The Problem of Purifying Single‐Walled Carbon Nanotubes

Vivekchand, S. R. C.; Jayakanth, R.; Govindaraj, A.; Rao, C. N. R.

doi:10.1002/smll.200500092

Cited by 64 publications

(54 citation statements)

References 18 publications

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“…SWNTs were prepared by DC arc-discharge process. After preparation, the SWNTs were treated with HCl and heated in H 2 several times to remove the metal nanoparticles and amorphous carbon (16). ND with phase purity higher than 98% and an average particle size of around 5 nm was purchased from Tokyo Diamond Tools.…”

Section: Methodsmentioning

confidence: 99%

Extraordinary synergy in the mechanical properties of polymer matrix composites reinforced with 2 nanocarbons

Prasad

Das²,

Maitra³

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

273

190

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One of the applications of nanomaterials is as reinforcements in composites, wherein small additions of nanomaterials lead to large enhancements in mechanical properties. There have been extensive studies in the literature on composites where a polymer matrix is reinforced by a single nanomaterial such as carbon nanotubes. In this article, we examine the significant synergistic effects observed when 2 different types of nanocarbons are incorporated in a polymer matrix. Thus, binary combinations of nanodiamond, fewlayer graphene, and single-walled nanotubes have been used to reinforce polyvinyl alcohol. The mechanical properties of the resulting composites, evaluated by the nanoindentation technique, show extraordinary synergy, improving the stiffness and hardness by as much as 400% compared to those obtained with single nanocarbon reinforcements. These results suggest a way of designing advanced materials with extraordinary mechanical properties by incorporating small amounts of 2 nanomaterials such as graphene plus nanodiamond or nanodiamond plus carbon nanotube.binary combinations ͉ nanoindentation technique ͉ polyvinyl alcohol ͉ synergistic effects A mong the many unique attributes of nanomaterials, especially noteworthy are their large surface to volume ratios and outstanding mechanical properties. These properties offer venues for exciting areas of research as well as for technological innovations. Thus, an important use of nanomaterials is in reinforcing polymer matrices taking advantage of the ultra-high stiffness and hardness exhibited by them. Recent research has shown that small additions (up to Ϸ1 wt%) of certain nanomaterials such as carbon nanaotubes enhance the mechanical properties markedly, sometimes by as much as 100% (1-8). Although the precise mechanism responsible for this dramatic enhancement is not entirely understood, it is generally believed that molecular level interactions between the nanomaterials and polymer matrices play a major role. The large interface area available for such interactions clearly hold the key for the dramatic enhancement in mechanical properties.Of the variety of nanomaterials synthesized and characterized in recent years, nanocarbons of different dimentionalities are of particular interest, as exemplified by nanodiamond, nanotubes and graphene with dimensionalities of 0, 1, and 2, respectively (1-3). Extensive research has been carried out on the mechanical properties of composites made of polymer matrices with 1 of the nanocarbons as the reinforcement phase (1-8). We would expect the nature of interaction of the nanocarbon constituent with the matrix to vary with the dimensionality. For example, carbon nanotubes added to a polymer can interact over the length of the polymer chain whereas a nanodiamond particle can interact only at a point, possibly at the ends of a polymer chain. While each of the nanocarbons improves the mechanical properties of the polymer matrix, we felt intuitively that incorporation of 2 nanocarbons could lead to synergistic effects in the m...

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Section: Methodsmentioning

confidence: 99%

Extraordinary synergy in the mechanical properties of polymer matrix composites reinforced with 2 nanocarbons

Prasad

Das²,

Maitra³

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

273

190

View full text Add to dashboard Cite

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“…The nanotubes are characterized by the thermogravimetric analysis, transmission electron microscopy (TEM), Raman spectroscopy [RS] and near infrared spectroscopy (NIR) [36]. The average diameter of the nanotubes was about 1.4 nm, the length being a few microns.…”

Section: Methodsmentioning

confidence: 99%

Binding of nucleobases with single-walled carbon nanotubes: Theory and experiment

