1
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Scott FJ, Eddy S, Gullion T, Mentink-Vigier F. Sorbitol-Based Glass Matrices Enable Dynamic Nuclear Polarization beyond 200 K. J Phys Chem Lett 2024; 15:8743-8751. [PMID: 39162721 DOI: 10.1021/acs.jpclett.4c02054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/21/2024]
Abstract
In magic angle spinning dynamic nuclear polarization (MAS-DNP) experiments, paramagnetic species are often dispersed in rigid glass-forming matrices such as glycerol/water mixtures, but their modest glass-transition temperature (Tg) restricts the viable temperature range for MAS-DNP. To expand applications of DNP at higher temperatures, new matrices and physical insights are required. Here we demonstrate that sorbitol, Tg ≈ 267 K, advantageously replaces glycerol, Tg ≈ 190 K, to carry out DNP at higher temperature while maintaining an identical 13C NMR spectrum footprint and thus minimizing spectral overlap. DNP stops being effective in glycerol/water at ∼180 K, but sorbitol/DMSO gives a significant enhancement at 230 K with AsymPol-POK biradicals at 600 MHz/395 GHz. For the first time, a simple analytical model is proposed that provides physical insights and explains the effect of biradical concentration, the temperature dependence of the enhancement, the signal buildup times, and the enhanced signal-to-noise ratio. The model reveals that electron spin relaxation is the limiting factor for high-temperature DNP in the case of AsymPol-POK. We showcase the efficacy of this new DNP formulation on an intriguing chitin sample extracted from cicada exoskeleton which allowed for the recording of rapid heteronuclear correlation spectra at 100 and 225 K.
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Affiliation(s)
- Faith J Scott
- National High Magnetic Field Laboratory, Florida State University, 1800 E. Paul Dirac Drive, Tallahassee, Florida 32310, United States
| | - Samuel Eddy
- Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Terry Gullion
- Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Frédéric Mentink-Vigier
- National High Magnetic Field Laboratory, Florida State University, 1800 E. Paul Dirac Drive, Tallahassee, Florida 32310, United States
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2
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Scott FJ, Dubroca T, Schurko RW, Hill S, Long JR, Mentink-Vigier F. Characterization of dielectric properties and their impact on MAS-DNP NMR applications. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2024; 365:107742. [PMID: 39116460 DOI: 10.1016/j.jmr.2024.107742] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2024] [Revised: 06/17/2024] [Accepted: 07/13/2024] [Indexed: 08/10/2024]
Abstract
The dielectric properties of materials play a crucial role in the propagation and absorption of microwave beams employed in Magic Angle Spinning - Dynamic Nuclear Polarization (MAS-DNP) NMR experiments. Despite ongoing optimization efforts in sample preparation, routine MAS-DNP NMR applications often fall short of theoretical sensitivity limits. Offering a different perspective, we report the refractive indices and extinction coefficients of diverse materials used in MAS-DNP NMR experiments, spanning a frequency range from 70 to 960 GHz. Knowledge of their dielectric properties enables the accurate simulation of electron nutation frequencies, thereby guiding the design of more efficient hardware and sample preparation of biological or material samples. This is illustrated experimentally for four different rotor materials (sapphire, yttria-stabilized zirconia (YSZ), aluminum nitride (AlN), and SiAlON ceramics) used for DNP at 395 GHz/1H 600 MHz. Finally, electromagnetic simulations and state-of-the-art MAS-DNP numerical simulations provide a rational explanation for the observed magnetic field dependence of the enhancement when using nitroxide biradicals, offering insights that will improve MAS-DNP NMR at high magnetic fields.
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Affiliation(s)
- Faith J Scott
- National High Magnetic Field Laboratory, Florida State University, 1800 E. Paul Dirac Dr., Tallahassee, FL 32310, USA
| | - Thierry Dubroca
- National High Magnetic Field Laboratory, Florida State University, 1800 E. Paul Dirac Dr., Tallahassee, FL 32310, USA
| | - Robert W Schurko
- National High Magnetic Field Laboratory, Florida State University, 1800 E. Paul Dirac Dr., Tallahassee, FL 32310, USA; Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, USA
| | - Stephen Hill
- National High Magnetic Field Laboratory, Florida State University, 1800 E. Paul Dirac Dr., Tallahassee, FL 32310, USA; Department of Physics, Florida State University, Tallahassee, FL 32306, USA
| | - Joanna R Long
- National High Magnetic Field Laboratory, Florida State University, 1800 E. Paul Dirac Dr., Tallahassee, FL 32310, USA; Department of Biochemistry and Molecular Biology, University of Florida, PO Box 100245, Gainesville, FL 32610, USA.
| | - Frédéric Mentink-Vigier
- National High Magnetic Field Laboratory, Florida State University, 1800 E. Paul Dirac Dr., Tallahassee, FL 32310, USA.
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3
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Dickwella Widanage MC, Gautam I, Sarkar D, Mentink-Vigier F, Vermaas JV, Ding SY, Lipton AS, Fontaine T, Latgé JP, Wang P, Wang T. Adaptative survival of Aspergillus fumigatus to echinocandins arises from cell wall remodeling beyond β-1,3-glucan synthesis inhibition. Nat Commun 2024; 15:6382. [PMID: 39085213 PMCID: PMC11291495 DOI: 10.1038/s41467-024-50799-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2024] [Accepted: 07/17/2024] [Indexed: 08/02/2024] Open
Abstract
Antifungal echinocandins inhibit the biosynthesis of β-1,3-glucan, a major and essential polysaccharide component of the fungal cell wall. However, the efficacy of echinocandins against the pathogen Aspergillus fumigatus is limited. Here, we use solid-state nuclear magnetic resonance (ssNMR) and other techniques to show that echinocandins induce dynamic changes in the assembly of mobile and rigid polymers within the A. fumigatus cell wall. The reduction of β-1,3-glucan induced by echinocandins is accompanied by a concurrent increase in levels of chitin, chitosan, and highly polymorphic α-1,3-glucans, whose physical association with chitin maintains cell wall integrity and modulates water permeability. The rearrangement of the macromolecular network is dynamic and controls the permeability and circulation of the drug throughout the cell wall. Thus, our results indicate that echinocandin treatment triggers compensatory rearrangements in the cell wall that may help A. fumigatus to tolerate the drugs' antifungal effects.
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Affiliation(s)
- Malitha C Dickwella Widanage
- Department of Chemistry, Michigan State University, East Lansing, MI, USA
- National High Magnetic Field Laboratory, Tallahassee, FL, USA
| | - Isha Gautam
- Department of Chemistry, Michigan State University, East Lansing, MI, USA
| | | | | | - Josh V Vermaas
- MSU-DOE Plant Research Laboratory, East Lansing, MI, USA
- Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA
| | - Shi-You Ding
- Department of Plant Biology, Michigan State University, East Lansing, MI, USA
| | - Andrew S Lipton
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA, USA
| | - Thierry Fontaine
- Institut Pasteur, Université Paris Cité, INRAE, USC2019, Unité Biologie et Pathogénicité Fongiques, F-, 75015, Paris, France
| | - Jean-Paul Latgé
- Institute of Molecular Biology and Biotechnology, University of Crete, Heraklion, Greece
| | - Ping Wang
- Departments of Microbiology, Immunology and Parasitology, Louisiana State University Health Sciences Center, New Orleans, LA, USA
| | - Tuo Wang
- Department of Chemistry, Michigan State University, East Lansing, MI, USA.
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4
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Badoni S, Berruyer P, Emsley L. Optimal sensitivity for 1H detected relayed DNP of organic solids at fast MAS. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2024; 360:107645. [PMID: 38401477 DOI: 10.1016/j.jmr.2024.107645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Revised: 01/30/2024] [Accepted: 02/09/2024] [Indexed: 02/26/2024]
Abstract
Dynamic nuclear polarization (DNP) combined with high magnetic fields and fast magic angle spinning (MAS) has opened up a new avenue for the application of exceptionally sensitive 1H NMR detection schemes to study protonated solids. Recently, it has been shown that DNP experiments at fast MAS rates lead to slower spin diffusion and hence reduced DNP enhancements for impregnated materials. However, DNP enhancements alone do not determine the overall sensitivity of a NMR experiment. Here we measure the overall sensitivity of one-dimensional 1H detected relayed DNP experiments as a function of the MAS rate in the 20-60 kHz regime using 0.7 mm diameter rotors at 21.2 T. Although faster MAS rates are detrimental for the DNP enhancement on the target material, due to slower spin diffusion, we find that with increasing spinning rates the gain in sensitivity due to 1H line-narrowing and the folding-in of sideband intensity compensates a large part of the loss of overall hyperpolarization. We find that sensitivity depends on the atomic site in the molecule, and is maximised at between 40 and 50 kHz MAS for the sample of L-histidine.HCl·H2O studied here. There is a 10-20 % difference in sensitivity between the optimum MAS rate and the fastest rate currently accessible (60 kHz).
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Affiliation(s)
- Saumya Badoni
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Pierrick Berruyer
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Lyndon Emsley
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
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5
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Chatterjee S, Venkatesh A, Sigurdsson ST, Mentink-Vigier F. Role of Protons in and around Strongly Coupled Nitroxide Biradicals for Cross-Effect Dynamic Nuclear Polarization. J Phys Chem Lett 2024; 15:2160-2168. [PMID: 38364262 DOI: 10.1021/acs.jpclett.3c03472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2024]
Abstract
In magic angle spinning dynamic nuclear polarization (DNP), biradicals such as bis-nitroxides are used to hyperpolarize protons under microwave irradiation through the cross-effect mechanism. This mechanism relies on electron-electron spin interactions (dipolar coupling and exchange interaction) and electron-nuclear spin interactions (hyperfine coupling) to hyperpolarize the protons surrounding the biradical. This hyperpolarization is then transferred to the bulk sample via nuclear spin diffusion. However, the involvement of the protons in the biradical in the cross-effect DNP process has been under debate. In this work, we address this question by exploring the hyperpolarization pathways in and around bis-nitroxides. We demonstrate that for biradicals with strong electron-electron interactions, as in the case of the AsymPols, the protons on the biradical may not be necessary to quickly generate hyperpolarization. Instead, such biradicals can efficiently, and directly, polarize the surrounding protons of the solvent. The findings should impact the design of the next generation of biradicals.
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Affiliation(s)
- Satyaki Chatterjee
- University of Iceland, Department of Chemistry, Science Institute, Dunhaga 3, 107 Reykjavik, Iceland
| | - Amrit Venkatesh
- National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, United States
| | - Snorri Th Sigurdsson
- University of Iceland, Department of Chemistry, Science Institute, Dunhaga 3, 107 Reykjavik, Iceland
| | - Frédéric Mentink-Vigier
- National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, United States
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6
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Venkatesh A, Casano G, Wei R, Rao Y, Lingua H, Karoui H, Yulikov M, Ouari O, Emsley L. Rational Design of Dinitroxide Polarizing Agents for Dynamic Nuclear Polarization to Enhance Overall NMR Sensitivity. Angew Chem Int Ed Engl 2024; 63:e202317337. [PMID: 38193258 DOI: 10.1002/anie.202317337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Revised: 01/03/2024] [Accepted: 01/08/2024] [Indexed: 01/10/2024]
Abstract
We evaluate the overall sensitivity gains provided by a series of eighteen nitroxide biradicals for dynamic nuclear polarization (DNP) solid-state NMR at 9.4 T and 100 K, including eight new biradicals. We find that in the best performing group the factors contributing to the overall sensitivity gains, namely the DNP enhancement, the build-up time, and the contribution factor, often compete with each other leading to very similar overall sensitivity across a range of biradicals. NaphPol and HydroPol are found to provide the best overall sensitivity factors, in organic and aqueous solvents respectively. One of the new biradicals, AMUPolCbm, provides high sensitivity for all three solvent formulations measured here, and can be considered to be a "universal" polarizing agent.
