Author
Ruud L. E. G. Aspers
Other affiliations: Merck & Co.
Bio: Ruud L. E. G. Aspers is an academic researcher from Radboud University Nijmegen. The author has contributed to research in topics: Hyperpolarization (physics) & Chemistry. The author has an hindex of 11, co-authored 19 publications receiving 302 citations. Previous affiliations of Ruud L. E. G. Aspers include Merck & Co..
Papers
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TL;DR: 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 is presented.
Abstract: 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. This method was implemented in a 2D correlation experiment that allows detection and quantification of analytes at nanomolar concentration in complex solutions.
83 citations
TL;DR: 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.
50 citations
TL;DR: Surprisingly, certain junction conformations are aberrantly repaired to expansion mutations: misdirection of repair to the non-nicked strand opposite the slip-out leads to integration of the excess slipped-out repeats rather than their excision.
Abstract: Expansions of (CTG)·(CAG) repeated DNAs are the mutagenic cause of 14 neurological diseases, likely arising through the formation and processing of slipped-strand DNAs. These transient intermediates of repeat length mutations are formed by out-of-register mispairing of repeat units on complementary strands. The three-way slipped-DNA junction, at which the excess repeats slip out from the duplex, is a poorly understood feature common to these mutagenic intermediates. Here, we reveal that slipped junctions can assume a surprising number of interconverting conformations where the strand opposite the slip-out either is fully base paired or has one or two unpaired nucleotides. These unpaired nucleotides can also arise opposite either of the nonslipped junction arms. Junction conformation can affect binding by various structure-specific DNA repair proteins and can also alter correct nick-directed repair levels. Junctions that have the potential to contain unpaired nucleotides are repaired with a significantly h...
32 citations
TL;DR: An NMR approach based on parahydrogen hyperpolarization is presented to detect and resolve specific classes of metabolites in complex biomixtures at down to nanomolar concentrations.
32 citations
TL;DR: It is demonstrated that, despite a large decrease in attained hyperpolarization, this method can be extended to water–alcohol mixtures and was tested on whisky, where nitrogenous heterocyclic flavor components at low‐micromolar concentration could be detected and quantified.
Abstract: Nuclear magnetic resonance (NMR) studies of complex mixtures are often limited by the low sensitivity of the technique and by spectral overlap. We have recently reported on an NMR chemosensor on the basis of para-Hydrogen Induced Polarization that potentially addresses both these issues, albeit for specific classes of compounds. This approach makes use of Signal Amplification By Reversible Exchange (SABRE) catalysts in methanol and allows selective detection and quantification of dilute analytes in complex mixtures. Herein, we demonstrate that, despite a large decrease in attained hyperpolarization, this method can be extended to water-alcohol mixtures. Our approach was tested on whisky, where nitrogenous heterocyclic flavor components at low-micromolar concentration could be detected and quantified.
25 citations
Cited by
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TL;DR: The Handbook of Environmental Chemistry as discussed by the authors is a reference source for environmental scientists and decision-makers in industry, government, agencies and public-interest groups, providing sound and solid knowledge about environmental topics from a chemical perspective.
368 citations
University of Kiel1, Southern Illinois University Carbondale2, University of Florida3, Max Planck Society4, Novosibirsk State University5, Otto-von-Guericke University Magdeburg6, Hebrew University of Jerusalem7, New York University8, University of Turin9, Duke University10, Vanderbilt University11, Cedars-Sinai Medical Center12, University of Texas MD Anderson Cancer Center13, Wayne State University14, Russian Academy of Sciences15
TL;DR: Considerable progress has been made in the past decade in the area of pH2 -based hyperpolarization techniques for biomedical applications, covering the areas of spin physics, catalysis, instrumentation, preparation of the contrast agents, and applications.
Abstract: Magnetic resonance (MR) is one of the most versatile and useful physical effects used for human imaging, chemical analysis, and the elucidation of molecular structures. However, its full potential is rarely used, because only a small fraction of the nuclear spin ensemble is polarized, that is, aligned with the applied static magnetic field. Hyperpolarization methods seek other means to increase the polarization and thus the MR signal. A unique source of pure spin order is the entangled singlet spin state of dihydrogen, parahydrogen (pH2 ), which is inherently stable and long-lived. When brought into contact with another molecule, this "spin order on demand" allows the MR signal to be enhanced by several orders of magnitude. Considerable progress has been made in the past decade in the area of pH2 -based hyperpolarization techniques for biomedical applications. It is the goal of this Review to provide a selective overview of these developments, covering the areas of spin physics, catalysis, instrumentation, preparation of the contrast agents, and applications.
217 citations
TL;DR: In this article, the authors describe the emerging tendency for creating target-oriented analytical approaches designed to solve important chemical tasks by using a combination of analytical tools, illustrated by selected examples of advances of NMR spectroscopy, mass spectrometry and electron microscopy.
Abstract: In the present review we describe the emerging tendency for creating target-oriented analytical approaches designed to solve important chemical tasks by using a combination of analytical tools. The concept is illustrated by selected examples of advances of NMR spectroscopy, mass spectrometry and electron microscopy in the analysis and study of gas-phase, liquid-state and solid-state chemical systems. Comparative description of chemical applications of these analytical methods is presented and discussed. The bibliography includes 359 references.
192 citations
TL;DR: An increasing grasp of these factors holds prognostic and therapeutic potential, and naturally occurring polymorphic variants of DNA repair genes can have dramatic effects upon the levels of repeat instability, which may explain the variation in disease age-of-onset, progression and severity.
159 citations
TL;DR: This review will focus on mainly methodology improvements, particularly in pulse sequences, acquisition and processing methods which are particularly relevant to natural product research, with lesser discussion of hardware improvements.
151 citations