Synthesis And Application Study Of Novel Organic Small Molecule Fluorescent Probes

Hydrogen peroxide(H2O2)and nitroreductase(NTR)are related to many physiological and pathological processes of biological systems.It is difficult to realize their real-time monitoring in organisms due to their distribution characteristics.Fluorescent probes have become one of the effective methods for detecting H2O2 and NTR for their advantages of fast response,high sensitivity,good selectivity,good biocompatibility,and real-time in-situ imaging.In this paper,four small molecule fluorescent probes were designed and synthesized,which are the probes HDP-1,HDP-2 and HDP-3 for detecting H2O2 and NFP-1 for detecting NTR.The application effects of the above probes were evaluated by in vitro experiments and cell experiments.The main research contents of this article are as follows:1.Using quaternary polycyclic quinoxaline compounds FL-01 and FL-02 as fluorescent groups and phenylborate as specific recognition groups,two novel fluorescence-enhanced H2O2 probes HDP-1 and HDP-2 based on ICT mechanism were designed and synthesized successfully.By comparing the optical properties(fluorescence spectrum,fluorescence quantum yield)of the two probes,probe HDP-2 with better fluorescence performance was selected to further explore its in vitro response and cell imaging ability.Probe HDP-2 had a low detection limit(46 n M)and can be used to detect low concentration H2O2 with high sensitivity.In addition,probe HDP-2 had good stability,low cytotoxicity,and had been successfully applied to the fluorescence imaging of exogenous and endogenous H2O2 in living cells.2.Using benzo indole compound EMC as probe skeleton and aryl boric acid ester group as specific recognition group,the ratiometric fluorescent probe HDP-3 based on ICT mechanism to detect H2O2 was synthesized.After the response to H2O2,probe HDP-3 was converted into the hydroxyl compound EMC-OH,which caused the intramolecular ICT effect changed.All changes resulted in the blue shift of the emission wavelength.The probe was highly selective for H2O2,with a fast response time of 30 min and a detection limit of 67 n M.In addition,probe HDP-3 also had no significant cytotoxicity to normal cells,and successfully achieved the ratiometric imaging of endogenous and exogenous H2O2 in living He La cells.1.In order to detect the level of NTR in living cells under hypoxia,a novel fluorescent probe NFP-1 was designed and synthesized.EMC was also used as the probe skeleton and aromatic nitro was connected as the specific binding site of NTR.In the presence of nicotinamide adenine dinucleotide(NADH)as the electron donor,probe NFP-1 could react with NTR specifically and showed significant fluorescence enhancement.Probe NFP-1 high selectivity,low cytotoxicity and fast response with NTR for 25 minutes.The detection limit was as low as 17 ng/m L.Cell imaging experiments proved that the probe NFP-1 can specifically detect the NTR induced by hypoxia in living cells.