Synthesis And Properties Of Biological Thiol Fluorescent Probes Based On Naphthalimide Or Coumarin Derivatives

In recent years,fluorescent probes draw much attention by scholars,due to many advantages such as good selectivity,high sensitivity convenient and so on.However,the further application of fluorescent probes are subject to some limitations such as complex molecular structure,poor water solubility,lack of specificity and poor membrane permeability.Therefore,the design and systhesis of fluorescent probes with simple molecular structure,water solubility,high sensitivity,good selectivity and well membrane permeability are the main problem to solve at the present stage.Cysteine(Cys),homocysteine(Hcy)and reduced glutathione(GSH)are the main small molecular biological thiols in the organism.A series of physiological activities of the normal biological,all rely on these three amino acids to maintain.These three kinds of amino acids content can cause a series of physiological diseases,affecting people's normal life activities.For example,liver damage,muscle atrophy,Alzheimer's disease,cardiovascular disease,etc.Therefore,it is of great importance to find an effective and rapid method to detect small molecular biological thiols under physiological conditions.Coumarin is a kind of lactone compounds,which widely exists in nature.If the different position of coumarin ring is replaced,it can get a different range of fluorescence emission and absorption wavelength.And then we will be able to synthesize the coumarin derivatives that have a strong and different colors of fluorescence.As a traditional fluorescent dye,naphthalimide is widely studied in recent years because of its good thermal stability,easy to modify and so on.Based on the features of naphthalimide and coumarin,in this paper,we have designed and synthesized four fluorescent probes:3-(benzo[d]thiazol-2-yl)-2-oxo-2H-chromen-7-yl 2-chloroacetate(BTCA),2-Pyridyl-2,3-dihydro-1,3-dioxo-1H-benz[de]isoquinolin-6-yl-2-propenoate(NAPD),(E)-2-((2-(2-(2-hydroxyethyl)-1,3-dioxo-2,3-dihydro-1H-benz o[de]isoquinolin-6-yl)hydrazono)methyl)phenylacrylate(HIPA),Glyoxal(N-hydroxyet hyl-1,8-dicarboximide-4-naphthyl)monohydrazone(NAD)and studied fluorescence properties through a series of analysis and testing means.1.Coumarin-based fluorescent probe 1 was designed and synthesized by 2-amino thiophenol and 2,4-dihydroxy benzaldehyde.The experimental results show that probe BTCA can be used for the detection of Cys and Hcy and the obvious color change of solution can be observed by the naked eye.The fluorescence intensity of the probe BTCA increased with the increase of the concentration of Cys.At the same time,the cell imaging experiments also show that the fluorescent probe BTCA can be used as a cysteine and homocysteine fluorescence probe in the cells.2.Naphthalimide-based fluorescent probe NAPD was designed and synthesized by 4-bromo-1,8-naphthalimide and 2-aminopyridine.The experimental results show that probe NAPD can be used for "on-off" probe in detection of Cys and Fe3+with high selectivity and sensitivity.Cys can make the fluorescence of the probe NAPD enhanced,while with the addition of Fe3+,the fluorescence intensity of the system decrease gradually through coordination interaction.At the same time,the cell imaging experiments also show that the fluorescent probe NAPD can be used as a cysteine fluorescence probe in the cells.3.Naphthalimide-based fluorescent probe HIPA was designed and synthesized by 4-bromo-1,8-naphthalimide and 2-formylphenyl acrylate.The experimental results show that probe HIPA can be used for the detection of Cys with high selectivity and sensitivity.The fluorescence intensity of the probe HIPA decreased with the increase of the concentration of Cys.The probe further could be applied to detect Cys in Hela cells via intracellular fluorescent imaging.4.Naphthalimide-based fluorescent probe NAD was designed and synthesized by 4-bromo-1,8-naphthalimide and glyoxal.The experimental results show that probe NAD can be used for the detection of Cys with high selectivity and sensitivity.The fluorescence intensity of the probe NAD increased with the increase of the concentration of Cys.The probe further could be applied to detect Cys in Hela cells via intracellular fluorescent imaging.