A mitochondria-targeted near-infrared fluorescent probe for detection and imaging of HSO3- in living cells

[Display omitted] •A near-infrared fluorescent probe A1 was designed and synthesized for HSO3- detection and cell imaging.•Fluorescent probe A1 exhibited good mitochondria targeting ability.•Probe A1 showed good selectivity and high sensitivity for HSO3-.•Probe A1 exhibited good performance on monitoring the variation of exogenous/endogenous HSO3- in mitochondria of living cells. Sulfur dioxide, an essential gas signaling molecule mainly produced in mitochondria, plays important roles in many physiological and pathological processes. Herein, a near-infrared fluorescent probe, A1, with good mitochondria targeting ability was developed for colorimetric and fluorescence detection of HSO3-. Probe A1 has a conjugated cyanine structure that can selectively react with HSO3- through the nucleophilic addition. The reaction with HSO3- destroys the conjugated structure of probe A1, resulting in fluorescence quenching, and accompaniedby color change of probe A1 solution from purple-red to colorless. Probe A1 showed high selectivity and good sensitivity to HSO3- in PBS. And the limit of detection was calculated to be 1.28 and 0.037 μM for colorimetry and fluorescence spectrophotometry respectively. In addition, probe A1 mainly entered the mitochondria in living cells, and was successfully used for imaging the exogenous/endogenous HSO3- in cells. These results suggest the potential applications of probe A1 in biological systems.