Design And Application Of Nucleic Acid Fluorescence Probes Based On Thiazole Orange

Nucleic acid,as the genetic material of life,nucleic acid,its structural integrity determineshas a significant effect on normal physiological functions,proliferation and differentiation of cells due to its structural integrity.The integrity of the nucleic acid structure also determines whether the organism can grow and develop normally,and the inheritance and variation in the process of reproduction of the organism.The diversity of DNA molecular structure has a great influence on its nature and function.The clinical chemical anticancer therapy is based on the role of DNA as a chemical drug target.This is an effective means of cancer treatment.DNA is also widely used in the diagnosis of diseases and drug design.Therefore,simple and selective recognition with high-sensitivity for determining various structures of nucleic acids has been a great concern for scientists.Due to their high sensitivity,fast response and low cost,fluorescent probes have been widely studied in recent years.In this dissertation,three fluorescent probes based on TO were designed and prepared.Their activities of binding to DNA and entering the cell were explored:1.A new carbon dots?CDs?based nanoprobe for detection of DNA was constructed in this work.Thiazole orange?TO?,a specific organic small molecular probe towards DNA,is covalently linked to the surface of CDs,acting as the recognition element and fluorescence response unit.The nanoprobe only emitted the blue fluorescence of CDs,while TO was almost non-fluorescent in the absence of DNA.Upon addition of DNA,a turn-on emission at 530 nm appeared and gradually increased along with the addition of target DNA,while the fluorescence of CDs kept unchanged,which realized the ratiometric detection of target DNA.The CDs-TO nanoprobe showed good selectivity to double-stranded?ds?and parallel G-quadruplex?G4?DNA over single-stranded?ss?and antiparallel G4 DNA.Moreover,the ratiometric fluorescence nanoprobe exhibited high sensitivity with a low detection limit of 0.90 and 3.31 nM for ssab?a dsDNA?and c-myc?a parallel G4?,respectively.Additionally,the G4/hemin peroxidase activity inhibition experiment demonstrated that CDs-TO bound to the G4s through end-stacking mode.2.TO-NH₂,TO-COOH was synthesized,and the localization of the TO,TO-NH₂,TO-COOH in the cell and the ability of TO entering cells were compared through confocal and flow cell experiments.3.A new fluorescent probe,TO-PDA composed of phenanthroline and thiazole orange was designed and synthesized.Fluorescence response of TO-PDA combined with different DNA was studied.