Abstract: We demonstrate the first successful hyperpolarization of ⁷⁷Se nuclei using Signal Amplification By Reversible Exchange (SABRE), applied to a biologically relevant selenium–nitrogen heterocycle, 3-methyl-[1,2,4]-selenadiazolo-[4,5-a]-pyridine-4-ium chloride (SDAP)[1]. The polarization transfer was carried out at ultralow magnetic fields (0.1 μT to 5 μT), using parahydrogen as the polarization source. Remarkably, high levels of nuclear spin polarization were obtained simultaneously for both ⁷⁷Se and ¹⁵N nuclei at their natural isotopic abundances, reaching 7.0% and 5.6%, respectively. These results enable direct detection of ¹⁵N and ⁷⁷Se signals at micromolar concentrations, using a single scan at 9.4 T, without isotopic enrichment. Mechanistic analysis revealed a tandem polarization transfer pathway, in which ⁷⁷Se polarization is relayed through scalar coupling with ¹⁵N nuclei in the SABRE polarization transfer complex. This cooperative polarization mechanism enables efficient hyperpolarization of low-γ, low-abundance heteronuclei such as ⁷⁷Se. Our findings establish microtesla SABRE as a powerful, low-cost alternative to d-DNP for enhancing multinuclear NMR sensitivity in spin systems involving multiple heteronuclei. The demonstrated method opens new avenues for studying selenium-containing compounds in organic synthesis, catalysis, and biomedical research via heteronuclear NMR. This work was supported by the Russian Science Foundation (No. 25-23-00607).

Cite: Kiryutin A.S. , Markelov D.A. , Matsulevich Z.V. , Kosenko I.D. , Kireev N.V. , Godovikov I.A. , Yurkovskaya A.V.
⁷⁷Se SABRE via tandem scalar coupling: First parahydrogen-induced hyperpolarization of selenium
Modern Development of Magnetic Resonance 29 Sep - 3 Oct 2025