Construction And Application Of Fluorescent Probes Based On Hemicyanine Dyes

Fluorescent probes,which featured with the inherent superiorties including high sensitivity,designable and noninvasiveness,had recently wide application in analytical and biological chemistry.As an important part of traditional cyanine dyes,hemicyanine fluorescent dyes have been widely developed as fluorescent probes for the large Stokes shift,large molar extinction coefficient and adjustable structure.However,fluorescent probes based on hemicyanine dyes sometimes showed poor water solubility,low photostability,short emission wavelength and strong solvent effect,and could not be applied to the detection of biomolecular and cellular microenvironment and the targeting of subcellular level organelles.Based on this,four novel hemicyanine fluorescent dyes which could reduce the solvation effect have been designed and synthesized in this paper,and a new solution was proposed for the deficiency of hemicyanine dyes in the construction of fluorescent probes.The paper mainly carried out the following work:(1)The probes Pe Bt and PeBi with typical D-?-A system were synthesized by the reaction of 3-Perylenecarboxaldehyde containing a rigid large ?-conjugated molecular skeleton with N-methylbenzothiazole and N-methylbenzoindole,and were systematically studied its photophysical performance and imaging performance.The maximum emission wavelengths of probes PeBt and PeBi in aqueous solution were723 nm and 606 nm,respectively.The Stokes shift of probe Pe Bt reached 196 nm,which would help increase the SNR of biological imaging.In addition,due to the large ?-conjugated system,the two fluorescent probes had weak solvent effect.In living cell imaging experiments,the probes PeBt and PeBi showed low cytotoxicity and good cell permeability.Compared with commercial localizers,the probes PeBt and PeBi had excellent photostability.In addition,the probes PeBt and PeBi were targeted to lysosomes and mitochondria,respectively.The probe PeBt was successfully used to monitor the dynamic changes of lysosomes in the process of apoptosis.These results provide a significant platform for the construction of functionally mitochondria and lysosome-targetable fluorescent probes.(2)We designed and synthesized the mitochondria-targetable and viscosity-sensitive fluorescent probes PyQz and PeI.Based on TICT mechanism,the probes PyQz and PeI showed a weak fluorescence at a viscosity value of 1.00 cP,and the fluorescence intensity increased significantly at 600 nm and 737 nm in 95%glycerol solution,respectively.At the same time,the probes PyQz and PeI had excellent photophysical properties,including weak solvent effect,not being affected by physiological pH,large Stokes shift,excellent selectivity and anti-interference ability.Additionally,the probes PyQz and PeI have been successfully used to monitor the viscosity changes of mitochondria caused by the addition of ionophores(monensin).