Accurately monitoring of sulfur dioxide derivatives in agricultural crop leaf tissues by a novel sensing system

Accurately monitor SO2 derivatives in agricultural crop leaf tissues is imperative, but it is still limited. A fluorescent sensing system with the characteristic of ratiometric near-infrared (NIR) fluorescence response to analyte is conducive to applying in agricultural crop leaf tissues. Herein, we rationally constructed 7-diethyl-amino-azacoumarin conjugated quinolinium hybrid, CQ-1, as the first fluorescent sensing system to monitor SO2 derivatives in ratiometric NIR response manner in agricultural crop leaf tissues. CQ-1 exhibited specific and sensitive ratiometric NIR response to SO2 derivatives, with detection limits calculated to be 0.016 mu M. Moreover, the fluorescence ratios (I-516/I-714) of the CQ-1 displayed linear relationship with the concentrations of introduced SO2 derivatives from 0 to 300 mu M. Fluorescence imaging experiments revealed that CQ-1 was able to detect pretreated SO2 derivatives in agricultural crop leaf tissues. Significantly, quantitative detection of SO2 derivatives in leaf tissues which were assimilated by stomata from SO2 polluted air was successfully conducted. The sensing system developed herein will be used as an effective tool to accurately monitor the subtle changes of SO2 derivative level in various agricultural crops.