Spectrometric And Electrochemical Studies On The Interaction Of Small Molecule With DNA

This paper reviewed the interaction of many kinds of small molecule with DNA, and combined spectrometric and electrochemical methods with chemometrics to study the interaction of some small molecule with DNA, which can solve some problems, which are not resolved by general methods.The work is divided into five parts.Part 1This paper reviewed the importance of DNA in living systems, the structure characteristics of DNA and the binding mode between DNA with different type of some small molecule which can be divided drugs, metallic complex, spectral probes, organic reagents and so on. On the other hand, a review on the recent advances of the determination of nucleic acids by some methods such as spectrophotometric method, fluorescence method, electrochemical method and other methods, is presented, and the possibility of the application of chemometrics in this field has also been discussed.Part 2In this study, we have shown with the use of UV-visible spectrophotometry and the constant wavelength synchronous fluorescence spectroscopy (CW-SFS) techniques that the pharmaceutical drug, chlorpromazine hydrochloride (CPZ), intercalates into the deoxyribonucleic acid (DNA) double helix by partial exchange with the Neutral Red (NR) molecular probe.We have also demonstrated that with the use of three way data plots it is clear that it is important to have well defined methodology for the selection of the important CW-SFS method parameter, AX. Ad hoc selection of this parameter, or even that based on experience, can readily lead to serious errors, which subsequently can be transferred to the interpretation of results. The said three way plots provide a straight forward diagrammatic method, which improves the selection process of a satisfactory value for AX.Finally, we used PARAFAC modeling to resolve the complex three-way CW-SFS data, which provided simultaneously the concentration information for the three reaction components, NR, CPZ and NR-DNA, for the system at equilibrium. This PARAFAC analysis indicated that the intercalation of the CPZ molecule into the DNA proceeds by exchanging with the NR probe, and can be attributed to two parallel reactions.Part 3The constant wavelength synchronous fluorescence spectroscopy (CW-SFS), UV-visible absorption spectroscopy and voltammetry were used to investigate the competitive interaction of deoxyribonucleic acid (DNA) with copper (II) complex of 1,10-phenanthroline ([Cu(phen)₂]²+) and fluorescence probe Neutral Red (NR) in the tris-hydrogen chloride buffer of pH 7.2. The results shown that both [Cu(phen)₂]²+ and NR molecular can intercalates into the DNA double helix layer, and there is a competition between these two interactions. Furthermore, chemometrics approach, parallel factor analysis (PARAFAC), was used to resolve the measured three-way CW-SFS data, which provided simultaneously the concentration information for the three reaction components, NR, [Cu (phen)₂]²+ and NR-DNA, for the system at each equilibrium point. This PARAFAC analysis indicated that the intercalation of the [Cu (phen)₂]²+ molecule into the DNA proceeds by exchanging with the NR probe, and can be attributed to two parallel reactions.Part 4The interactions of methylene blue (MB) with DNA have been investigated by the means of voltammetry and spectrometric methods such as spectrophotometric method and fluorescence method. According to the experimental phenomena and data, it can be inferred that the main binding model of MB to DNA may be electrostatic binding under our experimental conditions. The study of tetracycline-Al3+(TC-AV⁾ with natural and denatured DNA were assessed employing spectrofiuorometric and the constant wavelength synchronous fluorescence spectroscopy (CW-SFS) techniques. The result of experiments is similar to the interaction of MB with DNA, that is to say, the main binding model is also electrostatic binding. With the use of the parallel factor analysis method to a three-way data array of CW-SFS, the interaction of tetracycline-Al3+ with DNA have been studied by using the fluorescence probe MB. The research methods simultaneously resolved the variations of the equilibrium concentration of the three species MB, TC-A13 and the complex TC-A13+-DNA in the reaction mixtures and showed the interaction model of TC-A13+ of DNA. This method avoids the use of Scatchard equation or plot for the model elucidation.Part 5The interaction of Neutral Red (NR) to DNA was investigated at tris-HCl (pH3.5) buffer using a combination of UV-visible spectrophotometry and the constant wavelength synchronous fluorescence spectroscopy (CW-SFS) techniques. A significant binding of NR to DNA was observed and indicated the binding is electrostatic in origin. On the other hand, the research of ciprofloxacin(CPFX) to DNA was studied by electrochemistry methods, UV-visible spectrophotometry and the constant wavelength synchronous fluorescence spectroscopy (CW-SFS). The binding is also electrostatic in origin. Furthermore, PO43* was also used to discuss the binding of ciprofloxacin to DNA, and received the same results. At last, chemometrics approach, parallel factor analysis (PARAFAC), was used to resolve the measured three-way CW-SFS data, which provided simultaneously the concentration information for the two reaction components, NR and CPFX, for the system at each equilibrium point.