Category Archives: solid-state DNP

The effects of sample conductivity on the efficacy of dynamic nuclear polarization for sensitivity enhancement in solid state NMR spectroscopy #DNPNMR

Svirinovsky-Arbeli, Asya, Dina Rosenberg, Daniel Krotkov, Ran Damari, Krishnendu Kundu, Akiva Feintuch, Lothar Houben, Sharly Fleischer, and Michal Leskes. “The Effects of Sample Conductivity on the Efficacy of Dynamic Nuclear Polarization for Sensitivity Enhancement in Solid State NMR Spectroscopy.” Solid State Nuclear Magnetic Resonance 99 (July 2019): 7–14.

https://doi.org/10.1016/j.ssnmr.2019.02.003

In recent years dynamic nuclear polarization (DNP) has greatly expanded the range of materials systems that can be studied by solid state NMR spectroscopy. To date, the majority of systems studied by DNP were insulating materials including organic and inorganic solids. However, many technologically-relevant materials used in energy conversion and storage systems are electrically conductive to some extent or are employed as composites containing conductive additives. Such materials introduce challenges in their study by DNP-NMR which include microwave absorption and sample heating that were not thoroughly investigated so far.

DNP-enhanced NMR studies of cellular membrane disruption induced by Abeta40 peptides. #DNPNMR

DNP-enhanced NMR studies of cellular membrane disruption induced by Abeta40 peptides.

Supervisor: Dr Alexey Potapov

We are looking for a motivated PhD candidate interested in biophysical applications of magnetic resonance spectroscopy. This position is suitable for students with background in Physics, Chemistry or other related fields.

Aggregates of amyloid-beta peptides have been proposed to play role in causing Alzheimer\’s disease, however, their mechanism of action is not clearly understood. In this project, carried out in collaboration with SUNY Binghamton (USA), we focus on the process of cell membrane disruption by amyloid-beta and study its details using advanced nuclear magnetic resonance (NMR) techniques. One of such techniques is the dynamic nuclear polarization (DNP) allowing the NMR signals to be increased by a large factor. University of Nottingham is hosting a modern DNP-enhanced solid-state NMR Facility (unique in the UK) funded by a grant of £2.5 M from EPSRC.

The PhD studentship is available immediately, and is fully funded for 3.5 years via a stipend covering PhD tuition fees (at the UK/EU rate) and a tax-free living allowance.

The Sir Peter Mansfield Imaging Centre, which is part of the School of Physics and Astronomy of the University of Nottingham, is well equipped and conducts a very active research program in many aspects of modern magnetic resonance (http://www.nottingham.ac.uk/magres/index.aspx). For more details please contact Dr Alexey Potapov (alexey.potapov@nottingham.ac.uk)

Dr Alexey Potapov

Assistant Professor in Magnetic Resonance

Sir Peter Mansfield Imaging Center

School of Physics and Astronomy

University of Nottingham

Nottingham NG7 2RD United Kingdom

p: (44) 115 951 4739

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PhD position in biomolecular solid-state NMR – Groningen, Netherlands

PhD position in Structural biology of Huntington’s disease using solid-state NMR

University of Groningen, Zernike Institute for Advanced Materials (Netherlands)

Van der Wel Solid-state NMR Group

We are looking to fill a PhD position for an exciting new project in our lab at the University of Groningen. This project is funded by a grant from the Netherlands’ Campagneteam Huntington – a community-driven effort to fund Huntington’s disease (HD) research in the Netherlands.

The researcher will use solid-state NMR and electron microscopy for molecular studies of the central protein misfolding event behind the neurodegenerative disease HD. Tailor-made solid-state NMR experiments will be used to provide an atomic view of the protein aggregates. For an integrated structure/toxic-function analysis, the project will include toxicity assays in human neuronal cells and aggregation modulation studies. The PhD researcher will perform the cellular assays with the group of Prof. Amalia Dolga, our close collaborator in the Groningen Research Institute of Pharmacy. The interdisciplinary studies are designed to yield a new understanding of this devastating disease, with likely implications for other neurodegenerative disorders associated with protein aggregation.

Recent HD research papers from the lab:

• Hoop et al. (2016) Huntingtin exon 1 fibrils feature an interdigitated β-hairpin–based polyglutamine core. PNAS 113(6):1546–51.

• Lin et al. (2017) Fibril polymorphism affects immobilized non-amyloid flanking domains of huntingtin exon1 rather than its polyglutamine core. Nat Commun. 8:15462.

