Temperature effects on the nitric acid oxidation of industrial grade multiwalled carbon nanotubes

Andrade, N. F.; Martinez, Diego Stéfani T.; Paula, Amauri J.; Silveira, J. V.; Alves, Oswaldo Luiz; Filho, A. G. Souza

doi:10.1007/s11051-013-1761-8

Cited by 40 publications

(35 citation statements)

References 49 publications

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“…It is currently know that the early decomposition of preserved graphitic sheets in CNT thermograms can be generally associated with the total degree of oxidation of a sample 47 .…”

Section: Nanocarbons Morphological and Structural Characterization Tmentioning

confidence: 99%

Mechanisms of Colloidal Stabilization of Oxidized Nanocarbons in the Presence of Polymers: Obtaining Highly Stable Colloids in Physiological Media

Padovani¹,

Petry²,

Holanda³

et al. 2015

J. Phys. Chem. C

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There are successful protocols for dispersing carbon nanotubes and graphene oxide in physiological media by using biocompatible polymers, which enable their use in nanomedicine. However, there is not a clear understanding regarding the mechanisms of the colloidal stabilization manifested (i.e., electric, steric or electrosteric or through depletion forces). Here we show that the manifestation of a particular mechanism of stabilization for oxidized carbon nanotubes (CNTs) and graphene oxide (GO) in the presence of Pluronic F-127 (PF127) and short-and long-chain polyethylene glycol (PEG 1,500 or 35,000 respectively) depends on a proper matching between the nanocarbon morphology and the polymer chain length, chemical structure and concentration. The high aspect ratio one dimensional morphology of CNTs enables an initial steric and electrosteric stabilization through the nanotube wrapping (i.e., adsorption) by PF127 present in low concentrations (<0.1%). Depletion stabilization for CNTs manifests when PF127 is present in high concentrations (≥1.0%), thus enabling the formation of highly stable CNT colloids even in a 0.9% NaCl saline solution. This depletion stabilization depends little on the CNT structure (i.e., single-or multi-wall), surface charge (i.e., zeta potential), oxidation and carboxylation degree or the nanotube length. On the other hand, large-sized sheets of GO could be colloidally stabilized in NaCl 0.9% only in the presence of PEG 35,000 through repulsive depletion forces, whose manifestation occurs with a polymer concentration threshold of 5.0 wt%. Comparatively, in a physiological saline solution, PF127 is able to colloidally stabilize CNTs to a much large extent than PEG 35,000 stabilizes the large GO sheets.

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“…It is currently know that the early decomposition of preserved graphitic sheets in CNT thermograms can be generally associated with the total degree of oxidation of a sample 47 .…”

Section: Nanocarbons Morphological and Structural Characterization Tmentioning

confidence: 99%

Mechanisms of Colloidal Stabilization of Oxidized Nanocarbons in the Presence of Polymers: Obtaining Highly Stable Colloids in Physiological Media

Padovani¹,

Petry²,

Holanda³

et al. 2015

J. Phys. Chem. C

Self Cite

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“…Quantitative assessment was done by calculating the R1 (I D /I G ) parameter, which is a relative integral intensity ratio and provides information about the proportion between the defected and crystalline structure within the tested sample. The higher the R1 ratio is, the lower is the level of crystallinity of the tested sample [15,20,[23][24][25]. Basing on the R1 ratio, no significant differences in the structure of the CNTs were observed and the CNTs in the layer were found to have similar level of crystallinity to the starting material.…”

Section: Raman Microspectroscopymentioning

confidence: 97%

Fabrication of multi-walled carbon nanotube layers with selected properties via electrophoretic deposition: physicochemical and biological characterization

et al. 2016

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The aim of the study was to fabricate and extensively characterize a layer of carbon nanotubes deposited on the surface of titanium, in order to prove that, by selecting proper type of carbon nanotubes and altering different parameters of the electrophoretic deposition process, we are able to obtain products having a different influence on cells-either favouring or inhibiting their survival. In the study, a novel mixture of solvents was used to suspend as-received tubes and then applied in the electrophoretic deposition. High charging capability and high yield of the obtained deposits are promising results when considering up-scaling the process. The surface of the obtained multi-walled carbon nanotubes-coated titanium samples was characterized using SEM, AFM, XPS and Raman microspectroscopy. The carbon nanotube layer showed nanorough topography and was formed of randomly and loosely distributed tubes, and XPS study revealed that there was a significant amount of C-O bonds. These properties were found to be favourable to osteoblast survival, spreading and growth.

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“…42,44,45 Raman spectroscopy, in combination with microscopy, can prove particularly useful for characterization of nanomaterials that have heterogeneous surfaces. [46][47][48][49][50] WITec, a German company, has recently launched the first commercially available SEM-Raman instrument. 15 The general assumption with conventional Raman spectroscopy is that first-order scattering occurs at the "Brillouin zone", where the wave vector is zero.…”

mentioning

confidence: 99%

“…It is a technique that is particularly relevant for toxicity studies because it does not require the use of fluorescent labels or staining procedures. [47][48][49][50] Fluorescent labels can alter the surface chemistry of the DDS, and such alterations can mask signs of toxicity exclusively due to the nanomaterial or potentially create toxicity that might not otherwise exist. Confocal-Raman is an instrument from which a substantial amount of information on the surface chemistry of the nanomaterial can be obtained.…”

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confidence: 99%

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Closing the gap: accelerating the translational process in nanomedicine by proposing standardized characterization techniques

Khorasani¹,

Weaver²,

Salvador-Morales³

2014

IJN

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On the cusp of widespread permeation of nanomedicine, academia, industry, and government have invested substantial financial resources in developing new ways to better treat diseases. Materials have unique physical and chemical properties at the nanoscale compared with their bulk or small-molecule analogs. These unique properties have been greatly advantageous in providing innovative solutions for medical treatments at the bench level. However, nanomedicine research has not yet fully permeated the clinical setting because of several limitations. Among these limitations are the lack of universal standards for characterizing nanomaterials and the limited knowledge that we possess regarding the interactions between nanomaterials and biological entities such as proteins. In this review, we report on recent developments in the characterization of nanomaterials as well as the newest information about the interactions between nanomaterials and proteins in the human body. We propose a standard set of techniques for universal characterization of nanomaterials. We also address relevant regulatory issues involved in the translational process for the development of drug molecules and drug delivery systems. Adherence and refinement of a universal standard in nanomaterial characterization as well as the acquisition of a deeper understanding of nanomaterials and proteins will likely accelerate the use of nanomedicine in common practice to a great extent.

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Temperature effects on the nitric acid oxidation of industrial grade multiwalled carbon nanotubes

Cited by 40 publications

References 49 publications

Mechanisms of Colloidal Stabilization of Oxidized Nanocarbons in the Presence of Polymers: Obtaining Highly Stable Colloids in Physiological Media

Mechanisms of Colloidal Stabilization of Oxidized Nanocarbons in the Presence of Polymers: Obtaining Highly Stable Colloids in Physiological Media

Fabrication of multi-walled carbon nanotube layers with selected properties via electrophoretic deposition: physicochemical and biological characterization

Closing the gap: accelerating the translational process in nanomedicine by proposing standardized characterization techniques

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