Order-Unity 13C Nuclear Polarization of [1-13C]Pyruvate in Seconds and the Interplay of Water and SABRE Enhancement

Chemphyschem. 2021 Nov 23. doi: 10.1002/cphc.202100839. Online ahead of print.ABSTRACTSignal 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 are measured using 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 pro...

Source: Chemphyschem - November 23, 2021 Category: Chemistry Authors: Isaiah Adelabu Patrick TomHon Mohammad Shah Hafez Kabir Shiraz Nantogma Mustapha Abdulmojeed Iuliia Mandzhieva Jessica Ettedgui Rolf E Swenson Murali C Krishna Boyd M Goodson Thomas Theis Eduard Y Chekmenev Source Type: research