Protonation tuned dipolar order mediated 1H→13C cross-polarization for dissolution-dynamic nuclear polarization experiments

Dissolution-dynamic nuclear polarization can be boosted by employing multiplecontact cross-polarization techniques to transfer polarization from 1H to 13C spins. The method is efficient and significantly reduces polarization build-up times, however, it involves high-power radiofrequency pulses in a superfluid helium environment which limit its implementation and applicability and prevent a significant scaling-up of the sample size. We propose to overcome this limitation by a stepwise transfer of polarization using a lowenergy and low-peak power radiofrequency pulse sequence where the 1H®13C polarization transfer is mediated by a dipolar spin order reservoir. An experimental demonstration is presented for [1-13C]sodium acetate. A solid-state 13C polarization of ~43.5% was achieved using this method with a build-up time constant of ~5.1 minutes, leading to a ~28.5% 13C polarization in the liquidstate after sample dissolution. The low-power multiple-step polarization transfer efficiency with respect to the most advanced and highest-power multiple-contact cross-polarization approach was found to be ~0.69.

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Boosting Dissolution-Dynamic Nuclear Polarization by Multiple-Step Dipolar Order Mediated 1H->13C Cross-Polarization

10.26434/chemrxiv.14377046.v1 ◽

2021 ◽

Author(s):

Stuart J. Elliott ◽

Olivier Cala ◽

Quentin Chappuis ◽

Samuel Cousin ◽

Morgan Ceillier ◽

...

Keyword(s):

Dynamic Nuclear Polarization ◽

Nuclear Polarization ◽

Pulse Sequence ◽

Polarization Transfer ◽

Cross Polarization ◽

Spin Order ◽

Sample Dissolution ◽

Dipolar Order ◽

Multiple Step ◽

Dissolution Dynamic Nuclear Polarization

Dissolution-dynamic nuclear polarization can be boosted by employing multiplecontact cross-polarization techniques to transfer polarization from 1H to 13C spins. The method is efficient and significantly reduces polarization build-up times, however, it involves high-power radiofrequency pulses in a superfluid helium environment which limit its implementation and applicability and prevent a significant scaling-up of the sample size. We propose to overcome this limitation by a stepwise transfer of polarization using a lowenergy and low-peak power radiofrequency pulse sequence where the 1H®13C polarization transfer is mediated by a dipolar spin order reservoir. An experimental demonstration is presented for [1-13C]sodium acetate. A solid-state 13C polarization of ~43.5% was achieved using this method with a build-up time constant of ~5.1 minutes, leading to a ~28.5% 13C polarization in the liquidstate after sample dissolution. The low-power multiple-step polarization transfer efficiency with respect to the most advanced and highest-power multiple-contact cross-polarization approach was found to be ~0.69.

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Dipolar order mediated 1H → 13C cross-polarization for dissolution-dynamic nuclear polarization

Magnetic Resonance ◽

10.5194/mr-1-89-2020 ◽

2020 ◽

Vol 1 (1) ◽

pp. 89-96

Author(s):

Stuart J. Elliott ◽

Samuel F. Cousin ◽

Quentin Chappuis ◽

Olivier Cala ◽

Morgan Ceillier ◽

...

Keyword(s):

Small Molecules ◽

Dynamic Nuclear Polarization ◽

Nuclear Polarization ◽

Polarization Transfer ◽

Cross Polarization ◽

Resonance Imaging ◽

Dipolar Order ◽

Imaging And Spectroscopy ◽

Single Polarization ◽

Dissolution Dynamic Nuclear Polarization

Abstract. Magnetic resonance imaging and spectroscopy often suffer from a low intrinsic sensitivity, which can in some cases be circumvented by the use of hyperpolarization techniques. Dissolution-dynamic nuclear polarization offers a way of hyperpolarizing 13C spins in small molecules, enhancing their sensitivity by up to 4 orders of magnitude. This is usually performed by direct 13C polarization, which is straightforward but often takes more than an hour. Alternatively, indirect 1H polarization followed by 1H→13C polarization transfer can be implemented, which is more efficient and faster but is technically very challenging and hardly implemented in practice. Here we propose to remove the main roadblocks of the 1H→13C polarization transfer process by using alternative schemes with the following: (i) less rf (radiofrequency) power; (ii) less overall rf energy; (iii) simple rf-pulse shapes; and (iv) no synchronized 1H and 13C rf irradiation. An experimental demonstration of such a simple 1H→13C polarization transfer technique is presented for the case of [1-13C]sodium acetate, and is compared with the most sophisticated cross-polarization schemes. A polarization transfer efficiency of ∼0.43 with respect to cross-polarization was realized, which resulted in a 13C polarization of ∼8.7 % after ∼10 min of microwave irradiation and a single polarization transfer step.

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Review of Elliott, et al Dipolar Order Mediated 1H-13C Cross-Polarization for Dissolution- Dynamic Nuclear Polarization

10.5194/mr-2020-4-rc2 ◽

2020 ◽

Author(s):

Anonymous

Keyword(s):

Dynamic Nuclear Polarization ◽

Nuclear Polarization ◽

Cross Polarization ◽

Dipolar Order ◽

Dissolution Dynamic Nuclear Polarization

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Dipolar Order Mediated 1H→13C Cross-Polarization for Dissolution-Dynamic Nuclear Polarization

10.5194/mr-2020-4 ◽

2020 ◽

Author(s):

Stuart J. Elliott ◽

Samuel F. Cousin ◽

Quentin Chappuis ◽

Olivier Cala ◽

Morgan Ceillier ◽

...

Keyword(s):

Small Molecules ◽

Dynamic Nuclear Polarization ◽

Nuclear Polarization ◽

Polarization Transfer ◽

Cross Polarization ◽

Rf Power ◽

Dipolar Order ◽

Imaging And Spectroscopy ◽

Single Polarization ◽

Dissolution Dynamic Nuclear Polarization

Abstract. Magnetic resonance imaging and spectroscopy often suffer from a low intrinsic sensitivity, which can in some cases be circumvented by the use of hyperpolarization techniques. Dissolution-dynamic nuclear polarization offers a way of hyperpolarizing 13C spins in small molecules, enhancing their sensitivity by up to four orders of magnitude. This is usually performed by direct 13C polarization, which is straightforward but often takes more than an hour. Alternatively, indirect 1H polarization followed by 1H→13C polarization transfer can be implemented, which is more efficient and faster but is technically very challenging and hardly implemented in practice. Here we propose to remove the main roadblocks of the 1H→13C polarization transfer process by using alternative schemes with: (i) less rf-power; (ii) less overall rf-energy; (iii) simple rf-pulse shapes; and (iv) no synchronized 1H and 13C rf-irradiation. An experimental demonstration of such a simple 1H→13C polarization transfer technique is presented for the case of [1-13C]sodium acetate, and is compared with the most sophisticated cross-polarization schemes. A polarization transfer efficiency of ~ 0.43 with respect to cross-polarization was realized, which resulted in a 13C polarization of ~ 8.7 % after ~ 10 minutes of microwave irradiation and a single polarization transfer step.

Download Full-text