| Since the discovery by Iijima in1991, carbon nanotubes (CNTs) open up a new era of nanomaterial technology and have caught the attention of universal research workers because carbon nanotubes (CNTs) possess especial structure (the hollow nano tube structure forming by the coaxial curly flake of the graphite piece),large specific surface area,strong conductivity,high mechanical strength, good metal properties,semiconductor characteristics and high chemical stability. In addition, due to the excellent mechanics and electrics characteristics of carbon nanotubes, they have huge potential application value in the field of preparing composite nanomaterial as the ideal added phase, besides the fascinating application prospect in the chemical analysis. In recent years, it is hot topics in the study of electroanalytical chemistry using carbon nanotubes as the added phase to preparing composite nanomaterals, and utilizing this composite nanomaterals to construct new modified electrodes. This study has important value for establishing new electroanalytical methods with high selectivity and high sensitivity. This paper progresses some preliminary researches and explorations aiming at the preparation of modified electrodes based on carbon nanotubes composite nanomaterals, and the application in electroanalytical chemistry, especially for solving the existing difficult problems of low selectivity, weak anti-interference ability in drug analysis and biological analysis. Specifically, in paper, the main innovation research work includes the following respects:1. Quantitative analysis of weak alkali medicines and weak acidic medicines using functionalized multi-walled carbon nanotubes/Nafion composite film-modified glassy carbon electrode (1) Functionalized multi-wall carbon nanotube/Nafion composite film-modified glassy carbon electrode (MWNTs/Nafion/GCE) was prepared. Several techniques, such as scanning electron microscopy (SEM) and electrochemistry were performed to characterize the MWNTs/Nafion/GCE. The electrochemical behavior of theophylline and caffeine was investigated using MWNTs/Nafion/GCE. In the electroanalytical determination of theophylline and caffeine, the prepared modified electrode can effectively improve some scientific problems, such as high overpotentia,slow electrode reaction and the low sensitivity, which always arise on traditional electrodes. A high sensitive electroanalytical method was established for the quantitative analysis of theophylline and caffeine.(2) MWNTs/Nafion/GCE demonstrates a significant electro-catalytic activity for the electrochemical oxidation of paeonol, and shows an excellent resistance capability toward the electrode passivation in the determination of paeonol. A high sensitive electroanalytical method was established for the quantitative analysis of paeonol, and multi-step mechanism for electrochemical oxidation of paeonol was inferred. In addition, the MWNTs/Nafion/GCE not only clearly enhanced the oxidation peak currents of AA and UA, but also avoided the overlapping of the anodic peak potential of AA and UA with a320mV separation. A high sensitive electro-analytical method was established for the simultaneous quantitative analysis of AA and UA.Studies have shown that MWNTs/Nafion/GCE can not only enhance the anodic peak currents of theophylline,caffeine,paeonol,AA and UA, but also decrease their anodic peak potentials. Experimental results demonstrated that MWNTs/Nafion/GCE not only can be used in the quantitative analysis of weak alkali medicine, but also suitable for the quantitative analysis of weak acid drugs.2. Preparation of methylene blue/functionalized multi-walled carbon nanotubes/Nafion composite film-modified electrode and its application for the simultaneous quantitative analysis of dopamine and uric acidUsing the adsorption of carbon nanotubes and the π-π conjugated electronic effects between carbon nanotubes and methylene blue, methylene blue/functionalized multi-walled carbon nanotubes nanocomposite with electrochemical features was prepared. Based on the two-component composite film modified electrode of MWNTs/Nafion/GCE, three-component composite film modified electrode of methylene blue/functionalized multi-walled carbon nanotubes/Nafion composite film-modified glassy carbon electrode (MB/MWNTs/Nafion/GCE) was fabricated. Several techniques, including UV-vis spectroscopy, scanning electron microscopy (SEM), atomic force microscope (AFM) and electrochemistry, were performed to characterize MB/MWNTs nanocomposite. Experiment found that, MB/MWNTs/Nafion/GCE can remarkably enhanced the oxidation peak currents of DA and UA, and decrease the anodic peak potential of DA. In addition, MB/MWNTs/Nafion/GCE avoided the overlapping of the anodic peaks of DA and UA and eliminated the interference of ascorbic acid (AA). Under the optimal conditions, the peak separation of AA and DA, DA and UA, was219and174mV, respectively. A high sensitive electro-analytical method was established for the simultaneous quantitative analysis of DA and UA.3. Preparation of yttrium hexacyanoferrate nanoparticle/functionalized multi-walled carbon nanotubes/Nafion composite film-modified electrode: Application to the quantitative analysis of L-cysteineIn this section, we have successfully prepared a new nano-material:yttrium hexacyanoferrate nanoparticle (YHCFNP). Several techniques, such as infrared spectroscopy, energy dispersive spectrometry (EDS), scanning electron microscopy (SEM) and electrochemistry, were used to characterize YHCFNPs. Based on the two-component composite film modified electrode of MWNTs/Nafion/GCE, three-component composite film modified electrode of YHCFNP/functionalized multi-walled carbon nanotubes/Nafion composite film-modified glassy carbon electrode (YHCFNP/MWNTs/Nafion/GCE) was fabricated. The electrochemical behavior of L-cysteine was investigated at the YHCFNP/MWNTs/Nafion/GCE. A series of experimental results showed that the oxidation peak current of L-cysteine could be intensively enhanced at the YHCFNP/MWNTs/Nafion/GCE. the YHCFNP/MWNTs/Nafion/GCE shows excellent characteristics, such as simple fabrication, wide linear range, fast response, high sensitivity and good resistance ability against interferences (such as ascorbic acid and other oxidizable amino acids). A high sensitive electro-analytical method was established for the quantitative analysis of L-cysteine.4. Preparation of gold nanoparticle/functionalized multi-walled carbon nanotubes/Nafion composite film-modified electrode:Application to the quantitative analysis of dopamineIn this section, we have successfully proposed a new method to prepare well-dispersed Au nanoparticles anchored on functionalized multi-wall carbon nanotubes nanocoposite (AuNP/MWNTs). SEM technique was used to determine the diameter of Au nanoparticle anchored on MWNTs. The diameter of Au nanoparticle is about10nm. Based on the two-component composite film modified electrode of MWNTs/Nafion/GCE, three-component composite film modified electrode of gold nanoparticle/functionalized multi-walled carbon nanotubes/Nafion composite film-modified glassy carbon electrode (AuNP/MWNTs/Nafion/GCE) was fabricated. AuNP/MWNTs/Nafion/GCE can remarkably enhance the oxidation peak current of DA and decrease the oxidation peak potential of DA. A high sensitive electro-analytical method was established for the quantitative analysis of DA.5. Preparation of gold nanoparticle/ethylenediamine/functionalized multi-walled carbon nanotubes/Nafion composite film-modified glassy carbon electrode:Application to the quantitative analysis of rutinIn this section, based on the single-layer composite film modified electrode of MWNTs/Nafion/GCE, through the dropping-electric aggregation-static adsorption method, three-layer composite film modified electrode of gold nanoparticle/ethylenediamine/functionalized multi-walled carbon nanotubes/Nafion composite film-modified glassy carbon electrode (AuNP/en/MWNTs/Nafion/GCE) was fabricated. The electrochemical behavior of rutin was studied on the AuNP/en/MWNTs/Nafion/GCE. The electrochemical parameters of rutin were calculated..The proposed method can also effectively avoid the interference of AA. A high sensitive electro-analytical method was established for the quantitative analysis of rutin. |
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