Hyperpolarized 15N-labeled, deuterated tris (2-pyridylmethyl)amine as an MRI sensor of freely available Zn2.

Dynamic nuclear polarization (DNP) coupled with 15N magnetic resonance imaging (MRI) provides an opportunity to image quantitative levels of biologically important metal ions such as Zn2+, Mg2+ or Ca2+ using appropriately designed 15N enriched probes. For example, a Zn-specific probe could prove particularly valuable for imaging the tissue distribution of freely available Zn2+ ions, an important known metal ion biomarker in the pancreas, in prostate cancer, and in several neurodegenerative diseases. In the present study, we prepare the cell-permeable, 15N-enriched, d6-deuterated version of the well-known Zn2+ chelator, tris(2-pyridylmethyl)amine (TPA) and demonstrate that the polarized ligand had favorable T1 and linewidth characteristics for 15N MRI. Examples of how polarized TPA can be used to quantify freely available Zn2+ in homogenized human prostate tissue and intact cells are presented.