Carbon nanotubes functionalizing doping

A stabilization effect is observed when the enzymes are immobilized onto magnetic nanoparticles [135, 175, 179]. As discuss also in the carbon nanotubes section, the stability can be further enhanced when covalent bond between the enzyme and the nanoparticles were used [177, 178, 197]. Moreover, the enzyme and the nanoparticles used, the functional groups doped on the surface of nanoparticles and the immobilization procedure are crucial factors which affect the activity and the structure of the enzyme upon immobilization [179, 181, 198]. 

Y. Ma, S.R. Ali, L. Wang, P.L. Chiu, R. Mendelsohn, and H. He, In situ fabrication of a water-soluble, self-doped polyaniline nanocomposite the unique role of DNA functionalized single-walled carbon nanotubes, J. Am. Chem. Soc., 128, 12064—12065 (2006). 

Ma, Y., All, S. R., Dodoo, A. S., and He, H. (2006]. Enhanced sensitivity for biosensors Multiple functions of DNA-wrapped single-walled carbon nanotubes In self-doped polyanlline nanocomposites, J Phys. Chem. B, 110, pp. 16359-16365. 

It is believed that some doped carbon nanotubes can provide the Pt catalyst with strong interaction. For example, highly dispersed Pt nanoparticles supported on surface of thiolation functional carbon nanotubes, such as S-doped CNTs (SH-CNTs), CNTs-CeHe-CHs-SH, CNTs-CONH-(CH2)2-SH, and CNTs—CONH—CeHe—SH, were explored. Furthermore, when some metal oxides such as NbTi02 and metal carbides were explored as the catalyst supports, strong interaction between catalyst and the support was also observed. ... 

Zhang, Y., Grebel, H., and Iqbal, Z. Polyethylene-imine functionalization of single wall carbon nanotubes for air-stable n-type doped coatings, unpublished data. 

It has also been seen that two nanomaterials can be functionalized with each other. One example is the synthesis of fullerene (C6o)-functionalized GNPs by the coupling of the fullerene molecules with peripheral amine moieties on the particle surface [66]. On the other hand, GNPs were selectively attached to chemically functionalized surface sites on nitrogen-doped carbon nanotubes. A cationic polyelectrolyte was adsorbed on the surface of the nanotubes by electrostatic interaction between carboxyl groups on the chemically oxidized nanotube surface and polyelectrolyte chains. 

Peng S, Cho K (2003) Ab initio study of doped carbon nanotube sensors. Nano Lett 3(4) 513—517 Penza M, Cassano G, Rossi R, Alvisi M, Rizzo A, Signore MA, Dikonimos T, Serra E, Gioigj R (2007) Enhancement of sensitivity in gas chemiresistors based on carbon nanotube surface functionalized with noble metal (Au, Pt) nanoclusters. Appl Phys Lett 90 173123... 

The following optimization of CNT-based gas sensors can be achieved through functionalization of carbon nanotubes (Qi et al. 2003 Bondavalli et al. 2009). For example. Shim et al. (2001) have shown that CNTFET functionalization by polyethyleneimine (PEI) considerably increases sensitivity to NO. The PEI coated CNTFETs showed a much higher sensitivity to NO compared to bare CNTFETs the CNTEET sensors could detect a concentration of 100 ppt and saturated at 3 ppb. This value of 100 ppt constitutes up to now the lowest gas concentration ever detected by a CNTFET gas sensor. This behavior is linked to the doping effect of high-density amines from the PEI molecules on carbon nanotubes. Information related to CNTs functionalization may also be found in Chap. 25 (Vol. 2) of this book. 

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