Synthesis And Bioimaging Application Of PH Fluorescent Probes

Intracellular pH is an important factor in physiological activities.Abnormal pH can induce many diseases.Therefore,detecting intracellular pH is of great importance for physiology and pathology.In recent years,fluorescence techniques are the most powerful tools for assessing intact and subcellular pH,because of its high sensitivity,high spatial,temporal resolution and simple operation.pH probes for different cell regions have been reported.In this paper,three kinds of pH fluorescent probes were synthesized and their properties were studied.Chapter 1:This chapter presented molecular recognition and fluorescence probe,including the composition,fluorophore and recognition mechanism of the fluorescent probes.In addition,the research progress of pH fluorescent probe was described in detail.Chapter 2:We reported a colorimetric and fluorescent pH probe1-(4-methylphenyl)-3-(4-dimethylaminophenyl)acrylketone(probe1).Probe 1 exhibited strong pH-dependent behavior and responded linearly and rapidly to minor pH fluctuations within the range of 1.53-3.96.In addition,probe 1 displayed a notably large Stokes shift of 121 nm.Probe 1 possessed a highly selective response to H~+over other metal ions,amion acids and displayed good photostability and excellent reversibility.Furthermore,it can be applied to visualize extreme acidity in E.coli cells.Chapter 3:We developed a pyrene-based colorimetric and fluorescent pH probe 2-pyrenyl-1,8-naphthyridine(probe 2)with large Stokes shift(145nm).Probe 2 afforded a pK_a of 2.98 and responded linearly to minor pH changes within the range of 2.43 and 3.71.In addition,probe 2 could be used for detecting H~+with high sensitivity and selectivity,showing colorimetric and fluorometric dual-modal responses with short response time.Furthermore,probe 2 had good photostability,excellent reversibility and cell membrane permeability.Significantly,probe 2 could image acidic pH in A549 cells and visualized extreme acidity in E.coli cells.Chapter 4:We described a pyrene-based fluorescent probe 3-(2,6-dichloropyridine)-1-pyrenyl-2-propenone(probe 3)for the detection of pH.Probe 3 responded to pH changes with distinct signals in same system.Probe 3 showed a remarkable ratiometric change in the emission(blue shifted from 460 nm to 420 nm)spectra with addition of H~+.Upon the increasing of OH~-concentration,the fluorescence intensity at 463 nm decreased gradually.Probe 3 featured fluorescent responses for pH with rapid response time and high selectivity.In addition,probe 3 exhibited excellent cell permeability for the successful detection of pH in A549 cells.Moreover,we have further demonstrated that probe 3 could be used for imaging extreme acidity or extreme alkalinity in E.coli cells.