DNP-NMR Literature Blog

Zero-field nuclear magnetic resonance of chemically exchanging systems

Barskiy, Danila A., Michael C. D. Tayler, Irene Marco-Rius, John Kurhanewicz, Daniel B. Vigneron, Sevil Cikrikci, Ayca Aydogdu, et al. “Zero-Field Nuclear Magnetic Resonance of Chemically Exchanging Systems.” Nature Communications 10, no. 1 (December 2019): 3002.

https://doi.org/10.1038/s41467-019-10787-9.

Zero- to ultralow-field (ZULF) nuclear magnetic resonance (NMR) is an emerging tool for precision chemical analysis. In this work, we study dynamic processes and investigate the influence of chemical exchange on ZULF NMR J-spectra. We develop a computational approach that allows quantitative calculation of J-spectra in the presence of chemical exchange and apply it to study aqueous solutions of [15N]ammonium (15NHfl4 ) as a model system. We show that pH-dependent chemical exchange substantially affects the J-spectra and, in some cases, can lead to degradation and complete disappearance of the spectral features. To demonstrate potential applications of ZULF NMR for chemistry and biomedicine, we show a ZULF NMR spectrum of [2-13C]pyruvic acid hyperpolarized via dissolution dynamic nuclear polarization (dDNP). We foresee applications of affordable and scalable ZULF NMR coupled with hyperpolarization to study chemical exchange phenomena in vivo and in situations where high-field NMR detection is not possible to implement.

Hyperpolarized relaxometry based nuclear T1 noise spectroscopy in diamond

Ajoy, A., B. Safvati, R. Nazaryan, J. T. Oon, B. Han, P. Raghavan, R. Nirodi, et al. “Hyperpolarized Relaxometry Based Nuclear T1 Noise Spectroscopy in Diamond.” Nature Communications 10, no. 1 (December 2019): 5160.

https://doi.org/10.1038/s41467-019-13042-3.

The origins of spin lifetimes in quantum systems is a matter of importance in several areas of quantum information. Spectrally mapping spin relaxation processes provides insight into their origin and motivates methods to mitigate them. In this paper, we map nuclear relaxation in a prototypical system of 13C nuclei in diamond coupled to Nitrogen Vacancy (NV) centers over a wide field range (1 mT-7 T). Nuclear hyperpolarization through optically pumped NV electrons allows signal measurement savings exceeding million-fold over conventional methods. Through a systematic study with varying substitutional electron (P1 center) and 13C concentrations, we identify the operational relaxation channels for the nuclei at different fields as well as the dominant role played by 13C coupling to the interacting P1 electronic spin bath. These results motivate quantum control techniques for dissipation engineering to boost spin lifetimes in diamond, with applications including engineered quantum memories and hyperpolarized 13C imaging.

[NMR] Postdoc position → Hyperpolarization at the CRMN in Lyon #DNPNMR

Generating and Transporting Hyperpolarization for preclinical MRI

A Postdoctoral position is available working in the group of Prof. Sami Jannin HMRLab on a project funded by the European Research Council, at CRMN in the city of Lyon, France.
We are looking for highly motivated candidate with strong scientific background, independence, and who enjoy teamwork. For postdoctoral positions, you must hold a PhD in Chemistry, Physics or related disciplines. Skills in will be appreciated in Nuclear magnetic resonance and possibly Dynamic nuclear polarization.

The candidate will in particular:

o   Perform low temperature DNP experiments with a functional state-of-the-art Bruker prototype polarizer, using novel hyperpolarizing materials that are synthetized in our team and that extend the lifetime of hyperpolarized MRI tracers to days (see doi:10.1038/ncomms13975doi:10.1073/pnas.1407730111, poster  here, and videos here )o   Transport hyperpolarized molecules to the preclinical MRI facility agro-resonance with a newly developed hyperpolarization transport system, and participate together with the specialized MRI team of Jean-Marie Bonny to pre-clinical imaging experiments.

The position will be open until filled with a possible starting date January-March 2021 with a one-year time commitment required and a possibility for two-years extension. 

