Detection of Picomole Amounts of Biological Substrates by <i>para</i>-Hydrogen-Enhanced NMR Methods in Conjunction with a Suitable Receptor Complex

Wood, Nicholas; Brannigan, J.A.; Duckett, Simon B.; Heath, Sarah L.; Wagstaff, Jane

doi:10.1021/ja074286k

Cited by 41 publications

(49 citation statements)

References 11 publications

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“…Here, we have devised an NMR-based chemosensor that reveals analyte association to the receptor by NMR signals in the hydride region of the 1 H spectrum, generally free from background contributions. 23 For each species associating to the iridium center, the chemosensor response consists of a pair of hyperpolarized hydride lines ("A" and "X" in complex (1)) in the NMR spectrum. Thanks to the p-H 2 derived hydride signal enhancement (up to 1000-fold increase compared to NMR at thermal equilibrium), it is possible to lower the detection limits of this NMR chemosensor to submicromolar concentrations.…”

Section: ■ Resultsmentioning

confidence: 99%

“…Importantly, this association can be exploited to generate highly enhanced NMR signals via parahydrogen (p-H 2 ) induced hyperpolarization. 23,24 Therefore, our approach allows at once to overcome NMR sensitivity limitations and to detect the analytes of interest, while removing the large background originating from the complex matrix. We have applied our NMR chemosensing experiment to quantitatively determine specific classes of flavor components in a methanol extract of roasted ground coffee.…”

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confidence: 99%

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NMR-Based Chemosensing via p-H₂ Hyperpolarization: Application to Natural Extracts

Hermkens¹,

Eshuis²,

Weerdenburg³

et al. 2016

Anal. Chem.

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When dealing with trace analysis of complex mixtures, NMR suffers from both low sensitivity and signal overlap. NMR chemosensing, in which the association between an analyte and a receptor is "signaled" by an NMR response, has been proposed as a valuable analytical tool for biofluids and natural extracts. Such chemosensors offer the possibility to simultaneously detect and distinguish different analytes in solution, which makes them particularly suitable for analytical applications on complex mixtures. In this study, we have combined NMR chemosensing with nuclear spin hyperpolarization. This was realized using an iridium complex as a receptor in the presence of parahydrogen: association of the target analytes to the metal center results in approximately 1000-fold enhancement of the NMR response. This amplification allows the detection, identification, and quantification of analytes at low-micromolar concentrations, provided they can weakly associate to the iridium chemosensor. Here, our NMR chemosensing approach was applied to the quantitative determination of several flavor components in methanol extracts of ground coffee.

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Section: ■ Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

NMR-Based Chemosensing via p-H₂ Hyperpolarization: Application to Natural Extracts

Hermkens¹,

Eshuis²,

Weerdenburg³

et al. 2016

Anal. Chem.

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“…The significance of the trans effect is also illustrated by the set of rhodoximes containing axial py and various auxiliary ligands X, described by Rentsch et 2 ] formula (P * = triphenylphosphine, P(C 6 H 5 ) 3 ; tribenzylphosphine, P(CH 2 C 6 H 5 ) 3 ; tricyclohexylphosphine, P(C 6 H 11 ) 3 ), for which the | 15N coord | parameters are ca 48-56 ppm [26] ; in case of another trans (H,N) [33,34] (Table 6 2 Cl 2 ] + , the | 15N coord | parameters vary within ca 106-120 ppm range. [34] The differences between their values for nitrogens trans to N (ca 111-117 ppm for both cis-[Ir(LL) 2 2 Cl 2 ] + ) [34] are ca 20-30 ppm larger than in case of their Rh(III) analogs.…”

Section: Octahedral Co(iii) Complexes (D 6 )mentioning

confidence: 99%

15N NMR coordination shifts in Pd(II), Pt(II), Au(III), Co(III), Rh(III), Ir(III), Pd(IV), and Pt(IV) complexes with pyridine, 2,2′-bipyridine, 1,10-phenanthroline, quinoline, isoquinoline, 2,2′-biquinoline, 2,2′:6′, 2′-terpyridine and their alkyl or aryl

Pazderski

2008

Magn. Reson. Chem.

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The 15N NMR data for 105 complexes of Pd(II), Pt(II), Au(III), Co(III), Rh(III), Ir(III), Pd(IV), and Pt(IV) complexes with simple azines such as pyridine, 2,2'-bipyridine, 1,10-phenanthroline, quinoline, isoquinoline, 2,2'-biquinoline, 2,2':6', 2''-terpyridine and their alkyl or aryl derivatives have been reviewed. The 15N NMR coordination shifts, i.e. the differences between the 15N chemical shifts of the same nitrogen in the molecules of the complex and the ligand (Delta(15N) (coord) = delta(15N) (compl)--delta(15N) (lig)), have been related to some structural features of the reviewed coordination compounds, like the type of the central ion and the character of auxiliary ligands (mainly in trans position). These Delta(15N) (coord) parameters are negative, their absolute magnitudes (ca 30-150 ppm) generally increasing in the metal order Au(III) < Pd(II) < Pt(II) and Rh(III) < Co(III) < Pt(IV) < Ir(III), as well as with the enhanced trans influence of the other donor atoms (H, C << Cl < N).

