Preparation Of AIE Fluorescent Systems And Their Application In ROS Scavenging

Fluorescent sensing systems with the mechanism of aggregation-induced emission(AIE)possess the characteristics of non-fluorescence or weak-fluorescence in the molecularly dissolved state and strong-fluorescence in the aggregation state,which solve the problems caused by the phenomenon of aggregation-caused quenching(ACQ)and promotes the development of fluorescent materials.Imflammation is a physiological response of tissues toward harmful stimuli such as pathogens,cancer cells and damaged cells.This physiological process which is mediated by innate immunity eliminates those harmful stimuli through myeloperoxidase(MPO)–halide system.However,the overproduced reactive oxygen species(ROS)in this process could result in oxidative stress,cell or tissue damage if it is scavenged insufficiently.Taurine,an effective antioxidant,can protect cells and tissues by scavenge ROS.And it was also reported that incorporating taurine is capable of boosting the cellular uptake for intracellular accumulation.Given the above facts,two kinds of fluorescent sensing systems based on AIE effect and capable of tracking the release of taurine were designed and synthesized.The main contents include:1.Two fluorophores namely CTPE and DTPE were synthesized by using tetraphenylethene as substrate and incorporating donor-?-acceptor structure as well as extending conjugation length.They are characterized by large Stokes shift,good photostability,and red / near infrared light emission,which is favourable for the applications in biological field.CTPE-Tau and DTPE-Tau were obtained by coupling hydrophilic taurine to the above fluorephores.They have weak fluorescence because their good hydrophilicity and non-aggregation state.2.In the physiological buffer PBS,the antioxidant taurine can be released upon activation by esterase.In the meantime,the released hydrophobic CTPE will aggregate and could act as the fluorescent reporter for tracking taurine release via aggregation-induced emission.The release rate is determined to be 60% and 75% respectively for esterase at 50 ?g/m L,calculated based on the corresponding working curve.3.The fluorescent sensing systems have been successfully applied to scavenge intracellular ROS and imaging in live cell.We selected phorbol myristate acetate(PMA)-stimulated RAW264.7 cell as a model to investigate their applications in inflammatory cells.The results show that coupling with taurine moiety boosts cellular uptake and the antioxidant taurine can be released to scavenge ROS upon activation by esterase which is overexpressed in inflammatory cells.Meanwhile,the turned–on fluorescence can serve as the indicator for the release of taurine.