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Affiliation(s)
- Amrit Venkatesh
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015, Lausanne, Switzerland
- Current address: National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, USA
| | - Gilles Casano
- Aix Marseille Univ, CNRS, Institut de Chimie Radicalaire UMR 7273, 13013, Marseille, France
| | - Ran Wei
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015, Lausanne, Switzerland
| | - Yu Rao
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015, Lausanne, Switzerland
| | - Hugo Lingua
- Aix Marseille Univ, CNRS, Institut de Chimie Radicalaire UMR 7273, 13013, Marseille, France
| | - Hakim Karoui
- Aix Marseille Univ, CNRS, Institut de Chimie Radicalaire UMR 7273, 13013, Marseille, France
| | - Maxim Yulikov
- Laboratory of Physical Chemistry, Department of Chemistry, ETH Zürich, 8093, Zürich, Switzerland
| | - Olivier Ouari
- Aix Marseille Univ, CNRS, Institut de Chimie Radicalaire UMR 7273, 13013, Marseille, France
| | - Lyndon Emsley
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015, Lausanne, Switzerland
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7
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Harrabi R, Halbritter T, Alarab S, Chatterjee S, Wolska-Pietkiewicz M, Damodaran KK, van Tol J, Lee D, Paul S, Hediger S, Sigurdsson ST, Mentink-Vigier F, De Paëpe G. AsymPol-TEKs as efficient polarizing agents for MAS-DNP in glass matrices of non-aqueous solvents. Phys Chem Chem Phys 2024; 26:5669-5682. [PMID: 38288878 PMCID: PMC10849081 DOI: 10.1039/d3cp04271e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Accepted: 01/22/2024] [Indexed: 02/03/2024]
Abstract
Two polarizing agents from the AsymPol family, AsymPol-TEK and cAsymPol-TEK (methyl-free version) are introduced for MAS-DNP applications in non-aqueous solvents. The performance of these new biradicals is rationalized in detail using a combination of electron paramagnetic resonance spectroscopy, density functional theory, molecular dynamics and quantitative MAS-DNP spin dynamics simulations. By slightly modifying the experimental protocol to keep the sample temperature low at insertion, we are able to obtain reproducable DNP-NMR data with 1,1,2,2-tetrachloroethane (TCE) at 100 K, which facilitates optimization and comparison of different polarizing agents. At intermediate magnetic fields, AsymPol-TEK and cAsymPol-TEK provide 1.5 to 3-fold improvement in sensitivity compared to TEKPol, one of the most widely used polarizing agents for organic solvents, with significantly shorter DNP build-up times of ∼1 s and ∼2 s at 9.4 and 14.1 T respectively. In the course of the work, we also isolated and characterized two diastereoisomers that can form during the synthesis of AsymPol-TEK; their difference in performance is described and discussed. Finally, the advantages of the AsymPol-TEKs are demonstrated by recording 2D 13C-13C correlation experiments at natural 13C-abundance of proton-dense microcrystals and by polarizing the surface of ZnO nanocrystals (NCs) coated with diphenyl phosphate ligands. For those experiments, cAsymPol-TEK yielded a three-fold increase in sensitivity compared to TEKPol, corresponding to a nine-fold time saving.
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Affiliation(s)
- Rania Harrabi
- Univ. Grenoble Alpes, CEA, CNRS, IRIG, MEM, 38000 Grenoble, France.
| | - Thomas Halbritter
- University of Iceland, Department of Chemistry, Science Institute, Dunhaga 3, 107 Reykjavik, Iceland.
| | - Shadi Alarab
- Univ. Grenoble Alpes, CEA, CNRS, IRIG, MEM, 38000 Grenoble, France.
| | - Satyaki Chatterjee
- University of Iceland, Department of Chemistry, Science Institute, Dunhaga 3, 107 Reykjavik, Iceland.
| | | | - Krishna K Damodaran
- University of Iceland, Department of Chemistry, Science Institute, Dunhaga 3, 107 Reykjavik, Iceland.
| | - Johan van Tol
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32301, USA.
| | - Daniel Lee
- Univ. Grenoble Alpes, CEA, CNRS, IRIG, MEM, 38000 Grenoble, France.
| | - Subhradip Paul
- Univ. Grenoble Alpes, CEA, CNRS, IRIG, MEM, 38000 Grenoble, France.
| | - Sabine Hediger
- Univ. Grenoble Alpes, CEA, CNRS, IRIG, MEM, 38000 Grenoble, France.
| | - Snorri Th Sigurdsson
- University of Iceland, Department of Chemistry, Science Institute, Dunhaga 3, 107 Reykjavik, Iceland.
| | - Frederic Mentink-Vigier
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32301, USA.
| | - Gaël De Paëpe
- Univ. Grenoble Alpes, CEA, CNRS, IRIG, MEM, 38000 Grenoble, France.
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8
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Paul S, Bouleau E, Reynard-Feytis Q, Arnaud JP, Bancel F, Rollet B, Dalban-Moreynas P, Reiter C, Purea A, Engelke F, Hediger S, De Paëpe G. Sustainable and cost-effective MAS DNP-NMR at 30 K with cryogenic sample exchange. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2023; 356:107561. [PMID: 37837749 DOI: 10.1016/j.jmr.2023.107561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 09/18/2023] [Accepted: 09/22/2023] [Indexed: 10/16/2023]
Abstract
We report here instrumental developments to achieve sustainable, cost-effective cryogenic Helium sample spinning in order to conduct dynamic nuclear polarisation (DNP) and solid-state NMR (ssNMR) at ultra-low temperatures (<30 K). More specifically, we describe an efficient closed-loop helium system composed of a powerful heat exchanger (95% efficient), a single cryocooler, and a single helium compressor to power the sample spinning and cooling. The system is integrated with a newly designed triple-channel NMR probe that minimizes thermal losses without compromising the radio frequency (RF) performance and spinning stability (±0.05%). The probe is equipped with an innovative cryogenic sample exchange system that allows swapping samples in minutes without introducing impurities in the closeloop system. We report that significant gain in sensitivity can be obtained at 30-40 K on large micro-crystalline molecules with unfavorable relaxation timescales, making them difficult or impossible to polarize at 100 K. We also report rotor-synchronized 2D experiments to demonstrate the stability of the system.
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Affiliation(s)
- Subhradip Paul
- Univ. Grenoble. Alpes, CEA, CNRS, IRIG, MEM, 38000 Grenoble, France
| | - Eric Bouleau
- Univ. Grenoble Alpes, CEA, IRIG, DSBT, 38000 Grenoble, France
| | | | | | - Florian Bancel
- Univ. Grenoble Alpes, CEA, IRIG, DSBT, 38000 Grenoble, France
| | - Bertrand Rollet
- Univ. Grenoble Alpes, CEA, IRIG, DSBT, 38000 Grenoble, France
| | | | | | | | | | - Sabine Hediger
- Univ. Grenoble. Alpes, CEA, CNRS, IRIG, MEM, 38000 Grenoble, France
| | - Gaël De Paëpe
- Univ. Grenoble. Alpes, CEA, CNRS, IRIG, MEM, 38000 Grenoble, France.
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9
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Pillai A, Elanchezhian M, Virtanen T, Conti S, Ajoy A. Electron-to-nuclear spectral mapping via dynamic nuclear polarization. J Chem Phys 2023; 159:154201. [PMID: 37843056 DOI: 10.1063/5.0157954] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Accepted: 08/08/2023] [Indexed: 10/17/2023] Open
Abstract
We report on a strategy to indirectly read out the spectrum of an electronic spin via polarization transfer to nuclear spins in its local environment. The nuclear spins are far more abundant and have longer lifetimes, allowing for repeated polarization accumulation in them. Subsequent nuclear interrogation can reveal information about the electronic spectral density of states. We experimentally demonstrate the method by reading out the ESR spectrum of nitrogen vacancy center electrons in diamond via readout of lattice 13C nuclei. Spin-lock control on the 13C nuclei yields a significantly enhanced signal-to-noise ratio for the nuclear readout. Spectrally mapped readout presents operational advantages in being background-free and immune to crystal orientation and optical scattering. We harness these advantages to demonstrate applications in underwater magnetometry. The physical basis for the "one-to-many" spectral map is itself intriguing. To uncover its origin, we develop a theoretical model that maps the system dynamics, involving traversal of a cascaded structure of Landau-Zener anti-crossings, to the operation of a tilted "Galton board." This work points to new opportunities for "ESR-via-NMR" in dilute electronic systems and in hybrid electron-nuclear quantum memories and sensors.
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Affiliation(s)
- Arjun Pillai
- Department of Chemistry, University of California Berkeley, Berkeley, California 94720, USA
| | - Moniish Elanchezhian
- Department of Chemistry, University of California Berkeley, Berkeley, California 94720, USA
| | - Teemu Virtanen
- Department of Chemistry, University of California Berkeley, Berkeley, California 94720, USA
| | - Sophie Conti
- Department of Chemistry, University of California Berkeley, Berkeley, California 94720, USA
| | - Ashok Ajoy
- Department of Chemistry, University of California Berkeley, Berkeley, California 94720, USA
- Lawrence Berkeley National Laboratory, Chemical Sciences Division, Berkeley, California 94720, USA
- CIFAR Azrieli Global Scholars Program, 661 University Ave, Toronto, ON M5G 1M1, Canada
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10
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Menzildjian G, Schlagnitweit J, Casano G, Ouari O, Gajan D, Lesage A. Polarizing agents for efficient high field DNP solid-state NMR spectroscopy under magic-angle spinning: from design principles to formulation strategies. Chem Sci 2023; 14:6120-6148. [PMID: 37325158 PMCID: PMC10266460 DOI: 10.1039/d3sc01079a] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 05/09/2023] [Indexed: 06/17/2023] Open
Abstract
Dynamic Nuclear Polarization (DNP) has recently emerged as a cornerstone approach to enhance the sensitivity of solid-state NMR spectroscopy under Magic Angle Spinning (MAS), opening unprecedented analytical opportunities in chemistry and biology. DNP relies on a polarization transfer from unpaired electrons (present in endogenous or exogenous polarizing agents) to nearby nuclei. Developing and designing new polarizing sources for DNP solid-state NMR spectroscopy is currently an extremely active research field per se, that has recently led to significant breakthroughs and key achievements, in particular at high magnetic fields. This review describes recent developments in this area, highlighting key design principles that have been established over time and led to the introduction of increasingly more efficient polarizing sources. After a short introduction, Section 2 presents a brief history of solid-state DNP, highlighting the main polarization transfer schemes. The third section is devoted to the development of dinitroxide radicals, discussing the guidelines that were progressively established to design the fine-tuned molecular structures in use today. In Section 4, we describe recent efforts in developing hybrid radicals composed of a narrow EPR line radical covalently linked to a nitroxide, highlighting the parameters that modulate the DNP efficiency of these mixed structures. Section 5 reviews recent advances in the design of metal complexes suitable for DNP MAS NMR as exogenous electron sources. In parallel, current strategies that exploit metal ions as endogenous polarization sources are discussed. Section 6 briefly describes the recent introduction of mixed-valence radicals. In the last part, experimental aspects regarding sample formulation are reviewed to make best use of these polarizing agents in a broad panel of application fields.
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Affiliation(s)
- Georges Menzildjian
- Centre de RMN à, Très Hauts Champs, Université de Lyon (CNRS/ENS Lyon/UCB Lyon 1) 5 Rue de la doua 69100 Villeurbanne France
| | - Judith Schlagnitweit
- Centre de RMN à, Très Hauts Champs, Université de Lyon (CNRS/ENS Lyon/UCB Lyon 1) 5 Rue de la doua 69100 Villeurbanne France
| | - Gilles Casano
- Aix Marseille Univ., CNRS, Institut de Chimie Radicalaire, UMR 7273 Marseille France
| | - Olivier Ouari
- Aix Marseille Univ., CNRS, Institut de Chimie Radicalaire, UMR 7273 Marseille France
| | - David Gajan
- Centre de RMN à, Très Hauts Champs, Université de Lyon (CNRS/ENS Lyon/UCB Lyon 1) 5 Rue de la doua 69100 Villeurbanne France
| | - Anne Lesage
- Centre de RMN à, Très Hauts Champs, Université de Lyon (CNRS/ENS Lyon/UCB Lyon 1) 5 Rue de la doua 69100 Villeurbanne France
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11
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Dervişoğlu R, Antonschmidt L, Nimerovsky E, Sant V, Kim M, Ryazanov S, Leonov A, Carlos Fuentes-Monteverde J, Wegstroth M, Giller K, Mathies G, Giese A, Becker S, Griesinger C, Andreas LB. Anle138b interaction in α-synuclein aggregates by dynamic nuclear polarization NMR. Methods 2023; 214:18-27. [PMID: 37037308 DOI: 10.1016/j.ymeth.2023.04.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 03/22/2023] [Accepted: 04/06/2023] [Indexed: 04/12/2023] Open
Abstract
Small molecules that bind to oligomeric protein species such as membrane proteins and fibrils are of clinical interest for development of therapeutics and diagnostics. Definition of the binding site at atomic resolution via NMR is often challenging due to low binding stoichiometry of the small molecule. For fibrils and aggregation intermediates grown in the presence of lipids, we report atomic-resolution contacts to the small molecule at sub nm distance via solid-state NMR using dynamic nuclear polarization (DNP) and orthogonally labelled samples of the protein and the small molecule. We apply this approach to α-synuclein (αS) aggregates in complex with the small molecule anle138b, which is a clinical drug candidate for disease modifying therapy. The small central pyrazole moiety of anle138b is detected in close proximity to the protein backbone and differences in the contacts between fibrils and early intermediates are observed. For intermediate species, the 100 K condition for DNP helps to preserve the aggregation state, while for both fibrils and oligomers, the DNP enhancement is essential to obtain sufficient sensitivity.
