Construction Of Small Molecule Probes Based On BODIPY Groups And Their Applications In The Detection Of Redox Compounds

The redox balance is of great significance to the normal physiological processes,and the abnormal content of redox molecules is closely related to many diseases.Therefore,there is an urgent need to develop techniques for real-time in situ detection of redox molecules in cells and vivo.Compared with the traditional detection methods,the organic small molecule probe has the advantages of high spatial and temporal resolution,high sensitivity,which can realize nondestructive and real-time imaging detection of cells and substances in vivo,and has been widely used in the biomedical field.However,there is still room for improvement in the imaging depth and selectivity of existing probes,and the development of molecular probes with stronger tissue penetration depth is a great challenge.In this paper,small molecule photoacoustic probe AZB-1,AZB-2 and small molecule fluorescent probe B-1,B-2 were designed and synthesized by introducing electron-absorbing group to BODIPY dye to recognize ONOO^-,HSO₃^-and S^2-,respectively.The photoacoustic and fluorescence imaging of these three redox small molecule compounds has been successfully achieved in vivo and in living cells.The specific work is as follows:(1)Synthesis of photoacoustic probe AZB-1 to detection and imaging of ONOO^-in vivoIn view of the shortcomings of existing fluorescent probes in detecting ONOO-,which are vulnerable to interference from other oxidizing substances and weak tissue penetration,we designed and synthesized two kinds of photoacoustic probes,AZB-1 and AZB-2,based on Aza-BODIPYgroup.The experimental results show that by introducing the conjugated???electron-absorbing groups into the 2 position of the Aza-BODIPPY chromophore,the radiation transition pathway of these compounds can be effectively blocked and the non-radiation transition of the molecule excited state can be improved.The excited state energy can be released by the probe in the form of heating to generate a strong photoacoustic signal.The results showed that the maximum absorption wavelength of probe AZB-1 was at 660 nm.As an"on-off"photoacoustic probe,AZB-1 had a good sensitivity to ONOO^-,and the photoacoustic signal can be quenched by reacting with ONOO^-.In addition,the probe was successfully used to detect and image ONOO^-in mice with rheumatoid arthritis model.(2)Synthesis of fluorescent probe B-1?B-2 and detection and imaging of HSO₃^-and S^2-The ratio fluorescent probe can effectively reduce the experimental error caused by the detection environment.We designed and synthesized two"ratio type"fluorescent probes B-1 and B-2 based on BODIPY chromophore by introducing 3-ethylbenzothiazole and 1-ethyl-3,3-dimethyl indolonium groups at the 2 position of the chromophore.The experiments showed that B-1 probe had good selectivity and sensitivity to HSO₃^-,it had a ratiometric response to HSO₃^-.When it reacted with HSO₃^-,the fluorescence value of the probe at 586 nm decreased,and the fluorescence value at 520 nm increased.There was a good linear relationship between the fluorescence ratio at two wavelengths and the added HSO₃^-concentration.B-2 probe had good selectivity and sensitivity to S^2-.When it reacted with S^2-,its fluorescence value decreased at 592 nm and increased at 520 nm.In addition,the detection and fluorescence imaging of HSO₃^-and S^2-were realized in MCF-7 cells using probes B-1 and B-2,respectively,which proved that these two fluorescent probes can provide an effective platform for the detection of reducing compounds in cells.