You can get directly in touch directly with sami.jannin@univ-lyon1.fr for further details on the position, and submit your application via e-mail as a single PDF file including:
i)              a cover letter (explaining background and motivation),
ii)             your CV,
iii)            contact information of 2-3 references.

The Center for Very High Field NMR is one of the world’s leading magnetic resonance laboratories, located in the great city of Lyon, which is affiliated to the Lyon-1 University, the CNRS (French National Center for Scientific Research) and the Ecole Normale Supérieure de Lyon. The center is equipped with state-of-the-art NMR spectrometers (500 – 700 – 800 MHz, and the world’s first 1 GHz spectrometer) with two state of the art dissolution-DNP machines. It hosts research groups of worldwide-recognized excellence.

 Sami Jannin 
Professor at the Lyon 1 University 
  
Deputy Director Centre de RMN à Très Hauts Champs http://crmn-lyon.fr 
5 rue de la Doua 
69100 Villeurbanne FRANCE 
  
Team Leader Hyperpolarized Magnetic Resonance Lab http://hmrlab.eu 
  
Head of Lyon 1 University ERC support program 
  
mobile: +33 6 67 90 77 52 
office: +33 4 37 42 35 27
 We are hosting HYP21 
the 6th Hyperpolarization Conference 
in Lyon
http://hyp20.org 
 
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Photochemically induced dynamic nuclear polarization NMR on photosystem II: donor cofactor observed in entire plant #CIDNP

Janssen, Geertje J., Pavlo Bielytskyi, Denis G. Artiukhin, Johannes Neugebauer, Huub J. M. de Groot, Jörg Matysik, and A. Alia. “Photochemically Induced Dynamic Nuclear Polarization NMR on Photosystem II: Donor Cofactor Observed in Entire Plant.” Scientific Reports 8, no. 1 (December 2018): 17853.

https://doi.org/10.1038/s41598-018-36074-z.

The solid-state photo-CIDNP (photochemically induced dynamic nuclear polarization) effect allows for increase of signal and sensitivity in magic-angle spinning (MAS) NMR experiments. The effect occurs in photosynthetic reaction centers (RC) proteins upon illumination and induction of cyclic electron transfer. Here we show that the strength of the effect allows for observation of the cofactors forming the spin-correlated radical pair (SCRP) in isolated proteins, in natural photosynthetic membranes as well as in entire plants. To this end, we measured entire selectively 13C isotope enriched duckweed plants (Spirodela oligorrhiza) directly in the MAS rotor. Comparison of 13C photo-CIDNP MAS NMR spectra of photosystem II (PS2) obtained from different levels of RC isolation, from entire plant to isolated RC complex, demonstrates the intactness of the photochemical machinery upon isolation. The SCRP in PS2 is structurally and functionally very similar in duckweed and spinach (Spinacia oleracea). The analysis of the photo-CIDNP MAS NMR spectra reveals a monomeric Chl a donor. There is an experimental evidence for matrix involvement, most likely due to the axial donor histidine, in the formation of the SCRP. Data do not suggest a chemical modification of C-131 carbonyl position of the donor cofactor.

Post-Doctoral Position Opening – Sherwin Group: High-power arbitrary waveform generation for pulsed magnetic resonance at 240 GHz and above, with applications dependent on post-doc’s interest.

Find the complete job description here:
https://recruit.ap.ucsb.edu/JPF01895

Background: Coherent manipulation of electron spins at magnetic fields above 7 T (frequencies above 200 GHz) is required for investigations of decoherence in potential quantum bits, excitations of strongly-correlated spin systems, spintronics, and the structure and dynamics of biological macromolecules. However, with current technology, it is exceedingly difficult to generate the sequences of high-power sub-THz pulses that are required for these studies. By “slicing” a sequence of pulses from the ~kW output of UCSB’s MM-wave Free-Electron Laser, we have made significant progress towards filling this technological gap, and have demonstrated the world’s first FEL-powered electron paramagnetic resonance (EPR) spectrometer at 240 GHz. The existing “pulse slicer” uses high-power doubled Nd:YAG lasers to drive Si wafers from the insulating (transmissive) state to the conducting (reflective) state. It occupies two optical tables and is not easily reproduced.

