Solubility nanotubes

Singh et al. (2006) also used cycloaddition to prepare carbon nanotubes containing indium labeled diethylenetriamine pentaacetic acid (DTPA) derivatives (Figure 15.17). In the initial modification, a SWNT was derivatized to contain a primary amine at the end of a short PEG spacer. The resultant water-soluble nanotube then was reacted with DTPA to create a metal chelating group at the end of the chain. Subsequent loading of the chelate with mIn created a radionuclide-SWNT complex for in vivo biodistribution studies. 

Adronov A, Yao Z, Liu Y. Functionalization of single-walled carbon nanotubes with polymers New approaches to highly soluble nanotubes. In Abstracts of Papers, 227th ACS National Meeting 2004 Anaheim, CA. 

The preparation of carbon nanotube sheets, called carbon nanotuhe papers [60] and carbon nanotube films by physical adsorption [61] is already known. However, reports describing the preparation of thin films with high homogeneity from purified-carbon nanotubes dissolved or dispersed in solution are very limited. By utilizing soluble nanotubes, carbon nanotube ultrathin films can be formed. Ultrathin composite films of carbon nanotubes and amphiphiles are formed by means of the LB technique [62]. Krstic etal. described the formation of mono-layers of SWNTs and a surfactant on substrates with lithographically defined electrode arrays [63]. They measured the electrical transport of the electrodes. The... 

Since the discovery of SWNTs, they have been expected to become the building blocks of the next generation of functional nanomaterials. However, their strong cohesive property and poor solubility have restricted the use of SWNTs for fundamental and applied research fields. One method to overcome these problems is to make the SWNTs more soluble by wrapping them with polymers [31]. At the same time, the fabrication of high-performance carbon nanotube (CNT)-based composites is driven by the ability to create anisotropy at the molecular level to obtain appropriate functions. 

Feazell, R.P. et al. (2007) Soluble single-walled carbon nanotubes as longboat delivery systems for platinum(IV) anticancer drug design. Journal of the American Chemical Society, 129 (27), 8438-8439. 

Fig. 1.14 (A) Single-wall carbon nanotubes wrapped by glyco-conjugate polymer with bioactive sugars. (B) Modification of carboxyl-functionalized single-walled carbon nanotubes with biocompatible, water-soluble phosphorylcholine and sugar-based polymers. (A) adapted from [195] with permission from Elsevier, and (B) from [35] reproduced by permission of Wiley-VCH.

New applications of nitrile oxide 1,3-DC have been reported. Soluble, single-wall carbon nanotubes (SWNT) 32 functionalized with pentyl esters at the tips and pyridyl isoxazoline rings along the walls were prepared using pentyl ester-SWNT as dipolarophile. The complex... 

An important route to solubilization of carbon nanotubes is to functionalize their surface to form groups that are more soluble in the desired solvent environment. It has been shown that acid treatment of nanotube bundles, particularly with HC1 or HNO3 at elevated temperatures, opens up the aggregate structure, reduces nanotube length, and facilitates dispersion (An et al., 2004 Kordas et al., 2006). Nitric acid treatment oxidizes the nanotubes at the defect sites of the outer graphene sheet, especially at the open ends (Hirsch, 2002 Alvaro et al., 2004), and creates carbonyl, carboxyl, and hydroxyl groups, which aid in their solubility in polar solvents. 

Maehashi et al. (2007) used pyrene adsorption to make carbon nanotubes labeled with DNA aptamers and incorporated them into a field effect transistor constructed to produce a label-free biosensor. The biosensor could measure the concentration of IgE in samples down to 250 pM, as the antibody molecules bound to the aptamers on the nanotubes. Felekis and Tagmatarchis (2005) used a positively charged pyrene compound to prepare water-soluble SWNTs and then electrostatically adsorb porphyrin rings to study electron transfer interactions. Pyrene derivatives also have been used successfully to add a chromophore to carbon nanotubes using covalent coupling to an oxidized SWNT (Alvaro et al., 2004). In this case, the pyrene ring structure was not used to adsorb directly to the nanotube surface, but a side-chain functional group was used to link it covalently to modified SWNTs. 

Figure 15.15 An aldehyde derivative of pyrene can be used to couple a hydrophilic amino-PEG-carboxylate spacer by reductive amination. The resultant derivative then can be used to coat a carbon nanotube through pyrene ring adsorption and result in a water-soluble derivative containing terminal carboxylates for coupling amine-containing ligands.

Nakashima, N., Tomonari, Y., and Murakami, H. (2002) Water-soluble single-walled carbon nanotubes via noncovalent sidewall-functionalization with a pyrene-carrying ammonium ion. Chem. Lett. 31, 638-639. 

C. Hu, X. Chen, and S. Hu, Water-soluble single-walled carbon nanotubes films preparation, characterization and applications as electrochemical sensing films. J. Electroanal. Chem. 586, 77-85 (2006). 

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... 

In recent years, CNTs have been receiving considerable attention because of their potential use in biomedical applications. Solubility of CNTs in aqueous media is a fundamental prerequisite to increase their biocompatibility. For this purpose several methods of dispersion and solubilisation have been developed leading to chemically modified CNTs (see Paragraph 2). The modification of carbon nanotubes also provides multiple sites for the attachment of several kinds of molecules, making functionalised CNTs a promising alternative for the delivery of therapeutic compounds. 

Georgakilas V, Tagmatarchis N, Pantarotto D, Bianco A, Briand JP, Prato M (2002) Amino acid functionalisation of water soluble carbon nanotubes. Chem. Commun. 3050-3051. 

Liu Z, Sun X, Nakayama-Ratchford N, Dai H (2007a) Supramolecular Chemistry on Water-Soluble Carbon Nanotubes for Drug Loading and Delivery. ACS Nano 1 50-56. 

Tasis D, Tagmatarchis N, Georgakilas V, Prato M (2003) Soluble carbon nanotubes. Chem. Eur. J. 9 4001 1008. 

Yinghuai Z, Peng AT, Carpenter K, Maguire JA, Hosmane NS, Takagaki M (2005) Substituted carborane-appended water-soluble single-wall carbon nanotubes New approach to boron neutron capture therapy drug delivery. J. Am. Chem. Soc. 127 9875-9880. 

Sirotkin AK, Zarubaev W, Poznyiakova LN et al. (2006) Pristine fullerene C60 different water soluble forms - different mechanisms of biological action. Full Nanotubes Carb Nanostruct. 43 327-333. 

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