• Smith et al. (2018) Structural fingerprinting of protein aggregates by dynamic nuclear polarization-enhanced solid-state NMR at natural isotopic abundance. J Am Chem Soc 140(44): 14576-14580.

The candidate is expected to have a Master’s degree (or potentially a BSc degree with demonstrable research experience*) in bio- or physical chemistry, (bio)physics or another field of science relevant for the position. Experience with NMR, and especially solid-state NMR, is an important consideration, but may not be essential (depending on the background of the candidate). Applicants with a background and interest in protein biophysics or protein aggregation are encouraged to apply.

For information or questions about the project, application procedure, and requirements, potential applicants should contact Dr Van der Wel at p.c.a.van.der.wel@rug.nl

Additional background information about the lab is also available on our website https://www.vanderwellab.org/

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Maximizing nuclear hyperpolarization in pulse cooling under MAS #DNPNMR

Björgvinsdóttir, Snædís, Brennan J. Walder, Nicolas Matthey, and Lyndon Emsley. “Maximizing Nuclear Hyperpolarization in Pulse Cooling under MAS.” Journal of Magnetic Resonance 300 (March 1, 2019): 142–48.

https://doi.org/10.1016/j.jmr.2019.01.011.

It has recently been shown how dynamic nuclear polarization can be used to hyperpolarize the bulk of proton-free solids. This is achieved by generating the polarization in a wetting phase, transferring it to nuclei near the surface and relaying it towards the bulk through homonuclear spin diffusion between weakly magnetic nuclei. Pulse cooling is a strategy to achieve this that uses a multiple contact cross-polarization sequence for bulk hyperpolarization. Here, we show how to maximize sensitivity using the pulse cooling method by experimentally optimizing pulse parameters and delays on a sample of powdered SnO2. To maximize sensitivity we introduce an approach where the magic angle spinning rate is modulated during the experiment: the CP contacts are carried out at a slow spin rate to benefit from faster spin diffusion, and the spin rate is then accelerated before detection to improve line narrowing. This method can improve the sensitivity of pulse cooling for 119Sn spectra of SnO2 by an additional factor of 3.5.

Hyperpolarized MAS NMR of unfolded and misfolded proteins #DNPNMR

König, Anna, Daniel Schölzel, Boran Uluca, Thibault Viennet, Ümit Akbey, and Henrike Heise. “Hyperpolarized MAS NMR of Unfolded and Misfolded Proteins.” Solid State Nuclear Magnetic Resonance 98 (April 2019): 1–11.

https://doi.org/10.1016/j.ssnmr.2018.12.003

In this article we give an overview over the use of DNP-enhanced solid-state NMR spectroscopy for the investigation of unfolded, disordered and misfolded proteins. We first provide an overview over studies in which DNP spectroscopy has successfully been applied for the structural investigation of well-folded amyloid fibrils formed by short peptides as well as full-length proteins. Sample cooling to cryogenic temperatures often leads to severe linebroadening of resonance signals and thus a loss in resolution. However, inhomogeneous linebroadening at low temperatures provides valuable information about residual dynamics and flexibility in proteins, and, in combination with appropriate selective isotope labeling techniques, inhomogeneous line-widths in disordered proteins or protein regions may be exploited for evaluation of conformational ensembles. In the last paragraph we highlight some recent studies where DNP-enhanced MAS-NMR-spectroscopy was applied to the study of disordered proteins/protein regions and inhomogeneous sample preparations.

Amplification of Dynamic Nuclear Polarization at 200 GHz by Arbitrary Pulse Shaping of the Electron Spin Saturation Profile #DNPNMR

Kaminker, Ilia, and Songi Han. “Amplification of Dynamic Nuclear Polarization at 200 GHz by Arbitrary Pulse Shaping of the Electron Spin Saturation Profile.” The Journal of Physical Chemistry Letters 9, no. 11 (June 7, 2018): 3110–15.

https://doi.org/10.1021/acs.jpclett.8b01413

Dynamic nuclear polarization (DNP) takes center stage in nuclear magnetic resonance (NMR) as a tool to amplify its signal by orders of magnitude through the transfer of polarization from electron to nuclear spins. In contrast to modern NMR and electron paramagnetic resonance (EPR) that extensively rely on pulses for spin manipulation in the time domain, the current mainstream DNP technology exclusively relies on monochromatic continuous wave (CW) irradiation. This study introduces arbitrary phase shaped pulses that constitute a train of coherent chirp pulses in the time domain at 200 GHz (7 T) to dramatically enhance the saturation bandwidth and DNP performance compared to CW DNP, yielding up to 500-fold in NMR signal enhancements. The observed improvement is attributed to the recruitment of additional electron spins contributing to DNP via the cross-effect mechanism, as experimentally confirmed by two-frequency pump–probe electron–electron double resonance (ELDOR).

