Dual-site functionalized NIR fluorescent material for a discriminative concentration-dependent response to SO2 in cells and mice

Abstract

Sulfur dioxide (SO₂), as an important anti-oxidant and gaseous signaling molecule, plays fundamental roles in the regulation of intracellular signaling and cell death cellular bioenergetics. The accurate determination of the SO₂ levels in an organism is a critical step in establishing its biological functions. Therefore, there is a high demand for developing efficient analytical methods for monitoring the wide range of concentration changes of SO₂ in living systems. Herein, for the first time, we have successfully constructed a dual-site functionalized NIR fluorescent material (NIR-SP), which is capable of monitoring low concentrations of SO₂ with red fluorescence responses and high concentrations of SO₂ with blue fluorescence enhancements. Further studies absolutely confirmed that the discriminative response was due to the fact that the reactivity of the unsaturated CC double bond (site I) in NIR-SP was superior to that of the aldehyde group (site II). Furthermore, detection in a concentration-dependent manner was demonstrated by fluorescent imaging in cells and mice. We envision that this strategy would lead to insights into SO₂ concentration-dependent biological effects and cell signals.