The Immobilization Of Nano Au On The Electrode And Its Applications In The Electrochemical Sensor

1 Colloid Au-enhanced DNA immobilization for the electrochemical Characterization of gold electrodes modified with DNA1 .Colloid Au-enhanced DNA electrochemical Characterization(Part I)Colloidal Au were used to enhance the immobilization amount of DNA on a gold electrode, which was modified with calf-thymus DNA(CT DNA) by linear sweap voltammetry (LSV) adsorption. The DNA modified electrode were electrochemically characterized with Co(bpy)33+, a electroactive DNA-binding complex, as an indicator. Self-assembly of approximately 16nm diameter colloidal Au onto L-cysteine modified gold electrode result in an easier attachment of a mercaptohexyl group at the 5-phasphate end on the gold electrodes. And therefore an increased capacity for nucleic acid amount incurred on the electrode. The amount of Co(bpy)33+ enriched bythe layers of DNA was estimated from the peak charge of 5mM Co(bpy)3 reduction at the electrode obtained by cycle voltmmetry(CV). The stability of the DNA-modified electrode was investigated and the results obtained exhibits that the colloidal Au make the DNA-modified gold electrode stable to alkali, acid and boiling water compared to the bare gold electrode. 2.Colloid Au-enhanced DNA electrochemical Characterization (Part II)Colloidal Au were used to enhance the immobilization amount on a gold electrode which was modified with calf-thymus DNA(CT DNA) by Linear Sweap Voltammetry (LSV) adsorption. The DNA modified electrode were electrochemically characterized with Co(bpy)33+, a electroactive DNA-binding complex, as an indicator. Self-assembly of approximately 16卤2.3nm diameter colloidal Au onto cysteamine modified gold electrode result in an easier attachment of a mercaptoexyl group at the 5-phisphate end. The amount of Co(bpy)33+ enriched by the layers of DNA at the electrode was estimated from the peak charge of 5mM Co(bpy)3 +reduction at the electrode obtained by cycle voltmmetry(CV). We also investigated the stability of the DNA-modified electrode. The DNA modification layer on bare gold surfaces is unstable to alkali and heat, but stable to acid solution. The DNA modification layer modified colloid Au is very stable to alkali and acid. It is also stable in boiling water for 10 min. A comparison of modification of gold, platinum and glassy carbon with DNA was carried out. 2. Assembly of Au Nanoparticles by Lysine-Lysine Dipeptide Used in the DNAModified electrodeThis part reports the assembly of Au nanoparticales into 3-D network structures mediated by Lys-Lys. The condensation of Lysine residuces mainly results in the formation of dipepide. Two lysine molecules are connected together to form dipepite(Lys-Lys) use of linker such as EDC. As a result, the gold nanoparticles are assembled into network array linked by Lys-Lys. The electrode was modified with calf-thymus DNA(CT DNA) by Linear Sweap Voltammetry (LSV) adsorption, cycle voltmmetry(CV) and TEM was used in the experiments. 3. Study on the Interaction between Azure and dsDNA from calf thymusThe interaction between Azure and DNA was studied by using of cyclic voltammetry and UV spectroscopy. As a result of the interaction between azure and DNA, an increasement was observed for the Azure-or DNA-modified glassy carbon electrodes. Changes in peak potential and peak current occurred, after the absorbed Azure reacted with DNA absorbed on glassy carbon electrodes. Results obtained by UV sepectroscopy indicate that interaction and electrostatic forces bind Azure and DNA molecule up in PBS buffer. Both cyclic voltammetry and spectroscopic method have been proved to be rapid, cheap and simple methods.