Preparation Of Benzothiazole And Phenothiazine Heterocyclic Amphiphilic AIE Fluorescent Materials And Their Application In Bioimaging

Aggregation Induced Emission(AIE)fluorescent materials are a type of organic materials that can't emit fluorescence in the dispersed state,but can emit strong fluorescence in the aggregated state.The emergence of AIE fluorescent materials fills the application gap of traditional fluorescent materials baceuse of aggregation caused quench(ACQ).Although AIE fluorescent materials still have many unsolved problems,their unique aggregated luminescence property continue to arouse researchers'interest.In this thesis,there polymerizable AIE fluorescent monomers were designed and synthesized using tetraphenylethylene(TPE),benzothiadiazole(BTA)and phenothiazine derivatives as the basic structural units.Corresponding amphiphilic AIE fluorescent polymer was prepared by RAFT polymerization of the fluorescent monomer and poly(ethylene glycol)methacrylate(PEGMA),which solved the problem that the monomer was insoluble in water.Its unique properties and application prospects in the field of bioimaging were studied.The specific research contents are as follows.(1)pH sensitive AIE fluorescent monomer TPBMA was synthesized based on TPE and BTA derivatives.Its maximum emission wavelengths are 506 nm and 579 nm in neutral and acidic media,respectively,and can be repeatedly changed by HCl/NH₃fumigation.The amphiphilic fluorescent polymer PEG-TB was prepared by RAFT polymerization of TPBMA and PEGMA,and its molecular weight(Mw)and polydispersity index(PDI)were about 21200 g/mol and 1.30,respectively.PEG-TB can self-assemble into fluorescent organic nanoparticles(FONs)with diameters of about100-150 nm in aqueous solution.In addition,PEG-TB has the advantages of good water solubility,biocompatibility,endocytosis and low cytotoxicity.(2)AIE fluorescent monomer TTPA with electronic A-D structure was synthesized based on TPB and BTA derivatives,and its maximum emission wavelength was 524 nm.Because of the ICT effect,TTPA can still emit fluorescence in THF solution.The energy level difference?E_ST between the HOMO and LUMO of TPB and TTPA is 3.63 e V and2.81 e V,respectively.The fluorescent polymer PEG-PA was successfully prepared by RAFT polymerization of TTPA and PEGMA.Due to the amphiphilic,PEG-PA can self-assemble into FONs with a diameter of about 150-200 nm in aqueous solution.PEG-PA also has the advantages of good water solubility,low cytotoxicity,good biocompatibility,and easy cellular absorption.(3)AIE red fluorescent monomer BDPPA was prepared based on TPB and phenothiazine derivatives with maximum emission wavelength of 592 nm,and a shoulder peak at 629 nm.BDPPA can emit strong red fluorescence in THF as in aqueous water.The amphiphilic fluorescent polymer PEG-BD was successfully synthesized by RAFT polymerization of BDPPA and PEGMA.PEG-BD can self-assemble into FONs with a diameter of about 150 nm in aqueous solution.PEG-BD has the advantages of AIE,TICT,red emission,good water solubility,low cytotoxicity,good biocompatibility,good dispersibility,and easy endocytosis.