Read by QxMD icon Read

Signal amplification by reversible exchange

Soumya S Roy, Peter J Rayner, Philip Norcott, Gary G R Green, Simon B Duckett
The applicability of the magnetic resonance (MR) technique in the liquid phase is limited by poor sensitivity and short nuclear spin coherence times which are insufficient for many potential applications. Here we illustrate how it is possible to address both of these issues simultaneously by harnessing long-lived hyperpolarised spin states that are formed by adapting the Signal Amplification by Reversible Exchange (SABRE) technique. We achieve more than 4% net (1)H-polarisation in a long-lived form that remains detectable for over ninety seconds by reference to proton pairs in the biologically important molecule nicotinamide and a pyrazine derivative whose in vivo imaging will offer a new route to probe disease in the future...
September 14, 2016: Physical Chemistry Chemical Physics: PCCP
Eun Hae Oh, Seungwon Jung, Won Jin Kim, Kwang Pyo Kim, Sang Kyung Kim
The quantitative reverse transcription polymerase chain reaction (RT-qPCR) has become one of the most widely used methods in the detection of disease-specific RNAs. The RT-qPCR involves two separate steps, RT and qPCR. In this study, we suggest a new RT-qPCR protocol with the particles of primer-immobilized networks (PINs), performing capture, RT and amplification of a target RNA in one particle. The production of undesired cDNAs was dramatically suppressed by the specific capture of the target RNA within the particle...
August 18, 2016: Biosensors & Bioelectronics
Roman V Shchepin, Danila A Barskiy, Aaron M Coffey, Boyd M Goodson, Eduard Y Chekmenev
NMR hyperpolarization via Signal Amplification by Reversible Exchange (SABRE) was employed to investigate the feasibility of enhancing the NMR detection sensitivity of sulfur-heterocycles (specifically 2-methylthiophene and dibenzothiophenes), a family of compounds typically found in petroleum and refined petroleum products. SABRE hyperpolarization of sulfur-heterocycles (conducted in seconds) offers potential advantages of providing structural information about sulfur-containing contaminants in petroleum, thereby informing petroleum purification and refining to minimize sulfur content in refined products such as gasoline...
July 1, 2016: ChemistrySelect
Jean-Nicolas Dumez
This perspective article reviews some of the recent developments in the field of hyperpolarisation, with a focus on solution-state NMR spectroscopy of small molecules. Two techniques are considered in more detail, dissolution dynamic nuclear polarisation (D-DNP) and signal amplification by reversible exchange (SABRE). Some of the opportunities and challenges for applications of hyperpolarised solution-state magnetic resonance in chemistry are discussed.
August 6, 2016: Magnetic Resonance in Chemistry: MRC
Roman V Shchepin, Danila A Barskiy, Aaron M Coffey, Thomas Theis, Fan Shi, Warren S Warren, Boyd M Goodson, Eduard Y Chekmenev
(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 (pK a ∼ 7.0), and the binding event changes the (15)N isotropic chemical shift by ∼30 ppm...
June 24, 2016: ACS Sensors
Fan Shi, Ping He, Quinn A Best, Kirsten Groome, Milton L Truong, Aaron M Coffey, Greg Zimay, Roman V Shchepin, Kevin W Waddell, Eduard Y Chekmenev, Boyd M Goodson
Two synthetic strategies are investigated for the preparation of water-soluble iridium-based catalysts for NMR signal amplification by reversible exchange (SABRE). In one approach, PEGylation of a variant N-heterocyclic carbene provided a novel catalyst with excellent water solubility. However, while SABRE-active in ethanol solutions, the catalyst lost activity in >50% water. In a second approach, synthesis of a novel di-iridium complex precursor where the cyclooctadiene (COD) rings have been replaced by CODDA (1,2-dihydroxy-3,7-cyclooctadiene) leads to the creation of a catalyst [IrCl(CODDA)IMes] that can be dissolved and activated in water-enabling aqueous SABRE in a single step, without need for either an organic cosolvent or solvent removal followed by aqueous reconstitution...
June 9, 2016: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Danila A Barskiy, Roman V Shchepin, Aaron M Coffey, Thomas Theis, Warren S Warren, Boyd M Goodson, Eduard Y Chekmenev
Direct NMR hyperpolarization of naturally abundant (15)N sites in metronidazole is demonstrated using SABRE-SHEATH (Signal Amplification by Reversible Exchange in SHield Enables Alignment Transfer to Heteronuclei). In only a few tens of seconds, nuclear spin polarization P(15)N of up to ∼24% is achieved using parahydrogen with 80% para fraction corresponding to P(15)N ≈ 32% if ∼100% parahydrogen were employed (which would translate to a signal enhancement of ∼0.1-million-fold at 9.4 T). In addition to this demonstration on the directly binding (15)N site (using J(2)H-(15)N), we also hyperpolarized more distant (15)N sites in metronidazole using longer-range spin-spin couplings (J(4)H-(15)N and J(5)H-(15)N)...
