Carbon nanotube MWNT hybrids

The use of electrodes modified with immobilized redox-active molecules provides a simple methodology by which to study the ultrathin film electrochemistry of water-insoluble redox-active molecules, encouraging the application of such techniques to biomimetic membranes in aqueous media. It is of interest to use monolayer and LB films of enzymes, proteins, and antibodies as biosensors or biomolecular switches because of their high sensitivity for their substrates and antigens, respectively. The formation of thin fullerene films including fullerene-lipid hybrid and fullerene-lipid composite bilayer membranes is of interest both from a fundamental and practical application point of view. Multiwalled carbon nanotubes (MWNTs) and single-walled carbon nanotubes (SWNTs) are novel nanomaterials that have remarkable electronic, mechanical, and thermal properties, and specific functions. Soluble carbon nanotubes in aqueous and organic systems are of interest since their study allows the... 

A label-free electrochemical DNA biosensor based on 4,4 -diaminoazobenzene (4,4 -DAAB) and multiwalled carbon nanotube (MWNT)-modified GCE for short DNA sequences related to HBV hybridization detection was presented by Li et al. [92]. DPV was used to investigate hybridization event. The decrease in the peak ciurent of 4,4 -DAAB was observed on hybridization of probe with the target. This electrochemical approach was sequence specific as indicated by the control experiments, in which no peak eurrent change was observed when a non complementary DNA sequence was used. Numerous factors affecting the target hybridization were optimized to maximize the sensitivity. Under optimal conditions, this sensor showed a good calibration range between 7.94 xlO M and 1.58 xlO M, with HBV DNA sequence deteetion limit of 1.1 xlO M. 

Carbon nanotubes have been decorated with metal nanoparticies of Au, Ag, Pt, Pd and Co employing different procedures such as the click reaction [107], microwave treatment [106], electroless plating [108] and laser irradiation of mixtures of the individual components [109]. Pt-carbon nanotube hybrids have been used as catalysts for the conversion of nitrobenzene to aniline [110]. Tessonier et al. report that MWNTs covered with Pd nanoparticies on the interior walls can be employed for... 

Carbon nanotubes are shells of sp -hybridized carbon atoms that form a hexagonal network within a tubular motif closed at the ends by hemispherical endcaps. Manufactured as single-walled (SWNTs) or multi-walled (MWNTs) systems with different diameters and lengths, each type of CN has different properties. 

Figure 4 (A) AFM images (a) MWNTs/CoTMPyP/RCI film assembled on GC electrode (before electrochemical reduction) (b) MWNTs/CoTMPyP/R hybrid film (after electrochemical reduction at - 0.7 V in N2-saturated 0.1 mol I KCI solution). (B) XPS data of MWNTs/CoTMPyP film on GC surface (cun/es (a) and (b)) and MWNTs/CoTMPyP/RCii" film in the R (4f) region before (cun/e (c)) and after (cun/e (d)) electrochemical reduction. (Qu JY, Shen Y, Qu XH, and Dong SJ (2004) Preparation of hybrid thin film modified carbon nanotubes on glassy carbon electrode and its electrocatalysis for oxygen reduction. Chemical Communications 2004 34-35 reproduced by permission of The Royal Society of Chemistry.)...

A performant reagentless ECL system for H2O2 detection based on electrop-olymerized luminol on pre-treated screen-printed electrodes was developed [64]. An ECL biosensor based on carboxylic acid-functionaUzed multi-walled carbon nanotubes (CCX)H-F-MWNT) and Au nanoparticles [65] and immobilization in sol-gel hybrid material was fabricated for sensing the efficiency of ethanol. The intensity of ECL increased linearly with ethanol concentration from 2.5 x 10 5.0 X 10 M and detection limit was 1.0 x 10 M [66]. 

Chitosan-Pmssian blue-multiwall carbon nanotube-hollow gold nanosphere (Chit-PB-MWNT-HGN) films were fabricated to be employed in AChE biosensorsIncorporating MWNTs and HGNs into a Chit-PB hybrid film promoted the electron transfer reaction, enhanced the electrochemical response, and improved the microarchitecture of the electrode surface. Based on the inhibition of the AChE activity by the pesticides malathion, chlorpyrifos, monocrotophos, and carbofuran as model compounds, the biosensor showed a wide dynamic range, low detection limit, good reproducibility, and high stability. Moreover, the AChE/Chit-PB-MWNT-HGN/Au biosensor could also be used for the direct analysis of a practical samples, which would be a new promising tool for pesticide analysis. 

Two case studies are presented in which polymer nanotube composites are proposed as replacements for conventional materials. We evaluate the technical and economic feasibility of using them as smart materials for strain gauges thus, exploiting their electrical properties, and as structural materials for aircraft panels bringing into play their mechanical properties. Our analysis shows that as new strain gauge materials, polymer nanotube composites offer many advantages. As a possible replacement for aluminum in an aircraft panel, it is found that a hybrid composite of (Epoxy 33% carbon fabric + 30% carbon fibers + 3% CVD-MWNT) is an attractive candidate. 

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