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Hyperpolarization by dissolution dynamic nuclear polarization (dDNP) has enabled promising applications in spectroscopy and imaging, but remains poorly widespread due to experimental complexity. Broad democratization of dDNP could be realized by remote preparation and distribution of hyperpolarized samples from dedicated facilities. Here we show the synthesis of hyperpolarizing polymers (HYPOPs) that can generate radical- and contaminant-free hyperpolarized samples within minutes with lifetimes exceeding hours in the solid state. HYPOPs feature tunable macroporous porosity, with porous volumes up to 80% and concentration of nitroxide radicals grafted in the bulk matrix up to 285 μmol g−1. Analytes can be efficiently impregnated as aqueous/alcoholic solutions and hyperpolarized up to P(13C) = 25% within 8 min, through the combination of 1H spin diffusion and 1H → 13C cross polarization. Solutions of 13C-analytes of biological interest hyperpolarized in HYPOPs display a very long solid-state 13C relaxation times of 5.7 h at 3.8 K, thus prefiguring transportation over long distances., Hyperpolarization by dissolution dynamic nuclear polarization has brought highly sensitive magnetic resonance to reality but there still remains severe limitations. Here the authors show an approach relying on the generation of hyperpolarizing polymers that bear a dual function.

NMR-based analysis of metabolite mixtures provides crucial information on biological systems but mostly relies on 1D 1H experiments for maximizing sensitivity. However, strong peak overlap of 1H spectra often is a limitation for the analysis of inherently complex biological mixtures. Dissolution dynamic nuclear polarization (d-DNP) improves NMR sensitivity by several orders of magnitude, which enables 13C NMR-based analysis of metabolites at natural abundance. We have recently demonstrated the successful introduction of d-DNP into a full untargeted metabolomics workflow applied to the study of plant metabolism. Here we describe the systematic optimization of d-DNP experimental settings for experiments at natural 13C abundance and show how the resolution, sensitivity, and ultimately the number of detectable signals improve as a result. We have systematically optimized the parameters involved (in a semi-automated prototype d-DNP system, from sample preparation to signal detection, aiming at providing an optimization guide for potential users of such a system, who may not be experts in instrumental development). The optimization procedure makes it possible to detect previously inaccessible protonated 13C signals of metabolites at natural abundance with at least 4 times improved line shape and a high repeatability compared to a previously reported d-DNP-enhanced untargeted metabolomic study. This extends the application scope of hyperpolarized 13C NMR at natural abundance and paves the way to a more general use of DNP-hyperpolarized NMR in metabolomics studies.

An overview of the basic magnetic properties of vanadates which represent prototypes of frustrated two-dimensional S = 1/2 antiferromagnets on a square lattice is presented. It will be shown how information on the ground state sublattice magnetization, on the static uniform susceptibility and on the frustration driven lattice distortions can be achieved by means of NMR spectroscopy and magnetization measurements. The low-energy spin excitations, investigated by means of NMR and μSR relaxation measurements, will be analysed and the anomalous very-low-frequency dynamics, originating from the degeneracy of the ground state, discussed. Finally the effects of hydrostatic pressure on the degree of frustration of the vanadates will be addressed.