July 6, 2016: Journal of the American Chemical Society
Peter Spannring, Indrek Reile, Meike Emondts, Philipp P M Schleker, Niels K J Hermkens, Nick G J van der Zwaluw, Bram J A van Weerdenburg, Paul Tinnemans, Marco Tessari, Bernhard Blümich, Floris P J T Rutjes, Martin C Feiters
NMR signal amplification by reversible exchange (SABRE) has been observed for pyridine, methyl nicotinate, N-methylnicotinamide, and nicotinamide in D2 O with the new catalyst [Ir(Cl)(IDEG)(COD)] (IDEG=1,3-bis(3,4,5-tris(diethyleneglycol)benzyl)imidazole-2-ylidene). During the activation and hyperpolarization steps, exclusively D2 O was used, resulting in the first fully biocompatible SABRE system. Hyperpolarized (1) H substrate signals were observed at 42.5 MHz upon pressurizing the solution with parahydrogen at close to the Earth's magnetic field, at concentrations yielding barely detectable thermal signals...
June 27, 2016: Chemistry: a European Journal
Alexandra M Olaru, Soumya S Roy, Lyrelle S Lloyd, Steven Coombes, Gary G R Green, Simon B Duckett
The creation of magnetic states that have long lifetimes has been the subject of intense investigation, in part because of their potential to survive the time taken to travel from the point of injection in a patient to the point where a clinically diagnostic MRI trace is collected. We show here that it is possible to harness the signal amplification by reversible exchange (SABRE) process to create such states in a hyperpolarised form that improves their detectability in seconds without the need for any chemical change by reference to the model substrate 2-aminothiazole...
June 14, 2016: Chemical Communications: Chem Comm
Philipp Rovedo, Stephan Knecht, Tim Bäumlisberger, Anna Lena Cremer, Simon B Duckett, Ryan E Mewis, Gary G R Green, Michael Burns, Peter J Rayner, Dieter Leibfritz, Jan G Korvink, Jürgen Hennig, Gerhard Pütz, Dominik von Elverfeldt, Jan-Bernd Hövener
In this work, we illustrate a method to continuously hyperpolarize a biomolecule, nicotinamide, in water using parahydrogen and signal amplification by reversible exchange (SABRE). Building on the preparation procedure described recently by Truong et al. [ J. Phys. Chem. B , 2014 , 118 , 13882 - 13889 ], aqueous solutions of nicotinamide and an Ir-IMes catalyst were prepared for low-field NMR and MRI. The (1)H-polarization was continuously renewed and monitored by NMR experiments at 5.9 mT for more than 1000 s...
June 30, 2016: Journal of Physical Chemistry. B
Angus W J Logan, Thomas Theis, Johannes F P Colell, Warren S Warren, Steven J Malcolmson
NMR with thermal polarization requires relatively concentrated samples, particularly for nuclei with low abundance and low gyromagnetic ratios, such as (15) N. We expand the substrate scope of SABRE, a recently introduced hyperpolarization method, to allow access to (15) N-enriched Schiff bases. These substrates show fractional (15) N polarization levels of up to 2 % while having only minimal (1) H enhancements.
July 25, 2016: Chemistry: a European Journal
Nan Eshuis, Ruud L E G Aspers, Bram J A van Weerdenburg, Martin C Feiters, Floris P J T Rutjes, Sybren S Wijmenga, Marco Tessari
SABRE (Signal Amplification By Reversible Exchange) nuclear spin hyperpolarization method can provide strongly enhanced NMR signals as a result of the reversible association of small molecules with para-hydrogen (p-H2) at an iridium metal complex. The conversion of p-H2 singlet order to enhanced substrate proton magnetization within such complex is driven by the scalar coupling interactions between the p-H2 derived hydrides and substrate nuclear spins. In the present study these long-range homonuclear couplings are experimentally determined for several SABRE substrates using an NMR pulse sequence for coherent hyperpolarization transfer at high magnetic field...
April 2016: Journal of Magnetic Resonance
Danila A Barskiy, Andrey N Pravdivtsev, Konstantin L Ivanov, Kirill V Kovtunov, Igor V Koptyug
We demonstrate an analytical model for the description of the signal amplification by reversible exchange (SABRE) process. The model relies on a combined analysis of chemical kinetics and the evolution of the nuclear spin system during the hyperpolarization process. The presented model for the first time provides rationale for deciding which system parameters (i.e. J-couplings, relaxation rates, reaction rate constants) have to be optimized in order to achieve higher signal enhancement for a substrate of interest in SABRE experiments...
