Electrochemical And Spectra Studies On The Interaction Of Cyclodextrin Inclusion Complex With DNA

Deoxyribonucleic acid (DNA) is a kind of biologic genetic large molecule, it plays very important role in life genetic code' interpretation, transcription and copy, it is the primary target molecule for most of anticancer and antiviral therapies according to the cell biology. The investigation of the interaction of DNA with other molecules is of great importance in exploreing the structure and character of DNA and their functions. In fact, the interaction of target molecule and DNA take place in physiological environment. So, in virtue of the function of simulate enzyme, cyclodextrin can be utilized to include the target molecule and investigate the interaction of the inclusion complex with DNA. It is helpful to understand some diseases and the mechanism, and offer academic guidance in designing effective drug, and is of great significance in empoldering sensitive chemical probes of polymer structure.In this paper, the interaction of cyclodextrin inclusion complex with DNA have been studied by electrochemistry and Spectroscopy (fluorescence and UV-Vis Spectroscopy) methods. There are four chapters. Chapter IWe describe the structure of DNA, the small molecule species reacting with DNA, the reaction mode, and the investigation methods. At the same time, we describe the reaction of cyclodextrin complex system with DNA, give some advice on the future research. With these described above as basis, the purposes of this article are suggested. Chapter IIThe interaction ofβ-cyclodextrin-thionine inclusion complex with DNA is studied by electrochemical method. At pH 7.2 PBS buffer solutions, thionine withβ-cyclodextrin form a 1:1 inclusion complex, and the stability constant is 458 L mol^-1. The inclusion complex can react with DNA in the model of intercalation, forming a non-electrochemically active supramolecular complex, Their binding numbers and the binding constant were estimated to be 1 and 6.25×10⁴Lmol^-1.Chapter IIIThe interaction between DNA andβ-cyclodextrin(CD)-thionine(TH) inclusion complex was investigated by fluorescence and visible absorption spectrometry. The results showed that TH withβ-CD form a 1:1 inclusion complex with the stability constant of 444 L mol^-1 in the pH 7.2 PBS buffer solutions.β-CD-TH inclusion complex interacted with DNA by intercalative mode. The fluorescence emission peak of inclusion complex shifted toward short waves and fluorescence intensities decreased in the presence of DNA. The quenching constant was calculated to be 6.12×10⁴L mol^-1 by Stern-Volmer method. The quenching mechanism was studied. The interaction ofβ-CD-TH inclusion complex and thionine with DNA were compared. The absorption spectrum of the inclusion complex was decreased and shifted toward long waves in the presence of DNA, confirming the intercalative interaction ofβ-CD-TH with DNA. The binding numbers and the binding constant were estimated to be 1 and 3.47×10⁴ L mol^-1 by spectrophotometry.Chapter IVThe interaction ofβ-cyclodextrin-methylene blue inclusion complex with DNA is studied by electrochemical method. At pH 7.05 BR buffer solution,β-cyclodextrin form a 1:1 inclusion complex with methylene blue, the stability constant is 7366 L mol^-1 . Both the cyclic voltammetric peak potential and peak current of inclusion complex were influenced by the DNA in solution and on DNA/Au electrode. The cyclic voltammograms of inclusion complex in presence of DNA were influenced by ion strength and by 0.001% PDDA polycation. The experiment phenomenon revealed that the interaction betweenβ-cyclodextrin-methylene blue inclusion complex and DNA is in the electrostatic binding mode. The binding numbers and the binding constant were calculated to be 1 and 1.73×10⁴mol L^-1 by current method.