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Affiliation(s)
- Rıza Dervişoğlu
- Department of NMR based structural Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Leif Antonschmidt
- Department of NMR based structural Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Evgeny Nimerovsky
- Department of NMR based structural Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Vrinda Sant
- Department of NMR based structural Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Myeongkyu Kim
- Department of NMR based structural Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Sergey Ryazanov
- Department of NMR based structural Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany; Center for Neuropathology and Prion Research, Ludwig-Maximilians University, Munich, Germany
| | - Andrei Leonov
- Department of NMR based structural Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany; Center for Neuropathology and Prion Research, Ludwig-Maximilians University, Munich, Germany
| | | | - Melanie Wegstroth
- Department of NMR based structural Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Karin Giller
- Department of NMR based structural Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | | | - Armin Giese
- Center for Neuropathology and Prion Research, Ludwig-Maximilians University, Munich, Germany
| | - Stefan Becker
- Department of NMR based structural Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Christian Griesinger
- Department of NMR based structural Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany; Cluster of Excellence "Multiscale Bioimaging: From Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany
| | - Loren B Andreas
- Department of NMR based structural Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.
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12
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Thomas B, Jardón-Álvarez D, Carmieli R, van Tol J, Leskes M. The Effect of Disorder on Endogenous MAS-DNP: Study of Silicate Glasses and Crystals. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2023; 127:4759-4772. [PMID: 36925559 PMCID: PMC10009812 DOI: 10.1021/acs.jpcc.2c08849] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/18/2022] [Revised: 02/05/2023] [Indexed: 06/18/2023]
Abstract
In dynamic nuclear polarization nuclear magnetic resonance (DNP-NMR) experiments, the large Boltzmann polarization of unpaired electrons is transferred to surrounding nuclei, leading to a significant increase in the sensitivity of the NMR signal. In order to obtain large polarization gains in the bulk of inorganic samples, paramagnetic metal ions are introduced as minor dopants acting as polarizing agents. While this approach has been shown to be very efficient in crystalline inorganic oxides, significantly lower enhancements have been reported when applying this approach to oxide glasses. In order to rationalize the origin of the difference in the efficiency of DNP in amorphous and crystalline inorganic matrices, we performed a detailed comparison in terms of their magnetic resonance properties. To diminish differences in the DNP performance arising from distinct nuclear interactions, glass and crystal systems of similar compositions were chosen, Li2OCaO·2SiO2 and Li2CaSiO4, respectively. Using Gd(III) as polarizing agent, DNP provided signal enhancements in the range of 100 for the crystalline sample, while only up to around factor 5 in the glass, for both 6Li and 29Si nuclei. We find that the drop in enhancement in glasses can be attributed to three main factors: shorter nuclear and electron relaxation times as well as the dielectric properties of glass and crystal. The amorphous nature of the glass sample is responsible for a high dielectric loss, leading to efficient microwave absorption and consequently lower effective microwave power and an increase in sample temperature which leads to further reduction of the electron relaxation time. These results help rationalize the observed sensitivity enhancements and provide guidance in identifying materials that could benefit from the DNP approach.
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Affiliation(s)
- Brijith Thomas
- Department
of Molecular Chemistry & Materials Science, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Daniel Jardón-Álvarez
- Department
of Molecular Chemistry & Materials Science, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Raanan Carmieli
- Department
of Chemical Research Support, Weizmann Institute
of Science, Rehovot 76100, Israel
| | - Johan van Tol
- National
High Magnetic Field Laboratory, Florida
State University, Tallahassee, Florida 32310, United States
| | - Michal Leskes
- Department
of Molecular Chemistry & Materials Science, Weizmann Institute of Science, Rehovot 76100, Israel
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13
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Eills J, Budker D, Cavagnero S, Chekmenev EY, Elliott SJ, Jannin S, Lesage A, Matysik J, Meersmann T, Prisner T, Reimer JA, Yang H, Koptyug IV. Spin Hyperpolarization in Modern Magnetic Resonance. Chem Rev 2023; 123:1417-1551. [PMID: 36701528 PMCID: PMC9951229 DOI: 10.1021/acs.chemrev.2c00534] [Citation(s) in RCA: 64] [Impact Index Per Article: 64.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Indexed: 01/27/2023]
Abstract
Magnetic resonance techniques are successfully utilized in a broad range of scientific disciplines and in various practical applications, with medical magnetic resonance imaging being the most widely known example. Currently, both fundamental and applied magnetic resonance are enjoying a major boost owing to the rapidly developing field of spin hyperpolarization. Hyperpolarization techniques are able to enhance signal intensities in magnetic resonance by several orders of magnitude, and thus to largely overcome its major disadvantage of relatively low sensitivity. This provides new impetus for existing applications of magnetic resonance and opens the gates to exciting new possibilities. In this review, we provide a unified picture of the many methods and techniques that fall under the umbrella term "hyperpolarization" but are currently seldom perceived as integral parts of the same field. Specifically, before delving into the individual techniques, we provide a detailed analysis of the underlying principles of spin hyperpolarization. We attempt to uncover and classify the origins of hyperpolarization, to establish its sources and the specific mechanisms that enable the flow of polarization from a source to the target spins. We then give a more detailed analysis of individual hyperpolarization techniques: the mechanisms by which they work, fundamental and technical requirements, characteristic applications, unresolved issues, and possible future directions. We are seeing a continuous growth of activity in the field of spin hyperpolarization, and we expect the field to flourish as new and improved hyperpolarization techniques are implemented. Some key areas for development are in prolonging polarization lifetimes, making hyperpolarization techniques more generally applicable to chemical/biological systems, reducing the technical and equipment requirements, and creating more efficient excitation and detection schemes. We hope this review will facilitate the sharing of knowledge between subfields within the broad topic of hyperpolarization, to help overcome existing challenges in magnetic resonance and enable novel applications.
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Affiliation(s)
- James Eills
- Institute
for Bioengineering of Catalonia, Barcelona
Institute of Science and Technology, 08028Barcelona, Spain
| | - Dmitry Budker
- Johannes
Gutenberg-Universität Mainz, 55128Mainz, Germany
- Helmholtz-Institut,
GSI Helmholtzzentrum für Schwerionenforschung, 55128Mainz, Germany
- Department
of Physics, UC Berkeley, Berkeley, California94720, United States
| | - Silvia Cavagnero
- Department
of Chemistry, University of Wisconsin, Madison, Madison, Wisconsin53706, United States
| | - Eduard Y. Chekmenev
- Department
of Chemistry, Integrative Biosciences (IBio), Karmanos Cancer Institute
(KCI), Wayne State University, Detroit, Michigan48202, United States
- Russian
Academy of Sciences, Moscow119991, Russia
| | - Stuart J. Elliott
- Molecular
Sciences Research Hub, Imperial College
London, LondonW12 0BZ, United Kingdom
| | - Sami Jannin
- Centre
de RMN à Hauts Champs de Lyon, Université
de Lyon, CNRS, ENS Lyon, Université Lyon 1, 69100Villeurbanne, France
| | - Anne Lesage
- Centre
de RMN à Hauts Champs de Lyon, Université
de Lyon, CNRS, ENS Lyon, Université Lyon 1, 69100Villeurbanne, France
| | - Jörg Matysik
- Institut
für Analytische Chemie, Universität
Leipzig, Linnéstr. 3, 04103Leipzig, Germany
| | - Thomas Meersmann
- Sir
Peter Mansfield Imaging Centre, University Park, School of Medicine, University of Nottingham, NottinghamNG7 2RD, United Kingdom
| | - Thomas Prisner
- Institute
of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic
Resonance, Goethe University Frankfurt, , 60438Frankfurt
am Main, Germany
| | - Jeffrey A. Reimer
- Department
of Chemical and Biomolecular Engineering, UC Berkeley, and Materials Science Division, Lawrence Berkeley National
Laboratory, Berkeley, California94720, United States
| | - Hanming Yang
- Department
of Chemistry, University of Wisconsin, Madison, Madison, Wisconsin53706, United States
| | - Igor V. Koptyug
- International Tomography Center, Siberian
Branch of the Russian Academy
of Sciences, 630090Novosibirsk, Russia
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14
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Smith AN, Harrabi R, Halbritter T, Lee D, Aussenac F, van der Wel PCA, Hediger S, Sigurdsson ST, De Paëpe G. Fast magic angle spinning for the characterization of milligram quantities of organic and biological solids at natural isotopic abundance by 13C- 13C correlation DNP-enhanced NMR. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2023; 123:101850. [PMID: 36592488 DOI: 10.1016/j.ssnmr.2022.101850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 11/25/2022] [Accepted: 12/13/2022] [Indexed: 06/17/2023]
Abstract
We show that multidimensional solid-state NMR 13C-13C correlation spectra of biomolecular assemblies and microcrystalline organic molecules can be acquired at natural isotopic abundance with only milligram quantities of sample. These experiments combine fast Magic Angle Spinning of the sample, low-power dipolar recoupling, and dynamic nuclear polarization performed with AsymPol biradicals, a recently introduced family of polarizing agents. Such experiments are essential for structural characterization as they provide short- and long-range distance information. This approach is demonstrated on diverse sample types, including polyglutamine fibrils implicated in Huntington's disease and microcrystalline ampicillin, a small antibiotic molecule.
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Affiliation(s)
- Adam N Smith
- Univ. Grenoble Alpes, CEA, CNRS, IRIG, MEM, 38000, Grenoble, France
| | - Rania Harrabi
- Univ. Grenoble Alpes, CEA, CNRS, IRIG, MEM, 38000, Grenoble, France
| | - Thomas Halbritter
- University of Iceland, Department of Chemistry, Science Institute, Dunhaga 3, 107, Reykjavik, Iceland
| | - Daniel Lee
- Univ. Grenoble Alpes, CEA, CNRS, IRIG, MEM, 38000, Grenoble, France
| | | | - Patrick C A van der Wel
- Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, Netherlands
| | - Sabine Hediger
- Univ. Grenoble Alpes, CEA, CNRS, IRIG, MEM, 38000, Grenoble, France
| | - Snorri Th Sigurdsson
- University of Iceland, Department of Chemistry, Science Institute, Dunhaga 3, 107, Reykjavik, Iceland
| | - Gaël De Paëpe
- Univ. Grenoble Alpes, CEA, CNRS, IRIG, MEM, 38000, Grenoble, France.
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15
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Tagami K, Thicklin R, Jain S, Equbal A, Li M, Zens T, Siaw A, Han S. Design of a cryogen-free high field dual EPR and DNP probe. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2023; 347:107351. [PMID: 36599253 DOI: 10.1016/j.jmr.2022.107351] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 11/29/2022] [Accepted: 11/30/2022] [Indexed: 06/17/2023]
Abstract
We present the design and construction of a cryogen free, dual electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR) probe for novel dynamic nuclear polarization (DNP) experiments and concurrent "in situ" analysis of DNP mechanisms. We focus on the probe design that meets the balance between EPR, NMR, and low temperature performance, while maintaining a high degree of versatility: allowing multi-nuclear NMR detection as well as broadband DNP/EPR excitation/detection. To accomplish high NMR/EPR performance, we implement a novel inductively coupled double resonance NMR circuit (1H-13C) in a solid state probe operating at cryogenic temperatures. The components of the circuit were custom built to provide maximum NMR performance, and the physical layout of this circuit was numerically optimized via magnetic field simulations to allow maximum microwave transmission to the sample for optimal EPR performance. Furthermore this probe is based around a cryogen free gas exchange cryostat and has been designed to allow unlimited experiment times down to 8.5 Kelvin with minimal cost. The affordability of EPR/DNP experiment is an extremely important aspect for broader impact with magnetic resonance measurements. The purpose of this article is to provide as complete information as we have available for others with interest in building a dual DNP/EPR instrument based around a cryogen-free cryostat.
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Affiliation(s)
- Kan Tagami
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, CA 93106, United States
| | - Raymond Thicklin
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, CA 93106, United States
| | - Sheetal Jain
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, CA 93106, United States
| | - Asif Equbal
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, CA 93106, United States
| | - Miranda Li
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, CA 93106, United States
| | - Toby Zens
- JEOL USA, Inc., 11 Dearborn Road, Peabody, MA 01960, United States
| | - Anthony Siaw
- JEOL USA, Inc., 11 Dearborn Road, Peabody, MA 01960, United States
| | - Songi Han
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, CA 93106, United States; Department of Chemical Engineering, University of California, Santa Barbara, Santa Barbara, CA 93106, United States.
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16
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Gan Z. An analytical treatment of electron spectral saturation for dynamic nuclear polarization NMR of rotating solids. J Chem Phys 2023; 158:024114. [PMID: 36641384 DOI: 10.1063/5.0109077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Saturation of electron magnetization by microwave irradiation under magic-angle spinning (MAS) is studied theoretically. The saturation is essential for dynamic nuclear polarization (DNP) enhancement of nuclear magnetic resonance signals. For a spin with a large g-anisotropy and a long T1 relative to the rotor period, the sample rotation distributes saturation to the whole powder sample spectrum. Analytical expressions for the saturation and frequency profiles are obtained. For a pair of coupled electrons such as those in bis-nitroxides, which are commonly used for MAS DNP, an el-er model (where el and er stand for electrons on the left and the right, respectively, in their spectral positions) is introduced to simplify the analysis of a coupled two-spin system under MAS. For such a system, strong electron couplings exchange magnetization during dipolar/J rotor events when the two electron frequencies cross each other. The exchange is equivalent to a swap of the el and er electrons. This allows for the treatment of a coupled spin pair as two independent spins such that an analytical solution can be obtained for the steady-state magnetization and the difference between the two electrons. The theoretical study with its analytical result provides a simple physical picture of electron saturation under MAS and of how radical properties and experimental parameters affect cross-effect DNP. The effects of depolarization and the extension to more coupled electron spins are also discussed using this approach.
