Use of dissolved hyperpolarized species in NMR: Practical considerations

Abstract

Hyperpolarization techniques that can transiently boost nuclear spin polarization are generally carried out at low temperature-as in the case of dynamic nuclear polarization-or at high temperature in the gaseous state-as in the case of optically pumped noble gases. This review aims at describing the various issues and challenges that have been encountered during dissolution of hyperpolarized species, and solutions to these problems that have been or are currently proposed in the literature. During the transport of molecules from the polarizer to the NMR detection region, and when the hyperpolarized species or a precursor of hyperpolarization (e.g. parahydrogen) is introduced into the solution of interest, several obstacles need to be overcome to keep a high level of final magnetization. The choice of the magnetic field, the design of the dissolution setup, and ways to isolate hyperpolarized compounds from relaxation agents will be presented. Due to the non-equilibrium character of the hyperpolarization, new NMR pulse sequences that perform better than the classical ones will be described. Finally, three applications in the field of biology will be briefly mentioned.

In-cell NMR: Why and how?

“…In the following paragraphs, we highlight some key pieces of information on d-DNP, in an attempt to popularize its capabilities (and shortcomings) for non-specialists. Dedicated experimental designs and NMR pulse sequences have been developed to exploit these dissolved hyperpolarized species, and have been reviewed recently [1697,1698].…”

In-Cell Structural Biology by NMR: The Benefits of the Atomic Scale

“…Sensitivity is the eternal Achille’s heal of NMR spectroscopy. Magnetic hyperpolarization methods (DNP, para-hydrogen) have been cheered in the last years for their theoretical game-changing signal enhancement of several ordered of magnitudes. − Their applications on live cells are however limited by the short lifetime of hyperpolarization at physiological temperature, i.e., about 1 min or less. − DNP-ssNMR has been used to characterize proteins in cellular samples . However, the current DNP-agent molecules are effective at ∼100 K or less, which provokes low spectral resolution, high costs and technicity and limits the applications.…”

Integrating Micro Process Chemistry into an NMR Spectrometer

“…The hyperpolarized gases ( 129 Xe, parahydrogen) discussed in this review are relatively hydrophobic, which is an obstacle in dissolving such gases in polar (bio-relevant) liquids [82]. Thus, various approaches have been applied to improve the uptake of gas in solutions.…”