1
|
Parish C, Niedbalski P, Wang Q, Khashami F, Hayati Z, Liu M, Song L, Lumata L. Effects of glassing matrix deuteration on the relaxation properties of hyperpolarized 13C spins and free radical electrons at cryogenic temperatures. J Chem Phys 2019; 150:234307. [PMID: 31228902 PMCID: PMC6588520 DOI: 10.1063/1.5096036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Revised: 05/20/2019] [Accepted: 06/03/2019] [Indexed: 11/14/2022] Open
Abstract
Glassing matrix deuteration could be a beneficial sample preparation method for 13C dynamic nuclear polarization (DNP) when large electron paramagnetic resonance (EPR) width free radicals are used. However, it could yield the opposite DNP effect when samples are doped with small EPR width free radicals. Herein, we have investigated the influence of solvent deuteration on the 13C nuclear and electron relaxation that go along with the effects on 13C DNP intensities at 3.35 T and 1.2 K. For 13C DNP samples doped with trityl OX063, the 13C DNP signals decreased significantly when the protons are replaced by deuterons in glycerol:water or DMSO:water solvents. Meanwhile, the corresponding solid-state 13C T1 relaxation times of trityl OX063-doped samples generally increased upon solvent deuteration. On the other hand, 13C DNP signals improved by a factor of ∼1.5 to 2 upon solvent deuteration of samples doped with 4-oxo-TEMPO. Despite this 13C DNP increase, there were no significant differences recorded in 13C T1 values of TEMPO-doped samples with nondeuterated or fully deuterated glassing matrices. While solvent deuteration appears to have a negligible effect on the electron T1 relaxation of both free radicals, the electron T2 relaxation times of these two free radicals generally increased upon solvent deuteration. These overall results suggest that while the solid-phase 13C DNP signals are dependent upon the changes in total nuclear Zeeman heat capacity, the 13C relaxation effects are related to 2H/1H nuclear spin diffusion-assisted 13C polarization leakage in addition to the dominant paramagnetic relaxation contribution of free radical centers.
Collapse
Affiliation(s)
- Christopher Parish
- Department of Physics, University of Texas at Dallas, 800 West Campbell Road, Richardson, Texas 75080, USA
| | | | - Qing Wang
- Department of Physics, University of Texas at Dallas, 800 West Campbell Road, Richardson, Texas 75080, USA
| | - Fatemeh Khashami
- Department of Physics, University of Texas at Dallas, 800 West Campbell Road, Richardson, Texas 75080, USA
| | | | | | - Likai Song
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32306, USA
| | - Lloyd Lumata
- Department of Physics, University of Texas at Dallas, 800 West Campbell Road, Richardson, Texas 75080, USA
| |
Collapse
|
2
|
Niedbalski P, Kiswandhi A, Parish C, Wang Q, Khashami F, Lumata L. NMR Spectroscopy Unchained: Attaining the Highest Signal Enhancements in Dissolution Dynamic Nuclear Polarization. J Phys Chem Lett 2018; 9:5481-5489. [PMID: 30179503 DOI: 10.1021/acs.jpclett.8b01687] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Dynamic nuclear polarization (DNP) via the dissolution method is one of the most successful methods for alleviating the inherently low Boltzmann-dictated sensitivity in nuclear magnetic resonance (NMR) spectroscopy. This emerging technology has already begun to positively impact chemical and metabolic research by providing the much-needed enhancement of the liquid-state NMR signals of insensitive nuclei such as 13C by several thousand-fold. In this Perspective, we present our viewpoints regarding the key elements needed to maximize the NMR signal enhancements in dissolution DNP, from the very core of the DNP process at cryogenic temperatures, DNP instrumental conditions, and chemical tuning in sample preparation to current developments in minimizing hyperpolarization losses during the dissolution transfer process. The optimization steps discussed herein could potentially provide important experimental and theoretical considerations in harnessing the best possible sensitivity gains in NMR spectroscopy as afforded by optimized dissolution DNP technology.