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Affiliation(s)
- Zhehong Gan
- National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, USA
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17
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Döller SC, Gutmann T, Hoffmann M, Buntkowsky G. A case study on the influence of hydrophilicity on the signal enhancement by dynamic nuclear polarization. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2022; 122:101829. [PMID: 36116176 DOI: 10.1016/j.ssnmr.2022.101829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 08/25/2022] [Accepted: 09/07/2022] [Indexed: 06/15/2023]
Abstract
In this work, the behavior of four different commercially available polarizing agents is investigated employing the non-ionic model surfactant 1-octanol as analyte. A relative method for the comparison of the proportion of the direct and indirect polarization transfer pathways is established, allowing a direct comparison of the polarization efficacy for different radicals and different parts of the 1-octanol molecule despite differences in radical concentration or sample amount. With this approach, it could be demonstrated that the hydrophilicity is a key factor in the way polarization is transferred from the polarizing agent to the analyte. These findings are confirmed by the determination of buildup times Tb, illustrating that the choice of polarizing agent plays an essential role in ensuring an optimal polarization transfer and therefore the maximum amount of enhancement possible for DNP enhanced NMR measurements.
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Affiliation(s)
- Sonja C Döller
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Technische Universität Darmstadt, Alarich-Weiss-Str. 8, D-64287, Darmstadt, Germany
| | - Torsten Gutmann
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Technische Universität Darmstadt, Alarich-Weiss-Str. 8, D-64287, Darmstadt, Germany
| | - Markus Hoffmann
- Department of Chemistry and Biochemistry, State University of New York College at Brockport, Brockport, NY, 14420, USA
| | - Gerd Buntkowsky
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Technische Universität Darmstadt, Alarich-Weiss-Str. 8, D-64287, Darmstadt, Germany.
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18
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Pang Z, Jain S, Yang C, Kong X, Tan KO. A unified description for polarization-transfer mechanisms in magnetic resonance in static solids: Cross polarization and DNP. J Chem Phys 2022; 156:244109. [DOI: 10.1063/5.0092265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Polarization transfers are crucial building blocks in magnetic resonance experiments, i.e., they can be used to polarize insensitive nuclei and correlate nuclear spins in multidimensional nuclear magnetic resonance (NMR) spectroscopy. The polarization can be transferred either across different nuclear spin species or from electron spins to the relatively low-polarized nuclear spins. The former route occurring in solid-state NMR can be performed via cross polarization (CP), while the latter route is known as dynamic nuclear polarization (DNP). Despite having different operating conditions, we opinionate that both mechanisms are theoretically similar processes in ideal conditions, i.e., the electron is merely another spin-1/2 particle with a much higher gyromagnetic ratio. Here, we show that the CP and DNP processes can be described using a unified theory based on average Hamiltonian theory combined with fictitious operators. The intuitive and unified approach has allowed new insights into the cross-effect DNP mechanism, leading to better design of DNP polarizing agents and extending the applications beyond just hyperpolarization. We explore the possibility of exploiting theoretically predicted DNP transients for electron–nucleus distance measurements—such as routine dipolar-recoupling experiments in solid-state NMR.
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Affiliation(s)
- Zhenfeng Pang
- Department of Chemistry, Zhejiang University, 310027 Hangzhou, China
- Laboratoire des Biomolécules, LBM, Département de Chimie, École Normale Supérieure, PSL University, Sorbonne Université, CNRS, 75005 Paris, France
| | - Sheetal Jain
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India
| | - Chen Yang
- Amazon Robotics, 300 Riverpark Drive, North Reading, Massachusetts 01864, USA
| | - Xueqian Kong
- Department of Chemistry, Zhejiang University, 310027 Hangzhou, China
| | - Kong Ooi Tan
- Laboratoire des Biomolécules, LBM, Département de Chimie, École Normale Supérieure, PSL University, Sorbonne Université, CNRS, 75005 Paris, France
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19
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Deligey F, Frank MA, Cho SH, Kirui A, Mentink-Vigier F, Swulius MT, Nixon BT, Wang T. Structure of In Vitro-Synthesized Cellulose Fibrils Viewed by Cryo-Electron Tomography and 13C Natural-Abundance Dynamic Nuclear Polarization Solid-State NMR. Biomacromolecules 2022; 23:2290-2301. [PMID: 35341242 PMCID: PMC9198983 DOI: 10.1021/acs.biomac.1c01674] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 03/16/2022] [Indexed: 12/25/2022]
Abstract
Cellulose, the most abundant biopolymer, is a central source for renewable energy and functionalized materials. In vitro synthesis of cellulose microfibrils (CMFs) has become possible using purified cellulose synthase (CESA) isoforms from Physcomitrium patens and hybrid aspen. The exact nature of these in vitro fibrils remains unknown. Here, we characterize in vitro-synthesized fibers made by CESAs present in membrane fractions of P. patens over-expressing CESA5 by cryo-electron tomography and dynamic nuclear polarization (DNP) solid-state NMR. DNP enabled measuring two-dimensional 13C-13C correlation spectra without isotope-labeling of the fibers. Results show structural similarity between in vitro fibrils and native CMF in plant cell walls. Intensity quantifications agree with the 18-chain structural model for plant CMF and indicate limited fibrillar bundling. The in vitro system thus reveals insights into cell wall synthesis and may contribute to novel cellulosic materials. The integrated DNP and cryo-electron tomography methods are also applicable to structural studies of other carbohydrate-based biomaterials.
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Affiliation(s)
- Fabien Deligey
- Department
of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Mark A. Frank
- Department
of Biochemistry and Molecular Biology, Pennsylvania
State University, University
Park, Pennsylvania 16802, United States
| | - Sung Hyun Cho
- Department
of Biochemistry and Molecular Biology, Pennsylvania
State University, University
Park, Pennsylvania 16802, United States
| | - Alex Kirui
- Department
of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | | | - Matthew T. Swulius
- Department
of Biochemistry and Molecular Biology, Pennsylvania
State University, Hershey, Pennsylvania 17033, United States
| | - B. Tracy Nixon
- Department
of Biochemistry and Molecular Biology, Pennsylvania
State University, University
Park, Pennsylvania 16802, United States
| | - Tuo Wang
- Department
of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
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20
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Perras FA, Flesariu DF, Southern SA, Nicolaides C, Bazak JD, Washton NM, Trypiniotis T, Constantinides CP, Koutentis PA. Methyl-Driven Overhauser Dynamic Nuclear Polarization. J Phys Chem Lett 2022; 13:4000-4006. [PMID: 35482607 DOI: 10.1021/acs.jpclett.2c00748] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The Overhauser effect is unique among DNP mechanisms in that it requires the modulation of the electron-nuclear hyperfine interactions. While it dominates DNP in liquids and metals, where unpaired electrons are highly mobile, Overhauser DNP is possible in insulating solids if rapid structural modulations are linked to a modulation in hyperfine coupling. Herein, we report that Overhauser DNP can be triggered by the strategic addition of a methyl group, demonstrated here in a Blatter's radical. The rotation of the methyl group leads to a modulation of the hyperfine coupling to its protons, which in turn facilitates electron-nuclear cross-relaxation. Removal of the methyl protons, through deuteration, quenches the process, as does the reduction of the hyperfine coupling strength. This result suggests the possibility for the design of tailor-made Overhauser DNP polarizing agents for high-field MAS-DNP.
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Affiliation(s)
| | - Dragos F Flesariu
- Department of Chemistry, University of Cyprus, P.O. Box 20537, 1678 Nicosia, Cyprus
| | | | | | - J David Bazak
- Physical & Computational Science Directorate, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Nancy M Washton
- Physical & Computational Science Directorate, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | | | - Christos P Constantinides
- Department of Natural Sciences, University of Michigan-Dearborn, 4901 Evergreen Road, Dearborn, Michigan 48128-1491, United States
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21
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Kundu K, Dubroca T, Rane V, Mentink-Vigier F. Spinning-Driven Dynamic Nuclear Polarization with Optical Pumping. J Phys Chem A 2022; 126:2600-2608. [PMID: 35417169 PMCID: PMC9121629 DOI: 10.1021/acs.jpca.2c01559] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
We propose a new, more efficient, and potentially cost effective, solid-state nuclear spin hyperpolarization method combining the cross-effect mechanism and electron spin optical hyperpolarization in rotating solids. We first demonstrate optical hyperpolarization in the solid state at low temperatures and low field and then investigate its field dependence to obtain the optimal condition for high-field electron spin hyperpolarization. The results are then incorporated into advanced magic-angle spinning dynamic nuclear polarization (MAS-DNP) numerical simulations that show that optically pumped MAS-DNP could yield breakthrough enhancements at very high magnetic fields. Based on these investigations, enhancements greater than the ratio of electron to nucleus magnetic moments (>658 for 1H) are possible without microwave irradiation. This could solve at once the MAS-DNP performance decrease with increasing field and the high cost of MAS-DNP instruments at very high fields.
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Affiliation(s)
- Krishnendu Kundu
- National High Magnetic Field Laboratory, Florida State University, 1800 E Paul Dirac Drive, Tallahassee, Florida 32310, United States
| | - Thierry Dubroca
- National High Magnetic Field Laboratory, Florida State University, 1800 E Paul Dirac Drive, Tallahassee, Florida 32310, United States
| | - Vinayak Rane
- Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
| | - Frederic Mentink-Vigier
- National High Magnetic Field Laboratory, Florida State University, 1800 E Paul Dirac Drive, Tallahassee, Florida 32310, United States
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22
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Perras FA, Carnahan SL, Lo WS, Ward CJ, Yu J, Huang W, Rossini AJ. Hybrid quantum-classical simulations of magic angle spinning dynamic nuclear polarization in very large spin systems. J Chem Phys 2022; 156:124112. [DOI: 10.1063/5.0086530] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Solid-state nuclear magnetic resonance can be enhanced using unpaired electron spins with a method known as dynamic nuclear polarization (DNP). Fundamentally, DNP involves ensembles of thousands of spins, a scale that is difficult to match computationally. This scale prevents us from gaining a complete understanding of the spin dynamics and applying simulations to design sample formulations. We recently developed an ab initio model capable of calculating DNP enhancements in systems of up to ∼1000 nuclei; however, this scale is insufficient to accurately simulate the dependence of DNP enhancements on radical concentration or magic angle spinning (MAS) frequency. We build on this work by using ab initio simulations to train a hybrid model that makes use of a rate matrix to treat nuclear spin diffusion. We show that this model can reproduce the MAS rate and concentration dependence of DNP enhancements and build-up time constants. We then apply it to predict the DNP enhancements in core–shell metal-organic-framework nanoparticles and reveal new insights into the composition of the particles’ shells.
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Affiliation(s)
| | - Scott L. Carnahan
- Ames Laboratory, U.S. DOE, Ames, Iowa 50011, USA
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA
| | - Wei-Shang Lo
- Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467, USA
| | - Charles J. Ward
- Ames Laboratory, U.S. DOE, Ames, Iowa 50011, USA
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA
| | - Jiaqi Yu
- Ames Laboratory, U.S. DOE, Ames, Iowa 50011, USA
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA
| | - Wenyu Huang
- Ames Laboratory, U.S. DOE, Ames, Iowa 50011, USA
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA
| | - Aaron J. Rossini
- Ames Laboratory, U.S. DOE, Ames, Iowa 50011, USA
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA
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23
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Wi S, Dwivedi N, Dubey R, Mentink-Vigier F, Sinha N. Dynamic nuclear polarization-enhanced, double-quantum filtered 13C- 13C dipolar correlation spectroscopy of natural 13C abundant bone-tissue biomaterial. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2022; 335:107144. [PMID: 35085899 PMCID: PMC8823282 DOI: 10.1016/j.jmr.2022.107144] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Revised: 01/07/2022] [Accepted: 01/08/2022] [Indexed: 05/03/2023]
Abstract
Here, we describe a method for obtaining a dynamic nuclear polarization (DNP)-enhanced double-quantum filtered (DQF) two-dimensional (2D) dipolar 13C-13C correlation spectra of bone-tissue material at natural 13C abundance. DNP-enhanced DQF 2D dipolar 13C-13C spectra were obtained using a few different mixing times of the dipolar-assisted rotational resonance (DARR) scheme and these spectra were compared to a conventional 2D through-space double-quantum (DQ)-single-quantum (SQ) correlation spectrum. While this scheme can only be used for an assignment purpose to reveal the carbon-carbon connectivity within a residue, the DQF 13C-13C dipolar correlation scheme introduced here can be used to obtain longer distance carbon-carbon constraints. A DQF pulse block is placed before the DARR mixing scheme for removing dominant 13C single-quantum (SQ) signals because these SQ 13C signals are overwhelmingly large compared to those 13C-13C dipolar cross-peaks generated and therefore saturate the dynamic range of the NMR detection. This approach exhibits strong enough 2D cross-peaks in a dipolar 13C-13C correlation spectrum and potentially provides pairwise 13C-13C dipolar constraints because the dipolar truncation effect as well as multi-step signal propagations involving a spin cluster that contains more than two spins can be ignored probabilistically. To obtain fast signal averaging, AsymPolPOK was used to provide a short 1H DNP signal build-up time (1.3 s) and to expedite our MAS DNP NMR acquisitions while still maintaining a satisfactory DNP enhancement factor (ε = 50). Under long DARR mixing, a t1-noise-like artifact was observed at a site that possesses a large chemical shift anisotropy (CSA) and a few different strategies to address this problem were discussed.
