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Hyperpolarized 13C Metabolic Magnetic Resonance Spectroscopy and Imaging
Published on: December 30, 2016
High-field 13C dynamic nuclear polarization with a radical mixture.
Vladimir K Michaelis1, Albert A Smith, Björn Corzilius
1Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Journal of the American Chemical Society
|February 5, 2013
Summary
We achieved over 600-fold (13)C enhancements using direct dynamic nuclear polarization (DNP) with optimized radicals. This advance benefits studies of biological solids and nonprotonated materials, especially in dissolution DNP applications.
Area of Science:
- Solid-state Nuclear Magnetic Resonance (NMR) spectroscopy
- Dynamic Nuclear Polarization (DNP) enhancement techniques
- Electron Paramagnetic Resonance (EPR) spectroscopy
Background:
- Dynamic Nuclear Polarization (DNP) significantly enhances NMR signal sensitivity.
- Optimizing radical properties, such as Electron Paramagnetic Resonance (EPR) linewidth and electron relaxation times, is crucial for efficient DNP.
- Direct (13)C DNP offers a pathway to enhance signals from specific carbon nuclei.
Purpose of the Study:
- To report direct (13)C dynamic nuclear polarization (DNP) at 5 Tesla (T) and 82 Kelvin (K).
- To investigate the impact of radical selection on (13)C DNP efficiency.
- To achieve significant (13)C polarization enhancements for advanced NMR applications.
Main Methods:
- Utilized direct (13)C DNP at 5 T under magic-angle spinning (MAS) conditions at 82 K.
- Employed a mixture of monoradicals, specifically SA-BDPA and trityl radicals, known for narrow EPR linewidths.
- Systematically studied the influence of EPR linewidth and electron relaxation times on polarization enhancement.
Main Results:
- Achieved substantial (13)C NMR signal enhancements exceeding 600-fold.
- Demonstrated the critical role of optimizing both EPR linewidth and electron relaxation times for direct (13)C DNP.
- Successfully applied DNP using SA-BDPA and trityl radicals for direct (13)C polarization.
Conclusions:
- Direct (13)C DNP with optimized monoradicals provides a powerful method for signal enhancement.
- This technique is particularly suitable for dissolution DNP and the study of (1)H-depleted biological and nonprotonated solid materials.
- The findings pave the way for improved NMR investigations in challenging sample systems.
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