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“…Specifically, a variety of applications ranging from MRI contrast agents [7,23,59,[67][68][69][70]86,87] to metabolomic studies [155,158] are performed by transferring the large 1 H polarization to longer lived heteronuclei like 13 C. There has also been interest in using p−H 2 to generate entangled quantum states of very high purity for studies in quantum information processing [10,11,28]. This active interest in p − H 2 polarization has also prompted a number of theoretical studies investigating the mechanism of ortho and para interconversion in a variety of chemically relevant conditions [8,13,110,151].…”

Section: Applicationsmentioning

confidence: 99%

MRI of Heterogeneous Hydrogenation Reactions Using Parahydrogen Polarization

Burt

2008

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The power of magnetic resonance imaging (MRI) is its ability to image the internal structure of optically opaque samples and provide detailed maps of a variety of important parameters, such as density, diffusion, velocity and temperature. However, one of the fundamental limitations of this technique is its inherent low sensitivity. For example, the low signal to noise ratio (SNR) is particularly problematic for imaging gases in porous materials due to the low density of the gas and the large volume occluded by the porous material. This is unfortunate, as many industrially relevant chemical reactions take place at gas-surface interfaces in porous media, such as packed catalyst beds. Because of this severe SNR problem, many techniques have been developed to directly increase the signal strength. These techniques work by manipulating the nuclear spin populations to produce polarized (i.e. non-equilibrium) states with resulting signal strengths that are orders of magnitude larger than those available at thermal equilibrium. 2This dissertation is concerned with an extension of a polarization technique based on the properties of parahydrogen. Specifically, I report on the novel use of heterogeneous catalysis to produce parahydrogen induced polarization and applications of this new technique to gas phase MRI and the characterization of micro-reactors. First, I provide an overview of nuclear magnetic resonance (NMR) and how parahydrogen is used to improve the SNR of the NMR signal. I then present experimental results demonstrating that it is possible to use heterogeneous catalysis to produce parahydrogen-induced polarization.These results are extended to imaging void spaces using a parahydrogen polarized gas. In the second half of this dissertation, I demonstrate the use of parahydrogen-polarized gasphase MRI for characterizing catalytic microreactors. Specifically, I show how the improved SNR allows one to map parameters important for characterizing the heat and mass transport in a heterogeneous catalyst bed. This is followed by appendices containing detailed

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Detection of Picomole Amounts of Biological Substrates by para-Hydrogen-Enhanced NMR Methods in Conjunction with a Suitable Receptor Complex

Cited by 41 publications

References 11 publications

NMR-Based Chemosensing via p-H₂ Hyperpolarization: Application to Natural Extracts

NMR-Based Chemosensing via p-H₂ Hyperpolarization: Application to Natural Extracts

15N NMR coordination shifts in Pd(II), Pt(II), Au(III), Co(III), Rh(III), Ir(III), Pd(IV), and Pt(IV) complexes with pyridine, 2,2′-bipyridine, 1,10-phenanthroline, quinoline, isoquinoline, 2,2′-biquinoline, 2,2′:6′, 2′-terpyridine and their alkyl or aryl

MRI of Heterogeneous Hydrogenation Reactions Using Parahydrogen Polarization

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Detection of Picomole Amounts of Biological Substrates by para-Hydrogen-Enhanced NMR Methods in Conjunction with a Suitable Receptor Complex

Cited by 41 publications

References 11 publications

NMR-Based Chemosensing via p-H2 Hyperpolarization: Application to Natural Extracts

NMR-Based Chemosensing via p-H2 Hyperpolarization: Application to Natural Extracts

15N NMR coordination shifts in Pd(II), Pt(II), Au(III), Co(III), Rh(III), Ir(III), Pd(IV), and Pt(IV) complexes with pyridine, 2,2′-bipyridine, 1,10-phenanthroline, quinoline, isoquinoline, 2,2′-biquinoline, 2,2′:6′, 2′-terpyridine and their alkyl or aryl

MRI of Heterogeneous Hydrogenation Reactions Using Parahydrogen Polarization

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NMR-Based Chemosensing via p-H₂ Hyperpolarization: Application to Natural Extracts

NMR-Based Chemosensing via p-H₂ Hyperpolarization: Application to Natural Extracts