Design And Application Of Aggregation-Induced Emission Fluorescence Probes For The Imaging Of Active Oxygen Species

Reactive oxygen species(ROS)is an active substance that is widespread in living systems.Hydrogen peroxide(H2O2)and hypochlorous acid(HClO)are two important reactive oxygen species involved in many physiological and pathological processes.Normal levels of H2O2 and HClO can carry out intracellular and intercellular signal transmission and maintain the redox balance in the organism.And their excessive production will lead to oxidative damage,usually accompanied by many diseases such as cancer,inflammation and neurodegenerative diseases.Therefore,it is important to develop effective analytical methods to detect reactive oxygen species in organisms.At present,fluorescent probes based on small organic molecules have been widely used in the detection and imaging of active oxygen due to their advantages such as high sensitivity and good visualization.Studies have shown that tetraphenylethylene(TPE)molecules with aggregation-induced emission(AIE)effects can effectively avoid the aggregation-induced quenching(ACQ)effect of traditional fluorescent probes,thereby expanding the application of probe molecules in the field of biological imaging.Based on this,we have designed and synthesized two kinds of fluorescent molecular probes based on TPE structure to detect H2O2 and HClO in biological environment.The probes can quickly detect ROS and produce significant changes in fluorescence signals.And they have been used for real-time fluorescence imaging in cell and inflammation and cancer models.The main contents are as follows:(1)Using TPE as the core of the fluorophore,we designed and synthesized a fluorescent probe TPE-B with H2O2 recognition ability.A pinacol phenylboronic acid ester is attached at one side of TPE as a recognition group.On the other side,a strong electron-withdrawing group called dicyano was introduced to adjust the fluorescence emission shift of the probe to achieve near-infrared emission of the molecule.When excited with 405 nm excitation light,the probe TPE-B showed a strong orange-red fluorescence.After the addition of H2O2,the borate was removed to leave the phenol structure,which weakened the fluorescence.TPE-B shows good pH stability and selectivity to H2O2.Cell imaging studies have also proven that TPE-B has the ability to detect H2O2 in biological systems.(2)With TPE as the core of the fluorophore,two water-soluble AIE fluorescent probes were developed for rapid detection of HCIO.The probes are COTN and HOTN,both of which detect HCIO by cracking Py+-N+.Compared with COTN,HOTN has higher responsiveness(>1000 times).The response product HOT of HOTN can form intermolecular hydrogen bonds,which enhances the fluorescence response to HClO.And the theoretical calculation data supports the enhanced AIE effect of the existence of hydrogen bonds.Based on its good response to HClO in vitro,HOTN was successfully used for imaging of in vivo inflammation and liver cancer.