Chiavazza, E., et al., 15N-permethylated amino acids as efficient probes for MRI-DNP applications. Contrast Media Mol Imaging, 2013. 8(5): p. 417-21.
The synthesis, NMR properties and preliminary polarization tests on protonated and perdeuterated forms of alpha-trimethylglutamine (NMe3Gln), alpha-trimethylglutamate (NMe3Glu) and epsilon-trimethyllysine (NMe3Lys) are reported. The (15)N-permethylated, perdeuterated amino acids display very long (15)N-T1 values, ranging between 190 and 330 s, are well polarized by the dynamic nuclear polarization (DNP) procedure, yielding good polarization levels (10%), and appear to be well tolerated by cells and mice. The obtained results make perdeuterated amino acids excellent candidates for innovative DNP (15)N-MRI applications such as perfusion or targeting studies.