Para-hydrogen induced polarization of amino acids, peptides and deuterium–hydrogen gas

Glöggler, Stefan; Muller, Rafael J.; Colell, Johannes F. P.; Emondts, Meike; Dabrowski, Martin; Blümich, Bernhard; Appelt, Stephan

doi:10.1039/c1cp20992b

Cited by 116 publications

(120 citation statements)

References 30 publications

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“…Although in our experiments non-thermal polarization has been prepared by CIDNP our conclusions are valid for other kinds of hyperpolarization as well, most notably, for PHIP, in which case polarization transfer phenomena are common 13,[40][41][42][43] at low field. It is worth noting that although we studied only scalar coupled spins 1/2 our results are more general.…”

Section: Discussionmentioning

confidence: 52%

Exploiting level anti-crossings for efficient and selective transfer of hyperpolarization in coupled nuclear spin systems

Pravdivtsev

Yurkovskaya

Kaptein

et al. 2013

Phys. Chem. Chem. Phys.

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Spin hyperpolarization can be coherently transferred to other nuclei in field-cycling NMR experiments.At low magnetic fields spin polarization is redistributed in a strongly coupled network of spins.Polarization transfer is most efficient at fields where level anti-crossings (LACs) occur for the nuclear spin-states. A further condition is that field switching to the LAC positions is non-adiabatic in order to convert the starting population differences into spin coherences that cause time-dependent mixing of states. The power of this method has been demonstrated by studying transfer of photo-Chemically Induced Dynamic Nuclear Polarization (photo-CIDNP) in N-acetyl-tryptophan. We have investigated the magnetic field dependence and time dependence of coherent CIDNP transfer and directly assessed nuclear spin LACs by studying polarization transfer at specific field positions. The proposed approach based on LACs is not limited to CIDNP but is advantageous for enhancing NMR signals by spin order transfer from any type of hyper-polarized nuclei.

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Section: Discussionmentioning

confidence: 52%

Exploiting level anti-crossings for efficient and selective transfer of hyperpolarization in coupled nuclear spin systems

Pravdivtsev

Yurkovskaya

Kaptein

et al. 2013

Phys. Chem. Chem. Phys.

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“…With this approach, parahydrogen protons are not added to the substrate but the hyperpolarization transfer takes place on a transient adduct formed by the substrate, parahydrogen and the organometallic complex. This method has been successfully tested on several biologically relevant molecules such as pyrimidines, purines, amino acids and drugs 24,25 . However, in vivo application still suffers from low polarization levels and the need for suitable organometallic complex to efficiently renew hyperpolarization 26 .…”

mentioning

confidence: 99%

ParaHydrogen Induced Polarization of 13C carboxylate resonance in acetate and pyruvate

2015

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The advent of nuclear spins hyperpolarization techniques represents a breakthrough in the field of medical diagnoses by magnetic resonance imaging. Dynamic nuclear polarization (DNP) is the most widely used method, and hyperpolarized metabolites such as [1-13 C]-pyruvate are shown to report on status of tumours. Parahydrogen-induced polarization (PHIP) is a chemistry-based technique, easier to handle and much less expensive in respect to DNP, with significantly shorter polarization times. Its main limitation is the availability of unsaturated precursors for the target substrates; for instance, acetate and pyruvate cannot be obtained by direct incorporation of the parahydrogen molecule. Herein we report a method that allows us to achieve hyperpolarization in this kind of molecule by means of a tailored precursor containing a hydrogenable functionality that, after polarization transfer to the target 13 C moiety, is cleaved to obtain the metabolite of interest. The reported procedure can be extended to a number of other biologically relevant substrates.

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“…However, the only terms of the spin-coupling Hamiltonians that may be observed in high-field NMR are those that commute with the Zeeman Hamiltonian, which effectively truncates many interaction Hamiltonians that possess different symmetry. Recently, however, NMR experiments have been carried out in the opposite regime of very small magnetic fields [2][3][4][5], taking advantage of advances in hyperpolarization [6][7][8][9] and new detection modalities [10][11][12][13][14][15][16], which offer a significant time savings compared to earlier field-cycling techniques [17,18]. In zero-to ultra-low-field NMR (ZULF NMR), the strongest interactions are the local spin-spin couplings, which involve coupling tensors that are of different symmetry from the Zeeman Hamiltonian and are many orders of magnitude smaller in amplitude, thus permitting the direct observation of nuclear spin interactions that vanish at high magnetic fields.…”

mentioning

confidence: 99%

“…(8) and the higher-frequency peak corresponds to the ∆m F = ±1 transition described by Eq. (9). The magnitude and phase of the ∆m F = ±1 peak are determined by the projection of the initial spin-state population onto the transverse component of the detection operator, and is thus a signature of imperfections in the experimental configuration.…”

mentioning

confidence: 99%

Measurement of untruncated nuclear spin interactions via zero- to ultralow-field nuclear magnetic resonance

et al. 2015

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Zero-to ultra-low-field nuclear magnetic resonance (ZULF NMR) provides a new regime for the measurement of nuclear spin-spin interactions free from effects of large magnetic fields, such as truncation of terms that do not commute with the Zeeman Hamiltonian. One such interaction, the magnetic dipole-dipole coupling, is a valuable source of spatial information in NMR, though many terms are unobservable in high-field NMR, and the coupling averages to zero under isotropic molecular tumbling. Under partial alignment, this information is retained in the form of so-called residual dipolar couplings. We report zero-to ultra-low-field NMR measurements of residual dipolar couplings in acetonitrile-2-13 C aligned in stretched polyvinyl acetate gels. This represents the first investigation of dipolar couplings as a perturbation on the indirect spin-spin J-coupling in the absence of an applied magnetic field. As a consequence of working at zero magnetic field, we observe terms of the dipole-dipole coupling Hamiltonian that are invisible in conventional high-field NMR. This technique expands the capabilities of zero-to ultra-low-field NMR and has potential applications in precision measurement of subtle physical interactions, chemical analysis, and characterization of local mesoscale structure in materials.

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Para-hydrogen induced polarization of amino acids, peptides and deuterium–hydrogen gas

Cited by 116 publications

References 30 publications

Exploiting level anti-crossings for efficient and selective transfer of hyperpolarization in coupled nuclear spin systems

Exploiting level anti-crossings for efficient and selective transfer of hyperpolarization in coupled nuclear spin systems

ParaHydrogen Induced Polarization of 13C carboxylate resonance in acetate and pyruvate

Measurement of untruncated nuclear spin interactions via zero- to ultralow-field nuclear magnetic resonance

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