SABRE hyperpolarisation of vitamin B3 as a function of pH

Olaru, Alexandra M.; Burns, Michael J.; Green, Gary; Duckett, Simon B.

doi:10.1039/c6sc04043h

Cited by 49 publications

(33 citation statements)

References 39 publications

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“…While the corresponding frequency shift of 15 N sites is ≈90 ppm for pH‐sensing applications (i.e. appearing to be ≈9 times greater on the ppm scale), we note that on the Hz frequency scale, these nuclei actually provide near‐equal dynamic range, because the 19 F spin has a>9‐fold greater gyromagnetic ratio compared to that of 15 N. We also note that the absolute spectral sensitivity of 19 F to changes in pH is >30 times greater than that of similar proton sites …”

Section: Figurementioning

confidence: 71%

Toward Hyperpolarized ¹⁹F Molecular Imaging via Reversible Exchange with Parahydrogen

et al. 2017

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Fluorine-19 has high NMR detection sensitivity-similar to that of protons-owing to its large gyromagnetic ratio and high natural abundance (100 %). Unlike protons, however, fluorine-19 ( F) has a negligible occurrence in biological objects, as well as a more sensitive chemical shift. As a result, in vivo F NMR spectroscopy and MR imaging offer advantages of negligible background signal and sensitive reporting of the local molecular environment. Here we report on NMR hyperpolarization of F nuclei using reversible exchange reactions with parahydrogen gas as the source of nuclear spin order. NMR signals of 3-fluoropyridine were enhanced by ≈100 fold, corresponding to 0.3 % F nuclear spin polarization (at 9.4 T), using about 50 % parahydrogen. While future optimization efforts will likely significantly increase the hyperpolarization levels, we already demonstrate the utility of F hyperpolarization for high-resolution hyperpolarized F imaging and hyperpolarized F pH sensing.

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Section: Figurementioning

confidence: 71%

Toward Hyperpolarized ¹⁹F Molecular Imaging via Reversible Exchange with Parahydrogen

et al. 2017

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“…We examined the T 1 lifetime for 15 N-Nicotinamide 39 and 15 N-CHCA, which constitute biocompatible compounds and contain 15 N in chemically different environments. 39–41 Table 2 shows the 15 N- T 1 relaxation times in D 2 O, which at 1 T exceed 1 min for both compounds.…”

Section: Resultsmentioning

confidence: 99%

Direct Hyperpolarization of Nitrogen-15 in Aqueous Media with Parahydrogen in Reversible Exchange

et al. 2017

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Signal Amplification By Reversible Exchange (SABRE) is an inexpensive, fast, and even continuous hyperpolarization technique that uses para-hydrogen as hyperpolarization source. However, current SABRE faces a number of stumbling blocks for translation to biochemical and clinical settings. Difficulties include inefficient polarization in in water, relatively short lived 1H-polarization, and relatively limited substrate scope. Here we use a water soluble polarization transfer catalyst to hyperpolarize nitrogen-15 in a variety of molecules with SABRE-SHEATH (SABRE in Shield Enables Alignment Transfer to Heteronuclei). This strategy works in pure H2O or D2O solutions, on substrates that could not be hyperpolarized in traditional 1H-SABRE experiments, and we record 15N T1 relaxation times of up to 2 min.

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“…As a result of recently published results that showed a high pH dependence to SABRE efficiency, we also tested the effects of adding the salts, that is, NaCO 2 Me, NH 4 CO 2 Me, NH 4 Cl, NaOH, NaH(CO 3 ) and Na 2 CO 3 . These results are described in the Supporting Information and reveal that under spectroscopic examination, separate signals for pz can be seen in the two distinct phases in the majority of cases.…”

Section: Methodsmentioning

confidence: 99%

Achieving High Levels of NMR‐Hyperpolarization in Aqueous Media With Minimal Catalyst Contamination Using SABRE

Iali

Olaru

Green

et al. 2017

Chemistry A European J

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Signal amplification by reversible exchange (SABRE) is shown to allow access to strongly enhanced 1H NMR signals in a range of substrates in aqueous media. To achieve this outcome, phase‐transfer catalysis is exploited, which leads to less than 1.5×10−6 mol dm−3 of the iridium catalyst in the aqueous phase. These observations reflect a compelling route to produce a saline‐based hyperpolarized bolus in just a few seconds for subsequent in vivo MRI monitoring. The new process has been called catalyst separated hyperpolarization through signal amplification by reversible exchange or CASH‐SABRE. We illustrate this method for the substrates pyrazine, 5‐methylpyrimidine, 4,6‐d 2‐methyl nicotinate, 4,6‐d 2‐nicotinamide and pyridazine achieving 1H signal gains of approximately 790‐, 340‐, 3000‐, 260‐ and 380‐fold per proton at 9.4 T at the time point at which phase separation is complete.

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SABRE hyperpolarisation of vitamin B3 as a function of pH

Abstract: NMR sensitivity enhanced through SABRE hyperpolarisation and pH manipulation enables the use of vitamin B3 as a pH probe.

Cited by 49 publications

References 39 publications

Toward Hyperpolarized ¹⁹F Molecular Imaging via Reversible Exchange with Parahydrogen

Toward Hyperpolarized ¹⁹F Molecular Imaging via Reversible Exchange with Parahydrogen

Direct Hyperpolarization of Nitrogen-15 in Aqueous Media with Parahydrogen in Reversible Exchange

Achieving High Levels of NMR‐Hyperpolarization in Aqueous Media With Minimal Catalyst Contamination Using SABRE

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SABRE hyperpolarisation of vitamin B3 as a function of pH

Abstract: NMR sensitivity enhanced through SABRE hyperpolarisation and pH manipulation enables the use of vitamin B3 as a pH probe.

Cited by 49 publications

References 39 publications

Toward Hyperpolarized 19F Molecular Imaging via Reversible Exchange with Parahydrogen

Toward Hyperpolarized 19F Molecular Imaging via Reversible Exchange with Parahydrogen

Direct Hyperpolarization of Nitrogen-15 in Aqueous Media with Parahydrogen in Reversible Exchange

Achieving High Levels of NMR‐Hyperpolarization in Aqueous Media With Minimal Catalyst Contamination Using SABRE

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Toward Hyperpolarized ¹⁹F Molecular Imaging via Reversible Exchange with Parahydrogen

Toward Hyperpolarized ¹⁹F Molecular Imaging via Reversible Exchange with Parahydrogen