Synthesis And Properties Of Near Infrared Fluorescent Probes For Detecting HClO,HNO And Hg²⁺

In recent years,near infrared fluorescent probes have gradually become a research hotspot in the field of fluorescent probes because of their advantages of small background interference,strong tissue permeability and less damage to tissues or cells.In the field of biology,hypochlorite?HOCl?is an important reactive oxygen species?ROS?,which plays a very important role in the immune system.Nitroxyl?HNO?has unique biological activity and pharmacological application.It can be used to treat alcoholism,alleviate ischemia-reperfusion injury and has potential to treat heart failure.Mercury ion(Hg²⁺),a heavy metal ion commonly found in industrial wastewater,can bind with mercaptan groups in enzymes and proteins in human body,causing various kidney and brain-related diseases,such as Minamata disease.In view of the advantages of near-infrared fluorescent probes in biological imaging and the important roles of HOCl,HNO and Hg²⁺in physiological processes,the development of near-infrared fluorescent probes for detecting HOCl,HNO and Hg²⁺in organisms has gradually become a research hotspot in recent years,and is also an indispensable technical means for further study of their biological characteristics and pharmacological potential.In this paper,four near infrared fluorescence probes LJ-1,LJ-2,LJ-3 and LJ-4for detecting HOCl,HNO and Hg²⁺were designed and synthesized based on three different near infrared fluorescence groups:benzopyran nitrile,hemicyanine dye and benzopyran-coumarin.The spectral properties,recognition mechanism and cell imaging of the four probes were studied.The structures of the four probes were confirmed by ¹HMR,¹³CNMR and HR-MS data.The two-photon,near infrared HOClfluorescence probe LJ-1 based on DCMhas the advantages of rapid response,high sensitivity,strong anti-interference ability and large stokes shift.It has been successfully applied to detect HOCl in MCF-7 cells by single-photon and two-photon imaging.The near infrared HNO fluorescence probe LJ-2 based on DCM has the advantages of fast response to HNO,specificity recognition,strong anti-interference ability and high sensitivity.LJ-2 probe has been successfully applied to detect HNO in HEPG-2 cells.The near infrared HNO fluorescence probe LJ-3 based on benzopyran-coumarin can respond rapidly to HNO in pure water system HEPES Buffer?10 mM,pH=7.4?.Dual-channel detection of endogenous and exogenous HNO in HEPG-2 cells has been achieved.Thenear infrared Hg²⁺fluorescence probe LJ-4 based onhemicyanine dye can identify Hg²⁺specifically and has strong anti-interference ability and high sensitivity.After the response,the color of the solution changed from blue to green,which could be recognized by naked eyes.It has been successfully applied to the detection of Hg²⁺in HEPG-2 cells.