Order‐Unity 13C Nuclear Polarization of [1‐13C]Pyruvate in Seconds and the Interplay of Water and SABRE Enhancement. Issue 2 (9th December 2021)

• Record Type: Journal Article
• Authors: Adelabu, Isaiah; TomHon, Patrick; Kabir, Mohammad S. H.; Nantogma, Shiraz; Abdulmojeed, Mustapha; Mandzhieva, Iuliia; Ettedgui, Jessica; Swenson, Rolf E.; Krishna, Murali C.; Theis, Thomas; Goodson, Boyd M.; Chekmenev, Eduard Y.
• Is Part Of: Chemphyschem. Volume 23:Issue 2(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-12-09
• Subjects: hyperpolarization -- NMR spectroscopy -- parahydrogen -- 13C -- pyruvate; Chemistry, Physical and theoretical -- Periodicals; 541.05
• DOI: 10.1002/cphc.202100839
• Languages: English
• ISSNs: 1439-4235

Abstract

Abstract: Signal Amplification By Reversible Exchange in SHield Enabled Alignment Transfer (SABRE‐SHEATH) is investigated to achieve rapid hyperpolarization of 13 C1 spins of [1‐ 13 C]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 H2 O. Order‐unity 13 C (>50 %) polarization of catalyst‐bound [1‐ 13 C]pyruvate is achieved in less than 30 s by restricting the chemical exchange of [1‐ 13 C]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 CD3 OD. Efficient 13 C polarization is also enabled by favorable relaxation dynamics in sub‐microtesla magnetic fields, as indicated by fast polarization buildup rates compared to the T 1 spin‐relaxation rates (e. g., ∼0.2 s −1 versus ∼0.1 s −1, respectively, for a 6 mM catalyst‐[1‐ 13 C]pyruvate sample). Finally, the catalyst‐bound hyperpolarized [1‐ 13 C]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‐ 13 C]pyruvate produced via comparatively fast and simple SABRE‐SHEATH‐based approaches. Abstract : Highly polarized : Order unity 13 C polarization for [1‐ 13 C]pyruvate was demonstrated for catalyst‐bound species by SABRE‐SHEATH, which becomes possible due to favorable 13 C relaxation dynamics in a microtesla magnetic field. The magnetic field, temperature, and co‐solvents heavily modulate the attainable 13 C polarization, providing an opportunity for optimization to deliver highly polarized [1‐ 13 C]pyruvate quickly and cheaply for biomedical and other applications.