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Applications and Method Developments of Nuclear Magnetic Resonance (NMR) Spectroscopy and Hyperpolarized Magnetic Resonance Techniques

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A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Applied Chemistry".

Deadline for manuscript submissions: 30 April 2025 | Viewed by 16331

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Special Issue Editors

Dr. Nicholas Whiting

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Guest Editor

Department of Physics & Astronomy and Department of Molecular & Cellular Biosciences, Rowan University, Glassboro, NJ 08028, USA
Interests: hyperpolarized magnetic resonance; silicon nanoparticles; parahydrogen; dynamic nuclear polarization, nanoparticle hyperthermia

Dr. Youngbok Lee

E-Mail Website
Guest Editor

Department of Applied Chemistry, Hanyang University, Ansan 15588, Republic of Korea
Interests: hyperpolarization; dynamic nuclear polarization; MR spectroscopy and imaging; hyperpolarized magnetic resonance imaging application

Special Issue Information

Dear Colleagues,

Nuclear magnetic resonance (NMR) spectroscopy is unmatched in terms of the ability to non-destructively interrogate molecular structures and dynamics at high levels of specificity and resolution. Unfortunately, NMR is also limited by its inherently low sensitivity that hampers the study of samples with low analyte concentrations at fast time scales. The enhancements in sensitivity, which are gained through improvements in NMR methodology, as well as hyperpolarization techniques, bolster the expanse of studies that are achievable using NMR spectroscopy and MR imaging. For example, advances in hyperpolarization methods steadily improve both the magnitude of signal enhancement as well as its applicability to a diversity of chemical samples and biological systems. Colleagues are invited to contribute original research papers or reviews to this Special Issue of Molecules, which will report on recent advances in NMR methodology as well as hyperpolarization techniques, and elucidate the means with which these gains are leveraged for improved NMR applications.

Dr. Nicholas Whiting
Dr. Youngbok Lee
Guest Editors

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Keywords

hyperpolarized magnetic resonance
parahydrogen
dynamic nuclear polarization
optical pumping
contrast agents
low field

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Published Papers (7 papers)

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Research

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18 pages, 9732 KiB

Open AccessArticle

Hyperpolarized ¹³C NMR Reveals Pathway Regulation in Lactococcus lactis and Metabolic Similarities and Differences Across the Tree of Life

by Sebastian Meier, Alexandra L. N. Zahid, Lucas Rebien Jørgensen, Ke-Chuan Wang, Peter Ruhdal Jensen and Pernille Rose Jensen

Molecules 2024, 29(17), 4133; https://doi.org/10.3390/molecules29174133 - 30 Aug 2024

Cited by 1 | Viewed by 1082

Abstract

The control of metabolic networks is incompletely understood, even for glycolysis in highly studied model organisms. Direct real-time observations of metabolic pathways can be achieved in cellular systems with ¹³C NMR using dissolution Dynamic Nuclear Polarization (dDNP NMR). The method relies on a short-lived boost of NMR sensitivity using a redistribution of nuclear spin states to increase the alignment of the magnetic moments by more than four orders of magnitude. This temporary boost in sensitivity allows detection of metabolism with sub-second time resolution. Here, we hypothesized that dDNP NMR would be able to investigate molecular phenotypes that are not easily accessible with more conventional methods. The use of dDNP NMR allows real-time insight into carbohydrate metabolism in a Gram-positive bacterium (Lactoccocus lactis), and comparison to other bacterial, yeast and mammalian cells shows differences in the kinetic barriers of glycolysis across the kingdoms of life. Nevertheless, the accumulation of non-toxic precursors for biomass at kinetic barriers is found to be shared across the kingdoms of life. We further find that the visualization of glycolysis using dDNP NMR reveals kinetic characteristics in transgenic strains that are not evident when monitoring the overall glycolytic rate only. Finally, dDNP NMR reveals that resting Lactococcus lactis cells use the influx of carbohydrate substrate to produce acetoin rather than lactate during the start of glycolysis. This metabolic regime can be emulated using suitably designed substrate mixtures to enhance the formation of the C4 product acetoin more than 400-fold. Overall, we find that dDNP NMR provides analytical capabilities that may help to clarify the intertwined mechanistic determinants of metabolism and the optimal usage of biotechnologically important bacteria. Full article

