@article{mcbride_macculloch_tomhon_browning_meisel_abdulmojeed_goodson_chekmenev_theis_2024, title={Carbon-13 Hyperpolarization of α-Ketocarboxylates with Parahydrogen in Reversible Exchange}, volume={12}, ISSN={["1860-7187"]}, url={https://doi.org/10.1002/cmdc.202400378}, DOI={10.1002/cmdc.202400378}, abstractNote={Signal Amplification by Reversible Exchange (SABRE) is a relatively simple and fast hyperpolarization technique that has been used to hyperpolarize the α‐ketocarboxylate pyruvate, a central metabolite and the leading hyperpolarized MRI contrast agent. In this work, we show that SABRE can readily be extended to hyperpolarize 13C nuclei at natural abundance on many other α‐ketocarboxylates. Hyperpolarization is observed and optimized on pyruvate (P13C=17%) and 2‐oxobutyrate (P13C=25%) with alkyl chains in the R‐group, oxaloacetate (P13C=11%) and alpha‐ketoglutarate (P13C=13%) with carboxylate moieties in the R group, and phenylpyruvate (P13C=2%) and phenylglyoxylate (P13C=2%) with phenyl rings in the R‐group. New catalytically active SABRE binding motifs of the substrates to the hyperpolarization transfer catalyst—particularly for oxaloacetate—are observed. We experimentally explore the connection between temperature and exchange rates for all of these SABRE systems and develop a theoretical kinetic model, which is used to fit the hyperpolarization build‐up and decay during SABRE activity.}, journal={CHEMMEDCHEM}, author={Mcbride, Stephen J. and Macculloch, Keilian and Tomhon, Patrick and Browning, Austin and Meisel, Samantha and Abdulmojeed, Mustapha and Goodson, Boyd M. and Chekmenev, Eduard Y. and Theis, Thomas}, year={2024}, month={Dec} }
 @article{adelabu_nantogma_fleischer_abdulmojeed_maissin_schmidt_lehmkuhl_rosen_appelt_theis_et al._2024, title={Toward Ultra-High-Quality-Factor Wireless Masing Magnetic Resonance Sensing}, volume={7}, ISSN={["1521-3773"]}, DOI={10.1002/anie.202406551}, abstractNote={It has recently been shown that a bolus of hyperpolarized nuclear spins can yield stimulated emission signals similar in nature to maser signals, potentially enabling new ways of sensing hyperpolarized contrast media, including most notably [1-}, journal={ANGEWANDTE CHEMIE-INTERNATIONAL EDITION}, author={Adelabu, Isaiah and Nantogma, Shiraz and Fleischer, Simon and Abdulmojeed, Mustapha and Maissin, Henri and Schmidt, Andreas B. and Lehmkuhl, Soeren and Rosen, Matthew S. and Appelt, Stephan and Theis, Thomas and et al.}, year={2024}, month={Jul} }
 @article{macculloch_browning_bedoya_mcbride_abdulmojeed_dedesma_goodson_rosen_chekmenev_yen_et al._2023, title={Facile hyperpolarization chemistry for molecular imaging and metabolic tracking of [1-13C]pyruvate in vivo}, volume={16-17}, ISSN={["2666-4410"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85168097895&partnerID=MN8TOARS}, DOI={10.1016/j.jmro.2023.100129}, abstractNote={Hyperpolarization chemistry based on reversible exchange of parahydrogen, also known as Signal Amplification By Reversible Exchange (SABRE), is a particularly simple approach to attain high levels of nuclear spin hyperpolarization, which can enhance NMR and MRI signals by many orders of magnitude. SABRE has received significant attention in the scientific community since its inception because of its relative experimental simplicity and its broad applicability to a wide range of molecules, however in vivo detection of molecular probes hyperpolarized by SABRE has remained elusive. Here we describe a first demonstration of SABRE-hyperpolarized contrast detected in vivo, specifically using hyperpolarized [1-13C]pyruvate. Biocompatible formulations of hyperpolarized [1-13C]pyruvate in, both, methanol-water mixtures, and ethanol-water mixtures followed by dilution with saline and catalyst filtration were prepared and injected into healthy Sprague Dawley and Wistar rats. Effective hyperpolarization-catalyst