Functionalized SWNTs

Phenyl-functionalized SWNTs HiPCO ([Pg.199]

RO- 33. Carboxylic acid-functionalized SWNTs bearing series of galactosylated or mannosylated mono-, di-, or trivalent dendrons.262... 

The acid reflux procedure was first described by Rinzler el al. [28], in which raw nanotube materials are refluxed in nitric acid to oxidize the metals and carbon impurities. Acid-treated CNTs are considered to have carboxylic acid groups at the tube ends and, possibly, at defects on the side walls. The functionalized SWNTs have considerably different properties from those of the pristine tubes. 

FIGURE 15.22 Raman spectra of NH3 and ND3 functionalized SWNTs by glow-discharge. (Reprinted with permission from [140]. Copyright (2004) American Chemical Society.)... 

The same group reported the simultaneous radiolabeling (with DOTA-anchored 4Cu) and fluorescence studies, coupled with biodistribution in vivo and in vitro (92). It is believed that appropriately functionalized SWNTs can efficiently reach tumor tissues in mice with no apparent toxicity (159). Furthermore, water-solubilised carbon nanotubes are nontoxic when taken up by cells even in high concentration (92). These studies have been complemented by the recent PET imaging of water-soluble 86Y labelled carbon nanotubes in vivo (mice) (160,161), to explore the potential usefulness of carbon nanocarriers as scaffolds for drug delivery. The tissue biodistribution and pharmacokinetics of model DOTA functionalized nanotubes have been explored in vivo (mouse model). MicroPET images indicated accumulation of activity mainly in the kidney, liver, spleen, and to a much less... 

Fig. 34. Model of a functionalised (internally or externally) SWNT, which may be closed, open and/or corked reversibly or permanently after filling. Potentially the inner cavity may be filled with a (radio)-imaging agent (for PET/SPECT and/or MRI) or a (radio)therapeutic agent. Such functionalized SWNTs may conceivably act as probe prototype for multimodal imaging/therapy and targeted drug delivery (155).

COOH)2, swnt- phenyl-S03Na, underivi-tized SWNT stabilized in 1% Pluronic F108 (3 pg/ml-30 mg/ml) (HDF) cytotoxic as the degree of sidewall functionalization increases The sidewall functionalized SWNT samples are substantially less cytotoxic than surfactant stabilized SWNTs (2006)... 

Guldi DM, Marcaccio M, Paolucci D et al (2003) Single-wall carbon nanotube-ferrocene nanohybrids observing intramolecular electron transfer in functionalized SWNTs. Angew Chem Int Ed 42 4206-4209... 

According to an earlier report from the same research group, galactose-functionalized SWNTs (Gal-SWNT) were used to bind and agglutinate pathogenic E. coli 0157 H7 cells.35 The binding required no divalent cations and was specific to... 

Figure 6.2 The Ca2+-mediated aggregation of anthrax spores with sugar functionalized SWNTs (a) a schematic illustration (b) SEM image (scale bar = 500 nm) and (c) optical image (scale bar = 20 p.m).u (Reprinted with permission from H. Wang et al., J. Am. Chem. Soc. 2006, 128, 13364—13365.

A representative example of indirect imaging with SWNTs labeled with fluorescent molecules was illuminated by Dai and coworkers.102 They solubilized as-produced SWNTs via sonication with fluorescein-modified poly (ethylene glycol) (Fluor-PEG, 114 PEG units). The absorption maximum of the nanotube-attached Fluor-PEG was red shifted 3 nm from that of free fluorescein, and the fluorescence intensity was quenched about 67% in phosphate buffer solution (pH 7.4). In the bioevaluation with BT474 breast cancer cells, substantial intracellular fluorescence was observed, suggesting cellular uptake of the Fluor-PEG-functionalized SWNTs.102... 

In general, on chemical modification carbon nanotubes exhibit much less toxicity or nontoxicity to living cell lines that have been investigated so far.117,118 For instance, Dumortier et al. conducted an in vitro cell uptake study of the functionalized SWNTs with B and T lymphocytes and macrophages.117 Two types of functionalized SWNTs were used, one prepared via 1,3-dipolar cycloaddition reaction and the other obtained through oxidation/amidation treatment. Both types of the functionalized nanotubes were rapidly taken up by lymphocytes and macrophages without affecting the overall... 

Schipper et al. also conducted a pilot toxicologic study of the covalently and noncovalently PEG-functionalized SWNTs in mice.123 Their results suggested that the functionalized SWNTs persisted within liver and spleen macrophages for four months without apparent toxicity.123... 

Figure 6.15 (Top) A scheme of noncovalently functionalized SWNTs by various PEGylated phospholipids, and SWNTs in mice tissues probed by ex vivo Raman spectroscopy after injection into mice, (a) Biodistribution of SWNT-/-2kPEG, SWNT-/-5kPEG, and SWNT-br-7kPEG, respectively, at 1 day postinjection measured by Raman spectroscopy. The SWNT concentrations in most organs are below detection hmit. (b) and (c) Evolution of the concentrations of SWNTs retained in the liver and spleen of mice over a period of 3 months. Compared with SWNT-/-2kPEG, much lower concentrations of retained SWNTs in the liver and spleen were observed for SWNT-/-5kPEG and SWNT-br-7kPEG.

More recently, Liu et al. (47), compared OH- covalently functionalized SWNTs to SDS stabilized SWNTs. The authors used Raman spectroscopy to understand why the improvements of the Young s modulus and strength are greater for covalently functionalized nanotubes. The Raman shift was plotted versus the tensile strain in the two composites PVA/OH-SWNTs and PVA/ SDS dispersed SWNTs, in the elastic regime (for strain values below 1.2%). The shift is linear in this regime, and a larger slope is measured... 

Polymeric carbon nanocomposites are often functionalized with matrix polymers. An example is the functionalization of SWNTs and MWNTs with poly(vinyl alcohol) using a carbodiimide mediated esterification reaction. Also, poly(ethylene-co-vinyl alcohol) is used for this purpose to produce DMSO soluble functionalized SWNTs. In a similar manner poly(m-aminobenzene sulfonic acid) is covalently bonded to SWNTs to form water soluble graft copolymers. ... 

ODA functionalized SWNTs has indicated that the affinity of the amine groups to the nanotubes is significant. Hence, the dissolution of ODA functionalized SWNTs is not entirely due to the covalent grafting. 

Mayo JD, Behai S, Adronov A (2009) Phase separation of polymer-functionalized SWNTs within a PMMA/Polystyrene blends. J Poiym Sci Poiym Chem 47 450-458 Cou JY, Lensch-Falk JL, Hemesath ER, Lauhon LJ (2009) Vanadium oxide nanowire Phase and orientation analyzed by Raman spectroscopy. J Appl Phys 105 034310-1-034310-6 Wang ZL (2004) Functional oxides nanobelts-materials, properties and potential applications in nanosystems and biotechnology. Annu Rev Phys Chem 55 159-196 Bliznyuk VN, Singamaneni S (2009) Polymer carbon nanotube composites. Encyclopedia of nanoscience and nanotechnology, (2012), ASP, Ed. H. S. Nalwa... 

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