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Mudgil M, Kurur ND. Excitation of long-lived nuclear spin order using spin-locking: a geometrical formalism. Phys Chem Chem Phys 2024. [PMID: 38990198 DOI: 10.1039/d4cp01995d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/12/2024]
Abstract
Over the last two decades, numerous pulse sequences have been introduced for the excitation of long-lived spin order (LLS) in high fields. The long continuous wave (CW) or adiabatic pulses used in the SLIC and APSOC sequences should remind one of the spin-locking pulses that are used to induce cross-polarization (CP). Dynamics during these spin-lockings in CP experiments are explained through a geometrical formalism. However, the SLIC and APSOC sequences are described in terms of the energy-level picture or in the language of level anti-crossings. Motivated by this analogy, this work presents here a geometrical formalism for the LLS excitation by spin-locking pulses in weakly coupled systems. The formalism is similar to the one used for CP dynamics and reveals new pulse sequences involving CW or adiabatic locking. A similar formalism for the sustaining period of LLS is also provided, which reveals new features of the dynamics and suggests the usage of modulated spin-lockings for proper LLS sustaining. For strong and intermediate regimes, although a simple geometrical formalism seems infeasible, a new pulse sequence that employs a ramp-down adiabatic pulse for both LLS excitation and reconversion to observables in both these regimes is presented here. Given the similarities between LLS excitation and well-developed CP, it may be anticipated that this work would initiate the search for new LLS excitation methods and applications.
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Affiliation(s)
- Manjeet Mudgil
- Chemistry Department, Indian Institute of Technology Delhi, New Delhi 110016, India.
| | - Narayanan D Kurur
- Chemistry Department, Indian Institute of Technology Delhi, New Delhi 110016, India.
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Korzeczek MC, Dagys L, Müller C, Tratzmiller B, Salhov A, Eichhorn T, Scheuer J, Knecht S, Plenio MB, Schwartz I. Towards a unified picture of polarization transfer - pulsed DNP and chemically equivalent PHIP. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2024; 362:107671. [PMID: 38614057 DOI: 10.1016/j.jmr.2024.107671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 03/30/2024] [Accepted: 04/03/2024] [Indexed: 04/15/2024]
Abstract
Nuclear spin hyperpolarization techniques, such as dynamic nuclear polarization (DNP) and parahydrogen-induced polarization (PHIP), have revolutionized nuclear magnetic resonance and magnetic resonance imaging. In these methods, a readily available source of high spin order, either electron spins in DNP or singlet states in hydrogen for PHIP, is brought into close proximity with nuclear spin targets, enabling efficient transfer of spin order under external quantum control. Despite vast disparities in energy scales and interaction mechanisms between electron spins in DNP and nuclear singlet states in PHIP, a pseudo-spin formalism allows us to establish an intriguing equivalence. As a result, the important low-field polarization transfer regime of PHIP can be mapped onto an analogous system equivalent to pulsed-DNP. This establishes a correspondence between key polarization transfer sequences in PHIP and DNP, facilitating the transfer of sequence development concepts. This promises fresh insights and significant cross-pollination between DNP and PHIP polarization sequence developers.
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Affiliation(s)
- Martin C Korzeczek
- Institute of Theoretical Physics and IQST, Albert-Einstein Allee 11, Ulm University, 89081, Ulm, Germany
| | | | | | - Benedikt Tratzmiller
- Institute of Theoretical Physics and IQST, Albert-Einstein Allee 11, Ulm University, 89081, Ulm, Germany; Carl Zeiss MultiSEM GmbH, 73447, Oberkochen, Germany
| | - Alon Salhov
- NVision Imaging Technologies GmbH, 89081, Ulm, Germany; Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem, 91904, Givat Ram, Israel
| | - Tim Eichhorn
- NVision Imaging Technologies GmbH, 89081, Ulm, Germany
| | | | | | - Martin B Plenio
- Institute of Theoretical Physics and IQST, Albert-Einstein Allee 11, Ulm University, 89081, Ulm, Germany.
| | - Ilai Schwartz
- NVision Imaging Technologies GmbH, 89081, Ulm, Germany.