The project: In collaboration with Bridge12, a small company in the Boston area, we have recently been funded to develop a “compact pulse slicer for high-power sub-millimeter waves.” The goal is to leverage advances in inexpensive solid-state laser and semiconductor wafer-bonding technologies to demonstrate a pulse slicer that can eventually be commercialized and deployed for use with existing submillimeter wave sources called gyrotrons to enable pulsed EPR and pulsed dynamic nuclear polarization. The team includes highly-experienced Ph. D. level scientists at UCSB, Bridge12, in the ThorLabs Crystalline Mirror Coatings division.

The job: The successful post-doc will, in close collaboration with the team, develop the optics and electronics for both reflective and transmissive elements of the compact pulse slicer, model the carrier dynamics in the semiconductor switches, perform pulse slicing experiments, and compare performance with theoretical predictions. With the pulse slicer they develop, the post-doc will be encouraged to pursue a scientific direction they are interested in within the broad range of topics under investigation in the Sherwin group. After completion of the post-doctoral job, the post-doc will be well positioned for a wide range of career options, including in academia, industry, and government labs.

Requirements: Applicants must have a Ph. D. in Physics, Applied Physics, Materials, Electrical Engineering, Physical Chemistry, or a related field of science or engineering at the time of application. Experience with developing scientific instrumentation, numerical modeling of physical phenomena, and one or more of the methodologies used in this project (for example, optics, lasers, semiconductors, microwaves, magnetic resonance) is preferred.

Magnets for Small-Scale and Portable NMR

Blümich, Bernhard, Christian Rehorn, and Wasif Zia. “Magnets for Small-Scale and Portable NMR.” In Micro and Nano Scale NMR, by Jens Anders and Jan G. Korvink, 1–20. Advanced Micro and Nanosystems. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2018.

https://doi.org/10.1002/9783527697281.ch1.

Nuclear magnetic resonance (NMR) exploits the resonance of the precessing motion of nuclear magnetization in magnetic fields. From the measurement methodology, three groups of common techniques of probing resonance can be assigned: those employing forced oscillations, free oscillations, and interferometric principles. In either case, the sensitivity depends on the strength of the nuclear magnetic polarization, which, in thermodynamic equilibrium at temperatures higher than few degrees above absolute zero, is in good approximation proportional to the strength of the magnetic field. In recognition of this fact, one guideline in the development of NMR magnets has always been to reach high field strength.The highest field strength of temporally stable magnetic fields today is achieved with superconducting electromagnets. This is why most standard NMR instruments used for NMR spectroscopy in chemical analysis and magnetic resonance imaging (MRI) in medical diagnostics employ superconducting magnets cooled to the low temperature of boiling helium with cryogenic technology.

Small Molecules, Non-Covalent Interactions, and Confinement #DNPNMR

Buntkowsky, Gerd, and Michael Vogel. “Small Molecules, Non-Covalent Interactions, and Confinement.” Molecules 25, no. 14 (July 21, 2020): 3311.

https://doi.org/10.3390/molecules25143311

This review gives an overview of current trends in the investigation of small guest molecules, confined in neat and functionalized mesoporous silica materials by a combination of solid-state NMR and relaxometry with other physico-chemical techniques. The reported guest molecules are water, small alcohols, and carbonic acids, small aromatic and heteroaromatic molecules, ionic liquids, and surfactants. They are taken as characteristic role-models, which are representatives for the typical classes of organic molecules. It is shown that this combination delivers unique insights into the structure, arrangement, dynamics, guest-host interactions, and the binding sites in these confined systems, and is probably the most powerful analytical technique to probe these systems.

