15 N Hyperpolarization by Reversible Exchange Using SABRE-SHEATH.

Journal Article (Journal Article)

NMR signal amplification by reversible exchange (SABRE) is a NMR hyperpolarization technique that enables nuclear spin polarization enhancement of molecules via concurrent chemical exchange of a target substrate and parahydrogen (the source of spin order) on an iridium catalyst. Recently, we demonstrated that conducting SABRE in microtesla fields provided by a magnetic shield enables up to 10% 15 N-polarization (Theis, T.; et al. J. Am. Chem. Soc. 2015 , 137 , 1404). Hyperpolarization on 15 N (and heteronuclei in general) may be advantageous because of the long-lived nature of the hyperpolarization on 15 N relative to the short-lived hyperpolarization of protons conventionally hyperpolarized by SABRE, in addition to wider chemical shift dispersion and absence of background signal. Here we show that these unprecedented polarization levels enable 15 N magnetic resonance imaging. We also present a theoretical model for the hyperpolarization transfer to heteronuclei, and detail key parameters that should be optimized for efficient 15 N-hyperpolarization. The effects of parahydrogen pressure, flow rate, sample temperature, catalyst-to-substrate ratio, relaxation time (T 1 ), and reversible oxygen quenching are studied on a test system of 15 N-pyridine in methanol-d 4 . Moreover, we demonstrate the first proof-of-principle 13 C-hyperpolarization using this method. This simple hyperpolarization scheme only requires access to parahydrogen and a magnetic shield, and it provides large enough signal gains to enable one of the first 15 N images (2 × 2 mm2 resolution). Importantly, this method enables hyperpolarization of molecular sites with NMR T 1 relaxation times suitable for biomedical imaging and spectroscopy.

Full Text

Duke Authors

Cited Authors

  • Truong, ML; Theis, T; Coffey, AM; Shchepin, RV; Waddell, KW; Shi, F; Goodson, BM; Warren, WS; Chekmenev, EY

Published Date

  • April 2015

Published In

Volume / Issue

  • 119 / 16

Start / End Page

  • 8786 - 8797

PubMed ID

  • 25960823

Pubmed Central ID

  • PMC4419867

Electronic International Standard Serial Number (EISSN)

  • 1932-7455

International Standard Serial Number (ISSN)

  • 1932-7447

Digital Object Identifier (DOI)

  • 10.1021/acs.jpcc.5b01799

Language

  • eng