Design,Synthesis And Biological Application Of Redox-responsive Twin-disulfide Bonds

The property of the connection key plays a decisive role in the design and synthesis of the molecule applicated in fluorescent probe or a drug delivery system.Based on the different redox environments in the organism and the response properties of the disulfide bond to redox potential,the disulfide bond is widely used in the design of the connection in the field of biomedicine.Compared with other regulatory methods,disulfide bonds have higher response sensitivity,biocompatibility,blood circulation stability and other advantages.But most of the disulfide bonds used in biological materials maintain a single linear response mode,which can not control the stability differences of disulfide bond in different conditions like intracellular accurately.So,people try to improve the property of disulfide bond from external factors such as increasing the steric hindrance or changing the microenvironment,in order to make it better applied to the biological field.However,these methods are less effective.So we try to change the disulfide bond from the nature of the it-its response,so that it is better applied to the biological field.In order to solve the problems above,our group has previously reported a twin-disulfide bond system based on rigid naphthalimide(NDI).We found that different from the mono-disulfide bond changing the linear rate in a single way with the concentration of reducing agent,double disulfide bond can lead to a reversible exchange reaction within the molecule and change the disulfide bond reduction mechanism to make it has a unique nonlinear response property to the redox environment.However,the interaction between molecules in NDI cause its poor water solubility,greater steric hindrance,poor cell response and other defects which limited its further application.In this paper,we designed and synthesized a series of rigid mercapto molecules with benzoic acid as matrix.The stability and responsiveness of mono-and twin-disulfide were investigated by oxidation-reduction kinetics.The double-sulfide molecules were used to construct the twin-disulfide based fluorescent probe system and the fluorescence recovery under different conditions was investigated.Finally,the stability of the probe structure in the intracellular environment was explored by the cell experiment,which laid the foundation for the further application of the structure in the field of controlled drug delivery system.The contents of this paper are divided into five chapters,including the following research:The first chapter,introduces the formation of disulfide bonds in peptides and proteins,the regulation of the structure and function of the disulfide bonds,the structure and function of the disulfide bonds,and the progress of the synthesis of disulfide bonds in the biological materials(fluorescent probe molecules and drug release systems)applications.At the same time,reveals the shortcomings of the current application of disulfide bonds in biomedicine,and puts forward the ideas,contents and significance of this paper.In the second chapter,a series of rigid bis-mercapto molecules based on benzoic acid were designed and synthesized.The molecular weight was reduced and the hydrophilicity was improved.The stability of the twin-disulfide bond was controlled by the carbon chain length.In the third chapter,the redox kinetics of the dimer was observed by chromatography and the stability of the dimer was investigated.The ideal molecular was used to design the twin-disulfide fluorescent probe system as the linker.In the fourth chapter,the selected molecules are used as the linker for the synthesis of biomaterials,including the mono-disulfide fluorescent probe with flexible polypeptide and the rigid twin-disulfide fluorescent probe,the fluorescence recovery under different reducing conditions was investigated.In the fifth chapter,summarizes the main work content and innovation of this thesis,and looks forward to the future research direction.