Shedding light on the atomic-scale structure of amorphous silica–alumina and its Brønsted acid sites #DNPNMR

Perras, Frédéric A., Zichun Wang, Takeshi Kobayashi, Alfons Baiker, Jun Huang, and Marek Pruski. “Shedding Light on the Atomic-Scale Structure of Amorphous Silica–Alumina and Its Brønsted Acid Sites.” Physical Chemistry Chemical Physics 21, no. 35 (2019): 19529–37.

https://doi.org/10.1039/C9CP04099D

In spite of the widespread applications of amorphous silica–aluminas (ASAs) in many important industrial chemical processes, their high-resolution structures have remained largely elusive. Specifically, the lack of long-range ordering in ASA precludes the use of diffraction methods while NMR spectroscopy has been limited by low sensitivity. Here, we use conventional as well as DNP-enhanced 29Si–29Si, 27Al–27Al, and 29Si–27Al solid-state NMR experiments to shed light on the ordering of atoms in ASAs prepared by flame-spray-pyrolysis. These experiments, in conjunction with a novel Monte Carlo-based approach to simulating RESPDOR dephasing curves, revealed that ASA materials obey Loewenstein’s rule of aluminum avoidance. 3D 17O{1H} and 2D
17O{1H, 27Al} experiments were developed to measure site-specific O–H and HO–Al distances, and show that the Brønsted acid sites originate predominantly from the pseudo-bridging silanol groups.

Microcoils for Broadband Multinuclei Detection

Anders, Jens, and Aldrik H. Velders. “Microcoils for Broadband Multinuclei Detection.” In Micro and Nano Scale NMR, by Jens Anders and Jan G. Korvink, 265–96. Advanced Micro and Nanosystems. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2018.

https://doi.org/10.1002/9783527697281.ch10.

NMR techniques are among the most influential analytical tools developed in the past century and widely used in various disciplines from oil well drilling to medicine. To date, two major hurdles inhibit an even more widespread use of NMR spectroscopy in science and society: first, NMR’s relatively low sensitivity severely constrains applications of mass- and volume-limited samples including lab-on-chip integration, in-cell analysis, and bioanalyte detection. Typical NMR samples contain micromole quantities of material in a relatively large sample volume of about 0.5ml; this large sample volume in turn imposes stringent requirements on the magnetic field – both for the generation but also on the susceptibility of the materials utilized in the probe head – which has to be homogenous in the whole sample volume with ppb resolution. Second, NMR equipment is very complex and costly. A major contribution to the high price of NMR equipment is constituted by the (cryogenic) superconducting magnets used to generate the static magnetic field.This problem will hopefully be tackled by the introduction of new magnet-manufacturing techniques and materials, for example, high-temperature superconductors, and the development of miniaturized spectrometers. Another complex and costly aspect concerns the heart of spectrometers consisting of intricate multifrequency probes, with coils integrated in sophisticated tuning–matching circuits connected to complex RF transceiver circuits. In viewof these limitations of currentNMRsystems, to make NMR more versatile and affordable, a key challenge is improving sensitivity and, at the same time, reducing cost and complexity of NMR probes and electronics.

Quantifying the effects of quadrupolar sinks via 15N relaxation dynamics in metronidazoles hyperpolarized via SABRE-SHEATH

Birchall, Jonathan R., Mohammad S. H. Kabir, Oleg G. Salnikov, Nikita V. Chukanov, Alexandra Svyatova, Kirill V. Kovtunov, Igor V. Koptyug, et al. “Quantifying the Effects of Quadrupolar Sinks via 15N Relaxation Dynamics in Metronidazoles Hyperpolarized via SABRE-SHEATH.” Chemical Communications 56, no. 64 (2020): 9098–9101.

https://doi.org/10.1039/D0CC03994B

15N spin–lattice relaxation dynamics in metronidazole-15N3 and metronidazole-15N2 isotopologues are studied for rational design of 15N-enriched biomolecules for signal amplification by reversible exchange in microtesla fields. 15N relaxation dynamics mapping reveals the deleterious effects of interactions with the polarization transfer catalyst and a quadrupolar 14N nucleus within the spin-relayed 15N–15N network.

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