Direct (17)O dynamic nuclear polarization of single-site heterogeneous catalysts #DNPNMR

Perras, F. A., K. C. Boteju, Slowing, A. D. Sadow, and M. Pruski. “Direct (17)O Dynamic Nuclear Polarization of Single-Site Heterogeneous Catalysts.” Chem Commun (Camb) 54 (April 3, 2018): 3472–75.

https://doi.org/10.1039/C8CC00293B

We utilize direct 17O DNP for the characterization of non-protonated oxygens in heterogeneous catalysts. The optimal sample preparation and population transfer approach for 17O direct DNP experiments performed on silica surfaces is determined and applied to the characterization of Zr- and Y-based mesoporous silica-supported single-site catalysts.

Unusual Local Molecular Motions in the Solid State Detected by Dynamic Nuclear Polarization Enhanced NMR Spectroscopy #DNPNMR

Hoffmann et al., “Unusual Local Molecular Motions in the Solid State Detected by Dynamic Nuclear Polarization Enhanced NMR Spectroscopy.”

https://doi.org/10.1021/acs.jpcc.7b07965

Polyethylene glycol (PEG) and three related surfactants were studied by dynamic nuclear polarization (DNP) enhanced solid state NMR spectroscopy and differential scanning calorimetry (DSC). DNP enhanced solid state NMR surprisingly reveals the presence of local molecular motions that are normally understood to be inactive at temperatures ∼100 K. This surprising phenomenon could be explained by the experimentally necessary rapid freezing of the studied samples. Specifically, DSC shows that PEG 200 forms a glass upon freezing and that the three PEG-related surfactants are at least partially in a glass state or some other thermodynamic nonequilibrium state when rapidly frozen to the temperatures of the DNP enhanced solid state NMR experiments. This effect of preserving local molar motions by rapid freezing also holds true for solutions of organic solutes in the PEG 200 solvent matrix.

Dynamic Nuclear Polarization Signal Amplification as a Sensitive Probe for Specific Functionalization of Complex Paper Substrates #DNPNMR

Gutmann et al., “Dynamic Nuclear Polarization Signal Amplification as a Sensitive Probe for Specific Functionalization of Complex Paper Substrates.”

https://pubs.acs.org/doi/abs/10.1021/acs.jpcc.6b11751

In this work, it is shown how solid-state NMR combined with dynamic nuclear polarization (DNP) can be employed as a powerful tool to selectively enhance the spectral intensity of functional groups on the surface of cellulose fibers in paper materials. As a model system, a poly(benzyl methacrylate) (PBEMA)-functionalized paper material is chosen that contains hydrophobic and hydrophilic domains. Detailed analysis of the DNP NMR data and of T1ρ data suggests that inhomogeneous 1H–1H spin diffusion is responsible for the observed differences in signal enhancement. These findings are fundamental for structural understanding of complex paper substrates for fluid transport or sensor materials.

[NMR] PhD and Postdoctoral positions available to join the Emsley group at EPFL #DNPNMR

PhD and Postdoctoral positions available to join the Emsley group at EPFL, Lausanne


We are looking for highly motivated candidates to take up PhD and Postdoctoral positions developing new methods in NMR spectroscopy to address challenging problems in chemistry and materials science. In particular we will be working on extending dynamic nuclear polarization enhanced NMR crystallography to complex non-crystalline materials. Examples of our recent work and the application areas that we work on can be found on our website: http://lrm.epfl.ch


We are looking for highly motivated candidates with strong scientific background, independence, and who enjoy teamwork. You should hold a relevant qualification in chemistry, physics or related disciplines. Skills in one of the following fields of expertise are a plus:


• Experimental multi-dimensional nuclear magnetic resonance,
• 
Simulation, Theory, or Modelling of nuclear spin dynamics, NMR properties or chemical structures.
 

Our laboratory at EPFL is part of one the world’s leading chemistry departments, and is located Lausanne on the north shore of Lake Geneva. The laboratory is equipped with unique state of the art NMR spectrometers (including gyrotron DNP accessories at 400 and 900 MHz, a dissolution-DNP machine, and 100 kHz magic angle spinning probes).

 
Motivated candidates should contact Lyndon Emsley by email to lyndon.emsley@epfl.ch


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