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3
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Abstract
Nuclear magnetization storage, once limited by longitudinal and transverse relaxation lifetimes, T1 and T2, can be prolonged by symmetry-adapted nuclear spin order, i.e. long-lived states (LLS) and long-lived coherences (LLC), which have significantly extended relaxation time constants compared to T1 and T2, respectively. Excitation and/or detection of LLS currently involves pulses covering wide frequency ranges in high-magnetic-field spectrometers. This leads to excitation of unwanted signals that may overlap and interfere with the resonances of interest. Herein, we present a new pulse sequence that converts longitudinal magnetization to LLS and further to detectable magnetization using only frequency-selective pulses. We demonstrate the suitability of this sequence for different J-coupled spin pairs in dipeptide AlaGly and protein Ubiquitin. The newly developed method is adapted for investigations of LLS in complex systems such as proteins and mixtures of metabolites where selected molecular groups are to be investigated separately.
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Affiliation(s)
- Florin Teleanu
- Extreme Light Infrastructure-Nuclear Physics ELI-NP, Laser Gamma Experiments Department (LGED), "Horia Hulubei" National Institute for Physics and Nuclear Engineering IFIN-HH, 30 Reactorului Street, 077125 Bucharest-Măgurele, Romania
- Interdisciplinary School of Doctoral Studies, University of Bucharest, Regina Elisabeta Boulevard, 050663 Bucharest, Romania
| | - Adonis Lupulescu
- Extreme Light Infrastructure-Nuclear Physics ELI-NP, Laser Gamma Experiments Department (LGED), "Horia Hulubei" National Institute for Physics and Nuclear Engineering IFIN-HH, 30 Reactorului Street, 077125 Bucharest-Măgurele, Romania
| | - Paul R Vasos
- Extreme Light Infrastructure-Nuclear Physics ELI-NP, Laser Gamma Experiments Department (LGED), "Horia Hulubei" National Institute for Physics and Nuclear Engineering IFIN-HH, 30 Reactorului Street, 077125 Bucharest-Măgurele, Romania
- Interdisciplinary School of Doctoral Studies, University of Bucharest, Regina Elisabeta Boulevard, 050663 Bucharest, Romania
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Glöggler S, Yang S, Saul P, Mamone S, Kaltschnee L. Bimodal fluorescence/magnetic resonance molecular probes with extended spin lifetimes. Chemistry 2021; 28:e202104158. [PMID: 34854145 PMCID: PMC9302690 DOI: 10.1002/chem.202104158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Indexed: 11/12/2022]
Abstract
Bimodal molecular probes combining nuclear magnetic resonance (NMR) and fluorescence have been widely studied in basic science, as well as clinical research. The investigation of spin phenomena holds promise to broaden the scope of available probes allowing deeper insights into physiological processes. Herein, a class of molecules with a bimodal character with respect to fluorescence and nuclear spin singlet states is introduced. Singlet states are NMR silent but can be probed indirectly. Symmetric, perdeuterated molecules, in which the singlet states can be populated by vanishingly small electron‐mediated couplings (below 1 Hz) are reported. The lifetimes of these states are an order of magnitude longer than the longitudinal relaxation times and up to four minutes at 7 T. Moreover, these molecules show either aggregation induced emission (AIE) or aggregation caused quenching (ACQ) with respect to their fluorescence. In the latter case, the existence of excited dimers, which are proposed to use in a switchable manner in combination with the quenching of nuclear spin singlet states, is observed
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Affiliation(s)
- Stefan Glöggler
- Max-Planck-Institute for Biophysical Chemistry, NMR Signal Enhancement Group, Am Fassberg 11, 37077, Göttingen, GERMANY
| | - Shengjun Yang
- Max-Planck-Institute for Biophysical Chemistry: Max-Planck-Institut fur biophysikalische Chemie, NMR Signal Enhancement, GERMANY
| | - Philip Saul
- Max-Planck-Institute for Biophysical Chemistry: Max-Planck-Institut fur biophysikalische Chemie, NMR Singal Enhancement, GERMANY
| | - Salvatore Mamone
- Max-Planck-Institute for Biophysical Chemistry: Max-Planck-Institut fur biophysikalische Chemie, NMR Signal Enhancement, GERMANY
| | - Lukas Kaltschnee
- Max-Planck-Institute for Biophysical Chemistry: Max-Planck-Institut fur biophysikalische Chemie, NMR Signal Enhancement, GERMANY
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Bengs C, Dagys L, Levitt MH. Robust transformation of singlet order into heteronuclear magnetisation over an extended coupling range. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2020; 321:106850. [PMID: 33190080 DOI: 10.1016/j.jmr.2020.106850] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 10/06/2020] [Accepted: 10/09/2020] [Indexed: 06/11/2023]
Abstract
Several important NMR procedures involve the conversion of nuclear singlet order into heteronuclear magnetisation, including some experiments involving long-lived spin states and parahydrogen-induced hyperpolarisation. However most existing sequences suffer from a limited range of validity or a lack of robustness against experimental imperfections. We present a new radio-frequency scheme for the transformation of the singlet order of a chemically-equivalent homonuclear spin pair into the magnetisation of a heteronuclear coupling partner. The proposed radio-frequency (RF) scheme is called gS2hM (generalized singlet-to-heteronuclear magnetisation) and has good compensation for common experimental errors such as RF and static field inhomogeneities. The sequence retains its robustness for homonuclear spin pairs in the intermediate coupling regime, characterised by the in-pair coupling being of the same order of magnitude as the difference between the out-of-pair couplings. This is a substantial improvement to the validity range of existing sequences. Analytical solutions for the pulse sequence parameters are provided. Experimental results are shown for two test cases.
