| Biological O2 and its metabolic oxygen-containing species are closely related to various physiological processes and have vital significance in body's respiration,energy metabolism,redox homeostasis,signal transduction and immune defense.However,in most times oxygen-containing reactive species are also considered as "double-edged swords." An outburst of unregulated oxygen species can cause severe oxidative stress,leading to aging and the occurrence and development of malignant diseases(including cancer).Very recently,treatment strategies based on up-regulation of oxidative stress to kill tumors(such as photodynamics,etc.)have been widely proposed,and therapeutic agents such as O2.1O2,and O2·- have been focused on.Herein,desigining highly efficient and sensitive fluorescent dyes that can realize timely non-invasive and visual presentation of the generation,distribution,concentration and subsequent dynamic changes of O2,1O2,and O2·-in complex environments is of great significance.Based on the ICT naphthalimide platform,the mitochondria-accessing ratiometric fluorescent probe NA-T for O2·-was constructed.NA-T consisted of diphenylphosphinyl as the recognition group,amide benzyl alcohol ester as the linker and triphenylphosphorus as the mitochondria-targeting group.Upon being nucleophilicly attacked by O2·-,the diphenylphosphinyl decomposed,and the linker subsequently underwent a self-elimination.The ICT changed,which resulted in significant changes on the absorption and fluorescence spectra.NA-T responses quickly(t<132 s)to O2·-with high sensitivity(detection limit is 0.37?M)and selectivity,which is basically not affected by solvent and pH changes.NA-T has been successfully used for ratiometric imaging of endogenous O2·-in cellular mitochondria and Daphnia magna inflammation models,and can be used in flow cytometry to analyze the O2·produced in drug-stimulated cells.Inspired by the 1O2 mediated damage to amino acids,three "Turn-On" two-photon 1O2 fluorescent dyes NB-TRP,NB-TRY and NB-MOT were designed based on the nitrobenzoxazole platform and biologically rich tryptophan derivatives.By rationally design the electron-donating/withdrawing group on the recognition moiety,the background fluorescence and response sensitivity of these dyes are regulated.NB-MOT,with 5-methoxytryptamine as the recognition group,has the lowest background fluorescence and the highest sensitivity(F/F0?180 fold),and exhibits a dual-mode response to 1O2 based on fluorescence intensity and lifetime.Moreover,NB-MOT has good photo-stability and strong anti-interference ability.It is used for dual-mode imaging of cellular 1O2 and fluorescent detection of 1O2 during photodynamic process.NB-MOT has also been employed to track the metabolic distribution of phototoxic ciprofloxacin in mice and to measure the potential photodynamic stress.Based on the self-sensitization photooxidation strategy,a series of bifunctional photosensitizing dyes BDPs(BDP-C1,BDP-C2,BDP-I,BDP-? and BDP-?)capable of ratiometric O2 sensing were constructed on 2,4-dimethylpyrrole modifided asymmetric BODIPY platform.BDPs series can sensitize O2 to produce 1O2 upon photoirradiation,and react with 1O2 to cause changes on fluorescence ratios and photosensitive properties.Among BDPs,BDP-? demonstrates moderate fluorescence ratio(I605 nm/I633 nm)changes,reserves high 1O2 yield(??=0.43)after photooxidation and holds high phototoxicity(IC50=0.46 ?M).BDP-? was thus applied for ratiometric imaging of the O2 contents in cells and tumors,and for photodynamic therapy to inhibit tumor growth.Moreover,BDP-? was used to evaluate the ability of O2 delivery materials on improving the hypoxic tumor environment. |
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