Phosphorescent Iridium(Ⅲ) Complexes For Time-resolved Photoluminescence Imaging And Biosensing

Photoluminescence imaging technology based on optical probes,combined with a variety of microscopic techniques represented by laser scanning confocal microscopy,constructs a visual image based on luminescence intensity,which reflects physiological activities at the molecular level such as tissues,signal transduction and metabolic state of organisms.However,during the actual detection,the sensitivity and accuracy are always low due to the light absorption and scattering caused by biomolecules,the concentration reduction caused by photobleaching,as well as the local concentration change caused by uneven distribution of probe molecules and spontaneous fluorescence.Photoluminescence lifetime is an inherent property of molecules,which is extremely sensitive to environmental changes and independent of its own concentration.Time-resolved photoluminescence lifetime imaging microscopy is an important tool for visualizing and quantifying luminescence decay signals.In addition to detecting lifetime signals,photoluminescence lifetime imaging microscopy can detect and analyze multiple lifetime-responsive targets with different luminescence decay rates at the same time,which specifically respose to analytes in the organism.Firsly,the thesis explores responsive behaviours of the luminescent probe to a single bioanalyte in the intracellular environment,and then the joint response of the functional optical probe to multiple targets is discussed,which is helpful to further explore its internal sensing mechanism.The content of the thesis includes the following aspects:1.Responsive luminescence probes used to detect reactive oxygen species,p H and metal ions in the cellsThe intracelluar reactive oxygen species were detected by fluorescent probes based on 1,8-naphthalimide derivatives in real time.The standard linear curve between luminescence intensity and p H and the growth fitting curve between luminescence lifetime and p H are both established by the p H-sensitive optical probe based on the iridium(III)complex.It is studied that the selective quenching of phosphorescence of iridium(III)complex modified with 2,2’-dipyridyl methylamine induced by copper ion.The oxygen interference experiment is carried out.And the photoluminescence intensity and lifetime of the complex are sensitive to oxygen.2.Applications of dual-emissive luminescence probes for multi-target simultaneous detection in the photoluminescence lifetime imaging and biosensing.A kind of dual-phosphorescent emission iridium(III)complex probe is designed which has advantages of multiple luminescence and transition metal complex materials.Two different emission peaks show specific luminescence responses to copper ion and oxygen respectively,and the luminescence signals from different channels have different luminescence decay rates.Therefore,it allows simultaneous processing from two lifetime channels by time-resolved photoluminescence lifetime imaging microscopy.Secondly,a polymeric luminescent probe is designed and explored,which is composed of a fluorescent compound based on 1,8-naphthalimide derivatives and a phosphorescent iridium(III)complex.The spectrum of both luminophores overlapped highly but their luminescence lifetimes are 62 times differently.The fluorescence of 1,8-naphthalimide derivatives is quenched by hypochlorite oxidation,and the phosphorescence of iridium(III)complex rises gradually with the increase of p H.As the PLIM images shown,even in the case of overlapped spectrum,the different optical response of the probes to multiple targets can be detected and analyzed in the time domain independently and simultaneously.And it is possible to further explore the organism’s internal sensing mechanism based on the joint analysis of multiple indicators.