Suh, Eul Hyun, Roozbeh Eskandari, Mai T. Huynh, Gaurav Sharma, Chalermchai Khemtong, Olivier Ouari, and Zoltan Kovacs. “Chapter 1 - Hyperpolarized Tracer Design, Synthesis, and Characterization.” In Advances in Magnetic Resonance Technology and Applications, edited by Eul Hyun Suh and Zoltan Kovacs, 12:1–156. The Chemistry of Hyperpolarized Magnetic Resonance Probes. Academic Press, 2024.
https://doi.org/10.1016/B978-0-323-91842-8.00006-9.
While NMR offers valuable chemical information, its sensitivity is inherently limited. The utilization of hyperpolarized NMR techniques, however, can produce significantly enhanced NMR signals, leading to a remarkable improvement in the sensitivity of conventional NMR/MRI experiments. Currently, microwave-driven dynamic nuclear polarization (DNP) is the most commonly used HP method because it is applicable to all NMR-active nuclei. The inexorable decay of the HP signal by T1 (spin-lattice) relaxation is a severe limitation of HP-NMR/MRI technology. This chapter provides a comprehensive introduction to dissolution DNP. The topics discussed include the basic principle of DNP, the design features of commercial and custom-made polarizers, DNP sample preparation and dissolution methods, various classes of polarizing agents, common T1 relaxation mechanisms, and approaches that can slow the signal decay. NMR-active nuclei that have been subjected to DNP range from 1H to 133Cs, with special emphasis on 13C. Finally, we also give a summary of synthetic methods that have been developed for the synthesis of various 13C-labeled HP probes.