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Affiliation(s)
- Christian Bengs
- School of Chemistry, Southampton University, University Road, SO17 1BJ, UK.
| | - Laurynas Dagys
- School of Chemistry, Southampton University, University Road, SO17 1BJ, UK.
| | - Malcolm H Levitt
- School of Chemistry, Southampton University, University Road, SO17 1BJ, UK.
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Pravdivtsev AN, Sönnichsen FD, Hövener JB. In vitro singlet state and zero-quantum encoded magnetic resonance spectroscopy: Illustration with N-acetyl-aspartate. PLoS One 2020; 15:e0239982. [PMID: 33002045 PMCID: PMC7529218 DOI: 10.1371/journal.pone.0239982] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 09/16/2020] [Indexed: 12/20/2022] Open
Abstract
Magnetic resonance spectroscopy (MRS) allows the analysis of biochemical processes non-invasively and in vivo. Still, its application in clinical diagnostics is rare. Routine MRS is limited to spatial, chemical and temporal resolutions of cubic centimetres, mM and minutes. In fact, the signal of many metabolites is strong enough for detection, but the resonances significantly overlap, exacerbating identification and quantification. Besides, the signals of water and lipids are much stronger and dominate the entire spectrum. To suppress the background and isolate selected signals, usually, relaxation times, J-coupling and chemical shifts are used. Here, we propose methods to isolate the signals of selected molecular groups within endogenous metabolites by using long-lived spin states (LLS). We exemplify the method by preparing the LLSs of coupled protons in the endogenous molecules N-acetyl-L-aspartic acid (NAA). First, we store polarization in long-lived, double spin states, followed by saturation pulses before the spin order is converted back to observable magnetization or double quantum filters to suppress background signals. We show that LLS and zero-quantum coherences can be used to selectively prepare and measure the signals of chosen metabolites or drugs in the presence of water, inhomogeneous field and highly concentrated fatty solutions. The strong suppression of unwanted signals achieved allowed us to measure pH as a function of chemical shift difference.
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Affiliation(s)
- Andrey N Pravdivtsev
- Section Biomedical Imaging, Molecular Imaging North Competence Center (MOIN CC), Department of Radiology and Neuroradiology, University Medical Center Kiel, Kiel University, Kiel, Germany
| | - Frank D Sönnichsen
- Otto Diels Institute for Organic Chemistry, Kiel University, Kiel, Germany
| | - Jan-Bernd Hövener
- Section Biomedical Imaging, Molecular Imaging North Competence Center (MOIN CC), Department of Radiology and Neuroradiology, University Medical Center Kiel, Kiel University, Kiel, Germany
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Bengs C, Sabba M, Jerschow A, Levitt MH. Generalised magnetisation-to-singlet-order transfer in nuclear magnetic resonance. Phys Chem Chem Phys 2020; 22:9703-9712. [PMID: 32329499 DOI: 10.1039/d0cp00935k] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A variety of pulse sequences have been described for converting nuclear spin magnetisation into long-lived singlet order for nuclear spin-1/2 pairs. Existing sequences operate well in two extreme parameter regimes. The magnetisation-to-singlet (M2S) pulse sequence performs a robust conversion of nuclear spin magnetisation into singlet order in the near-equivalent limit, meaning that the difference in chemical shift frequencies of the two spins is much smaller than the spin-spin coupling. Other pulse sequences operate in the strong-inequivalence regime, where the shift difference is much larger than the spin-spin coupling. However both sets of pulse sequences fail in the intermediate regime, where the chemical shift difference and the spin-spin coupling are roughly equal in magnitude. We describe a generalised version of M2S, called gM2S, which achieves robust singlet order excitation for spin systems ranging from the near-equivalence limit well into the intermediate regime. This closes an important gap left by existing pulse sequences. The efficiency of the gM2S sequence is demonstrated numerically and experimentally for near-equivalent and intermediate-regime cases.
