- Knecht, Stephan;
- Blanchard, John W;
- Barskiy, Danila;
- Cavallari, Eleonora;
- Dagys, Laurynas;
- Van Dyke, Erik;
- Tsukanov, Maksim;
- Bliemel, Bea;
- Münnemann, Kerstin;
- Aime, Silvio;
- Reineri, Francesca;
- Levitt, Malcolm H;
- Buntkowsky, Gerd;
- Pines, Alexander;
- Blümler, Peter;
- Budker, Dmitry;
- Eills, James
Hyperpolarized fumarate is a promising biosensor for carbon-13 magnetic resonance metabolic imaging. Such molecular imaging applications require nuclear hyperpolarization to attain sufficient signal strength. Dissolution dynamic nuclear polarization is the current state-of-the-art methodology for hyperpolarizing fumarate, but this is expensive and relatively slow. Alternatively, this important biomolecule can be hyperpolarized in a cheap and convenient manner using parahydrogen-induced polarization. However, this process requires a chemical reaction, and the resulting solutions are contaminated with the catalyst, unreacted reagents, and reaction side-product molecules, and are hence unsuitable for use in vivo. In this work we show that the hyperpolarized fumarate can be purified from these contaminants by acid precipitation as a pure solid, and later redissolved to a desired concentration in a clean aqueous solvent. Significant advances in the reaction conditions and reactor equipment allow for formation of hyperpolarized fumarate at 13C polarization levels of 30-45%.