Optimal Glass-Forming Solvent Brings Sublimation Dynamic Nuclear Polarization to 129Xe Hyperpolarization Biomedical Imaging Standards

In addition to the dedicated spin exchange optical pumping (SEOP) technique, an alternative method to produce hyperpolarized xenon gas using dynamic nuclear polarization (DNP) followed by a sublimation procedure was proposed. The challenge associated with sublimation DNP is to obtain solid-state samples with the required homogeneity following the incorporation of xenon into a glass-forming solvent. We show that the maximum achievable 129Xe polarization strongly depends on the xenon concentration dissolved in the solvent and the properties of the solvent itself. Using a 5-T home-built polarizer, the 129Xe spins in natural abundance xenon were polarized up to 30% in about 90 min at 1.15±0.05 K. The gas was subsequently extracted to perform 129Xe MRI in a distant 9.4-T rodent scanner. We demonstrate that by careful optimization of the sample preparation, sublimation DNP can be used to hyperpolarize 129Xe at a polarization level and quantities that are sufficiently large for biomedical applications.