Synthesis And Properties Of Fe²⁺ And ONOO^- Fluorescent Probes Based On Dicyanomethylene–Benzopyran

Iron?Fe?is a rich metal element in human body,which plays an important role in biology and pathology.Iron mainly exists in the form of ferrous iron(Fe²⁺)and ferri iron(Fe³⁺)in vivo,because Fe³⁺is easily reduced to Fe²⁺and has poor solublity under alkaline physiological conditions.On the other hand,Fe²⁺catalyzes Fenton reaction to generate free radicals,which may cause a series of diseases.Therefore,it is very important to design a fast and accurate probe to detect ferrous iron in vivo.As one of the reactive nitrogen species?RNS?molecules in vivo,peroxynitrite?ONOO^-?is generated by the reaction of superoxide radical(O₂^?-)and nitric oxide?NO?.As a strong biological oxidant,ONOO^-has instability and high reactivity,and is a signal transduction molecule in some biological circulation pathways.However,such conductive molecules may also cause irreversible damage to some biological target cells,such as cancer,inflammation and cardiovascular diseases.Therefore,designing a suitable probe is critical for ONOO^-detection.?1?Designing a synthetic probe K1 to detect Fe²⁺.Fluorescence probe K1 was synthesized by introducing N-oxide into dicyanomethylene-benzopyran to explore the possible mechanism of reaction between probe K1 and Fe²⁺,and characterize its structure.In this work,through the study of optical physical properties,it was found that the probe had almost no fluorescence in PBS/DMF=1:9?0.01 M,pH 7.4?buffer solution.After adding Fe²⁺,N-oxide was reduced and fluorescence was restored,and the maximum emission was obtained at 685 nm.The probe has the characteristics of good selectivity and high sensitivity(2.96×10^-6?M),and is applied to Fe²⁺fluorescence imaging in C.elegans and living cells.?2?Designing a synthetic probe K2 to detect ONOO^-.Fluorescence probe K2was synthesized with dicyanomethylene-benzopyran and coumarin to explore the possible mechanism of the reaction between probe K2 and ONOO^-,and characterize its structure.In HEPES/DMF=1:9?0.01 M,pH 7.4?buffer system under light physical properties test,when adding saturated equivalent ONOO^-,the probe fluorescence spectral blue shift obviously,and can realize the recognition of ONOO^-specificity,detection limit as low as 6×10^-7?M.More importantly,the probe was applied to ONOO^-fluorescence imaging in living cells.