Single-walled carbon nanotube nanoparticles

Formation of single-walled carbon nanotubes (SWNTs) was found to be catalyzed by metal nanoparticles [207]. Wang et al. [114] investigated bimetallic catalysts such as FeRu and FePt in the size range of 0.5-3 nm for the efficient growth of SWNTs on flat surfaces. When compared with single-component catalysts such as Fe, Ru, and Pt of similar size, bimetallic catalysts Fe/Ru and Fe/Pt produced at least 200% more SWNTs [114]. 

Jin, H. et al. (2009) Size-dependent cellular uptake and expulsion of single-walled carbon nanotubes single particletracking and a generic uptake model for nanoparticles. ACS Nano, 3 (1), 149-158. 

Moisala, A. Nasibulin, A. G. Kauppinen, E. I. 2003. The role of metal nanoparticles in the catalytic production of single-walled carbon nanotubes—a review. J. Phys. Condens. Matter 15 S3011-3035. 

Choi JH, Nguyen FT, Barone PW, Heller DA, Moll AE, Patel D, Boppart SA, Strano MS (2007) Multimodal biomedical imaging with asymmetric single-walled carbon nanotube/iron oxide nanoparticle complexes. Nano Lett. 7 861-867. 

Tan, Z., H. Abe, and S. Ohara, Ordered deposition of Pd nanoparticles on sodium dodecyl sulfate-functionalized single-walled carbon nanotubes. Journal of Materials Chemistry, 2011. 21(32) p. 12008-12014. 

Ozawa, H., et al., Supramolecular hybrid of gold nanoparticles and semiconducting single-walled carbon nanotubes wrapped by a porphyrin-fluorene copolymer. Journal of the American Chemical Society, 2011.133(37) p. 14771-14777. 

Sun, J., et al., Single-walled carbon nanotubes coated with titania nanoparticles. Carbon, 2004. 42(4) p. 895-899. 

Mubeen, S., et al., Palladium nanoparticles decorated single-walled carbon nanotube hydrogen sensor. The Journal of Physical Chemistry C, 2007.111(17) p. 6321-6327. 

Li, X. Jia, Y. Cao, A., Tailored single-walled carbon nanotube-Cds nanoparticle hybrids for tunable optoelectronic devices. ACS Nano 2009, 4, 506-512. 

G. Cheng and T. Guo, Surface segregation in Ni/Co bimetallic nanoparticles produced in single-walled carbon nanotube synthesis, J. Phys. Chem. B 106, 5833-5839 (2002). 

Chromatographic approaches have been also used to separate nanoparticles from samples coupled to different detectors, such as ICP-MS, MS, DLS. The best known technique for size separation is size exclusion chromatography (SEC). A size exclusion column is packed with porous beads, as the stationary phase, which retain particles, depending on their size and shape. This method has been applied to the size characterization of quantum dots, single-walled carbon nanotubes, and polystyrene nanoparticles [168, 169]. Another approach is hydro-dynamic chromatography (HDC), which separates particles based on their hydro-dynamic radius. HDC has been connected to the most common UV-Vis detector for the size characterization of nanoparticles, colloidal suspensions, and biomolecules [170-172]. 

Ni(CO)4 is the sole binary carbonyl complex of the elements of group 10 that is stable (Table 8.1). However, very few studies in which Ni(CO)4 is used in the preparation of catalysts have been reported [43]. This is probably due to the difficulty of manipulation of Ni(CO)4 and its very high toxicity. However, surface Ni(CO)4 species have been identified after the interaction of CO with highly dispersed supported nickel catalysts prepared by other routes [44]. Recent interest in the use of Ni(CO)4 has focused on the controlled production of nickel nanoparticles for specific purposes, such as in automotive converters [45]. The use of nickel tetracarbonyl as an agent for the nucleation process in the growth of single-wall carbon nanotubes has also been reported [46]. 

Metallic nanoparticles and single-walled carbon nanotubes (SWCNTs) exhibit nanoscale dimensions comparable with the dimensions of redox proteins. This enables the construction of NP-enzyme or SWCNT-enzyme hybrids that combine the unique conductivity features of the nanoelements with the biocatalytic redox properties of the enzymes, to yield wired bioelectrocatalyts with large electrode surface areas. Indeed, substantial advances in nanobiotechnology were achieved by the integration of redox enzymes with nanoelements and the use of the hybrid systems in different bioelectronic devices.35... 

