Synthesis And Application Of Fluorescent Probes For Specific Identification Of Intracellular Components

The observation of cellular and molecular processes in vitro or in vivo is an important area of research in the biomedical sciences.Using chemical probes that are selective for specific targets,precise phenomena such as receptor or protein expression,oxidative stress,enzyme activity and changes in the cellular environment can be studied.Among the various imaging techniques,fluorescence imaging is the most widely used imaging modality due to its obvious advantages such as excellent spatio-temporal resolution,high sensitivity and selectivity,minimal invasiveness and excellent tunability.Today,the rapid development of molecular imaging technology provides a real-time,non-invasive and dynamic means of visualising cells at the molecular level and assessing the physiopathological changes in organelles closely associated with disease.Molecular imaging has demonstrated its superiority in clinical science for diagnosis,prognosis and monitoring of disease progression,as well as helping to select therapeutic strategies,predict or evaluate treatment outcomes,and guide surgeons in surgery.In particular,the development of highly targeted and photostable intelligent fluorescent probes is expected to provide an effective means of visualizing the dynamics of intracellular active molecules in a comprehensive and accurate manner,which is an important way to achieve relevant disease research.In this thesis,two fluorescent probes were designed in order to deeply explore the active molecules inside the cells.The details are as follows.(1)We discovered the positively charged organic molecule Benzothiazole-Anilina,BTA would interact with the intracellular G-quadruplex,during which the single bond rotation of the BTA molecule was blocked,reducing the radiation-free leap,and the fluorescence was turned on,emitting a yellowish fluorescence.At the same time,the structure of the G-quadruplex was stabilized during the interaction between the BTA molecule and the G-quadruplex,thus demonstrating its potential for tumour inhibition.Both cytotoxicity and PI staining experiments revealed that the BTA molecule was more effective in killing tumour cells and less effective in killing normal cells.(2)We designed and synthesized a fluorescent carbon dot that specifically targets lysosomes,allowing for long range imaging of lysosomes in living cells.The nanofluorescent carbon dots DMEDA-CDs were obtained by oxidatively stripping carbon black to obtain carbon dots rich in carboxyl groups,and then modifying N,N-Dimethylethylenediamine(DMEDA)onto the carbon dots through an amidation reaction to obtain blue fluorescent carbon dots.The modification of DMEDA on carbon dots significantly improved the fluorescence quantum yield of carbon dots.A series of cell experiments demonstrated that DMEDA-CDs also have high photostability and low cytotoxicity,allowing long time imaging of lysosomes in living cells.