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Radio-Frequency Sweeps at Microtesla Fields for Parahydrogen-Induced Polarization of Biomolecules

2023; American Chemical Society; Volume: 14; Issue: 8 Linguagem: Inglês

10.1021/acs.jpclett.2c03785

1948-7185

Alastair Marshall, Alon Salhov, Martin Gierse, Christoph Müller, Michael Keim, Sebastian Lucas, Anna J. Parker, Jochen Scheuer, Christophoros C. Vassiliou, Philipp Neumann, Fedor Jelezko, Alex Retzker, John W. Blanchard, Ilai Schwartz, Stephan Knecht,

NMR spectroscopy and applications

Magnetic resonance imaging of 13C-labeled metabolites enhanced by parahydrogen-induced polarization (PHIP) enables real-time monitoring of processes within the body. We introduce a robust, easily implementable technique for transferring parahydrogen-derived singlet order into 13C magnetization using adiabatic radio frequency sweeps at microtesla fields. We experimentally demonstrate the applicability of this technique to several molecules, including some molecules relevant for metabolic imaging, where we show significant improvements in the achievable polarization, in some cases reaching above 60% nuclear spin polarization. Furthermore, we introduce a site-selective deuteration scheme, where deuterium is included in the coupling network of a pyruvate ester to enhance the efficiency of the polarization transfer. These improvements are enabled by the fact that the transfer protocol avoids relaxation induced by strongly coupled quadrupolar nuclei.