Synthesis And Application Of ONOO^-,HClO And SO₂ Fluorescent Probes

Fluorescent probes have attracted great attention because they have high sensitivity,good selectivity,fast response,noninvasiveness and simple technology.However,most of the fluorescent probes reported are extremely limited in their biological applications due to the traditional aggregation-induced quenching(ACQ)effect.In 2001,the concept of aggregation-induced emission(AIE)was proposed by Tang's group firstly.The fluorescent probe with aggregation-induced emission(AIE)activation can emit weak light in the dilute solution but it can send out strong light with aggregate states which overcome the previous deficiencies in comparison to aggregation-induced quenching(ACQ)and has broad application prospects in the field of biological imaging.Peroxynitrite(ONOO-)has strong oxidization and nitration activity.The abnormality of ONOO-can cause autoimmune disease,inflammation,and cardiovascular diseases.Hypochlorous acid(HClO)has strong oxidizing properties in the immune system and it is an effective bactericide,which can prevent microorganisms from invading the immune system.Compared with combining multiple fluorescent probes to detect multiple analytes in one system,using single dual-functional fluorescent probe can detect multiple analytes,avoiding crosstalk caused by the use of different probes,and it has obvious advantages.Sulfur dioxide(SO2)is a kind of reactive sulfur species(RSS).Its derivatives bisulfite and sulfite have antioxidant properties,which are usually used as additives in food,beverages and pharmaceutical products.Cell viscosity is an important microenvironmental parameter in biological systems which can mainly affect signal transmission,electron transfer,and diffusion of reactive metabolites in living cells.In view of the advantages of aggregation-induced emission and dual-function fluorescent probes,it is of great significance to develop fluorescent probes with AIE luminescence effect to detect ONOO-and HClO and dual-function fluorescent probes to detect intracellular viscosity and SO2.Based on quinoline-malononitrile,tetrastyrene,and benzothiazole as fluorescent signal groups,ONOO",HCIO,SO2 and viscosity fluorescent probes were designed and synthesized.Four fluorescent probes were synthesized in this paper.The specific content is as follows:First,most of the ONOO" fluorescent probes that have been reported are mostly ACQ fluorophores,and the application of the probes is greatly restricted.It is necessary to develop a ONOO" fluorescent probe with AIE mechanism.We chose quinoline-malononitrile as the fluorophore and arylboronic acid pinacol ester as the recognition site,and synthesized the probe QM-ONOO".The probe has typical AIE characteristics,rapid response to ONOO",high sensitivity,low detection limit,and large Stokes displacement.The probe realizes the monitoring of exogenous and endogenous ONOO" in EC1 cells.The probe provides an effective tool for monitoring the changes of ONOO' levels in the physiological environment.Second,apoptosis is a very important physiological process,which is closely related to cancer treatment.It is urgent to develop a fluorescent probe with AIE properties to detect the degree of apoptosis.In this chapter,using quinoline-malononitrile as the fluorophore,a fluorescent probe QM-CIO was designed to detect HCIO and apoptosis.The probe emits far-infrared fluorescence(620 nm),shows excellent AIE properties,specifically recognizes HCIO,and has strong anti-interference ability.Under the induction of the drug CCCP,the probe successfully detects the degree of apoptosis in MCF-7 cells.The probe has the potential to explore the relationship between apoptosis and cancer.Third,we choose the common tetrastyrene fluorophore with AIE properties,introduce ONOO" specific response site pyrylium group,and successfully construct a new type of AIE property fluorescent probe TPE-ONOO for the detection of ONOO-.The probe has high selectivity to ONOO" and strong anti-interference ability.The probe has successfully completed the monitoring of exogenous and endogenous ONOO" in MCF-7 cells.It is a novel strategy to detect ONOO-.Finally,we designed and synthesized the dual-functional ratiometric fluorescent probe HXJ-4 based on the benzothiazole group to detect viscosity and SO2.As the viscosity increases,the probe's fluorescence intensity at 580 nm with increases continuously.After the probe is added with SO2,the fluorescence changes from purple to light red,which can detect SO2"with the naked eye".The probe has good biocompatibility and it successfully achieved the detection of SO2 in MCF-7 cells.