Design,Synthesis And Application Of Several Organic Small Molecule Fluorescent Activity-based Probes

Activity-based fluorescent molecular probes are the preferred types among small molecule probe design due to their specificity,excellent bio-permeability,efficient imaging capabilities and easy sample preparation.Fluorescent probes have many limitations due to their own properties affecting the response signals,so their quantitative tracking ability and self-calibration effect need to be optimized and better applied in complex physiological and pathological environments,such as cells,deep tumors,diseased tissues and animals.Thus they have potential in applications of the clinical tracking therapies.This work include four major aspects.Through the understanding of the structural composition,design principles and mechanism of the fluorescent probes,four novel reactive small molecular probes,including Fep,FAP,CP2 and HP,were synthesized and evaluated to detect various important small molecules and ions,and characterized by nuclear magnetic,mass and infrared spectra.1)The ability of iron to circulate between multiple redox states is critical for catalyzing chemical conversion in biological systems.Ferroptosis is a novel form of cell death associated with iron deposition.It is particularly novel to study effective chemical probes that can selectively track the content of active ferrous ions in vivo which monitors iron death.In this paper,a new fluorescent probe,Fep,has been synthesized by N-oxidation oxidation of dialkylarylamine,the state of ferrous ions was effectively monitored by a distinct a 12-fold "turn-on" response signal appears at the maximum emission spectrum of 636 nm and the reaction could be achieved within 5 min.The probe showed excellent selectivity and sensitivity.An excellent linear dependence between the fluorescence intensity and the concentrations of Fe2+(0-50?M)was observed,and the detection limit reached 0.08 ?M.Thus,this probe could be used for quantitative determination of Fe2+ in the environment and further realizing the fluorescence imaging in living cells and in vivo.These properties can elucidate the biological and pathological state of Fe2+during ferroptosis.2)Formaldehyde is a highly toxic compound of biological organisms,and its strong interaction with biomolecules leads to their inactivation.This paper introduced a new ratiometric fluorescence sensor FAP based on quinoline,which is designed by the 2-aza-Cope rearrangement reaction.After the reaction with formaldehyde,the fluorescence emission spectrum was moved to 570 nm from 495nm and the change of fluorescence intensity ratio up to nine times.The bathochromic fluorescence emission could be efficiently specifically report formaldehyde real water samples.The fluorescent property of the probe was superb with the ?=0.72 and it is also used for the first time to track endogenous formaldehyde in Arabidopsis tissue.These can help to understand the metabolic mechanism of formaldehyde in plants,thereby promoting the studies of formaldehyde-related physiological and pathological researches.3)Cysteine plays a crucial role in the synthesis,detoxification and metabolism of cellular proteins.In this paper,a novel fluorescent probe.was designed to trace dynamic cysteine/cysteine by using the dicyanoisoferone electron acceptor group as an effective fluorescent chromophore.Using the classical structure of acryloyl chloride as a recognition group,a synthetic fluorescent probe CP2 was designed by sulfhydryl redox state.It can be applied to all environments with pH 7-11,and the probe toxicity was low,for the cell survival rate was still over 80%at 25 ?M.It could enter the cell process and monitor the dynamic activity of cysteine/cystine in apoptosis,which showed a favorable advantage in detecting cysteine in cells and had the potential to visualize cysteine in animals.Thus,it can reveal the physiological and pathological functions of cysteine/cystine.4)Abnormal production of hydrogen peroxide can lead to oxidative stress and the development of physiological diseases.In this paper,a new fluorescent probe HP has been reported.The pinacol ester side chain was used as a functional recognition group of hydrogen peroxide,and the fluorescence signal intensity was enhanced after reacting with hydrogen peroxide.This paper establishes the ability of HP with good selectively to detect H2O2 in aqueous solution and living cells.The living cells were treated with the antioxidant N-acetylcysteine(NAC),the NADPH oxidase inhibitor DPI,LPS and reactive oxygen species activator PMA to down-regulate or up-regulate ROS levels.The results indicated that HP had the capability of showing varying ROS levels and it could be deemed to a powerful tool for the progression of diseases such as cancer,neurodegenerative diseases,heart disease and diabetes.In summary,four reactive fluorescent probes were introduced in this paper with their structures were confirmed by nuclear magnetic characterization,and a series of in vitro and in vivo activities were evaluated.They can monitor target analytes in stress state with excellent properties,and also can be applied in different environments or samples.This work provided powerful methods and tools for the study of biological development and diseases.