A ratiometric NIR fluorescent probe for simultaneous detection of H2S and viscosity: Applications in environmental monitoring and bioimaging

• A mitochondria-targeted NIR probe ( T-N ) was synthesized through a one-step strategy. • T-N achieves ratiometric H₂S sensing and viscosity monitoring via independent emission channels in a single probe. • It enables dual-channel imaging of cellular H₂S/viscosity dynamics with high mitochondrial specificity. • T-N- based strips allow instrument-free, semi-quantitative H₂S detection in environmental waters, beverages, and food spoilage scenarios. Hydrogen sulfide (H 2 S), a critical gasotransmitter governing physiological functions, presents significant environmental and food safety hazards at aberrant concentrations. Concurrently, mitochondrial viscosity serves as a vital biomarker for cellular pathologies. To address the unmet need for precise dual-parameter monitoring, we engineered a mitochondria-targeted near-infrared (NIR) ratiometric fluorescent probe, T-N , enabling simultaneous and discriminative detection of H 2 S and viscosity through discrete emission channels. The probe exhibits ultrarapid response (<30 s), exceptional sensitivity, and superb selectivity against competing analytes. Leveraging H 2 S-triggered chromogenic shifts, T-N -immobilized test strips facilitate instrument-free, semi-quantitative assessment of food spoilage, validated across environmental waters and industrially relevant beer samples. Moreover, T-N achieves synchronous dual-channel imaging of endogenous/exogenous H 2 S and viscosity dynamics in live cells, with verified mitochondrial localization. This work establishes a versatile sensing platform for tracking H 2 S and viscosity in interconnected environmental, food safety, and biomedical contexts.