Signal Amplification by Reversible-Exchange (SABRE) is a method of hyperpolarizing substrates by polarization transfer from para-hydrogen without hydrogenation. Here, we demonstrate that this method can be applied to hyperpolarize small amounts of all proteinogenic amino acids and some chosen peptides down to the nanomole regime and can be detected in a single scan in low-magnetic fields down to 0.25 mT (10 kHz proton frequency). An outstanding feature is that depending on the chemical state of the used catalyst and the investigated amino acid or peptide, hyperpolarized hydrogen-deuterium gas is formed, which was detected with (1)H and (2)H NMR spectroscopy at low magnetic fields of B(0) = 3.9 mT (166 kHz proton frequency) and 3.2 mT (20 kHz deuterium frequency).

Signal Amplification By Reversible Exchange (SABRE) is an inexpensive, fast, and even continuous hyperpolarization technique that uses para-hydrogen as hyperpolarization source. However, current SABRE faces a number of stumbling blocks for translation to biochemical and clinical settings. Difficulties include inefficient polarization in in water, relatively short lived 1H-polarization, and relatively limited substrate scope. Here we use a water soluble polarization transfer catalyst to hyperpolarize nitrogen-15 in a variety of molecules with SABRE-SHEATH (SABRE in Shield Enables Alignment Transfer to Heteronuclei). This strategy works in pure H2O or D2O solutions, on substrates that could not be hyperpolarized in traditional 1H-SABRE experiments, and we record 15N T1 relaxation times of up to 2 min.

We introduce two experiments that allow for the rapid production of hyperpolarized metabolites. More than 50% 13C polarization in 50 mM concentrations is achieved. This can be translated to portable low field NMR devices.

NMR signal amplification by reversible exchange (SABRE) has been observed for pyridine, methyl nicotinate, N-methylnicotinamide, and nicotinamide in D 2 Ow ith the new catalyst[ Ir(Cl)(IDEG)(COD)] (IDEG = 1,3-bis(3,4,5-tris(diethyleneglycol)benzyl)imidazole-2-ylidene). During the activation and hyperpolarization steps, exclusively D 2 Ow as used, resulting in the first fully biocompatible SABRE system. Hyperpolarized 1 Hs ubstrate signals wereo bserved at 42.5 MHz upon pressurizing the solutionw ith parahydrogen at close to the Earth's magnetic field, at concentrations yielding barely detectablet hermals ignals. Moreover,4 2-, 26-, 22-, and 9-fold enhancements wereo bserved for nicotinamide, pyridine, methyl nicotinate, and N-methylnicotinamide, respectively,i nc onventional 300 MHz studies. This research opens up new opportunities in af ield in which SABRE has hitherto primarilyb een conducted in CD 3 OD.T his system uses simple hardware, leaves the substrate unaltered, and shows that SABRE is potentially suitable for clinical purposes.