| In recent years, it is reported that the fast development for the application of biosensor in environmental science, food safety and clinical analysis, accompanied with the development of electrochemical chemistry. The single-walled carbon nanotubes(SWCNTs), as a special nanomaterials, played an important role for the fabrication of nonenzyme sensor. The single-walled carbon nanorubes(SWCNTs) have significant mechanical strength:high surface eara, excellent electron transmission and good chemical stability, especially after acid treatment of single-walled carbon nanotubes(SWCNTs), as to improve the electrical properties of the composite conductive filler, single-walled carbon nanotubes(SWCNTs) have become one of the quite popular problems in research area on each subject. Various metals have different effects on the electrode surface, and single-walled carbon nanotubes(SWCNTs) can improve and enlarge the metal film features. Therefore, the metal film/single-walled carbon nanotube nanocomposite is an ideal non-enzymatic electrochemical sensors. Such composite modified electrode is widely used, which can be applied to the glucose biosensor. And the diabetes is the third highest incidence of chronic diseases in the world with1million annual rate. Whether suffering from diabetes or not, mainly based on the patient’s blood glucose levels. Electrochemical sensors detect glucose levels as an effective means. The development of new electrode materials improved by surface modification, which promote the sensitivity and extend the life of the electrode, is an important aspect of researchers.In addition, the detection of heavy metals in the environment has become one of the hot pints in recent years, such as chromium. Chromium is one of the essential traceelements in human body, which is an important element to grow normally and regulating blood sugar. However, excessive intake of chromium in the body causes many injuries,especially hexavalent chromium. Hexavalent chromium compounds have severe local irritation and corrosion effects at high concentrations, while at low concentrations, which is a common carcinogen. So, study of the detection method of hexavalent chromium causes wide attention within the industry. Copper is also one of the body essential trace element in human body, copper,as a catalytic and cofactor,plays an important role in different physiological processes. However, excessive intake of copper in vivo or long-term exposure to copper dust will be poisoned, causing a number of neurological diseases. Due to the long-term overexpose copper to humans, copper has become an important pollutant in the environment. So looking for a new, rapid and sensitive method for the detection of copper ions is very important.This graduation thesis includes several sections, as follows:1.We make a brief overview for carbon nano-materials and metl film/single-walled carbon nanotube nanocomposite modified electrode, describing the significance of the detection of small molecules(glucose) in biological systems, and the traditional detection methods of glucose, the advantages of metal film/single-walled carbon nanotube nanocomposite electrodes, and the catalytic detection of glucose. We report that the hazards of heavy metal Cr (VI), the advantages of metal film/single-walled carbon nanotube nanocomposite electrodes which detect the trace Cr (Ⅵ), and the method of chromogenic agent to detect Cu (Ⅱ).2. The assembly, characterization modification of Ni-Ag/single-wall carbon nanotube composite nanowires nanocomposite electrode and outstanding features of electro-catalytic oxidation of glucose.This section describes the assembly of the composite electrode which was modified with Ni-Ag/single-wall carbon nanotube nanowires by seed-induced electrochemical synthesis way. A certain proportion of Ni-Ag bimetallic ions was intensive mixed with acidulated SWNTs, then this was modified with the surface of glassy carbon electrode. Ni-Ag ions form seed crystal on the electrode surface, then Ni-Ag solution can well-organized restore more quickly on the surface of single-wall carbon nanotubes to form a dense double-metal film during electrodeposition. Ni-Ag/single-wall carbon nanotube composite nanowire modified electrodes analysis glucose in alkaline solution with the advantages of high sensitivity and wide linear range. The electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), static water contact angle and voltammetry measurements of the modified electrode were made to characterize their properties. In Conclusion, Ni-Ag/single-wall carbon nanotube composite nanowire modified electrode has good hydrophilicity, conductivity, stability, reproducibility and interference.3. The preparation and characterization of Bi film wrapped single walled carbon nanotubes composite nanomaterials and its electrochemical detection of heavy metal Cr(VI).We report an improved Bi film wrapped single walled carbon nano-tubes modified glassy carbon electrode (Bi/SWNTs/GCE) as a highly sensitive platform for ultratrace Cr(VI) detection through catalytic adsorptive cathodic stripping voltammetry. The obtained Bi/SWNTs composite was well characterized with EIS), SEM, the static water contact angle and the voltammetric measurements. The results indicate the improvements in the quality of Bi film deposited on the surface of SWNTs such as faster speed of electron transfer, more uniform morphology, better hydrophilicity and higher stripping signal. Using DTPA as complexing ligand, the fabricated electrode displays a well-defined and highly sensitive peak for the reduction of Cr(Ⅲ)-DTPA complex at-1.06V(vs. Ag/AgCl) with a linear concentration range of0-25nM and a fairly low detection limit of0.036nM. No interference was found in the presence of coexisting ions, and good recoveries were achieved for the analysis of a river sample. In comparison to previous approaches using Bi film modified GCE, the newly designed electrode exhibits better reproducibility and repeatability toward aqueous detection of trace Cr(Ⅵ) and appears to be very promising as the basis of a highly sensitive and selective voltammetric procedure for Cr(Ⅵ) detection at trace level in real samples.4. Preparation of novel chromogenic agent for Cu (Ⅱ) ions and Spectrophotome-tric Method detect copper ions.This part report that we synthesized a novel Cu(Ⅱ)ion indicator which composed by reaction between cysteine and formaldehyde. This new indicator makes colorless Cu (Ⅱ) ions (low concentrations) turn blue. Then we use spectrophotometric method to detect copper ions. This new indicator has many advantages,such as low cost,being easy to be synthesized and detected, high speed and clarity of coloration and interference-free etc.It can be potentially used for direct analysis of other Cu(Ⅱ) contaminated real samples.4. Preparation of researching novel chromogenic agent for Cu (Ⅱ) ions and Spectrophotome-tric Method to detect copper ions.This part reports that we synthesized a novel Cu (Ⅱ) ion indicator which composed by reaction between cysteine and formaldehyde.Formaidehyde,itself, is a kind of commonly used adhesive, which can aggregate a lot of functional groups. The new indicator which is aggregated by Cys and CH2O, makes colorless Cu (Ⅱ) ions (low concentrations) turn blue. Then we use spectrophotometric method to detect the concentration of copper ions. The new indicator has many advantages, such as lowcost, easy to be synthesized and detected, high speed and clarity of coloration and interference-free etc, which, consequently, can be potentially used for direct analysis of other Cu(Ⅱ) contaminated real samples. |
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