January 7, 2016: Physical Chemistry Chemical Physics: PCCP
Andrey N Pravdivtsev, Konstantin L Ivanov, Alexandra V Yurkovskaya, Pavel A Petrov, Hans-Heinrich Limbach, Robert Kaptein, Hans-Martin Vieth
We have investigated the magnetic field dependence of Signal Amplification By Reversible Exchange (SABRE) arising from binding of para-hydrogen (p-H2) and a substrate to a suitable transition metal complex. The magnetic field dependence of the amplification of the (1)H Nuclear Magnetic Resonance (NMR) signals of the released substrates and dihydrogen, and the transient transition metal dihydride species shows characteristic patterns, which is explained using the theory presented here. The generation of SABRE is most efficient at low magnetic fields due to coherent spin mixing at nuclear spin Level Anti-Crossings (LACs) in the SABRE complexes...
December 2015: Journal of Magnetic Resonance
Nan Eshuis, Ruud L E G Aspers, Bram J A van Weerdenburg, Martin C Feiters, Floris P J T Rutjes, Sybren S Wijmenga, Marco Tessari
Nuclear magnetic resonance is often the technique of choice in chemical analysis because of its sensitivity to molecular structure, quantitative character, and straightforward sample preparation. However, determination of trace analytes in complex mixtures is generally limited by low sensitivity and extensive signal overlap. Here, we present an approach for continuous hyperpolarization at high magnetic field that is based on signal amplification by reversible exchange (SABRE) and can be straightforwardly incorporated in multidimensional NMR experiments...
November 23, 2015: Angewandte Chemie
Valeria Daniele, François-Xavier Legrand, Patrick Berthault, Jean-Nicolas Dumez, Gaspard Huber
Signal amplification by reversible exchange (SABRE) is a promising method to increase the sensitivity of nuclear magnetic resonance (NMR) experiments. However, SABRE-enhanced (1)H NMR signals are short lived, and SABRE is often used to record 1D NMR spectra only. When the sample of interest is a complex mixture, this results in severe overlaps for (1)H spectra. In addition, the use of a co-substrate, whose signals may obscure the (1) H spectra, is currently the most efficient way to lower the detection limit of SABRE experiments...
November 16, 2015: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Ryan E Mewis
To overcome the inherent sensitivity issue in NMR and MRI, hyperpolarisation techniques are used. Signal Amplification By Reversible Exchange (SABRE) is a hyperpolarisation technique that utilises parahydrogen, a molecule that possesses a nuclear singlet state, as the source of polarisation. A metal complex is required to break the singlet order of parahydrogen and, by doing so, facilitates polarisation transfer to analyte molecules ligated to the same complex through the J-coupled network that exists. The increased signal intensities that the analyte molecules possess as a result of this process have led to investigations whereby their potential as MRI contrast agents has been probed and to understand the fundamental processes underpinning the polarisation transfer mechanism...
October 2015: Magnetic Resonance in Chemistry: MRC
Bram J A van Weerdenburg, Nan Eshuis, Marco Tessari, Floris P J T Rutjes, Martin C Feiters
The new π-accepting ability parameter (PAAP) appears to be the best tool to analyse the electronic properties of NHC ligands in [Ir(H)2(NHC)(Py)3](+) complexes for SABRE. Together with the buried volume, the efficiency of hyperpolarisation transfer in SABRE, depending on the exchange rate of pyridine, can be described.
September 21, 2015: Dalton Transactions: An International Journal of Inorganic Chemistry
Tomasz Ratajczyk, Torsten Gutmann, Piotr Bernatowicz, Gerd Buntkowsky, Jaroslaw Frydel, Bartlomiej Fedorczyk
Signal amplification by reversible exchange (SABRE) can enhance nuclear magnetic resonance signals by several orders of magnitude. However, until now this was limited to a small number of model target molecules. Here, a new convenient method for SABRE activation applicable to a variety of synthetic model oligopeptides is demonstrated. For the first time, a highly SABRE-active pyridine-based biocompatible molecular framework is incorporated into synthetic oligopeptides. The SABRE activity is preserved, demonstrating the importance of such earmarking...
September 1, 2015: Chemistry: a European Journal
Bram J A van Weerdenburg, Anthonius H J Engwerda, Nan Eshuis, Alessandro Longo, Dipanjan Banerjee, Marco Tessari, Célia Fonseca Guerra, Floris P J T Rutjes, F Matthias Bickelhaupt, Martin C Feiters
Signal amplification by reversible exchange (SABRE) is an emerging hyperpolarization method in NMR spectroscopy, in which hyperpolarization is transferred through the scalar coupling network of para-hydrogen derived hydrides in a metal complex to a reversibly bound substrate. Substrates can even be hyperpolarized at concentrations below that of the metal complex by addition of a suitable co-substrate. Here we investigate the catalytic system used for trace detection in NMR spectroscopy with [Ir(IMes)(H)2 (L)3 ](+) (IMes=1,3-dimesitylimidazol-2-ylidene) as catalyst, pyridine as a substrate and 1-methyl-1,2,3-triazole as co-substrate in great detail...
July 13, 2015: Chemistry: a European Journal
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"