Preparation Of The Fluorescent Probes Based On Triphenylamine Electron Donor And Their Applications

Triphenylamine exhibits nonplanar molecular configuration with space distortion.It is an electron donor,which can lead to the red shift of emission spectra of organic fluorescent compounds up to the near-infrared range.This can expand the applications of organic fluorescent probes.Meantime,fluorophores containing triphenylamine usually exhibit aggregation-induced emission,which can show strong fluorescence in poor solvent.In recent years,food safety has been widely concerned by the society,especially the deterioration and corruption of food might lead to health issues.In living organism,the concentrations of biomarkers are abnormally in a higher level for many diseases.Effective detection of these biomarkers is very helpful for evaluating the development of diseases.As a non-invasine imaging method,fluorescence imaging is featured with ease of operation,fast,in-situ function and so on.Taking into account of the advantages of triphenylamine group,and to further expand the application field of fluorescence probe based on triphenylamine group,in this paper,triphenylamine has been chosen as the electron donor group,and three kinds of flouresent probes has been prepared by coupling it with different electron acceptors,which have been utilized in the field of food saftety and for detecting several biomarkers in organism respectively through the fluorescence detection.The main contents of this study are as follows:?1?A fluorescent probe for measuring the viscosity of beverages has been designed and synthesized.The near-infrared fluorescent probe?TPAEQ?with D-A structure has been prepared by using the triphenylamine as the electron donor?D?and tetranitrile-anthracene as the electron acceptor?A?.In the solution environment with enhanced viscosity,the excitation energy is dissipated through the radiative transition pathway,which leads to the enhanced fluorescence.The probe's response mechanism towards viscosity has been discussed,the specificity towards viscosity detection has been verified,and the spectroscopic performance in different polar solvents has been verified.The probe TPAEQ shows good photostability in various beverages and good photostability in different p H solutions as well.In addition,the probe TPAEQ has been successfully applied to detect the viscosity of various beverages and thickener contents in beverages,and has been utilized to track the viscosity change during the beverage spoilage process.?2?The near-infrared fluorescent probe?TPAQS-NO₂?for measuring the hypxia level in the organism has been designed and synthesized.The probe with D-?-A structure and large Stokes shift?186 nm?has been prepared by using the triphenylamine as the electron donor?D?,and quinolinium as the electron acceptor?A?.The intermediates and final probe have been characterized by nuclear magnetic resonance?NMR?and high resolution mass spectrometry?HR-MS?,and the spectral properties have been tested as well.The detection mechanism has been verified.In the presence of nitroreductase?NTR?as one kind of hypoxia biomarkers,the aromatic nitro group is reduced by NTR and turns into the hydroxyl as electron donor group.And the fluorescent probe turns into TPAQS-OH,which is accompanied with the red shift of absorption and emission spectra.At the same time,because of the removal of the aromatic nitro group and the aggregation-induced emission feature of the activated probe,fluorescence enhancement could be observed.In the end,the fluorescent probe TPAQS-NO₂ has been utilized to image the hypoxia status in living cells.The early and advanced tumor models have been established to verify the feasibility of detecting and imaging the hypoxia status by the probe.Furthermore,the cerebral ischemia model has been established to verify the feasibility of detecting and imaging the hypoxia status as well.?3?The near-infrared fluorescent nanoprobe TA-TPABQ for measuring the inflammatory status has been synthesized.The probe with D-?-A structure and large Stokes shift?198 nm?has been prepared by using the triphenylamine as the electron donor?D?and quinolinium as the electron acceptor?A?and a natural polyphenol,tannic acid,through the bornate ester bond.The intermediates have been characterized by nuclear magnetic resonance?NMR?and matrix-assisted laser desorption/ionization time of flight mass spectrometer?MALDI-TOF-MS?,and the final nanoprobe TA-TPABQ has been characterized by the X-ray photoelectron spectroscopy?XPS?and dynamic light scattering?DLS?.The spectral properties have been tested and the recognition mechanism has been investigated.In the presence of hydrogen peroxide as one kind of acute inflammatory biomarkers,boronate ester is cleaved and the probe turns into the reaction product TPAQ-OH,which aggregate in the aqueous media due to the increased hydrophobicity,in the meantime,fluorescence enhancement occurs due to the AIE feature of TPAQ-OH.Finally,the nanoprobe TA-TPABQ has been utilized to image the endogenous and exogenous hydrogen peroxide in living cells.The acute abdominal inflammation mouse model,the acute ankle inflammation mouse model and the acute renal ischemia model have been established to verify the feasibility of detecting and imaging of hydrogen peroxide by the probe.In summary,the near-infrared fluorescent probes with the triphenylamine as the electron donor group have been designed and synthesized with large Stokes shift and aggregation-induced emission feature.The fluorescent probes not only can be applied in the food safety field,but also can be applied in detecting and imaging for some biomarkers in the organism.