Synthesis Of Ratiometric Aggregation-Induced Emission Probe And Its Application In Detection And Imaging Of Disease Markers

Alzheimer's disease,non-alcoholic fatty liver disease and acute colitis can cause abnormal expression of disease markers such as cholinesterase and active sulfur in the body during the occurrence of the disease.Precisely monitoring the dynamic changes of disease markers in the pathological environment is of great significance for the early diagnosis of diseases and revealing their chemical biological roles in related diseases.However,due to the complex and diverse biological environment,it is still a huge challenge to accurately monitor the dynamic changes of various actives and biological macromolecules in living systems.Fluorescent probes are powerful tools for monitoring the dynamic changes of disease markers in vitro and in vivo due to their high sensitivity,good selectivity,and noninvasiveness.However,typical organic fluorescent probes are susceptible to aggregation-caused quenching(ACQ)in physiological environments.At the same time,a single signal output method is not conducive to accurate monitoring in living organisms,and these shortcomings greatly limit their real-time monitoring in living cells and living bodies.Aggregation-induced emission(AIE)proposed by Tang's groupcan effectively avoid luminescence quenching induced by ACQ.In addition,monitoring the analyte through two or more signal outputs can reduce the influence of the external environment.In this paper,the following three ratiometric fluorescent probes with AIE properties were designed and synthesized:(1)AIE-based lysosome-targeted ratiometric fluorescent probe for polysulfide imaging in mice with acute ulcerative colitisHydrogen polysulfide(H₂S_n,n>1),as the directly oxidized form of hydrogen sulfide,plays an important role in maintaining redox balance in intestinal diseases such as ulcerative colitis(UC).In addition,H₂S_n in lysosomes is closely related to autophagy,metabolism and autophagy.We report a two-stepsynthesis of a ratiometric AIE probe TCFPB-H₂S_n with lysosome targeting.TCFPB-H₂S_n achieve H₂S_ndetection and imaging in cell lysosomes and acute colitis mice after two nucleophilic reactions with H₂S_n to release a fluorophore.Notably,this work is the first to explore imaging of the dynamic changes of endogenous H₂S_n in mice with acute ulcerative colitis,which provides a powerful detection tool for hydrogen polysulfide in the study of inflammatory bowel disease.(2)AIE-based ratiometric fluorescent probe for butyrylcholinesterase imaging in mice with nonalcoholic fatty liver diseaseButyrylcholinesterase(BCh E)is an important human biomarker associated with liver and neurodegenerative diseases,and it is important to developfluorescent probes that can image BCh E in vitro and in vivo.Unfortunately,most fluorescent probes based on changes in a single fluorescence intensity are susceptible to environmental interference.Therefore,we report a readily available ratiometric fluorescent probe with aggregation-induced emission(AIE)properties(TCFPB-BCh E)for ratiometric imaging of BCh E.We explained the AIE mechanism of the probe molecule by DFT calculation,and also confirmed the high selectivity of the probe TCFPB-BCh E to BCh E by molecular docking.In addition,TCFPB-BCh E showed excellent sensitivity to BCh E(LOD=39.2 ng/m L).Finally,we successfully achieved ratiometric imaging of BCh E in cells,serum and mice with nonalcoholic fatty liver disease.These results suggest that TCFPB-BCh E holds promise as a powerful analytical tool for studying butyrylcholinesterase in basic medicine and clinical applications.(3)Large Stokes shift ratiometric fluorescent probes based on AIE and ESIPT for imaging acetylcholinesterase in vitro and in vivoAcetylcholinesterase(ACh E)is closely related to Alzheimer's disease(AD),and the overexpression of ACh E causes the loss of acetylcholine in the brains of Alzheimer's patients,which affects the transmission of nerve signals in the body.No ACh E probes with ratiometric aggregation-induced emission characteristics have been reported so far.Therefore,we developed a ratiometric AIE fluorescent probe(DPHP-ACh E)for selective imaging of ACh E in vitro and in vivo.Furthermore,we investigated that oxidative stress over-activated ACh E activity in glioma cells.After activation by ACh E,fluorophores undergoing excited-state proton transfer(ESIPT)exhibit large Stokes shift(188 nm),red-to-near-infrared(NIR)fluorescence emission,and aggregation-induced emission(AIE)properties.