Order-Unity 13C Nuclear Polarization of [1-13C]Pyruvate in Seconds and the Interplay of Water and SABRE Enhancement |
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Authors: | Isaiah Adelabu Patrick TomHon Mohammad S H Kabir Shiraz Nantogma Mustapha Abdulmojeed Iuliia Mandzhieva Dr Jessica Ettedgui Dr Rolf E Swenson Dr Murali C Krishna Prof Thomas Theis Prof Boyd M Goodson Prof Eduard Y Chekmenev |
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Institution: | 1. Integrative Biosciences, Department of Chemistry Karmanos Cancer Institute, Wayne State University, 5101 Cass Ave, Detroit, MI, 48202 USA;2. Department of Chemistry, North Carolina State University, Raleigh, North Carolina, 27695-8204 USA;3. Chemistry and Synthesis Center, National Heart, Lung, and Blood Institute, 9800 Medical Center Drive, Building B, Room #2034, Bethesda, Maryland, 20850 USA;4. Center for Cancer Research, National Cancer Institute, Bethesda, 31 Center Drive, Maryland, 20814 USA;5. School of Chemical and Biomolecular Sciences Materials Technology Center, Southern Illinois University, 1245 Lincoln Dr., Carbondale, IL, 62901 USA |
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Abstract: | Signal Amplification By Reversible Exchange in SHield Enabled Alignment Transfer (SABRE-SHEATH) is investigated to achieve rapid hyperpolarization of 13C1 spins of 1-13C]pyruvate, using parahydrogen as the source of nuclear spin order. Pyruvate exchange with an iridium polarization transfer complex can be modulated via a sensitive interplay between temperature and co-ligation of DMSO and H2O. Order-unity 13C (>50 %) polarization of catalyst-bound 1-13C]pyruvate is achieved in less than 30 s by restricting the chemical exchange of 1-13C]pyruvate at lower temperatures. On the catalyst bound pyruvate, 39 % polarization is measured using a 1.4 T NMR spectrometer, and extrapolated to >50 % at the end of build-up in situ. The highest measured polarization of a 30-mM pyruvate sample, including free and bound pyruvate is 13 % when using 20 mM DMSO and 0.5 M water in CD3OD. Efficient 13C polarization is also enabled by favorable relaxation dynamics in sub-microtesla magnetic fields, as indicated by fast polarization buildup rates compared to the T1 spin-relaxation rates (e. g., ∼0.2 s−1 versus ∼0.1 s−1, respectively, for a 6 mM catalyst-1-13C]pyruvate sample). Finally, the catalyst-bound hyperpolarized 1-13C]pyruvate can be released rapidly by cycling the temperature and/or by optimizing the amount of water, paving the way to future biomedical applications of hyperpolarized 1-13C]pyruvate produced via comparatively fast and simple SABRE-SHEATH-based approaches. |
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Keywords: | hyperpolarization NMR spectroscopy parahydrogen 13C pyruvate |
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