title: On The Potential of Dynamic Nuclear Polarization Enhanced Diamonds in Solid-State and Dissolution (13) C NMR Spectroscopy.
abstract: Dynamic nuclear polarization (DNP) is a versatile option to improve the sensitivity of NMR and MRI. This versatility has elicited interest for overcoming potential limitations of these techniques, including the achievement of solid-state polarization enhancement at ambient conditions, and the maximization of (13) C signal lifetimes for performing in vivo MRI scans. This study explores whether diamond's (13) C behavior in nano- and micro-particles could be used to achieve these ends. The characteristics of diamond's DNP enhancement were analyzed for different magnetic fields, grain sizes, and sample environments ranging from cryogenic to ambient temperatures, in both solution and solid-state experiments. It was found that (13) C NMR signals could be boosted by orders of magnitude in either low- or room-temperature solid-state DNP experiments by utilizing naturally occurring paramagnetic P1 substitutional nitrogen defects. We attribute this behavior to the unusually long electronic/nuclear spin-lattice relaxation times characteristic of diamond, coupled with a time-independent cross-effect-like polarization transfer mechanism facilitated by a matching of the nitrogen-related hyperfine coupling and the (13) C Zeeman splitting. The efficiency of this solid-state polarization process, however, is harder to exploit in dissolution DNP-enhanced MRI contexts. The prospects for utilizing polarized diamond approaching nanoscale dimensions for both solid and solution applications are briefly discussed.
authors.affiliation: Chemical Physics Department, Weizmann Institute of Science, Rehovot, Israel.
authors.forename: Christian O
authors.initials: CO
authors.lastname: Bretschneider
authors.affiliation: NMR Supported Structural Biology, Leibniz-Institut für Molekulare Pharmakologie, Berlin, Germany.|Aarhus Institute of Advanced Studies and Interdisciplinary Nanoscience Center, Aarhus, Denmark.
authors.forename: Ümit
authors.initials: Ü
authors.lastname: Akbey
authors.affiliation: Bruker Biospin, France.
authors.forename: Fabien
authors.initials: F
authors.lastname: Aussenac
authors.affiliation: Chemical Physics Department, Weizmann Institute of Science, Rehovot, Israel.
authors.forename: Greg L
authors.initials: GL
authors.lastname: Olsen
authors.affiliation: Chemical Physics Department, Weizmann Institute of Science, Rehovot, Israel.
authors.forename: Akiva
authors.initials: A
authors.lastname: Feintuch
authors.affiliation: NMR Supported Structural Biology, Leibniz-Institut für Molekulare Pharmakologie, Berlin, Germany.
authors.forename: Hartmut
authors.initials: H
authors.lastname: Oschkinat
authors.affiliation: Chemical Physics Department, Weizmann Institute of Science, Rehovot, Israel. lucio.frydman@weizmann.ac.il.
authors.forename: Lucio
authors.identifier: http://orcid.org/0000-0001-8208-3521
authors.initials: L
authors.lastname: Frydman
keywords: MRI; NMR; diamonds; dynamic nuclear polarization; magic angle spinning DNP