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Functionalized single-walled carbon nanotubes containing traces of iron as new negative MRI contrast agents for in vivo imaging

Unité de Pharmacologie Chimique et Génétique et d'Imagerie, Chimie ParisTech, Université Paris Descartes, Faculté des Sciences Pharmaceutiques et Biologiques, CNRS UMR 8151, Inserm U1022, Paris, F-75270 cedex, France.
Contrast Media & Molecular Imaging (Impact Factor: 3.33). 03/2012; 7(2):153-9. DOI: 10.1002/cmmi.474
Source: PubMed

ABSTRACT Single-walled carbon nanotubes (SWCNTs) containing traces of iron oxide were functionalized by noncovalent lipid-PEG or covalent carboxylic acid function to supply new efficient MRI contrast agents for in vitro and in vivo applications. Longitudinal (r(1)) and transversal (r(2)) water proton relaxivities were measured at 300 MHz, showing a stronger T(2) feature as an MRI contrast agent (r(2)/r(1)  = 190 for CO(2) H functionalisation). The r(2) relaxivity was demonstrated to be correlated to the presence of iron oxide in the SWNT-carboxylic function COOH, in comparison to iron-free ones. Biodistribution studies on mice after a systemic injection showed a negative MRI contrast in liver, suggesting the presence of the nanotubes in this organ until 48 h after i.v. injection. The presence of carbon nanotubes in liver was confirmed after ex vivo carbon extraction. Finally, cytotoxicity studies showed no apparent effect owing to the presence of the carbon nanotubes. The functionalized carbon nanotubes were well tolerated by the animals at the dose of 10 µg g(-1) body weight.

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    • "Nevertheless, applying CNTs to several fields of medicine requires detailed studies on their physical properties [6] [7] and an assessment of their toxicity level. A number of studies report the potential use of Single Walled Carbon Nanotubes (SWCNTs) and Multi Walled Carbon Nanotubes (MWCNTs) as both T 1 -based and T 2 -based MRI CAs [8] [9] [10] [11]. Unfortunately, due to the non-standardized synthesis protocols , scientific reports from different sources cannot be collated. "
    Carbon 07/2015; 94. DOI:10.1016/j.carbon.2015.07.091 · 6.16 Impact Factor
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    • "The contrast was attributed to the presence of iron impurities [21] and the magnetic resonance contrast observed was directly related to their iron content [22]. A range of methods have been used to modify CNTs potentially containing residual iron for MRI application, such as oxidation [23], non-covalent lipid-PEG modification [24], and ionic surfactants modification [25]. Therefore, the combination of polymer coated CNTs (as carriers) and attached metal ions (as contrast components) is expected to be highly suitable for use as MRI contrast agents with improved efficiency, dispersibility, and biocompatibility. "
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