(This article belongs to the Special Issue Applications and Method Developments of Nuclear Magnetic Resonance (NMR) Spectroscopy and Hyperpolarized Magnetic Resonance Techniques)

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13 pages, 2989 KiB

Open AccessArticle

Reconversion of Parahydrogen Gas in Surfactant-Coated Glass NMR Tubes

by Robert V. Chimenti, James Daley, James Sack, Jennifer Necsutu and Nicholas Whiting

Molecules 2023, 28(5), 2329; https://doi.org/10.3390/molecules28052329 - 2 Mar 2023

Cited by 1 | Viewed by 2404

Abstract

The application of parahydrogen gas to enhance the magnetic resonance signals of a diversity of chemical species has increased substantially in the last decade. Parahydrogen is prepared by lowering the temperature of hydrogen gas in the presence of a catalyst; this enriches the para spin isomer beyond its normal abundance of 25% at thermal equilibrium. Indeed, parahydrogen fractions that approach unity can be attained at sufficiently low temperatures. Once enriched, the gas will revert to its normal isomeric ratio over the course of hours or days, depending on the surface chemistry of the storage container. Although parahydrogen enjoys long lifetimes when stored in aluminum cylinders, the reconversion rate is significantly faster in glass containers due to the prevalence of paramagnetic impurities that are present within the glass. This accelerated reconversion is especially relevant for nuclear magnetic resonance (NMR) applications due to the use of glass sample tubes. The work presented here investigates how the parahydrogen reconversion rate is affected by surfactant coatings on the inside surface of valved borosilicate glass NMR sample tubes. Raman spectroscopy was used to monitor changes to the ratio of the (J: 0 → 2) vs. (J: 1 → 3) transitions that are indicative of the para and ortho spin isomers, respectively. Nine different silane and siloxane-based surfactants of varying size and branching structures were examined, and most increased the parahydrogen reconversion time by 1.5×–2× compared with equivalent sample tubes that were not treated with surfactant. This includes expanding the pH₂ reconversion time from 280 min in a control sample to 625 min when the same tube is coated with (3-Glycidoxypropyl)trimethoxysilane. Full article

(This article belongs to the Special Issue Applications and Method Developments of Nuclear Magnetic Resonance (NMR) Spectroscopy and Hyperpolarized Magnetic Resonance Techniques)

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16 pages, 3363 KiB

Open AccessArticle

Hyperpolarizing DNA Nucleobases via NMR Signal Amplification by Reversible Exchange

by Bryce E. Kidd, Max E. Gemeinhardt, Jamil A. Mashni, Jonathan L. Gesiorski, Liana B. Bales, Miranda N. Limbach, Roman V. Shchepin, Kirill V. Kovtunov, Igor V. Koptyug, Eduard Y. Chekmenev and Boyd M. Goodson

Molecules 2023, 28(3), 1198; https://doi.org/10.3390/molecules28031198 - 25 Jan 2023

Cited by 5 | Viewed by 2231

Abstract

The present work investigates the potential for enhancing the NMR signals of DNA nucleobases by parahydrogen-based hyperpolarization. Signal amplification by reversible exchange (SABRE) and SABRE in Shield Enables Alignment Transfer to Heteronuclei (SABRE-SHEATH) of selected DNA nucleobases is demonstrated with the enhancement (ε) of ¹H, ¹⁵N, and/or ¹³C spins in 3-methyladenine, cytosine, and 6-O-guanine. Solutions of the standard SABRE homogenous catalyst Ir(1,5-cyclooctadeine)(1,3-bis(2,4,6-trimethylphenyl)imidazolium)Cl (“IrIMes”) and a given nucleobase in deuterated ethanol/water solutions yielded low ¹H ε values (≤10), likely reflecting weak catalyst binding. However, we achieved natural-abundance enhancement of ¹⁵N signals for 3-methyladenine of ~3300 and ~1900 for the imidazole ring nitrogen atoms. ¹H and ¹⁵N 3-methyladenine studies revealed that methylation of adenine affords preferential binding of the imidazole ring over the pyrimidine ring. Interestingly, signal enhancements (ε~240) of both ¹⁵N atoms for doubly labelled cytosine reveal the preferential binding of specific tautomer(s), thus giving insight into the matching of polarization-transfer and tautomerization time scales. ¹³C enhancements of up to nearly 50-fold were also obtained for this cytosine isotopomer. These efforts may enable the future investigation of processes underlying cellular function and/or dysfunction, including how DNA nucleobase tautomerization influences mismatching in base-pairing. Full article

