| In this article, six kinds of schiff base metal complexes were synthesized, whose structures were characterized using infrared (IR) and elemental analysis (EA) methods. Electrochemical and fluorescence spectroscopy techniques were used to study the optimization conditions for the interaction between these compounds and double-stranded salmon sperm DNA to. These sensors were prepared by immobilizing single-stranded DNA probes on glassy carbon electrodes (GCEs) with metal complexes as electroactive indicators to measure the hybridization events between the DNA probes and their complementary DNA fragments. This dissertation comprises by four parts besides the preface.(1) Two kinds of schiff base ligands and its six of metal complexes copper(Ⅱ), cobalt(Ⅱ), nickel(Ⅱ) and manganese(Ⅱ) were synthesized and characterized using elemental analysis and IR spectra.(2) The interaction between the complex of L1CuImH (L1: potassium (E)-2-(2,4-dihydroxybenzylideneamino)propanoate, abbreviated by L1)and double- stranded salmon sperm DNA was studied by cyclic voltammetry (CV). It was shown that the interaction between L1CuImH and DNA is groove binding mode. And the binding stoichiometry(m) and the binding constant(Ka) were also calculated. When R<2.57 (R=[L1CuImH]/[DNA]]), m=0.847≈1, Ka=2.41×103 L·mol-1, and the complex is to be DNA-L1CuImH; when R>3.14, m=2.372≈2, Ka=3.80×109 L2·mol-2, the complex is DNA-(L1CuImH)2. Using L1CuImH as a novel electroactive indicator, a DNA electrochemical sensor based on glassy carbon electrode with covalently immobilized probe ssDNA was conducted. The target ssDNA could be quantified in a range from 9.8×10-9 mol·L-1 to 2.0×10-7 mol·L-1 with a detection limit of 1.15×10-9 mol·L-1.(3) Using the complex of Cu2(L2)2 (L2: sodium (E)-3-((1-carboxyethylimino) methyl)-4-hydroxybenzenesulfonate, abbreviated by L2 ) as electroactive indicators, an electrochemical DNA biosensor was developed. Its interaction with double- stranded salmon sperm DNA (dsDNA) was studied by electrochemical experiments at GCE surface. It was revealed that Cu2(L2)2 could bind with salmon sperm DNA strands mainly by groove mode. The difference of its electrochemical responses between hybridized dsDNA duplex and probe DNA was explored to assess the selectivity of the developed electrochemical DNA biosensor. The complementary target ssDNA could be quantified over the range from 8.07×10-9 mol·L-1 to 5.01×10-7 mol·L-1 with a detection limit of 7.46×10-10 mol·L-1 (S/N=3).(4) Cyclic voltammetry (CV) and fluorescence spectroscopy were used to the interaction of Mn2(L2)2 with double-stranded salmon sperm DNA. It was shown that the interaction mode between Mn2(L2)2 and DNA is intercalation, Using Mn2(L2)2 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 target ssDNA could be quantified in a range from 6.7×10-10 mol·L-1 to 8.4×10-9 mol·L-1 with good linearity and a detection limit of 1.40×10-9 mol·L-1. Compared to DNA electrochemical sensors with ssDNA directly modified on glassy carbon electrodes, this carbon nanotube-based assay dramatically increased the detection sensitivity and selectivity. |
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