Construction Of Aggregation-Induced Emission Probes And Their Applications In Biosensing And Theranostics

Fluorescent probes have broad applications in the fields of bio-imaging,sensing,and theranostics based on their excellent sensitivity and specificity.However,conventional fluorophores,such as fluorescein and rhodamine,usually suffer from drawback of aggregation-caused quenching(ACQ).To tackle this challenge,aggregation-induced emission fluorogens(AIEgens)have recently attracted much attention and have shown significant advantages in terms of high emission efficiency in the aggregate state,large Stokes shift,strong photostability,and excellent biocompatibility.Inspired by the advantages of AIEgens in the biomedical fields,we herein developed AIE-active probes with azafluorenone and benzophenanthridine skeletons based on the effects of restriction of intramolecular motion and twisted intramolecular charge transfer mechanisms,et al.,then systemically investigated their photophysical properties.The AIE-active probes were further used for dual detection of bioaccumulated metal ions and nucleus-targeted cancer theranosticsFirstly,we systematically summarized the applications of AIE probes in detection of heavy metal ions and photochemistry-regulated imaging and theranosticsSecondly,we developed an AIE-active probe of 2-((4-cyano-1-(4-(diphenylamino)phenyl)-9-oxo-9H-indeno[2,1-c]pyri din-3-yl)(methyl)amino)-N,N,N-trimethylethan-l-aminium(2-AFN-I)based on azafluorenone skeleton via one-pot multi-component reaction and further alkylation reaction with methyl iodide.The probe was used for dual detection of biotoxic Hg2+based on the combination of turn-off bioluminescence and turn-on photoluminescence.P.phosphoreum can emit strong fluorescence at a high concentration based on quorum sensing.Hg2+could efficiently quench the bioluminescence of P.phosphoreum by accumulation inside the bacteria and disruption of the quorum sensing.The AIE-active probe 2-AFN-I could enter the damaged bacteria and form aggregates with Hg2+to turn-on fluorescence.This dual detection strategy has shown significant advantages over the conventional single detection method.Then,we prepared a dihydrobenzo[c]phenanthridine alkaloid of DHCHE,which can quickly transform into AIE-active benzo[c]phenanthridine alkaloid of CHE through aromatization-driven photooxidative dehydrogenation reaction.The DHCHE probe can achieve photoactivatable nucleus-targeted imaging and killing of cancer cells with a high spatiotemporal resolution based on its fast entry into cancer cells and in situ generation of nucleus-targeted CHE via photoactivation.The photoactivatable therapy can be used for precise control of the therapeutic dose via turn-on red fluorescence and thus has a promising application in cancer theranosticsFinally,we provided a summary and outlook for this thesis.