Collapse
Affiliation(s)
- Peter Niedbalski
- Department of Physics , The University of Texas at Dallas , 800 West Campbell Road , Richardson , Texas 75080 , United States
| | - Andhika Kiswandhi
- Department of Physics , The University of Texas at Dallas , 800 West Campbell Road , Richardson , Texas 75080 , United States
| | - Christopher Parish
- Department of Physics , The University of Texas at Dallas , 800 West Campbell Road , Richardson , Texas 75080 , United States
| | - Qing Wang
- Department of Physics , The University of Texas at Dallas , 800 West Campbell Road , Richardson , Texas 75080 , United States
| | - Fatemeh Khashami
- Department of Physics , The University of Texas at Dallas , 800 West Campbell Road , Richardson , Texas 75080 , United States
| | - Lloyd Lumata
- Department of Physics , The University of Texas at Dallas , 800 West Campbell Road , Richardson , Texas 75080 , United States
| |
Collapse
|
3
|
Parish C, Niedbalski P, Kiswandhi A, Lumata L. Dynamic nuclear polarization of carbonyl and methyl 13C spins of acetate using 4-oxo-TEMPO free radical. J Chem Phys 2018; 149:054302. [PMID: 30089385 DOI: 10.1063/1.5043378] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Hyperpolarization of 13C-enriched biomolecules via dissolution dynamic nuclear polarization (DNP) has enabled real-time metabolic imaging of a variety of diseases with superb specificity and sensitivity. The source of the unprecedented liquid-state nuclear magnetic resonance spectroscopic or imaging signal enhancements of >10 000-fold is the microwave-driven DNP process that occurs at a relatively high magnetic field and cryogenic temperature. Herein, we have methodically investigated the relative efficiencies of 13C DNP of single or double 13C-labeled sodium acetate with or without 2H-enrichment of the methyl group and using a 4-oxo-TEMPO free radical as the polarizing agent at 3.35 T and 1.4 K. The main finding of this work is that not all 13C spins in acetate are polarized with equal DNP efficiency using this relatively wide electron spin resonance linewidth free radical. In fact, the carbonyl 13C spins have about twice the solid-state 13C polarization level of methyl 13C spins. Deuteration of the methyl group provides a DNP signal improvement of methyl 13C spins on a par with that of carbonyl 13C spins. On the other hand, both the double 13C-labeled [1,2-13C2] acetate and [1,2-13C2, 2H3] acetate have a relative solid-state 13C polarization at the level of [2-13C] acetate. Meanwhile, the solid-state 13C T1 relaxation times at 3.35 T and 1.4 K were essentially the same for all six isotopomers of 13C acetate. These results suggest that the intramolecular environment of 13C spins plays a prominent role in determining the 13C DNP efficiency, while the solid phase 13C T1 relaxation of these samples is dominated by the paramagnetic effect due to the relatively high concentration of free radicals.
Collapse
Affiliation(s)
- Christopher Parish
- Department of Physics, The University of Texas at Dallas, 800 West Campbell Road, Richardson, Texas 75080, USA
| | - Peter Niedbalski
- Department of Physics, The University of Texas at Dallas, 800 West Campbell Road, Richardson, Texas 75080, USA
| | - Andhika Kiswandhi
- Department of Physics, The University of Texas at Dallas, 800 West Campbell Road, Richardson, Texas 75080, USA
| | - Lloyd Lumata
- Department of Physics, The University of Texas at Dallas, 800 West Campbell Road, Richardson, Texas 75080, USA
| |
Collapse
|
4
|
Niedbalski P, Wang Q, Parish C, Khashami F, Kiswandhi A, Lumata L. Magnetic-Field-Dependent Lifetimes of Hyperpolarized 13C Spins at Cryogenic Temperature. J Phys Chem B 2018; 122:1898-1904. [PMID: 29369632 DOI: 10.1021/acs.jpcb.8b00630] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Using a home-built cryogen-free dynamic nuclear polarization (DNP) system with a variable magnetic field capability, 13C spin-lattice T1 relaxation times of hyperpolarized [1-13C] carboxylates (sodium acetate, glycine, sodium pyruvate, and pyruvic acid) doped with trityl OX063 free radical were systematically measured for the first time at different field strengths up to 9 T at T = 1.8 K. Our data reveal that the 13C T1 values of these frozen hyperpolarized 13C samples vary drastically with the applied magnetic field B according to an apparent empirical power-law dependence (13C T1 ∝ Bα, 2.3 < α < 3.1), with relaxation values ranging from a few hundred seconds at 1 T to over 200,000 s at fields close to 9 T. This low temperature relaxation behavior can be ascribed approximately to a model that accounts for the combined effect of 13C-1H intramolecular dipolar interaction and the relaxation contribution from the paramagnetic impurities present in the DNP sample. Since the lifetime or T1 storage of the hyperpolarized state is intimately linked to DNP efficiency, these 13C relaxation data at cryogenic temperature have important theoretical and experimental implications as the DNP of 13C-labeled biomolecules is pushed to higher magnetic fields.
