Synthesis Of Multi-Functional FR/NIR Fluorescent Probe With Aggregation-Induced Emission Characteristics And Their Application In Bioimaging And Photodynamic Therapy

Recently,aggregation-induced emission?AIE?characteristic,an outstanding phenomenon that is exactly opposite to the aggregation-caused quenching?ACQ?effect,has attracted increasingly attention for biological applications.The AIE fluorogens generally show very weak fluorescence in the dissolved-state,but turn into highly emissive in the aggregated-state caused by the restriction of intramolecular motions and prohibition of energy dissipation via non-radiative channels.AIE fluorogens have found broad applications in fluorescent?FL?bioimaging and FL sensors.Photodynamic therapy?PDT?is based on the concept that photosensitizer?PS?,upon irradiation,can generate reactive oxygen species?ROS?,which can be exploited to kill cells for cancer therapy.The combination of FL probe and PS will be a powerful tool for monitoring the changes of specific organelles while studying the PDT processes in cancer cells.It is very valued for biomedical application but remained challenging due to the lack of ideal FL PDT agent.In this work,an AIE-active FL probe?AIE-FR-TPP?by conjugation of a far red/near-infrared?FR/NIR,?=650–900 nm?emitting AIE fluorogen with the mitochondria-targeting group,is reported as a dual-functional fluorophore for mitochondrial imaging and PDT.As for bioimaging,AIE-FR-TPP can selectively light up the cellular mitochondria with low working concentration,short staining time and good biocompatibility.As for PDT,the probe can target mitochondria precisely and generate ROS efficiently both in living cells and zebrafish embryos.The probe can generate ROS under a general LED white light irradiation(4 mW cm^-2)with excellent ROS quantum yield of 65%.Moreover,AIE-FR-TPP is capable of monitoring the morphological changes of mitochondria based on the AIE effect.It is noteworthy that a real-time visual PDT process at the organelle level in living zebrafish embryos can be achieved for the first time by using the AIE PS to induce mitochondrial ROS collapse and report the morphological change on site and in time.The combination of bioimaging and PDT not only helps to visualize the morphological changes of mitochondria,but also provides an opportunity for studying the PDT process more completely and deeply.