Design of a 15N Molecular Unit to Achieve Long Retention of Hyperpolarized Spin State

Nuclear hyperpolarization is a phenomenon that can be used to improve the sensitivity of magnetic resonance molecular sensors. However, such sensors typically suffer from short hyperpolarization lifetime. Herein we report that [N-15, D-14] trimethylphenylammonium (TMPA) has a remarkably long spin-lattice relaxation time (1128 s, 14.1 T, 30 degrees C, D2O) on its N-15 nuclei and achieves a long retention of the hyperpolarized state. [N-15, D-14] TMPA-based hyperpolarized sensor for carboxylesterase allowed the highly sensitive analysis of enzymatic reaction by N-15 NMR for over 40 min in phophate-buffered saline (H2O, pH 7.4, 37 degrees C).