Generating highly polarized nuclear spins in solution using dynamic nuclear polarization

Wolber, Jan; Ellner, F; Fridlund, Björn; Gram, Andreas; Jóhannesson, Haukur; Hansson, Georg; Hansson, LH; Lerche, Mathilde Hauge; Månsson, Sven; Servin, Rolf; Thaning, Mikkel; Golman, Klaes; Ardenkjaer-Larsen, JH

doi:10.1016/j.nima.2004.03.171

Cited by 148 publications

(194 citation statements)

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“…In parallel, a monotonic decrease of the polarization time T pol from a maximum of 5000 s to a minimum of 475 s is observed. A similar trend was reported in [29] for a sample of [ 13 C]urea, actually one of the first endogenous molecules studied for biomedical applications, dissolved in glycerol to give a nearly saturated solution. On increasing the trityl concentration from 15 to 25 mM (FIG.…”

Section: Discussionsupporting

confidence: 81%

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Relevance of electron spin dissipative processes to dynamic nuclear polarization via thermal mixing

Serra

Filibian

Carretta

et al. 2014

Phys. Chem. Chem. Phys.

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The available theoretical approaches aiming at describing Dynamic Nuclear spin Polarization (DNP) in solutions containing molecules of biomedical interest and paramagnetic centers are not able to model the behaviour observed upon varying the concentration of trityl radicals or the polarization enhancement caused by moderate addition of gadolinium complexes. In this manuscript, we first show experimentally that the nuclear steady state polarization reached in solutions of pyruvic acid with 15 mM trityl radicals is substantially independent from the average internuclear distance. This evidences a leading role of electron (over nuclear) spin relaxation processes in determining the ultimate performances of DNP. Accordingly, we have devised a variant of the Thermal Mixing model for inhomogenously broadened electron resonance lines which includes a relaxation term describing the exchange of magnetic anisotropy energy of the electron spin system with the lattice. Thanks to this additional term, the dependence of the nuclear polarization on the electron concentration can be properly accounted for. Moreover, the model predicts a strong increase of the final polarization on shortening the electron spin-lattice relaxation time, providing a possible explanation for the effect of gadolinium doping.

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Section: Discussionsupporting

confidence: 81%

“…In that case (that will object of future studies) the electron-nucleus contact and the nuclear leakage are likely to be strong enough to be involved in the evolution of the electron profile. 25 mM (data from [29]). …”

Section: Discussionmentioning

confidence: 98%

Relevance of electron spin dissipative processes to dynamic nuclear polarization via thermal mixing

Serra

Filibian

Carretta

et al. 2014

Phys. Chem. Chem. Phys.

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“…17,18,20,21,31,34,49 Trityl OX063, the stable organic radical used in this work, has a very narrow EPR linewidth that makes it ideal for polarizing low-γ nuclei such as 13 C. When using this free radical to polarize low-γ nuclei such as 13 C spins, DNP data at 3.35 T and temperatures close to 1 K have shown indications of thermal mixing (TM) as the predominant DNP mechanism. 24,[50][51][52][53] Other DNP data at similar conditions suggested that the mechanism could be a combination of the solid effect (SE) and cross effect (CE). [54][55][56] Unlike the solid effect (SE) 57 and the cross effect (CE), 54,58 TM is a many-spin model for polarization that treats spin interactions as thermodynamic reservoirs.…”

Section: Resultsmentioning

confidence: 94%

Influence of Dy3+ and Tb3+ doping on 13C dynamic nuclear polarization

Niedbalski

Parish

Kiswandhi

et al. 2017

The Journal of Chemical Physics

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Dynamic nuclear polarization (DNP) is a technique that uses a microwave-driven transfer of high spin alignment from electrons to nuclear spins. This is most effective at low temperature and high magnetic field, and with the invention of the dissolution method, the amplified nuclear magnetic resonance (NMR) signals in the frozen state in DNP can be harnessed in the liquid-state at physiologically acceptable temperature for in vitro and in vivo metabolic studies. A current optimization practice in dissolution DNP is to dope the sample with trace amounts of lanthanides such as Gd 3+ or Ho 3+ , which further improves the polarization. While Gd 3+ and Ho 3+ have been optimized for use in dissolution DNP, other lanthanides have not been exhaustively studied for use in 13 C DNP applications. In this work, two additional lanthanides with relatively high magnetic moments, Dy 3+ and Tb 3+ , were extensively optimized and tested as doping additives for 13 C DNP at 3.35 T and 1.2 K. We have found that both of these lanthanides are also beneficial additives, to a varying degree, for 13 C DNP. The optimal concentrations of Dy 3+ (1.5 mM) and Tb 3+ (0.25 mM) for 13 C DNP were found to be less than that of Gd 3+ (2 mM). W-band electron paramagnetic resonance shows that these enhancements due to Dy 3+ and Tb 3+ doping are accompanied by shortening of electron T 1 of trityl OX063 free radical. Furthermore, when dissolution was employed, Tb 3+ -doped samples were found to have similar liquid-state 13 C NMR signal enhancements compared to samples doped with Gd 3+ , and both Tb 3+ and Dy 3+ had a negligible liquid-state nuclear T 1 shortening effect which contrasts with the significant reduction in T 1 when using Gd 3+ . Our results show that Dy 3+ doping and Tb 3+ doping have a beneficial impact on 13 C DNP both in the solid and liquid states, and that Tb 3+ in particular could be used as a potential alternative to Gd 3+ in 13 C dissolution DNP experiments. Published by AIP Publishing.

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“…13 C was chosen as a target nuclear spin because (1) carbon is present in almost all relevant molecules in biology, (2) isotope labeling is often affordable, (3) the thermal equilibrium background signal of 13 C in vivo is below detection limit and therefore not interfering, in contrast to 1 H, and (4) quaternary carbons have relatively long T 1 's in liquid state at room temperature after dissolution so that the hyperpolarization can survive on sufficiently long timescales to probe relevant bio-chemical processes. Trityl radicals, a class of radicals with narrow ESR lines, are especially suited for the direct polarization of 13 C [3,7,8]. The two key parameters that describe the DNP efficiency of a free radical are (1) the maximum polarization P ( 13 C) achievable and (2) the time constant s DNP ( 13 C) of the approach to the DNP equilibrium.…”

Section: Dnp Polarizermentioning

confidence: 99%

“…D-DNP has rapidly found a 'killer' application in in vivo MRI. The high signal-to-noise ratio provided by d-DNP for 13 C labeled molecules has enabled the observation of hyperpolarized [1][2][3][4][5][6][7][8][9][10][11][12][13] C pyruvate in humans shortly after infusion, and its enzymatic in-cello conversion into 1-…”

Section: Dissolution and Liquid State Mri And Nmr Applicationsmentioning

confidence: 99%