A dual-targeted organelles SO2 specific probe for bioimaging in related diseases and food analysis

Sulfur dioxide (SO2), as the main member of reactive sulfur species (RSS), it is mainly produced in mitochondria and involved in a variety of activities at the cellular level. Excessive inhalation of SO2 could cause respiratory tract damage, cardiovascular disease and even cancer. The mitochondrial and lysosomal as two important organelles, their interactions (fusion and contact) are important for maintaining eukaryotic homeostasis. Some study indicated that SO2 is active in the above interaction process. In this work, benzopyranium salt unit was constructed as fluorophore I, where O+ was the mitochondrial target site, and naphthalimide was linked to morpholine to construct fluorophore II, where morpholine was the lysosomal target group. Studies have shown that the probe has a good performance in targeting both mitochondria and lysosomes. And after the reaction with SO2, FRET was broken, resulting in red quenching, and green emitting, which made it can detect SO2 with a ratiometric response. Cells cultured with nystatin showed decreased red and green fluorescence increased, indicating that the autophagy of mitochondria produced SO2. In addition, synthesized control reagents (targeting lysosomes alone and responding to SO2) from no signal to gradually enhanced blue fluorescence, indicating that SO2 produced by mitochondria is transferred to lysosomes. What's more, it could monitor the changes of SO2 concentration under heat stroke. More importantly, it could quantitatively detect sulfite concentration in Yuba and crystal sugar.