Dual-emissive Polymeric Probes With Phosphorescent Iridium(?) Complexes:Design,Synthesis And Applications In Bioimaging

The balance of microenvironmental factors including temperature,pH,and reactive oxygen/nitrogen species(RONS)is crucial to maintain normal physiological activities and functions in living organisms.Many studies have shown that the imbalance of microenvironmental factors may be involved in tumor or pathological processes.Thus,accurate measurement of the microenvironmental factors in living organisms in real time is beneficial to understanding of physiological processes and contributes to the precaution,diagnosis and treatment of diseases in time.As an indispensable tool,luminescence bioimaging is widely used for its high spatial resolution and sensitivity,non-invasiveness,real time and convenience.However,it often suffers from low depth penetration,nonspecific background fluorescence in biological system and error induced by variable concentrations of probe and fluctuation of power.Developing probes suitable for self-calibrating ratiometric luminescence imaging is a useful approach to avoid the problem arising from uncertain concentration of probe and fluctuation of excitation power.In addition,with the utilization of long-lived luminescent probe,the interference from intensive background fluorescence could be effectively attenuated in complex environment via time-resolved luminescence technology.Therefore,we prepared a series of duel-emissive probes for the specific detection and imaging of microenvironmental factors by incorporating two long-lived phosphorescent iridium(?)complexes exhibiting rich long-lived triplet excited states into functional polymer.With the ratiometric luminescence imaging and time-resolved luminescence imaging technologies,the temperature,pH and RONS determination with high signal-to-noise ratio(SNR)have been realized in the complex living organisms.The research content of this thesis includes the following parts:1.Phosphorescent polymeric thermometers for in vitro and in vivo temperature sensing with minimized background interferenceA dual-emissive phosphorescent polymeric thermometer has been developed by incorporating two long-lived phosphorescent iridium(?)complexes into an acrylamide-based thermosensitive polymer(P3).Upon increasing temperature,this polymer undergoes coil-globule transition,which leads to a decrease in polarity of the microenvironment surrounding the iridium(?)complexes and hence brings about emission enhancement of both complexes.Thus,the polymer has been used for temperature determination in vitro and in vivo via ratiometric luminescence imaging.More importantly,by using the long-lived phosphorescence of the polymer,temperature mapping in zebrafish has been demonstrated successfully with minimized autofluorescence interference and improved SNR via time-resolved luminescence imaging.This is the first example to use luminescent thermometer for in vivo temperature sensing.2.Self-calibrating phosphorescent polymeric probe for evaluation of acidification in living cell and digestive tract mucosa in zebrafishA self-calibrating ratiometric pH probe(P-pH)which displays two emission bands has been prepared by immobilizing two long-lived phosphorescent iridium(?)complexes that are pH-responsive and-inert,respectively,into water-soluble polyvinyl pyrrolidone.Owing to the excellent sensitivity and outstanding selectivity of the nanoprobe toward pH,it was used for mitochondrial acidification and lysosomal alkalization in living cells via ratiometric luminescence imaging.More notably,taking advantage of the long-lived phosphorescence of P-pH,the reliable evaluation of microenvironmental pH regulation has been carried out in digestive tract mucosa in zebrafishes with diminished autofluorescence interference and improved signal-to-noise ratio via time-resolved luminescence imaging.3.Dual-emissive phosphorescent polymetric probe for exploring the drug-induced liver injury via imaging of peroxynitrite elevation in vivoA near-infrared dual-emissive phosphorescent polymetric probe(P-ONOO)has been developed for rapid and selective detection of perxoynitrite(ONOO~-).The peroxynitrite sensing in vitro and in vivo with high SNR was realized via ratiometric imaging and time-resolved luminescence imaging.In particular,with the utilization of P-ONOO,the direct visualization of elevated endogenous peroxynitrite in the ketoconazole-induced liver injury has been realized for the first time,which are new evidences for that ketoconazole can lead to depletion of hepatic reductive substance.We also demonstrated that N-Acetyl-L-cysteine(NAC)is an alleviator but not a radical cure for ketoconazole-induced liver injury,which would contribute to reveal the ill-defined mechanism of ketoconazole-induced hepatotoxicity and develop new means for treatment.