Hyperpolarized DNP-NMR
E. Monteagudo, A. Virgili, T. Parella and M. Pérez-Trujillo
Analytical Chemistry, 89, 4939-4944 (2017). DOI
Chiral Recognition by Dissolution DNP NMR Spectroscopy of 13C-Labeled dl-Methionine
A method based on d-DNP NMR spectroscopy to study chiral recognition is described for the first time. The enantiodifferentiation of a racemic metabolite in a millimolar aqueous solution using a chiral solvating agent was performed. Hyperpolarized 13C-labeled dl-methionine enantiomers were differently observed with a single-scan 13C NMR experiment, while the chiral auxiliary at thermal equilibrium remained unobserved. The method developed entails a step forward in the chiral recognition of small molecules by NMR spectroscopy, opening new possibilities in situations where the sensitivity is limited, for example, when a low concentration of analyte is available or when the measurement of an insensitive nucleus, like 13C, is required. The advantages and current limitations of the method, as well as future perspectives, are discussed.
J. L. Muñoz-Gómez, E. Monteagudo, V. Lloveras, T. Parella, J. Veciana and J. Vidal-Gancedo
RSC Advances, 6, 27077-27082 (2016). DOI
Optimized polarization build-up times in dissolution DNP-NMR using a benzyl amino derivative of BDPA
The synthesis of two novel BDPA-like radicals, a benzyl amino (BAm-BDPA, 7) and a cyano (CN-BDPA, 5) derivative, is reported and their behaviour as polarizing agents for fast dissolution Dynamic Nuclear Polarization (DNP) is evaluated. The radical 7 is a promising candidate for DNP studies since it is soluble in neat [1-13C]pyruvic acid (PA), and therefore the use of an additional glassing agent for sample homogeneity is avoided. In addition, a 60 mM sample of 7 offers optimum 13C NMR signal enhancements using fairly short polarization times (about 1800 s). It is shown that DNP-NMR measurements using 7 can be performed much more efficiently in terms of the signal enhancement per polarization build-up time unit than when using the reference OX63 or BDPA radicals. These enhanced features are translated to a substantial reduction of polarization times that represents an optimum temporary use of the DNP polarizer and allow economized liquid helium consumption.
J. L. Muñoz-Gómez, E. Monteagudo, V. Lloveras, T. Parella, J. Veciana and J. Vidal-Gancedo
Org. Biomol. Chem., 13, 2689-2693 (2015). DOI
A benzyl alcohol derivative of the BDPA radical for fast dissolution dynamic nuclear polarization NMR spectroscopy
A new polarizing agent for Dynamic Nuclear Polarization (BA-BDPA) is described. It meets all the requirements to become a promising candidate for its use in in vivo DNP-NMR experiments: it is soluble in neat [1-13C]pyruvic acid, insoluble in the dissolution transfer solvent and is effective as a polarizing agent in fast dissolution DNP-NMR applications, without the need for using glassing agents. Moreover, it enables a simple but effective in-line radical filtration to obtain hyperpolarized solutions of [1-13C]- pyruvic acid free of radicals that offers a better polarization performance.