A novel sample handling system for dissolution dynamic nuclear polarization experiments

Abstract

Abstract. We present a system for facilitated sample vitrification, melting, and transfer in dissolution dynamic nuclear polarization (DDNP) experiments. In DDNP, a sample is typically hyperpolarized at cryogenic temperatures before dissolution with hot solvent and transfer to a nuclear magnetic resonance (NMR) spectrometer for detection in the liquid state. The resulting signal enhancements can exceed 4 orders of magnitude. However, the sudden temperature jump from cryogenic temperatures close to 1 K to ambient conditions imposes a particular challenge. It is necessary to rapidly melt the sample to avoid a prohibitively fast decay of hyperpolarization. Here, we demonstrate a sample dissolution method that facilitates the temperature jump by eliminating the need to open the cryostat used to cool the sample. This is achieved by inserting the sample through an airlock in combination with a dedicated dissolution system that is inserted through the same airlock shortly before the melting event. The advantages are threefold: (1) the cryostat can be operated continuously at low temperatures. (2) The melting process is rapid as no pressurization steps of the cryostat are required. (3) Blockages of the dissolution system due to freezing of solvents during melting and transfer are minimized.

A cryogen-free, semi-automated apparatus for bullet-dynamic nuclear polarization with improved resolution

“…A key advantage of this system is that it does not consume liquid helium. This magnet system is available commercially from Cryogenic Ltd., UK, and has been installed successfully in several labs Kress et al, 2021).…”

Toward protein NMR at physiological concentrations by hyperpolarized water—Finding and mapping uncharted conformational spaces

“…In brief, hyperpolarized water was produced in a dedicated DNP apparatus under cryogenic conditions ( T DNP = 1.3 K) by microwave irradiation of dissolved stable radicals [15 mM TEMPOL (4-Hydroxy-2,2,6,6-tetramethylpiperidinyloxyl]. To this end, we used the home-built prototype described by Kress et al ( 41 ). After polarization buildup, the hyperpolarized water was rapidly heated to ambient temperatures and pneumatically transferred to an NMR spectrometer where a MAX solution was waiting “in situ” in the NMR tube.…”

“…50 mW. The magnet-cryostat combination was purchased from Cryogenic Ltd. and operated as described in ( 41 ).…”

Inversion of Hyperpolarized 13C NMR Signals through Cross-Correlated Cross-Relaxation in Dissolution DNP Experiments

“…30 cm above the bores of the polarizer and NMR magnets. Between the polarizer and the entrance to the tunnel, a pulsed solenoidal magnet 32 has been used in some experiments, providing a field of B Solenoid > 0.2 T. Likewise, the space between the exit from the tunnel and the entrance of the bore of the NMR magnet could be bridged by a pulsed solenoid 32 if desired. The pulsed solenoids ended ca.…”

“…In Vienna, the DDNP experiments were performed as described in ref ( 32 ). In brief, 100 μL of a paramagnetically doped methanol/glycerol sample was hyperpolarized for 1 h at 1.4 K in a magnetic field of B 0,DNP = 6.7 T either positively at a microwave frequency of 188.08 GHz or negatively at a frequency 188.4 GHz.…”