Design,Synthesis And Biological Application Of Novel NIR Viscosity Probes

Cellular viscosity is a significant intracellular factor influencing the interaction between biomacromolecules,chemical signal transportation and diffusion of reactive metabolites within live cells.Abnormal intracellular viscosity has been linked to disease and dysfunction,so it is important to monitor viscosity at the cellular level.The determination of intracellular viscosity remains a major challenge in current chemical biology.The conventional methods for viscosity measurement using instruments such as a capillary viscometer,a falling ball viscometer,and a rotational viscometer can hardly be applied at the cellular level.In recent years,with the development of fluorescence detection and imaging technology,chemical probes are an ideal tool for detecting intracellular microenvironment.However,there is still a lack of fluorescent probes for detecting cellular viscosity specifically and sensitively.To solve the above-mentioned problem,we designed and synthesized a novel near-infrared viscosity probe and a double-locked mode probe to achieve high-sensitivity imaging analysis of cellular viscosity and hydrogen sulfide.The main contents of this thesis are as follows:Based on the electron donor-acceptor molecular rotor,we designed and synthesized a new near infrared probe DCMN for detecting viscosity.The structure of probe DCMN was fully characterized by ¹H NMR,¹³C NMR and high-resolution mass spectra?HRMS?.The fluorescence intensity of DCMN exhibited an excellent linear relationship with viscosity value,and fluorescence of DCMN is quite stable in different pH solvents at the same viscosity.Besides,bioactive species,such as metal ions,amino acids,reductive species,and oxidizing species,do not interfere with the detection of viscosity.Based on the low biotoxicity,good light stability and low biological background of the probe DCMN,we successfully applied it to the fluorescence imaging viscosity in living cell.The results showed that the viscosity of cervical cancer cells?HeLa?,liver cancer cells?HepG2?and breast cancer cells?MDA-MB-231?was significantly increased by starvation.The intracellular viscosity of HeLa also increased significantly under the stimulation of rotenone or nystatin.The above experimental results indicate that the probe DCMN is expected to be applied in imaging viscosity changes of related diseases in vivo,and provide an excellent analytical means for elucidating the mechanism of disease development.A double-locked mode probe activated by tumor microenvironment-specific DCM-V-H₂S was constructed by introducing 2,4-dinitrobenzenesulfonic ester groups into above viscosity probe structure.DCM-V-H₂S has excellent selectivity in identifying hydrogen sulfide,and can only be activated to emit near-infrared fluorescence in the presence of high viscosity and hydrogen sulfide.It can be used to detect the coexistence of high viscosity and hydrogen sulfide for the first time.