Mechanisms of Gadographene-Mediated Proton Spin Relaxation

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

来源：Journal of Physical Chemistry C, 2013, 117(31): 16263-16273.

DOI：10.1021/jp406909b

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 break-through 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 (r(1)) and transverse (r(2)) 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 (T-M), molecular tumbling rate (T-R,), and local motion (T-fast) 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.

• 出版日期2013-8-8
• 单位西北大学