The Research On The Interaction Of The Hexaaza Macrocyclic Copper(Ⅱ) Complex With DNA And Its Analytical Application As Modified Electrode

DNA is the carrier of genetic information and plays an especially important role in the course of genetic. Investigation of DNA is important in the life sciences field. DNA is the main target molecule that exists in anticancer and antiviral therapies. All cell and virus carry DNA. Normal heredity function of DNA depends on the physical and chemical interaction of other molecules with DNA.Interaction of DNA with small molecules, especially drug molecules affected physiological and physical chemical character of DNA and changed the transfer and copy of DNA. Hence it is meaning that interactions of small molecules with DNA are investigated to understand bind of DNA with protein, anticancer mechanism and to design and synthesize new drug. In medicament, it possible to foresee major steps forward in our understanding of the molecular basis of disease, both from attack by external pathogens and internally from variations within the human genome resulting in a plethora of new molecular therapeutic targets for drug design and discovery.A variety of techniques from molecular biology have been used in research laboratories to study the effects of DNA binding small molecules, such as the gel mobility shift assay, ¹H NMR, DNA foot-printing assay, and fluorescence-based assays, UV-Vis spectrum and viscometry.The first Part: General Introduction and ConclusionIn this part, the development in the studies of DNA, including sturcture of DNA, interaction of DNA with other matter and the mothods about interaction of DNA and small molecule. It is important to study DNA interaction with drug in theory and in practice. Reports about the action of the porphyrin that alkyl connected N-position with DNA are very few in the word. And we study action of methylene blue with DNA solution by mainly electrochemical methods.The second part: Study on DNA Cleavage by the Hexaaza Macrocyclic Copper(II) ComplexIn this paper, we first synthesized Cu(II)L which has a octahedral structure similar to some natural complexes, such as chlorophyll, hemoglobin, vitamin B12 and other bioenzymes, and studied its binding properties to calf thymus DNA by different spectroscopic methods and pBR322 DNA cleavage experiment. Our purpose was to understand the selectivity and efficiency of DNA recognized and cleaved by macrocyclic copper complex, and to develop new effective antitumor reagents or useful DNA probes.The interaction of this complex with calf thymus DNA has been explored by using absorption, emission, viscosity measurements, electrochemical studies and DNA cleavage. From absorption titration data, the bind constant of Cu(II)L with DNA was calculated to be (2.4±0.02)×10⁴ M^-1 Quenching fluorescence is observed for DNA-EB system when Cu(II)L was added, the relative viscosity of DNA decreased with the addition of Cu(II)L. All of the experimental results indicate that the complex bind to DNA by non-classical or partial intercalative interaction. The complex has also been found to promote the cleavage plasmid pBR 322, in the presence of H₂O₂ and ascorbic acid. The hydroxyl radical is suggested to be the reactive species responsible for the cleavage. The cleaving mechanism for the Cu(II)L complex has been proposed.The third part: Electrochemical detection scDNA cleavage in the presence of hexaaza macrocyclic copper(II) complexIn this study, oxidative breakage DNA by the reaction of Cu(II)L with H₂O₂ and ascorbate has been investigated by gel electrophoresis experiments. In electrochemical experiments, the on scDNA-modified glassy carbon electrode(GCE) is cleaved by the Cu(II)L and redox changing of the metal catalyst without adding any other reagents. Above all, the need concentration of scDNA is much lower than that of gel electrophoresis experiments and the process of the performance is easy. Furthermore, Cyclic Voltammetry(CV) and A.C. Impedance which are performed to monitor scDNA cleavage at the scDNA-modified glassy carbon electrode (GCE), are fast, simply and high efficient. The mechanism of the damage can be suggested: Fenton.The fourth part: Electrochemical behavior of hexaaza macrocyclic Copper(II) complex modified Au electrode and Its analytical application DA is a ubiquitous neurotransmitter in mammalian brain tissues and frequently coexists with AA. DA plays a very important role in the functioning of central nervous, renal, hormonal and cardiovascular system. However, it is known that at a most solid electrode the oxidation peaks of AA and DA are same potential and overlap. This result leads an incorrect measurement of DA. So it is essential to develop rapid and simple electrochemical methods for the determination of the concentration of DA. For improving selectivity of detection of DA, many different strategies have been used to modify the electrode surface.A hexaaza macrocyclic copper(II) complex modified Au electrode (Cu(II)L-TCA/Au) was fabricated. The electrochemical behaviors of ascorbic acid and dopamine at the Cu(II)L-TCA/Au had been studied. Scanning electrochemical microscopy (SECM) was employed to study the electrochemical performances of the modified gold electrode indicating different feedback modes at differently modified surfaces. The Cu(II)L-TCA/Au showed an excellent electrocatalytic activity for the oxidation ascorbic acid in pH 4.0 buffer solution. The content of vitamin C of the orange juice was detected without any other pretreatment of the samples and the result was in agreement with those obtained with other methods. The experiments demonstrated a good precision, sensitivity, and lower detection limitation at themodified gold electrode.The modified electrode was an effective mediator for the electrocatalyticoxidation of the ascorbic acid and dopamine and the modification allowed dopamine to be determined in the presence of ascorbic acid in the range from 1mmol to 5mmol in pH 7.6 Tris-HCl buffer solution. The detection limit(S/N=3) obtained by differential pulse voltammetry was 1.8×10^-8mol/L.