A similar methodology has been extended by Keren et al. to non-invasive imaging of the mouse, using SERS nanoparticles that had accumulated in the liver [33]. An example is shown in Fig. 5.5. This group also demonstrated that single-walled carbon nanotubes, which have an intense Raman band at 1, 593 cm-1, can be functionalized and used for non-invasive imaging. 

Nanomaterials can also be applied to glucose biosensors to enhance the properties of the sensors and, therefore, can lead to smaller sensors with higher signal outputs. Carbon nanotubes have been incorporated in previously developed sensors and seen to increase the peak currents observed by threefold.89 Platinum nanoparticles and single-wall carbon nanotubes have been used in combination to increase sensitivity and stability of the sensor.90,91 CdS quantum dots have also been shown to improve electron transfer from glucose oxidase to the electrode.92,93 Yamato et al. dispersed palladium particles in a polypyrrole/sulfated poly(beta-hydro-xyethers) and obtained an electrode response at 400 mV, compared to 650 mV, at a conventional platinum electrode.94... 

Fluorous chemistry, involving the use of a fluorous label for the functionalization of a substrate and a fluorous solvent for extraction of the functionalized substrate, is shown to be effective in solubilizing gold and CdSe nanoparticles in a fluorous medium, through phase transfer from an aqueous or a hydrocarbon medium. While these nanoparticles were functionalized with a fluorous thiol, single-walled carbon nanotubes and ZnO nanorods could be solubilized in a fluorous medium by reacting them with a fluorous amine. Fluorous chemistry enables the solubilization of the nanostructures in the most nonpolar liquid medium possible. 

In conclusion, we have successfully demonstrated that, by using a fluorous label and a fluorous solvent, we can affect the phase transfer of gold and CdSe nanoparticles from an aqueous or hydrocarbon medium to the fluorous phase. Single-walled carbon nanotubes and ZnO nanorods can be solubilized in a fluorous solvent after interaction with a fluorous amine. Phase transfer of the nanostructures to a fluorous solvent represents solubilization in a highly nonpolar solvent, accompanied by purification. The high nonpolarity of the fluorocarbon makes it possible to study the optical and other properties of nanostructures in a medium of very low refractive index. Since the fluorocarbon extracts only the species attached to the fluorous label, the process enables one to obtain solely one product in the pure state. We believe that fluorous chemistry may have practical utility in carrying out studies of nanostructures. 

The resolution of SEMs is now suitable for nano-materials characterization. High resolution SEM is a powerful instrument for imaging fine structures of materials and nanoparticles fabricated by nanotechnology. In lens SE, BSE modes, and STEM mode are often performed to check the structure of CNT growths or CNT as delivered by commercial producers, and sometimes coupled with TEM. Even the single-walled carbon nanotubes can easily be observed by HR-SEM (see Figure 3.13). The STEM mode can also be used for free CNT observation (75). 

A brand new area should conclusively be mentioned, that of the PP-nanocomposites made of single-walled carbon nanotubes [157] or silica nanoparticles [158] which were reported to facilitate the growth of the -crystalline structure. However, no published data support their supposed outstanding performance. 

Chu H, Wang J, Ding L, Yuan D, Zhang Y, Liu J, Li Y (2009) Decoration of gold nanoparticles on surface-grown single-walled carbon nanotubes for detection of every nanotube by surface-enhanced Raman spectroscopy. J Am Chem Soc 131 14310-14316... 

Inorganic semiconductor nanoparticles have also been implemented as electron acceptors. For example, CdSe, CnInSc2 and PbS have been of interest becanse they absorb in the visible and can extend the blend absorption ont to the near infrared (Huynh et al, 2002 Sun et al, 2003), as discussed in Section 7.4.4. In one study, CdSe nanoparticles were combined with single-walled carbon nanotubes for improved light harvesting and as material variations for BHJ devices (Robel et al, 2005). 

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