Design,Synthesis Of Novel Reactive Carbonyl Species(RSC) Small Molecular Fluorescent Probes And Their Bio-imaging Study

For a long time,carbonyl species are often considered as a class of harmful substances,such as carbon monoxide and formaldehyde.Prolonged exposure to reactive carbonyl species may lead to many malignant diseases.However,with the in-depth study of reactive carbonyl species,it is found that these reactive carbonyl species are endogenously produced in the organism.The endogenous reactive carbonyl species may be used as the regulating agents of life activities,and participate in the regulation of important physiological processes,such as gene expression and cell signal transduction.Although the traditional detection methods can provide high sensitivity and selectivity to reactive carbonyl species,but these methods require irreparable damage to the sample and couldn't guarantee the integrity of the samples,also cannot achieve real-time monitoring of reactive carbonyl species.Therefore,development of new detection technology with high sensitivity for reactive carbonyl species in the body of the in situ,real-time detection has important guiding significance for the study of the physiological and pathological functions of the reactive carbonyl species in the organism.Fluorescence microscope imaging technology is a kind of analytical method for the detection of bioactive small molecule or cell microenvironment by using fluorescence signal.Fluorescence imaging technology is used to detect the target molecules by means of relevant fluorescent dyes or fluorescent probes.Fluorescence imaging has many unique advantages over traditional detection methods such as nuclear magnetic resonance detection,high resolution mass spectrometry and electron microscopy.First,the fluorescence imaging technology uses laser technology to realize the detection,and the damage to the sample is very small.Second,the fluorescence imaging technology has good selectivity/sensitivity and fast-response,which can realize the in-situ and real-time imaging detection of specific target molecules in biological samples.Third,the fluorescence imaging technology does not need to destroy the biological samples,and the test operation is simple,which has a certain protective effect on the samples.On the basis of literature research,we have constructed four kinds of reactive carbonyl species fluorescence probes with different functions,which make up the deficiency of the reactive carbonyl species fluorescence probes.In the first part,we present the rational design,synthesis,and photophysical property studies of the first two-photon fluorescent formaldehyde probe,Na-FA.Importantly,the highly desirable properties of the probe Na-FA such as a very large turn-on signal(up to 900-fold),a low detection limit(0.7 ?M),and very fast onset(immediately upon incubation)imparted by the unique design strategy of the probe,make it possible to monitor the endogenous formaldehyde in the living tissues for the first time.Furthermore,during the fluorescence assay of the probe,we discovered that sodium bisulfite could act as a simple and convenient inhibitor for formaldehyde not only in the solution,but also in the biological environments.In the second part,we develop the first lysosome-targeted and endoplasmic reticulum-targeted fluorescent formaldehyde probes(Na-FA-Lyso and Na-FA-ER).The detection is based on the condensation reaction of the hydrazine group and formaldehyde to suppress the photo-induced electron transfer(PET)pathway,resulting in the fluorescence increase.The novel probes Na-FA-Lyso and Na-FA-ER show high sensitivity to formaldehyde.In addition,Na-FA-Lyso and Na-FA-ER enable the bio-imaging of exogenous and endogenous FA in living HeLa cells.Significantly,the new probes are employed to visualize the endogenous formaldehyde in the lysosomes and endoplasmic reticulum in the living cells for the first time.In the third part,we design and synthesis the first two-photon fluorescent methylglyoxal probe,named as Na-MGO.The new probe exhibits favorable features including high sensitivity to carbon monoxide and a low detection limit(1.47 ?M).Significantly,the novel probe Na-CO was employed to visualize the exogenous methylglyoxal in the living tissue and zebrafish for the first time.In the fourth part,we describe the development of the first organelle-targeted fluorescent carbon monoxide probe(Na-CO).The new probe exhibits favorable features including a fast response to formaldehyde and high sensitivity to carbon monoxide.Significantly,the novel probe Na-CO was employed to visualize the exogenous carbon monoxide in the lysosomes in the living cells for the first time.In summary,we reported four different functional reactive carbonyl species fluorescent probes.These probes can be used as an effective tool to study the function of reactive carbonyl species in biological samples and provide theoretical guidance for the design of related probes.