Design,Synthesis And Application Of Specific Fluorescent Probes Based On Sulfhydryl Reactivity

Thiophenol and biothiol are both small molecules containing sulfydryl,but they have different functions.Thiophenol is widely applied in chemical industry and pharmaceutical engineering.Such kind of sulfhydryl small molecule has extremely high biological toxicity.Exposure to environment thiophenol can cause serious irritation to the eyes,respiratory tract mucosa and skin,causing bronchospasm,pneumonia,pulmonary edema even death in severe cases.Unregulated discharge of thiophenols extremely easy to enter the environment through flowing water,posing a serious threat to aquatic life and human health.Cysteine(Cys),homocysteine(Hcy)and glutathione(GSH)are the most widely and important biothiols,which play key roles in regulating physiological function,biosynthesis and maintaining redox homeostasis.Abnormal levels of biothiols have been linked to the development and progression of serious diseases such as cardiovascular disease,Alzheimer’s disease and cancer.Therefore,effective and sensitive detection of thiophenols in environmental and biological samples would be of great significance for the prevention and control of environmental pollution and clarification of their toxicological properties.Besides,Cys,Hcy and GSH are closely interrelated in vivo.Hcy is the precursor for the synthesis of Cys by methionine,and Cys is the synthesis rate-limited substrate of GSH.GSH could also feedback to regulate the level of Cys.Visually monitoring the mutual synthesis and regulation of biolothiol is of great guiding significance for comprehending the occurrence and development of related physiology and pathological processes.In this paper,to detect thiophenols efficiently and conveniently in environmental samples and monitor the biosynthesis process of biothiols in vivo,two novel fluorescent probes were designed and synthesized based on different sulfydryl reactivity.The research contents are briefly summarized as following:1.For high-activity thiophenols,the probes need to be applied to actual environmental samples to assess and clarify its biological toxicity.However,traditional fluorescent probes detection of thiophenols requires the assistance of organic solvents,which cannot fully reveal the real situation of actual samples.Carboxyl group was introduced into the naphthalimide fluorophore matrix with excellent optical properties to improve water solubility,and 4-nitrobenzene sulfonate was used as a quenching group to construct a PET(Photoinduced Electron Transfer)fluorescent probe 2-1,which reacted with thiophenols through Nucleophilic Aromatic Substitution reaction(S_NAr),showing turn-on fluorescence change.Besides,conveniently,efficiently and sensitively detect ability of probe 2-1 to thiophenols was demonstrated through the test strip,real water samples and cell experiments.2.The relative activity of biothiols are lower than that of thiophenols,but they are widely involved in and regulated life activities in organisms.Visually monitoring of biosynthesis and regulation of biothiols are extremely important for clarifying the complex and ordered physiological functions of biothiol in vivo.The near-infrared fluorescent probe 3-1 is constructed based on the coumarin and introduced sensitizing group boron fluoride.Probe 3-1 equipped with three characteristics:1)Probe 3-1exhibited quikly reaction rate with biothiols,and itself displayed slow dissociation aggregation in the aqueous environment,and the dissociation aggregation products no longer react with biothiols;2)The reaction between Cys/GSH and probe 3-1demonstrated obvious distinctions in activity:a little Cys can completely quench the autofluorescence of the probe,while a large amount of GSH cannot;3)Probe 3-1itself present red fluorescence,which exhibited cyan fluorescence after reacting with biothiols(mainly Cys and GSH,but Hcy was ignored due to its low level),but emited yellow in spontaneous dissociation aggregation in aqueous environment,respectively.Hence,we monitored biothiols deficiency and the process of biosynthesis and regulation between Cys and GSH by tracing the red,yellow and cyan fluorescence emission channels.