Studies On The DNA Electrochemical Sensor Based On The Interaction Between Flavonoid Complexes And DNA

This paper can be summarized as follows:(1) The interaction between quercetin and salmon sperm DNA was studied by means of electrochemical method. It was shown that the interaction mode between quercetin and DNA is electrostatic interaction. Using quercetin as the hybridization indicator, DNA electrochemical sensor based on glassy carbon electrode with covalently immobilized probe ssDNA was conducted. The DNA electrochemical sensor can be applied to the recognition of complementary ssDNA segment using probe ssDNA, and the sensor was good selectivity and sensitivity. The complementary ssDNA could be quantified in a range from 4.90×10-8 mol-L-1 to 2.43×10-7 mol-L-1 with a detection limit of 1.32×10-8 mol-L-1.(2) The complex of rutin-Cu(II), C81Cu2O48 (abbreviated by (3R-4H)Cu2, R = rutin), was synthesized and characterized by elemental analysis and IR spectra. Cyclic voltammetry (CV) and fluorescence spectroscopy were used to investigate the interaction of (3R-4H) Cu2 with salmon sperm DNA. It was shown that the interaction mode between (3R-4H) Cu2 and DNA is intercalation, and the binding number of (3R-4H) Cu2 per each base-pair of salmon sperm dsDNA was calculated to be 1, and the binding constant was to be 1.99×106 L-mol-1. Using (3R-4H)Cu2 as a novel electroactive indicator, DNA elecrrochemical sensor based on glassy carbon electrode with covalently immobilized probe ssDNA was conducted. The DNA electrochemical sensor can be applied to the recognition of complementary ssDNA segment using probe ssDNA, and the sensor was good selectivity and sensitivity. The target ssDNA could be quantified in a range from 1.62×10-8 mol-L-1 to 8.10×10-7 mol-L-1 with a detection limit of 2.3×10-9 mol-L-1.(3) The complex of rutin-Mn(II), C54H58MnO32 (abbreviated by (2R-2H)Mn, R =rutin), was synthesized and characterized by elemental analysis and IR spectra. Cyclic voltammetry (CV) and fluorescence spectroscopy were used to investigate the interaction of (2R-2H)Mn with salmon sperm DNA. It was shown that the interaction mode between (2R-2H)Mn and DNA is intercalation, and the binding number of (2R-2H)Mn per each base-pair of salmon sperm dsDNA was calculated to be l, and the binding constant to be 2.22×104 L-mol-1. Using (2R-2H)Mn as a novel electroactive indicator, a novel and sensitive DNA electrochemical sensor was conducted, which was based on multiwall carbon nanotubes functionalized with carboxyl groups, MWCNTs-COOH, for covalent probe ssDNA immobilization. The MWCNTs-COOH-modified glassy carbon electrode was fabricated and probe ssDNA with the 5'-amino groups were covalently bonded to the carboxyl groups of carbon nanotubes. Compared with DNA electrochemical sensors with ssDNA directly modified on carbon electrodes, this carbon nanotube-based assay with large surface area and good charge-transport characteristics dramatically increased the attachment quantity of probe ssDNA and thus the detection sensitivity complementary ssDNA greatly. The target ssDNA could be quantified in a range from 1.60×10-9 mol-L-1 to 4.80×10-8 mol-L-1 with good linearity and a detection limit of 1.0×10-9 mol-L-1.