Synthesis And Application Of Two-Color Viscosity And Formaldehyde Fluorescent Probe

In the past decades,fluorescent probes have played an important role in biochemistry,material science,drug chemistry,medical diagnosis and cell biology.Molecular fluorescence probe technology has become a key analytical tool which is widely used in chemical and biomedical research of molecules,cells,and even organisms.Intracellular viscosity can reflect the transport of some chemicals and the transfer of chemical signals in cells because it affects the interaction between membrane molecules and the diffusion of some metabolites in living cells.In biological systems,changes in viscosity are associated with diseases and failures at cellular levels.Abnormal lysosomal and mitochondrial viscosities can lead to conditions such as diabetes,neurological diseases,and even cancer.Therefore,directed detection of intracellular viscosity is significant for both chemical and biomedical applications.In this paper,four kinds of viscosity fluorescence probes SY-L1,SY-L2,SY-M1,SY-M2 were designed and synthesized by using 2,3,3-trimethylindoleine,2,3,3-trimethylbenzoindoleine,indole-3-carboxaldehyde,1,3-propanesultone,dimethylaniline,and iodomethane as the main raw material.Through the comparison of spectral properties,such as the response to viscosity,the stability to pH and whether they were affected by solvent polarity,SY-L1 and SY-M2 were selected as dual color fluorescent rotor probes for imaging lysosomes and mitochondria in living cells.Fluorescence tests show that SY-L1 emits at around 550 nm and SY-M2 emits at around 660 nm.The emission peaks of the them are very small.The autophagy can be observed more clearly through the contrast of the two colors.Cell imaging results showed that SY-L1 and SY-M2 can be well mapped to lysosomes and mitochondria,respectively,their combination will become a powerful tool for two-color labeling,and has been successfully applied to mitochondrial autophagy sensing in living cells.It provides a good idea for developing an effective and versatile imaging strategy for mitochondria and lysosomes.Formaldehyde(FA)is the simplest aldehyde,it is a well-known carcinogenic and mutagenic contaminant.The normal level of intracellular FA plays an imp ortant role in the formation of cognitive ability.Excessive FA can lead to learning and memory disorders,allergic lung inflammation,asthma symptoms,cardiovascular diseases,cancer and other diseases.Therefore,it is very important to detect the conten t of FA in various environments,including living systems,food and cells.In this paper,using iron powder,zinc powder,ammonium chloride,titanium tetrachloride,benzophenone and 4-nitrobenzophenone as main raw materials,a FA fluorescence probe AIE-FA based on aggregation-induced luminescence(AIE)mechanism was designed and developed.It consists of a tetraphenylethylene(TPE)scaffold with two amino groups.TPE is a typical AIE fluorophore which does not emit in dilute solution but has very strong emission in the state of aggregation.The two amino groups not only act as reactive parts of FA,but also increase the water solubility.After condensation with FA,the probes were converted into Schiff bases,resulting in poor solubility and formation of aggregated products,and the polymerization product turns on the fluorescent signal to achieve the purpose of detecting FA.The in vitro results show that the AIE-FA probe has a rapid response,high selectivity and sensitivity to FA.In vivo studies show that AIE-FA can image both endogenous and exogenous FA in living cells.In addition,AIE-FA has also been used in real-time imaging of endogenous FA.These advantages may give our AIE-FA probe great potential for long-term tracking of FA concentrations under different conditions in the physiological system.