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Affiliation(s)
- Sungsool Wi
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32304, USA.
| | - Navneet Dwivedi
- Department of Advanced Spectroscopy and Imaging, Centre of Biomedical Research, SGPGIMS Campus, Raebarelly Road, Lucknow 226014, India; Department of Physics, Integral University, Lucknow 226026, India
| | - Richa Dubey
- Department of Advanced Spectroscopy and Imaging, Centre of Biomedical Research, SGPGIMS Campus, Raebarelly Road, Lucknow 226014, India
| | - Frederic Mentink-Vigier
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32304, USA
| | - Neeraj Sinha
- Department of Advanced Spectroscopy and Imaging, Centre of Biomedical Research, SGPGIMS Campus, Raebarelly Road, Lucknow 226014, India
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Carbohydrate-aromatic interface and molecular architecture of lignocellulose. Nat Commun 2022; 13:538. [PMID: 35087039 PMCID: PMC8795156 DOI: 10.1038/s41467-022-28165-3] [Citation(s) in RCA: 66] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 01/10/2022] [Indexed: 12/12/2022] Open
Abstract
Plant cell walls constitute the majority of lignocellulosic biomass and serve as a renewable resource of biomaterials and biofuel. Extensive interactions between polysaccharides and the aromatic polymer lignin make lignocellulose recalcitrant to enzymatic hydrolysis, but this polymer network remains poorly understood. Here we interrogate the nanoscale assembly of lignocellulosic components in plant stems using solid-state nuclear magnetic resonance and dynamic nuclear polarization approaches. We show that the extent of glycan-aromatic association increases sequentially across grasses, hardwoods, and softwoods. Lignin principally packs with the xylan in a non-flat conformation via non-covalent interactions and partially binds the junction of flat-ribbon xylan and cellulose surface as a secondary site. All molecules are homogeneously mixed in softwoods; this unique feature enables water retention even around the hydrophobic aromatics. These findings unveil the principles of polymer interactions underlying the heterogeneous architecture of lignocellulose, which may guide the rational design of more digestible plants and more efficient biomass-conversion pathways. The plant biomass is a composite formed by a variety of polysaccharides and an aromatic polymer named lignin. Here, the authors use solid-state NMR spectroscopy to unveil the carbohydrate-aromatic interface that leads to the variable architecture of lignocellulose biomaterials.
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Yang C, Ooi Tan K, Griffin RG. DNPSOUP: A simulation software package for dynamic nuclear polarization. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2022; 334:107107. [PMID: 34894420 PMCID: PMC8819672 DOI: 10.1016/j.jmr.2021.107107] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Revised: 11/04/2021] [Accepted: 11/05/2021] [Indexed: 06/01/2023]
Abstract
Dynamic Nuclear Polarization Simulation Optimized with a Unified Propagator (DNPSOUP) is an open-source numerical software program that models spin dynamics for dynamic nuclear polarization (DNP). The software package utilizes a direct numerical approach using the inhomogeneous master equation to treat the time evolution of the spin density operator under coherent Hamiltonians and stochastic relaxation effects. Here we present the details of the theory behind the software, starting from the master equation, and arriving at characteristic operators for any section of density operator time-evolution. We then provide an overview of the DNPSOUP software architecture. The efficacy of the program is demonstrated by simulating DNP field profiles on small spin systems exploiting both continuous wave and time-domain DNP mechanisms. Examples include Zeeman field profiles for the solid effect, Overhauser effect, and cross effect, and microwave field profiles for NOVEL, off-resonance NOVEL, the integrated solid effect, the stretched solid effect, and TOP-DNP. The software should facilitate a better understanding of the DNP process, aid in the design of optimized DNP polarizing agents, and allow us to examine new pulsed DNP methods at conditions that are not currently experimentally accessible, especially at high magnetic fields with high-power microwave pulses.
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Affiliation(s)
- Chen Yang
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, United States; Aspen Technology, Inc., 20 Crosby Drive, Bedford, MA 01730, United States
| | - Kong Ooi Tan
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, United States; Laboratoire des Biomolécules, LBM, Département de Chimie, École Normale Supérieure, PSL University, Sorbonne Université, CNRS, 75005 Paris, France
| | - Robert G Griffin
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, United States.
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26
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Menzildjian G, Lund A, Yulikov M, Gajan D, Niccoli L, Karthikeyan G, Casano G, Jeschke G, Ouari O, Lelli M, Lesage A. Efficient Dynamic Nuclear Polarization up to 230 K with Hybrid BDPA-Nitroxide Radicals at a High Magnetic Field. J Phys Chem B 2021; 125:13329-13338. [PMID: 34818009 DOI: 10.1021/acs.jpcb.1c07307] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Pairing the spectral resolution provided by high magnetic fields at ambient temperature with the enhanced sensitivity offered by dynamic nuclear polarization (DNP) is a major goal of modern solid-state NMR spectroscopy, which will allow one to unlock ever-challenging applications. This study demonstrates that, by combining HyTEK2, a hybrid BDPA-nitroxide biradical polarizing agent, with ortho-terphenyl (OTP), a rigid DNP matrix, enhancement factors as high as 65 can be obtained at 230 K, 40 kHz magic angle spinning (MAS), and 18.8 T. The temperature dependence of the DNP enhancement and its behavior around the glass transition temperature (Tg) of the matrix is investigated by variable-temperature EPR measurements of the electron relaxation properties and numerical simulations. A correlation is suggested between the decrease in enhancement at the passage of the Tg and the concomitant drop of both transverse electron relaxation times in the biradical.
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Affiliation(s)
- Georges Menzildjian
- Centre de RMN à Très Hauts Champs, Université de Lyon (CNRS/ENS Lyon/UCBL), 69100 Villeurbanne, France
| | - Alicia Lund
- Centre de RMN à Très Hauts Champs, Université de Lyon (CNRS/ENS Lyon/UCBL), 69100 Villeurbanne, France
| | - Maxim Yulikov
- Department of Chemistry and Applied Biosciences, Eidgenössische Technische Hochschule Zürich, CH-8093 Zürich, Switzerland
| | - David Gajan
- Centre de RMN à Très Hauts Champs, Université de Lyon (CNRS/ENS Lyon/UCBL), 69100 Villeurbanne, France
| | - Lorenzo Niccoli
- Center of Magnetic Resonance (CERM), University of Florence, 50019 Sesto Fiorentino, Italy
| | - Ganesan Karthikeyan
- Aix Marseille Univ, CNRS, Institut de Chimie Radicalaire, 13013 Marseille, France
| | - Gilles Casano
- Aix Marseille Univ, CNRS, Institut de Chimie Radicalaire, 13013 Marseille, France
| | - Gunnar Jeschke
- Department of Chemistry and Applied Biosciences, Eidgenössische Technische Hochschule Zürich, CH-8093 Zürich, Switzerland
| | - Olivier Ouari
- Aix Marseille Univ, CNRS, Institut de Chimie Radicalaire, 13013 Marseille, France
| | - Moreno Lelli
- Center of Magnetic Resonance (CERM), University of Florence, 50019 Sesto Fiorentino, Italy
| | - Anne Lesage
- Centre de RMN à Très Hauts Champs, Université de Lyon (CNRS/ENS Lyon/UCBL), 69100 Villeurbanne, France
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Ghassemi N, Poulhazan A, Deligey F, Mentink-Vigier F, Marcotte I, Wang T. Solid-State NMR Investigations of Extracellular Matrixes and Cell Walls of Algae, Bacteria, Fungi, and Plants. Chem Rev 2021; 122:10036-10086. [PMID: 34878762 DOI: 10.1021/acs.chemrev.1c00669] [Citation(s) in RCA: 55] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Extracellular matrixes (ECMs), such as the cell walls and biofilms, are important for supporting cell integrity and function and regulating intercellular communication. These biomaterials are also of significant interest to the production of biofuels and the development of antimicrobial treatment. Solid-state nuclear magnetic resonance (ssNMR) and magic-angle spinning-dynamic nuclear polarization (MAS-DNP) are uniquely powerful for understanding the conformational structure, dynamical characteristics, and supramolecular assemblies of carbohydrates and other biomolecules in ECMs. This review highlights the recent high-resolution investigations of intact ECMs and native cells in many organisms spanning across plants, bacteria, fungi, and algae. We spotlight the structural principles identified in ECMs, discuss the current technical limitation and underexplored biochemical topics, and point out the promising opportunities enabled by the recent advances of the rapidly evolving ssNMR technology.
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Affiliation(s)
- Nader Ghassemi
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Alexandre Poulhazan
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States.,Department of Chemistry, Université du Québec à Montréal, Montreal H2X 2J6, Canada
| | - Fabien Deligey
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | | | - Isabelle Marcotte
- Department of Chemistry, Université du Québec à Montréal, Montreal H2X 2J6, Canada
| | - Tuo Wang
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
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Mentink-Vigier F. Numerical recipes for faster MAS-DNP simulations. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2021; 333:107106. [PMID: 34837803 PMCID: PMC8639796 DOI: 10.1016/j.jmr.2021.107106] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 11/05/2021] [Accepted: 11/07/2021] [Indexed: 05/11/2023]
Abstract
Numerical simulations of Magic Angle Spinning Dynamic Nuclear Polarization (MAS-DNP) have transformed the way the DNP process is understood in rotating samples. In 2012, two methods were concomitantly developed to simulate small spin systems (< 4 spin-1/2). The development of new polarizing agents, including those containing metal centers with S > 1/2, makes it necessary to further expand the numerical tools with minimal approximations that will help rationalize the experimental observations and build approximate models. In this paper, three strategies developed in the past five years are presented: an adaptive integration scheme, a hybrid Hilbert/Liouville formalism, and a method to truncate the Liouville space basis for periodic Hamiltonian. Each of these methods enable time savings ranging from a factor of 3 to > 100. We illustrate the code performance by reporting for the first time the MAS-DNP field profiles for "AMUPol", in which the couplings to the nitrogen nuclei are explicitly considered, as well as Cross-Effect MAS-DNP field profiles with two electrons spin 5/2 interacting with a nuclear spin 1/2.
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Affiliation(s)
- Frederic Mentink-Vigier
- National High Magnetic Field Laboratory, Florida State University, 1800 E. Paul Dirac Dr, FL 32310, USA.
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29
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Equbal A, Jain SK, Li Y, Tagami K, Wang X, Han S. Role of electron spin dynamics and coupling network in designing dynamic nuclear polarization. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2021; 126-127:1-16. [PMID: 34852921 DOI: 10.1016/j.pnmrs.2021.05.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2021] [Accepted: 05/22/2021] [Indexed: 06/13/2023]
Abstract
Dynamic nuclear polarization (DNP) has emerged as a powerful sensitivity booster of nuclear magnetic resonance (NMR) spectroscopy for the characterization of biological solids, catalysts and other functional materials, but is yet to reach its full potential. DNP transfers the high polarization of electron spins to nuclear spins using microwave irradiation as a perturbation. A major focus in DNP research is to improve its efficiency at conditions germane to solid-state NMR, at high magnetic fields and fast magic-angle spinning. In this review, we highlight three key strategies towards designing DNP experiments: time-domain "smart" microwave manipulation to optimize and/or modulate electron spin polarization, EPR detection under operational DNP conditions to decipher the underlying electron spin dynamics, and quantum mechanical simulations of coupled electron spins to gain microscopic insights into the DNP mechanism. These strategies are aimed at understanding and modeling the properties of the electron spin dynamics and coupling network. The outcome of these strategies is expected to be key to developing next-generation polarizing agents and DNP methods.
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Affiliation(s)
- Asif Equbal
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, CA 93106, United States
| | - Sheetal Kumar Jain
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, CA 93106, United States
| | - Yuanxin Li
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, CA 93106, United States
| | - Kan Tagami
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, CA 93106, United States
| | - Xiaoling Wang
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, CA 93106, United States; Department of Physics, University of California, Santa Barbara, Santa Barbara, CA 93106, United States
| | - Songi Han
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, CA 93106, United States; Department of Chemical Engineering, University of California, Santa Barbara, Santa Barbara, CA 93106, United States.