(This article belongs to the Special Issue Applications and Method Developments of Nuclear Magnetic Resonance (NMR) Spectroscopy and Hyperpolarized Magnetic Resonance Techniques)

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25 pages, 21000 KiB

Open AccessArticle

Investigating Rubidium Density and Temperature Distributions in a High-Throughput ¹²⁹Xe-Rb Spin-Exchange Optical Pumping Polarizer

by James E. Ball, Jim M. Wild and Graham Norquay

Molecules 2023, 28(1), 11; https://doi.org/10.3390/molecules28010011 - 20 Dec 2022

Cited by 3 | Viewed by 2596

Abstract

Accurate knowledge of the rubidium (Rb) vapor density,

[Rb]

, is necessary to correctly model the spin dynamics of

^{129}

Xe-Rb spin-exchange optical pumping (SEOP). Here we present a systematic evaluation of

[Rb]

within a high-throughput

^{129}

Xe-Rb hyperpolarizer [...] Read more.

Accurate knowledge of the rubidium (Rb) vapor density,

[Rb]

, is necessary to correctly model the spin dynamics of

^{129}

Xe-Rb spin-exchange optical pumping (SEOP). Here we present a systematic evaluation of

[Rb]

within a high-throughput

^{129}

Xe-Rb hyperpolarizer during continuous-flow SEOP. Near-infrared (

5^{2} S_{1 / 2} \to 5^{2} P_{1 / 2}

_{1}

)/5

^{2} P_{3 / 2}

_{2}

)) and violet (

5^{2} S_{1 / 2} \to 6^{2} P_{1 / 2}

^{2} P_{3 / 2}

) atomic absorption spectroscopy was used to measure

[Rb]

within 3.5 L cylindrical SEOP cells containing different spatial distributions and amounts of Rb metal. We were able to quantify deviation from the Beer-Lambert law at high optical depth for D

_{2}

and 6

^{2} P_{3 / 2}

absorption by comparison with measurements of the D

_{1}

and 6

^{2} P_{1 / 2}

absorption lines, respectively. D

_{2}

absorption deviates from the Beer-Lambert law at

{[Rb]}_{D_{2}} > 4 \times 10^{17}

^{- 3}

whilst 5

^{2}

_{1 / 2} \to 6^{2} P_{3 / 2}

absorption deviates from the Beer-Lambert law at

{[Rb]}_{6 P_{3 / 2}} > (4.16 \pm 0.01) \times 10^{19}

^{- 3}

. The measured

[Rb]

was used to estimate a

^{129}

Xe-Rb spin exchange cross section of

γ^{'} = (1.2 \pm 0.1) \times 10^{- 21}

^{3}

^{- 1}

, consistent with spin-exchange cross sections from the literature. Significant

[Rb]

heterogeneity was observed in a SEOP cell containing 1 g of Rb localized at the back of the cell. While

[Rb]

homogeneity was improved for a greater surface area of the Rb source distribution in the cell, or by using a Rb presaturator, the measured

[Rb]

was consistently lower than that predicted by saturation Rb vapor density curves. Efforts to optimize

[Rb]

and thermal management within spin polarizer systems are necessary to maximize potential future enhancements of this technology. Full article

(This article belongs to the Special Issue Applications and Method Developments of Nuclear Magnetic Resonance (NMR) Spectroscopy and Hyperpolarized Magnetic Resonance Techniques)

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11 pages, 1584 KiB

Open AccessArticle

Optical Dynamic Nuclear Polarization of ¹³C Spins in Diamond at a Low Field with Multi-Tone Microwave Irradiation

by Vladimir V. Kavtanyuk, Hyun Joon Lee, Sangwon Oh, Keunhong Jeong and Jeong Hyun Shim

Molecules 2022, 27(5), 1700; https://doi.org/10.3390/molecules27051700 - 4 Mar 2022

Cited by 2 | Viewed by 2774

Abstract

Majority of dynamic nuclear polarization (DNP) experiments have been requiring helium cryogenics and strong magnetic fields for a high degree of nuclear polarization. In this work, we instead demonstrate an optical hyperpolarization of naturally abundant

^{13}

C nuclei in a diamond crystal at [...] Read more.

