Design And Application Of Organic Small Molecular Nucleic Acid Probes

DNA is the germ plasm of the organism, owner of hereditary information and thematerial elements of gene expression, and DNA plays a vary important part in thenatural being movement (biology growth, development and reproduce) and abnormitybeing movement (cancerous breakand cancerous movement). The quantitativeanalysis and differential identification of DNA play an important role in the genome,virus and molecule biology. Because the self-fluorescence of DNA is very weak,which results in low sensitivity and specificity of DNA determination by usingfluorescence of DNA directly. The design and synthesis of nucleic acid probe hasbecome a hotspot of research. In this study, we investigate the interaction of differentDNAsequences with several small organic probes. The main works in this thesis wereshown as follows:1. A new light up fluorescent probe, BMSP composed of phenanthroline and4-(4-methylpiperazin-1-yl)-benzaldehyde was designed and synthesized. BMSPexhibits almost no fluorescence in the aqueous buffer condition, its fluorescenceincreases approximately110～150fold in the presence of parallel G4s but only about6-fold in the presence of single/double-stranded (ss/ds) DNA and21fold in thepresence of antiparallel G4s. Binding studies indicate that the highly selectivefluorescent response of BMSP arises from endstack binding model to G-quartet.2. A new monomethine cyanine dye—MTP was synthesized. the productexhibits almost no fluorescence in the aqueous buffer condition, ts fluorescenceincreases approximately130～180-fold in the presence of parallel G4s but only about50-fold in the presence of single/double-stranded (ss/ds) DNA and25-fold in thepresence of antiparallel G4s, shows that MTP can be used as a probe to distinguishdifferent structure of nucleic acids.3. The interactions between Thiazole orange (TO) and different DNA sequenceshas been studied by UV-absorption, fluorescence and circular dichroism (CD)spectroscopy. The experimental results show that TO can bind to different structuresof nucleic acid, which results in great fluorescence enhancement of TO. Thefluorescence response of TO is not correlated with the affinity of TO and DNA. CDspectroscopy experiment shows that the binding mode of TO and nucleic acid is verycomplex, including the groove recognition and the π-π stacking.