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Affiliation(s)
- Christian Bengs
- School of Chemistry, University of Southampton, University Road, SO17 1BJ, UK.
| | - Mohamed Sabba
- School of Chemistry, University of Southampton, University Road, SO17 1BJ, UK.
| | - Alexej Jerschow
- Department of Chemistry, New York University, New York, NY 10003, USA.
| | - Malcolm H Levitt
- School of Chemistry, University of Southampton, University Road, SO17 1BJ, UK.
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Mamone S, Rezaei-Ghaleh N, Opazo F, Griesinger C, Glöggler S. Singlet-filtered NMR spectroscopy. SCIENCE ADVANCES 2020; 6:eaaz1955. [PMID: 32128422 PMCID: PMC7034991 DOI: 10.1126/sciadv.aaz1955] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Accepted: 12/04/2019] [Indexed: 06/10/2023]
Abstract
Selectively studying parts of proteins and metabolites in tissue with nuclear magnetic resonance promises new insights into molecular structures or diagnostic approaches. Nuclear spin singlet states allow the selection of signals from chemical moieties of interest in proteins or metabolites while suppressing background signal. This selection process is based on the electron-mediated coupling between two nuclear spins and their difference in resonance frequency. We introduce a generalized and versatile pulsed NMR experiment that allows populating singlet states on a broad scale of coupling patterns. This approach allowed us to filter signals from proton pairs in the Alzheimer's disease-related b-amyloid 40 peptide and in metabolites in brain matter. In particular, for glutamine/glutamate, we have discovered a long-lived state in tissue without the typically required singlet sustaining by radiofrequency irradiation. We believe that these findings will open up new opportunities to study metabolites with a view on future in vivo applications.
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Affiliation(s)
- Salvatore Mamone
- NMR Signal Enhancement Group, Max Planck Institute for Biophysical Chemistry, AmFaßberg 11, 37077 Göttingen, Germany
- Center for Biostructural Imaging of Neurodegeneration of UMG, Von-Siebold-Straße 3A, 37075 Göttingen, Germany
| | - Nasrollah Rezaei-Ghaleh
- Department of Neurology, University Medical Center Göttingen, Waldweg 33, 37073 Göttingen, Germany
- Department for NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Faßberg 11, 37077 Göttingen, Germany
| | - Felipe Opazo
- Center for Biostructural Imaging of Neurodegeneration of UMG, Von-Siebold-Straße 3A, 37075 Göttingen, Germany
- Institute for Neuro- and Sensory Physiology, University Medical Center Göttingen, Humboldtallee 23, 37073 Göttingen, Germany
| | - Christian Griesinger
- Department for NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Faßberg 11, 37077 Göttingen, Germany
| | - Stefan Glöggler
- NMR Signal Enhancement Group, Max Planck Institute for Biophysical Chemistry, AmFaßberg 11, 37077 Göttingen, Germany
- Center for Biostructural Imaging of Neurodegeneration of UMG, Von-Siebold-Straße 3A, 37075 Göttingen, Germany
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Erriah B, Elliott SJ. Experimental evidence for the role of paramagnetic oxygen concentration on the decay of long-lived nuclear spin order. RSC Adv 2019; 9:23418-23424. [PMID: 35514498 PMCID: PMC9067289 DOI: 10.1039/c9ra03748a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2019] [Accepted: 07/09/2019] [Indexed: 11/21/2022] Open
Abstract
The sensitivity of longitudinal magnetization and singlet order to relaxation from dissolved paramagnetic oxygen sources in solution is investigated experimentally.
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Affiliation(s)
- Bryan Erriah
- School of Chemistry
- University of Southampton
- Southampton SO17 1BJ
- UK
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