Application Investigation Of The Composite Glassy Carbon Electrode Modified With Poly-(amino Acid) /matallic Cyano-bridged Mixed Coordination Polymer In The Electrochemical Analysis

In this thesis, the composites of poly-amino acid, matallic cyano-bridged mixed coordination polymer, chitosan and single-walled carbon nanotubes were chosen to use as the modified materials of electrode. They were decorated onto a glassy carbon electrode individually or simultaneously using the electrochemical polymerization and physical spin-coating method. The combination of these modified materials speeded up the electron transfer of the analytes, improved the selectivity, stability and anti-poisoning capability of the modified electrode. Furthermore, the electrochemical behaviour of some small biomolecules with electrical activity such as NADH, dopamine and uric acid using this modified electrode were investigated. The modified electrode also had been used to build new method for the quantitative analysis of the three small biomolecules.This dissertation consists of four chapters.Chapter 1: The literature review of this thesis.This section was consisted by the following five parts:(1) chemical modified electrodes;(2) the electrocatalysis application of the polymer film modified electrodes;(3) the research current and application of the composite modified electrode;(4) a review about the electroanalytical determination of some biomolecules with electrical activity;(5) the research significance and main content of this thesis.Chapter 2: Investigation of direct electrooxidation behavior of NADH at a composite glassy carbon electrode modified with polyglycine/matallic cyano-bridged mixed coordination polymer.In this study, the composite material that made up polyglycine/metallic cyano-bridged mixed coordination polymers was successfully decorated onto a glassy carbon rotating disk electrode(GC RDE) using electrodeposition. The voltammetric behavior of NADH showed typical direct electrooxidation characteristics on the modified GC electrode. Our polyglycine/Yb-In-Co-Mo O42- MCPs modified GC RDE was able to measure the apparent heterogeneous electron transfer rate constant of NADH during its direct electrooxidation by preventing fouling effects on the working electrode, which would generally cause a decrease in the oxidative peak current of NADH. In addition, differential pulse voltammetry provided a large linear range between the oxidative peak current and the concentration of NADH from 2~1500 μmol·L-1 at the polyglycine/Yb-In-Co-Mo O42- MCPs/GC electrode. Finally, the apparent heterogeneous electron transfer rate constant(ks NADH) of NADH was determined to be 1.73×10-2 cm·s-1 using the polyglycine/Yb-In-Co-Mo O42- MCPs modified GC RDE.Chapter 3: Determination of NADH in yeast tablets at the chemically modified glassy carbon electrode using differential pulse voltammetryIn this study, the composite material that made up polyserine/metallic cyano-bridged mixed coordination/chitosan-single wall carbon nanotubes(polyserine/Yb-In-Co-Mo O42- MCPs/CS-SWCNTs) was successfully decorated onto a glassy carbon electrode using the multi-step electrochemical polymerization and physical spin-coating method. The surface morphologies of the composite modified electrode were characterized by scanning electron microscopy(SEM). The results verified that the composite film modified electrode exhibited the excellent electrocatalytic activity and anti-poisoning capability during the direct electrooxidation process of NADH. In addition, a differential pulse voltammetry provided a large linear range, I(μA) =1.314+0.1149C(μmol·L-1), R2=0.9992 between the oxidative peak current of NADH and its concentration from 4~1000 μmol·L-1 at the modified electrode. The modified electrode displayed good reproducibility and stability in the test solution containing the yeast whose cell wall had been broken. Therefore, the total content of NADH in yeast tablets samples was successfully determined with a recovery of 93%~108% by means of a differential pulse voltammetry. The new established method for the quantitative analysis of NADH was very satisfactory.Chapter 4: Simultaneous determination of dopamine and uric acid at a composite modified glassy carbon electrode using differential pulse voltammetryIn this study, the electrode that decorated by polyserine/metallic cyano-bridged mixed coordination/chitosan-single wall carbon nanotubes(polyserine/ Yb-In-CoMo O42- MCPs/CS-SWCNTs) was used to simultaneously determine DA and UA in their mixture solution. The experimental results showed that the composite modified electrode showed excellent electrocatalytic activity toward the electrooxidation of DA and UA. Moreover, the overlapped peak potential of DA and UA were separated on the composite modified electrode. In addition to, their peak current was linear respond to their concentration. Under the optimum conditions, the calibration curves for DA and UA were in the range of 4~200 μmol·L-1 and 2~200 μmol·L-1 with correlation coefficients of 0.9987 and 0.9981, respectively. The different electrochemical behaviors of DA and UA at various scan rates indicated that the electrode reaction of DA was an adsorption-controlled process, and the UA was diffusion-controlled processes at polyserine/Yb-In-Co-Mo O42- MCPs/CS-SWCNTs/GC electrode.