Construction And Application Of Fluorescent Probe For Specific Recognition Of H₂S And SO₂

In nature,creatures and their surrounding environment always have a certain mutual relationship and interweaving effects.For an organic life,nutrition and energy need to be obtained from the outside world,and the material energy exchange will also be carried out in the internal environment.Hydrogen sulfide（H₂S）and sulfur dioxide（Sulfur dioxide,SO₂）are important small molecular substances that exist in the organism,and they also exist as gases in the surrounding environment.When the concentration of H₂S and SO₂in the body is excessive,it will cause pulmonary edema,diabetes,high blood pressure,cardiovascular and cerebrovascular diseases.Among all kinds of methods for analyzing and detecting small molecular substances,fluorescent imaging probes has the characteristics of non-invasive,intuitive,and fast in acquisition speed,and it can visualize the anatomy of living cells,which has become one of the advanced techniques of chemical biology research.This paper uses fluorescence imaging technology to detect H₂S and SO₂specifically,and it has been well applied in biological imaging.The research works are as follows:1.Designed and synthesized a benzene-conjugated coumarin fluorescent probe（P1）linked to 2,4-dinitrophenyl ether via an oxygen atom to detect H₂S specifically,and explored its application in biological imaging.We found that P1 has good light stability and chemical stability,and P1 has the ability to detect H₂S stably.In addition,compared with other dinitrophenyl ether probes of the same type,P1 has fast response speed,low detection limit and low toxicity.Furthermore,P1 can respond to endogenous and exogenous H₂S specifically,resulting in clear images in Hela cells.2.On the basis of the above-mentioned P1,we have optimized the structure of the probe,and studied the ratio-based fluorescence detection performance of bisquinoline-coupled fluorescent probe P2 to detect sulfur dioxide.Based on the previous system,we conjugated two quinolines to achieve a 100%water-soluble sulfur dioxide fluorescent probe.The probe shows a large Stokes shift（170 nm）in the spectrum test.In addition,it can respond to SO₂（LOD=0.29μM）within 1.5 min selectivity and sensitivity.In fluorescence colocalization experiments,P2 can be clearly imaged in living cell mitochondria and in mice.3.Based on the previous work,we developed and designed a fluorescent probe P3.P3 connects benzothiazole and quinoline through a double bond to extend the conjugated system,thereby increasing the emission wavelength and reaction speed.After a series of optical tests,the results showed that after the reaction with SO₂,the fluorescence emission peak increased continuously and a clear blue shift appeared.Compared with the previous work,it can produce obvious fluorescence enhancement after rapid response to SO₂ within 20 s.The lower detection limit and toxicity of P3 in response to SO₂laid the foundation for the successful application of P3 in endogenous and exogenous imaging.P3 can accumulate in the mitochondria of Hela cells for the detection of SO₂effectively.In addition,after P3 reacted with the SO₂donor,a significant change in fluorescence color can be seen in the cuvette,and the change in SO₂concentration can be observed under the naked eye.