Dynamic nuclear polarization properties of nitroxyl radicals used in Overhauser-enhanced MRI for simultaneous molecular imaging

Benial, A. Milton Franklin; Ichikawa, Kazuhiro; Murugesan, Ramachandran; Yamada, Ken Ichi; Utsumi, Hideo

doi:10.1016/j.jmr.2006.06.025

Cited by 46 publications

(39 citation statements)

References 35 publications

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“…Despite the fact that our measured maximum enhancements of #50, #36 and #12 are slightly lower than those reported for similar systems and hardware setups [14,17], it is noteworthy that the ENDOR probehead employed in this study is used at EPR resonance conditions (8.41 GHz/0.30 T) for which this commercial probehead is not optimized. The microwave absorption characteristics are rather poor: it is highly overcoupled and microwave reflections already significantly diminish the performance.…”

Section: Discussioncontrasting

confidence: 72%

“…This is a result which can be expected for nitroxide-based radicals because of unresolved 1 H hyperfine splittings [14]. For TEMPOL, the 1 H DNP enhancement curve closely follows the EPR spectrum with the exception of the left flanks of the individual EPR lines.…”

Section: Resultssupporting

confidence: 64%

“…This lower DNP enhancement can be due to the fact that the dipolar couplings between the unpaired electron spins and the proton nuclear spins of the water molecules are more efficient, as has also been reported previously for TAM and nitroxides [10,14,16].…”

Section: Discussionsupporting

confidence: 66%

“…The theoretically predicted maximum 1 H-DNP enhancement factor in systems containing 14 N-nitroxide radicals at room temperature is #110 [15]. This value is significantly greater than the ones that can be obtained in the mobile polarizer for our 14 N-nitroxide radicals dissolved in a 55:45 mixture of glycerol and water (#80 and #60 for poly(DADMAC) and TEMPOL, respectively).…”

Section: Discussionmentioning

confidence: 68%

“…The maximum DNP enhancement that can be achieved with our experimental conditions can be obtained by plotting the reciprocal Overhauser enhancement (1 # enhancement factor) #1 against the reciprocal EPR power level P #1 which should show a linear dependence [10,14,15]. The data points in Fig.…”

Section: Resultsmentioning

confidence: 99%

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A Mobile DNP Polarizer for Clinical Applications

et al. 2008

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Abstract. A mobile and low-cost apparatus for dynamic nuclear polarization (DNP) hyperpolarization based on a Halbach magnet is presented and its performance is demonstrated at room temperature and with three different radical species dissolved in a glycerol-water mixture. DNP enhancement factors for a triarylmethyl-based radical, TEMPOL and a polyelectrolyte spin-labeled with nitroxide radicals are measured as a function of the microwave power, and the extrapolated maximum enhancement factors are compared. The spin-labeled polyelectrolyte shows the best DNP efficiency and 1 H DNP enhancement factors up to #50 were observed and a maximum enhancement factor of #80 was projected. The results demonstrate that with the new mobile apparatus reliable DNP experiments can be performed with reasonably high 1 H-DNP enhancements.

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Section: Discussioncontrasting

confidence: 72%

Section: Resultssupporting

confidence: 64%

Section: Discussionsupporting

confidence: 66%

Section: Discussionmentioning

confidence: 68%

Section: Resultsmentioning

confidence: 99%

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A Mobile DNP Polarizer for Clinical Applications

et al. 2008

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Spin Labels and Spin Probes

Bardelang

Hardy

Ouari

et al. 2012

Encyclopedia of Radicals in Chemistry, Biology and Materials

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The electron paramagnetic resonance (EPR) parameters of a free radical depend strongly on its microenvironment and stable radicals can be used as reporter molecules for the EPR probing of various chemical and biological systems. Nowadays, nitroxides and trityl radicals are the most important spin labels or spin probes and their use in various applications, spin labeling, spin trapping, oximetry, pH measurement, evaluation of redox status, interactions in supramolecular systems, and so on, are examined.

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