Effect Of Metal Ions On The Conformation Of Special DNA Sequences

Detection of heavy metal ions plays an important role in human health and the environment monitor. Recently, it is a highlight to detect heavy metal ions using bio-molecular nucleic acid as the biosensor. However, during the research of biosensor, there was still some interference of other metal ions. This thesis studied the effect of different ions on the conformation of special DNA sequences in the detection of Pb²⁺ and Hg²⁺ respectively.This thesis first studied the effect of Pb²⁺, Zn²⁺ and Mg²⁺ on the conformation of Pb²⁺-dependent DNAzyme using Circular Dichroism. The results suggested that Zn²⁺ had certain influence on the conformation of Pb²⁺-dependent DNAzyme.In the experiment of Hg²⁺ detection, a fluorescence-labeled DNA (D-ODN-F) was adopted to detect Hg²⁺ in aqueous solutions through the fluorescence quenching. Interference of other metal ions on the detection Hg²⁺ was studied under different temperature and D-ODN-F concentrations. It was indicated that the suitable temperature 20℃for the detection of Hg²⁺. At that temperature, low concentration of D-ODN-F was disadvantageous in Hg²⁺ ions detection. However, when the concentration of D-ODN-F was up to 60 nM, interference of other metal ions could be ignored. Circular Dichroism and Natural Polyacrylamide Gel Electrophoresis experiments indicated that other metal ions (Mg²⁺, Pb²⁺ and Cu²⁺) had some influence on the conformation of ODN.