Synthesis And Selective Recognition Of Fluoroborodipyrrole Reactive Fluorescent Probes

Fluorine dipyrrole?BODIPY?derivatives are a kind of good photosensitizing dyes.These dyes are widely used as optical chemical sensors,fluorescent biolabeling reagents,lighting materials and photodynamic therapy reagents,and so on.In this paper,based on the excellent fluorescence structure of fluoroboron dipyrrole,a near-infrared fluorescent probe that could achieve selective recognition for bio-thiol was designed and synthesized.Then,the lysosomal localization group was also modified at the 8-position of BODIPY,which could not only achieve its lysosomal localization,but also specifically recognize hypochlorous acid.At the same time,BODIPY with aggregation-induced fluorescence properties was synthesized and its properties was tested.1.A near-infrared turn-on two-photon fluorescent probe ST-BODIPY for glutathione-specific detection was designed and synthesized by attaching triphenylamine to BODIPY skeleton through the Knoevenagel condensation to prolong the maximum emission wavelength to the NIR region.And 2,4-dinitrobenzenesulfonyl group?DNBS?,as the fluorescence quencher and thiol recognition moiety,was modified in 8-position of BODIPY.In the presence of GSH,the probe afforded an“off-on”signal response with a significant NIR fluorescence enhancement centered at 719 nm accompanying by quantum yield increased to0.44 and its limit of detection for GSH was as low as 25.46 nM.Under the Ti:sapphire pulsed laser's 800 nm irradiation,ST-BODIPY toward GSH generated an“off-on”signal response with a significant enhancement of fluorescence emission at 719 nm after treatment with GSH.Besides,the 2PA cross section value??₂?was calculated to be 410 GM,suggesting that it could not only function well as an excellent two-photon fluorescent probe for the detection of intracellular GSH,but also be applied for two-photon imaging with high sensitivity in living cells.Moreover,ST-BODIPY probe has been successfully employed for monitoring exogenous and endogenous GSH in MCF-7 cells.2.For highly sensitive and selective detection of ClO^-over other reactive oxygen species?ROS?and anions,a fluorescent probe MN-BODIPY by introducing a morpholine group into the 8-position of BODIPY which could be used for targeting lysosome and improving water solubility was designed and synthesized.As a result of the C=N isomerization mechanism at 2-position of BODIPY,the probe alone displayed extremely weak fluorescence.However,in the presence of ClO^-,the probe exhibited a dramatic enhancement of fluorescence intensity by a 29-fold increase at 530 nm accompanying with quantum yield change from 0.03 to 0.25 and a new absorption band centered at 505 nm appeared which presented a 16 nm blue-shift as compared with the absorbance of MN-BODIPY.Accordingly,the probe displayed fast response for ClO^-within 30 s.The limit of detection?LOD?for ClO^-was calculated as 16.5 nM from the titration experiments,which is lower than most previously reported CiO^--selective probes.What's more,MN-BODIPY has been successfully employed for monitoring exogenous and endogenous hypochlorous in MCF-7 cells with satisfying results,perhaps it was feasible for detecting abnormal contents of hypochlorous in a biological system and accomplish the goal of maintaining normal human activities.3.A novel red aggregation-induced emission?AIE?Dual-channel chromophore named Coumarin-BODIPY was designed,consisting of D-A system where BODIPY core as electron acceptor and Coumarin directly linked in 8 position of BODIPY as electron donor.The probe emit red fluorescence in the solid state with a maximum emission wavelength at 616 nm.There was no fluorescence in pure DMSO and with less water fractions.However,the intensities centered at 626 nm increased obviously with much higher water fractions and the fluorescence intensities in 95%water fraction DMSO/H₂O mixtures reached the maximum and its quantum yield was 0.12,demonstrating typical aggregation induced red emission.Crystal structure analysis attested that large dihedral angle and Intermolecular interaction restricted intramolecular rotation which was the mechanism of AIE characters.DLS experimental results also demonstrated the formation of aggregates.Besides,average diameter of CT-BODIPY loaded Si-NPs was less than 40 nm,which further displayed its valuable applications in biological system.Importantly,Coumarin-BODIPY can achieve fast detection for bovine serum albumin?BSA?based on the AIE.The red fluorescence intensity in the test system at 626 nm was increased by 8-fold when the concentration of BSA increased from 0 to 20?M.Furthermore,The pure dye was applied in Dual-channel cell imaging and showed a good uptake by MCF-7 cells which suggested it could be promising in biosensor applications.