Design And Biological Application Of PH And HClO Fluorescent Probes

The pH value of organisms can affect cell functions and regulate a variety of physiological and pathological processes.Abnormal intracellular pH leads to intracellular enzyme activity decrease or deactivation,which will cause various diseases such as inflammation and tumors.HClO is one of the important reactive oxygen species(ROS)with strong oxidation and weak acidity.It plays an important role in the immune system.However,excessive HClO would affect the structure and stability of proteins,inhibite the activity of various enzymes,and affect the normal activities of organisms to a large extent.Therefore,the detection of intracellular pH and HClO concentration is of great importance to the stability of biological ecosystem.As a new analytical and detection technology,fluorescence probe requires relatively simple instrument,has the advantanges of high sensitivity,real-time monitoring,non-invasive,high spatial,and temporal resolution in detecting biological samples.Moreover,fluorescent probe has realized the visual imaging detection of biological samples,which is an ideal method to detect pH and HClO.Coumarin,rhodamine and Aza-BODIPY were selected as fluorophores to construct fluorescence probes respectively for detecting pH and HClO in vivo.The specific contents are as follows:(1)Based on the mechanism of rhodamine switch loop reaction,a novel pH fluorescence probe R-1 was designed and synthesized.The probe R-1had dual channel signals of rhodamine and dansulfoyl fluoresce,showed different fluorescence signals in different pH environments.In the biological application experiment,the probe R-1 not only rapidly aggregated lysosomes in cells and detected the changes of intracellular lysosomal pH value in the process of starvation induced autophagy,but also visualized the process of starvation induced autophagy in living cells.What’s more,the probe R-1 distinguished neutral lysosomes from acid lysosomes during autophagy.(2)A novel HClO fluorescence probe C-1 was designed by Coumarin.Due to the PET effect,the fluorescence signal increased 140 times after recognition and the color of the probe solution changed from colorless to green.The fluorescence intensity had a good linear relationship with HClO concentration in the range of 0-45 μM,the detection limit was 33.6 nm.In addition,the probe C-1 also had the advantages of low cytotoxicity.More importantly,the probe had been successfully applied to detect HClO changes in He La cells and zebrafish.(3)The probe B-1 included Aza-BODIPY fluorophore and aldoxime group recognition group.The aldehyde oxime group of the probe changes to nitrile group once the probe B-1 was oxidized by HClO,then the fluorescence of the probe B-1 was quenched.The probe had excellent properties such as high selectivity,low cytotoxicity and low detection limit(2.33 nm).Whether in acidic,neutral or alkaline environment,the probe can specifically recognize hypochlorous.The probe B-1 was less affected by pH.In addition,the detection results are less affected by the organism itself because the probe B-1 had an emission wavelength longer than 700 nm.In the biological application experiment,the probe B-1 had the ability to target mitochondria and had been successfully used to detect HClO in cells and in mouse model of arthriti.