TY - JOUR
T1 - 1H-decoupling and Isotopic Labeling for the Measurement of the Longitudinal Relaxation Time of Hyperpolarized 13C-Methylenes in Choline Analogs
AU - Uppala, Sivaranjan
AU - Gamliel, Ayelet
AU - Harris, Talia
AU - Sosna, Jacob
AU - Gomori, J. Moshe
AU - Jerschow, Alexej
AU - Katz-Brull, Rachel
PY - 2019/11/1
Y1 - 2019/11/1
N2 - The T1 of a hyperpolarized site in solution is a key parameter that determines the time-window in which its NMR signals are observable. For 13C sites adjacent to protons, 1H-decoupling has been shown to increase the hyperpolarized signal resolution and SNR. Additionally, polarization transfer to protons has shown utility in increasing the sensitivity of detection. However, 1H-decoupling could lead to a change in the decay rate of a hyperpolarized 13C site. Here we tested this possible effect in a case where the protons are directly bound to an sp3 hyperpolarized 13C site (using [1,2-13C2]choline) and 1H-decoupling was applied continuously throughout the hyperpolarized decay measurement. We found that 1H-decoupling did not lead to any significant changes in the 13C polarization decay time but did result in the expected collapse of J-coupling and produced sharper signals. This result suggested that 1H-decoupling did not affect the decay rate of hyperpolarized sp3 13C sites. The deuterium-substitution approach (using [1,1,2,2-D4,1-13C]choline) showed a dramatic prolongation of T1. Upper bounds on the T1 of all investigated sites were calculated.
AB - The T1 of a hyperpolarized site in solution is a key parameter that determines the time-window in which its NMR signals are observable. For 13C sites adjacent to protons, 1H-decoupling has been shown to increase the hyperpolarized signal resolution and SNR. Additionally, polarization transfer to protons has shown utility in increasing the sensitivity of detection. However, 1H-decoupling could lead to a change in the decay rate of a hyperpolarized 13C site. Here we tested this possible effect in a case where the protons are directly bound to an sp3 hyperpolarized 13C site (using [1,2-13C2]choline) and 1H-decoupling was applied continuously throughout the hyperpolarized decay measurement. We found that 1H-decoupling did not lead to any significant changes in the 13C polarization decay time but did result in the expected collapse of J-coupling and produced sharper signals. This result suggested that 1H-decoupling did not affect the decay rate of hyperpolarized sp3 13C sites. The deuterium-substitution approach (using [1,1,2,2-D4,1-13C]choline) showed a dramatic prolongation of T1. Upper bounds on the T1 of all investigated sites were calculated.
KW - Carbon-13
KW - T1
KW - dynamic nuclear polarization
KW - polarization transfer
KW - proton decoupling
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U2 - 10.1002/ijch.201900016
DO - 10.1002/ijch.201900016
M3 - Article
AN - SCOPUS:85065104846
VL - 59
SP - 1014
EP - 1019
JO - Israel Journal of Chemistry
JF - Israel Journal of Chemistry
SN - 0021-2148
IS - 11-12
ER -