| In recent years,fluorescent technology has been widely used in the fields of biology,medical science and medicine.As an ideal detection tool,fluorescent probe has the advantages of high sensitivity,strong operability,low cost,good selectivity,fast and accurate,and in-situ measurement.It has been widely concerned in Biomacromolecules detection,ion detection,cytology application,immunology application and so on.However,most of the current organic fluorescent probes have the effect of aggregation-caused quenching（ACQ）,and have poor water solubility,poor cell permeability and strong toxicity,which cannot be used in biological imaging and living tissue imaging.Therefore,it is of great significance to develop triphenylamine probes with good biocompatibility and aggregation-induced emission（AIE）properties.Triphenylamine is a fluorescent core with a propeller structure.In the structural unit of triphenylamine,because of the three benzene rings connected to the nitrogen atom have high activity,structural diversity,easy cutting and modification characteristics,a series of reactions can be performed to bond different Functional group,thereby obtaining a series of triphenylamine materials with specific function.In view of this,several highly selective and sensitive organic small molecule fluorescent probes are designed.And they are used to detect reactive oxygen species（ROS）.Study their mechanism and apply to biological imaging.The main research contents and results are as follows:1.A series of triphenylamine derivatives with one-,two-and three-substituted pyridine salt groups were obtained by suzuki-miyaura coupling reaction and Menshutkin reaction.And by changing the anions（I-,BF4-and PF6-）,a small library of fluorescent compounds was constructed.The effects of different anions and different number of substituents on optical properties and application were systematically studied.Among them,the anion BF4-is more beneficial to increase the emission wavelength to a longer range,and anion PF6-is more conducive to enhancing the fluorescence intensity.Through cell imaging experiments,it was found that with the increase of the number of positive charges,the imaging site was slowly transferred from mitochondria to the nucleus.For this result we can establish the relationship between chemical structure and specific organelle targeted staining.Due to the high degree of overlap between fluorescent probes and commercial dyes,they completely can be used as mitochondrial and nuclear imaging dyes.Subsequently,the response recognition of O2·-in vivo and in vitro was carried out.The results showed that the probes had the potential to monitor the endogenous O2·-fluctuation in cells.2.The triphenylamine compounds have poor water solubility,which affects their application.These compounds were encapsulated into commercial copolymer F127through self-assembly to prepare nanoparticles（NPs）with more biocompatibility and water-dispersibility.It was proved by SEM and TEM that spherical micelles with clear morphology were obtained,with an average diameter of 40-50 nm.The nanoparticles is very stable in the physiological pH range.Biological imaging of mammalian HeLa cells and plant Tobacco（Nicotiana tabacum L.cv.Bright Yellow 2）cells was completed.Fluorescent nanoparticles can easily through the cell membrane,but it is difficult to penetrate the cell wall.Therefore,An effective method is proposed to design and prepare polymer nanoparticles based on nanoparticle systems.3.With triphenylamine as the fluorescent core,the molecules TPAs-SCH3,TPAs-2SCH3,TPAs-3SCH3,and TPAs-SCH3-2CN were obtained by modifying triphenylamine.TPAs-SCH3-2CN is a D-π-A system and is a typical AIE molecule.It is the most specific and sensitive ClO-.In the presence of ClO-,there were significant changes in emission wavelength and fluorescence intensity.NMR and HRMS were used to investigate the oxidation mechanism.It was proved that there were two reaction sites,in which the vinyl and thioether groups were oxidized to formyl and sulfone groups.This kind of probe with dual reaction sites is of great significance for ROS sensing.In addition,the probe is used for cell imaging.When the endogenous ClO-level of the cell gradually increases,the intensity of green fluorescence at the lipid droplet becomes stronger,and the dual-channel monitoring strategy provides real-time observation of the endogenous ClO-.The probe also has good fluorescence performance in zebrafish tissues imaging and can be used for biological identification. |
