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2823807 
Journal Article 
Hybrid polarizing solids for pure hyperpolarized liquids through dissolution dynamic nuclear polarization 
Gajan, D; Bornet, A; Vuichoud, B; Milani, J; Melzi, R; van Kalkeren, HA; Veyre, L; Thieuleux, C; Conley, MP; Grüning, WR; Schwarzwälder, M; Lesage, A; Copéret, C; Bodenhausen, G; Emsley, L; Jannin, S 
2014 
1 
Proceedings of the National Academy of Sciences of the United States of America
ISSN: 0027-8424
EISSN: 1091-6490 
National Academy of Sciences 
111 
41 
14693-14697 
English 
25267650 
WOS:000342922000031 
Hyperpolarization of substrates for magnetic resonance spectroscopy (MRS) and imaging (MRI) by dissolution dynamic nuclear polarization (D-DNP) usually involves saturating the ESR transitions of polarizing agents (PAs; e.g., persistent radicals embedded in frozen glassy matrices). This approach has shown enormous potential to achieve greatly enhanced nuclear spin polarization, but the presence of PAs and/or glassing agents in the sample after dissolution can raise concerns for in vivo MRI applications, such as perturbing molecular interactions, and may induce the erosion of hyperpolarization in spectroscopy and MRI. We show that D-DNP can be performed efficiently with hybrid polarizing solids (HYPSOs) with 2,2,6,6-tetramethyl-piperidine-1-oxyl radicals incorporated in a mesostructured silica material and homogeneously distributed along its pore channels. The powder is wetted with a solution containing molecules of interest (for example, metabolites for MRS or MRI) to fill the pore channels (incipient wetness impregnation), and DNP is performed at low temperatures in a very efficient manner. This approach allows high polarization without the need for glass-forming agents and is applicable to a broad range of substrates, including peptides and metabolites. During dissolution, HYPSO is physically retained by simple filtration in the cryostat of the DNP polarizer, and a pure hyperpolarized solution is collected within a few seconds. The resulting solution contains the pure substrate, is free from any paramagnetic or other pollutants, and is ready for in vivo infusion. 
Nuclear magnetic resonance--NMR; Silicas; Spectrum analysis; Dissolution; Metabolites; Substrates; 2014)