Synthesis And Bioimaging Applications Of Fluorescent Probes For Superoxide Anions And Carbon Monoxide Based On Naphthalimide

Superoxide anion(O₂^·-)is one of the most important reactive oxygen species（ROS）in biology.O₂^·-is widely involved in cell signaling,excess O₂^·-can cause damage to biofilms and tissues.O₂^·-is associated with inflammation,diabetes,malignant tumors,neurodegenerative diseases and other diseases.Carbon monoxide（CO）is the most abundant and widely distributed gaseous pollutant in the atmosphere.In addition,CO is also a gaseous signal molecule in organisms,which plays an important role in regulating many physiological and pathological changes,including respiratory system,blood circulatory system and nervous system.Therefore,it is of great significance to develop methods for detecting and tracking O₂^·-and CO in life systems.Fluorescent probes can be used for non-invasive in situ detection through real-time reaction with specific detectors.At the same time,according to the change of the color or intensity of the fluorescent probe itself,we can effectively analyze the detection quantitatively or qualitatively.Therefore,fluorescent probe has become a widely used research tool in the field of life science.At present,we have not established a system on the action mechanism of O₂^·-and CO in vivo.In order to fully study their role in the physiological or pathological process of life,a fluorescent probe for the detection of O₂^·-and CO was designed and synthesized using naphthalimide as a fluorescent group for tracking O₂^·-and CO in organisms or cells.In the first part,based on naphthalimide fluorophore,a lysosome-targeted O₂^·-two-photon probe Lyso-MHC was constructed by using trifluoromethanesulfonate as the O₂^·-recognition site and morpholine as the lysosome targeting group.The fluorescence of the probe itself is very weak,and the fluorescence is significantly enhanced after it reacts with O₂^·-.It is a kind of open fluorescence probe.The emission wavelength is 556 nm.In the presence of O₂^·-,trifluoromethanesulfonate leaves the reaction to form hydroxyl groups,and the naphthalimide fluorophore emits bright yellow light and can well target lysosomes.In biological imaging,it can sensitively identify exogenous and endogenous O₂^·-in cells and zebrafish.In addition,the excess O₂^·-produced in mouse pneumonia tissue can be detected in situ.In the second part,based on Tsuji-Trost reaction,a specific CO fluorescent probe ERCO targeted to endoplasmic reticulum was designed using allyl ether as CO reaction site,1,8-naphthalimide as fluorophore and methanesulfonamide as targeting group.After adding Pd Cl₂ and CORM-2,allyl ethers leave to form hydroxyl groups.The probe changes from blue light to yellow light,and the emission wavelength of the probe changes from 456 nm to 553 nm.The ratio probe can effectively reduce the background interference,and it is a kind of probe which is very beneficial to fluorescence imaging.The probe has the advantages of good photostability,strong selectivity and high signal-to-noise ratio.In the biological imaging experiment,the probe can well target the cellular endoplasmic reticulum and effectively image the endogenous and exogenous CO.