Studies on the interaction mechanism between hexakis(imidazole) manganese(II) terephthalate and DNA and preparation of DNA electrochemical sensor

The interaction between hexakis(imidazole) manganese(II) terephthalate (Mn(Im)(6)](teph).4H(2)O) and salmon sperm DNA in 0.2M pH 2.30 Britton-Robinson buffer solution was studied by fluorescence spectroscopy and cyclic voltammetry. Increasing fluorescence was observed for Mn(Im)(6)](2+) with DNA addition, while quenching fluorescence phenomenon appeared for EB-DNA system when Mn(Im)(6)](2+) was added. There were a couple quasi-reversible redox peaks of Mn(Im)(6)](2+) from the cyclic voltammogram on the glassy carbon electrode. The peak current of Mn(Im)(6)](2+) decreased with positive shift of the formal potential in the presence of DNA compared with that in the absence of DNA. All the experimental results indicate that Mn(Im)(6)](2+) can bind to DNA mainly by intercalative binding mode. The binding ratio of the DNA-Mn(Im)(6)](2+) association complex is calculated to be 1:1 and the binding constant is 4.44x10(3) M(-1). By using Mn(Im)(6)](teph).4H(2)O as the electrochemical hybridization indicator, the DNA electrochemical sensor was prepared by covalent interaction and the selectivity of ssDNA modified electrode were described. The results demonstrate the use of electrochemical DNA biosensor in the determination of complementary ssDNA.