Mechanisms of gadographene-mediated proton spin relaxation

Andy H. Hung, Matthew C. Duch, Giacomo Parigi, Matthew W. Rotz, Lisa M. Manus, Daniel J. Mastarone, Kevin T. Dam, Colton C. Gits, Keith W. MacRenaris, Claudio Luchinat, Mark C. Hersam, Thomas J. Meade

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Abstract

Gd(III) associated with carbon nanomaterials relaxes water proton spins at an effectiveness that approaches or exceeds the theoretical limit for a single bound water molecule. These Gd(III)-labeled materials represent a potential breakthrough in sensitivity for Gd(III)-based contrast agents used for magnetic resonance imaging (MRI). However, their mechanism of action remains unclear. A gadographene library encompassing GdCl3, two different Gd(III) complexes, graphene oxide (GO), and graphene suspended by two different surfactants and subjected to varying degrees of sonication was prepared and characterized for their relaxometric properties. Gadographene was found to perform comparably to other Gd(III)-carbon nanomaterials; its longitudinal (r1) and transverse (r2) relaxivity are modulated between 12-85 mM-1 s-1 and 24-115 mM-1 s-1, respectively, depending on the Gd(III)-carbon backbone combination. The unusually large relaxivity and its variance can be understood under the modified Florence model incorporating the Lipari-Szabo approach. Changes in hydration number (q), water residence time (τM), molecular tumbling rate (τR), and local motion (τfast) sufficiently explain most of the measured relaxivities. Furthermore, results implicated the coupling between graphene and Gd(III) as a minor contributor to proton spin relaxation.

Original languageEnglish
Pages (from-to)16263-16273
Number of pages11
JournalJournal of Physical Chemistry C
Volume117
Issue number31
DOIs
Publication statusPublished - Aug 8 2013

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ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Electronic, Optical and Magnetic Materials
  • Surfaces, Coatings and Films
  • Energy(all)

Cite this

Hung, A. H., Duch, M. C., Parigi, G., Rotz, M. W., Manus, L. M., Mastarone, D. J., ... Meade, T. J. (2013). Mechanisms of gadographene-mediated proton spin relaxation. Journal of Physical Chemistry C, 117(31), 16263-16273. https://doi.org/10.1021/jp406909b