Practical dissolution dynamic nuclear polarization

2021

Magn. Reson.

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Abstract. Dissolution dynamic nuclear polarization is used to prepare nuclear spin polarizations approaching unity. At present, 1H polarization quantification in the solid state remains fastidious due to the requirement of measuring thermal equilibrium signals. Line shape polarimetry of solid-state nuclear magnetic resonance spectra is used to determine several useful properties regarding the spin system under investigation. In the case of highly polarized nuclear spins, such as those prepared under the conditions of dissolution dynamic nuclear polarization experiments, the absolute polarization of a particular isotopic species within the sample may be directly inferred from the characteristics of the corresponding resonance line shape. In situations where direct measurements of polarization are complicated by deleterious phenomena, indirect estimates of polarization using coupled heteronuclear spins prove informative. We present a simple analysis of the 13C spectral line shape of [2-13C]sodium acetate based on the normalized deviation of the centre of gravity of the 13C peaks, which can be used to indirectly evaluate the proton polarization of the methyl group moiety and very likely the entire sample in the case of rapid and homogeneous 1H–1H spin diffusion. For the case of positive microwave irradiation, 1H polarization was found to increase with an increasing normalized centre of gravity deviation. These results suggest that, as a dopant, [2-13C]sodium acetate could be used to indirectly gauge 1H polarizations in standard sample formulations, which is potentially advantageous for (i) samples polarized in commercial dissolution dynamic nuclear polarization devices that lack 1H radiofrequency hardware, (ii) measurements that are deleteriously influenced by radiation damping or complicated by the presence of large background signals and (iii) situations where the acquisition of a thermal equilibrium spectrum is not feasible.

“…4. More details regarding how to acquire such build-up curves are given in the following reference (Elliott et al, 2021b…”

Section: C Nmr Peak Normalized Centre Of Gravity Deviation Vs 1 H Polarizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Solid-state 1H spin polarimetry by 13CH3 nuclear magnetic resonance

Elliott

2021

Magn. Reson.

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“…The low amplitude of NMR and MRI signals can be boosted by up to four orders of magnitude by implementing a variety of hyperpolarization techniques. 1,2 One such method, dissolution-dynamic nuclear polarization ( d DNP), 1–4 has been employed to strongly polarize nuclear spins in a range of molecules relevant to tumour characterization, ligand-protein binding detection and MRI. 5–9…”

Section: Introductionmentioning

confidence: 99%

“…In d DNP experiments, the spin system of interest is mixed with a suitable paramagnetic radical species in a solvent formulation which forms a glass when frozen at liquid helium temperature. 2 The DNP sample is irradiated with slightly non-resonant (with respect to the centre of the electron spin transition) microwaves inside a magnetic field, which act to transfer the high thermal equilibrium polarization of the electron spins to the nuclear spins of interest. 10 For nuclear spins with low gyromagnetic ratios, this process is achieved either directly or indirectly; in the latter case by employing nuclear polarization transfer techniques such as cross-polarization (CP) 11–15 and its variants.…”

Section: Introductionmentioning

confidence: 99%

Frozen water NMR lineshape analysis enables absolute polarization quantification

Koptyug

Phys. Chem. Chem. Phys.

Elliott

2022

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“…The electron polarization is transferred to the nuclear spins via microwave irradiation after which the frozen sample is dissolved using a hot solvent and transferred to an NMR spectrometer or MRI scanner for use of the hyperpolarized solution in the liquid state. This technique has the advantage of broad applicability, with polarization levels of tens of percent regularly achieved [22]. A first demonstration of d DNP coupled with ZULF-NMR detection was recently presented [23], where [1-13 C]pyruvic acid was hyperpolarized and detected with a portable zero-field spectrometer.…”

Section: Introductionmentioning

confidence: 99%

Zero- to Ultralow-Field Nuclear Magnetic Resonance Enhanced with Dissolution Dynamic Nuclear Polarization

Picazo‐Frutos

Blanchard

et al. 2022

Preprint

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Zero- to ultralow-field nuclear magnetic resonance is a modality of magnetic resonance experiment which does not require strong superconducting magnets. Contrary to conventional high-field nuclear magnetic resonance, it has the advantage of allowing high resolution detection of nuclear magnetism through metal as well as within heterogeneous media. To achieve high sensitivity, it is common to couple zero-field nuclear magnetic resonance with hyperpolarization techniques. To date, the most common technique is parahydrogen-induced polarization, which is only compatible with a small number of compounds. In this article, we establish dissolution dynamic nuclear polarization as a versatile method to enhance signals in zero-field nuclear magnetic resonance experiments on virtually all small molecules with > 1 s relaxation times. We show as first examples J-spectra of hyperpolarized [13C]sodium formate, [1-13C]glycine and [2-13C]sodium acetate. We find signal enhancements of up to 11000 compared with thermal prepolarization in a 2 T permanent magnet. To increase the signal in future experiments, we investigate the relaxation effects of the TEMPOL radicals used for the hyperpolarization process at zero- and ultralow-field.