies. However, existing detection methods struggle to simultaneously assess these two parameters. To address this limitation, we developed CyB-Mito, a mitochondria-targeted fluorescent probe that allows dual-channel detection of both parameters. The probe consists of a hemicyanine unit conjugated to a BODIPY core via a reactive double bond. This single structural motif enables two distinct response mechanisms: nucleophilic addition of SO2 derivatives disrupts the double bond, inducing a turn-on green fluorescence signal (limit of detection, LOD = 12.6 nM), while in high-viscosity environments, restricted intramolecular rotation of the same double bond produces a marked enhancement of red fluorescence (LOD = 1.4 cP). CyB-Mito enables the concurrent monitoring of SO2 derivatives and viscosity in food and beverage samples, living cells, and zebrafish. In addition, it supports real-time, on-site detection of SO2 derivatives in food products through a smartphone-integrated platform. Notably, in cellular models of diabetes, CyB-Mito revealed a pathological correlation between mitochondrial viscosity and SO2 levels. Collectively, this work establishes CyB-Mito as a versatile dual-functional tool with promising applications in food safety and biomedical research.