Composites Of Carbon Nanotubes Dendrimer And Its Properties

Carbon nanotubes has particular machanical, chemical andelectrical properties. It can encourage electron transfer when carbonnanotubes are modified on electron surface. Poly(amidoamine)(PAMAM)dendrimer has been one of the hotspots resent years. PAMAM is a kind ofmacromolecule which has many branches and three-dimensional sphericalstructure. One of the foremost characteristic of PAMAM is a lot of definitenumbered terminal groups which have a critical impact on physical andchemical proterties of molecule. Moreover, the various functional groups cancombine on the dendrimer surface to expand its function. In this paper, wecombined multiwalled carbon nanotubes(MWNT) and PAMAM and studiedtheir optical property and electrochemical application.Ⅰ. Study of electrochemical DNA biosensor based on PAMAM/Ag+composite and MWNTThis study describes a new type of electrochemical DNA biosensor.G4.5/Ag+ composite was synthesized by complexing Ag+ with G4.5 PAMAMdendrimer interior amino group, and then the composite was marked tossDNA to be DNA probe. In this paper, the complexation between G4.5 andAg+ at several different acidity was charactered by UV-visible spectra.Moreover, UV-visible spectra showed that the preparation of the G4.5/Ag+composite labeled ssDNA probe was successful. Ag+ could close to electrodesurface by hybridization between the DNA probe and the other ssDNAbonding on the MWNT-modified GC electrode. After that the Ag+ would bedetermined by ASV. We also discussed the parameters of ASV such likeconcentration electrie potential and concentration time. Experimental resultsindicated that The DNA electrochemical sensor had good specificity and highsensitivity.And it is expected to be applied in the bioanlysis of DNA. Ⅱ. Determination of nitrite based on PAMAM-modified MWNT for electro-catalytic oxidation of nitriteThis study describes a simple and reliable method for the electrochemicaldetermination of nitrite based on PAMAM-modified MWNT. There are a lot offunctional groups on PAMAM dendrimers surface. Amine-terminated PAMAM(generation 4.0, G4) were covalently attached onto MWNT-modified glasscarbon (GC) electrodes (written as G4/MWNT/GC) and which were used forthe electrochemical determination of nitrite. The studies show that theG4/MWNT-modified electrodes demonstrated significantly enhancedelectrochemical activity towards nitrite oxidation. Some influence factors suchlike the generation of the PAMAM , base solution and coupling agent wereinvestigated. Chronoamperometry studies reveal that the amperometricresponse is rapid, stable, and offers a linear dependence over a wide range ofnitrite concentrations from 5μM to 1.5μM. The proposed method can be usedfor the continuous monitoring of nitrite in real samples. The electrochemicalproperties of the G4/MWNT nanocomposites are reasonably envisaged to bepromising for providing a nanostructured platform in the development ofelectrochemical sensors or biosensors.Ⅲ. The spectral analysis of PAMAM/metal ion and PAMAM/MWNTIn this paper, we combined three PAMAM (G2, G4, G4.5) with metal ionsand MWNT and studied the fluorescence property of them in differentconditions like pH value, mixture ratio and concentration. After combindingwith metal ions or MWNT, the fluorescence of G4 or G4.5 quenched at thelarger concentration but enhanced at the low concentration. Different from G4and G4.5, G2 quenched all the time after combining. It should be the natureproperty of the PAMAM because the regular pattern is irrelevant to the kind ofmetal ion. In this paper, we tried explaining the mechanism of the phenomenon. We supposed catalytic oxidation of amino induced by metal ionsand MWNT was a possible reason.