removal was performed with silica filters without major losses in hyperpolarization. Metabolic conversion of pyruvate to lactate, alanine, and bicarbonate was detected in vivo. Pyruvate-hydrate was also observed as minor byproduct. Measurements were performed on the liver and kidney at 4.7 T via time-resolved spectroscopy and chemical-shift-resolved MRI. In addition, whole-body metabolic measurements were obtained using a cryogen-free 1.5 T MRI system, illustrating the utility of combining lower-cost MRI systems with simple, low-cost hyperpolarization chemistry to develop safe, and scalable molecular imaging.}, journal={JOURNAL OF MAGNETIC RESONANCE OPEN}, author={Macculloch, Keilian and Browning, Austin and Bedoya, David O. Guarin and Mcbride, Stephen J. and Abdulmojeed, Mustapha B. and Dedesma, Carlos and Goodson, Boyd M. and Rosen, Matthew S. and Chekmenev, Eduard Y. and Yen, Yi-Fen and et al.}, year={2023}, month={Dec} }
 @article{adelabu_tomhon_kabir_nantogma_abdulmojeed_mandzhieva_ettedgui_swenson_krishna_theis_et al._2021, title={Order-Unity C-13 Nuclear Polarization of [1-C-13]Pyruvate in Seconds and the Interplay of Water and SABRE Enhancement}, volume={11}, ISSN={["1439-7641"]}, url={https://doi.org/10.1002/cphc.202100839}, DOI={10.1002/cphc.202100839}, abstractNote={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 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.}, number={2}, journal={CHEMPHYSCHEM}, publisher={Wiley}, author={Adelabu, Isaiah and TomHon, Patrick and Kabir, Mohammad S. H. and Nantogma, Shiraz and Abdulmojeed, Mustapha and Mandzhieva, Iuliia and Ettedgui, Jessica and Swenson, Rolf E. and Krishna, Murali C. and Theis, Thomas and et al.}, year={2021}, month={Dec} }
 @article{tomhon_abdulmojeed_adelabu_nantogma_kabir_lehmkuhl_chekmenev_theis_2021, title={Temperature Cycling Enables Efficient C-13 SABRE-SHEATH Hyperpolarization and Imaging of [1-C-13]-Pyruvate}, volume={12}, ISSN={["1520-5126"]}, url={https://doi.org/10.1021/jacs.1c09581}, DOI={10.1021/jacs.1c09581}, abstractNote={Molecular metabolic imaging in humans is dominated by positron emission tomography (PET). An emerging nonionizing alternative is hyperpolarized MRI of 13C-pyruvate, which is innocuous and has a central role in metabolism. However, similar to PET, hyperpolarized MRI with dissolution dynamic nuclear polarization (d-DNP) is complex costly, and requires significant infrastructure. In contrast, Signal Amplification By Reversible Exchange (SABRE) is a fast, cheap, and scalable hyperpolarization technique. SABRE in SHield Enables Alignment Transfer to Heteronuclei (SABRE-SHEATH) can transfer polarization from parahydrogen to 13C in pyruvate; however, polarization levels remained low relative to d-DNP (1.7% with SABRE-SHEATH versus ≈60% with DNP). Here we introduce a temperature cycling method for SABRE-SHEATH that enables >10% polarization on [1-13C]-pyruvate, sufficient for successful in vivo experiments. First, at lower temperatures, ≈20% polarization is accumulated on SABRE catalyst-bound pyruvate, which is released into free pyruvate at elevated temperatures. A kinetic model of differential equations is developed that explains this effect and characterizes critical relaxation and buildup parameters. With the large polarization, we demonstrate the first 13C pyruvate images with a cryogen-free MRI system operated at 1.5 T, illustrating that inexpensive hyperpolarization methods can be combined with low-cost MRI systems to obtain a broadly available, yet highly sensitive metabolic imaging platform.}, number={1}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, publisher={American Chemical Society (ACS)}, author={TomHon, Patrick and Abdulmojeed, Mustapha and Adelabu, Isaiah and Nantogma, Shiraz and Kabir, Mohammad Shah Hafez and Lehmkuhl, Soren and Chekmenev, Eduard Y. and Theis, Thomas}, year={2021}, month={Dec} }