Electrochemical And Spectroscopic Studies On The Interaction Of Dye Molecules

With the development of modern techniques of chemical synthesis, compoundseparation, chemical molecular structure analysis, and the theory and investigationtechniques of molecular recognition, recently much attention are paid to the interactionof DNA with other molecules. The interaction between DNA and other moleculesplays important roles in life science and is related to the replication and transcription ofDNA, gene mutation and disease origins. Thus, the study on the interaction is of greatimportance for both therapeutic and scientific reasons. In this paper, the interactions offour dyes, gallocyanine (GC), victoria blue B (VBB), brilliant cresyl violet (BCV) andnew methylene blue (NMB), with DNA were investigated using electrochemical andUV-Vis spectroscopic methods.The interactions of GC, VBB and BCV, respectively, with DNA in solution werestudied in this thesis. After a investigation on the changes of the redox peak currents,the potentials and some electrochemical parameters, such as the charge transfercoeifficient a and the electrode reaction standard rate constant ks, of the dyes beforeand after the addition of DNA, we found that all of them can bind to DNA, and thebinding numbers m and the binding constantsβof the complexes were calculated. Theoptimal binding conditions and the binding models were investigated, respectively.According to the experimental results, the binding mode between GC and DNA isintercalative binding, and between VBB or BCV and DNA is electrostatic binding. Andnew DNA electrochemical analysis methods are established using GC, VBB and BCV as probes, of which the detection limits of DNA are 0.078 mg/L,0.03 mg/L and 0.076mg/L, respectively. Othermgre, the thesis also investigates the interactions of newmethylene blue (NMB) with fish sperm DNA (dsDNA) in solution, and with ssDNAand dsDNA immobilized on the glassy carbon electrode. NMB showed an electrostaticbinding with the immobilized ssDNA, and both electrostatic and intercalative bindingswith the immobilized dsDNA. The binding constants and the electrochemicalparameters of NMB at the bare GCE, ssDNA/GCE and dsDNA/GCE were calculated,respectively. The results of electrochemical impedance spectroscopy, also illustratedthat NMB can identify ssDNA and dsDNA. The difference of interaction properties ofNMB with the immobilized ssDNA and dsDNA has been used for the hybridizationdetection of CaMV 35S gene fragment.