Characterization of frequency-chirped dynamic nuclear polarization in rotating solids.

Autor: Judge PT; Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, United States; Department of Biochemistry, Biophysics & Structural Biology, Washington University in St. Louis, St. Louis, MO 63110, United States., Sesti EL; Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, United States., Alaniva N; Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, United States., Saliba EP; Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, United States., Price LE; Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, United States., Gao C; Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, United States., Halbritter T; Department of Chemistry, University of Iceland, Science Institute, Dunhaga 3, 107 Reykjavik, Iceland., Sigurdsson ST; Department of Chemistry, University of Iceland, Science Institute, Dunhaga 3, 107 Reykjavik, Iceland., Kyei GB; Department of Medicine, Washington University School of Medicine, St. Louis, MO 63130, United States; Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Accra, Ghana., Barnes AB; Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland; Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, United States. Electronic address: abarnes@ethz.ch.
Jazyk: angličtina
Zdroj: Journal of magnetic resonance (San Diego, Calif. : 1997) [J Magn Reson] 2020 Apr; Vol. 313, pp. 106702. Date of Electronic Publication: 2020 Feb 29.
DOI: 10.1016/j.jmr.2020.106702
Abstrakt: Continuous wave (CW) dynamic nuclear polarization (DNP) is used with magic angle spinning (MAS) to enhance the typically poor sensitivity of nuclear magnetic resonance (NMR) by orders of magnitude. In a recent publication we show that further enhancement is obtained by using a frequency-agile gyrotron to chirp incident microwave frequency through the electron resonance frequency during DNP transfer. Here we characterize the effect of chirped MAS DNP by investigating the sweep time, sweep width, center-frequency, and electron Rabi frequency of the chirps. We show the advantages of chirped DNP with a trityl-nitroxide biradical, and a lack of improvement with chirped DNP using AMUPol, a nitroxide biradical. Frequency-chirped DNP on a model system of urea in a cryoprotecting matrix yields an enhancement of 142, 21% greater than that obtained with CW DNP. We then go beyond this model system and apply chirped DNP to intact human cells. In human Jurkat cells, frequency-chirped DNP improves enhancement by 24% over CW DNP. The characterization of the chirped DNP effect reveals instrument limitations on sweep time and sweep width, promising even greater increases in sensitivity with further technology development. These improvements in gyrotron technology, frequency-agile methods, and in-cell applications are expected to play a significant role in the advancement of MAS DNP.
Competing Interests: Declaration of Competing Interest The authors declare the following competing financial interest(s): A.B.B. is the author of a patent related to this work filed by the Washington University in Saint Louis (WO2015175507A1).
(Copyright © 2020. Published by Elsevier Inc.)
Databáze: MEDLINE
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