Design,Synthesis And Application Of Fluorescent Probes For Singlet Oxygen And Fluorescent Probes For Simutaenously Discriminating Lipid Droplets And Protein Aggregates

Singlet oxygen(¹O₂)is an excited oxygen molecule with high energy,which is an important reactive oxygen species(ROS).¹O₂ has important physiological functions in living organisms,such as killing invasive bacteria,regulating biological cell signal and inducing gene expression.Moreover,recent studies have shown that ¹O₂ is the main molecule in photodynamic therapy(PDT)for cancer treatment.However,the excessive production of ¹O₂ in living organisms will cause a variety of biological molecules(such as DNA,protein,lipid,etc.)to be oxidized,leading to the occurrence of various diseases,including cardiovascular disease,neurodegenerative disease,diabetes and so on.Therefore,it is necessary to establish an accurate,rapid and quantitative analysis method for the detection of ¹O₂ in living organisms.Aging is a complex physiological process,which often leads to the decline of the function of tissues and organs,and then leads to the occurrence of various diseases.Exploring the mechanism of aging will help to delay aging,prolong life span and improve the quality of life for the elderly.Lipid droplets(LDs)and protein aggregates(PAs)play an important role in the process of aging.In order to dessect the interaction mechanism of LDs and PAs in aging,it is urgent to develop an effective analytical method that can simultaneously discriminate LDs and PAs in living organisms.The fluorescence analysis method based on fluorescent probe can be used for imaging of biological molecules with high spatial and temporal resolution in non-invasive way.Therefore,the fluorescent probe is especially suitable for real-time detection of ¹O₂ and simultaneous discrimination of LDs and PAs.In this dissertation,we have constructed a fluorescent probe to detect ¹O₂ and a fluorescent probe to simultaneous discrimination of LDs and PAs.The specific research works are as follows:1.Construction of ratiometric fluorescent probe for accurately detecting the concentration of ¹O₂ in living organism.The probe per se showed bright blue fluorescence(450 nm).However,the fluorescence color of the probe changed from blue to yellowish green(565 nm)after the treatment with ¹O₂,thus showing a ratiometric fluorescence response.Moreover,the fluorescence intensity ratio(I₅₆₅/I₄₅₀)has a good linear relationship with the concentration of ¹O₂(0-4 m M).Selective and competitive studies showed that the probe could specifically detect ¹O₂.p H and water content studies found that the probe could detect ¹O₂ in physiological environment.The kinetic study displayed that the probe could detect ¹O₂ rapidly.Moreover,the probe has been successfully applied to monitor the endogenous and exogenous ¹O₂ concentrations in biological cells.2.Development of a novel dual-functional fluorescent probe to simultaneously monitor the LDs and PAs during aging.By intriguingly designing the unique mechanism of hydrogen bond regulating the rotation of single bond or the efficiency of intramolecular charge transfer(ICT),the probe can specifically respond to LDs and PAs in red fluorescence channel and near infrared(NIR)fluorescence channel,respectively.Notably,upon imaging the LDs and PAs levels in intestine tissue of mice by the probe,we find that the concentrations of PAs increase significantly in the process of aging,accompanying with the buildup of LDs.Moreover,the interaction of LDs with PAs during aging was clearly noted.These results inferred that the PAs were positive correlated with the aging process,while LDs can be formed correspondingly to eliminate the generated PAs.