|Title||Rapid Catalyst Capture Enables Metal-Free para-Hydrogen-Based Hyperpolarized Contrast Agents|
|Publication Type||Journal Article|
|Year of Publication||2018|
|Authors||Barskiy DA, Ke LA, Li X, Stevenson V, Widarman N, Zhang H, Truxal A, Pines A|
|Journal||The Journal of Physical Chemistry Letters|
Hyperpolarization techniques based on the use of para-hydrogen provide orders of magnitude signal enhancement for magnetic resonance spectroscopy and imaging. The main drawback limiting widespread applicability of para-hydrogen-based techniques in biomedicine is the presence of organometallic compounds (the polarization transfer catalysts) in solution with hyperpolarized contrast agents. These catalysts are typically complexes of platinum-group metals, and their administration in vivo should be avoided. Herein, we show how extraction of a hyperpolarized compound from an organic phase to an aqueous phase combined with a rapid (less than 10 s) Ir-based catalyst capture by metal scavenging agents can produce pure para-hydrogen-based hyperpolarized contrast agents, as demonstrated by high-resolution nuclear magnetic resonance (NMR) spectroscopy and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The presented methodology enables fast and efficient means of producing pure hyperpolarized aqueous solutions for biomedical and other uses.