Construction Of Novel Sulfur Dioxide Fluorescent Probes And Their Bioimaging Applications

As we all know,SO₂ is a kind of air pollutant,which can do great harm to human body,and may cause respiratory diseases,nervous system disease,cardiovascular diseases and even cancer.On the other hand,as a biological gas signaling molecule,SO₂plays an important role in regulating a wide range of physiological processes,including regulating vasodilation,anti-hypertension,regulating cardiovascular function,and participating in intracellular redox balance.However,its production process and mechanism of action in many physiological activities are still unclear.Therefore,it is of great significance to design and develop new SO₂ fluorescent probes for the detection of SO₂ and its derivatives in physiological environments.Therefore,this research reasonably designed and constructed three types of SO₂ fluorescence probes with different performance,and studied their optical properties and applications in biological imaging.The specific research content is as follows:（1）By introducing a benzothiazole quaternary ammonium salt onto 2-（2’-hydroxyphenyl）-benzothiazole（HBT）,a new ratiometric SO₂ fluorescence probe SEW-SO₂-1 Based on the ESIPT mechanism was developed.The fluorescence change from red to yellow is appeared through Michael addition reaction of probe with SO₂ and its derivatives.By measuring the relevant spectra,we found that the reaction of the probe with SO₂ derivatives has the characteristics of rapid reaction,high selectivity,dual channel fluorescence detection,and large fluorescence changes.In addition,the probe has good biocompatibility,and it has been applied to imaging SO₂ derivatives in zebrafish.（2）Based on the protection and deprotection of levulinic acid,a novel near-infrared fluorescence probe SEW-SO₂-2 for detecting SO₂ and its derivatives was constructed.The probe can react with SO₂ and its derivatives and activate a near-infrared fluorescence emission with a large Stokes shift based on the dual mechanism of ESIPT and ICT.Besides,the probe has good specificity and low cytotoxicity.And then,the probe has been applied to fluorescence imaging of exogenous and endogenous SO₂ in cells and zebrafish.（3）Based on the classic ICT mechanism,a highly sensitive SO₂ near-infrared fluorescence probe SEW-SO₂-3 with mitochondrial targeting ability was reasonably constructed.When the probe reacts with SO₂ and its derivatives,the original A-π-A structure of the probe will be destroyed and transform into a product with D-π-A structure,which turn on near-infrared fluorescence emission based on the ICT effect.By measuring the relevant spectra,we found that the probe is very sensitive to SO₂ and its derivatives,characterized by rapid reaction,low detection limit,and high selectivity.And the probe has good biocompatibility and mitochondrial localization ability.Subsequently,the probe was used for imaging of endogenous and exogenous SO₂ in cells and living mice.In addition,the probe has also been applied to imaging inflammation in cells,tissues,and live mice.