The Research On Electrochemical Behavior Of Biological Small Molecule And Its Interaction With DNA

It is well known that deoxyribonucleic acid (DNA) is the transference base of information in the course of life. The destruction of DNA will cause the handicap of life, even discontinuity. So, much attention is paid to the interaction of DNA with other molecules recently. Used modified electrodes with specifically function, some molecules' electrochemical properties have been studying. It could provide the data for the further studding of it interaction with DNA. Studding the mechanism of DNA interaction with other molecules, people can obtain some data which provide a support to design of some pecific-effect medicines. DNA modified electrode have some advantages over the convential electrochemical methods, such as less sample consumption, higher sensitivity and signal/noise ratio and so has extensive application prospect.Chapter I ReviewIn this part, brief reviews are expressed as fellows: 1. The electrochemistry of DNA and its interaction with target molecules(1) Electrochemistry of DNA(2) The interaction of DNA with other molecules; 2. The biosensor of DNA(1) The preparing methods of DNA modified electrode(2) Hybridize indicator(3) The developing and application of DNA electrochemical biosensor.Chapter II Studies on the electrochemical behavior of 3 — nitro-benzaldehyde thiosemicarbazone at glass carbon electrode modified with nano-γ-Al₂O₃nano-γ-Al₂O₃ is dispersed onto the glass carbon electrode (GCE) by polishing. This nanostructured modified GCE exhibits a great enhancement to the redox responses of 3— NBT. In comparison with bare GCE, 3—NBT gives a more sensitive voltammetric response because of the nanoparticle's unique properties. The lowest detectableconcentration (3σ) of 3—NBT is estimated to be 1.18× 10^-6 (accumulation for 4 min). The linear relationship between peak current and concentration of 3—NBT holds in the range 1.0 × 10^-5 M to 1.0 x 10^-4 (r =0.9981). The electrochemical properties of 3-NBT on this modified electrode have been investigated with various electrochemical methods. The results indicate that the transference of one electron and one proton involves electrode radical reaction processes I and II, respectively. The coverage value (G) of 1.62 × 10^-9 mol cm^-2 was calculated and the electrochemical parameters, diffusion coefficient D (2.54 × 10^-3 cm²s^-1, 2.03 × 10^-3 cm² s^-1) and reaction rate constant k_s (5.9573 s^-1 7.15 × 10² cm s^-1) were obtained for quasi-reversible system I and irreversible system II, respectively. Chapter III Electrochemical study on the behavior of Morin and interaction with DNAVoltammetric behavior of Morin was studied in 0.1 M HAc—NaAc+50 mM KC1 (pH=3.4) solution at glassy carbon electrode (GCE) using cyclic voltammetry (CV). Morin showed an irreversible anodic peak at 0.720 V in CV which were involving two electrons and two protons. Also the interaction of Morin with double-stranded calf thymus DNA (ctDNA) was studied by CV at GCE with an irreversible electrochemical method. As a result of reaction with ctDNA, the voltammetric peak of Morin was a position shift and the peak current decreased. The diffusion coefficients of both free and binding Morin (D_f =1.1086×10^-7 cm² s^-1 D_b=8.2544×10⁹ cm² s^-1), binding constant (K=1.7765×10⁷ cm³ mol^-1), and binding site size (5=0.8510) of the Morin—DNA complex were obtained simultaneously by nonlinear fit analysis. The results demonstrate that Morin can bind to ctDNA in 0.1M HAc—NaAc + 50 mM KC1 (pH=3.4) solution and the ring B of Morin intercalates between the DNA base pairs.Chapter IV Electrochemical studying on behavior of Eu-Mo₂ complex and interaction with DNAThe electrochemical behavior of Eu-Mo₂ and its interactions with calf thymus DNA were studied using cyclic voltammetry (CV) and double potential step chronocoulometry (DPSCC) at glass carbon electrode (GCE) and DNA modified GCE, respectively. Information such as diffusion coefficient (D), rate constant (k_s) of EU-Mo₂ and intrinsic binding constant (K), binding numbers (n) of bound sp...