A Mobile DNP Polarizer for Clinical Applications

Abstract

Abstract. A mobile and low-cost apparatus for dynamic nuclear polarization (DNP) hyperpolarization based on a Halbach magnet is presented and its performance is demonstrated at room temperature and with three different radical species dissolved in a glycerol-water mixture. DNP enhancement factors for a triarylmethyl-based radical, TEMPOL and a polyelectrolyte spin-labeled with nitroxide radicals are measured as a function of the microwave power, and the extrapolated maximum enhancement factors are compared. The spin-labeled polyelectrolyte shows the best DNP efficiency and 1 H DNP enhancement factors up to #50 were observed and a maximum enhancement factor of #80 was projected. The results demonstrate that with the new mobile apparatus reliable DNP experiments can be performed with reasonably high 1 H-DNP enhancements.

Spin‐Labeled Heparins as Polarizing Agents for Dynamic Nuclear Polarization

“…This T 2e effect was already observed earlier by our group for another polyelectrolyte. [7] The elevated rotational correlation times can be ruled out as the origin of the extra-saturation as SL-heparin 1 and 4 are identical systems which differ only in the labeling degree.…”

Hyperpolarization: Sensitivity Boost in Magnetic Resonance Spectroscopy and Imaging

“…The first dissolution DNP (D-DNP) was reported in 2003 by Ardenkjaer-Larsen and coworkers where a high level of nuclear spin polarization of 13 C-labeled urea (37 % polarization) was achieved by the DNP process and fast dissolution set-up. 18 Instrumental features of the D-DNP are that: (i) polarization increments at low magnetic fields (~ 3.4 T) and cryogenic temperatures (1.1 ~ 1.5 K), (ii) data acquisition at higher magnetic fields (> 9.4 T) and room temperatures followed by a fast dissolution process.…”

“…However, caused by several orders of signal enhancement, D-DNP method makes it possible to study the non-equilibrium reactions while the reactions carried on. Hilty group initially presented a time-resolved 13 C DNP-NMR spectroscopy where the real-time enzyme catalyzed reaction was examined under near-physiological conditions. 24 The process was monitored by observing consumption of the reactant and formation of products by using a small flip angle pulse scheme.…”

“…On the basis of Griffin's pioneering work in DNP-MAS spectroscopy, the SS-DNP technique has been extensively applied to study several different bio-macromolecules like amyloid fibers, peptides, membrane proteins, and bacteriophases. In addition to the one dimensional (1D) SS-DNP experiments, several two dimensional (2D) homo/heteronuclear correlation spectroscopy ( 1 H-13 C, 13 C-13 C, and 15 N-13 C) were proposed. Since the 2D correlation spectroscopy provides a spin connectivity, the method can potentially be used for investigations of resonance assignments and intermolecular structures of proteins.…”

“…The saturation factor explains the degree of saturation of the electron transitions by the influence of the microwave irradiation. Since the overall polarization enhancement becomes to be less efficient at a high magnetic field strength, the polarization process and data acquisition in O-DNP method are usually conducted at low magnetic fields near ~ 0.3 T. 13 In addition, several groups proposed continuous flowing / shuttling technique where hyperpolarization first takes place in a low magnetic field (0.23 T ~ 0.34 T), and the NMR data is acquired in a high magnetic field (4.7 T ~ 14.09 T) by transferring the polarized sample.…”