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Dissolution Dynamic Nuclear Polarization Instrumentation for Real-time Enzymatic Reaction Rate Measurements by NMR
Published on: February 23, 2016
Low-temperature dynamic nuclear polarization at 9.4 T with a 30 mW microwave source
Kent R Thurber1, Wai-Ming Yau, Robert Tycko
1Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0520, USA.
Journal of Magnetic Resonance (San Diego, Calif. : 1997)
|April 16, 2010
Summary
Dynamic nuclear polarization (DNP) significantly enhances nuclear magnetic resonance (NMR) signals. Experiments show DNP can boost (1)H NMR signals by up to 80-fold, with field modulation further increasing polarization.
Area of Science:
- Magnetic Resonance Spectroscopy
- Physical Chemistry
- Materials Science
Background:
- Dynamic nuclear polarization (DNP) enhances nuclear magnetic resonance (NMR) sensitivity via electron-to-nuclear spin polarization transfer.
- High magnetic fields (9.4 T) and low temperatures (7-80 K) are crucial for efficient DNP.
Purpose of the Study:
- To investigate DNP performance at 9.4 T using a tunable microwave source and quasi-optical bridge.
- To evaluate the impact of dopants, field modulation, and experimental parameters on DNP efficiency.
Main Methods:
- Experiments conducted at 9.4 T (264 GHz electron frequency) and 7-80 K.
- Utilized a 30 mW frequency-tunable microwave source and quasi-optical bridge.
- Employed frozen glycerol/water doped with nitroxide radicals, including a novel triradical (DOTOPA-TEMPO).
Main Results:
- Achieved DNP signal enhancements up to a factor of 80 for (1)H NMR.
- Observed maximum sensitivity enhancements with the DOTOPA-TEMPO triradical dopant.
- Field modulation increased nuclear spin polarization by up to 135%.
Conclusions:
- Low-temperature DNP dramatically increases (1)H spin polarization (approx. 1000-fold at 7 K vs. 80 K thermal).
- DNP parameters like dopant type, concentration, temperature, and microwave power significantly influence signal enhancement.
- Field modulation is a valuable technique for further boosting DNP efficiency.
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