New Near Infrared Fluorescence Method For Monitoring And Exploring The Effects Of SO₂ Derivatives On Crops

Sulfur is the fourth important nutrient element in crops(next to nitrogen,phosphorus and potassium),which is highly significant to the yield and quality of crops.Leaf stomatal absorption of sulfur dioxide(SO2)in the atmosphere is the important ways to obtain sulfur nutrition in crops,it reacts with water in leaf tissue and immediately transforms into SO2 derivatives(SO32-and HSO3-).However,excessive absorption of SO2 by stomata will cause serious diseases to crops,such as chlorosis,crop yields reduction and even death.Therefore,it is of great significance to establish a method for the detection of SO2 derivatives in crop leaf tissue so as to treat crops in time.Currently,existing fluorescence detection methods for SO2 have limitations such as background fluorescence interference and low penetration.In this paper,two novel near-infrared fluorescent probes were developed to accurately detect SO2 derivatives in crop leaf tissues and explore the related toxicity mechanism.The specific works are as follow:1.In this study,we designed 7-diethylaminoazacoumarin to connect with quinoline salt through ethylene group,and successfully developed a ratiometric near-infrared fluorescent probe with high specific and sensitive response to SO2 derivatives,which overcame the interference of background fluorescence in leaf tissue.A novel fluorescence sensor system was developed to accurately monitor SO2 derivatives in crop leaf tissues.Fluorescence imaging experiments inferred that the probe could detect pre-introduced SO2 derivatives in the leaf tissue of crops(spinach,corn,carrot).The probe response to SO2 derivatives with the detection limits calculated to be 0.016 μM.Furthermore,the fluorescence intensity values(I516/I714)exhibited linear relationship with the concentration of SO2 derivatives ranged from 0 to 300 μM.The SO2(derivative)test strip was prepared by using the fluorescent probe,the application studies showed that the probe can quantitatively monitor SO2 and its derivatives in air and soil.2.In this study,we designed and developed a mitochondria targeted and immobilized ratiometric NIR fluorescent probe to explore the toxic mechanism of SO2 on crops.The probe exhibited a specific ratiometric NIR response to SO2 derivatives with high selectivity and sensitivity.And the detection limites was determined to be 0.512 μM.Fluorescence imaging in colon cancer cells(SW480)showed that the probe could not only be targeted into the mitochondria,but also be immobilized in the mitochondria to monitor the SO2 derivatives when the mitochondrial membrane potential was vanished.The leaf tissue of orychophragmus violaceus was taken as the research object,the results demonstrated that the concentration of SO2 derivatives in mitochondria of leaf tissue was closely related to the SO2 phytotoxicity to crops.The results showed that the damage of SO2 to mitochondria was an important way to cause crop toxicity.The results showed that the damage of SO2 to mitochondria was an important way to cause crop toxicity.