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30
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Mentink-Vigier F, Dubroca T, Van Tol J, Sigurdsson ST. The distance between g-tensors of nitroxide biradicals governs MAS-DNP performance: The case of the bTurea family. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2021; 329:107026. [PMID: 34246883 PMCID: PMC8316413 DOI: 10.1016/j.jmr.2021.107026] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2021] [Revised: 06/14/2021] [Accepted: 06/16/2021] [Indexed: 05/20/2023]
Abstract
Bis-nitroxide radicals are common polarizing agents (PA), used to enhance the sensitivity of solid-state NMR experiments via Magic Angle Spinning Dynamic Nuclear Polarization (MAS-DNP). These biradicals can increase the proton spin polarization through the Cross-Effect (CE) mechanism, which requires PAs with at least two unpaired electrons. The relative orientation of the bis-nitroxide moieties is critical to ensure efficient polarization transfer. Recently, we have defined a new quantity, the distance between g-tensors, that correlates the relative orientation of the nitroxides with the ability to polarize the surrounding nuclei. Here we analyse experimentally and theoretically a series of biradicals belonging to the bTurea family, namely bcTol, AMUPol and bcTol-M. They differ by the degree of substitution on the urea bridge that connects the two nitroxides. Using quantitative simulations developed for moderate MAS frequencies, we show that these modifications mostly affect the relative orientations of the nitroxide, i.e. the length and distribution of the distance between the g-tensors, that in turn impacts both the steady state nuclear polarization/depolarization as well as the build-up times. The doubly substituted urea bridge favours a large distance between the g-tensors, which enables bcTol-M to provide ∊on/off>200 at 14.1 T/600 MHz/395 GHz with build-up times of 3.8 s using a standard homogenous solution. The methodology described herein was used to show how the conformation of the spirocyclic rings flanking the nitroxide function in the recently described c- and o-HydrOPol affects the distance between the g-tensors and thereby polarization performance.
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Affiliation(s)
- Frédéric Mentink-Vigier
- National High Magnetic Field Laboratory, Florida State University, 1800 E. Paul Dirac Dr, Tallahassee, FL 32310, United States.
| | - Thierry Dubroca
- National High Magnetic Field Laboratory, Florida State University, 1800 E. Paul Dirac Dr, Tallahassee, FL 32310, United States
| | - Johan Van Tol
- National High Magnetic Field Laboratory, Florida State University, 1800 E. Paul Dirac Dr, Tallahassee, FL 32310, United States
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31
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Concilio MG, Soundararajan M, Frydman L, Kuprov I. High-field solution state DNP using cross-correlations. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2021; 326:106940. [PMID: 33865207 DOI: 10.1016/j.jmr.2021.106940] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Revised: 02/08/2021] [Accepted: 02/09/2021] [Indexed: 06/12/2023]
Abstract
At the magnetic fields of common NMR instruments, electron Zeeman frequencies are too high for efficient electron-nuclear dipolar cross-relaxation to occur in solution. The rate of that process fades with the electron Zeeman frequency as ω-2 - in the absence of isotropic hyperfine couplings, liquid state dynamic nuclear polarisation (DNP) in high-field magnets is therefore impractical. However, contact coupling and dipolar cross-relaxation are not the only mechanisms that can move electron magnetisation to nuclei in liquids: multiple cross-correlated (CC) relaxation processes also exist, involving various combinations of interaction tensor anisotropies. The rates of some of those processes have more favourable high-field behaviour than dipolar cross-relaxation, but due to the difficulty of their numerical - and particularly analytical - treatment, they remain largely uncharted. In this communication, we report analytical evaluation of every rotationally driven relaxation process in liquid state for 1e1n and 2e1n spin systems, as well as numerical optimisations of the steady-state DNP with respect to spin Hamiltonian parameters. A previously unreported cross-correlated DNP (CCDNP) mechanism was identified for the 2e1n system, involving multiple relaxation interference effects and inter-electron exchange coupling. Using simulations, we found realistic spin Hamiltonian parameters that yield stronger nuclear polarisation at high magnetic fields than dipolar cross-relaxation.
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Affiliation(s)
- Maria Grazia Concilio
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel; School of Chemistry, University of Southampton, Southampton, UK.
| | | | - Lucio Frydman
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel; National High Magnetic Field Laboratory, Tallahassee, FL, USA.
| | - Ilya Kuprov
- School of Chemistry, University of Southampton, Southampton, UK.
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32
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Prisco NA, Pinon AC, Emsley L, Chmelka BF. Scaling analyses for hyperpolarization transfer across a spin-diffusion barrier and into bulk solid media. Phys Chem Chem Phys 2021; 23:1006-1020. [PMID: 33404028 DOI: 10.1039/d0cp03195j] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
By analogy to heat and mass transfer film theory, a general approach is introduced for determining hyperpolarization transfer rates between dilute electron spins and a surrounding nuclear ensemble. These analyses provide new quantitative relationships for understanding, predicting, and optimizing the effectiveness of hyperpolarization protocols, such as Dynamic Nuclear Polarization (DNP) under magic-angle spinning conditions. An empirical DNP polarization-transfer coefficient is measured as a function of the bulk matrix 1H spin density and indicates the presence of two distinct kinetic regimes associated with different rate-limiting polarization transfer phenomena. Dimensional property relationships are derived and used to evaluate the competitive rates of spin polarization generation, propagation, and dissipation that govern hyperpolarization transfer between large coupled spin ensembles. The quantitative analyses agree closely with experimental measurements for the accumulation, propagation, and dissipation of hyperpolarization in solids and provide evidence for kinetically-limited transfer associated with a spin-diffusion barrier. The results and classical approach yield general design criteria for analyzing and optimizing polarization transfer processes involving complex interfaces and composite media for applications in materials science, physical chemistry and nuclear spintronics.
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Affiliation(s)
- Nathan A Prisco
- Department of Chemical Engineering, University of California Santa Barbara, USA.
| | - Arthur C Pinon
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland
| | - Lyndon Emsley
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland
| | - Bradley F Chmelka
- Department of Chemical Engineering, University of California Santa Barbara, USA.
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33
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Rodin B, Ivanov K. Representation of population exchange at level anti-crossings. MAGNETIC RESONANCE (GOTTINGEN, GERMANY) 2020; 1:347-365. [PMID: 38111911 PMCID: PMC10726024 DOI: 10.5194/mr-1-347-2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 11/18/2020] [Indexed: 12/20/2023]
Abstract
A theoretical framework is proposed to describe the spin dynamics driven by coherent spin mixing at level anti-crossings (LACs). We briefly introduce the LAC concept and propose to describe the spin dynamics using a vector of populations of the diabatic eigenstates. In this description, each LAC gives rise to a pairwise redistribution of eigenstate populations, allowing one to construct the total evolution operator of the spin system. Additionally, we take into account that in the course of spin evolution a "rotation" of the eigenstate basis case take place. The approach is illustrated by a number of examples, dealing with magnetic field inversion, cross-polarization, singlet-state nuclear magnetic resonance and parahydrogen-induced polarization.
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Affiliation(s)
- Bogdan A. Rodin
- International Tomography Center, Siberian Branch of the Russian Academy of Science, Novosibirsk, 630090, Russia
- Physics Department, Novosibirsk State University, Novosibirsk, 630090, Russia
| | - Konstantin L. Ivanov
- International Tomography Center, Siberian Branch of the Russian Academy of Science, Novosibirsk, 630090, Russia
- Physics Department, Novosibirsk State University, Novosibirsk, 630090, Russia
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34
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Li Y, Equbal A, Tabassum T, Han S. 1H Thermal Mixing Dynamic Nuclear Polarization with BDPA as Polarizing Agents. J Phys Chem Lett 2020; 11:9195-9202. [PMID: 33058676 DOI: 10.1021/acs.jpclett.0c01721] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Dynamic Nuclear Polarization (DNP) is a sensitivity enhancing technique for Nuclear Magnetic Resonance. A recent discovery of Overhauser Effect (OE) DNP in insulating systems under cryogenic conditions using 1,3-bisdiphenylene-2-phenylallyl (BDPA) as the polarizing agent (PA) has caught attention due to its promising DNP performance at a high magnetic field and under fast magic angle spinning conditions. However, the mechanism of OE in insulating-solids/BDPA is unclear. We present an alternative explanation that the dominant underlying DNP mechanism of BDPA is Thermal Mixing (TM). This is ascertained with the discovery that TM effect is enhanced by multi-electron spin coupling, which is corroborated by an asymmetric electron paramagnetic resonance line shape signifying the coexistence of clustered and isolated BDPA species, and by hyperpolarized electron spin populations giving rise to an electron spin polarization gradient which are characteristic signatures of TM DNP. Finally, quantum mechanical simulations using spatially asymmetrically coupled three electron spins and a nuclear spin demonstrate that triple-flip DNP, with hyperfine fluctuations turned off, can yield the 1H DNP profile as observed with BDPA. Clarifying the DNP mechanism is critical to develop design principles for optimizing the PA for achieving optimal DNP efficiency.
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Affiliation(s)
- Yuanxin Li
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Asif Equbal
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Tarnuma Tabassum
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Songi Han
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
- Department of Chemical Engineering, University of California, Santa Barbara, Santa Barbara, California 93106, United States
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35
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Tran NT, Mentink-Vigier F, Long JR. Dynamic Nuclear Polarization of Biomembrane Assemblies. Biomolecules 2020; 10:E1246. [PMID: 32867275 PMCID: PMC7565305 DOI: 10.3390/biom10091246] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 08/10/2020] [Accepted: 08/11/2020] [Indexed: 01/02/2023] Open
Abstract
While atomic scale structural and dynamic information are hallmarks of nuclear magnetic resonance (NMR) methodologies, sensitivity is a fundamental limitation in NMR studies. Fully exploiting NMR capabilities to study membrane proteins is further hampered by their dilution within biological membranes. Recent developments in dynamic nuclear polarization (DNP), which can transfer the relatively high polarization of unpaired electrons to nuclear spins, show promise for overcoming the sensitivity bottleneck and enabling NMR characterization of membrane proteins under native-like conditions. Here we discuss fundamental aspects of DNP-enhanced solid-state NMR spectroscopy, experimental details relevant to the study of lipid assemblies and incorporated proteins, and sensitivity gains which can be realized in biomembrane-based samples. We also present unique insights which can be gained from DNP measurements and prospects for further development of the technique for elucidating structures and orientations of membrane proteins in native lipid environments.
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Affiliation(s)
- Nhi T. Tran
- Department of Chemistry, University of Florida, Gainesville, FL 32611, USA;
| | - Frédéric Mentink-Vigier
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, USA;
| | - Joanna R. Long
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, USA;
- Department of Biochemistry & Molecular Biology and McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
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36
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Perras FA, Raju M, Carnahan SL, Akbarian D, van Duin ACT, Rossini AJ, Pruski M. Full-Scale Ab Initio Simulation of Magic-Angle-Spinning Dynamic Nuclear Polarization. J Phys Chem Lett 2020; 11:5655-5660. [PMID: 32453582 DOI: 10.1021/acs.jpclett.0c00955] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Theoretical models aimed at describing magic-angle-spinning (MAS) dynamic nuclear polarization (DNP) NMR have great potential in facilitating the in silico design of DNP polarizing agents and formulations. These models must typically face a trade-off between the accuracy of a strict quantum mechanical description and the need for using realistically large spin systems, for instance, using phenomenological models. Here, we show that the use of aggressive state-space restrictions and an optimization strategy allows full-scale ab initio MAS-DNP simulations of spin systems containing thousands of nuclei. Our simulations are shown to reproduce experimental DNP enhancements quantitatively, including their MAS rate dependence, for both frozen solutions and solid materials. They also reveal the importance of a previously unrecognized structural feature found in some polarizing agents that helps minimize the sensitivity losses imposed by the spin diffusion barrier.
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Affiliation(s)
| | - Muralikrishna Raju
- U.S. DOE, Ames Laboratory, Ames, Iowa 50011, United States
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States
| | - Scott L Carnahan
- U.S. DOE, Ames Laboratory, Ames, Iowa 50011, United States
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States
| | - Dooman Akbarian
- Department of Mechanical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Adri C T van Duin
- Department of Mechanical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Aaron J Rossini
- U.S. DOE, Ames Laboratory, Ames, Iowa 50011, United States
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States
| | - Marek Pruski
- U.S. DOE, Ames Laboratory, Ames, Iowa 50011, United States
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States
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37
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Chakraborty A, Deligey F, Quach J, Mentink-Vigier F, Wang P, Wang T. Biomolecular complex viewed by dynamic nuclear polarization solid-state NMR spectroscopy. Biochem Soc Trans 2020; 48:1089-1099. [PMID: 32379300 PMCID: PMC7565284 DOI: 10.1042/bst20191084] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Revised: 04/17/2020] [Accepted: 04/20/2020] [Indexed: 01/07/2023]
Abstract
Solid-state nuclear magnetic resonance (ssNMR) is an indispensable tool for elucidating the structure and dynamics of insoluble and non-crystalline biomolecules. The recent advances in the sensitivity-enhancing technique magic-angle spinning dynamic nuclear polarization (MAS-DNP) have substantially expanded the territory of ssNMR investigations and enabled the detection of polymer interfaces in a cellular environment. This article highlights the emerging MAS-DNP approaches and their applications to the analysis of biomolecular composites and intact cells to determine the folding pathway and ligand binding of proteins, the structural polymorphism of low-populated biopolymers, as well as the physical interactions between carbohydrates, proteins, and lignin. These structural features provide an atomic-level understanding of many cellular processes, promoting the development of better biomaterials and inhibitors. It is anticipated that the capabilities of MAS-DNP in biomolecular and biomaterial research will be further enlarged by the rapid development of instrumentation and methodology.
