Design,Synthesis And Application Of Targeting Fluorescence Probe For Advanced Structure Of Nucleic Acid

G-quadruplexes(G4s)are non-canonical nucleic acids secondary structures which are consisted of guanine-rich nucleotide sequences in the presence of monovalent cations.These structures widely distribute in functional genomic regions and transcripts,which can importantly influence biological processes.Herein,a new targeting fluorescence probe was designed and synthesized to effectively differentiate G4 structures from other nucleic acid forms via various techniques.Furthermore,a K+-driven aptamer sensor was constructed which based on differentiated response of Th T-E for G4 and non-G4,leading to an amplified fluorescence signal in the reporter.The researches are as follows:1)Based on the structural features of Thioflavin T and targeting probe for G4 and the results of molecular docking,a new water-soluble fuorogenic dye Th T-E was designed and synthesized via 1-step reaction.In comparison with Th T,the rings between benzothiazole and aniline of Th T-E have a smaller angle,which is nearly planar surface.Meanwhile,the values of ?G are smaller when Th T-E interacts with G4 s.Therefore,Th T-E is more suitable for G4 detection.2)The selective recognization of Th T-E for G4 s was investigated by various spectra and other techniques.The distinctions of the interactions between Th T-E or Thioflavin T and G4 s were investigated.The fluorescence of Th T-E significantly enhanced when interacting with G4 s,while negligibly changed of its fluorescence interacting with other nucleic acids.Compared with Thioflavin T,Th T-E showed higher binding afnity,selectivity for G4 and little effect on the structure of G4 forming sequences,indicating that Th T-E is more suitable as a probe for G4 recognition.3)On the basis of differentiated response of Th T-E for G4 s and other nucleic acid forms,a highly specific fluorescence sensor for K+ assay is constructed successfully.In the absence of K+,the aptamer displayed a random-coil structure,which resulted in a negligible fluorescence signal of Th TE.In the presence of K+,two aptamers fold into a G4 and bound with Th T-E,resulting in a dramatic fluorescence enhancement of Th T-E.This probe possesses many advantages including simple operation,high specificity,lable-free and low sample volume,which is successfully applied to the assay of K+ in lake water and urine samples.