Application Of AIE Fluorescent Materials In Biosensing,cell Imaging And Photodynamic Therapy

"Aggregation-Induced Emission"?AIE?breaks through the bottleneck of traditional fluorescence aggregation quenching and realizes a revolution in fluorescent probe molecules.In the scientific research field,luminescent materials have been limited by the limitations of Aggregate Caused Quenching?ACQ?,and it is difficult to apply them on a large scale.This phenomenon of ACQ is very troublesome for researchers in the field of luminescence,because many luminescent materials are used in the solid state,such as mobile phone screens.However,AIE materials have solved this problem very well.It can be said that the discovery of AIE phenomenon provides a new research direction in the field of fluorescent materials.In recent years,chemical sensors,biosensors,bio-imaging and biomedical treatment have achieved remarkable results.At present,the basic skeleton of the common AIE type fluorescent molecule mainly includes tetrastyrene?TPE?,hexaphenylthiazole?HPS?and so on.Among the many fluorescent chromophores,triphenylamine is a common fluorescent core with a propeller structure.In the triphenylamine structural unit,since the three benzene rings attached to the nitrogen atom have high activity and easy modification characteristics.A series of triphenylamine derivative materials having a specific function can be obtained by performing a series of reactions at a suitable position on the benzene ring to bond different functional groups.However,triphenylamine,its derivatives and commercially available dyes have a number of disadvantages respectively.Firstly,triphenylamine and most of its derivatives have a large conjugated structure,which is prone to?-?stacking,which causes the fluorescence of the molecule to quench,It is a typical ACQ molecule.Secondly,the dyes currently used commercially are not only expensive but also mostly carcinogenic.Therefore,the development of triphenylamine-based fluorescent materials with AIE properties is of great significance.In view of this,the paper mainly synthesized a series of AIE-type fluorescent molecular probes with different properties using triphenylamine as a chromophore.In one aspect,some novel fluorescent probes are synthesized by modifying certain specific functional groups such as boric acid,dihydropyridine,and pyridinium salts,and are applied to the recognition of ATP,O₂^.-,and their cell imaging.On the other hand,the application of different donor-acceptance?D-A?electronic systems in photodynamic therapy was examined.This paper is mainly composed of the following three parts:1.As a cellular energy substance,ATP plays an extremely important role in cell and body health.Therefore,the detection of ATP is particularly important.In this experiment,an ATP recognition probe was designed based on the specific binding of boric acid to o-diol and the positive and negative charge attraction of pyridine cation and phosphoric acid.Due to the multi-locus modification of triphenylamine,a multi-site binding ATP recognition probe was developed.The experimental results show that the recognition ability of ATP is sharply enhanced with the increase of binding sites,and the change of TPA-PPA-3 fluorescence intensity reaches 33 times.And through cell imaging experiments,it is found that with the increase of the number of positive charges,the imaging site is slowly transferred from the cytoplasm to the nucleus.Because TPA-PPA-3 has a very high overlap with the commercially available nuclear stain?DAPI?,it can be completely used as a kind.Therefore,TPA-PPA-3 can be used completely as o nuclear develooper to aviod the use of strong carcinogenic DAPI.2.Using triphenylamine as the core,a series of fluorescent compound libraries from blue light to red light emission were synthesized by modifying triphenylamine?TPA?.Among all the fluorescent materials,TPA-DHP-1 and TPA-PPA-1 showed excellent fluorescence response in the presence of external pressure,and the mechanism of piezochromism was fully discussed.In addition,due to the conformational transition after oxidation of TPA-DHP-1,2,3 series compounds,TPA-PPA-1,2,3 series compounds were able to perform simple proton separation and nucleophilic reaction in the presence of O₂^.-,and developed two class-shift fluorescent sensor.Both types of probes exhibit three distinct features:?1?due to dramatic changes in wavelength,increased fluorescence intensity,and irreversible chemical conversion,which can reduce unwanted background fluorescence interference.?2?Rapid,sensitive and dynamic monitoring of O₂^.-in different cells from living cells and in vitro.?3?The dual-channel monitoring strategy not only provides real-time observation of O₂^.-in the mitochondria of cells,but also images both the nucleus and mitochondria.Therefore,this study can provide a simpler,more accurate and feasible method for detecting biologically active small molecules in living cells.3.As a good electron donor,triphenylamine can be used as a donor unit to systematically study the D-A and A-D-A red light small molecule materials.However,such literature is not much and not deep enough.Based on this,we used TPA as an electron donating group,and systematically studied the construction of different D-A and A-D-A small molecules through the combination of different receptor units by unilateral and bilateral modification,respectively.Regulates the electron cloud density of the molecule,enhances the intersystem crossing?ISC?process of the compound,reduces the band gap,and the effect of heavy atoms on photodynamic therapy?PDT?.The ability to generate singlet oxygen?¹O₂?was verified by singlet oxygen probes?SOSG?,and it was found that A-D-A molecules containing heavy atoms have superior¹O₂ production ability.It is also found that the heavy-atomic ADA molecule TPA-18has a very good PDT ability and can have a good antibacterial effect against both Gram-negative and Gram-positive bacteria,and can target the mitochondria of cells to destroy cancers cells.This design idea provides theoretical guidance for molecular design in PDT.