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Affiliation(s)
- Arnab Chakraborty
- Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Fabien Deligey
- Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Jenny Quach
- Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803, USA
| | | | - Ping Wang
- Department of Microbiology, Immunology, and Parasitology, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
| | - Tuo Wang
- Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803, USA
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38
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Mandal S, Sigurdsson ST. On the Limited Stability of BDPA Radicals. Chemistry 2020; 26:7486-7491. [PMID: 32396245 DOI: 10.1002/chem.202001084] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Indexed: 11/08/2022]
Abstract
1,3-Bis(diphenylene)-2-phenylallyl (BDPA)-based radicals are of interest as polarizing agents for dynamic nuclear polarization (DNP). For this purpose, a BDPA-nitroxide biradical, employing a phosphodiester linkage, was synthesized. Contrary to what is commonly assumed, BDPA-derived radicals were observed to have limited stability. Hence, the effects of various factors on the stability of BDPA radicals were investigated. Solvent polarity was found to play a significant role on degradation; a polar BDPA radical was observed to degrade faster in a non-polar solvent, whereas non-polar radicals were more unstable in polar solvents. The rate of decomposition was found to increase non-linearly with increasing radical concentration; a 2-fold increase in concentration led to a 3-fold increase in the rate of degradation. Collectively, these results indicate that the dimerization is a significant degradation pathway for BDPA radicals and indeed, a dimer of one BDPA radical was detected by mass spectrometry.
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Affiliation(s)
- Sucharita Mandal
- Department of Chemistry, Science Institute, University of Iceland, Dunhaga 3, 107, Reykjavik, Iceland
| | - Snorri Th Sigurdsson
- Department of Chemistry, Science Institute, University of Iceland, Dunhaga 3, 107, Reykjavik, Iceland
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39
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Lim BJ, Ackermann BE, Debelouchina GT. Targetable Tetrazine-Based Dynamic Nuclear Polarization Agents for Biological Systems. Chembiochem 2020; 21:1315-1319. [PMID: 31746101 PMCID: PMC7445144 DOI: 10.1002/cbic.201900609] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2019] [Indexed: 12/13/2022]
Abstract
Dynamic nuclear polarization (DNP) has shown great promise as a tool to enhance the nuclear magnetic resonance signals of proteins in the cellular environment. As sensitivity increases, the ability to select and efficiently polarize a specific macromolecule over the cellular background has become desirable. Herein, we address this need and present a tetrazine-based DNP agent that can be targeted selectively to proteins containing the unnatural amino acid (UAA) norbornene-lysine. This UAA can be introduced efficiently into the cellular milieu by genetic means. Our approach is bio-orthogonal and easily adaptable to any protein of interest. We illustrate the scope of our methodology and investigate the DNP transfer mechanisms in several biological systems. Our results shed light on the complex polarization-transfer pathways in targeted DNP and ultimately pave the way to selective DNP-enhanced NMR spectroscopy in both bacterial and mammalian cells.
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Affiliation(s)
- Byung Joon Lim
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA
| | - Bryce E. Ackermann
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA
| | - Galia T. Debelouchina
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA
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40
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Lund A, Casano G, Menzildjian G, Kaushik M, Stevanato G, Yulikov M, Jabbour R, Wisser D, Renom-Carrasco M, Thieuleux C, Bernada F, Karoui H, Siri D, Rosay M, Sergeyev IV, Gajan D, Lelli M, Emsley L, Ouari O, Lesage A. TinyPols: a family of water-soluble binitroxides tailored for dynamic nuclear polarization enhanced NMR spectroscopy at 18.8 and 21.1 T. Chem Sci 2020; 11:2810-2818. [PMID: 34084341 PMCID: PMC8157490 DOI: 10.1039/c9sc05384k] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Accepted: 01/31/2020] [Indexed: 11/21/2022] Open
Abstract
Dynamic Nuclear Polarization (DNP) has recently emerged as a key method to increase the sensitivity of solid-state NMR spectroscopy under Magic Angle Spinning (MAS). While efficient binitroxide polarizing agents such as AMUPol have been developed for MAS DNP NMR at magnetic fields up to 9.4 T, their performance drops rapidly at higher fields due to the unfavorable field dependence of the cross-effect (CE) mechanism and AMUPol-like radicals were so far disregarded in the context of the development of polarizing agents for very high-field DNP. Here, we introduce a new family of water-soluble binitroxides, dubbed TinyPols, which have a three-bond non-conjugated flexible amine linker allowing sizable couplings between the two unpaired electrons. We show that this adjustment of the linker is crucial and leads to unexpectedly high DNP enhancement factors at 18.8 T and 21.1 T: an improvement of about a factor 2 compared to AMUPol is reported for spinning frequencies ranging from 5 to 40 kHz, with ε H of up to 90 at 18.8 T and 38 at 21.1 T for the best radical in this series, which are the highest MAS DNP enhancements measured so far in aqueous solutions at these magnetic fields. This work not only breathes a new momentum into the design of binitroxides tailored towards high magnetic fields, but also is expected to push the application frontiers of high-resolution DNP MAS NMR, as demonstrated here on a hybrid mesostructured silica material.
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Affiliation(s)
- Alicia Lund
- Centre de RMN à; Très Hauts Champs, Université; de Lyon (CNRS/ENS Lyon/UCB Lyon 1) 69100 Villeurbanne France
| | | | - Georges Menzildjian
- Centre de RMN à; Très Hauts Champs, Université; de Lyon (CNRS/ENS Lyon/UCB Lyon 1) 69100 Villeurbanne France
| | - Monu Kaushik
- Centre de RMN à; Très Hauts Champs, Université; de Lyon (CNRS/ENS Lyon/UCB Lyon 1) 69100 Villeurbanne France
| | - Gabriele Stevanato
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL) CH-1015 Lausanne Switzerland
| | - Maxim Yulikov
- Department of Chemistry and Applied Biosciences, Eidgenössische Technische Hochschule Zürich CH-8093 Zürich Switzerland
| | - Ribal Jabbour
- Centre de RMN à; Très Hauts Champs, Université; de Lyon (CNRS/ENS Lyon/UCB Lyon 1) 69100 Villeurbanne France
| | - Dorothea Wisser
- Centre de RMN à; Très Hauts Champs, Université; de Lyon (CNRS/ENS Lyon/UCB Lyon 1) 69100 Villeurbanne France
| | - Marc Renom-Carrasco
- Institute of Chemistry of Lyon, Laboratory C2P2 UMR 5265-CNRS-University Lyon 1-CPE Lyon, University of Lyon 43 Bd du 11 Novembre 1918 69616 Villeurbanne France
| | - Chloé Thieuleux
- Institute of Chemistry of Lyon, Laboratory C2P2 UMR 5265-CNRS-University Lyon 1-CPE Lyon, University of Lyon 43 Bd du 11 Novembre 1918 69616 Villeurbanne France
| | | | | | - Didier Siri
- Aix Marseille Univ, CNRS, ICR Marseille France
| | - Melanie Rosay
- Bruker Biospin Corporation 15 Fortune Drive Billerica Massachusetts 01821 USA
| | - Ivan V Sergeyev
- Bruker Biospin Corporation 15 Fortune Drive Billerica Massachusetts 01821 USA
| | - David Gajan
- Centre de RMN à; Très Hauts Champs, Université; de Lyon (CNRS/ENS Lyon/UCB Lyon 1) 69100 Villeurbanne France
| | - Moreno Lelli
- Center of Magnetic Resonance (CERM), University of Florence Via Luigi Sacconi 6 50019 Sesto Fiorentino Italy
| | - Lyndon Emsley
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL) CH-1015 Lausanne Switzerland
| | | | - Anne Lesage
- Centre de RMN à; Très Hauts Champs, Université; de Lyon (CNRS/ENS Lyon/UCB Lyon 1) 69100 Villeurbanne France
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41
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Mentink-Vigier F. Optimizing nitroxide biradicals for cross-effect MAS-DNP: the role of g-tensors' distance. Phys Chem Chem Phys 2020; 22:3643-3652. [PMID: 31998899 DOI: 10.1039/c9cp06201g] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Nitroxide biradicals are common polarizing agents used to enhance the sensitivity of solid-state NMR experiments via Magic Angle Spinning Dynamic Nuclear Polarization (MAS-DNP). These biradicals are used to increase the polarization of protons through the cross-effect mechanism, which requires two unpaired electrons with a Larmor frequency difference greater than that of the protons. From their early conception, the relative orientation of the nitroxide rings has been identified as a critical factor determining their MAS-DNP performance. However, the MAS leads to a complex DNP mechanism with time dependent energy level anti-crossings making it difficult to pinpoint the role of relative g-tensor orientation. In this article, a single parameter called "g-tensors' distance" is introduced to characterize the relative orientation's impact on the MAS-DNP field profiles. It is demonstrated for the first time how the g-tensors' distance determines the nuclear hyperpolarization and depolarization properties of a given biradical. This provides a new critical parameter that paves the way for more efficient bis-nitroxides for MAS-DNP.
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Affiliation(s)
- Frédéric Mentink-Vigier
- National High Magnetic Field Laboratory, Florida State University, 1800 E. Paul Dirac Dr, Tallahassee, FL 32310, USA.
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42
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Equbal A, Tagami K, Han S. Balancing dipolar and exchange coupling in biradicals to maximize cross effect dynamic nuclear polarization. Phys Chem Chem Phys 2020; 22:13569-13579. [DOI: 10.1039/d0cp02051f] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Balancing dipolar and exchange coupling is essential for efficient Cross Effect DNP. This explains the complex performance of standard radicals (AMUPOL and HyTek) at high magnetic field and fast spinning.
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Affiliation(s)
- Asif Equbal
- Department of Chemistry and Biochemistry
- University of California
- Santa Barbara
- USA
| | - Kan Tagami
- Department of Chemistry and Biochemistry
- University of California
- Santa Barbara
- USA
| | - Songi Han
- Department of Chemistry and Biochemistry
- University of California
- Santa Barbara
- USA
- Department of Chemical Engineering
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43
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Mandal S, Sigurdsson ST. Water-soluble BDPA radicals with improved persistence. Chem Commun (Camb) 2020; 56:13121-13124. [DOI: 10.1039/d0cc04920d] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
1,3-Bis(diphenylene)-2-phenylallyl (BDPA) radicals are promising polarizing agents for dynamic nuclear polarization (DNP) NMR spectroscopy. BDPAs containing tetraalkyl/aryl-ammonium groups have increased persistence and solubility in polar solvents.
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Affiliation(s)
- Sucharita Mandal
- University of Iceland
- Department of Chemistry
- Science Institute
- Reykjavik 107
- Iceland
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44
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Grätz S, de Olivera Junior M, Gutmann T, Borchardt L. A comprehensive approach for the characterization of porous polymers using 13C and 15N dynamic nuclear polarization NMR spectroscopy. Phys Chem Chem Phys 2020; 22:23307-23314. [DOI: 10.1039/d0cp04010j] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
DNP enhanced solid-state NMR techniques are presented as powerful tools to characterize amorphous porous polymers that are of insoluble nature.
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Affiliation(s)
- Sven Grätz
- Inorganic Chemistry I
- Ruhr-Universität Bochum Universitätsstrasse 150
- 44780 Bochum
- Germany
| | - Marcos de Olivera Junior
- Technical University Darmstadt
- Institute for Inorganic and Physical Chemistry
- Alarich-Weiss Straße 4
- 64287 Darmstadt
- Germany
| | - Torsten Gutmann
- Technical University Darmstadt
- Institute for Inorganic and Physical Chemistry
- Alarich-Weiss Straße 4
- 64287 Darmstadt
- Germany
| | - Lars Borchardt
- Inorganic Chemistry I
- Ruhr-Universität Bochum Universitätsstrasse 150
- 44780 Bochum
- Germany
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45
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Equbal A, Tagami K, Han S. Pulse-Shaped Dynamic Nuclear Polarization under Magic-Angle Spinning. J Phys Chem Lett 2019; 10:7781-7788. [PMID: 31790265 DOI: 10.1021/acs.jpclett.9b03070] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Dynamic nuclear polarization (DNP) under magic-angle spinning (MAS) is transforming the scope of solid-state NMR by enormous signal amplification through transfer of polarization from electron spins to nuclear spins. Contemporary MAS-DNP exclusively relies on monochromatic continuous-wave (CW) irradiation of the electron spin resonance. This limits control on electron spin dynamics, which renders the DNP process inefficient, especially at higher magnetic fields and non cryogenic temperatures. Pulse-shaped microwave irradiation of the electron spins is predicted to overcome these challenges but hitherto has never been implemented under MAS. Here, we debut pulse-shaped microwave irradiation using arbitrary-waveform generation (AWG) which allows controlled recruitment of a greater number of electron spins per unit time, favorable for MAS-DNP. Experiments and quantum mechanical simulations demonstrate that pulse-shaped DNP is superior to CW-DNP for mixed radical system, especially when the electron spin resonance is heterogeneously broadened and/or when its spin-lattice relaxation is fast compared to the MAS rotor period, opening new prospects for MAS-DNP.
