Browsing by Subject "hyperpolarization"

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    ItemOpen Access
    (15)N Hyperpolarization of Imidazole-(15)N2 for Magnetic Resonance pH Sensing via SABRE-SHEATH.
    (ACS Sens, 2016-06-24) Shchepin, Roman V; Barskiy, Danila A; Coffey, Aaron M; Theis, Thomas; Shi, Fan; Warren, Warren S; Goodson, Boyd M; Chekmenev, Eduard Y
    (15)N nuclear spins of imidazole-(15)N2 were hyperpolarized using NMR signal amplification by reversible exchange in shield enables alignment transfer to heteronuclei (SABRE-SHEATH). A (15)N NMR signal enhancement of ∼2000-fold at 9.4 T is reported using parahydrogen gas (∼50% para-) and ∼0.1 M imidazole-(15)N2 in methanol:aqueous buffer (∼1:1). Proton binding to a (15)N site of imidazole occurs at physiological pH (pKa ∼ 7.0), and the binding event changes the (15)N isotropic chemical shift by ∼30 ppm. These properties are ideal for in vivo pH sensing. Additionally, imidazoles have low toxicity and are readily incorporated into a wide range of biomolecules. (15)N-Imidazole SABRE-SHEATH hyperpolarization potentially enables pH sensing on scales ranging from peptide and protein molecules to living organisms.
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    ItemOpen Access
    Direct and cost-efficient hyperpolarization of long-lived nuclear spin states on universal (15)N2-diazirine molecular tags.
    (Sci Adv, 2016-03) Theis, T; Ortiz, GX; Logan, AWJ; Claytor, KE; Feng, Y; Huhn, WP; Blum, V; Malcolmson, SJ; Chekmenev, EY; Wang, Q; Warren, WS
    Conventional magnetic resonance (MR) faces serious sensitivity limitations which can be overcome by hyperpolarization methods, but the most common method (dynamic nuclear polarization) is complex and expensive, and applications are limited by short spin lifetimes (typically seconds) of biologically relevant molecules. We use a recently developed method, SABRE-SHEATH, to directly hyperpolarize (15)N2 magnetization and long-lived (15)N2 singlet spin order, with signal decay time constants of 5.8 and 23 minutes, respectively. We find >10,000-fold enhancements generating detectable nuclear MR signals that last for over an hour. (15)N2-diazirines represent a class of particularly promising and versatile molecular tags, and can be incorporated into a wide range of biomolecules without significantly altering molecular function.