Construction Of Photoactivatable Fluorescent Probes And Their Applications In Cell Imaging And Monitoring Of Oxidative Stress

Photoactivatable fluorescent probes,which consist of fluorophores and photo-responsive groups,have been widely used in biomedical research,including the monitoring of organelle or protein movement,the precise killing of cancer cells or bacteria.In recent years,many photo-responsive groups have been developed,such as photocleavable o-nitrobenzyl and coumarin derivatives,photoisomerizable azo and spiropyran derivatives,and so on.However,these photo-responsive groups suffer from the following defects,including complicated synthesis routes,inefficient photochemical reaction and toxic byproducts.In order to overcome the above shortcomings,a series of photoactivatable fluorescent probes based on photo-oxidative dehydrogenation reaction were constructed in this dissertation.Their photophysicochemical properties were first studied.And the probes were then applied in cell imaging with high spatiotemporal resolution and monitoring of oxidative stress.The specific contents are as follows:(1)A photoactivatable fluorescent probe based on photo-oxidative dehydrogenation reaction was constructed by using tetrahydropyridine as photo-responsive group,triphenylamine thiophene as electron-donating group and unsaturated double bond as bridging group.Under white light irradiation with low power,the tetrahydropyridine group can rapidly transform into pyridinium group and water,enhancing the electron-withdrawing ability efficiently,which could lead to an obvious red-shift of the emission.The photo-responsive group of tetrahydropyridine has the advantages of simple synthesis,notoxic byproduct,and rapid and efficient photochemical reaction rate,indicating that tetrahydropyridine,which is substituted by electron-donating groups,is an excellent photo-responsive group with great potential in biomedical applications.Based on this,the probe was further applied in the cell imaging with high spatiotemporal resolution,realizing the light-controlled imaging for the selected cells.(2)The reactive oxygen species(ROS)-induced oxidative stress is accompanied by changes of organelle structure or morphology.However,there is a lack of probes for simultaneous imaging and monitoring of different organelles under ROS stress.Therefore,a photoactivatable probe with the ability for tandem imaging of organelles was constructed by using triphenylthiophene-vinyl-substituted tetrahydropyridine as the photo-responsive group.Under white light irradiation,the probe can not only efficiently generate ROS to induce oxidative stress,but also change its organelle targeting ability and emission color after photoactivation so that to simultaneously monitor the dynamic changes of lipid droplets(LDs)and mitochondria under ROS stress.For example,the probe can selectively stain the LDs with increased membrane permeability,which were induced by oxidative stress,and emits bright green fluorescence,revealing the change of LDs structure under oxidative stress.Also,red-emissive mitochondria were observed after staining with the in situ generated AIEgen by photoactivation.Thus,the morphological changes of mitochondria induced by ROS were successfully monitored.Furthermore,the interplay between LDs and mitochondria was also monitored based on their distinct spectral difference,revealing their close relationship under oxidative stress.In conclusion,based on the photo-oxidative dehydrogenation reaction,several photoactivatable fluorescent probes with tetrahydropyridine substituted with electron-donating groups as the photo-responsive group were constructed in this thesis.They have the advantages of simple synthesis,notoxic byproducts and efficient photochemical reaction.Moreover,they have been successfully applied in cell imaging with high spatiotemporal resolution and monitoring of cellular oxidative stress process.This dissertation not only provides a new method for the construction of photoactivatable fluorescent probe,but also greatly contributes to the study on physiological function of organelles and oxidative stress-related diseases or therapy.