Fabrication And Application Of Three Fluorescent Probes With Aggregation-Induced Emission

Traditional fluorescent molecules have the typical phenomenon of aggregation-caused fluorescence quenching（ACQ）,which causes inconvenience in practical applications.However,aggregation-induced emission（AIE）molecules can effectively overcome the ACQ effect of traditional fluorescent molecules,thus better meeting the requirements of practical applications.Therefore,the AIE field has received much attention.Recently,novel AIE molecules with various functions have been prepared to meet the practical needs in related fields.Based on the above research background,in this work,three novel AIE fluorescent probes were nonfabricated and their applications in biomedicine were systematically investigated.The main contents are listed as follows:（1）The abnormal changes of mitochondrial viscosity in cells have been proved to be related to related diseases,so it is of great significance to develop fluorescent probes that can detect the mitochondrial viscosity in cells.In this work,a novel near-infrared AIE fluorescence probe,TTPB,was fabricated by modifying the traditional tetraphenylethylene（TPE）molecule and further applied to the detection of mitochondrial viscosity.Due to the introduction of TPE and pyridine groups,TTPB had an obvious AIE effect and mitochondrial targeting function.Meanwhile,for the twisted intramolecular charge transfer（TICT）effect,TTPB was highly sensitive to viscosity changes.In the viscosity range of 1.2～956.0 cP,the logarithm of fluorescence intensity(log I,λ_em=620 nm)of the probe showed a good linear relationship with the logarithm（logη）of viscosity,indicating the probe had the ability to quantitatively detect viscosity.Moreover,the probe could also be used to monitor viscosity changes during mitophagy in real time.These results showed that the probe is expected to be used for the early diagnosis of related diseases.（2）Both abnormal viscosity and excessive superoxide anion(O₂^·-)level in living cells often cause a series of biological dysfunction and oxidative damage.However,a great challenge remains in quickly and conveniently detecting the viscosity and O₂^·-levels in living cells.Herein,we fabricated a versatile AIE probe with mitochondria targeting,DTPB,for dual-imaging of viscosity and O₂^·-level in living cells with two different channels.The obtained DTPB contained a diphenyl phosphinic acid unit responsive to O₂^·-,a unit with TICT function responsive to viscosity,and a pyridine cation unit with mitochondria targeting.The results showed that DTPB exhibited a remarkable response to viscosity with a near-infrared emission peak at 671 nm and was highly sensitive to O₂^·-levels with an emission peak at 587 nm.The dual-channel probe has great application prospects in the visual diagnosis of cancer and related diseases.（3）Quantitative detection of heparin is of great significance to ensure the safe use of heparin in the clinic.In this work,a self-assembled fluorescent sensor for rapid detection of heparin was fabricated through electrostatic complexation of chitosan quaternary ammonium salt with 4-（1,2,2-triphenylethenyl）benzoic acid（TPE-COOH）,which has AIE.The analysis of Zeta potential and fluorescence showed that,when the complex encountered heparin,the chitosan quaternary ammonium salt preferentially conjugated with the heparin due to high negative charge density,and then released the AIEgens,resulting in a decrease in the fluorescence intensity of the complex.Therefore,the quantitative detection of heparin was achieved.The results showed that the detection limit of this method was 0.0393 mg/L and the linear range was 0～14mg/L.