Synthesis And Properties Of Fluorescent Probes For Detecting SO₂,Cys,HClO And ONOO^-

SO2,Cys,HClO and ONOO-in organisms can fluctuate within the normal concentration range,and abnormal levels may lead to certain diseases,therefore,the development of tools that can sensitively detect these active molecules will help to conduct in-depth research on the occurrence and mechanism of certain diseases.Fluorescent probes have the advantages of simple synthesis,no damage to tissues,in situ detection,and high sensitivity.Therefore,the development of new fluorescent probes to detect the changes of SO2,Cys,HClO and ONOO-in vivo has important application potential.This paper summarizes the research progress of SO2,Cys,HClO and ONOOfluorescent probes,based on fluorophores such as coumarin and rhodamine and different recognition sites,four fluorescent probes were constructed respectively.The structure of the target probe was confirmed by 1H NMR,13C NMR and HR-MS,Its in vitro properties were studied by UV spectroscopy and fluorescence spectroscopy,the details are as follows:(1)Based on the addition reaction of SO2 to the double bond,the near-infrared ratiometric fluorescent probe Y-1 was synthesized with coumarin as the fluorophore.The single probe emits red fluorescence at the wavelength of 650 nm,when the probe responds to SO2,the fluorescence at the wavelength of 650 nm is weakened,and a new yellow-green fluorescence appears at the wavelength of 540 nm.The solution changed from purple to colorless before and after recognition by the probe,which has the ability of naked eye recognition.Competitive experiments show that the probe can specifically recognize SO2 without interference from other active molecules.The kinetic test found that the response of the probe to SO2 reached a response plateau after half an hour.The detection limit of the probe is 665.38 nM,which is applicable in the pH range of 4-12,and has potential for application in physiological environment.(2)A fluorescent probe Y-2 for simultaneous detection of Cys and HClO was designed and synthesized based on the "AND" logic gate.After adding Cys to the probe solution,it showed weak fluorescence at 570 nm,when HClO was added,the fluorescence intensity at 570 nm increased significantly.Selectivity and competition experiments show that the probe can specifically recognize Cys and HClO without interference from other active molecules.The detection limit of the probe was 325 nM.(3)An example of ONOO-fluorescent probe Y-3 was synthesized based on twosite response.Kinetic assay,the probe can instantaneously reach a response plateau after ONOO-addition.Selection and competition experiments show that the probe can specifically recognize ONOO-and has a good recognition effect in the pH range of 28.(4)The Cys fluorescent probe NCS-1 was constructed by a simple two-step reaction.In 10 mM PBS buffer solution,after the probe recognizes Cys,it emits strong fluorescence at a wavelength of 572 nm,and reaches the response plateau in 15 min.The probe has good specificity and anti-interference ability,can distinguish Cys and GSH well,and the detection limit is as low as 84.7 nM.The probe has a good recognition effect on Cys in the pH range of 6-11.