| Since it was came out in 1975, Chemical modified electrode has been widely applied in Analytical science, Environmental science, Life science, Materials science, Electronics and so on, becoming the active research field in Electrochemical and Electroanalytical Chemistry. A most important application of Chemical modified electrode is electrocatalysis. The purposes of electrocatalysis of Chemical modified electrode for analysis performance main in order to reduce over-potentials, reduce the interference currents and background currents; increase current response, reduce the limit of detection; prevent the adsorption of tested materials and products on the electrode.The polymer films have three dimension configurations, which supplies some available energy field and has a lot of active group. The polymer films have electrochemical catalyze characteristics. On the other hand, the polymer films with selected chemical function group have some special character and expectable reactions taking place on the films. Amino acid is the most essential matter in biological body, which has some special characters for having amino group and carboxyl. Amino acid can be modified on the electrode by chemical way or electrochemical way. The modified electrodes are applied for the determination of biological molecule, organic pollutant, metal ion and so on, which shows some special advantages and has been widely used. Since the discovery of carbon nnaoutbes (CNTs) in the early 90s, much attention has been paid to them. The one-dimensional tubular structure of CNTs has greatly stimulated studies of this novel material in the field of physics, chemistry and material science. Depending on their atomic structure, CNTs behave electronic properties suggest that CNTs have the ability to promote electron-transfer reactions. The determination of small biomolecules such as catecholamine neurotransmitter dopamine, hydrogen peroxide and phenolic compounds is a focal point of research in Electroanalytical Chemistry. Different methods and materials have been used for the modification of electrodes. In this work, we modified different specific materials on the surface of electrodes by electrochemical polymerization, constructing a variety of modified electrodes of different specific function, and studied their properties for selective Electrocatalysis and the determination of the actual sample analysis. These works are divided into three parts:First: A novel biosensor was fabricated by electrochemical polymerization of poly-L-proline (P-LP) and ferricyanide (FC) compound film on glassy carbon electrode (GCE). The compound film modified electrode (P-LP/FC/GCE) shows electrocatalytic activity toward dopamine (DA) in phosphate buffer solution (PBS, pH = 4.0) with a diminution of the overpotential and an increase in peak current. The P-LP/FC/GCE was applied to the electrocatalytic oxidation of DA using cyclic voltammetry (CV) technique. The peak current of DA is linear with the concentration of DA in the range of 1×10-7 to 1.14×10-4 mol/L. The detection limit is 4.4×10-8 mol/L (S/N=3). The P-LP/FC/GCE exhibited an excellent selectivity, sensibility and stability for determination of DA, and can be applied to determinate dopamine injection with satisfied result.Second: A novel method for the fabrication of a hydrogen peroxide sensor was developed by electrodepositing Prussian Blue (PB) on the cetyl trimethyl ammonium bromide dispersing multi-walled carbon nanotubes modified glassy carbon electrode (PB/CTAB-MWNTs/GC). The factors such as the type and acidity of electrolytes, the scan rates and the applied potential that influencing the voltammetric behavior of PB in the presence of hydrogen peroxide were studied in detail. In 0.1 mol/L phosphate solution (pH 5.44) containing 1.6 mol/L potassium chloride, the resulted sensor exhibited a wider linear range from 5.0×10-6 to 8.6×10-3mol/L with a correlation coefficient 0.999. The detection limit of the sensor was 2.1×10-7 mol/L. Such sensor could be used for the determination of hydrogen peroxide in disinfector with good results. Third: A highly selective and sensitive biosensor based on poly (PL-Cysteine) modified glassy carbon (PL-cys/GC) electrode for simultaneous determination of phenolic compounds was described. The PL-cys/GC electrode was prepared by electropolymerization of Cysteine by cyclic voltammetry (CV) method, and its electrocatalysis behavior to phenolic compounds was studied. It showed that the PL-cys/GC electrode possesses an efficient electrocatalytic activety for the electrochemical oxidation of phenol and catechol (CC) in 0.1 mol/L phosphate solution (pH 4.0), and realized the simultaneous determination of phenol and CC. The Linear Range of phenol and CC were 5×10-72.65×10-4mol/L and 2.0×10-62.0×10-4mol/L with the detection limit of 1.0×10-7mol/L and 8.26×10-7mol/L, respectively. We also found that the PL-cys/GC electrode showed good electrocatalysis for RC and QC in PBS. |
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