title: Influence of Dy3+and Tb3+doping on13C dynamic nuclear polarization.
abstract: Dynamic nuclear polarization (DNP) is a technique that uses a microwave-driven transfer of high spin alignment from electrons to nuclear spins. This is most effective at low temperature and high magnetic field, and with the invention of the dissolution method, the amplified nuclear magnetic resonance (NMR) signals in the frozen state in DNP can be harnessed in the liquid-state at physiologically acceptable temperature for in vitro and in vivo metabolic studies. A current optimization practice in dissolution DNP is to dope the sample with trace amounts of lanthanides such as Gd3+or Ho3+, which further improves the polarization. While Gd3+and Ho3+have been optimized for use in dissolution DNP, other lanthanides have not been exhaustively studied for use in C13 DNP applications. In this work, two additional lanthanides with relatively high magnetic moments, Dy3+and Tb3+, were extensively optimized and tested as doping additives for C13 DNP at 3.35 T and 1.2 K. We have found that both of these lanthanides are also beneficial additives, to a varying degree, for C13 DNP. The optimal concentrations of Dy3+(1.5 mM) and Tb3+(0.25 mM) for C13 DNP were found to be less than that of Gd3+(2 mM). W-band electron paramagnetic resonance shows that these enhancements due to Dy3+and Tb3+doping are accompanied by shortening of electron T1of trityl OX063 free radical. Furthermore, when dissolution was employed, Tb3+-doped samples were found to have similar liquid-state C13 NMR signal enhancements compared to samples doped with Gd3+, and both Tb3+and Dy3+had a negligible liquid-state nuclear T1shortening effect which contrasts with the significant reduction in T1when using Gd3+. Our results show that Dy3+doping and Tb3+doping have a beneficial impact on C13 DNP both in the solid and liquid states, and that Tb3+in particular could be used as a potential alternative to Gd3+in C13 dissolution DNP experiments.
authors.affiliation: Department of Physics, University of Texas at Dallas, 800 West Campbell Road, Richardson, Texas 75080, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: Niedbalski
authors.affiliation: Department of Physics, University of Texas at Dallas, 800 West Campbell Road, Richardson, Texas 75080, USA.
authors.forename: Christopher
authors.initials: C
authors.lastname: Parish
authors.affiliation: Department of Physics, University of Texas at Dallas, 800 West Campbell Road, Richardson, Texas 75080, USA.
authors.forename: Andhika
authors.initials: A
authors.lastname: Kiswandhi
authors.affiliation: Advanced Imaging Research Center, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390, USA.
authors.forename: Leila
authors.initials: L
authors.lastname: Fidelino
authors.affiliation: Advanced Imaging Research Center, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390, USA.
authors.forename: Chalermchai
authors.initials: C
authors.lastname: Khemtong
authors.affiliation: National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA.
authors.forename: Zahra
authors.initials: Z
authors.lastname: Hayati
authors.affiliation: National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA.
authors.forename: Likai
authors.initials: L
authors.lastname: Song
authors.affiliation: Advanced Imaging Research Center, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390, USA.
authors.forename: André
authors.initials: A
authors.lastname: Martins
authors.affiliation: Advanced Imaging Research Center, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390, USA.
authors.forename: A Dean
authors.initials: AD
authors.lastname: Sherry
authors.affiliation: Department of Physics, University of Texas at Dallas, 800 West Campbell Road, Richardson, Texas 75080, USA.
authors.forename: Lloyd
authors.initials: L
authors.lastname: Lumata