Das

Sood

Maiti

et al. 2008

Chemical Physics Letters

102

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We have calculated the binding energy of various nucleobases (guanine (G), adenine (A), thymine (T) and cytosine (C)) with (5,5) single-walled carbon nanotubes (SWNTs) using ab-initio HartreFock method (HF) together with force field calculations. The gas phase binding energies follow the sequence G > A > T > C. We show that main contribution to binding energy comes from van-der Wall (vdW) interaction between nanotube and nucleobases. We compare these results with the interaction of nucleobases with graphene. We show that the binding energy of bases with SWNTs is much lower than the graphene but the sequence remains same. When we include the effect of solvation energy (Poisson-Boltzman (PB) solver at HF level), the binding energy follow the sequence G > T > A > C >, which explains the experiment [16] that oligonucleotides made of thymine bases are more effective in dispersing the SWNT in aqueous solution as compared to poly (A) and poly (C). We also demonstrate experimentally that there is differential binding affinity of nucleobases with the single-walled carbon nanotubes (SWNTs) by directly measuring the binding strength using isothermal titration (micro) calorimetry. The binding sequence of the nucleobases varies as thymine (T) > adenine (A) > cytosine (C), in agreement with our calculation.

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“…64 The cytotoxicity of these metals is well known and well documented. It was demonstrated that rat macrophages and human A549 lung cells, when exposed to unpurified CNTs, released reactive oxygen species intracellularly due to cell oxidative stress.…”

Section: Nanotube Impuritiesmentioning

confidence: 99%

“…CNTs are capable of forming well-dispersed suspensions in aqueous solutions after oxidation in acid solutions, mainly due to the formation of carboxyl groups. 64 Even higher degrees of aqueous solubility can be attained by functionalizing the sidewalls with hydrophilic moieties, such as polymers. Studies on Chinese hamster ovary cells and Jurkat human T-lymphoma cells using glycopolymer-coated SWNTs and unfunctionalized SWNTs have demonstrated lower cytotoxicity for the functionalized SWNTs.…”

mentioning

confidence: 99%

Stealth nanotubes: strategies of shielding carbon nanotubes to evade opsonization and improve biodistribution

Kotagiri¹,

Kim²

2014

IJN

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Carbon nanotubes (CNTs) have recently been in the limelight for their potential role in disease diagnostics and therapeutics, as well as in tissue engineering. Before these medical applications can be realized, there is a need to address issues like opsonization, phagocytosis by macrophages, and sequestration to the liver and spleen for eventual elimination from the body; along with equally important issues such as aqueous solubility, dispersion, biocompatibility, and biofunctionalization. CNTs have not been shown to be able to evade such biological obstacles, which include their nonspecific attachments to cells and other biological components in the bloodstream, before reaching target tissues and cells in vivo. This will eventually determine their longevity in circulation and clearance rate from the body. This review article discusses the current status, challenges, practical strategies, and implementations of coating CNTs with biocompatible and opsonin-resistant moieties, rendering CNTs transparent to opsonins and deceiving the innate immune response to make believe that the CNTs are not foreign. A holistic approach to the development of such “stealth” CNTs is presented, which encompasses not only several biophysicochemical factors that are not limited to surface treatment of CNTs, but also extraneous biological factors such as the protein corona formation that inevitably controls the in vivo fate of the particles. This review also discusses the present and potential applications, along with the future directions, of CNTs and their hybrid-based nanotheranostic agents for multiplex, multimodal molecular imaging and therapy, as well as in other applications, such as drug delivery and tissue engineering.

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The Problem of Purifying Single‐Walled Carbon Nanotubes

Cited by 64 publications

References 18 publications

Extraordinary synergy in the mechanical properties of polymer matrix composites reinforced with 2 nanocarbons

Extraordinary synergy in the mechanical properties of polymer matrix composites reinforced with 2 nanocarbons

Binding of nucleobases with single-walled carbon nanotubes: Theory and experiment

Stealth nanotubes: strategies of shielding carbon nanotubes to evade opsonization and improve biodistribution

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