NBD-derived Fluorescent Probes For Sensing Of Metal Ions Based On PET Mechanism And Bioimaging Study

Chapter 1:Mainly introduces the generation of fluorescence,recognition mechanism of fluorescence probes,and summarizes the development status of NBD fluorescent probes.Chapter 2:A Schiff base fluorescent probe AH was synthesized with4-chloro-7-nitro-2,1,3-benoxadiazole（NBD-Cl）as raw material to achieve detection of Cu²⁺with high selectivity.In aqueous CH₃CN solution（CH₃CN/H₂O,1:1,v/v,p H=7.4）,AH was effectively complexed with Cu²⁺at a chemical ratio of 1:1,resulting in a nearly25-fold fluorescence enhancement at 540 nm and a significant change in color from orange to gray-blue.The probe AH showed excellent sensitivity to Cu²⁺,and the detection limit is as low as 42.2 n M.The enhanced fluorescence may be due to the inhibition of the photoinduced electron transfer（PET）process and the combination of chelate fluorescence enhancement（CHEF）effect after AH and Cu²⁺ions were coordinated through the lone electron pair on aniline.Fluorescence imaging showed that AH probe could be used for the detection of Cu²⁺in Hela cells,locust martensii canals and zebrafish.Chapter 3:A novel fluorescent probe HENB was designed and synthesized for selective detection of Fe³⁺.In CH₃CH₂OH/H₂O（1:1,v/v,25 m M HEPES buffer solution,p H=7.2）,the fluorescence of probe HENB was significantly enhanced after complexation with Fe³⁺,due to the inhibition of the PET process in probe HENB during the formation of the complex with Fe³⁺.The intense green fluorescence can be easily seen by the naked eye under ultraviolet lamp.In addition,fluorescence imaging studies have shown that HENB can monitor endogenous and exogenous Fe³⁺in human liver cancer cells（SMMC-7721）and zebrafish.Chapter 4:A new type of fluorescent probe HPNB was synthesized for selective detection of toxic Hg²⁺.In a neutral solution,the sensor HPNB is complexed with Hg²⁺at a 1:1 stoichiometric ratio,blocking the photoinduced electron transfer（PET）process and causing a significant enhancement of emission intensity.HPNB shows excellent selectivity and sensitivity to Hg²⁺,and the detection limit is 6.43×10^-9 M.In addition,HPNB can be further used to monitor Hg²⁺levels in Hela cells.