^{13}

C nuclei in a diamond crystal at a low magnetic field and the room temperature. It exploits continuous laser irradiation for polarizing electronic spins of nitrogen vacancy centers and microwave irradiation for transferring the electronic polarization to

^{13}

C nuclear spins. We have studied the dependence of

^{13}

C polarization on laser and microwave powers. For the first time, a triplet structure corresponding to the

^{14}

N hyperfine splitting has been observed in the

^{13}

C polarization spectrum. By simultaneously exciting three microwave frequencies at the peaks of the triplet, we have achieved

^{13}

C bulk polarization of 0.113 %, leading to an enhancement of 90,000 over the thermal polarization at 17.6 mT. We believe that the multi-tone irradiation can be extended to further enhance the

^{13}

C polarization at a low magnetic field. Full article

(This article belongs to the Special Issue Applications and Method Developments of Nuclear Magnetic Resonance (NMR) Spectroscopy and Hyperpolarized Magnetic Resonance Techniques)

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Review

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19 pages, 2565 KiB

Open AccessReview

Measurements of Nuclear Magnetic Shielding in Molecules

by Karol Jackowski and Marcin Wilczek

Molecules 2024, 29(11), 2617; https://doi.org/10.3390/molecules29112617 - 2 Jun 2024

Cited by 1 | Viewed by 1524

Abstract

The origin of nuclear magnetic shielding in diamagnetic molecules is discussed, pointing out various contributions to the shielding from electrons and the effects of intra- and intermolecular interactions. In NMR practice, chemical shifts are determined first as the measure of shielding in observed samples. The descriptions of shielding and chemical shifts are not fully consistent. Gas phase studies permit the withdrawal of intermolecular contributions from shielding and obtaining the magnetic shielding data in isolated molecules. The shielding determination in molecules is possible using at least three methods delivering the reference shielding standards for selected nuclei. The known shielding of one magnetic nucleus can be transferred to other nuclei if the appropriate nuclear magnetic moments are available with satisfactory accuracy. It is possible to determine the nuclear magnetic dipole moments using the most advanced ab initio shielding calculations jointly with the NMR frequencies measurements for small-sized isolated molecules. Helium-3 gas is postulated as all the molecules’ primary and universal reference standard of shielding. It can be easily applied using common deuterium lock solvents as the secondary reference standards. The measurements of absolute shielding are available for everyone with the use of standard NMR spectrometers. Full article

(This article belongs to the Special Issue Applications and Method Developments of Nuclear Magnetic Resonance (NMR) Spectroscopy and Hyperpolarized Magnetic Resonance Techniques)

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49 pages, 17959 KiB

Open AccessReview

Preclinical MRI Using Hyperpolarized ¹²⁹Xe

by Stephen Kadlecek, Yonni Friedlander and Rohan S. Virgincar

Molecules 2022, 27(23), 8338; https://doi.org/10.3390/molecules27238338 - 29 Nov 2022

Cited by 3 | Viewed by 2437

Abstract

Although critical for development of novel therapies, understanding altered lung function in disease models is challenging because the transport and diffusion of gases over short distances, on which proper function relies, is not readily visualized. In this review we summarize progress introducing hyperpolarized ¹²⁹Xe imaging as a method to follow these processes in vivo. The work is organized in sections highlighting methods to observe the gas replacement effects of breathing (Gas Dynamics during the Breathing Cycle) and gas diffusion throughout the parenchymal airspaces (3). We then describe the spectral signatures indicative of gas dissolution and uptake (4), and how these features can be used to follow the gas as it enters the tissue and capillary bed, is taken up by hemoglobin in the red blood cells (5), re-enters the gas phase prior to exhalation (6), or is carried via the vasculature to other organs and body structures (7). We conclude with a discussion of practical imaging and spectroscopy techniques that deliver quantifiable metrics despite the small size, rapid motion and decay of signal and coherence characteristic of the magnetically inhomogeneous lung in preclinical models (8). Full article

(This article belongs to the Special Issue Applications and Method Developments of Nuclear Magnetic Resonance (NMR) Spectroscopy and Hyperpolarized Magnetic Resonance Techniques)

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