Construction And Application Of Fluorescent Probes For Specific Recognition Of Viscosity And Reactive Sulfur

In the existing analysis,fluorescent probes have attracted the interest of many scientists and carried out in-depth research in various fields due to their advantages of high sensitivity,good selectivity,detection limit of nanomolar level,in situ measurement,visual measurement and non-destructive measurement.The design of a novel fluorescent probe for the detection of target analytes in biological environment has important reference significance for the study of physiological and pathological mechanisms.Viscosity is an important part of cell microenvironment and a basic biomechanical parameter related to tissue function and pathological state.The viscosity varies greatly in different regions of the cell,so it also affects the diffusion of each region,including mass transfer,signal transduction,interaction between biochemical substances,diffusion of metabolites and electron transfer.Hydrogen Sulfide（H₂S）and Sulfur Dioxide（SO₂）are important small molecules produced in biological environment and organic bodies.According to many reports,H₂S and SO₂have played an important physiological role in organisms as small gas messenger molecules.Proper H₂S and SO₂ can maintain redox homeostasis in vivo,regulate vascular dilation in vivo,prevent and reduce tissue injury,etc.However,H₂S and SO₂,when in excess,can affect embryonic development and have been linked to Parkinson’s disease,arterial hypertension and neurological disorders.Therefore,it is necessary to develop effective tools for the specific detection of viscosity and active sulfur molecules,which are also important for promoting disease prevention and clinical diagnosis.Three fluorescent probes containing different ICT（TICT）mechanisms were designed.Their structures and relative molecular masses were characterized by NMR and mass spectrometry.The response performance of these three probes to viscosity,SO₂ and H₂S and their co-localization performance to mitochondria were probed by spectroscopic tests and cell imaging tests.Overall,a series of meaningful research results were obtained.The thesis study contains the following main components:In the first part of the work,a mitochondrial viscosity probe MF-V1 was designed and synthesized to target mitochondria in the absence of Mitochondrial Membrane Potential（MMP）and to respond sensitively to viscosity changes in mitochondria,enabling high-fidelity imaging of intracellular mitochondrial viscosity changes under normal and depolarizing conditions.This enables high-fidelity imaging of intracellular mitochondrial viscosity changes under normal and depolarized conditions.In the second part,a single-molecule probe,Mito-MG,was designed and synthesized to target mitochondria and respond to both viscosity and sulfur dioxide,which enables a fast response to sulfur dioxide by disrupting the conjugated structure through Michael addition,and to viscosity by limiting the free rotation of the intramolecular rotor.The probe has the advantages of low detection limit（0.24Μm）,large Stokes shift（95 nm）,and fast response.In the third part,a small molecule probe Mito-GF,which targets mitochondria and responds to both viscosity and hydrogen sulfide,was designed and synthesized to specifically recognize H₂S by linking 2,4-dinitrobenzene as the H₂S recognition site.And it was used to detect viscosity changes in mitochondria by using the intramolecular restriction mechanism of TICT.