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Affiliation(s)
- Asif Equbal
- Department of Chemistry and Biochemistry , University of California , Santa Barbara , California 93106 , United States
| | - Kan Tagami
- Department of Chemistry and Biochemistry , University of California , Santa Barbara , California 93106 , United States
| | - Songi Han
- Department of Chemistry and Biochemistry , University of California , Santa Barbara , California 93106 , United States
- Department of Chemical Engineering , University of California , Santa Barbara , California 93106 , United States
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46
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Reese M, George C, Yang C, Jawla S, Grün JT, Schwalbe H, Redfield C, Temkin RJ, Griffin RG. Modular, triple-resonance, transmission line DNP MAS probe for 500 MHz/330 GHz. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 307:106573. [PMID: 31505305 PMCID: PMC6766420 DOI: 10.1016/j.jmr.2019.106573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 08/12/2019] [Accepted: 08/13/2019] [Indexed: 06/10/2023]
Abstract
We describe the design and construction of a modular, triple-resonance, fully balanced, DNP-MAS probe based on transmission line technology and its integration into a 500 MHz/330 GHz DNP-NMR spectrometer. A novel quantitative probe design and characterization strategy is developed and employed to achieve optimal sensitivity, RF homogeneity and excellent isolation between channels. The resulting three channel HCN probe has a modular design with each individual, swappable module being equipped with connectorized, transmission line ports. This strategy permits attachment of a mating connector that facilitates accurate impedance measurements at these ports and allows characterization and adjustment (e.g. for balancing or tuning/matching) of each component individually. The RF performance of the probe is excellent; for example, the 13C channel attains a Rabi frequency of 280 kHz for a 3.2 mm rotor. In addition, a frequency tunable 330 GHz gyrotron operating at the second harmonic of the electron cyclotron frequency was developed for DNP applications. Careful alignment of the corrugated waveguide led to minimal loss of the microwave power, and an enhancement factor ε = 180 was achieved for U-13C urea in the glassy matrix at 80 K. We demonstrated the operation of the system with acquisition of multidimensional spectra of cross-linked lysozyme crystals which are insoluble in glycerol-water mixtures used for DNP and samples of RNA.
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Affiliation(s)
- Marcel Reese
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, United States
| | - Christy George
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, United States
| | - Chen Yang
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, United States
| | - Sudheer Jawla
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA 02139, United States
| | - J Tassilo Grün
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance, Johann Wolfgang Goethe-Universität Frankfurt, 60438 Frankfurt, Germany
| | - Harald Schwalbe
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance, Johann Wolfgang Goethe-Universität Frankfurt, 60438 Frankfurt, Germany
| | - Christina Redfield
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom
| | - Richard J Temkin
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA 02139, United States; Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, United States
| | - Robert G Griffin
- Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, United States.
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47
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Rankin AGM, Trébosc J, Pourpoint F, Amoureux JP, Lafon O. Recent developments in MAS DNP-NMR of materials. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2019; 101:116-143. [PMID: 31189121 DOI: 10.1016/j.ssnmr.2019.05.009] [Citation(s) in RCA: 78] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 05/21/2019] [Accepted: 05/21/2019] [Indexed: 05/03/2023]
Abstract
Solid-state NMR spectroscopy is a powerful technique for the characterization of the atomic-level structure and dynamics of materials. Nevertheless, the use of this technique is often limited by its lack of sensitivity, which can prevent the observation of surfaces, defects or insensitive isotopes. Dynamic Nuclear Polarization (DNP) has been shown to improve by one to three orders of magnitude the sensitivity of NMR experiments on materials under Magic-Angle Spinning (MAS), at static magnetic field B0 ≥ 5 T, conditions allowing for the acquisition of high-resolution spectra. The field of DNP-NMR spectroscopy of materials has undergone a rapid development in the last ten years, spurred notably by the availability of commercial DNP-NMR systems. We provide here an in-depth overview of MAS DNP-NMR studies of materials at high B0 field. After a historical perspective of DNP of materials, we describe the DNP transfers under MAS, the transport of polarization by spin diffusion and the various contributions to the overall sensitivity of DNP-NMR experiments. We discuss the design of tailored polarizing agents and the sample preparation in the case of materials. We present the DNP-NMR hardware and the influence of key experimental parameters, such as microwave power, magnetic field, temperature and MAS frequency. We give an overview of the isotopes that have been detected by this technique, and the NMR methods that have been combined with DNP. Finally, we show how MAS DNP-NMR has been applied to gain new insights into the structure of organic, hybrid and inorganic materials with applications in fields, such as health, energy, catalysis, optoelectronics etc.
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Affiliation(s)
- Andrew G M Rankin
- Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181, UCCS, Unité de Catalyse et Chimie du Solide, F-59000, Lille, France
| | - Julien Trébosc
- Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181, UCCS, Unité de Catalyse et Chimie du Solide, F-59000, Lille, France; Univ. Lille, CNRS-FR2638, Fédération Chevreul, F-59000 Lille, France
| | - Frédérique Pourpoint
- Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181, UCCS, Unité de Catalyse et Chimie du Solide, F-59000, Lille, France
| | - Jean-Paul Amoureux
- Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181, UCCS, Unité de Catalyse et Chimie du Solide, F-59000, Lille, France; Bruker Biospin, 34 rue de l'industrie, F-67166, Wissembourg, France
| | - Olivier Lafon
- Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181, UCCS, Unité de Catalyse et Chimie du Solide, F-59000, Lille, France; Institut Universitaire de France, 1 rue Descartes, F-75231, Paris, France.
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48
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Tagami K, Equbal A, Kaminker I, Kirtman B, Han S. Biradical rotamer states tune electron J coupling and MAS dynamic nuclear polarization enhancement. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2019; 101:12-20. [PMID: 31075525 DOI: 10.1016/j.ssnmr.2019.04.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Revised: 03/30/2019] [Accepted: 04/09/2019] [Indexed: 05/13/2023]
Abstract
Cross Effect (CE) Dynamic Nuclear Polarization (DNP) relies on the dipolar (D) and exchange (J) coupling interaction between two electron spins. Until recently only the electron spin D coupling was explicitly included in quantifying the DNP mechanism. Recent literature discusses the potential role of J coupling in DNP, but does not provide an account of the distribution and source of electron spin J coupling of commonly used biradicals in DNP. In this study, we quantified the distribution of electron spin J coupling in AMUPol and TOTAPol biradicals using a combination of continuous wave (CW) X-band electron paramagnetic resonance (EPR) lineshape analysis in a series of solvents and at variable temperatures in solution - a state to be vitrified for DNP. We found that both radicals show a temperature dependent distribution of J couplings, and the source of this distribution to be conformational dynamics. To qualify this conformational dependence of J coupling in both molecules we carry out Broken Symmetry DFT calculations which show that the biradical rotamer distribution can account for a large distribution of J couplings, with the magnitude of J coupling directly depending on the relative orientation of the electron spin pair. We demonstrate that the electron spin J couplings in both AMUPol and TOTAPol span a much wider distribution than suggested in the literature. We affirm the importance of electron spin J coupling for DNP with density matrix simulations of DNP in Liouville space and under magic angle spinning, showcasing that a rotamer with high J coupling and optimum relative g-tensor orientation can significantly boost the DNP performance compared to random orientations of the electron spin pair. We conclude that moderate electron spin J coupling above a threshold value can facilitate DNP enhancements.
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Affiliation(s)
- Kan Tagami
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, 93106, United States
| | - Asif Equbal
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, 93106, United States
| | - Ilia Kaminker
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, 93106, United States
| | - Bernard Kirtman
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, 93106, United States
| | - Songi Han
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, 93106, United States; Department of Chemical Engineering, University of California, Santa Barbara, CA, 93106, United States.
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49
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Wang X, Caulkins BG, Riviere G, Mueller LJ, Mentink-Vigier F, Long JR. Direct dynamic nuclear polarization of 15N and 13C spins at 14.1 T using a trityl radical and magic angle spinning. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2019; 100:85-91. [PMID: 31026722 PMCID: PMC6604067 DOI: 10.1016/j.ssnmr.2019.03.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 03/27/2019] [Accepted: 03/28/2019] [Indexed: 05/05/2023]
Abstract
We investigate solid-state dynamic nuclear polarization of 13C and 15N nuclei using monoradical trityl OX063 as a polarizing agent in a magnetic field of 14.1 T with magic angle spinning at ∼100 K. We monitored the field dependence of direct 13C and 15N polarization for frozen [13C, 15N] urea and achieved maximum absolute enhancement factors of 240 and 470, respectively. The field profiles are consistent with polarization of 15N spins via either the solid effect or the cross effect, and polarization of 13C spins via a combination of cross effect and solid effect. For microcrystalline, 15N-enriched tryptophan synthase sample containing trityl radical, a 1500-fold increase in 15N signal was observed under microwave irradiation. These results show the promise of trityl radicals and their derivatives for direct polarization of low gamma, spin-½ nuclei at high magnetic fields and suggest a novel approach for selectively polarizing specific moieties or for polarizing systems which have low levels of protonation.
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Affiliation(s)
- Xiaoling Wang
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, 32310, USA
| | - Bethany G Caulkins
- Department of Chemistry, University of California Riverside, Riverside, CA, 92521, USA
| | - Gwladys Riviere
- Department of Biochemistry and Molecular Biology, McKnight Brain Institute and National High Magnetic Field Laboratory, University of Florida, Gainesville, FL, 32610-0245, USA
| | - Leonard J Mueller
- Department of Chemistry, University of California Riverside, Riverside, CA, 92521, USA
| | - Frederic Mentink-Vigier
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, 32310, USA
| | - Joanna R Long
- Department of Biochemistry and Molecular Biology, McKnight Brain Institute and National High Magnetic Field Laboratory, University of Florida, Gainesville, FL, 32610-0245, USA.
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Sugishita T, Matsuki Y, Fujiwara T. Absolute 1H polarization measurement with a spin-correlated component of magnetization by hyperpolarized MAS-DNP solid-state NMR. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2019; 99:20-26. [PMID: 30849736 DOI: 10.1016/j.ssnmr.2019.02.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Revised: 02/14/2019] [Accepted: 02/14/2019] [Indexed: 06/09/2023]
Abstract
Sensitivity of magic-angle spinning (MAS) NMR spectroscopy has been dramatically improved by the advent of high-field dynamic nuclear polarization (DNP) technique and its rapid advances over the past decades. In this course, discussions on ways to improve the DNP enhancement factor or the overall sensitivity gain have been numerous, and led to a number of methodological and instrumental breakthroughs. Beyond the sensitivity gain, however, discussions on accurate quantification of the 1H polarization amplitude achievable in a sample with DNP have been relatively rare. Here, we propose a new method for quantifying the local 1H hyperpolarization amplitude, which is applicable to un-oriented/powdered solid samples under MAS NMR conditions. The method is based on the ability to observe the high-order spin-correlated term (2IzSz) intrinsic to a hyperpolarized IS two-spin state, separately from the lowest-order Zeeman term (Sz) in quasi-equilibrium magnetization. The quantification procedure does not require evaluation of signal amplitudes for a "microwave-off" condition and for an un-doped reference sample, and thus enables quick and accurate quantification unaffected by the effects of the paramagnetic quenching and the MAS-induced depolarization. The method is also shown to elucidate spatial polarization distribution through the 2IzSz term prepared domain-selectively. As a potential application, we also demonstrate 2D DQ-SQ spectroscopy utilizing the 2IzSz term that is generated in a spatially selective manner without using IS dipolar or J coupling. These salient features may be evolved into a way for characterizing mesoscopic molecular assemblies of medical/biological importance.
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Affiliation(s)
| | - Yoh Matsuki
- Institute for Protein Research, Osaka University, Japan; Quantum Information and Quantum Biology Division, Institute for Open and Transdisciplinary Research Initiatives, Osaka University, Japan
| | - Toshimichi Fujiwara
- Institute for Protein Research, Osaka University, Japan; Quantum Information and Quantum Biology Division, Institute for Open and Transdisciplinary Research Initiatives, Osaka University, Japan.
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