Multi- axis fields boost SABRE hyperpolarization

• 成果类型: Article
• 署名作者: Lindale, Jacob R.; Smith, Loren L.; Mammen, Mathew W.; Eriksson, Shannon L.; Everhart, Lucas M.; Warren, Warren S.
• 署名单位: Duke University; Duke University; Duke University; Duke University; Duke University
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-11640
• DOI: 10.1073/pnas.2400066121
• 发表日期: 2024-04-02
• 关键词: magnetization-transfer; polarization; complexes; catalysts; laser

摘要

The inherently low signal - to - noise ratio of NMR and MRI is now being addressed by hyperpolarization methods. For example, iridium - based catalysts that reversibly bind both parahydrogen and ligands in solution can hyperpolarize protons (SABRE) or heteronuclei (X- SABRE) on a wide variety of ligands, using a complex interplay of spin dynamics and chemical exchange processes, with common signal enhancements between 10(3 )and 10(4). This does not approach obvious theoretical limits, and further enhancement would be valuable in many applications (such as imaging mM concentration species in vivo). Most SABRE/X-SABRE implementations require far lower fields (mu T-mT) than standard magnetic resonance (>1T), and this gives an additional degree of freedom: the ability to fully modulate fields in three dimensions. However, this has been underexplored because the standard simplifying theoretical assumptions in magnetic resonance need to be revisited. Here, we take a different approach, an evolutionary strategy algorithm for numerical optimization, multi - axis computer - aided heteronuclear transfer enhancement for SABRE (MACHETE- SABRE). We find nonintuitive but highly efficient multiaxial pulse sequences which experimentally can produce a sevenfold improvement in polarization over continuous excitation. This approach optimizes polarization differently than traditional methods, thus gaining extra efficiency.