Collapse
Affiliation(s)
- Peter Niedbalski
- Department of Physics, The University of Texas at Dallas , 800 West Campbell Road, Richardson, Texas 75080, United States
| | - Qing Wang
- Department of Physics, The University of Texas at Dallas , 800 West Campbell Road, Richardson, Texas 75080, United States
| | - Christopher Parish
- Department of Physics, The University of Texas at Dallas , 800 West Campbell Road, Richardson, Texas 75080, United States
| | - Fatemeh Khashami
- Department of Physics, The University of Texas at Dallas , 800 West Campbell Road, Richardson, Texas 75080, United States
| | - Andhika Kiswandhi
- Department of Physics, The University of Texas at Dallas , 800 West Campbell Road, Richardson, Texas 75080, United States
| | - Lloyd Lumata
- Department of Physics, The University of Texas at Dallas , 800 West Campbell Road, Richardson, Texas 75080, United States
| |
Collapse
|
5
|
Niedbalski P, Parish C, Wang Q, Hayati Z, Song L, Martins AF, Sherry AD, Lumata L. Transition Metal Doping Reveals Link between Electron T 1 Reduction and 13C Dynamic Nuclear Polarization Efficiency. J Phys Chem A 2017; 121:9221-9228. [PMID: 29125294 PMCID: PMC5793213 DOI: 10.1021/acs.jpca.7b09448] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Optimal efficiency of dissolution dynamic nuclear polarization (DNP) is essential to provide the required high sensitivity enhancements for in vitro and in vivo hyperpolarized 13C nuclear magnetic resonance (NMR) spectroscopy and imaging (MRI). At the nexus of the DNP process are the free electrons, which provide the high spin alignment that is transferred to the nuclear spins. Without changing DNP instrumental conditions, one way to improve 13C DNP efficiency is by adding trace amounts of paramagnetic additives such as lanthanide (e.g., Gd3+, Ho3+, Dy3+, Tb3+) complexes to the DNP sample, which has been observed to increase solid-state 13C DNP signals by 100-250%. Herein, we have investigated the effects of paramagnetic transition metal complex R-NOTA (R = Mn2+, Cu2+, Co2+) doping on the efficiency of 13C DNP using trityl OX063 as the polarizing agent. Our DNP results at 3.35 T and 1.2 K show that doping the 13C sample with 3 mM Mn2+-NOTA led to a substantial improvement of the solid-state 13C DNP signal by a factor of nearly 3. However, the other transition metal complexes Cu2+-NOTA and Co2+-NOTA complexes, despite their paramagnetic nature, had essentially no impact on solid-state 13C DNP enhancement. W-band electron paramagnetic resonance (EPR) measurements reveal that the trityl OX063 electron T1 was significantly reduced in Mn2+-doped samples but not in Cu2+- and Co2+-doped DNP samples. This work demonstrates, for the first time, that not all paramagnetic additives are beneficial to DNP. In particular, our work provides a direct evidence that electron T1 reduction of the polarizing agent by a paramagnetic additive is an essential requirement for the improvement seen in solid-state 13C DNP signal.
Collapse
Affiliation(s)
- Peter Niedbalski
- Department of Physics, The University of Texas at Dallas, Richardson, TX 75080, USA
| | - Christopher Parish
- Department of Physics, The University of Texas at Dallas, Richardson, TX 75080, USA
| | - Qing Wang
- Department of Physics, The University of Texas at Dallas, Richardson, TX 75080, USA
| | - Zahra Hayati
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, USA
| | - Likai Song
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, USA
| | - André F. Martins
- Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Department of Chemistry, The University of Texas at Dallas, Richardson, TX 75080, USA
| | - A. Dean Sherry
- Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Department of Chemistry, The University of Texas at Dallas, Richardson, TX 75080, USA
| | - Lloyd Lumata
- Department of Physics, The University of Texas at Dallas, Richardson, TX 75080, USA
| |
Collapse
|